• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.2
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• pp.86-92
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• 2014

Combustion Chamber Test Facility (CCTF) to be constructed in Naro Space Center for re-burning the fuel-rich gas of gas generator have afterburner system. The afterburner system is supplied the Oxygon ($O_2$) gas and Methane ($CH_4$) gas to reduced the harmful exhaust gas. The detailed design for the planned CCTF afterburner system is simulated and analysed by AMESim program through the all of gas supply system components. Afterburner system is performed to verify the pipe size, orifice diameter, and gas supply conditions according to the total gas consumption from analysis of gas supply system.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.106-114
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• 1999

Today, one of the most important objective in automobile development is to reduce the weight of automobile . The eventual depletion of petroleum and environmental regulations brought considerable emphasis to this area on increasing fuel efficiency. Conventional intake air-fuel system is very heavy because it is composed of numerous parts. The bulky size caused increase in the amount of metal being used to build automobile chassis and this became a serious weight problem. The size also caused difficulties in optimization of fuel supply system which in turn decreased engine efficiency. Currently , there are efforts to integrate several intake system modules into one. The purpose of this paper is to evaluate the directions of such development.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.3
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• pp.175-186
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• 2004

In this paper, we developed the dynamic model of a fuel cell system suitable for controller design and system operation. The transient phenomena captured in the model include the flow characteristics and inertia dynamics of the compressor, the intake manifold filling dynamics, oxygen partial pressures and membrane humidity on the fuel cell voltage. In the simulations, we paid attention to the transient behavior of stack voltage and compressor pressure, stoichiometric ratio. Simulation results are presented to demonstrate the model capability. For load current following, stack voltage dynamic characteristics are plotted to understand the Electro-chemistry involved with the fuel cell system. Compressor pressure and stoichiometric ratio are strongly coupled, and independent parameters may interfere with each other, dynamic response, undershoot and overshoot.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.396-401
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• 2003

In the present study, preliminary investigation were carried out by analysis of energy system(heat and electricity) based on phosphoric acid fuel-cell of 50 kW for eco-apartment houses. Analysis model were consisted of fuel cell energy system, secondary energy unit and residential building of 5 stories with 20 and 40 households. And the investigation results reviewed under load pattern of heat and electric power of the apartment houses. The results showed mismatch between the needed heat load pattern and output of fuel cell energy system. The mismatch rate were assessed about 10-180% of heat load for apartment houses with season. We found that secondary energy unit are needed in order to supply insufficient heat.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.1
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• pp.117-123
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• 2003

In a bi-fuel engine using gasoline and LPG fuel, with the current ignition timing for gasoline being used, the effective performance could not be taken in LPG fuel supply mode. The ignition timing in LPG fuel mode must be advanced much more than that of gasoline mode for the compensation of its lower flame speed, due to engine torque drop. This study aims to develop the control system for ignition spark timing conversion which is composed of hardwares and control algorithm for gasoline/LPG engine. We propose the control system which can advance the ignition spark timing in LPG fuel mode more than used in gasoline fuel mode. The advance of ignition timing is achieved by change of the ignition dwell time of coil igniter. The engine torque and F/E(Fuel-Economy) in LPG fuel mode are measured to evaluate the difference of engine performance between before and alter changing ignition spark timings. The engine torque and F/E are increased respectively, which proves the developed control system is effective so much for gasoline and LPG bi-fuel engine.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.6
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• pp.447-460
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• 2012

In this study, the shutdown system of the fuel gas supply system is designed based on the Safety Integrity Level of IEC 61508 and IEC 61511. First of all, the individual risk($10^{-4}$/year) and the risk matrix which are the risk acceptance criteria are set up for the qualitative risk assessment such as the HAZOP study. The natural gas leakage at the gas supply pipe is identified as the highest risk among the hazards identified through the HAZOP study and as a safety instrumented function the shutdown function for leakage was defined. SIL 2 and PFD($2.5{\cdot}10^{-3}$) for the shutdown function are determined by the layer of protection analysis(LOPA). The shutdown system(SIS) carrying out the shutdown function(SIF) is verified and designed according to qualitative and quantitative requirements of IEC 61508 and IEC 61511. As a result of SIL verification and SIS conceptual design, the shutdown system is composed of two gas detectors voted 1oo2, one programmable logic solver, and two shutdown valve voted 1oo2.

• Proceedings of the KAIS Fall Conference
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• 2002.11a
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• pp.141-144
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• 2002

Recently, the operation of power distribution systems has become more difficult because the peak demand load is increasing continuously and the daily load factor is getting worse and worse. Also, the consideration of deregulation and global environment in electric power industry is required. In order to overcome these problems, a study on the planning and operation in distribution systems of dispersed generating sources such as fuel cell systems, photovoltaic systems and wind power systems has been performed energetically. This study presents a method for determining an optimal operation strategy of dispersed co-generating sources, especially fuel cell systems, in the case of both only electric power supply and thermal supply as well as electric power supply. In other words, the optimal operation of these sources can be determined easily by the principle of equal incremental fuel cost and the thermal merits is evaluated quantitatively through Kuhn-Tucker's optimal conditions. In order to select the optimal locations of those sources, an priority method using the comparison of total cost at the peak load time interval is also presented. The validity of the proposed algorithms is demonstrated using a model system.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.97-104
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• 2014

In this study, preliminary thermal sizing was performed with the aim of developing a fuel supply and cooling system design to solve the heating problems in high-speed vehicles. First, an analysis model was used to satisfy an optional mission profile. The heat loads were computed under boundary conditions. The results were verified using the precedent design case. Then, fuel consumption rates were estimated for the analysis trajectory. Accordingly, the cooling capacity in the system was calculated using the heat sink capacity of the endothermic fuel. Lastly, the fulfillment of the design requirements was confirmed in comparison to the cooling needs.

• Journal of Energy Engineering
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• v.14 no.3 s.43
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• pp.173-179
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• 2005

Fuel injection system has more benefits in power, fuel consumption and emission than carburetor system even in high speed small engine. Up to date fuel injection system is used in motor car but is not used in motorcycles in Korea. EFI (Electronic fuel injection) system which has ECU can control precise fuel supply to variable RPM in engine. The purpose of this study is the investigation of effects of fuel injection system to improve the engine performance and efficiency in variable revolution of high speed small engine which is 4 Valves SOHC single cylinder engine used in motorcycle.

• Journal of ILASS-Korea
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• v.2 no.1
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• pp.29-35
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• 1997

Many technologies have been developed to improve diesel emissions or performance, however NOx/PM trade-off occurs because normal methods that reduce NOx emissions tend to increase PM emissions. On the other hand many measures used to control PM emissions tend to increase NOx emissions. Thus, simultaneously controlling both NOx and PM emissions has become a significant challenge for diesel engine manufacturers. As one of the measures, the technology using emulsified fuel has recently become important under the stringent emission regulations of diesel engines. This paper investigates injection characteristics of emulsified fuel and its effect on a combustion performance in a diesel engine. In order to supply emulsified fuel into injection system a mixing unit produced by Harrier is used, then the fuel mixed with water is supplied into injector directly. The spray injected is investigated with a shadowgraph photo system and injection analyzing apparatus, then applied into a diesel engine. Those results showed that the emulsified fuel has an effect on reducing both NOx and PM.