• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.101-104
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• 2007

Mechanical behavior in metal bipolar plate of a fuel cell stack was studied using finite element analysis. The fuel stack is essentially composed of a metal bipolar plate (metal BP), a gasket, an end plate, a membrane electrolyte assembly (MEA), and a gas diffusion layer (GDL). It is important to maintain a suitable fastening force of Metal BP, because it influences the power efficiency of the fuel cell stack. After a gasket and a GDL are placed on the metal BP, the reaction force with the displacement is measured. The channel of metal bipolar plate is replaced by a simple geometrical plate. The results of FEM are similar to those of experiment. Therefore mechanical behavior in metal BP of a fuel cell stack can be estimated by using FEM.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.2
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• pp.157-166
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• 1985

The Purpose of this study are to investigate the characteristics of the flame behavior of gasoline-methanol blended fuels in spark ignition engine. Ionization probe were installed at the cylinder head and piston in order to measure flame speed. Other parameter such as engine performance, fuel consumption rate and exhaust gas were measured. The results were as follows. 1. In the case of increase methanol contents in blend fuel, flame propagation speed were increased, and thermal efficiency of the engine were increased due to decrease of energy consumption rate. 2. In the case of fixed equivalance ratio, NO sub(X) in exhaust gas were increased in accordance with increase of spark advance, and mean effective pressure were decreased in accordance with increase of methanol contents. 3. CO and HC concentration were decreased in accordance with increase of methanol contents.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.4
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• pp.1-9
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• 2010

Fuel shutoff valve of a gas generator controls propellant mass flowrate of a rocket engine, by using pilot pressure and spring force. The developing fuel shutoff valve can be self sustained even though pilot pressure is removed in an actuator. Therefore, it is necessary to analyze the characteristics of the forces with respect to the opening and closing of the valve in order to evaluate its performance. In light of this, the valve has been designed to adjust the control pressure for the opening of the poppet and to determine the working fluid pressure at which the valve starts to close. This paper also has been designed dynamic model using the AMESim and predicted flow coefficient of the valve by Fluent CFD analysis. Various results from the prediction and the analysis have been compared with experiments. Finally, dynamic characteristics of the valve have been verified with experimental results.

• Journal of Aerospace System Engineering
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• v.18 no.3
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• pp.8-16
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• 2024

Because hydrogen has very low density, a different storage method is required to store the same amount of energy as fossil fuel. One way to increase the density of hydrogen is through liquefaction. However, since the liquefied temperature of hydrogen is extremely low at -252 ℃, it is easily vaporized by external heat input. When liquid hydrogen is vaporized, a self-pressurizing phenomenon occurs in which the pressure inside the hydrogen tank increases, so when designing the tank, this rising pressure must be carefully predicted. Therefore, in this paper, the internal pressure of a cryogenic liquid fuel tank was predicted according to the liquid hydrogen filling ratio. A one-dimensional thermodynamic model was applied to predict the pressure rise inside the tank. The thermodynamic model considered heat transfer, vaporization of liquid hydrogen, and fuel discharging. Finally, it was confirmed that there was a significant difference in pressure behavior and maximum rise pressure depending on the filling ratio of liquid hydrogen in the fuel tank.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.8
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• pp.740-746
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• 2008

In this paper, robust structural design of the PEMFC stack gasket is pursued with Taguchi method by considering the noise factor in stack assembly. The study of noise problem in stacking is required to secure the safety and performance improvement of PEMFC stack. The design parameters in the Taguchi method are selected so that the structural responses are insensitive to the noise factors. In the gasket analysis, a Mooney-Rivlin strain energy function is used to consider hyperelasticity between load and displacement. By uni-axial and equi-biaxial tension tests of the gasket, the material properties are determined for the use in robust design of PEMFC gasket. The robust design of the PEMFC stack may provide structural reliability.

