Biological treatment of wastewater produced during recycling of spent lithium primary battery

Wastewater produced during recycling of spent lithium primary battery was biologically treated with Acidithiobacillus ferrooxidans to decrease the pH and metal concentration. Since the wastewater contains high concentrations of Cr, Ni, and Li, the effects of these metals on the bacterial activity in a 9 K medium were also investigated. Samples of the medium with different metal concentrations were treated, and the oxidation ratio of Fe²⁺ ions was measured to examine the activity of bacteria. In the treatment of simulated wastewater, the presence of Cr and Ni ions with concentrations of 8000 g m^?3 and 13,000 g m^?3, respectively, did not inhibit the bacterial activity, whereas the oxidation ratio of Fe²⁺ ions was observed to be low in the medium when Li ion was present with a concentration at 5000 g m^?3. This observation suggested that at this concentration, Li ion suppressed the bacterial activity. In the case of treatment of real wastewater containing Cr, Ni, and Li, the oxidation ratio of Fe²⁺ to Fe³⁺ was observed to be low while the Fe concentration and pH decreased to 21,633 g m^?3 and 1.8, respectively. Thus, the wastewater produced during the recycling of spent lithium primary batteries can be effectively treated biologically for re-circulating in the recycling process.     

Measurement of heat/mass transfer at second stage vane endwall according to step heights

Journal of Mechanical Science and Technology - Recently, domestic gas turbines are primarily operated under partial loads. Hence, thermal expansion of components decreases, leading to a...     

A study on squeal noise reduction considering the pad shape of the disc brake system for urban railway vehicles

Journal of Mechanical Science and Technology - In this paper, to help reduce the squeal noise produced during the braking of urban railway vehicles, the shape of the disc brake pad was investigated...     

Disparities in exploitative and exploratory patenting performance across regions: Focusing on the roles of agglomeration externalities

We try to identify the determinants of regional variation in both exploitative and exploratory innovative competencies. Hereby, we focus on how a knowledge-creation mechanism with specialized externalities differs from one with diversified externalities. Innovative competence in the US is measured by local patenting performance; exploitative and exploratory patenting performances are distinguished by the degree of backward citation. Based on the extended knowledge-production function, including the two agglomeration externalities, our findings show that specialized externalities are associated with exploitation, while diversified externalities are positively related with both exploration and exploitation, regardless of industrial sectors.     

Measurement of zeta potential of macroscopic surfaces with Navier velocity slip exploiting electrokinetic flows in a microchannel

A method devised to measure the zeta potential of macroscopic surfaces with Navier velocity slip non-destructively exploiting electrokinetic flows in a microchannel. For an accurate as well as facile determination of zeta potential using this method, we need a simple relationship between zeta potential and streaming potential for electrokinetic flows in microchannels with consideration of the possibility of the Navier velocity slip. In the present investigation, we derive a semi-analytic formula for this relationship based on a one-dimensional modeling of electrokinetic flow in microchannels, which is as accurate as the numerical solution of the full governing partial differential equations. This formula is expected to allow accurate measurements of zeta potential of various macroscopic surfaces with Navier velocity slip.     

Conjoint analysis for luxury brand outlet malls in Korea with consideration of customer lifetime value

As Asian economies have grown rapidly, Asia has become a new leading market of the luxury goods industry. This paper used conjoint analysis (CA) for the optimal design of a luxury brand outlet mall to maximize the customer lifetime value (CLV). This approach complements a simple CA by considering CLV. The proposed approach is then applied to designing a suburban luxury brand outlet mall in Korea, a new concept to Korea. The results indicate that the optimal design for the outlet mall is the medieval European-style mall, with the linkage to Natural Tourism, which consists of the restaurants with delicious food and the stores with similar ratio between masstige and luxury brands.     

Intrinsic Kinetics of Chlorination of WO<Subscript>3</Subscript> Particles With Cl<Subscript>2</Subscript> Gas Between 973 K and 1223 K (700 °C and 950 °C)

Chlorination is one of the methods applied in extractive metallurgy for the treatment of minerals to obtain valuable metals, such as titanium and zirconium. The possibility of applying chlorination metallurgy to other metals such as tungsten was the major aim of this study. The kinetics of the chlorination of tungsten oxide (WO₃) particles has been investigated by thermogravimetry between 973 K and 1223 K (700 °C and 950 °C) and for partial pressures of chlorine ranging from 15 to 70 kPa. The starting temperature for the reaction of WO₃ with chlorine is determined to be about 920 K (647 °C). The influence of chlorine diffusion through the bulk gas phase and through the particle interstices in the overall rate was analyzed. In the absence of these two mass-transfer steps, a reaction order of 0.5 with respect to chlorine partial pressure, and an activation energy of 183 kJ/mol were determined. For tungsten oxide particles of less than 50-μm size, a complete rate expression has been obtained.     

Current work and future trends for sustainable buildings in South Korea

Korea, selected as a target nation of the second commitment period for the reduction of greenhouse gases by 2013, is making efforts to reduce the production of greenhouse gases in all industrial fields. In particular, Korea is working hard to prepare for measures on the national level to reduce energy consumption and to limit the creation of carbon dioxide in the construction industry, which is responsible for over 40% of all carbon dioxide production. In order to pursue sustainability in the construction industry, existing development-focused construction activities must be transformed via a new paradigm focusing on sustainable development through the adoption of sustainable policies by the government and the development and dissemination of sustainable construction technologies.For such reasons, this study examined sustainable policies, research, and education recently used in Korea to identify future trends in the sustainable construction industry toward which Korea should strive in terms of governmental policy, research, education, and projects.     

Aircore mechanism during draining based on influence of pressure difference and drain port diameter

An understanding of the mechanism of aircore phenomenon during draining is very important. In this study, numerical simulations were conducted for different pressurized and suction pressure water tanks, as well as for different drain port diameters, to explain and validate the proposed aircore mechanism. It was found that increasing the pressure at the top surface of the tank results in suppression of the aircore, whereas an increase in the suction pressure at the drain port outlet enhances the development of the aircore. For different drain port diameters, it was observed that the duration of the aircore during draining decreases with a decrease in the drain port diameter, and that the aircore is suppressed for a very small drain port diameter.