Trajectory optimization with GA and control for quadruped robots

This paper proposes an optimal galloping trajectory, which costs low energy and guarantees the stability of the quadruped robot. In the realization of fast galloping, the trajectory design is important. For a galloping trajectory, we propose an elliptic leg trajectory, which provides simplified locomotion to complex galloping motions of animals. However, the elliptic trajectory, as an imitation of animal galloping motion, does not guarantee stability and minimal energy consumption. We propose optimization based on energy and stability using a genetic algorithm, which provides a robust and globally optimized solution to this multi-body, highly nonlinear dynamic system. To evaluate and verify the effectiveness of the proposed trajectory, a series of computer simulations were carried out. This paper was recommended for publication in revised form by Associate Editor Doo Yong Lee Jong Hyeon Park received the B.S. degree in mechanical engineering from Seoul National University, Seoul, Korea, in 1981 and the S.M. and Ph.D. degrees from the Massachusetts Institute of Technology (MIT), Cambridge, in 1983 and 1991, respectively. Since 1992, he has been with the School of Mechanical Engineering at Hanyang University, Seoul, Korea, where he is currently a professor. He was a KOSEF (Korea Science and Engineering Foundation)-JSPS (Japan Society for the Promotion of Science) Visiting Researcher with Waseda University, Tokyo, Japan, in 1999, and a KOSEF-CNR (Consiglio Nazionale delle Ricerche) Visiting Researcher with Scuola Superiore Sant’Anna, Pisa, Italy, in 2000, a Visiting Scholar with MIT, Cambridge, USA, in 2002–2003. He was also associated with Brooks Automation Inc., Chelmsford, MA, in 1991–1992 and 2001–2002. His research interests include biped robots, robot dynamics and control, haptics, and bio-robots. He is a member of the IEEE (Institute of Electrical and Electronics Engineers), KSME (Korea Society of Mechanical Engineers), ICROS (Institute of Control, Robotics and Systems), KROS (Korea Robotics Society), KSAE (Korean Society of Automotive Engineers), KSPE (Korean Society of Precision Engineering) and KSEE (Korean Society for Engineering Education).     

Efficiency of grid representation and its algorithms for areal 3D scan data

This paper describes the efficiency of a grid representation for an areal 3D scan data and the algorithms for managing measurement data captured by areal 3D scanners. Due to the measurement principles of areal 3D scanners, a measurement point is generated for each pixel of the imaging sensor inside the 3D scanner. Therefore, when the measurement points are perspectively projected on the image plane of the imaging sensor, each point has one-to-one correspondence to the imaging elements of the sensor that has a regular grid structure. By using this property, measurement points are represented by their depth values in a grid representation model. Compared to the conventional representation model, such as triangular mesh and cloud of points, the grid representation uses less memory and allows efficient algorithms for processing the measurement data captured by areal 3D scanners. This paper was recommended for publication in revised form by Associate Editor Soon Hung Han Minho Chang is a Professor at the department of mechanical engineering at Korea University in Seoul Korea. He received a PhD degree in Mechanical Engineering from MIT in 1996. He worked for Korea Institute of Science and Technology. His research interests include mechanical design, three-dimensional measurement, and CAD. Yun Chan Chung is a Professor in the department of die and mold engineering at Seoul National University of Technology, Korea. He worked for Cubictek and DaimlerChrysler, developing CAD/CAM systems mainly in die and mold making. He received PhD in Industrial Engineering from KAIST in 1996. His research interests include digital manufacturing, tool-path generation and verification, and software engineering.     

Efficiency evaluation of micro factory for micro pump manufacture

The micro factory, a miniature manufacturing system, is a means of achieving higher throughput with minimal space, and minimal consumption of energy and resources by downsizing of production processes. Even though, a micro factory is able to perform whole manufacturing processes like the macro factory, the possibility of improving its manufacturing efficiency has not been considered enough. In this paper, an efficiency index is proposed to calculate the efficiency of the micro factory to manufacture a micro pump. The efficiency index has been proposed based on efficiency definition with input and output parameters of the system. Input parameters include cost of system, processing time and energy. Output parameters represent number of product manufactured from the microfactory. Cost of the system has been categorized by micro assembly machine cost, cost of resources, manipulators’ cost, manufacturing space value, and human operators. Processing time has been categorized by assembly time and material handling time. This paper was recommended for publication in revised form by Associate Editor Dae-Eun Kim Murali Subramaniyam received his B.E. and M.Tech. from India in 2003 and 2005, respectively. Currently, he is pursuing his Ph.D. in Me-chanical Design Engineering under Brain Korea 21 program fellowship at CNU (Chungnam National University), Korea. Also he is working as a research associate in LID (Laboratory of Intelligent Design and manufacturing) at CNU, under Professor Sangho Park. His research interests include CAD/CAM (Computer Aided Design/ Computer Aided Manufac-turing), Computer Integrated Manufacturing, Rapid Prototyping and DHM (Digital Human Modeling). Sangho Park is currently a Professor in Mechanical Design Engineering at CNU. He received his B.S., M.S. and Ph.D. from Seoul National University, Korea in 1988, 1990 and 1995 respectively. He was a Senior Research Scientist at ETRI (Electronics and Telecommunications Research Institute), Korea. His areas of expertise and research interest includes CAD/CAM, Virtual Reality, DHM and Micro Assembly. LID (renamed from CAD/CAM) is doing research under his advice. Sung-il Choi received a B.S. form Konyang University in 1995, Korea. He then received an M.S. from CNU in 1997. Currently, he is pursuing his Ph.D. in Mechanical Design Engineering at CNU. He was a researcher at ETRI. His research intersts include the areas of development of CAD interface, virtual simulation, 3D Web solutions, geometric modelling, micro-assembly, and application of distributed environment. Jun-Yeob Song is a Team Leader in the IT Machinery Research Team, Korea Institute of Machinery and Materials, Korea. Also, He is a Chief of National Research Laboratory on Knowledge Evolution based Manufacturing Devices. He received a Ph. D. from the School of Industrial Engineering at Busan National University in 2001. He has extensive experience in design & control of automation and autonomous manufacturing systems, and reliability engineering. In recent years, Dr. Song’s research interests are in the area of micro assembly, bonding, and multi chip packaging (MCP). Jong-Kweon Park received a B.S. degree in Mechanical Engineering from Inha University in 1977. He then received M.S. and Ph.D. degrees in mechanical engineering from Changwon National University in 1993 and 1997. Dr. Park is currently a principal research at Korea Institute of Machinery and Materials in Daejeon, Korea. His current research areas are cutting dynamics and control, structural dynamics and optimization, ultra precision machining systems, micro/nano manufacturing systems, and design and evaluation of machine tool systems. He is currently a project leader for the project, “Development of Microfactory System Technologies for Next Generation.”     

