• Nuclear Engineering and Technology
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• v.41 no.1
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• pp.135-142
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• 2009

In this investigation, we prepared a 1 and 3-parallel serpentine single PEMFC, which has an active area of $100\;cm^2$ and a flow channel cross section of $1{\times}1mm$. Distribution and transport of water in a non-operating PEMFC were observed by varying flow types and the flow rates (250, 400, and 850 cc/min). This investigation was performed at the neutron imaging facility at the CO1d Neutron RAdiography facility (CONRAD), HMI, Germany of which the collimation ratio and neutron fluence rate are 250, $1{\times}10^{6}n/s/cm^2$, respectively. The neutron image was continuously recorded by a scintillator and lens-CCD coupled detector system every 10 seconds. It has been observed that although the distilled water was supplied into the cathode channel only, the neutron image showed a water movement from the cathode to the anode channel. The water at the cathode channel was completely discharged as soon as the pressurized air was supplied. But the water at the anode channel was not easily removed by the pressurized air except for the 3-parallel serpentine type with 850cc/min of air flow rate. Moreover, the water at the MEA wasn't removed for any of the cases.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.161-166
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• 2002

The ultrastructural characteristics of epidermis isolated from healthy and rusty ginseng roots(Panax ginseng) were observed by scanning electron microscopy (SEM), and the distribution profiles of inorganic elements were also examined by energy dispersive X-ray analysis (EDX). The epidermis of rusty ginseng was thick and cell walls were also severely disrupted whereas the epidermal image of healthy ginseng showed relatively thin, clear and rectangular structure. A high amount of rod-shaped bacteria was found in rusty ginseng and cells near bacteria were degraded. The bacterial density in epidermis of rusty ginseng was ranged from 2.9$\times$10$^{6}$ to 3.5 $\times$ 10$^{7}$ CFU/g fresh weight, while that of healthy ones was from 4.7$\times$10$^2$ to 1.2$\times$10$^3$CFU/g. Artificial inoculation of bacteria isolated from rusty ginseng induced similar symptom like rusty ginseng. The mineral contents inculding Al, Si and Fe were Higher in the epidermis of rusty ginseng, but K content was lower compared to healthy ones.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.2
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• pp.171-175
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• 1990

One thousand and seven hundreds and six soybean land reces and 103 wild soybeans of Korea, and 167 cultivars and 71 wild soybeans of exotic were analyzed using polyacrylamide gel electrophoresis to study the distribution of trypsin inhibitor phenotypes. The four ti/ti lines were observed only in Korean native land races. The Ti$\^$*/a allele of cultivar was found to be the highest in Chinese soybean (0,9888) than in Korean soybean(0.8347) and Japanese soybean (0.5954). The heterozygosity of typsin inhibitor in Korean lines occured in relatively high ratio, The percentages of heterozygosity of the Korean land race and wild soybean are 3.6% (N=61) and 9.7%(N=10), respectively.

• Applied Chemistry for Engineering
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• v.5 no.1
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• pp.139-148
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• 1994

The partial oxidation of methane with nitrous oxide on silica-supported metal-oxygen cluster compounds, known as heteropoly acids, has been studied. The effects of several variables such as reaction temperature, partial pressure of reactants, residence time, loading of the catalysts, and pretreatment temperature, on the conversion and product distribution were observed. The kinetics also has been studied. The conversion and yield of formaledehyde show maximum values at a loading of 20 wt%. The apparent reaction order of methane conversion is ca. 1.0 with respect to $CH_4$ and ca. 0.4 with respect to $N_2O$. In addition, the apparent activation energy is 30.78 kcal/mole. The addition of small quantities methane whereas water introduced to the reactant decreased the activity of catalyst under present study.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.975-983
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• 2011

A microfin on a heated surface and its effects of the heat transfer has been investigated. The thickness of the fin is about 8 micrometer to allow the flexible up-down motion of the fin. Two-way complete FSI (Fluid-Structure Interaction) method has been applied for the analysis. Firstly, the deformation of a microfin due to the pulsating flow is evaluated using structure analysis. The flow and temperature patterns are predicted by CFD (Computational Fluid Dynamics) method. At each time step, using the pressure force and temperature distribution from CFD, the deformation of the wing is evaluated by FEM. Also in order to estimate the resonance probability, the natural frequency of the wing structure is calculated by modal analysis. The proposed numerical procedure was validated through experiment using a single fin. Through this work, we show that the increase of 40% in heat transfer capacity using the microfin has been compared with that of flat plate case.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.497-500
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• 2007

지열류량은 지열자원 개발 시 지열 이상대를 찾는데 있어서 중요한 자료로 사용된다. 우리나라의 지체구조별 지열류량 평균은 경기육괴 66 $mW/m^2$, 옥천습곡대 65 $mW/m^2$, 영남육괴 60 $mW/m^2$, 경상분지 72 $mW/m^2$, 연일분지 75 $mW/m^2$이다. 이러한 대륙 내의 지표 지열류량은 상부 지각내의 방사성 동위원소 붕괴에 의한 열생산율(${\sim}40%$)과 하부지각 및 상부맨틀에서부터 전도되어 올라온 지열류량(${\sim}60%$)으로 설명할 수 있다. 따라서 지열류량의 결정에 있어서 열생산율의 정보는 중요한 부분을 차지한다. 열생산율은 지각 내에 존재하는 주요 방사성 동위 원소인 U, Th, K의 붕괴열에 의한 것이며, 열생산율의 측정은 gamma-ray log 자료를 이용하는 방법과 화학분석을 통한 방법이 있다. 이 연구에서는 두 가지 방법을 이용하여 총 123개(화강암 86개, 편마암 37개) 지점에서의 열생산율을 산출하였다. 화강암의 열생산율 평균은 2.15 ${\mu}W/m^3$이며, 편마암의 열생산율 평균은 2.22 ${\mu}W/m^3$로 나타났다. 지체구조별 열생산율의 평균은 경기육괴 2.52 ${\mu}W/m^3$, 옥천습곡대 2.16 ${\mu}W/m^3$, 영남육괴 2.35 ${\mu}W/m^3$, 경상분지 2.01 ${\mu}W/m^3$로 나타났다. 지체 구조별 열생산율과 지열류량의 상관성 분석에서 우리나라의 경우 지열류량이 높은 지역에서 열생산율이 낮은 경향을 보인다. 따라서 열생산율이 지표 지열류량을 결정하는데 있어서 가장 중요한 요소가 아님을 확인할 수 있다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.649-653
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• 2007

