• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1999년도 춘계 학술발표회 논문집
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• pp.95-100
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• 1999

One of the unsolved problems of the natural gas dual fuel engine is that there is too much exhaust of Total Hydrogen Carbon(THC) at a low equivalent mixture ratio. To fix it, a natural gas mixed with hydrohen was applied to engine test. The results showed that the higher the mixture ratio of hydrogen to natural gas, the higher the combustion efficiency. And when the amount of the intake air is reached to 90% of WOT, the combustion efficiency was promoted. But, like a case making the injection timing earlier, the equivalent mixture ratio for the nocking limit decreases and the produce of NOx increases.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.131-139
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• 2001

Highly accurate control of the air-fuel ratio is important to reduce exhaust gas emissions of the gaseous-fuel engines. In order to achieve this purpose, inlet air mass flow must be measured exactly, and precise engine models are necessary to design engine control systems. In this paper, the effects of water vapor and gaseous fuel that change the air mass flow are studied. The effective air mass ratio is defined as the air mass flow divided by the mixture mass flow, and also it is applied to the estimation of the inlet air mass flow. The presence of the gaseous fuel and the water vapor in the mixture reduces the air partial pressure and the effective air mass ratio of the gaseous-fuel engines. The Experimental results for an LPG engine show that the estimation of the inlet ai mass flow based upon the effective air mass ratio is more accurate than that of the normal air mass flow.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.49-54
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• 2003

The purpose of this work is to investigate the effect of premixed fuel on the reduction of exhaust emissions in premixed charge compression ignition engine. The premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber. The pre-mixture is ignited by a small amount of diesel fuel directly injected into the cylinder. In the case of gasoline as a premixed fuel of the engine, $NO_x$ and smoke concentration of exhaust emissions were reduced compared with the conventional diesel engine. But in the event of diesel fuel for premixed fuel, the rate of smoke reduction was small compared with the case of gasoline as a premixed fuel. HC and CO emissions were increased at high premixed ratio in the case of two premixed fuels. The combustion characteristics of the engine such as the combustion pressure, the rate of heat release, and other characteristics are compared.

• Bulletin of the Korean Chemical Society
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• 제31권6호
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• pp.1577-1582
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• 2010

A 20 wt % Pt/C is fabricated and characterized for use as the cathode catalyst in a polymer electrolyte membrane fuel cell (PEMFC). By using the polyol method, the fabrication process is optimized by modifying the carbon addition sequence and precursor mixing conditions. The crystallographic structure, particle size, dispersion, and activity toward oxygen reduction of the as-prepared catalysts are compared with those of commercial Pt/C catalysts. The most effective catalyst is obtained by ultrasonic treatment of ethylene glycol-carbon mixture and immediate mixing of this mixture with a Pt precursor at the beginning of the synthesis. The catalyst exhibits very uniform particle size distribution without agglomeration. The mass activities of the as-prepared catalyst are 13.4 mA/$mg_{Pt}$ and 51.0 mA/$mg_{Pt}$ at 0.9 V and 0.85 V, respectively, which are about 1.7 times higher than those of commercial catalysts.

• 한국자동차공학회논문집
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• 제13권2호
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• pp.178-185
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• 2005

The synergistic effect of ethylene/propane mixture on soot formation is studied experimentally using a concentric co-flow diffusion burner, which provides the stratified fuel mixture. The soot volume fraction, soot particle diameter, number density and PAH concentrations are measured with various fuel supply configurations and compared to the homogeneously mixed case. When propane is supplied through the inner nozzle, an increase of soot formation is observed. However, when propane is supplied through the outer nozzle, a decrease is observed. The reaction path of PAH's formed from the pyrolysis process of propane is likely to be responsible to the observed differences. When propane is supplied through the outer nozzle, PAH's are formed in the relatively near oxidation region and exposed to the oxidization environment; on the other hand, when propane is supplied through the inner nozzle, PAH's are not likely to be oxidized and thus get involved in soot formation process. The synergistic effect in ethylene/propane diffusion flames is found to be affected not only by the com position of the mixture but also by the way of mixing.