Experimental and numerical studies on the thermal analysis of the plate in indirectly fired continuous heat treatment furnace

Experimental and numerical studies were performed by considering convective and radiative heat transfer to predict the transient thermal behavior of a plate in an indirectly fired continuous heat treatment furnace. The temperature profiles in the plate were determined by solving the transient one-dimensional heat conduction equation in conjunction with appropriate boundary conditions by using a time marching scheme. The results obtained from the transient analysis were substantiated by comparing with experimental results. Additionally, parametric investigations were performed to examine how the thermal behavior of the plate is affected by plate and refractory emissivities, charging temperature and residence time of the plate, gas temperature of the work and drive sides of the heat treatment furnace, and plate thickness. This paper was recommended for publication in revised form by Associate Editor Ohchae Kwon Young-Deuk Kim is a graduate student at Hanyang University in Seoul, Korea. He earned his B.S. in Mechanical Engineering from Korea Maritime University in 2002 and his M.S. in mechanical engineering from Hanyang university in 2004. His current research areas are modeling of automotive aftertreatment catalysts, optimal design of thermal systems, and phase change modeling with free surface flow. Deok-Hong Kang is a senior researcher at the RIST (Research Institute of Industrial Science and Technology) in Pohang, Korea. He earned his B.S. and M.S. in mechanical engineering from Hanyang University in 1989 and 1993, respectively, and his Ph.D. in mechanical engineering from POSTECH in 2004. His current research areas are mathematical modeling for combustion control, furnace optimization control system, and energy saving engineering in all kinds of furnaces. Woo-Seung Kim is a professor in mechanical engineering at Hanyang University in Ansan, Korea. He earned his B.S. in Mechanical Engineering in 1981 from Hanyang University and his M.S. and Ph.D. in mechanical engineering from North Carolina State University in 1986 and 1989, respectively. His current research areas are modeling of automotive aftertreatment systems, inverse heat transfer problems, optimal design of thermal systems, and phase change heat transfer problems with free surface flow.     

Investigation of emission characteristics affected by new cooling system in a diesel engine

In a typical cooling system of automotive engine, a mechanical water pump is used to control the flow rate of coolant. However, this traditional cooling system is not suitable for a high efficiency performance in terms of fuel economy and exhaust emission. Therefore, it is necessary to develop a new technology for engine cooling systems. These days, the electronic water pump is spotlighted as the new cooling system of an engine. The new cooling system can provide more flexible control of the coolant flow rate and the engine temperature, which used to be strongly relied on the engine driving conditions such as load and speed. In this study, an engine experiment was carried out on a New European Drive Cycle (NEDC) with a 2.7L diesel engine. The electric water pump operated by BLDC motor and the electronic valve were installed in the cooling system to control the coolant flow rate and temperature. This paper explains that the exhaust emissions were reduced with an increase in the engine temperature and a decrease in the coolant flow. From this experiment, we found that increasing coolant temperature had a significant effect on reducing the emissions (e.g. THC and CO). Decreasing coolant flow also affected the reduction of emissions. In contrast, NOx emission was observed to increase in these conditions. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Kyung-Wook Choi received his B.S. degree in Mechanical Engineering from Hanyang University, Korea, in 2006. He is now working on a doctoral degree in Hanyang University. Kyung-Wook’s research interests include Hybrid Electric Vehicle, Internal Engine Combustion, and Engine Cooling System. Ki-bum Kim was awarded a bachelor’s degree in naval architecture and ocean engineering from Chung-Nam National University in the Republic of Korea. In August 2001, he began graduate study at the University of Florida. Kibum graduated with a Master of Science degree in mechanical engineering from the University of Florida in August 2003. He went on to earn his Ph.D. in mechanical engineering, also at the University of Florida, in August 2006. He is working as a research professor at Hanyang University. Ki-Hyung Lee is a Professor at the department of mechanical engineering in Hanyang University. He received his B.S and M.S degree in Hanyang University in 1983 and 1986. Then he graduated with a Ph.D. degree in mechanical Engineering at Kobe University, Japan in 1989. He worked as a research engineer at Nissan motor’s central technical center for 4 years.     