• Journal of ILASS-Korea
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• v.2 no.4
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• pp.15-21
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• 1997

In a gasoline engine with port injection system, the fuel behavior in the intake port has significant influence on the HC emission and the precise A/F control. That is to say, it is inevitable that the injection direction and behavior of fuel injected in the intake port have an effect on the generation of unburned HC within a cylinder. In this paper, we visualized fuel behavior in the intake port using micro CCD camera synchronized with the stroboscope and investigated the fuel-film characteristics formed at the wall of intake port by processing image captured with VCR in the transparent intake port made of acryl. Using these measuring methods, it was found that fuel behavior and the formation of fuel-film in the intake port could be evaluated qualitatively. And results obtained by these methods show that 2-spray injector minimizes the fuel-film formed in the intake port of a DOHC gasoline engine.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.414-414
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• 2011

핵융합로는 고온의 고밀도 플라즈마에 노출되므로 고 열부하 및 플라즈마 이온에 의한 물성수치를 충분히 고려한 재질로 구축하여야 한다. 특히 핵융합의 연료인 중수소, 삼중수소와 관련하여 플라즈마 대면 부품, 블랑켓, 열 교환기 등의 구축재질에 대한 수소동위원소의 누설거동 데이터 확보는 삼중수소의 취급 및 안전성과 경제성 측면에서 매우 중요하다. 현재 국내의 삼중수소 누설거동과 관련된 실험장치 개발 및 데이터는 관련 연구가 진행되는 선진국에 비해 초보적인 수준이며, 핵융합 기술의 자력개발을 위해서도 수소동위원소 관련 누설거동 데이터의 확보는 매우 중요하다. 본 연구는 삼중수소 누설거동 해석을 위한 예비 실험으로, 수소를 사용하는 누설거동 실험장치를 설계 제작하여 기초실험을 수행하였다. 시편은 스테인레스 스틸(SS-316L)을 사용하였으며, 시편의 두께를 변화시켜가며 수소에 대한 activation energy, permeability, diffusivity, solubility를 구한 후 타 연구그룹의 실험결과와 비교 하였다.

• Journal of Power System Engineering
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• v.5 no.3
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• pp.17-24
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• 2001

In order to investigate a characteristic of the behavior of spray pattern in accordance with running conditions for a DI diesel engine, the PLN Injection system with changeable revolution speed of fuel injection cam was set up, and through this, history curves of injection pressure for a similar real DI diesel engine were able to be displayed. Authors visualized and analyzed the sprays at various revolution speed of fuel injection cam, and found out that fuel distributions of the sprays in the low speed condition were bad, fuel with air was injected from the hole of nozzle at the beginning of injection, and wide spray angle at the early stage of injection became narrower with elapsed time, but wider again at the end of injection.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2390-2395
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• 2008

The water droplet motion in an air flow microchannel with pores through which water emerges is studied numerically by solving the equations governing the conservation of mass and momentum. The gas-liquid interface is tracked by a level set method which is based on a sharp-interface representation for accurately imposing the matching conditions at the interface and is modified to implement the contact angle conditions on the wall and pores. The numerical results show that the droplet growth and detachment pattern depend significantly on the contact angle and inlet air velocity. Also, the dynamic interaction between the droplets growing on multiple pores is investigated. The pore arrangement subject to droplet merging is found to be not effective for water removal.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.32.2-32.2
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• 2011

고체산화물 연료전지의 연결재의 필요한 물성으로는 공기극과 연료극을 차폐시켜줄 수 있는 고밀도와 구성 소재간의 전기적으로 연결될 수 있는 전기전도도 산화극과 환원극에서 화학적 안정성과 타 구성 소재와의 열팽창 계수 등이 중요한 특성으로 필요하게 된다. 이를 위해 $LaCrO_3$계 연결재가 주로 사용되어 왔다. 그러나 LCO계 연결제는 $1,400^{\circ}C$이상의 높은 소결 온도와 이로 인한 Cr의 휘발로 인한 타 구성소재와의 반응 등으로 인해 저온소결의 필요성이 재기되고 있는 소재 이다. 본 연구에서는 LCCCO계 구성 소제에 LaF3, 소결 소제를 첨가하여 저온에서 결정성 및 소결거동, 전기적 특성을 평가하였다.