국제 원유가의 지속적인 상승에 따라 화석연료 고갈을 대비한 대체에너지 빛 온실가스배출감소를 위하여 바이오연료의 사용 및 상용보급은 전세계적인 추세이다. 우리나라의 경우 바이오디젤은 2002년부터 시범보급사업(Demonstration & dissemination)을 거쳐 2006년 7월부터 전국주유소를 통하여 경유 중에 바이오디젤 0.5%를 혼합한 BDO.5를 수송용 연료로 도입하여 아시아 최초로 상용보급화를 시행하고 있다. 또한 휘발유 중 바이오에탄올 혼합 연료유 도입을 위한 실증평가연구를 2006년 8월부터 2008년 7월까지 수행중이다. 자동차용 휘발유의 옥탄가 향상을 위해 함산소 기재로 사용되는 MTBE(Methyl Tertiary Butyl Ether)를 바이오에탄올로 대체한 바이오에탄올 혼합연료유는 수분 혼입에 의한 상 분리(Phase separation)와 금속에 대한 부식성 문제를 야기 시킬 수 있다. 바이오에탄올을 서브옥탄가솔린(Sub-octane gasoline)에 혼합하여 상 분리 모사실험, 금속류 부식시험, 고무류 침지실험 등 다양한 품질특성평가를 수행하였으며, 이런 결과들을 바탕으로 국내실정에 알맞은 최적의 혼합량(E3, E5)을 도출하였다. 또한 전국에 4개 시범주유소를 운영하여 바이오에탄올 혼합 연료유의 유통 및 보급을 통해 최적의 유통인프라(Distribution infrastructure) 보완 및 구축 방안을 도출 하고자 한다.

• Journal of the Korean Society for Nondestructive Testing
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• v.7 no.2
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• pp.42-47
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• 1988

The off-axis tensile strength of the unidirectional carbon fiber reinforced plastic and the residual strength of impact damaged CFRP were measured and compared with the stress wave factor (SWF) of the specimens. The SWF values were measured to be decreased with the strength reduction in both cases and found to be useful for the nondestructive strength evaluation of unidirectional CFRP. The failure behaviour of the unidirectional CFRP during off-axis tensile testing was also monitored by acoustic emission(AE) method. The AE energy release showed the characteristic feature depending on the off-axis angle and this result was analyzed to be caused by the difference of the expected failure mode depending on the off-axis angle. The failure mode of CFRP was found to be analyzed by investigation of the peak amplitude distribution of AE.

• Progress in Superconductivity
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• v.6 no.2
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• pp.133-137
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• 2005

We fabricated the Au/Ni template for YBCO coated conductors and evaluated texture formation and the microstructural evolution. The cube textured Ni substrate was fabricated by rolling and recrystallization annealing, and subsequently Au layer formed on the substrate by electroless-plating method. The texture was evaluated by pole-figure with x-ray goniometer with orientation distribution function (ODF) analysis. The surface roughness and grain boundary morphology of template were characterized by atomic force microscopy (AFM) We observed that Au layer deposited epitaxially on Ni substrate and formed a strong cube texture when plating time was optimized. The full-width at half-maximum (FWHM) was $8.4^{\circ}$ for out-of-plane and $9.98^{\circ}$ for in-plane texture for plating time of 30 min. Microstructural observation showed that the Au layer was homogeneous and dense without formation of crack/microcrack. In addition, we observed that root-mean-square (RMS) and depth of grain boundary were 14.6 nm and 160 $\AA$ for the Au layer, respectively, while those were 27.0 nm and 800 $\AA$ for the Ni substrate, indicating that the electoless-plated Au layer had relatively smooth surface and effectively mollified grain groove.

• Journal of Korean Society of Steel Construction
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• v.23 no.5
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• pp.595-606
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• 2011

This study was conducted to investigate the seismic behavior of steel member resisting frames considering the relative stiffness of the connection and beams. Six-story steel moment frames were designed to study the seismic behavior. The connections were classified into Double Web-Angle connections (DWAs), Top- and Seat-angles with double Web-angles (TWSs), FEMA-Test Summary No. 28, Specimen ID: UCSD-6 (SAC), and Fully Restrained (FR). The rotational stiffness of the semi-rigid connections was estimated using the Three-Parameter Power Model adopted by Chen and Kishi. The relative stiffness, which is the ratio of the rotational stiffness of the connections to the stiffness of the beams, was used. Push-over, repeated loading, and time history analysis were performed for all the frames. The seismic behavior of each frame was analyzed with the story drift, plastic hinge rotation, and hysteretic energy distribution.