• 한국유체기계학회 논문집
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• 제3권1호
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• pp.19-27
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• 2000

A numerical study is presented for analysis of three-dimensional incompressible turbulent flows in a multi-blade centrifugal fan. Reynolds-averaged Navier-Stokes equations with a standard $k-{\espilon}$ turbulence model are discretized with finite volume approximations. The computational area is divided into three blocks; inlet core, impeller and scroll parts, which are linked by a multi-block method. The flow inside of the fan is regarded as steady flow, and the mathematical models for the impeller forces were established from a cascade theory and measured data. Empirical coefficients are obtained comparing between computational and experimental results for the case without scroll, and are employed to simulate the flow through the impeller with scroll. In comparisons with experimental data, the validity of the mathematical models for the impeller forces was examined. The characteristics of the flow in the scroll were also discussed.

• 대한조선학회지
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• 제24권3호
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• pp.9-16
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• 1987

In this paper, the fluid flow in the two-dimensional tank is analyzed by the Finite Difference Method. The Navier-Stokes equation is modified for the tank fixed coordinate system. For the treatment of the free surface, the Volume of Fluid Method by Hirt and Nichols is adopted. The continuity equation and the Poisson equation which is derived from the Navier-Stokes equation to find the pressure are solved by the Successive-Line-Overrelaxation Method. The comparison of the calculated results with experimental data show a favorable agreement. The fluid flow in the two-dimensional tank can be predicted reasonably before the free surface reaches breaking by this numerical method.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.167-173
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• 2010

In this study, flow structure in a three-stage centrifugal compressor for LNG Plant with the refrigerant, Propane, was numerically investigated at the design point of the compressor using a commercial code. Flow characteristics in the passages of impeller and vaneless diffuser were analyzed in detail including velocity vector, Mach number and pressure contours in blade spanwise and meridional plane for each stage. The estimation on the one-dimensional output from the preliminary design and three-dimensional shape of the impeller blade was performed through the flow analysis. The verification for designed compressor was carried out from three-dimensional Navier-Stokes analysis. The results will be used as reference data for a new design of 3-D impeller shape to improve propane refrigerant compressor performance.

• 대한기계학회논문집A
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• 제20권5호
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• pp.1486-1497
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• 1996

The problem of determining the 3-demensional motion of any two rough bodies after a collision involves some rather long analysis and yet in some points it differs essentially from the corresponding problem in tdwo dimensions. We consider a special problem where two rough ellipsolids moving in any manner collide, and analyze the three dimensional impact process with Coulomb friction and Poisson's hypothesis. The differential equations that describe that process of the impact induce a flow in the tangent velocity space, the flow patterns characterize the possible impact cases. By using the graphic method in impulse space and numerical integration thchnique, we analyzed the impact process inall the possible cases and presented the algorithm for determining the post-impact motion. The principles could be applied to the general problem in three dimensions. We verified the effectiveness of the analysis results by simulating the numerous significant examples.

• 인지과학
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• 제22권3호
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• pp.299-326
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• 2011

소설, 블로그, 채팅 메시지, 상품평 등의 텍스트는 전반적인 정서의 흐름을 가지고 있다. 텍스트 간의 정서 흐름의 유사도를 비교하면 유사한 정서 흐름을 갖는 텍스트를 분류할 수 있고, 상품 추천이나 의견 수집 등에 활용할 수 있다. 본 논문에서는 텍스트에서 정서 단어를 순차적으로 추출하고 쾌-불쾌, 활성화의 2차원으로 분석하여 텍스트의 정서 흐름을 파악하였다. 또한 텍스트의 순차적인 흐름을 시간 차원으로 설정하여 텍스트의 전반적인 정서 흐름인 '지배 정서(dominant emotion)'를 파악하기 위하여 쾌-불쾌, 활성화, 시간의 3차원 공간에서 정서 흐름을 탐색하였다. 또한 이 3차원 공간 안에서 유클리드 거리를 사용하여 지배 정서 흐름의 유사도를 계산함으로써 유사한 정서 흐름을 가지는 텍스트를 분류하는 방법을 제안하였다. 제안한 방법을 통해 한국 근대 단편 소설들을 분석하여 지배 정서를 분석하였고 유사한 지배 정서를 가지는 소설들을 분류하였다.

• 설비공학논문집
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• 제6권4호
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• pp.337-343
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• 1994

Numerical analysis was applied to a simplified two-dimensional Ondol heating model which consists of heating space on the top of it along with radiant and convective heating floor panel, flue channel in the midway and rectangular underground soil region at the bottom. These three components constitute a system thermally coupled at the top and bottom interfaces of the flue channel. Investigated in the present paper are effects with variations of the Reynolds numbers of 100, 200, and 300, Grashof numbers of $0.1{\times}10^6$ and $0.3{\times}10^6$ and aspect ratios of 15 and 20 on the heat transfer and fluid flow characteristics of two-dimensional Ondol heating model by computer simulation.

• 동력기계공학회지
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• 제19권4호
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• pp.36-42
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• 2015

TMixed convective flow in a bottom heated and top cooled rectangular channel can be significantly affected by the channel aspect ratio, Prandtl number, Reynolds number, Rayleigh number and angle of inclination. In such a mixed convection, the flow pattern plays an important role in various technological processes. In this study, a numerical investigation is carried out to explore mixed convection in a three-dimensional rectangular channel with bottom heated and top cooled uniformly. The three-dimensional governing equations are discretized using the finite volume method. In the range of low Reynolds number($0{\leq}Re{\leq}9.6{\times}10^{-2}$), the effects of the aspect ratio($2{\leq}AR{\leq}12$) and Gr/Re are presented and discussed. The longitudinal roll number in the channel is increased with increasing aspect ratio, and the roll number induced, regardless of the aspect ratio number, is even in the range of aspect ratios between 2 and 12, New vortex flow structure containing inclined longitudinal rolls is found, which is affected by aspect ratio and Reynolds number. The ratio Gr/Re is used to check the relative magnitudes of forced and natural convection in the mixed convective flow of high viscous fluid.

• 한국유체기계학회 논문집
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• 제4권3호
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• pp.14-20
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• 2001

Numerical analysis of the three dimensional turbulent flow field in a complex valve trim is carried out to confirm the possibility whether this simulation tool can be used as a design tool or not. The simulation of the incompressible flow in a glove valve is performed by using the commercial code. CFD-ACEA utilizes the finite volume approach as a discretization scheme, and the pressure-velocity coupling is made from SIMPLEC algorithm in it. Four flow cases of the control valve are investigated, and the valve flow coefficient for each case is compared with the experimental data. Simulation results show a good agreement with the experiments, and it is observed that the cavitation model improves the simulation results.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2003년도 춘계학술발표대회 요약집
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• pp.125-125
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• 2003

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 추계학술발표회요약집
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• pp.167-167
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• 2002