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Long-term durability test for direct methanol fuel cell made of hydrocarbon membrane
Prabhuram, Joghee,Krishnan, N. Nambi,Choi, Baeck,Lim, Tae-Hoon,Ha, Heung Yong,Kim, Soo-Kil Elsevier 2010 International journal of hydrogen energy Vol.35 No.13
<P><B>Abstract</B></P><P>A long-term durability test has been conducted for a direct methanol fuel cell (DMFC) using the commercial hydrocarbon membrane and Nafion ionomer bonded electrodes for 500 h. Membrane electrode assembly (MEA) made by a decal method has experienced a performance degradation about 34% after 500 h operation. Cross-sectional analysis of the MEA shows that the poor interfacial contact between the catalyst layers and membrane in the MEA has further deteriorated after the durability test. Therefore, the internal resistance of a cell measured by electrochemical impedance spectroscopy (EIS) has considerably increased. The delamination at the interfaces is mainly attributed to incompatibility between polymeric materials used in the MEA. Furthermore, X-ray diffraction (XRD) analysis reveals that the catalyst particles have grown; thereby decreasing the electrochemical surface area. Electron probe micro analysis (EPMA) shows a small amount of Ru crossover from anode to cathode; and its effect on the performance degradation has been analyzed.</P>
Fabrication of MEA with hydrocarbon based membranes using low temperature decal method for DMFC
Krishnan, N.N.,Prabhuram, J.,Hong, Y.T.,Kim, H.J.,Yoon, K.,Ha, H.Y.,Lim, T.H.,Kim, S.K. Pergamon Press ; Elsevier Science Ltd 2010 International journal of hydrogen energy Vol.35 No.11
The membrane electrode assembly (MEA) with hydrocarbon (HC) based membranes made by a low temperature decal method has been investigated for the direct methanol fuel cells (DMFCs). The conventional low temperature decal (LTD) transfer method (comprised of three layers; viz., carbon, Nafion bonded electrodes and outer ionomer layers over the decal Teflon substrates) meant for the MEAs made of Nafion type membranes is suitably modified to use with hydrocarbon (HC) based membranes. The modification of conventional LTD method is effected by means of modulating the three-layered structure and optimizing other parameters to facilitate complete transfer of catalyst layers onto the HC membranes. The MEAs prepared by the modified LTD method have yielded 21 % higher DMFC performance compared to that of the MEAs produced by conventional LTD method. The structure and electrochemical properties of the MEAs have been analyzed by the field-emission scanning electron microscopy (FE-SEM) and the electrochemical impedance spectroscopy (EIS).
Micro- and Macro-Level Factors Determining Financial Performance of UAE Insurance Companies
SASIDHARAN, Soumya,RANJITH, V.K.,PRABHURAM, Sunitha Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.12
The research aims to analyze the firm-specific and macroeconomic factors that affect insurance company's financial performance. The research explores the variables that influence the financial performance of the United Arab Emirates (UAE)' insurance companies. The analysis for determining financial performance considers the following variables: the firm's age, retention ratio, capital adequacy, underwriting risk/loss ratio, financial-leverage, reinsurance dependency, and macro-economic factors such as GDP per capita, inflation rate considered as independent factors. The return-on-asset (ROA) is the key measuring indicator; it is regarded as the dependent variable for financial performance measures. The research focuses on secondary information obtained from insurance companies' financial statements. The researcher targeted 18 insurance companies listed on the UAE stock exchanges for study purposes. The research examines the overall factors that influence the financial performance of an insurance company. For analysis of data, software package of social sciences (SPSS version 20) is used. The studies used correlation and multiple linear regression analysis to determine financial performance and their effects. The analysis suggests that there are important and constructive relationships between the size, capital adequacy, and reinsurance dependency, while loss ratio, retention ratio, and financial leverage indicate a major negative relationship. And there's no link between GDP per capita and inflation.
조재형(Jae Hyoung Cho),김장미(Jang Mi Kim),황상엽(Joghee Prabhuram),안동준(Sang Youp Hwang),하흥용(Dong June Ahn),김수길(Heung Yong Ha),Soo-Kil Kim 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.10
본 연구에서는 저온 데칼 전사법을 이용하여 막 전극 접합체(Membrane Electrode Assembly, MEA)를 제조하였다. 제조된 MEA는 직접 메탄올 연료 전지(Direct Methanol Fuel Cell, DMFC)를 이용하여 성능 테스트를 하였다. 저온 데칼 전사법은 140℃의 낮은 온도에서 촉매 층을 데칼 기판에서 멤브레 인으로 전사시키고, 전사된 촉매 층의 표면에 형성되는 것으로 알려진 이오노머 스킨 층의 형성을 막기 위해 이오노머/촉매/카본/기판의 구조로 되어 있는 데칼 기판을 사용한다. 저온 데칼 전사법으로 제조된 카본 층이 있는 MEA의 DMFC 성능이 카본 층이 없이 데칼 전사법으로 제조된 MEA나 전통적인 고온 데칼 전사법으로 제조된 MEA, 또는 직접 스프레이 코팅법으로 제조된 MEA의 성능보다 높게 나온 것을 알 수 있다. 저온 데칼 전사법으로 제조된 MEA의 DMFC 성능이 향상된 것은 촉매 층 위에 이오노머 스킨이 형성되지 않아 반응물의 확산이 원활하게 이루어지기 때문이다. 이를 위한 특성 분석으로 EIS, CV를 측정하였다.