• 한국세라믹학회지
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• 제42권10호
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• pp.665-671
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• 2005

LSGM is known to show very serious interfacial reaction with other unit cell components, such as electrode, electrode functional or buffering layers. Especially, the formation of very resistive LaSr$Ga_{3}$$O_{7}$ phase at the interface of an anode and an electrolyte is the most problematic one in LSGM-based SOFCs. In this study, we investigated the interfacial reactions in LSGM-based SOFCs under different unit cell configurations. According to the microstructural analysis on the interfacial layer between an electrolyte and its neighboring component, serious interfacial reaction zone was observed. From the electrical and electrochemical characterization of the cell, we found such an interfacial reaction zone not only increased the internal ohmic resistance but also decreased the OCV(Open Cell Voltage) of the unit cell, and thus consequently deteriorated the unit cell performance.

• 한국세라믹학회지
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• 제43권5호
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• pp.270-276
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• 2006

LSGM(($La_xSr_{1-x})(Ga_yMg_{1-y})O_3$) electrolyte is known to show very serious interfacial reaction with other unit cell components, especially with an anode. Such an interfacial reaction induced the phase instability of constituent component and deterioration of the unit cell performance, which become the most challenging issues in LSGM-based SOFCs. In this study, we fabricated LSGM($La_{0.8}Sr_{0.2}Ga_{0.83}Mg_{0.17}O_x$) electrolyte supported-type cell in order to avoid such interfacial problem by lowering the heat-treatment temperature of the electrode fabrication. According to the microstructural and phase analysis, there was no serious interfacial reaction at both electrolyte/anode and electrolyte/cathode interfaces. Moreover, from the electrochemical characterization of the unit cell performance, there was no distinct deterioration of the open cell voltage as well as an internal cell resistance. These results demonstrate the most critical point to be concerned in LSGM-based SOFC is either to find a proper electrode material which will not give any interfacial reaction with LSGM electrolyte or to properly adjust the processing variables for unit cell fabrication, to reduce the interfacial reaction.

• Journal of Biosystems Engineering
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• 제18권4호
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• pp.358-370
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• 1993

In Korea, fruit grading has been mainly done manually, and manual grading depends on human sense. Thus it is subjected to human error and is not always as consistent as would be desired. Therefore, a study on the development of fruit grader was initiated to improve the consistency of fruit grading. The sensitivity for fruit weight of the conventional spring type weight grader has a tendency to decrease by physical characteristics of spring which is used as a weight sensing unit. This study was carried out to develop weight measuring device for establishing the base of weight sensing unit of electronic weight grader. This device consists of a weight sensor using load cell, data acquisition system, and a microcomputer containing program to calculate fruit weight. The weight measuring device using load cell was developed to increase sensitivity of fruit weight. The result of this study showed that the weight sensing unit of electronic weight grader contributed to the improvement of performance of weight measuring device.

• 한국수소및신에너지학회논문집
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• 제3권2호
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• pp.63-69
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• 1992

2개의 단위전지를 제작하여 각각 산소와 공기를 산화제로 하여 조업하였다. 산소를 사용한 단위전지의 350시간 조업후의 개전압 강하는 30mV였고 내부저항도 증가하였다. 공기를 사용한 단위천지의 250시간 조업후의 개전압강하는 130mV였고 산소를 사용한 경우와는 개전압 차이는 90mV였다. 공기를 이용한 단위전지의 조업 성능을 향상시키기 위하여는 전해질의 공급방법과 전극의 물질전달특성에 관한 연구가 필요하다.

• 한국세라믹학회지
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• 제43권5호
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• pp.299-303
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• 2006

In this paper, anode supported SOFC with columnar structured YSZ electrolyte was fabricated via Electron Beam Physical Vapor Deposition (EBPVD) method. Liquid condensation process was employed for the preparation of NiO-YSZ substrate and the high power electron beam deposition method was used for the deposition of YSZ electrolyte film. Double layered cathode with LSM-YSZ and LSM was printed on electrolyte via screen-printing method and fired at $1150^{\circ}C$ in air atmosphere for 3 h. The electrochemical performance and the long-term stability of $5{\times}5cm^2$ single cell were investigated with DC current-voltage characteristics and AC-impedance spectroscopy. According to the investigation, $5{\times}5cm^2$ sized unit cell showed the maximum power density of around $0.76W/cm^2$ at $800^{\circ}C$ and maintained the stable performance over 400 h.

