Preparation and characterizations of interpenetrating polymer network hydrogels of poly(ethylene oxide) and poly(methyl methacrylate)

Interpenetrating polymer network (IPN) hydrogels based on poly(ethylene oxide) and poly(methyl methacrylate) were prepared by radical polymerization using 2,2‐dimethyl‐2‐phenylacetophenone and ethylene glycol dimethacrylate as initiators and crosslinkers, respectively. The IPN hydrogels were analyzed for sorption behavior at 25°C and at a relative humidity of 95% using dynamic vapor sorption. The IPN hydrogels exhibited a relatively high equilibrium water content in the range of 13–68%. The state of water in the swollen IPN hydrogels was investigated using differential scanning calorimetry. The free water in the hydrogels increased as the hydrophilic content increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 258–262, 2003     

Code-to-code comparison study on rotor aeromechanics in descending flight

This paper conducts the aeromechanics study using the two different rotorcraft computational structural dynamics (CSD) codes, CAMRAD II and DYMORE II, for the rotor in low-speed descending flight. The three test cases of the HART (Higher-harmonic control aeroacoustic rotor test) I -baseline, minimum noise, and minimum vibration- are considered in this study of the blade-vortex interaction (BVI) airloads, rotor trim, blade elastic deformations, and blade structural loads. The two prediction results are compared to each other for a code-to-code comparison study as well as to the measured data. Although CAMRAD II and DYMORE II use different theories and models, most of the prediction results are similar to each other and compared fairly well with the wind tunnel test data. For all the three test cases, the two rotorcraft CSD analyses show good prediction on the fluctuations of the section normal force (M²C_n) due to BVI, but both over-predict the trimmed collective pitch angle. The blade elastic deformations, such as flap deflection and elastic torsion deformation at the tip, are reasonably predicted by both rotorcraft CSD analyses. But, the CAMRAD II result using the multiple-trailer wake model with consolidation is slightly better than the DYMORE II prediction with the single wake panel model particularly for the elastic torsion deformation in the baseline case. In addition, CAMRAD II and DYMORE II both correlate reasonably the blade structural loads, such as flap bending, lead-lag bending, and torsion moments, with the measured data; however, the CAMRAD II results are moderately better than the DYMORE II predictions.     

Automatic generation and refinement of hypertext links

Abstract

Current generation of hypertext systems suffer from the limitations that they are static in nature, and they do not support the automated process of link creation very well. Because of the efforts involved in manually creating links, the hyperbases created using these systems are seldom modified even when they were found not to fully support the requirements of the intended users. This paper studies the development of automated tools to aid in the process of link creation, browsing, and link refinement. Only relation links are considered in this study. The automated tools are developed to help in three of the major stages of developing and using hypertext applications: (a) during authoring to generate a set of relation links between pairs of nodes; (b) during browsing to recommend an optimal set of starting nodes for the users to begin browsing, and to guide the users at each stage of browsing by suggesting a set of “next” nodes to traverse; and, (c) during training to modify, remove and add links based on users' feedback data collected. The training will result in long-term changes in the hypertext structure.

In order to test the effectiveness of the training process objectively, a navigator is built to simulate the browsing activities of the users. The effects of training have been evaluated on two text collections using a variety of objective measures. The results indicate that the training process has improved the effectiveness of the hyperbase to support browsing.     

Effect of deposition temperature on dielectric properties of PECVD Ta2O5 thin film

Tantalum oxide film formation by plasma-enhanced chemical vapour deposition (PECVD) using TaCl₅ as a source material was examined. The effects of deposition temperature on the formation, structure and electric properties of the Ta₂O₅ film were investigated for Al/Ta₂O₅/ p-Si (MTS) capacitors. The deposition rate and refractive index increased with increasing deposition temperature. It was found that the structure of Ta₂O₅ deposited by PECVD was amorphous as-deposited. However, crystalline -Ta₂O₅ of hexagonal structure was formed by a 700 °C, 1 h heat treatment in argon. Capacitance and relative dielectric constant of the PECVD Ta₂O₅ were found to be 2.54 fF m^–2 and 23.5, respectively. The PECVD films obtained in this study have higher dielectric constants and remarkably better general film characteristics than those obtained by other deposition methods.     