Evaporation of inkjet printed pico-liter droplet on heated substrates with different thermal conductivity

In this work, the evaporation phenomena of 20–45 picoliter water droplet (i.e. 50–65 μm diameter) on heated substrates with different thermal conductivity are studied experimentally. The effect of thermal conductivity of substrates and inter-distance between jetted droplets on the evaporation is investigated. In addition, the model to predict evaporation rate of the picoliter droplet on different substrates at a heated condition is developed using approximations for picoliter droplet. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Taewoong Lim received his B.S and M.S. degree in mechanical engineering from Korea University, Seoul, Korea in 2007 and 2009, respectively. His thesis topic was the evaporation of inkjet printed pico-liter droplet and He has been working at Hyundai Motor Company. Jaeik Jeong received his B.S. degree in mechanical engineering from Korea University in 2008. He is currently a M.S. candidate in mechanical engineering at Korea University. Jaewon Chung received his B.S. and M.S. degrees in mechanical engineering from Yonsei University, Seoul, Korea in 1995 and 1997, respectively and Ph.D. degree from University of California, Berkley in 2002. He was postdoctoral associate in Engineering System Research Center at University of California, Berkley in 2002–2004 and had worked in the Center of Micro and Nano Technology at Lawrence Livermore National Laboratory as a visiting collaborator. He is a currently an associate professor at the Department of Mechanical Engineering at Korea University in Seoul, Korea. His research interests include direct writing methods including drop on demand inkjet printing, electrohydrodynamic printing and laser material processing for printing electronics. Jin Taek Chung received his B.S. and M.S. degrees in mechanical engineering from Korea University, Seoul, Korea in 1983 and 1985, respectively and Ph. D. degree from University of Minnesota, U.S.A. in 1992. He is a currently a professor at the Department of Mechanical Engineering at Korea University in Seoul, Korea. His research interests are heat transfer and 3-D flow in gas turbines and thermal management of electronic devices.     

A numerical study on oil retention and migration characteristics in the heat pump system

In HVAC system, the oil circulation is inevitable because the compressor requires the oil for lubrication and sealing. A small portion of the oil circulates with the refrigerant flow through the system components while most of the oil stays or goes back to the compressor. Because oil retention in refrigeration systems can affect system performance and compressor reliability, proper oil management is necessary in order to improve the compressor reliability and increase the overall efficiency of the system. This paper describes a numerical analysis of oil distribution in each component of the commercial air conditioning system including the suction line, discharge line and heat exchanger. In this study, system modeling was conducted for a compressor, discharge line, condenser, expansion valve, evaporator and suction line. Oil separation characteristics of the compressor were taken from the information provided by manufacturer. The working fluid in the system was a mixture of a R-410A refrigerant and PVE oil. When the oil mass fraction (OMF) was assumed, oil mass distribution in each component was obtained under various conditions. The total oil hold-up was also investigated, and the suction line contained the largest oil hold-up per unit length of all components. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Min Soo Kim received his B.S., M.S., and Ph.D. degree at Seoul National University, Korea in 1985, 1987, and 1991, respectively. After Ph.D. degree, Prof. Kim worked at National Institute of Standards and Technology (NIST) in U.S.A. for about three years. He is currently a professor at the School of Mechanical and Aerospace Engineering of Seoul National University, Korea. Jong Won Choi received B.S. degree in Mechanical Engineering from Korea University in Seoul, Korea, in 2004, and then received M.S. degrees from Seoul National University in 2006. He is currently a student in Ph.D. course at the School of Mechanical and Aerospace Engineering of Seoul National University in Seoul, Korea. His research interests include refrigeration system, micro-fluidic devices, and PEM fuel cell as an alternative energy for next generation. Mo Se Kim received B.S. degree in Mechanical and Aerospace Engineering from Seoul National University in Seoul, Korea, in 2007. He is currently a student in M.S. course at the School of Mechanical and Aerospace Engineering of Seoul National University in Seoul, Korea. He had studied on the oil migration in the heat pump system, and now he studies on the refrigeration system using an ejector. Baik-Young Chung received his B.S., M.S., and Ph.D. degrees in Mechanical Engineering from Inha University, Korea in 1984, 1986, and 2001, respectively. He is currently a research fellow of HAC Research Center at LG Electronics. He is responsible for the commercial air conditioner group. Sai-Kee Oh received B.S. degree in Mechanical Engineering from Seoul National University, Korea in 1989, and then received M.S. and Ph.D. degrees from KAIST, Korea in 1991 and 1997, respectively. He is currently a principal research engineer of HAC Research Center at LG Electronics. He is responsible for the residential air conditioner group. Jeong-Seob Shin received B.S. degree in Machine Design and Production Engineering from Hanyang University, Korea in 1988, M.S. degree in Mechanical Engineering from KAIST, Korea in 1991, and Ph.D. degree in Mechanical Engineering from POSTECH, Korea in 2004. He has joined HAC Research Center at LG Electronics since 2006 as a principal research engineer.     

Approximate velocity scale for primary and secondary dual-inlet side-dump flows

Effects of the bulk inlet velocity on the characteristics of dual-inlet side-dump flows are numerically investigated. Non-reacting subsonic turbulent flow is solved by a preconditioned Reynolds-averaged Navier-Stokes equation system with low-Reynolds number k − ɛ turbulence model. The numerical method is properly validated with measured velocity distributions in the head dome and the combustor. With substantial increase in the bulk inlet velocity, general profiles of essential primary and secondary flows normalized by the bulk inlet velocity are quantitatively invariant to the changes in the bulk inlet velocity. This paper was recommended for publication in revised form by Associate Editor Do Hyung Lee Seung-chai Jung received his B.S. degree in Mechanical Engineering from Yonsei University, Korea, in 2001. He then received his M.S. degree in Mechanical Engineering from Yonsei University, Korea, in 2005. Mr. Jung is currently a Ph. D. candidate at Yonsei University, where he is majoring in Mechanical Engineering. Mr. Jung’s research interests include propulsion system and particle-surface collision dynamics. Byung-Hoon Park received his B.S. degree in Mechanical Design and Production Engineering from Yonsei University in 2003. He is currently a Ph.D. candidate in Yonsei University in Seoul, Korea. His research interests include performance design of propulsion systems and nu-merical analysis of instability in multiphase turbulent reacting flow-fields. Hyun Ko received his B.S. degree in Aerospace Engineering from Chonbuk National University, Korea, in 1996. He then received his M.S. degree in Mechanical Design from Chonbuk National University, Korea, in 1998. In 2005, he obtained his Ph.D. degree from Yonsei University, where he majored in mechanical engineering. Dr. Ko is currently a Principal Research Engineer of the MicroFriend Co., Ltd. in Seoul, Korea. His research interests include propulsion related systems and computational fluid dynamics. Woong-sup Yoon received his B.S. degree in Mechanical Engineering from Yonsei University, Korea, in 1985. He then received his M.S. degree from University of Missouri-Rolla in 1989. In 1992, he obtained his Ph.D. degree from the University of Alabama in Huntsville, where he majored in mechanical and aerospace engineering. Dr. Yoon is currently a professor at the School of Mechanical Engineering at Yonsei University in Seoul, Korea. His research interests include propulsion system and particle-related environmental/ thermal engineering.     

