• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.87.1-87.1
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• 2011

For commercial applications, MEA development must be optimized in order to achieve high performance and low cost. There are many factors that affect the performance of MEA. Especially, the optimization of the method for preparing catalyst layer has great effect on the performance of MEA. Various methods have been used to prepare the catalyst layer of MEA. Among them, spraying method has a merit in that catalysis lay can be prepared with very flexible changes in catalyst layer as well as in the solvent composition of catalyst ink. In addition, in order to reduce the time required for manufacturing catalyst layer, an effort has been made to change the nozzle size and injection pressure of spray system. Further, the operation condition of spray system was changed in various ways in an effort to prepare optimum catalyst layer of MEA. Having optimized the operation condition of spraying system, comprehensive and diverse experiments were carried out concerning various factors that affect the performance of MEA. The present research report describes the results of more sub-categorized and more detailed experiments about the important factors (Nafion$^{(R)}$ ionomer, Relative humidity) which have been shown in previous experiments to exert greater effect on the performance of MEA.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.85.1-85.1
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• 2011

In this study, Grafoil$^{TM}$ which has comparable electric resistance and chemical stability but is flexible, fragile, and cheap material was adopted as bipolar plates for proton exchange membrane fuel cell(PEMFC) having only one straight line flow channel. Because of its flexibility, pressurizations of cell with various pressures showed different operating characteristics compared to ordinary graphite-used PEMFC. While performances of both cells decreased as these were pressurized, investigation of ohmic and faradaic resistance by electrochemical impedance measurement indicated different tendency of change. Ohmic resistance of graphite-used cell increased with increasing pressure, which is reversed in Grafoil$^{TM}$-used cell. It is speculated that effective chemical reaction area is decreased with increasing pressure in case of graphite-used one, but because of flexible property of Grafoil$^{TM}$, gas diffusion layer in Grafoil$^{TM}$-used cell was well-activated. Different rate of change of faradaic resistances in both cells support this supposition. However, although optimum point of pressurization is found, it is required to investigate other operating conditions because of low performance compared to graphite-used cell.

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.819-826
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• 2011

The proton exchange membrane fuel cell (PEMFC) is regarded as the most promising alternative power sources for unmanned aerial vehicle (UAV) due to its high energy density and silent operation. Since there are many load changes during UAV flight, thermal management is one of the important factor for the performance of PEMFC. In order to reduce the UAV weight for the stable operation of UAV, thermal management system (TMS) studied in this work does not use the fan but use the air flowing into UAV by UAV flight. In order to develop the passive type heat exchanger (HEX) for 1kW PEMFC, four types of HEXs are fabricated and their cooling performances are compared. The parametric study on the cooling performance of HEXs has performed with the variation of operating parameters such as mass flow rates and inlet temperature of air and coolant. Type 4 has the best performance in every case. This study can be helpful to achieve the optimal design of HEX for PEMFC powered UAV.

• 전산구조공학
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• 제3권1호
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• pp.97-107
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• 1990

본 연구에서는 쉘구조물의 해석을 위한 개선된 degenerated 쉘유한요소를 제시하였다. 본 연구의 개선된 degenerated 쉘요소는 shear locking 해결에 우수한 결과를 보인 가정된 전단변형도를 사용하고, membrane locking 현상을 제거하기 위해 평면내 변형도의 구성시 감차적분을 행하며, 쉘요소자체의 거동을 보완하기위해 비적합 변위형을 선택적으로 추가하였다. 본 요소는 기존 degenerated 요소계열에서 가장 큰 문제점중의 하나인 locking 현상과 전달가능한 거짓영에너지모드가 발생하지 않으며, 조각시험도 통과한다. 본 개선된 쉘요소의 거동을 알아보기위해 다수의 예제시험을 행하였다. 수치시험결과 본 요소는 빠른 수렴성과 안정성을 보여준다.

