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Nangen, South Korea

Kim C.-M.,Chosun University | Kim S.-C.,Seonam University | Shin S.-H.,Chosun University
New Microbiologica | Year: 2012

In Vibrio vulnificus, the production of metalloprotease VvpE is controlled by Crp (cAMP-receptor protein) and SmcR (a quorum sensing regulator) at the transcription level, and by PilD-mediated type II general secretion system (TTGSS) at the extracellular secretion level. Iron is known to stimulate VvpE production but the related mechanisms remain unidentified. Iron stimulated vvpE transcription and extracellular VvpE production even in the background with a crp and/or smcR mutation. Iron stimulated the transcription of pilD encoding an essential element of TTGSS. Therefore, iron seems to stimulate vvpE transcription through factor(s) other than Crp and SmcR, and to facilitate extracellular VvpE production by increasing the activity of TTGSS.

Park K.-H.,Chosun University | Kwak D.-H.,Seonam University
Journal of Electroanalytical Chemistry | Year: 2014

Electrosorption is a promising method for water purification and desalination. Activated carbon sheet (ACS) electrodes with commercially viable mechanical strength, electrosorption capacity, and electrochemical properties were fabricated, and their kinetic characteristics were determined. The ACS electrodes were obtained by coating activated carbon powder with 10 wt% polyvinylidene fluoride (PVdF) binder in a thin sheet-like formulation for the electrosorption process. The electrosorption and kinetic data were successfully described both Langmuir and potential-independent Langmuir isotherms, and pseudo-second-order model. The electrosorption efficiency of ACS electrodes prepared with 10 wt% PVdF was 91.6% at sodium chloride concentration and applied potential of 100 mg/L and 1.2 V, respectively. Thus, the performance of the ACS electrodes prepared in this study indicates that they are suitable for electrosorption applications. © 2014 Elsevier B.V. All rights reserved.

Park C.M.,Center Samjin Co. | Lee S.H.,Seonam University
Applied Physics Letters | Year: 2013

A metamaterial system with a refractive index of near zero for acoustic wave is realized. The designed system, which uses Helmholtz resonators, is analyzed using the equivalent circuit theory. Through the simulation and the experiment, we observed a large phase velocity in the metamaterial and a concentration of the energy density in the narrow normal waveguide directly coupled to the metamaterial. This is different to the metamaterial for the electromagnetic wave, because the concentration of energy density of the electromagnetic wave occurs in the metamaterial inside. The acoustic metamaterial system can be applied to the development of device for the acoustic energy concentrator and the acoustic filter. © 2013 AIP Publishing LLC.

Kim M.-S.,Korean Urban Regeneration Technology Institute | Kwak D.-H.,Seonam University
Water Science and Technology | Year: 2014

Microalgae have been regarded as a pollutant causing algal blooms in lakes or reservoirs but have recently been considered as a useful source of biomass to produce biofuel or feed for livestock. For the algae particle separation process, carbon dioxide (CO2), one of the main greenhouse gases, is dissolved into a body of water rather than being emitted into atmosphere. This study aims at determining the feasibility of CO2 bubbles as an algae particle separation collector in a flotation process and providing useful information for effective algae harvesting by describing optimal operating conditions of dissolved carbon dioxide flotation or dissolved air flotation. The first step is to develop a flotation model for bi-functional activity, algae control and algae harvesting at the same time. A series of model simulations is run to investigate algae particle separation possibilities such as an initial collision-attachment efficiency that depends upon separation characteristics due to an algae life cycle, including: pH, size distribution, zeta potential, cell surface charge, density, electric double layer, alkalinity, and so on. Based on the separation characteristics, conditions required to form flocculation are predicted in order to obtain the optimal flotation efficiency. © IWA Publishing 2014.

Park S.-J.,Chonbuk National University | Choi S.,University of Northern British Columbia | Kim E.-J.,Seonam University
Corporate Social Responsibility and Environmental Management | Year: 2012

Researchers have studied many variables to understand consumer behavior and the choices consumers make, with regard to environmentally friendly products. Past research has tried to find the relationships between socio-demographic variables and preferences for environmentally sustainable products. The findings, however, are still relatively mixed, especially those concerning income; previous results are far from being conclusive in that past studies have found income to be negatively, positively, and insignificantly related to green consumer choices. This study investigates why the previous empirical studies of income are so varied, and, using an empirical study, demonstrates that the inconsistency of earlier findings might come from the non-linear relationship between income variables and environmental concern. © 2011 John Wiley & Sons, Ltd and ERP Environment.

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