Mapping of the morphological and the material characteristics on the glenoid and estimation of predominant loading condition on the glenoid through the mapping

The aim of this study was to predict and map the regional distribution of the trabecular architecture and the material properties of the glenoid and to estimate the predominant loading condition on the glenoid through the mapping. The morphological and material characteristics of the glenoid were investigated by analyzing digitized trabecular bone images obtained from twelve cadaver scapula specimens. The morphological and material characteristics computed from the cadaver specimens show that the predominant loading on the glenoid generally occurs during shoulder movement, which produces forces directed toward the posterior aspect of the bare region. This study is innovative in its detailed mapping of the morphological and material characteristics of the glenoid and its pioneering approach used to estimate the loading pattern acting on the glenoid through the mapping. This paper was recommended for publication in revised form by Associate Editor Young Eun Kim Dohyung Lim received B.S. and M.S. degrees in Biomedical Engineering from Inje University, Kimhae, Korea, in 1998 and 2000, respectively. He then went on to receive his Ph.D. degree from School of Biomedical Engineering, Science, & Health Systems, Drexel University, Philadelphia, PA, USA, in 2004. Dr. Lim completed a postdoctoral fellowship in Department of Physical Therapy and Human Movement Science, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA and a Research Professor of Biomedical Engineering, Yonsei University, Wonju, Gangwon, Korea. Dr. Lim is currently a Senior Researcher at the Korea Institute of Industrial Technology in Cheonan, Chungnam, Korea. Han-Sung Kim received B.S. and M.S. degrees in Machine Design and Production Engineering from Hanyang University, Seoul, Korea, in 1989 and 1991, respectively. Dr. Kim received Ph.D. degree in Mechanical Engineering from University of Manchester Institute of Science and Technology, Manchester, UK, in 1999. Dr. Kim is currently an Associated Professor at the Biomedical Engineering at Yonsei University in Wonju, Korea. Jung-Sung Kim received B.S. and M.S. degrees in Biomedical Engineering from Inje University, Kimhae, Korea, in 1996 and 1998, respectively. He is currently in the doctor’s course in Department of Medical Engineering and BK 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea. Rami Seliktar has a BS and MS degree in Mechanical Engineering, from The Technion, IIT, and Ph.D. (BME) from Strathclyde University, Scotland. He has held academic appointments in several institutions worldwide: Strathclyde University (2yrs.); associate professor at the Technion (9yrs.); Texas A&M (on sabbatical leave from the Technion), and twenty seven years as professor of BME and ME at Drexel University in Philadelphia. Concurrently he founded and directed a Biomechanics laboratory at the Loewenstein Rehab. in Israel and consulted to governments, public agencies and industries. Prof. Seliktar has done research on limb prosthetics, human performance, orthopedic and occupational biomechanics, assistive technology for automomobil dynamics. His research has been funded by: The NSF, NIH, the RWJ Foundation, the Easter Seal Foundation, NIDRR, AIduPont, the United Cerebral Palsy and some hospitals. He has published numerous articles in scientific journals, book chapters and conference proceedings. At the present, Rami Seliktar is Professor and Vice Director of the School of Biomedical Engineering, Science and Health Systems of Drexel University. Sung-Jae Lee received B.S. and M.Eng. degrees in Mechanical Engineering from Cornell University, Ithaca, NY, USA, in 1984 and 1985, respectively. He re-ceived Ph.D. degree in Biomedical Engineering from University of Iowa, Iowa City, IA, USA, in 1993 Dr. Lee is currently a Professor at Department of Biomedical Engineering, Inje University, Gimhae, Gyongnam, Korea. He is currently serving as a board member for the Division for Health Care Technology Assessment of International Federation of Medical and Biological Engineering (IFMBE), a executive member of Korean Orthopedic Research Society, director of international relations for the Korean Society for Biomaterials and also for the Korean Society of Biomechanics.     

Tolerance effects on natural frequencies of multibody systems undergoing constant rotational motion

A general multi-body formulation to analyze the tolerance effects on the statistical property variations of natural frequencies of multi-body systems undergoing constant rotational motion is proposed in this paper. To obtain the tolerance effects, Monte-Carlo simulation method is conventionally employed. However, the Monte-Carlo simulation has serious drawbacks; spending too much computation time for the simulation and achieving very slow convergence around some dynamically unstable regions. To resolve such problems, a method employing analytical sensitivity information is suggested in this paper. To obtain the sensitivities of natural frequencies the eigenvalue problem should be differentiated with respect to a design variable. The sensitivities of mass and stiffness matrices should be calculated at the dynamic equilibrium. By employing the sensitivities of natural frequencies along with the tolerance of the design variable, the statistical property variations of the natural frequencies can be calculated. This paper was recommended for publication in revised form by Associate Editor Seockhyun Kim Seung Man Eom graduated from the Department of Mechanical Engineering at Incheon University in 2005 and received his master degree from the Department of Mechanical Engineering at Hanyang University in 2007. He is currently working as a Researcher of Aircraft Development Team in KIAT(Korea Institute of Aerospace Technology, Koreanair), DaejeonDeajeon, Korea. Bum Suk Kim graduated from the School of Mechanical Engineering at Hanyang University in 2006 and received his master degree from the same department in 2008. He is currently working as a Ph.D. student in the School of Mechanical Engineering in Hanyang University, Seoul, Korea. Hong Hee Yoo graduated from the Department of Mechanical Design and Production Engineering at Seoul National University in 1980 and received his master degree from the same department in 1982. He received his Ph.D. degree in 1989 from the Department of Mechanical Engineering and Applied Mechanics in the University of Michigan at Ann Arbor, U.S.A. He is currently working as a professor in the School of Mechanical Engineering in Hanyang University, Seoul, Korea.     