• 에너지공학
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• 제1권1호
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• pp.58-65
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• 1992

인산형 연료전지의 전극성능의 향상을 위해 Hot Pressing공정을 사용하여 Pt이 담지된 다공성 탄소전극(Pt/C)을 제조하였다. Hot pressing의 조건, 촉매층에서의 PTEE 함량을 변화시켜 제조한 Pt/C 전극의 전기화학적 산소환원특성 및 인산형 단위전지 성능특성을 비교하였다. 실험결과 Hot Pressing의 최적조건은 36$0^{\circ}C$, 10kg/$\textrm{cm}^2$이었다. 최대성능은 촉매층에 30wt%의 PTFE 함량을 가진 전극에서 얻어졌으며, 이때 백금의 이용율은 80%이었다. 단위전지의 성능측정 결과, hot pressing한 전극의 성능은 700㎷에서 200mA/$\textrm{cm}^2$이었으며 200시간동안 안정적인 성능이 유지되었다.

• 한국정보통신학회논문지
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• 제18권2호
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• pp.260-267
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• 2014

본 논문에서는 칩커패시터와 마이크로스트립 선로를 이용하여 LH 구조의 단위셀을 고안하고, 제안된 단위셀로부터 등가회로를 추출하여 단위셀의 제반 특성을 분석하였으며, 광대역 고역통과필터를 설계하는데 적용하였다. 이 필터는 고역통과 특성을 갖는 여러 개의 단위셀을 종속 연결하여 마이크로스트립 전송선에 구현하였으며, 그 성능은 0~2.18 GHz의 저지대역에서 62.9dB의 대역제거 특성과 3.0~12.75 GHz의 통과대역에서 1.17dB 이하의 삽입손실을 갖는다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.82.2-82.2
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• 2011

A channel design which is closely related with the mass transport overpotential is one of the most important procedures to optimize the whole fuel cell performance. In this study, three dimensional results of a numerical study for gas distribution in channels of a molten carbonate fuel cell (MCFC) unit cell for a 1kW class stack was presented. The relationship between the fuel and air distribution in the anode and cathode channels of the unit cell and the electric performance was observed. A charge balance model in the electrodes and the electrolyte coupled with a heat transfer model and a fluid flow model in the porous electrodes and the channels was solved for the mass, momentum, energy, species and charge conservation. The electronic and ionic charge balance in the anode and cathode current feeders, the electrolyte and GDEs were solved for using Ohm's law, while Butler-Volmer charge transfer kinetics described the charge transfer current density. The material transport was described by the diffusion and convection equations and Navier-Stokes equations govern the flow in the open channel. It was assumed that heat is produced by the electrochemical reactions and joule heating due to the electrical currents.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.326-329
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• 2005

Proton exchange membrane (PEM) should be sufficiently hydrated with proper water management to maintain a good ionic conductivity and performance of a PEM fuel cell. However. cathode flooding resulting from excess water can impede the transport of reactants and hence deteriorate the fuel cell performance. For the PEM fuel cell to be commercially viable as vehicle or portable applications, the flooding on the cathode side should be minimized during the fuel cell operation. In this study, visualization technique was applied to understand the cathode flooding phenomena on the cathode side of a PEM fuel cell. To this end. a transparent PEM unit fuel cell wi th an act ive area of $25cm^2$ was designed and manufactured to allow for the visualization of cathode channel with performance characteristics. Two-phase flow resulting from the electro-chemical reaction of fuel cell was investigated experimentally. The images photographed by CCD camera with cell operating temperatures $(30\~50^{\circ}C)$ were presented. Results indicated that the flooding on the cathode side first occurs near the exit of cathode channel. As the operating temperature of fuel cell increases. it was found that liquid water droplets tend to evaporate easily and it can have an influence on lowering the flooding level. It is expected that this study can effectively contribute to the detailed researches on modeling water transport of an operating PEM fuel cell including two-phase flow phenomena.

• 한국군사과학기술학회지
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• 제19권2호
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• pp.211-217
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• 2016

The fuel cell based auxiliary power unit (APU) is promising for power source of armed vehicles due to its silence and high efficiency. Especially, the on board hydrogen generation and fed to fuel cell system was core technology of this power system. In this study, we analyzed the performance of the Auto thermal reactor (ATR) that produce the hydrogen from the fuel, integrated High temperature polymer electrolyte fuel cell (HT-PEFC) by Aspen plus software. The fuel was designed as a n-dodecane for analysis of military fuel (JP-8).