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Yoo S.G.,Seonam University | Seul N.-O.,Seonam University
Journal of Institute of Control, Robotics and Systems | Year: 2017

Currently, domestic nuclear power plants have been in operation for more than 20 years. The designed lifespan of these nuclear power plants is approaching their limit. Kori Unit 1 already extended its operation in 2014, even though its design life was already over. When evaluating whether the nuclear power plant is continuously operated, it is necessary to have a method for estimating the state of the Chlorosulfonated Polyethylene(CSPE) cable that is used for power, communication, and control lines. It is designed for more than 40 years of use under normal circumstances, but its service life may be affected by environmental factors such as temperature, radiation, etc. This paper proposes a method with which to predict the aging state based on the results of various physical analyses according to the CSPE cables' years of use. We predicted the aging state and applied a neural network method to implement the predicted life prediction algorithm based on the experimental results of the dielectric constant, apparent density, and elongation. The predictive performance was verified by a comparative experiment using a virtual degradation test specimen. © ICROS 2017.

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.

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 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 Y.S.,Kyung Hee University | Park Y.S.,Seonam University | Kim H.-K.,Seonam University
Thin Solid Films | Year: 2011

Aluminum-doped ZnO (AZO) thin-films were deposited with various RF powers at room temperature by radio frequency (RF) magnetron sputtering method. The electrical properties of the AZO film were improved with the increasing RF power. These results can be explained by the improvement of the crystallinity in the AZO film. We fabricated the organic thin-film transistor (OTFT) of the bottom gate structure using pentacene active and poly-4-vinyl phenol gate dielectric layers on the indium tin oxide gate electrode, and estimated the device properties of the OTFTs including drain current-drain voltage (I D-VD), drain current-gate voltage (ID-V G), threshold voltage (VT), on/off ratio and field effect mobility. The AZO film that grown at 160 W RF power exhibited low resistivity (1.54 × 10- 3 Ω•cm), high crystallinity and uniform surface morphology. The pentacene thin-film transistor using the AZO film that's fabricated at 160 W RF power exhibited good device performance such as the mobility of 0.94 cm2/V s and the on/off ratio of ∼ 10 5. Consequently, the performance of the OTFT such as larger field-effect carrier mobility was determined the conductivity of the AZO source/drain (S/D) electrode. AZO films prepared at room temperature by the sputtering method are suitable for the S/D electrodes in the OTFTs. © 2011 Elsevier B.V. All rights reseved.

Kwak D.-H.,Seonam University | Kim M.-S.,Seonam University
Separation Science and Technology (Philadelphia) | Year: 2013

This study conducted a series of tests and simulations to estimate collision-attachment efficiency using a trajectory analysis method, to evaluate model sensitivity due to major impact factors in designing and operating dissolved air flotation (DAF) for the various types of wastewaters, and to find the possibility of model application in determining the flotation efficiency of DAF. Collision-attachment efficiency between a bubble and a particle in the model is described by hydrodynamics related to stream function in Stokes' flow and surface forces based on a classic DLVO theory, encoded using Matlab language software, and performed numerical analysis using the 5th Runge-Kutta method. Model simulation examined the effects of two major factors, size and zeta potential, on collision-attachment efficiency during flotation and field experiment evaluated to model results. Both results from the simulation and field experiment indicated that the larger particles presented the better collision and removal efficiency and the effect of particle zeta potential on collision-attachment efficiencies was increased as the particle zeta potential increased from the negative domain to the positive domain. Therefore, the collision-attachment efficiency model using the trajectory analysis method may be used in estimating the flotation efficiency and in explaining its characteristics. © 2013 Taylor and Francis Group, LLC.

PURPOSE:: To evaluate the association between corneal endothelial cell density (ECD) and donor topical glaucoma medication use in an eye bank database. METHODS:: Raw eye bank data included 19,159 donors over the period July 2007 to May 2015. Free-text, donor medication lists were retrospectively searched for glaucoma medication. Exclusion criteria were age less than 40 years, history of eye surgery, endothelial trauma, guttae, and cell densities <1000 or >3300/mm. Analysis of covariance was used to test differences in cell density between groups while adjusting for age. Linear regression was used to test the correlation of independent interval variables while adjusting for age. RESULTS:: Twelve thousand one hundred fifty-seven donors were included in the final analysis; 134 were on topical glaucoma medication. The mean ECD for donors not on glaucoma medication and pooled donors on glaucoma medication was 2561 ± 348 and 2516 ± 320 cells/mm, respectively (P = 0.42). Subgroup analysis by medication class resulted in nonstatistically significant differences between ECDs of nonmedicated donors and donors on alpha agonists (P = 0.76), beta blockers (P = 0.90), carbonic anhydrase inhibitors (P = 0.13), cholinergics (P = 0.37), and prostaglandin analogs (P = 0.62). The number of glaucoma medication classes used by donors was not a statistically significant predictor of endothelial density (P = 0.298). CONCLUSIONS:: Donors on topical glaucoma medication do not have ECDs statistically significantly lower than donors not on medication. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.

Kwak D.-H.,Seonam University
Desalination and Water Treatment | Year: 2015

Scum is often found on the water surface of flocculation and sedimentation basin in water treatment plants, although water treatment facilities should always be in clean condition. A series of analytical experiments were conducted on the raw water and scum to investigate the cause and characteristics of scum formation in the Seokseong water treatment plant, which has been experiencing scum treatment problems. The measurements results in the field indicated that the raw water in the receiving well was oversaturated with dissolved oxygen by the pressure of the intake pumping and conveyance. The oversaturated oxygen triggered micro-bubbles because of the sudden decrease in surface tension that is caused by the coagulant dose. Observations of the experimental facilities revealed that bubbles are generated originally on the surface of a floc, and the flocs are acting as a nucleation of the bubble formation. The chemical composition of scum consists of various hydrophobic compounds, similar to the sludge in the sedimentation basin. These findings led us to conclude that with an exception of the nucleation of bubble formation, the mechanism of scum formation is similar to the particle separation of the flotation process in the water treatment plant. Therefore, scum formation may be prevented or reduced if excessive increase in pipeline pressure is avoided when mixing with air during processes of intake pumping and conveyance. © 2013, Balaban Desalination Publications. All rights reserved.

Shin H.-Y.,Seonam University
Journal of the Korean Medical Association | Year: 2016

Although the role of mass media as a communicator of health information has continuously expanded, some programs with incorrect health and medical information have negative impacts on television viewers. Public benefit, objectivity of information, and impartiality of effectiveness should be considered from the initial stage of program production in promoting public health. Furthermore, program producers, professional performers, medical associations and government organizations should redefine their roles and cooperation and setting up a mutual-assistance system is needed to produce good programs for health and medical information. © Korean Medical Association.

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