• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.276-281
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• 2000

A simulation program using the mass transfer correlation was constructed to analyze 1-D simplified condensing flow across the tube bank. Higher efficiency was anticipated by reducing the flue gas temperature down below the dew point where the water vapor in the flue gas is condensed at the surface of the heat exchanger; that is, the heat transfer by the latent heat is added to that by the sensible heat. Thus, there can be an optimum operating condition to maximize the heat recovery from the flue gas. The temperature rises of the flue gas and the cooling water between the inlet and the outlet of the tube bank were compared with the experimental data reported previously. The predicted results agree well with the experimental data. Using this simulation program, the parametric studies have been conducted fur various operating conditions, such as the velocities and temperatures of the vapor/gas mixture and the cooling water, the number of the rows, and the conductivity of the wall material.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.673-679
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• 2000

LNG Carriers are currently known as sole commercial means of shipping natural gas on the sea. They are designed to proven dangerous explosion for shipping a lot of gas over long distance. In this study. In this study, a scaled model chamber was made to investigate ventilation characteristics of the hood room in LNG carrier. Experimental study was performed in model using visualization equipments with laser apparatus and image intensifier CCD camera gated by an AOM controller Twelve different kinds of measuring area were selected as experimental condition. Instant simultaneous velocity vectors at whole field were measured by using 2-D PIV system which software adopts two-frame grey-level cross correlation algorithm. To look into stagnation area of hood room for LNG carrier, a three-dimensional numerical simulation with standard ${\kappa}-{\varepsilon}$ model was carried out by using PHOENICS for three kinds of Reynolds number, $6.5{\times}10^3$, $9.7{\times}10^3\;and\;1.29{\times}10^4$, based on the cavity inlet velocity and cavity height. The flow pattern showed the large scale counter-clockwise forced-vortex rotated at center area, small eddies at each corner and stagnation area located at left-back upper side of model.

• 대한의용생체공학회:의공학회지
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• 제36권4호
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• pp.135-142
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• 2015

Outflow cannulation site of left ventricular assist device(LVAD) chosen by considering anatomical structure of thoracic cavity and vascular system. Though outflow cannulation site influences blood perfusion at each branch, there is no standard rule or quantitative data. In this study, we computed the amount of blood perfusion at each arterial branch numerically according to outflow cannulation sites(ascending aorta, aortic arch, descending aorta). We generated computational meshes to the three-dimensionally reconstructed arterial system. Clinically measured arterial pressure were used for inlet boundary condition, porous media were applied to mimic blood flow resistance. Blood perfusion through left common carotid artery was 2.5 times higher than other cases, and that through right common carotid artery was 1.1 times higher than other branches. Although this is simulation study, will be useful reference data for the clinical study of LVAD which considers blood perfusion efficiency.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.39-48
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• 2006

An engine cooling system affects overall performances of an engine which has been recently requested higher power in more confined engine room. The design of efficient cooling system demands a great effort to effectively correlate with each components, such as water jacket, radiator, coolant pump, cooling fan, etc. Thus, the aim of this study is to provide the design tool of the cooling system in the early design stage by enabling for the designer to accurately predict the engine cooling performances. This user-friendly design tool has various ways to assemble each components and control the running condition with related database. The present design tool was simulated and compared with experimental data. As a result, the inlet and outlet temperature of the radiator agree very well with experiments. It was concluded that the present design tool could be effectively used for the design of the engine cooling system.

• 한국자동차공학회논문집
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• 제9권6호
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• pp.94-102
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• 2001

The thermodynamic second law analysis, which means available energy or exergy analysis, for the indicated performance of Otto cycle engine has been carried out. Each operating process of the engine is simplified and modeled into the thermodynamic cycle. The calculation of the lost work and exergy through each process has been done with the thermodynamic relations and experimental data. The experimental data were measured from the test of single cylinder Otto cycle engine which operated at 2500 rpm, WOT(Wide Open Throttle) and MBT(Minimum advanced spark timing for Best Torque) condition with different fuels: gasoline, methanol and mixture of butane-methanol called M90. Experimental data such as cylinder pressure, air and fuel flow rate, exhaust gas temperature, inlet gas temperature and etc. were used for the analysis. The proposed model and procedure of the analysis are verified through the comparison of the work done in the study with experimental results. The calculated results show that the greatest lost work is generated during combustion process. And the lost work during expansion, exhaust, compression and induction process follows in order.