Numerical solutions for unsteady flow past a semi-infinite inclined plate with temperature oscillations

A study of the velocity and thermal boundary layers on a semi-infinite inclined plate with temperature oscillations is presented in this work. The non-linear, coupled parabolic integro-partial differential equations governing flow and heat transfer have been solved numerically using an implicit finite difference scheme of Crank-Nicolson type. The numerical values for the flow field, temperature, shearing stress, and heat transfer coefficients are presented in a graphical form. It is observed that the velocity and temperature profiles decrease as the frequency parameter increases. This paper was recommended for publication in revised form by Associate Editor Yang Na G. Palani received his B.Sc. and M.Sc. degrees from Madras University, India, in 1991 and 1993, respectively, and his Ph.D. degree from Anna University, India in 2001. Dr. G. Palani is currently a Post Doctoral Research Fellow at the School of Mechanical Engineering of Inha University in Incheon, Korea. Kwang-Yong Kim received his B.S. degree from Seoul National University in 1978, and his M.S. and Ph.D. degrees from the Korea Advanced Institute of Science and Technology (KAIST), Korea, in 1981 and 1987, respectively. He is currently a professor and the chairman of the School of Mechanical Engineering of Inha University, Incheon, Korea. Professor Kim is also the current editor-inchief of the Transactions of Korean Society of Mechanical Engineers (KSME), the editor-in-chief of the International Journal of Fluid Machinery and Systems (IJFMS), and the chief vice president of the Korean Fluid Machinery Association (KFMA). He is likewise a fellow of the American Society of Mechanical Engineers (ASME).     

Development of an authoring framework for the simplified customization of PDM systems

Given that the amount of product data in firms is explosively increasing, a PDM system for effective data management is considered indispensable for product development. However, considerable time and specialized human resources are needed to customize a generic PDM system for satisfying the specific requirements of individual firms. To overcome this problem, we propose the use of UML object models in a PDM authoring framework. A PDM authoring framework, which provides authoring functions for the effective customization of PDM systems, will reduce the need for the intervention of PDM specialists in the design of the object models of the PDM system. We describe how a PDM authoring framework may be designed by using UML object models, and show how model-oriented application development (MOAD), in conjunction with the PDM authoring framework, can be used to build object models into a PDM system. Furthermore, we confirm the value of the framework by evaluating its performance under several conditions. This paper was recommended for publication in revised form by Associate Editor Dae-Eun Kim Inho Song is a postdoctoral associate in the Department of Mechanical Engineering, Carnegie Mellon University, USA. He received the Ph.D. degree in Mechanical Engineering from Hanyang University, Seoul, Korea in 2007. From 2002 to 2007, he served as a CAx team leader of the INOPS Company (CIES R&D Center), Seoul, Korea. He has developed the sketch-based CAD system for an automotive company. His research interests include collaborative design, sketch-based CAD, geometry translation, geometry compression, product data exchange, PDM/PLM, digital manufacturing, and virtual reality. Jeongsam Yang is an assistant professor in the Department of Industrial & Information Systems Engineering and is leading the CAD laboratory() at Ajou University. He worked at Clausthal University of Technology (Germany) as a visiting researcher and the University of Wisconsin-Madison (USA) as a postdoctoral associate. He obtained his Ph.D. in mechanical engineering in 2004 at KAIST. His current research interests are product data quality (PDQ), VR application in product design, product data management (PDM), knowledge-based design system, and STEP. Peom Park is a professor in the Department of Industrial & Information Systems Engineering and is leading the Human Technology Research Center and Human Factors/HCI laboratory () at Ajou University. He worked on HCI and Telecommunication system at ETRI as a senior researcher. He obtained his Ph.D. in Industrial and Manufacturing Systems Engineering at Iowa State University on 1992. His current research interests are uT applications, u-Healthcare/Telemedicine, Telematics and Ergonomic/Safety Design.     

Experimental study on heat transfer characteristics of internal heat exchangers for CO2 system under cooling condition

