• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.977-980
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• 2003

오늘날 청정에너지 중에서 많은 주목받고 있는 것으로 연료전지를 들 수 있다. 그러나 연료전지의 경우 저전압 대전류의 특성으로 인하여 상용전원에 전원을 공급하기 위해서는 승압 및 상용주파수로 변환해야하는 중간 과정을 거쳐야 한다. 이러한 전력변환장치로 1.5kW를 제작하고 실험으로서 전력 변환장치의 타당성을 검증 하고자 한다.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.195-196
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• 2009

술폰화 폴리아릴렌에테르술폰 공중합체를 기본구조로 한, 6F OH를 알코올 단량체로 사용하여 블록 공중합체를 직접 중합법으로 합성하였다. 이때 각각의 소수성-친수성 소중합체들은 동일한 분자량을 이용하여 합성했으며 그때의 두 소중합체의 몰비는 1:1로 하여 블록 공중합체의 술폰화도를 50%로 고정하였다. N-메틸-2피롤리돈(NMP) 용매 상에서 연료전지용 고분자 전해질 막을 제조하여 이온전도도 및 메탄올 투과도등의 측정을 통하여 최종 블록 공중합체 전해질 막의 기본 특성을 파악했다. 소수성-친수성 소중합체의 분자량을 조절함에 따라 최종 전해질 막의 이온 전도도를 향상시킬 수 있음이 확인되었고, 연료전지 성능 테스트 결과에서도 나피온(Nafion 115)과 비슷한 성능을 보였다.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.288-292
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• 2007

This study focuses on the warm forging of a magnesium alloy impeller used for the fuel cell. The impeller has the very complicated shape with sharply twisted blade and thus is generally produced by mechanical machining or casting process. However, since these technologies give the high manufacturing cost or poor mechanical properties, the forging technology is required to make the high-quality impeller with the lower manufacturing cost. In order for production of the impeller by warm forging technology, the parametric studies using finite element analyses were carried out to find the optimal perform shape of impeller. Based on the FE simulation results, dies for impeller forging were designed and the resultant forged impeller was shown.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.8-14
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• 2009

Effect of heterogeneity of combustion chamber has been thought as one of the way to avoid dramatically generating heat in HCCI Combustion. The purpose of this research is to investigate the effect of heterogeneity, especially thermal stratification and fuel strength stratification on HCCI Combustion fueled with DME and n-Butane. Thermal stratification is formed in Combustion Chamber of Rapid Compression Machine with 3 Kinds of pre-mixture has different properties. The stratified charge mixture is adiabatic compressed and on that process, in cylinder gas pressure and two-dimensional chemiluminescence images are measured and analyzed.

• Journal of Power System Engineering
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• v.14 no.6
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• pp.5-12
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• 2010

In this study, an analysis of evaporative diesel spray and an usefulness of a general-purpose program, ANSYS CFX release 11.0, are investigated through the comparison and investigation of the experimental results carried out under an evaporative field, in which there is phase transition, by an exciplex fluorescence method and the results analyzed by the CFX program. The diesel fuel called n-Tridecane, $C_{13}H_{28}$, is injected from a single-hole nozzle (l/d=1.0mm/0.2mm) into a constant volume chamber under a high temperature and pressure. In the same condition as the experimental condition, the analysis was carried out. Both results of the spray tip penetration were almost coincident at each time. The results have validated the usefulness of this analysis. As a result, if the ambient pressure is high, the spray tip penetration will be shortened and move toward the nozzle exit.

• Nuclear Engineering and Technology
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• v.47 no.1
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• pp.94-101
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• 2015

This paper presents findings on the second-order sliding-mode controller for a nuclear research reactor. Sliding-mode controllers for nuclear reactors have been used for some time, but higher-order sliding-mode controllers have the added advantage of reduced chattering. The nonlinear model of Pakistan Research Reactor-1 has been used for higherorder sliding-mode controller design and performance evaluation. The reactor core is simulated based on point kinetics equations and one delayed neutron groups. The model assumes feedback from lumped fuel and coolant temperatures. The effect of xenon concentration is also considered. The employed method is easy to implement in practical applications, and the second-order sliding-mode control exhibits the desired dynamic properties during the entire output-tracking process. Simulation results are presented to demonstrate the effectiveness of the proposed controller in terms of performance, robustness, and stability.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.543-551
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• 1999

Diesel engine is a major source of the air pollution. In general the concentrations of these pollu-tants in diesel engine exhaust differ from values calculated assuming chemical equibrium. Thus the detailed chemical mechanisms by which these pollutions form and the kinetic of these process-es are important in determining emission levels. In this study the computer program has been developed to calculate the required thermodynam-ic properties of combustion products(10 spacies) for both equilibrium and non-equilibrium in cylin-der for diesel engines. Nitric oxide emissions are calculated by using the extended Zeldovich Kinet-ic mechanism with a steady state assumption for the N concentration and equilibrium values used for H, O, $O_2$ and OH concentrations. By the results it is confirmed that developed simulations program with the NO prediction model is validated against residual mass fraction combustion index of Wiebe's functions pre-mixed com-bustion ration fuel injection timing.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.1
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• pp.95-106
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• 1992

For commercial application of the MCFC, the life time of the MCFC should exceed 40,000 hours, But the life time of the state-of-the-art MCFC was limited to 15,000 hours. The main reasons of the life time limit can be classified as the deficiency of the electrolyte and cathode dissolution. It has been found that the electrolyte deficiency is caused by the continuous evaporation of the electrolyte. However a recent reaserch shows that an electrolyte pumping phenomenon, which implies, the migration of the electrolyte through the gasket material of the external gas manifold, is also the reason of the electrolyte deficiency. Due to the electrolyte pumping phenomenon, positive end cell of the stack suffers the electrolyte deficiency and negative end cell of stack is flooded with electrolyte. Therefore, the cell performance is degraded. The author invented a new manifoldcasing, which prevents the contact between the wet seal and the gasket of the manifold, and gives a complete elimination of an electrolyte pumping effect.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.114-115
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• 2018

To develop an effective shielding material for spent fuel that emits fast neutrons is necessary. In this study, thermal neutron and fast neutron shielding performance of polyethylene coated boron carbide-incorporated cement paste was quantitatively analyzed by Monte Carlo N-Particle transport code (MCNP) simulations. As the results of the simulations, fast neutrons were effectively shielded through large quantity of hydrogen and boron elements in polyethylene and boron carbide.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.139-144
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• 2012

In the automobile industry, the various efforts to lower their industrial cost and enhance fuel efficiency have been made through process improvement or weight saving of automobile parts. Gear is one of significant parts of transmission, which is made by cast iron or alloy steel. It is expensive due to complex processing, inferior materials and large machining allowance. In this study, alternative gear cars oil which is based on fluid applications materials is produced by reducing surface induction hardening and carburizing hardened in production. And then, wear characteristic and mechanical properties such as hardness of the sintered alloy which is used as a substitute for small machining allowance is investigated.