• 대한기계학회논문집B
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• 제23권2호
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• pp.185-197
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• 1999

Heat transfer and solidification of liquid silicon in von-$K{\acute{a}}rm{\acute{a}}n$ swirling flow is investigated. The moving boundary is fixed for all times by a coordinate transformation, and finite difference method Is used to obtain the instantaneous location of the solid-liquid Interface and the heat transfer from the surfaces of solid and liquid. For small Stefan number or low wall temperature, the transient heat transfer from the surface of solid(QS(t)) is much larger than that from the liquid side of solid-liquid interface(QL(t)) and QL(t) reaches its quasi-steady-state value much faster than QS(t).

• 한국분무공학회지
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• 제11권2호
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• pp.113-120
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• 2006

The effect of internal liquid flow on spray plume characteristics was performed experimentally in subsonic cross flows. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of the research are to investigate the effect of internal liquid flow on the spray plume characteristics and compare the trajectory of spray plume with previous works. The results suggest that the trajectory and width of spray plume can be correlated as a function of liquid/air momentum flux ratio(q), injector diameter and normalized distance from the injector exit(x/d). It's also found that the injector internal turbulence influences the spray plume characteristics significantly.

• 공업화학
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• 제16권1호
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• pp.34-38
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• 2005

직경이 0.102 m이고 높이가 2.5 m인 유동층 액-액 추출기에서 액적의 크기와 분포 그리고 상승속도의 특성에 대하여 연구하였다. 분산상(0~0.04 m/s)과 연속상(0.02~0.14 m/s)의 유속변화, 그리고 유동고체 입자의 크기변화(1.0, 2.1, 3.1, 6.0 nm)에 따른 액적의 특성을 검토하였다. 액적의 흐름 거동은 추출기 내부에서 액적의 흐름 거동은 분산상과 연속상의 증가와 액적의 크기에 따라 상당히 영향을 받았다. 액적의 크기는 분산상의 속도가 증가함에 따라 증가하였지만, 유동입자의 크기가 증가함에 따라 따라서는 감소하는 경향을 나타내었다. 그러나 연속상의 유속이 증가함에 따른 액적의 크기는 국부적인 최대값을 나타낸 후 감소하는 경향을 나타내었다. 액적의 크기와 상승속도는 실험변수들과 잘 상관됨을 알 수 있었다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.59-60
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• 2006

Some useful flow regime data are obtained from the experiments using the flight producing hyper-gravity(2g) conditions and on ground(1g) with the identical flow conditions. The flow regime data obtained at 1g and 2g conditions are compared with new dimensionless flow regime map using Fr, Bo and We number related with gravity, surface tension and inertia force.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.335-338
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• 2009

액체로켓에 산화제를 충전하는 과정은 크게 산화제 탱크의 냉각, 고유량 충전, 소유량 충전, 온도 보정을 위한 추가 충전으로 나눌 수 있다. 나로호(KSLV-I) 1단의 산화제는 액체산소를 사용하며, 각 충전모드에 해당하는 유량 및 온도 요구조건이 제시되어 있다. 이러한 유량 및 온도 요구조건을 만족하기 위해서 산화제 공급시스템에는 유량조절용 밸브와 열교환기가 설치되어 있다. 본 연구에서는 발사체 산화제 충전과정에서 정밀한 유량 공급을 위하여 상용 1차원 열-유동 해석 프로그램인 Flowmaster를 이용하여 1차원 유동 시스템 해석을 수행하였다. 아울러 제한된 인증 시험을 통하여 각 모드에서의 유량 조건을 만족시키기 위한 유량제어밸브들의 유량 보정 민감도를 해석적으로 구하였다.

• 대한기계학회논문집B
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• 제28권10호
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• pp.1271-1278
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• 2004

In order to measure non-intrusively velocity profile in liquid metal flow, a modified electromagnetic flowmeter was designed, which was based on electromagnetic tomography technique. Under the assumption that flow is fully-developed, axisymmetric and rectilinear, the velocity profile was reconstructed after the flowmeter equation, the first kind of Fredholm integration equation, was linearized. In reconstruction process Tikhonov regularization method with regularization parameter was used. The reconstructed velocity profile had the nearly same as turbulent flow profile which was approximately represented as log law. In addition, flowmeter output fur a fixed magnet rotation angle was linearly proportional to flow rate. When magnet rotation angle was 54$^{\circ}$, axisymmetric weight function was nearly uniform so that the flowmeter gives a constant signal for any fully-developed, axisymmetric and rectilinear profile with a constant flow rate.

• 한국해양공학회지
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• 제28권4호
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• pp.280-287
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• 2014

In this paper, the numerical simulation of the gas-liquid flow in a cylinder cyclone separator is performed to investigate the flow characteristics using a commercial software, FLUENT, which solves the Reynolds-averaged Navier-Stokes(RaNS) equations. First, a single-phase flow with water in a gas-liquid cylinder cyclone(GLCC) separator is simulated and compared with the experiments(Farchi, 1990) and numerical simulations(Erdal, 1997). Then, the characteristics of the multi-phase flow for water-air, mud-only, and mud-air cases are discussed in the view point of the feasibilities for a mud handling system.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2002년도 춘계 학술대회논문집
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• pp.146-151
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• 2002

Characteristics of flow rate control has been studied for a cavitating venturi adopted in a liquid rocket propellant feed system. Numerical simulation has been peformed to give about $10\%$ discrepancy of mass flow rate to the experimental data for cavitating flow regime. Mass flow rate is confirmed to be saturated for pressure difference higher than $3\times10^5$pa when the upstream pressure is fixed to $22.8\times10^5$pa and the downstream pressure is varied. The evaporation amount depends substantially to non-condensable gas concentration. However the mass flow rate characteristic is relatively insensitive to the mass fraction of non-condensable gas. So it is reduced by only $2\%$ when the non- condensable gas concentration is increased from 1.5PPM to 150PPM. From the previous comparison the expansions of the non-condensable gas and the evaporation of liquid are verified to have same effect to pressure recovery.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1749-1754
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• 2004

In order to measure non-intrusively velocity profile in liquid metal flow, a modified electromagnetic flowmeter was designed, which was based on electromagnetic tomography technique. Under the assumption that flow is fully-developed, axisymmetric and rectilinear, the velocity profile was reconstructed after the flowmeter equation, the first kind of Fredholm integration equation, was linearized. In reconstruction process Tikhonov regularization method with regularization parameter was used. The reconstructed velocity profile had the nearly same as turbulent flow profile which was approximately represented as log law. In addition, flowmeter output for a fixed magnet rotation angle was linearly proportional to flow rate. When magnet rotation angle was $54^{\circ}$, axisymmetric weight function was nearly uniform so that the flowmeter gives a constant signal for any fully-developed, axisymmetric and rectilinear profile with a constant flow rate.

• 설비공학논문집
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• 제15권9호
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• pp.727-732
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• 2003

In the present study, a PIV measurement and image processing technique were applied in order to investigate the flow characteristics in the gas injected liquid bath. The circulation of liquid was induced by upward bubble flow. Due to the centrifugal force, the flow was well developed near both wall sides than in the center of a bath. The vortex flow irregularly repeated generation and disappearance which helped to accelerate the mixing process. The bubble rise velocity in the bottom region was relatively lower than in the upper region because the energy generated by bubbles' behavior in the region near the nozzle was almost converted into kinetic energy But bubble rise velocity increases with the increase of the axial distance since kinetic energy of rising bubbles is added to buoyancy force. In conclusion, the flow increased bubble rise velocity and the flow of the bottom region became more active.