• 설비공학논문집
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• 제19권1호
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• pp.86-93
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• 2007

The PEM (polymer electrolyte membrane) fuel cell is one of the promising fuel cell systems as a new small power generating device for automobiles and buildings. The optimal design of cooling plates installed between MEA (membrane electrode assembly) is very important to achieve high performance and reliability of the PEMFC because it is very sensitive to temperature variations. In this study, six types of cooling plate models for the PEMFC including basic serpentine and parallel shapes were designed and their cooling performances were analyzed by using three-dimensional fluid dynamics with commercial software. The model 3 designed by revising the basic serpentine model represented the best cooling performance among them in the aspect of uniformity of temperature distribution and thermal reliability, The serpentine models showed higher pressure drop than the parallel models due to a higher flow rate.

• 한국의류학회지
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• 제31권1호
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• pp.77-84
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• 2007

The purpose of this study was to investigate and to compare the performances of silicone laminated materials sold for swimming cap in market, to get the basic data for product development. We selected 4 specimens and tested their air permeability, waterproofness and breathability. We also tested the physical and mechanical properties of the specimens using KES system. Silicone-laminated material was not bursted on high hydraulic pressure since silicone membrane gave waterproofness while PU/Polyester substrate gave elasticity. It didn't have air permeability and breathability at all. Any toxic materials such as Formaldehyde, Deldrin, PCP, Amin, TDBPP were not detected in silicone-laminated material and other materials. Silicone-laminated material had higher stretchability with the low force but it had lower elastic recovery and shape stability comparing to PU laminated material. It had lower flexibility than PU laminated material. It had lower unrecoverable amount in shearing direction. Friction coefficient was higher in silicone-laminated material than PU laminated material due to its surface stickiness. It was compressed easily and its compression resiliency was higher with compared to PU laminated material.

• 한국식품과학회지
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• 제24권4호
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• pp.306-310
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• 1992

두부순물에 함유된 가용성 고형물의 제거를 위해 두부순물을 각 역삼투막의 최대 허용압력(CA 930 : 20bar, HR95, HR98 : 60bar)하에서 역삼투처리시 HR형막의 액투과속도는 CA형막에 비해 거의 유사한 수준 이상을 유지하였으며 HR98막의 경우 역삼투 처리온도가 $50^{\circ}C$일 때 $30^{\circ}C$에서의 경우에 비하여 액의 막투과속도가 28.4% 증가하였다. 순물의 pH 조절에 따른 여액의 막투과속도 비교시 pH에 따라 액의 막투과속도는 다소 차이를 보였지만 전반적인 속도면에서 볼때 막투과속도 향상에는 효과를 보이지 않았다. 순물의 가용성 고형물 함f량이 2.3 Brix일 때 CA930, HR95 및 HR98막을 투과한 여액의 COD값은 각각 3,763ppm, 64ppm 및 91ppm이었으며 순물의 pH를 7.0으로 조절하여 역삼투시 순물에 함유된 COD 값의 99.9%를 제거시킬 수 있었다.

• 멤브레인
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• 제24권3호
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• pp.231-239
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• 2014

아연공기전지의 분리막으로 사용하기 위한 Polyetherimide (PEI) 재질의 막을 제조하였다. 막의 제조는 상전이법을 통하여 이루어졌으며, 캐스팅 용액은 PEI, n-methylpyrolidone (NMP) 및 polyvinylpyrolidone (PVP)으로 이루어졌다. 제조한 분리막을 이용하여 아연공기전지를 제작하였다. 캐스팅 용액 내의 PEI 함량과 캐스팅 용액에 대한 PVP 첨가량이 분리막의 모폴로지, 기계적 강도와 이온전도도에 미치는 영향은 각각 SEM, 인장강도실험 및 임피던스 실험을 통하여 측정, 평가하였다. 아연공기전지의 전기화학적 성능은 정전류 방전실험을 통하여 측정하였다. 캐스팅 용액 중의 PEI 함량이 증가함에 따라 분리막의 기계적 강도는 증가하였으며, 캐스팅 용액에의 PVP 첨가는 분리막의 기계적 강도에 큰 영향을 미치지 않았다. 용액 내의 PEI 함량이 증가하면서 분리막의 이온전도도는 감소하였다. 용액에 PVP를 첨가하는 데에 있어서 첨가량 10 wt%까지는 첨가량의 증가에 따라 분리막의 이온전도도는 증가하였다. PVP 첨가량이 10 wt%에서 이온전도도는 0.1 S/cm의 최대값을 보인 후 추가의 첨가에 따라서는 이온전도도가 감소하였다. 분리막의 이온전도도는 공기아연전지의 용량에 큰 영향을 미쳤으며, 높은 이온전도도를 갖는 분리막으로 제조한 전지가 높은 용량을 보였다.