This paper presents the heat transfer characteristics of the internal heat exchanger (IHX) for CO₂ heat pump system. The influence on the IHX length, the mass flow rate, the shape of IHX, the operating condition, and the oil concentration was investigated under a cooling condition. Four kinds of IHX with a coaxial type and a micro-channel type, a mass flow meter, a pump, and a measurement system. With increasing of the IHX length, the capacity, the effectiveness, and the pressure drop increased. For the mass flow rate, the capacity of micro-channel IHX are higher about 2 times than those of coaxial IHX. The pressure drop was larger at cold-side than at hot-side. In the transcritical CO₂ cycle, system performance is very sensitive to the IHX design. Design parameters are closely related with the capacity and the pressure drop of CO₂ heat pump system. Along the operating condition, the performance of CO₂ IHXs is different remarkably. For oil concentration 1, 3, 5%, the capacity decreases and the pressure drop increased, as compared with oil concentration 0%. This paper was recommended for publication in revised form by Associate Editor Yong Tae Kang Prof. Young-Chul Kwon received his B.S. degree in Precision Mechanical Engineering from Pusan National University, Korea, in 1989. He then received his M.S. and Ph.D. degrees from POSTECH, in 1991 and 1996, respectively. Dr. Kwon is currently a Professor at the Division of Mechanical Engineering at Sunmoon University in Chungnam, Korea. He serves as a chief of the Institute of Automation and Energy Technology. Dr. Kwon’s research interests include heat exchanger, CO₂ cycle, heat pump, and energy recovery ventilator for HVAC&R. Mr. Dae-Hoon Kim is currently Doctoral student at the Mechanical Engineering from Hanyang University in Seoul, Korea. His research topics include experimental and numerical of CO₂ heatpump system. He has conducted a study on the Analysis of Refrigerating & Air-Conditioning Equipment Industry and Its Forecasting Supervising and Testing for Performance of Refrigerator, Freezer and Air-Conditioner. Prof. Jae-Heon Lee received his B.S. degree in Mechanical Engineering from Seoul National University, Korea, in 1971. He then received his M.S. and Ph. D. degree from Seoul National University in 1977 and 1980, respectively. Dr. Lee is currently a Professor at the school of Mechanical Engineering at Hanyang University in Seoul, Korea. Dr. Lee is currently a president at the Korea Institute research interests include simulation of thermal fluid and Plant engineering and construction. Dr. Jun-Young Choi received his B.S. degree in Mechanical Engineering from Yonsei University, Republic of Korea, in 1989. He then received his M.S. and Ph. D. degrees from Yonsei University in 1991 and 1999, respectively. Dr. Choi is currently a chief researcher with the 18 years experience on the energy performance testing of HVAC/R product. He is now assigned to the Energy Technology Center at Basic Industry Division at Korea Testing Laboratory. He has been involved in the development of Design and Manufacturing Technology for Air-Conditioner E.E.R. and Performance Testing Equipment for Cooling and Heating System with Non-CFCs, and natural refrigerants. He has conducted a study on the Analysis of Refrigerating & Air-Conditioning Equipment Industry and Its Forecasting Supervising and Testing for Performance of Refrigerator, Freezer and Air-Conditioner. Dr. Sang Jae Lee received his Ph.D. degree in Mechanical Engineering from Hanyang University, KOREA, in 2008. Dr. Lee is currently a Researcher at the Korea Institute of Industrial Technology in Cheonan, Korea. Dr. Lee’s research interests CO₂ heatpump system, liquid desiccant air conditioning system and Micro heat exchanger.     

Analysis of the combustion instability of a model gas turbine combustor by the transfer matrix method

Combustion instability is a major issue in design of gas turbine combustors for efficient operation with low emissions. A transfer matrix-based approach is developed in this work for the stability analysis of gas turbine combustors. By viewing the combustor cavity as a one-dimensional acoustic system with a side branch, the heat source located inside the cavity can be described as the input to the system. The combustion process is modeled as a closed-loop feedback system, which enables utilization of well-established classic control theories for the stability analysis. Due to the inherent advantage of the transfer matrix method and control system representation, modeling and analysis of the system becomes a straightforward task even for a combustor of the complex geometry. The approach is applied to the stability analysis of a simple combustion system to demonstrate its validity and effectiveness. This paper was recommended for publication in revised form by Associate Editor Ohchae Kwon Dong Jin Cha received his B.S. and M.S. degrees from Hanyang University in Seoul, Korea, in 1981 and 1983, respectively. He then received his Ph.D. in ME from the University of Illinois at Chicago in 1992, and worked at the US DOE NETL for the next three years as a National Research Council (NRC) Associate. Dr. Cha is currently a Professor at the Department of Building Services Engineering at Hanbat National University in Daejeon, Korea. His research interests include combustion instability of gas turbine for power generation and fluid flows in building services engineering. Jay H. Kim received his BSME from Seoul National University in 1977, MSME from KAIST in 1979 and Ph.D. in ME from Purdue University in 1988. He has joined the Mechanical Engineering faculty of the University of Cincinnati in 1990, and is currently a Professor. Before joining the University of Cincinnati, he worked in industry for six years in Korea and US. His research interests have been in broad areas of acoustics, vibrations and applied mechanics with recent focuses on human/bioacoustics and vibration, gas pulsations and elastic stability. Yong-Jin Joo received his BSME and MSME from Sung Kyun Kwan University in Seoul, Korea, in 1990 and 1992, respectively. Mr. Joo is currently a Project Leader for IGCC Operation Technologies at KEPRI (Korea Electric Power Research Institute) which is the central R&D center of KEPCO (Korea Electric Power Corporation). His research interests include the development of operation and maintenance simulator for power plants including IGCC.     

