• The Bulletin of The Korean Astronomical Society
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• 제41권2호
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• pp.64.1-64.1
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• 2016

We study the evolution of a late-type galaxy (LTG) in a rich cluster environment by using N-body/SPH simulations. To do that we perform a set of simulations of a LTG falling in a Coma-like cluster and also the LTG colliding with early-type galaxies (ETGs) multiple times in the cluster environment. We use a catalog of the Coma cluster in order to estimate the typical number of collisions and the closest approach distances that a LTG would experience in the cluster. We investigate the cold gas depletion and star formation quenching of our LTG model influenced by the hot cluster gas as well as the hot halo gas of the colliding ETGs.

• Journal of Advanced Marine Engineering and Technology
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• 제33권5호
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• pp.770-777
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• 2009

The energy depletion and the environmental pollution like global warming are worldwide issues. For correcting these problems there are many studies on new-renewable energy in Korea. A kind of new-renewable energy, PEMFC(Proton Exchange Membrane Fuel Cell) is a low temperature fuell cell and there are some cases of small craft or submarine adopted PEMFC system in maritime. PEMFC's performance is affected the operating conditions. Finding optimum operating conditions must be performed before adopting PEMFC to system. So in this study, we experiment about various operating conditions to apply 150W PEMFC stack for a model boat. And through the results, we find optimum operating conditions and study an effect of operating conditions to PEMFC.

• Korean Journal of Veterinary Research
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• 제36권3호
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• pp.571-575
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• 1996

Sulfamethazine sodium was orally administrated to Sprague Dawley female rats(body weight: 200~250g) with the sonde caude at the dose of 20mg of sulfamethazine sodium per 100g of body weight for 3 days to investigate the depletion rate of the drug from liver, kidney and muscle of rat. The results obtained were summerized as follows; 1. The mean concentrations of sulfamethazine in liver according to the time lapsed after oral administration of the sulfamethazine sodium were decreased from 1.27ppm at day 1 to 0.28ppm at day 4. 2. Sulfamethazine concentrations in kidney according to the time lapsed after oral administration of the sulfamethazine sodium were decreased from 0.77ppm at day 1 to 0. 12ppm at day 4. 3. The mean concentration of sulfamethazine in skeletal muscle according to the time lapsed after oral administration of the sulfamethazine sodium was at or below 0.09ppm within 4 days after withdrawl of medicated solution.

• Journal of the Korean Ceramic Society
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• 제55권4호
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• pp.307-324
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• 2018

Rechargeable lithium-ion batteries (LIBs) have been rapidly expanding from IT based applications to uses in electric vehicles (EVs), smart grids, and energy storage systems (ESSs), all of which require low cost, high energy density and high power density. The increasing demand for LIBs has resulted in increasing price of the lithium source, which is a major obstacle to wider application. To date, the possible depletion of lithium resources has become relevant, giving rise to the interest in Na-ion batteries (NIBs) as promising alternatives to LIBs. A lot of transition metal compounds based on conversion-alloying reaction have been extensively investigated to meet the requirement for the anodes with high energy density and long life-time. In-depth understanding the electrochemical reaction mechanisms for the transition metal compounds makes it promising negative anode for NIBs and provides feasible strategy for low cost and large-scale energy storage system in the near future.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제11권1호
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• pp.125-132
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• 1999

Studies are being done to replace conventional refrigerants with alternatives that have low or no ozone depletion and greenhouse warming Potentials, yet possess appropriate pro perties for a refrigeration cycle. To achieve this goal, a consistent set of thermodynamic properties of the working fluid is required. A common problem with the possible alternative refrigerants is that sufficient experimental data do not exist, thus making it difficult to develp complete equations of state that can predict properties in all regions including the vapor-liquid equilibrium. One solution is the use of the generalized equation of state correlations that can predict thermodynamic properties with a minimum number of characteristic parameters. Characteristic parameters required for the generalized equation of state are, in general, critical temperature, critical pressure, critical volume and normal boiling temperature. In this study, estimation of these characteristic parameters of refrigerants by group contribution method is developed.

• Environmental Analysis Health and Toxicology
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• 제16권1호
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• pp.9-16
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• 2001

It is known that alcoholics have significantly lower mitochondrial aldehyde dehydrogenase (ALDH)s'activity than do normal subjects or nonalcoholics with liver disease. However, there are only few reports that explain the reasons behind this reduction of ALDHs'activities. In this study, ALDH activity is inhibited by acetaldehyde, a substrate for ALDH However, the addition of glutathione (GSH) protected ALDH activities against the inhibitory effects of acetaldehyde in vitro. Furthermore, when GSH depletion is induced using diethyl maleate (DEM) in rats by 24% in cytosol and 43% in mitochondria, ALDH activities were also depressed by 31% and 63%, respectively compared to non-treated rats without significant reductions in other hepatic enzymes. These results suggest that ALDHs'activities are closely related to the concentration of acetaldehyde and/or cellular GSH contents . Therefore in alcoholic liver disease, increased productions of acetaldehyde and decreased contents of mitochondrial GSH may involved in the depression of ALDHs'activities.

