• Membrane Journal
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• v.33 no.1
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• pp.1-12
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• 2023

In this review, surface modification methods of hydrophobic poly(tetrafluoroethylene) (PTFE) membrane are introduced and their improved hydrophilicity results are discussed. Fluoropolymer based membranes, represented by PTFE membranes have been used in various membrane separation processes, including membrane distillation, oil separation and gas separation. However, despite excellent physical properties such as chemical resistance, heat resistance and high mechanical strength, the strong hydrophobicity of PTFE membrane surface has become a challenging factor in expanding its membrane separation application. To improve the separation performance of PTFE membranes, wet chemical, hydrophilic coating, plasma, irradiation and atomic layer deposition are applied, modifying the surface property of PTFE membranes while maintaining their inherent properties.

• Journal of Energy Engineering
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• v.17 no.2
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• pp.107-115
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• 2008

The numerical analysis of energy and material balance, and plant performance has been carried out when applying the heavy residual oil instead of heavy oil to the existing heavy oil power station. The performance analysis model has been constructed for A heavy oil power station in Korea, and the modeling results were compared with the design data in order to ensure the validity of the model, and further compared with the plant operation data. With the heavy residual oil, the simulation gave 315 MW in power output, which is higher than that of the heavy oil combustion, but the plant efficiency turned out to be lower. The sensitivity analysis of heat rate for the changes in cooling water and ambient temperature, flue gas recirculation and power output has provided valuable information for the optimal operation of the power station.

• The Korean Journal of Rheology
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• v.8 no.3_4
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• pp.215-225
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• 1996

평판형의 열가소성 수지를 유리전이온도 이상으로 가열한 다음 압력을 가함으로써 원하는 형상의 제품을 성형하는 열성형공정은 대상 수지가 큰 변형을 일으킬 뿐만 아니라 비선형적 거동을 보이게 된다. 따라서 수지의 변형거동 예측과 최적성형조건의 설정에 많은 어려움과 시행착오를 거치게 되는 바, 열성형 공정의 최적화를 위한 연구의 일환으로 원형 평판위 수지를 대상으로 수지의 부풀림 거동과 이에 따른 두께 분포를 예측할수 있는유한요 소법의 수치모사 알고리듬을 개발하고자 하였다. Piola-Kirchhoff 응력 텐서와 Green 변형 텐서 및 lagrangian 변형 텐서를 사용하여 평판상의 응력-변형에 대한 비선형의 에너지 수 지식을 수립하고 Newton-Raphson 반복수렴법을 이용하여 근사적으로 해석하였으며 수지의 유변학적 구성방정식으로는 neo-Hookean 모델, Mooney-Rivlin 모델 및 Ogden 모델등의 초탄성 모델을 사용하여 그결과를 비교하였다. 수치모사에는 두께가 매우 얇기 때문에 두께 방향의 응력변화를 무시할수 있는 membrane 가정을 도입한 2차원적 해석과 두께 방향의 응력 변화를 고려하는 3차원적 해석을 모두 수행하고 그 차이를 비교하였으며 3차원적 해석 의 경우에는 penalty법을 이용하여 비 압축성을 만족하였다. 일차적으로 내압을 받는 두꺼 운 원통계에 대한 수치모사 해석을 수행하고 완전해와 비교함으로써 개발된 수치모사 알고 리듬의 열성형 공정에의 적용 타당성을 검증하였으며 이를 이용하여 원형 평판의 자유부풀 림거동을 예측한 결과 Treloar 등의 실험결과와 잘 부합함을 확인하였다. 또 간단한 형상의 금형이 있는 경우와 반지름 방향으로의 온도변화에 따른 수지의 변형거동을 해석함으로써 실제 열성형 공정에서 요구되고 있는 성형품의 두께 분포를 균일하게 하기 위한 방안을 제 시하였다.

• Journal of Energy Engineering
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• v.2 no.3
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• pp.276-284
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• 1993

This study is to obtain some basic data which are prerequisite for the conceptual design of gasification process based on entrained-bed type gasifier. The Gibbs free energy minimization method is used to analyze the chemical equilibrium in the gasifier. The modeling results which consider the conventional mass balance and heat balance are compared with the experimental data published by Electric Power Research Institute. The analysis shows that the reaction in a entrained-bed gasifier is influenced mainly by the amount of oxidant, by the temperature of gasifier and by the type of coals.