• 청정기술
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• 제29권1호
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• pp.71-75
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• 2023

다공성 결정물질(예: 금속유기골격체(Metal-Organic Framework, MOF), 제올라이트(zeolite))로 만들어진 다결정성 분리막의 선택도는 일반적으로 크기가 1 nm 혹은 그 이상으로 알려진 비선택적 결정 간 결함, 즉 결정립계의 존재 때문에 저하된다. 본 논문에서는 다결정성 MOF 분리막 위에 폴리다이메틸실록산(polydimethylsiloxane, PDMS)의 코팅이 결정립계를 캡핑하여 분리막의 선택도를 향상시키는데 효과적임을 증명하였다. 제안된 개념을 증명하기 위해서 in-situ 용매열 합성법을 통해 제조된 지르코늄 기반의 MOF의 일종인 UiO-66 분리막 위에 PDMS를 코팅한 후, 코팅 전후의 성능변화를 관찰하였다. PDMS 코팅 후 UiO-66 분리막의 CO₂/N₂ 단일 기체 분리 선택도는 6에서 14로 증가하였고, 동시에 CO₂ 투과도는 5700 GPU에서 33 GPU로 감소하였다. 선택도의 증가는 PDMS 코팅이 결정립계 결함을 효과적으로 메웠음을 의미하며, 동반된 투과도의 감소는 PDMS 코팅이 결함을 메우는 동시에 분리막 위에 연속적인 층을 형성하여 추가된 투과 저항에서 비롯되었다고 판단된다.

• 한국재료학회지
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• 제21권3호
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• pp.180-185
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• 2011

This study is aimed to increase the activity of cathodic catalysts for PEMFCs(Polymer Electrolyte Membrane Fuel Cells). we investigated the temperature effect of 20wt% Pt/C catalysts at five different temperatures. The catalysts were synthesized by using chemical reduction method. Before adding the formaldehyde as reducing agent, process was undergone for 2 hours at the room temperature (RT), $40^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$ and $100^{\circ}C$, respectively. The performances of synthesize catalysts are compared. The electrochemical oxygen reduction reaction (ORR) was studied on 20wt% Pt/C catalysts by using a glassy carbon electrode through cyclic voltammetric curves (CV) in a 1M H2SO4 solution. The ORR specific activities of 20wt% Pt/C catalysts increased to give a relative ORR catalytic activity ordering of $80^{\circ}C$ > $100^{\circ}C$ > $60^{\circ}C$ > $40^{\circ}C$ > RT. Electrochemical active surface area (EAS) was calculated with cyclic voltammetry analysis. Prepared Pt/C (at $80^{\circ}C$, $100^{\circ}C$) catalysts has higher ESA than other catalysts. Physical characterization was made by using X-ray diffraction (XRD) and transmission electron microscope (TEM). The TEM images of the carbon supported platinum electrocatalysts ($80^{\circ}C$, $100^{\circ}C$) showed homogenous particle distribution with particle size of about 2~3.5 nm. We found that a higher reaction temperature resulted in more uniform particle distribution than lower reaction temperature and then the XRD results showed that the crystalline structure of the synthesized catalysts are seen FCC structure.