• Advances in materials Research
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• 제4권2호
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• pp.63-76
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• 2015

The energy crisis involving depletion of fossil fuel resource is not the sole driving force for developing renewable energy technologies. Another driving force is the ever increasing concerns on the air quality of our planet, associated with the continuous and dramatic increase of the concentration of greenhouse gas (mainly carbon dioxide) emissions. The internal combustion engine is a major source of distributed $CO_2$ emissions caused by combustion of gasoline derived largely from fossil fuel. Another major source of $CO_2$ is the combustion of fossil fuels to produce electricity. New technologies for generating electricity from sources that do not emit $CO_2$, such as water, solar, wind, and nuclear, together with the advent of plug-in hybrid electric vehicles (PHEV) and even all-electric vehicles (EVs), offer the potential of alleviating our present problem. Therefore, the relevant technologies in $LiFePO_4$ as cathode material for Li-ion batteries suitable to the friendly environment are reviewed aim to provide the vital information about the growing field for energies to minimize the potential environmental risks.

• Journal of the Korean Vacuum Society
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• 제16권5호
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• pp.359-365
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• 2007

In this paper we present a bottom-gate type of zinc oxide (ZnO) and Gallium (Ga) doped zinc oxide (GZO) based thin film transistors (TFTs) through applying a radio frequency (RF) magnetron sputtering method at room temperature. The gate leakage current can be reduced up to several ph by applying $SiO_2$ thermally grown instead of using new gate oxide materials. The root mean square (RMS) values of the ZnO and GZO film surface were measured as 1.07 nm and 1.65 nm, respectively. Also, the transmittances of the ZnO and GZO film were more than 80% and 75%, respectively, and they were changed as their film thickness. The ZnO and GZO film had a wurtzite structure that was arranged well as a (002) orientation. The ZnO TFT had a threshold voltage of 2.5 V, a field effect mobility of $0.027\;cm^2/(V{\cdot}s)$, a on/off ratio of $10^4$, a gate voltage swing of 17 V/decade and it operated in a enhancement mode. In case of the GZO TFT, it operated in a depletion mode with a threshold voltage of -3.4 V, a field effect mobility of $0.023\;cm^2/(V{\cdot}s)$, a on/off ratio of $2{\times}10^4$ and a gate voltage swing of 3.3 V/decade. We successfully demonstrated that the TFTs with the enhancement and depletion mode type can be fabricated by using pure ZnO and 1wt% Ga-doped ZnO.

• Journal of the Korean Solar Energy Society
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• 제26권2호
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• pp.9-18
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• 2006

In this paper, the thermodynamic performance of OTEC cycle was examined. Computer simulation programs were developed for simple Rankine cycle, regenerative Rankine cycle, Kalina cycle, open cycle and hybrid cycle. For the simple Rankine cycle, the results show that newly developed fluids such as R410A and R32 that do not cause stratospheric ozone layer depletion perform as well as R22 and ammonia. Also, simple Rankine cycle OTEC power plant can practically generate electricity when the difference in warm and cold sea water inlet temperatures are greater than $14^{\circ}C$. The regenerative Rankine cycle showed a 1.5 to 2% increase in energy efficiency compared to the simple Rankine cycle while the Kalina cycle employing ammonia/water mixture showed a 2-to-3% increase in energy efficiency, and the overall cycle efficiencies of hybrid cycle and open cycle were 3.35% and 4.86%, respectively.

• Journal of the Korean Solar Energy Society
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• 제30권3호
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• pp.124-130
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• 2010

Ocean Thermal Energy Conversion(OTEC) power plants have been examined as a viable option for supplying clean energy. This paper evaluated the thermodynamic performance of the OTEC Power system for the production of electric power and desalinated water. The results show that newly developed fluids such as R32, R125, R143a, and R410A that do not cause stratospheric ozone layer depletion perform as well as R22 and ammonia. Overall cycle efficiency of open cycle is the lowest value of 3.01% because about 10% of the gross power is used for pumping out non-condensable gas. Also, the hybrid cycle is an attempt to combine the best features and avoid the worst features of the open and closed cycles. The overall cycle efficiency of hybrid cycle is 3.44% and the amount of desalinated water is 0.0619 kg/s.