Development of rapid mixing fuel nozzle for premixed combustion

Combustion in high-preheat and low oxygen concentration atmosphere is one of the attractive measures to reduce nitric oxide emission as well as greenhouse gases from combustion devices, and it is expected to be a key technology for the industrial applications in heating devices and furnaces. Before proceeding to the practical applications, we need to elucidate combustion characteristics of non-premixed and premixed flames in high-preheat and low oxygen concentration conditions from scientific point of view. For the purpose, we have developed a special mixing nozzle to create a homogeneous mixture of fuel and air by rapid mixing, and applied this rapidmixing nozzle to a Bunsen-type burner to observe combustion characteristics of the rapid-mixture. As a result, the combustion of rapid-mixture exhibited the same flame structure and combustion characteristics as the perfectly prepared premixed flame, even though the mixing time of the rapid-mixing nozzle was extremely short as a few milliseconds. Therefore, the rapid-mixing nozzle in this paper can be used to create preheated premixed flames as far as the mixing time is shorter than the ignition delay time of the fuel. This paper was recommended for publication in revised form by Associate Editor Ohchae Kwon Masashi Katsuki received his B.E. degree in Mechanical Engineering from Osaka University, Japan, in 1965. He received his Dr. Eng. from O. U. in 1985. Dr. Katsuki is currently a Visiting Professor at the Department of Environmental Engineering at Hoseo University in Chungnam, Korea. He was a Vice President of the Japan Society of Mechanical Engineers. Dr. Katsuki’s research interests include combustion, computational thermo-fluid dynamics, and molecular dynamics. Jin-Do Chung received his B. S., M.S. and Ph.D. degrees in Mechanical Engineering from Chungnam University, Korea in 1983, 1985 and 1990. He then received another Ph.D. in Environmental Engineering from Kanazawa University, Japan in 1996. After that he worked as Post-doc researcher for 1,6 year at KIMM and Senior researcher for 6years at KEPCO Research Center. Dr. Chung is currently a Professor at the Department of Environmental Engineering at Hoseo University in Asan, Korea. Dr. Chung’s research interests include thermal-fluid and environmental engineering. Jang-Woo Kim received his B. S. degree in Mechanical Engineering from Chungnam University, Korea, in 1990. He then received his M. S. and Ph. D. degrees from Kyushu University, Japan in 1994 and 1998, respectively. Dr. Kim is currently a Professor at the School of Display Engineering at Hoseo University in Asan, Korea. Dr. Kim’s research interests include CFD, aerodynamics, and display equipment technology. Seung-Min Hwang received the Ph.D. degree in Mechanical Engineering at Osaka University in 2005. After that he worked as visiting researcher for 3 years at CRIEPI (central research institute of electric power industry) and Osaka University in Japan. He is currently a Professor at the Graduate School of Venture at Hoseo University in Korea. His major research is thermal-fluid, energy issue and environment. Seung-Mo Kim received his Ph. D. degrees in Mechanical engineering from Osaka University, Japan, in 2004. Dr. Kim is currently a research Professor at Pusan Clean Coal Center at Pusan National University in Pusan, South Korea. Dr. Kim’s research interests include coal combustion, oxy-fuel combustion, coal gasification, coal de-watering, power generation plant system and energy issues. Chul-Ju Ahn received his B.S. degree in Mechanical Engineering from Hanyang University, Korea, in 1998. He then received his M.S. and Ph.D. degrees from Osaka University, Japan, in 2001 and 2006, respectively. Dr. Ahn is currently a Senior Research Engineer at Samsung Techwin CO. LTD. in Changwon, Korea. Dr. Ahn’s research interests include gas turbine engine, biomass gasification, and power system.     

Optimization of rapid thermal processing for uniform temperature distribution on wafer surface

An optimization of rapid thermal processing (RTP) was conducted to obtain uniform temperature distribution on a wafer surface by using linear programming and radiative heat transfer modeling. The results show that two heating lamp zones are needed to maintain uniform wafer temperature and the optimal lamp positions are unique for a given geometry and not affected by wafer temperatures. The radii of heating lamps, which were obtained by optimization, are 45 mm and 108 mm. The emissivity and temperature of the chamber wall do not significantly affect the optimal condition. With obtained optimum geometry of the RTP chamber and lamp positions, the wafer surface temperatures were calculated. The uniformity allowance of the wafer surface is less than ±1°C when the mean temperature of the wafer surface is 1000°C. This paper was recommended for publication in revised form by Associate Editor Dongsik Kim Hyuck-Keun Oh received the B.S. and M.S degrees in Mechanical & Aerospace Engineering from Seoul National University in 2000 and 2002, respectively. He had experienced mechanical and electrical engineering in the Samsung SDI Corporation on various display devices between 2002 and 2007. He is now pursuing the Ph.D degree in Mechanical & Aerospace engineering at Seoul National University, Korea. His research interests are heat transfer and thermal management with a focus on power generation and energy efficiency. Sae Byul Kang received the B.S degree in Mechanical engineering from Korea University in 1996. He then went on to receive his M.S and Ph.D. degrees from Seoul National University in 1998 and 2003, respectively. Dr. Kang is currently a senior researcher at the Korea Institute of Energy Research in Daejeon, Korea. Dr. Kang’s research interests are development of industrial boiler and burner for bio-mass. Young Ki Choi received the B.S and M.S degrees in Mechanical engineering from Seoul National University in 1978 and 1980, respectively and the Ph.D. de-gree in mechanical engineering from the University of California at Berkeley in 1986. He is currently a professor at the School of Mechanical Engineering, Chung Ang University, Korea. His research interests are in the area of micro/nanoscale energy conversion and transport, computational fluid dynamics, and molecular dynamics simulations. Joon Sik Lee received the B.S and M.S degrees in Mechanical engineering from Seoul National University in 1976 and 1980, respectively and the Ph.D. degree in mechanical engineering from the University of California at Berkeley in 1985. He is currently a professor at the School of Mechanical & Aerospace Engineering, Seoul National University, Korea. He is also the director of Micro Thermal System Research Center. His research interests are in the area of micro/nanoscale energy conversion and transport, thermal management for power generation and energy efficiency, and various convective heat transport phenomena such as pool boiling and nanofluid.     

Hydraulic transport of sand-water mixtures in pipelines Part I. Experiment

The hydraulic transport characteristics of sand-water mixtures in circular and square pipelines are experimentally investigated by changing the Reynolds number and volumetric delivered concentration. The hydraulic gradients are increased along with the Reynolds number. When the mean velocity is larger than the critical velocity, the hydraulic gradient of sand-water mixture in the square duct is larger than that in the circular pipe. The deposition-limit velocity in the square duct is smaller than that in the circular pipe. Thus, it can be concluded that the square duct transports sands more effectively than the circular pipe in a low operating range of velocity. The empirical correlation between the hydraulic gradient and the Reynolds number is obtained. It is believed that the present data and empirical equation can be used to validate the numerical methods developed for the analysis of the transport characteristics of slurry in the circular and square pipelines. This paper was recommended for publication in revised form by Associate Editor Jun Sang Park Chang-Hee Kim received a B.S. degree in Mechanical Engineering from Hanyang University in 1985. He then went on to receive his M.S. degrees from Hanyang University in 1994. Mr. Kim has joined Hyundai Engineering and Construction Company after his degree and is currently working for Oil & Gas Plant as a Procurement Manager. Man-Soo Lee received his M.S. and Ph.D. degrees from civil eng. dept. of Seoul National University in 1992 and 2004, respectively. He has joined Hyundai Engineering and Construction company since 1991 as a research engineer. Recently assisting a big dredging & reclamation project of Hyundai near Incheon Airport in Korea, he is responsible for the geotechnical researching team of civil engineering division at Hyundai Institute of Construction Technology. Cheol-Heui Han received a B.S. degree in Mechanical Engineering from Hanyang University in 1993. He received his M.S. and Ph.D. degrees from Hanyang University. in 1998 and 2003, respectively. Then, he worked as a visiting post-doctoral researcher at the Dept. of Aerospace and Ocean Engineering at Virginia Tech, USA. Dr. Han is currently a Assistant Professor at the Department of Aeronautical and Mechanical Design Engineering. Dr. Han’s research interests are in the area of biomimetics, aircraft and turbomachine design.     

