• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1658-1663
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• 2004

The feasibility test was performed to check the possibility of 2-phase flow visualization and water distribution at inside the PEMFC using neutron radiography image technique. It was composed using water and pressured air. From the image, several 2-phase flow patterns were discovered and water fraction was estimated by the reference specimen and image analysis.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.181-184
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• 2009

본 연구에서는 고체추진기관 내부유동 모사를 위한 수동에서의 흐름가시화 기법에 대해 소개한다. 이 기법은 고체추진기관 내부에서의 와류 거동들에 대한 적절한 모사로 내부 추진제 그레인 형상 설계시 활용 가능하다. 이를 위해 본 연구에서는 수동을 설계하였으며, 물감, 수소기포발생기 및 입자영상속도계 기법을 활용한 흐름가시화 기법에 대해 소개한다.

• 한국가시화정보학회지
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• 제2권1호
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• pp.46-51
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• 2004

This paper deals with the evaluation of several boundary conditions which are commonly used in the lattice Boltzmann equation method. 2-D channel flow(Poiseuille flow) and lid-driven cavity flow was selected as a test problem of this study, because there exist an analytic solution and previous study which could be used for a benchmarking test. It was found that lattice Boltzmann method still needs more considerations of stability and physical consistency, though it could predict the flow patterns both qualitatively and quantitatively.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2002년도 추계학술대회 논문집
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• pp.117-120
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• 2002

An experimental research has been carried out for flow control of the shock wave/turbulent boundary-layer interaction utilizing aeroelastic mesoflaps. Various shapes and thicknesses of the mesoflap are tested to achieve different deflections of the flap, and ail the results are compared to the solid-wall reference case without flow-control mechanism. Quantitative variation of skin friction has been measured downstream of the interactions using the laser interferometer skin friction meter, and qualitative skin friction distribution has been obtained by observing the interference fringe pattern on the oil-film surface. A strong spanwise variation in the fringe patterns with a narrow region of separation near the centerline is noticed to form behind the shock structure, which phenomenon is presumed partially related to three-dimensional flow structures associated with both the sidewalls and the bottom test surface. The effect of the shape of the cavity is also observed and it is noticed that the shape of the cavity is not negligible.

• 한국분무공학회지
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• 제9권4호
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• pp.77-82
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• 2004

This paper describes the improvement of engine cooling system. To improve engine cooling performance, the authors approached in two ways. One is to increase water pump performance, changing of impeller shape and lightening of material were carried out. The second one is cooling efficiency rise, which were investigated with head gasket coolant flow passage optimization with flow visualization technique. The test results show that water pump performance was increased effectively, reduction of pump drive torque, and increase of pump flow-rate and pressure rise. Gasket hole pattern optimization test results represent an optimized head coolant flow which stands cross flow from exhaust to intake port side and small vortex were removed.

• 한국가시화정보학회지
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• 제16권3호
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• pp.59-64
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• 2018

Numerical simulations were carried out to analyze the flow characteristics of the wind tunnel. Flow field characteristics with velocity uniformity at the test sections are largely affected by inlet conditions of air flow rate and temperature. Axial average velocity of the flow field inside the test area was almost linearly decreased by 0.026% each 1m. The uniformity distributions of axial velocity showed the highest reduction rate of about 24% between nozzle outlets 1 ~ 2m. In addition, average velocity and the uniformity are increased with air temperature in the wind tunnel due to density variation. The results of this paper are expected to be useful for the basic design of wind tunnel and to be used for efficient design.

• 한국가시화정보학회지
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• 제2권2호
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• pp.66-72
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• 2004

The heat transfer and pressure drop characteristics of $CO_{2}$ are substantially different from those for CFC and HCFC refrigerants. In addition, geometric effects on two-phase flow patterns of $CO_{2}$ are also very significant in many respects. Therefore, two-phase flow patterns of $CO_{2}$ in a narrow rectangular channel or a small diameter tube whose gap size or hydraulic diameter is less than 2 mm are very important to understand heat transfer characteristics and to develop an appropriate heat transfer correlation. In the present study, the evaporation process of $CO_{2}$ in a narrow rectangular channel is visualized at various test conditions, and then the effects of operating conditions are analyzed.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 추계학술대회 논문집
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• pp.68-71
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• 2004

The experiments for NACA airfoils are conducted as the preliminary study for the aerodynamic characteristics of the transonic airfoil flow in the shock tube. The test section configurations were designed to use shock tube as simple and less costly experimental facility generating transonic flow at relatively high Reynolds numbers. Experiments at hot gas Mach numbers of 0.80, 0.82 and 0.84, Reynolds numbers of about $1.2\times10^6$ on airfoil chord length and angle of attack of $0^{\circ}\;and\;2^{\circ}$ were carried out by means of shadowgraph visualization method and static pressure measurements. Visualization results were compared with the corresponding results from the conventional transonic wind tunnel tests. The results of study showed that present shock tube facility is useful to study the proper performance characteristics in transonic Mach number range.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2011년도 후기공동학술대회 논문집
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• pp.61-61
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• 2011

Cavitation phenomena during the injection process of the conventional fuel injection pump for a medium-speed diesel engine can cause surface damage with material removal or round-off on the plunger and barrel port and may shorten their expected life time. An experiment of flow visualization was carried out to investigate the main cause of these cavitation damages and find the prevention method. Experimental results of flow visualization show that these damages are mainly affected by fountain-like cavitation and jet-type cavitation generated before and after the end of fuel delivery process and therefore the prevention method was designed to control these cavitation flows. From the visualization and endurance test, it was proved that this method can effectively prevent cavitation damages by controlling cavitation flows.

• 한국추진공학회지
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• 제6권1호
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• pp.55-62
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• 2002

미세수적과 레이저 평면광을 사용하여 새로운 유동의 가시화 방법을 제안하였다. 미세수적은 약 5 내지 $10\mu\textrm{m}$ 크기로 가정용 초음파 가습기를 사용하여 생성시켰다. 조명은 3 W의 알곤 이온 레이저와 원통형 렌즈를 사용하여 레이저 평면광을 특정 와류장 단면에 형성시켰다. 이와 같은 새로운 유동의 가시화 방법을 측정부의 크기가 $0.9 m(W){\times}$0.9 m(H){\times}2.1 m(L)$$인 공군사관학교의 소형 풍동을 통하여 적용하였다. 가시화 결과를 통하여 미세수적을 이용한 새로운 가시화 방법이 풍동실험에 적용하기에 비교적 용이하며, 안전한 방법임을 보였다. 아울러 이 방법은 일반적으로 풍동실험에 적용되고 있는 스모크 가시화의 단점들을 보완함은 물론, 좀 더 높은 유동속도에서도 적용할 수 있었다.