• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.40-43
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• 2008

High temperature polymer electrolyte membranes incorporating ionic liquids (ILs) in different polymers such as commercial fluorinated polymers, sulfonated polymers and recasted nafion have been developed. ILs based on imidazolium cation and different anions possess high ionic conductivity and good thermal stability and have been used in the present study. The membranes containing IL show conductivity ${\sim}10^{-2}S\;cm^{-1}$ above $100^{\circ}C$ under anhydrous conditions and are thermally stable up to $250-300^{\circ}C$. IL acts as a conducting medium in these electrolytes and plays the same role as played by water in fully hydrated nafion membranes. Due to high conductivity and good thermal stability, these membranes are promising materials for PEFCs at higher temperatures under anhydrous conditions.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.4
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• pp.350-355
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• 2005

소형 PEMFC(Proton Exchange Membrane Fuel Cell)는 전기를 만들기 위해서 고순도의 수소를 필요로 한다. 각각의 마이크로 성형된 금속박판(스테인레스 스틸, 알루미늄)을 진공 브레이징법으로 접합하여 수소공급용 소형 개질기를 제작하였다. 마이크로 채널의 내부는 졸-겔법(스테인레스 스틸)과 양극산화법(알루미늄)으로 촉매를 지지하기 위한 다공성 $Al_2O_3$ 층을 형성시켰다. 스테인레스 스틸 박판은 에칭과 브레이징에 유리하였으나, 표면산화층 코팅을 균일하게 하여 안정적인 촉매반응을 유도하기 위한 균일한 표면 산화층 형성이 힘들었다. 반면 알루미늄 박판은 표면 산화층 형성이 상대적으로 용이했으며, 촉매를 상하지 않는 낮은 온도에서의 적층이 가능했다.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3148-3153
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• 2008

Residential fuel cell cogeneration systems have gained much interest due to its high efficiency. In this study, we have performed numerical simulation of residential fuel cell cogeneration system which includes a fuel cell/grid hybrid system. The cogeneration system consists of 1kW PEFC, cooling system, inverter/converter and reformer. Several empirical models have been employed for respective components to improve the accuracy of the simulations. The load varies seasonally. The present simulations can successfully predict the characteristics of the hybrid cogeneration system and thus it can be utilized for establishing an optimal operating strategy of the system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.383-389
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• 2010

The vapor concentration of hexane in a liquid spray jet in crossflow was qualitatively measured on the basis of the infrared (IR) extinction techniques. The objectives of the present study are to understand the whole evaporation process from droplet breakup to vapor and to confirm the usefulness of IR emission method in a lab-scale ramjet combustor. From the experimental results, we concluded that hexane vapor mole fraction increased with temperature rise and kept nearly constant during the variation of fuel to air momentum ratio.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.197-198
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• 2007

본 논문에서는 연료전지 시스템에서 발생되는 저주파 리플의 전달과정을 분석하고, PCS 회로 및 인버터 제어방식에 따른 저주파 리플 영향을 비교 분석한다. 부스트 컨버터와 풀브리지 컨버터의 입력전류 고조파 분포와 인버터 PWM 스위칭 방식에 따른 입력전류에서의 영향을 고조파 분포 및 저주파 리플 측면에서 분석한다. 풀브리지 컨버터에서 전달되는 저주파 리플 크기가 상대적으로 작은 것을 확인하고, PWM 스위칭 방식은 저주파 리플에 영향을 주지 않는다는 것을 시뮬레이션을 통하여 확인한다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.199-200
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• 2007

본 논문은 연료전지 발전시스템 승압용 다상부스트 컨버터의 입력전류리플 크기를 수식화 하고 통류율 범위에 따른 다상부스트 컨버터의 상수 설계기법에 대해 제안한다. 제안된 다상부스트 컨버터는 평균전류제어를 적용하였으며 일반적인 부스트컨버터와 입력전류리플크기, 출력전압리플 크기를 시뮬레이션을 통해 비교 측정하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.4
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• pp.25-31
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• 2010

The vapor concentration of hexane in a liquid spray jet in crossflow was qualitatively measured on the basis of the infrared (IR) extinction techniques. The objectives of the present study are to understand the whole evaporation process from droplet breakup to vapor and to confirm the usefulness of IR emission method in a lab-scale ramjet combustor. From the experimental results, we concluded that hexane vapor mole fraction increased with temperature rise and kept nearly constant during the variation of fuel to air momentum ratio.

• Special Issue of the Society of Naval Architects of Korea
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• 2015.09a
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• pp.9-13
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• 2015

While environmental concern is urging shipbuilding industry to reduce pollutant emission, it is necessary to design environmental friendly vessels. LNG as fuel for ship propulsion is proven to be effective way to reduce pollutant emission. In this study, we find optimum position of LNG fuel supply system on AHTS by considering vessel characteristic. Three different positions of fuel supply system are studied in this paper. Factors such as stability, strength and safety are examined in each position of fuel supply system.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.3
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• pp.279-285
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• 2006

Recirculation for the unreacted fuel is necessary to improve the overall efficiency of the fuel cell system and to prevent fuel starvation since the fuel cell for a vehicle application is a closed system. In case of the automotive fuel cell, the ejector which does not require any parasitic power is good for the performance improvement and easy operation. It is essential to design the customized ejector due to the lack of the commercial ejector corresponding to the operating conditions of the fuel cell systems. In this study, the design methodology for the ejector customized to an automotive fuel cell is proposed. The model based sensitivity analysis prevents the time-consuming redesign and reduces the cost of developing ejector. As a result, the customized ejector to meet the desired performance within overall operating range has developed for the PEMFC automotive system.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.2
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• pp.104-115
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• 2009

In case of residential fuel cell system, it is significant to stably supply heat and power to a house with high efficiency and low cost for the successful commercialization. In this paper, the control strategy analysis has been performed to minimize the total cost including capital and operating cost of the residential fuel cell system. The proposed analysis methodology is based on the simulator including the efficiency models as well as the cost data for fuel cell components. The load control strategy is the key factor to decide the system efficiency and thus the cost analysis is performed when the fuel cell system is operated for several different load control logics. Additionally, annual efficiency of the system based on the seasonal load data is calculated since system efficiency is changeable according to the electric and heat demand change. As a result, the hybrid load control combined electricity oriented control and heat oriented control has the most economical operation.