• The Korean Journal of Rheology
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• v.10 no.2
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• pp.92-97
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• 1998

열잠재성 경화제인 N-benzylpyrazinium hexafluoroantimonate (BPH)를 이용하여 함 량에 따른 DGEBA계 에폭시 수지의 경화반응에서의 유변학적 특서 및 반응속도를 연구하 였다. 경화시의 활성화 에너지를 Barrett 방법을 이용한 동적 DSC 측정방법으로 조사 하였 다. DSC 실험 결과 BPH의 함량이 증가할수록 활성화 에너지는 감소함을 알수 있었다. Rheomter를 이용하여 DGEBA/BPH 계의 유변학적 특성을 등온경화와 tdmdhsrud화 조건하 에서 살펴보았다. BPH의 함량이 증가함에 따라 겔화점 도달시간 빠르게 나타나는데 이는 낮아진 활성화 에너지에 기인한 것으로 사료된다. 두 번째 damping 피크를 이용하여 유리 화점을 측정하여 Time-Temperature-Transformation (T-T-T) cure diagram을 작성한 결 과 열잠재성 경화제의 특성인 일정온도 이상에서 활성이 나타남을 확인할수있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.22-22
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• 2018

본 연구에서는 수문학적 가뭄을 분석하기 위해 두가지 지수를 개발하여 소개하고자 한다. 첫번째는, 물수지식을 기반으로 산정된 Water Budget-based Drought Index(WBDI)로 강우와 증발산의 차이를 이용하여 산정한다. 두 번째는 에너지 수지식을 기반으로 산정된 Energy-based Water Deficit Index(EWDI)로 에너지 수지 기반의 증발산, 태양복사에너지와 토양수분 등을 이용하여 산정한다. 두가지 지수 모두 인공위성 영상 자료를 활용하였다. WBDI 산정을 위한 강수량 자료는 Tropical Rainfall Measuring Mission(TRMM)과 Global Precipitation Mission(GPM)를 활용하였으며, 증발산 자료는 Moderate Resolution Imaging Spectroradiometer (MODIS) 자료를 활용하였다. EWDI 산정에 필요한 입력자료는 모두 MODIS 자료를 활용하였다. 산정된 두 가뭄지수의 수문학적 가뭄 분석을 위해 자연유출지점인 6개 지점을 선정하여 유출량 자료와 비교하였다. 유출량 자료를 활용하여 Error matrix 기법을 적용하여 두 수문학적 가뭄지수의 우리나라에서의 적용성을 파악하였다.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.3
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• pp.23-32
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• 2010

The purpose of this study is to quantify human energy budgets for different structures of outdoor spatial surfaces affecting thermal comfort, to analyze the impacts of tree shading on building energy savings, and to suggest desirable strategies of urban greenspace planning concerned. Concrete paving and grass spaces without tree shading and compacted-sand spaces with tree shading were selected to reflect archetypal compositional types for outdoor spatial materials. The study then estimated human energy budgets in static activity for the 3 space types. Major determinants of energy budgets were the presence of shading and also the albedo and temperature of base surfaces. The energy budgets for concrete paving and grass spaces without tree shading were $284\;W/m^2$ and $226\;W/m^2$, respectively, and these space types were considerably poor in thermal comfort. Therefore, it is desirable to construct outdoor resting spaces with evapotranspirational shade trees and natural materials for the base plane. Building energy savings from tree shading for the case of Daegu in the southern region were quantified using computer modeling programs and compared with a previous study for Chuncheon in the middle region. Shade trees planted to the west of a building were most effective for annual savings of heating and cooling energy. Plantings of shade trees in the south should be avoided, because they increased heating energy use with cooling energy savings low in both climate regions. A large shade tree in the west and east saved cooling energy by 1~2% across building types and regions. Based on previous studies and these results, some strategies including indicators for urban greenspace planning were suggested to improve thermal comfort of outdoor spaces and to save energy use in indoor spaces. These included thermal comfort in construction materials for outdoor spaces, building energy savings through shading, evapotranspiration and windspeed mitigation by greenspaces, and greenspace areas and volume for air-temperature reductions. In addition, this study explored the application of the strategies to greenspace-related regulations to ensure their effectiveness.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.104-108
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• 1998

Analysis of energy budget in Neomysis awatschensis exposed to PCB toxicity was carried out by measurement of bioassay, growth, oxygen consumption, nitrogen excretion at 10 and $20^{\circ}C$. Energy contents of the body, molted exoskeleton and eggs, which measured to understand used energy for growth, molt and oxygen consumption were 5.52cal/mg, 2.17 cal/mg and 6.15 cal/mg, respectively. Feeding energies at $10^{\circ}C$ were 3.755ca1 in control group and 3.420 cal at 2.0 ppb concentration, of them, $70.19\%$ and $67.53\%$ of their energies were assimilated. At $20^{\circ}C$, feeding energies were 5.998 cal in control group and 4.166 cal at 2.0 ppb concentration. The assimilation efficiency of the mysid estimated by ash-ratio method ranged between $11.5\~67.5\%$ and $73.4\~70.5\%$ with PCB toxicity at $10^{\circ}C$ and $20^{\circ}C$ respectively. Energy used by respiration of total assimilated energy was $45.18\%$ in control group and $62.27\%$ in 2.0 pub concentration at $20^{\circ}C$, and energy used by metabolism was high 2.0 ppb concentration than control group.

• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.342-343
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• 2006

• Korea Petroleum Association Journal
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• no.10 s.44
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• pp.18-18
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• 1984