• Journal of Advanced Marine Engineering and Technology
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• 제36권7호
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• pp.910-918
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• 2012

Carbon monoxide (CO) is a primary air pollutant as an indicator of air quality released from motor vehicle combustion. A comparative study of the distributions of CO concentration with no heat source in two tunnel models open and closed at both end sides is simulated with a commercial CFD code. The tunnel models are used to investigate the CO concentration distributions at three Reynolds numbers, which are computed by the inlet velocities of 0.3, 0.6 and 1.0 m/s. For a better tunnel design, the CFD predictive approaches are available in qualitatively studying the distributions of CO concentration. In the case of the tunnel open at both end sides in sixty seconds, the total CO concentrations are approximately twenty eight percent higher than those in the closed case.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.680-685
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• 2000

Investigation on ignition and flame propagation of pyrolyzing fuel in a cylindrical enclosure is accomplished. The pyrolyzing fuel of cylindrical shape is located in an outer cylinder sustained at high-temperature. Due to gravity, the buoyancy motion is inevitably incurred in the enclosure and this affects the flame initiation and propagation behavior. The radiative heat transfer plays an important role since a high temperature difference is involved in the problem. Numerical studies have been performed over overheat ratio, and vertical fuel eccentricity. The location of flame onset is affected by the vertical eccentricity of inner pyrolyzing fuel as well as thermal conditions applied.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.456-461
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• 2003

A fuel cell is an electrochemical device in which the energy of a chemical reaction is converted directly into electricity. By combining hydrogen fuel with oxygen from air, electricity is formed, without combustion of any form. Water and heat are the only by-products when hydrogen is used as the fuel source. Fuel cell stack consists of multi-layered unit cells. A unit cell consists of MEA and bipolar plates. The end plate of fuel cell stack should give a uniform distributed pressure to multi unit cell layers so as to reduce the contact resistance and to prevent the leakage of reactant gases and the damage of multi layer components. The current end plate is redundantly large and heavy. It makes the power per unit volume reduced. Topology optimization of end plate is conducted for mass reduction and enhancement of bending rigidity. The evaluation of the current design and the recommendation for the future design is remarked.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.2233-2238
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• 2003

It is well known that organized vortex rotations swirl and tumble greatly affect the mixing, the combustion and heat transfer processes in engine cylinder. We have developed 3 dimensional numerical simulation codes whose predictions make good agreement with the experimental data. Large eddy simulation based on Smagorinsky subgrid scale model was adopted to describe the turbulence of in-cylinder flows. The tumble motions generated by different inclination angles between valve-port and cylinder head have been calculated. The results show that the angles between direction of induced flow and cylinder walls which the flow collides with play a great role in the formation and generation of tumble motions. Therefore, it is inferred that seat angle and inclination angle are important factors of engine design. In addition, the numerical results of different engine speed -1000 rpm and 3000 rpm are very similar in the flow structure.

• Journal of Advanced Marine Engineering and Technology
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• 제30권2호
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• pp.253-259
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• 2006

There is few study which automatically diagnoses the fault from ship's monitored data. The bigger control and monitoring system is. the more important fault diagnosis and maintenance is to reduce damage caused by system fault. This paper proposes fault diagnosis system using a correlation analysis algorithm which is able to diagnose and forecast the fault from monitored data and is composed of fault detection knowledge base and fault diagnosis knowledge base. For all kinds of ship's engine room monitored data are classified with combustion subsystem, heat exchange subsystem and electric motor and pump subsystem, To verify capability of fault detection, diagnosis and prediction, FMS(Fault Management System) is developed by C++. Simulation by FMS is carried out with population data set made by the log book data of 2 months duration from a large full container ship of H shipping company.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.928-933
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• 2001

EGR(Exhaust Gas Recirculation) is an effective strategy to control nitrogen oxides emissions from diesel engine. The EGR reduces $NO_x$ through lowering the oxygen concentration in the combustion chamber as well as through heat absorption. However, application of EGR system is difficult because of the penalty in fuel consumption and the increase in particulate matter. The engine used for the experimental was a 3-cylinder 0.8-liter turbo-charged light duty diesel engine with an electronic EGR valve. In this study, experiments were performed at variable vehicle speeds and loads on the chassis dynamometer. To evaluate the exhaust emissions with the EGR system testing was performed using cvs-75 mode test procedure. Results of the cvs-75 mode test achieve sufficiently to meet EURO3 standards.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.511-516
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• 2001

The flow characteristics in a hot mill reheating furnace is numerically simulated in this study. Navier-Stokes equations for conservation of mass, momentum, energy are solved and the standard $k-\varepsilon$ model, mixture fraction/PDF model are used for the turbulent reacting flow in the furnace. Radiation heat transfer is incorporated by the P-1 method with the absorption coefficient evaluated using WSGGM. First, simulation results are obtained for the total furnace region with existing protective dam, and then the calculations are carried out only for the preheating zone in the furnace. In that zone, additional center darn is built in order to control the flow behavior of the inlet air and the combustion gas.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.331-332
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• 2006

연료 분사펌프는 600bar 이상의 고압 연료를 분사밸브를 통하여 디젤기관의 연소실에 연속적으로 공급하는 장치이며, PLUNGER&BARREL 은 분사펌프의 핵심 부품으로 작동하고 고온 고압의 환경에서 $4{\mu}m$ 미만의 초정밀 간극을 유지해야 한다. 이러한 정밀한 가공 상태를 유지하기 위해선 내마모성 및 내열성에 적합한 재료와 열처리가 필수 요소이다. 현재 주로 사용되고 있는 방식은 DIAMOND STONE 에 의한 HORNIG 가공을 주로 사용하기 있다. 하지만, 연삭 가공과는 달리 별도의 치수 보정 장치가 없는 관계로, STONE 마모와 그에 따르는 마모량 공차에 의한 정밀 치수 확보의 어려움으로 인해, 고비용 저효율의 약점을 가지고 있다. 그러므로 기존의 HORNING STONE 방식을 대체한 PIN 방식의 HORNING MACHINE 개발을 목표로 한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.125-128
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• 2004

In this paper, a novel processing technique for fabrication of high-temperature MEMS based on polymer-derived SiCN microstructures is described. PDMS molds are fabricated on SU-8 photoresist using standard UV-photolithographic processes. Liquid precursors are injected into the PDMS mold. And then, the resulting solid polymer structures are crosslinked under isostatic pressure, and pyrolyzed to form a ceramic capable of withstanding over $1500^{\circ}C$. These fabricated SiCN structures would be applied for high-temperature applications, such as heat exchanger and combustion chamber.

• 한국안전학회지
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• 제5권1호
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• pp.41-48
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• 1990

In this study the explosion characteristics of terephtalic acid dust(PTA) was investigated with the Hartmann type apparatus. The minimum ignition energy, minimum explosible concentration, flame propagation velocity, explosion pressure, explosion pressure rise rate and the effect of inert dust(talcum) on explosion characteristics were measured. Flame velocity was 50m/s at 700g/m$^3$ concentration, and the explosion pressure and explosion pressure rise rate were most likely with that of gas explosion. It was found that an inert dust acts as a heat sinker and it disturbs the combustion of flammable dust, as a result, explosion pressure and explosion pressure rise rate were decreased and minimum explosion concentration was increased with increasing the fraction of talcum dust in PTA.