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Effect of operating temperature using Ni-Al-ZrH<sub>2</sub> anode in molten carbonate fuel cell
서동호(Seo, Dongho),장성철(Jang, Seongcheol),윤성필(Yoon, Sungpil),남석우(Nam, Suk Woo),오인환(Oh, In-Hwan),임태훈(Lim, Tae-Hoon),홍성안(Hong, Seong-Ahn),한종희(Han, Jonghee) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
Fuel cell is a device that directly converts chemical energy in the form of a fuel into electrical energy by way of an electrochemical reaction. In the anode for a high temperature fuel cell, nickel or nickel alloy has been used in consideration of the cost, oxidation catalystic ability of hydrogen which is used as fuel, electron conductivity, and high temperature stability in reducing atmosphere. Most MCFC stacks currently operate at an average temperature of 650?C. There is some gains with decreased temperature in MCFC to diminish the electrolyte loss from evaporation and the material corrosion, which could improve the MCFC life. However, operating temperature has a strong related on a number of electrode reaction rates and ohmic losses. Baker et al. reported the effect of temperature (575 to 650?C). The rates of cell voltage loss were 1.4mV/?C for a reduction in temperature from 650 to 600?C, and 2.16mV/?C for a decrease from 600 to 575?C. The two major contributors responsible for the change in cell voltage with reducing operation temperature are the ohmic polarization and electrode polarization. It appears that in the temperature range of 550 to 650?C, about 1/3 of the total change in cell voltage with decreasing temperature is due to an increase in ohmic polarization, and the electrode polarization at the anode and cathode. In addition, the oxidation reaction of hydrogen on an ordinary nickel alloy anode in MCFC is generally considered to take place in the three phase zone, but anyway the area contributing to this reaction is limited. Therefore, in order to maintain a high performance of the fuel cell, it is necessary to keep this reaction responsible area as wide as possible, that is, it is needed to keep the porosity and specific surface area of the anode at a high level. In this study effective anodes are prepared for low temperature MCFC capable of enhancing the cell performance by using zirconium hydride at least in part of anode material.
공진 방사체 임피던스 측정을 이용한 고효율 안테나 회로 설계 연구
서동호(Dongho Seo),김용주(Yong Joo Kim),윤원상(Won-Sang Yoon),한상민(Sang-Min Han) 대한전기학회 2022 전기학회논문지 Vol.71 No.1
A new antenna design method with high efficient characteristics is proposed by measuring input impedance of a radiative resonator. By means of a simple de-embedding method, the resonant frequency and input impedance are measured for antenna resonators. Retaining the resonant antenna characteristics, an impedance-matched feedline can be designed. In order to verify the validation, the patch antenna has been implemented with the proposed method. From the experimental results, the proposed antenna design has presented well matching property, a higher antenna gain, and higher radiation efficiency, compared to a reference patch antenna implemented by a conventional design method.