• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2002.04a
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• pp.2-3
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• 2002

일반적으로 연소과정에서 발생한 고온고압의 연소가스로 인하여 액체추진기관의 연소실 및 노즐 벽면 그리고 추진기관 후방부위에 대류열전달(Convective heat transfer)과 복사열전달(Thermal radiative heat transfer)이 발생하는 것으로 알려져 있으며, 액체추진기관에서 발생하는 복사열전달 현상은 재생냉각장치의 열입력량 예측 및 발사체의 추진기관 후방부위에 탑재되는 전자장이 및 구조물의 열적환경(Thermal environmental phenomena)을 분석하는데 매우 중요하다. 이에 본 연구에서는 노즐 후방부위에서 발생하는 복사열전달량(Radiative heat transfer rate)을 측정하고 연소압(Chamber pressure)과 혼합비(Mixture ratio)에 따른 영향을 파악하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.233-234
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• 2006

In this paper, Via hole pore were investigated during PLAS (PessureLess Assisted Constrained Sintering) process of LTCC. Ag and Ag-Pd paste mixture were tested for via paste. Ag paste with 10~25% Ag-Pd paste showed no via hole pore, but further increase of Ag-Pd contents in via paste increased via pore. From shrinkage curve, 10~25% Ag-Pd paste showed expansion behaviors before shrink and this phenomena result in the reduction of via hole pore during PLAS process.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.2
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• pp.260-271
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• 2003

For the Purpose of understanding the mixing phenomena of a GDI(Gasoline Direct Injection) engine, the spray behaviors and fuel distributions were investigated in a single cylinder transparent GDI engine. The experimental engine is a swirl type GDI engine with a SCV(Swirl Control Valve). PLIF(Planar Laser Induced Fluorescence) system with KrF Excimer laser was used for the measurement of the fuel distributions. The effects of SCV opening angles and the injector specifications on the fuel distribution characteristics were investigated. As a result, it was found that the SCV opening angle had a great effect on the fuel distributions in the late stage of compression process by changing the flow fields in the combustion chamber.

• KSTLE International Journal
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• v.10 no.1_2
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• pp.43-47
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• 2009

Influences of carbonaceous ingredient as a solid lubricant in automotive friction materials on friction properties were studied. Three types of carbonaceous ingredients such as natural graphite, artificial graphite, and cokes were mixed using a constrained mixture design. A 1/5 scale brake dynamometer was used to obtain tribological properties. Results showed that cokes substantially increased the friction coefficient, and natural graphite effectively reduced stick-slip phenomena. This significant difference was attributed to the formation of the friction film on the brake pad which was shown to be strongly dependent on the graphite types. The different crystal structures of the carbonaceous solid lubricants played a significant role in the formation of friction film at the interface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.569-572
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• 2001

Selective. highly stable determination of epinephrine(adrenalin) was achieved in cyclic voltammetric measurement carried out at electrochemically treated conductive boron-doped diamond electrode. Boron-doped diamond electrodes were prepared on single crystal Si wafers by microwave plasma chemical vapor deposition and $B_{2}O_{3}$ was dissolved in acetone/methanol(9:1) mixture solution so that the B/C weight ratio ca. $10^{4}ppm$. Epinephrine is a kind of catecholamines, which secreted from adrenal marrow cells. The serious problem to detection of epinephrine is the interference phenomena of electroactive constituent. including AA. In this study. electrochemical treatment of BDD was carried out to discriminate between epinephrine and AA responses. Experimental results showed that the peak potential of AA oxidation shift to the positive direction and the oxidation peak of epinephrine was unchanged. The effect of electrochemical treatment was maintained up to 40hrs.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.99.1-99.1
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• 2011

Reactant mixing has a critical role in ensuring reformate quality and an important design objective is to achieve sufficiently complete mixture of reactants. For that purpose it is required to understand the coupled transport-kinetics phenomena in the mixing region. Three-dimensional computational fluid dynamics model was developed and validated in previous works. The mixing characteristics in various alternatives of a prototype mixing chamber were compared, and then a reduced reaction kinetics was applied to two extreme designs for investigating the impact of gas-phase reactions. Both designs did not reach threshold ethylene mole fraction of 0.001, but surprisingly more ethylene was generated in the design having better mixing characteristics. The presentation will deliver the development process of coupled transport and kinetics model briefly and the detailed information about the mixing characteristics and gas-phase reactions in two mixer designs.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.25-28
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• 2008

Steam reforming reaction is a matured technology to get hydrogen from hydrocarbon fuels compared with other reforming reactions such as partial oxidation(POX), autothermal reforming(ATR). It is so endothermic that it needs heat source to activate the reaction. Due to the reaction characteristics, heat transfer limitation phenomena generally occur in the steam reformer. As one of new ideas, the effect of discontinuous gas feeding is investigated based on heat transfer characteristics. The new operating method is usually favorable at high GHSV region(i.e. over $10,000h^{-1}$). In order to numerically simulate the physical issues, numerical approach is adopted based on heterogeneous reaction model, two-equation model in energy equation, and other constitutive models in porous media.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.2
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• pp.136-145
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• 1995

The aim of this study is to gain a better understanding of the effect of a flow motion on the flame development by means of an optically-accessible constant-volume combustion chamber and the visualization technique of a combustion flame. At first, the characteristics of a flame propagation are investigated in the combustion field of the two kinds of flow conditions such as a quiescent and a flowing condition, and methane-air mixture is used as fuel. Then the same investigation is performed in two flow configurations : bulk flow motion type and turbulence generating type. In this study, the combustion phenomena are analyzed by measuring the combustion pressure, flame propagation speed, mean velocity, turbulent intensity, and mass fraction burned.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.23-27
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• 2005

A fluorescent lamp which uses low pressure mercury-argon gas discharge shows the maximum current and minimum lamp voltage near 1(kHz) source frequency at constant power. For explain these phenomena theoretically, in this paper a atomic level discharge model was made and particle density and electron temperature variation were calculated using numerical method.

• Solar Energy
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• v.8 no.1
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• pp.13-21
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• 1988

Heat transfer phenomena in a high-temperature heat storage unit were investigated using molten salts. Carbonate salt, an equimolar mixture of $Li_2CO_3$ and $K_2CO_3$, which melts at $505^{\circ}C$ with a latent heat of 82 cal/g, was selected as the most promising latent heat storage material based on its low cost and excellent thermophysical properties at moderately high temperatures. It was also found that nitrate salts were good candidates of sensible heat storage materials. For the carbonate salt to be utilized commercially, however, several means of enhancing thermal recovery must be explored by promoting heat conduction through the solid salt formed during the heat discharge period. These would be achieved by the additions of aluminum screens and wool, and stainless fins. Finally, experimental results of moving boundary of phase change were well compared with predictied values obtained from the approximate solution.