• 대한기계학회논문집
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• 제16권9호
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• pp.1736-1743
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• 1992

본 연구에서는 기화기부착 4행정 4기통 전기점화기관을 사용하여 흡기관내 액 막흐름에 의한 연료의 불균일화가 기관의 연소특성과 배기특성에 미치는 영향을 규명 하는데 궁극적인 목적을 두고 우선, 연소특성을 해석하기 위하여 비교적 고가인 연소 해석 시스템을 개발하는데 1차적인 목적으로 하였으며, 시험제작한 연소해석 시스템으 로 액막흐름의 가시화 및 배기가스 농도측정과 지압선도 해석을 행하여 구조적으로 대 칭인 1번과 4번 실린더의 연소특성과 배기특성을 비교 검토하였다.

• International Journal of Aerospace System Engineering
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• 제5권2호
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• pp.16-22
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• 2018

An analysis has been made on the performance variation due to pressure drop change at propellant supply pipes of liquid rocket engine. The objective is to compare the effectiveness of control variables to tune the liquid rocket engine performance. The mode analysis program has been used to estimate the engine performance for different modes which is realized by controlling the flow rate of propellant. The oxidizer of combustion chamber, the fuel of combustion chamber, the oxidizer of gas generator and the fuel of gas generator are the independent variables to control engine thrust, engine mixture ratio and temperature of gas generator product gas. The analysis program is validated by comparing with the powerpack test results. The error range of compared variables is order of 4%. After comparison of tuning effectiveness it is turned out that the pressure drop at oxidizer pipe of gas generator and pressure drop at combustion chamber fuel pipe and the pressure drop at the fuel pipe of gas generator can effectively tune the thrust of engine, mixture ratio of engine and temperature of product gas from gas generator respectively.

• Journal of Electrochemical Science and Technology
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• 제14권3호
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• pp.283-292
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• 2023

Currently, spray coating has attracted interest in the mass production of anode catalyst layers for proton exchange membrane water electrolysis (PEMWE). The solvent in the spray ink is a critical factor for the catalyst dispersion in ink, the microstructure of the catalyst layer, and the PEMWE performance. Herein, various pure organic solvents were examined as a substitute for conventional isopropanol-deionized water (IPA-DIW) mixture for ink solvent. Among the polar solvents that exhibited better IrO₂ dispersion over nonpolar solvents, 2-butanol (2-BuOH) was selected as a suitable candidate. The PEMWE single cells were fabricated using 2-BuOH at various ionomer contents, spray nozzle types, and drying temperatures, and their performance was compared to the cells fabricated using a conventional IPA-DIW mixture. The PEMWE single cells with 2-BuOH solvent showed good performances comparable to the conventional IPA-DIW mixture case and highly durable performances under accelerated degradation tests.

• 한국자동차공학회논문집
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• 제22권1호
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• pp.183-192
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• 2014

In this work, the mixture formation and atomization characteristics of biodiesel fuel were reviewed under various test conditions for the optimization of compression-ignition engine fueled with biodiesel. To achieve these, the effect of nozzle caviting flow, group-hole nozzle geometry and injection strategies on the injection rate, spray evolution and atomization characteristics of biodiesel were studied by using spray characteristics measuring system. At the same time, the fuel heating system was installed to obtain the effect of fuel temperature on the biodiesel fuel atomization. It was revealed that cavitation in the nozzle orifice promoted the atomization performance of biodiesel. The group-hole nozzle geometry and split injection strategies couldn't improve it, however, the different orifice angles which were diverged and converged angle of a group-hole nozzle enhanced the biodiesel atomization. It was also observed that the increase of fuel temperature induced the quick evaporation of biodiesel fuel droplet.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.297-300
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• 2006

The knowledge of fuel load and composition is important for planning and managing the fire hazard and risk. However, fuel mapping is extremely difficult because fuel properties vary at spatial scales, change depending on the seasonal situations and are affected by the surrounding environment. Remote sensing has potential of reduction the uncertainty in mapping fuels and offers the best approach for improving our abilities. This paper compared the results of object-oriented classification to a pixel-based classification for fuel type map derived from Hyperion hyperspectral data that could be enable to provide this information and allow a differentiation of material due to their typical spectra. Our methodological approach for fuel type map is characterized by the result of the spectral mixture analysis (SMA) that can used to model the spectral variability in multi- or hyperspectral images and to relate the results to the physical abundance of surface constitutes represented by the spectral endmembers. Object-oriented approach was based on segment based endmember selection, while pixel-based method used standard SMA. To validate and compare, we used true-color high resolution orthoimagery