On burst rescheduling in OBS networks with partial wavelength conversion capability

The core nodes in an optical burst switching (OBS) network are normally equipped with wavelength converters (WCs) to reduce the burst loss probability. Since WCs are expensive and still immature technologically, it is desirable to reduce the number of WCs in the network and to have partial wavelength conversion capability at the core nodes. Nevertheless, a majority of algorithms in the literature are proposed under the full wavelength conversion assumption. As a result, they do not consider the burst loss caused by insufficient WCs, i.e., bursts dropped due to the unavailability of free WCs to convert them to unused wavelengths. In this paper, we demonstrate how to use burst rescheduling to decrease the burst loss due to insufficient WCs and hence cut down on the overall burst loss probability in OBS networks. Two burst rescheduling algorithms are proposed. Their effectiveness in reducing the overall burst loss probability is verified through simulation experiments.     

Accurate online video tagging via probabilistic hybrid modeling

Accurate video tagging has been becoming increasingly crucial for online video management and search. This article documents a novel framework called comprehensive video tagger (CVTagger) to facilitate accurate tag-based video annotation. The system applies both multimodal and temporal properties combined with a novel classification framework with hierarchical structure based on multilayer concept model and regression analysis. The advanced architecture enables effective incorporation of both video concept dependency and temporal dynamics. Using a large-scale test collection containing 50,000 YouTube videos, a set of empirical studies have been carried out and experimental results demonstrate various advantages of CVTagger over the state-of-the-art techniques.     

Examining the Effectiveness of Gamification in Human Computation

Within the human computation paradigm, gamification is increasingly gaining interest. This is because an enjoyable experience generated by game features can be a powerful approach to attract participants. Although potentially useful, little research has been conducted into understanding the effectiveness of gamification in human computation. In this experimental study, we operationalized effectiveness as perceived engagement and user acceptance and examined it by comparing the performance of a gamified human computation system against a non-gamified version. We also investigate the determinants of acceptance and how their effects differ between these two systems. Analysis of our data found that participants experienced more engagement and showed higher behavioral intentions toward the gamified system. Moreover, perceived output quality and perceived engagement were significant determinants of acceptance of the gamified system. In contrast, determinants for acceptance of the non-gamified system were perceived output quality and perceived usability.     

Legal system and its effect for prevention of work-related musculoskeletal disorders in Korea

This study aims to introduce the legislation of occupational safety and health regulations for prevention of WMSDs in Korea and investigate its effect by showing an ergonomic intervention effort in a major motor company. In Korea, WMSDs incidence rates had increased from 1999 to 2003, and it is noted that its increment jumped rapidly in 2002 and 2003. The Korean government established a law prescribing employers’ duty of preventing WMSDs in 2002, which began effective in July, 2003. Following the legislation, all employers should execute the examination of WMSDs risk factors for the eleven designated tasks every three years. In addition to this legal obligation, some large companies voluntarily established an ergonomic intervention program by carrying out in-depth assessments for stressful tasks using OWAS, RULA, NLE, etc. We introduce a major motor company case to illustrate the industry’s activities of fulfilling the legislative requirement and of performing ergonomic assessments. Thanks to Korean government and industry’s effort for prevention of WMSDs, the incidence rates of WMSDs have continually decreased from the year of 2004, right after the year when the WMSDs-related regulation was enforced.

Relevance to industry

In spite of booming of information technology industries and automation of manufacturing processes in Korea, many workers are still exposed to the risk of WMSDs including awkward postures, stressful force exertions, repetitive motions in manufacturing and agriculture industries. WMSDs cases alone constitute 43.1% of occupational diseases in Korea and the industry’s effort of ergonomic intervention of WMSDs becomes a major issue to both the management and the labor union.