Modal analysis of a multi-blade system undergoing rotational motion

A modeling method for the modal analysis of a multi-blade system undergoing rotational motion is presented in this paper. Blades are assumed as cantilever beams and the coupling stiffness which originates from the shroud flexibility is considered for the modeling. To obtain general conclusions from the numerical results, the equations of motion are transformed into a dimensionless form. Dimensionless parameters related to the angular speed, the hub radius, and the coupling stiffness are identified and the effects of the parameters on the modal characteristics of the system are investigated. It is shown that the coupling stiffness especially plays an important role to change the modal characteristics of the system. The range of critical angular speed is also obtained through the numerical analysis. This paper was recommended for publication in revised form by Associate Editor Seockhyun Kim Ha Seong Lim graduated from Department of Mechanical Engineering at Hanyang University in 2006 and received his Master’s degree in 2008. He is currently a technical engineer in STX Offshore & Shipbuilding Company, Seoul, Korea. Hong Hee Yoo graduated from the Department of Mechanical Design and Production Engineering at Seoul National University in 1980 and received his Master’s degree from the same department in 1982. He received his Ph.D. degree in 1989 from the Department of Mechanical Engineering and Applied Mechanics at the University of Michigan at Ann Arbor, U.S.A. He is currently a professor in the School of Mechanical Engineering in Hanyang University, Seoul, Korea.     

Electroosmotically enhanced microchannel heat sinks

The present study investigates the microchannel heat sink for pure electroosmotic, pressure-driven, and mixed (electroosmotic and pressure-driven) flows. A three-dimensional numerical analysis is performed for electroosmotic and mixed flows. Electroosmotic flow (EOF) induced in an ionic solution in the presence of surface charge and electric field is investigated with hydrodynamic pressure-driven flow (PDF) to enhance heat removal through the microchannel heat sink. In a pressure-driven microchannel heat sink, the application of an external electric field increases the flow rate that consequently reduces the thermal resistance. The effects of ionic concentration represented by the zeta potential and Debye thickness are studied with the various steps of externally applied electric potential. A higher value of zeta potential leads to higher flow rate and lower thermal resistance, which consequently reduce the temperature of the microprocessor chip and load of the micropump used to supply coolant to the microchannels. This paper was recommended for publication in revised form by Associate Editor Do Hyung Lee Afzal Husain received B.E. and M.Tech. degrees in Mechanical Engineering with specialization in Thermal Sciences from Aligarh Muslim University, India in 2003 and 2005, respectively. Currently he is pursuing Ph.D. degree in Thermodynamics and Fluid Mechanics in Inha University, Republic of Korea. His research interests are numerical analysis and optimization of heat transfer systems using computational fluid dynamics and surrogate models, development of heat transfer augmentation techniques for conventional and micro systems, thermal analysis of microelectromechanical systems (MEMS), and electronic cooling. Kwang-Yong Kim received a B.S. degree from Seoul National University in 1978, and his M.S. and Ph.D. degrees from Korea Advanced Institute of Science and Technology (KAIST), Korea, in 1981 and 1987, respectively. Presently, he is professor and chairman, School of Mechanical Engineering, Inha University, Incheon, Korea. Prof. Kim is presently the editor-in-chief of Transactions of Korean Society of Mechanical Engineers (KSME), the editor-in-chief of International Journal of Fluid Machinery and Systems (IJFMS), and chief vice president of Korean Fluid Machinery Association (KFMA). Prof. Kim is Fellow of American Society of Mechanical Engineers (ASME).     

Parameter study for a dimple location in a space grid under the critical impact load

The spacer grid assembly, an interconnected array of slotted grid straps embossed with dimples and springs, is one of the main structural components of a pressurized light-water reactor (PWR). It takes the role of supporting the nuclear fuel rods which experience a severe expansion and contraction caused by harsh operational conditions such as an earthquake. The external load by an earthquake can be mainly represented as a lateral load, and the resistance to it is evaluated in terms of dynamic crush strengths. It has been reported that a dimple location in a space grid has an effect on this strength. In this paper, based on this fact, the effect of a dimple location in a 3×3 support grid on impact strength has been investigated as a preliminary parameter study for a full sized support grid. The optimal location of the dimple, about 3.5 mm from the tip of the strap, has been found and some design guidelines for a support grid such as reducing the spring length and the dimple gap have been provided. This paper was recommended for publication in revised form by Associate Editor Heoung-Jae Chun Keenam Song received his B.S. degree in the department of mechanical engineering from Seoul National University in 1980, then went on to receive his M.S. degree at KAIST in 1982. Since then he has served as a researcher, senior researcher, principal researcher, and project manager at Korea Atomic Energy Research Institute. Soobum Lee is a postdoctoral research associate in the University of Maryland, U.S. He received the B.S. degree in Mechanical Design and Production Engineering from Yonsei University, Seoul, Korea, in 1998, and the M.S. and Ph.D. degree in Mechanical Engineering from KAIST (Korea Advanced Institute of Science and Technology), Korea, in 2000. His main research interests include structural shape and topology optimization, energy harvester design, nuclear plant design for hydrogen production, robust design using Taguchi method, genetic algorithm, automobile part and system design. He received the best paper award from Korean Society of Mechanical Engineering in 2007.