• 한국추진공학회지
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• 제10권3호
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• pp.90-98
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• 2006

재생냉각 시스템의 냉각제로 사용하는 탄화수소계열 연료인 Jet A-1의 냉각특성과 강제대류 열전달 특성을 파악하기 위해 가열된 직선 튜브를 제작하였다. 냉각제의 입, 출구온도와 튜브의 외벽 온도를 측정하여 강제대류 열전달 특성을 고찰하였다. 결과를 통하여 Jet A-1을 사용한 경우에는 일정 유동조건에 대하여 burnout이 발생하는 최초의 벽 온도를 결정함으로써 냉각제가 수용할 수 있는 최대 열유속을 확인하였다. 냉각제의 유속과 입구온도가 대류열전달 특성에 직접적인 영향을 주는 인자임을 확인하였다.

• 청정기술
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• 제10권2호
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• pp.89-100
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• 2004

도장부스 수조 내에 부유되는 도장 슬러지의 효율적인 분리를 위한 수조 형상 및 skimmer 설치에 대한 설계를 최적화하였다. VOF 모델을 사용하여 수조 내 도장 슬러지-물-공기 혼합물의 유동형태에 대한 해석을 수행하였고, 해석된 결과를 바탕으로, 수조 내 물로부터 효과적인 슬러지 분리를 위한 도장 부스 수조 내 흡입관, 격판 및 슬러지 유입구의 설치에 대한 최적 설계 기준을 제시하였다. 더 나아가, skimmer 가 수조 내 물에 잠기는 설치조건에 대한 최적화를 통하여 슬러지 흡입 시 공기 혼입 및 압력손실을 최소화 하였다.

• 대한기계학회논문집
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• 제14권5호
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• pp.1272-1281
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• 1990

본 연구에서는 압력형 경계조건을 취급할 수 있도록, 속도 경계조건만을 취급 하는 전형적인 프로그램을 수정하여 실제 상황에 가까운 실내 공간 내부의 유동장을 예측하였다. 이때 난류 흐름방식의 강제 대류를 해석하기 위한 지배방정식으로서는 저레이놀즈수 K-.epsilon. 난류 모델을 도입하였다. 실내로 유입되는 공기의 영향을 받는 유동장이 예측된 후에는 실내에 존재하는 오염원의 갯수를 변화시키면서 실내 공간 에서의 오염 물질 분포를 수치적으로 계산하였다. 본 연구에서의 실내공간은 2차원 이라 가정하였으며 유동은 정상유동이라 간주하였다. 또한 실내 공간을 채우는 공기 량에 비하여 오염 물질의 양은 그 질량비가 0.1% 이하로서 상대적으로 아주적으므로, 오염된 공기의 밀도는 오염되지 않은 공기의 밀도와 동일하다고 가정한다.

• 설비공학논문집
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• 제7권1호
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• pp.161-170
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• 1995

This study is concerned with the numerical analysis of performance on fin-tube heat exchanger under frosting condition. In this work, tube-by-tube method using LMED is employed. The present results are compared with O'Neal's experimental and numerical results. A standard evaporator model with 2rows-2columns is selected to investigate the effects of the various parameters such as fin pitch, air flow velocity, and humidity. The results show that frost thickness and the amount of frost per unit area decrease as fin-pitch becomes narrower. In the meantime, frost thickness and accumulation rate increase with higher inlet air humidity. It is shown that heat transfer rate increases during 30minutes and then it decreases. Heat transfer rate and the amount of frost increase with air velocity, however frost thickness does not increase over a certain velocity.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2454-2459
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• 2008

The objective of this paper is to find out the most effective injection angle for the purpose of deicing through SC/Tetra, a commonly used CFD software. Nowadays, vehicles are developed giving priority to an improved interior which emphasizes a pleasant environment and thermal comfort without decreasing the basic performance. Clear visibility is one of the most important phenomenon. The primary factors which affect the efficiency of deicing are 3D geometry of Defrost Nozzle, the inlet velocity and temperature of the flow and the injection angle. However in this paper, all these parameters are optimized by changing the injection angle. A wide range of injection angle from 5 degree to 50 degree have been considered for analysis. A very good defrosting performance has been achieved with 45 degree injection angle which can satisfy the condition of NHTSA.