• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.81-85
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• 2005

Three-dimensional steady incompressible laminar entry flows in a square duct of $90^{\circ}$ bend are numerically simulated by a new solution code(PowerCFD) using unstructured cell-centered method. Solutions are obtained with three unstructured grid types of hexahedron, prism and hybrid at a Reynolds number, based on the hydraulic diameter and bulk velocity, of 790. Interesting features of the flow are presented in detail. Detailed comparisons between the computed solutions and the available experimental data are given mainly for the velocity distributions at cross-sections in a $90^{\circ}$ bend of a square duct with fully-developed entry flows. It is found that the code is capable of producing the nature of laminar flow in curved square duct with no grid type dependency.

• 대한기계학회논문집B
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• 제20권9호
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• pp.2916-2923
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• 1996

A numerical analysis of the moving bed heat exchanger of solid particles inside the vertical pipe was performed using finite difference method. Also, the theoretical solutions were obtained for comparison when the wall heat flux or the wall temperature was assumed constant. The comparison showed that their results agreed well each other. The moving bed heat exchanger was classified as countercurrent-flow, parallel-flow, and cross-flow types according to the gas flow direction. For each type, the thermal efficiency of heat exchanger was calculated as a function of non-dimensional parameters such as the characteristic length of heat exchanger, Biot number and the ratio of thermal capacities of gas and solid particles.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.312-315
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• 2008

The flow structure behind circular and elliptical type rings embedded in a cross-flow was investigated experimentally using two-frame particle image velocimetry (PIV). The experiments were performed in a circulating water channel with a test section of 0.35m height ${\times}$ 0.3m width ${\times}$ 1.1m length. PIV measurements were carried out with varying the Reynolds number in the range of 4.5 ${\times}$ $10^2$ - 4.5 ${\times}$ $10^3$. In the present study, turbulent flow structures in the stream-wise direction and span-wise direction were investigated. The mean velocity field distribution was obtained by statistical-averaging instantaneous velocity fields. The spatial distributions of turbulent statistics such as turbulent intensities and turbulent kinetic energy were also investigated.

• 한국공간구조학회논문집
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• 제16권2호
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• pp.69-77
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• 2016

The purpose of this study is to present a method that can estimate the height of reaction facilities for large structural experiment through load flow as primary design procedure. The characteristic of the load transmission according to the type of experiment was analyzed to obtain tensile and compressive forces occurring on the reaction facilities. Strong walls that are affected by the bending moment is applied the post-tensioning method, and the strong floor under the control of the tension and compression is designed in accordance with the load flow. And the optimum cross-section of the reaction facilities was obtained by comparing the stresses of the tensile stress and crack the concrete. Through validating elastic analysis, the design results were satisfied a given design conditions.

• 한국수자원학회논문집
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• 제46권9호
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• pp.947-956
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• 2013

급경사 산지하천 수충부의 호안은 대부분 콘크리트 옹벽으로 되어있다. 표면이 매끄러운 콘크리트 옹벽호안은 유속을 더 강화시키기 때문에 수충부 홍수피해의 원인이 되기도 한다. 본 연구에서는 개수로의 한 측벽에 설치한 정사각형 단면의 세로돌출줄눈이 흐름저항에 미치는 영향을 파악하기 위해 수리실험을 수행하였다. 돌출줄눈의 설치간격은 무차원 돌출줄눈 간격 ${\lambda}_{nv}$를 기준으로 조도유형 d형과 k형을 포함하도록 설계하였다. 흐름의 Froude 수는0.81~1.12의 범위였다. 흐름저항은 돌출줄눈의 설치간격과 유량에 좌우되었다. ${\lambda}_{nv}$가 9일 때 흐름저항이 가장 큰 것으로 나타났다. 세로돌출줄눈은 유량이 증가하면 d형 조도에서는 흐름저항을 감소시켰으나 k형 조도에서는 흐름저항을 증가시켰다. 흐름저항의 증가폭은 ${\lambda}_{nv}$이 9~12의 범위에서 상대적으로 더 크게 나타났다. 세로돌출줄눈에 의한 흐름저항은 대부분 형상저항에 의한 것이며 그 등가조도높이는 수심규모로 발생할 수 있고 흐름저항에 미치는 영향이 매우 크다. 측벽의 세로돌출줄눈은 흐름저항을 증가시키고 최대유속의 발생위치를 수로의 횡단면 중앙방향으로 이동시키는 수단으로 사용될 수 있을 것이다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.165.2-165.2
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• 2011

Dye to recent development such as increasing price of fossil fuels and energy offers such a solution. Wave energy supplies. Weve energy offers such a solution. Wave energy is the most consistent of all the intermittent renewable energy sources. In addition to this, very large energy fluxes occur in the ocean waves and by using appropriate wave energy converters the energy can be harnessed. The present study looks at utilizing a direct drive turbine of cross flow type to extract energy from ocean waves indirectly. This novel design incorporates a turbine in an enclosed in a closed tank. utilizing the energy generated from sloshing.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.691-696
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• 2000

Cooling characteristics of cooling jacket for spindle system with built-in motor are studied. Three dimensional model was selected for the analysis of the helical-type cooling jacket. This model includes the estimation on the amount of heat generation from bearing and built-in motor and the thermal characteristic values such as heat flux on the boundary. The temperature distributions are analyzed and the cooling by Nusselt number and total heat transfer coefficient. Numerical results show that stream-wise cross section area and flow rate are important factors for cooling characteristics of cooling jacket.

• 한국수소및신에너지학회논문집
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• 제30권2호
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• pp.147-154
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• 2019

In this study, effects of flow types and size of molten carbonate fuel cells (MCFCs) were investigated using CFD simulation. In the simulation, the current collector of MCFCs were assumed to be an porous media. With the area of $0.09m^2$, the effect of flow types such as Co-flow, Counter-flow, Cross-flow were studied. After that the effect of the size and flow direction was studied. Among three-flow types, MCFCs with co-flow type shows more uniform distribution and current density distribution.

• 한국터널지하공간학회 논문집
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• 제19권2호
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• pp.213-229
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• 2017

최근 도심지 터널은 진출입 Ramp를 포함한 다양한 형태의 네트워크형 터널이 건설되고 있다. 더불어 터널환기 해석을 위한 다양한 네트워크 이론 기반의 1D 프로그램들이 개발되고 있다. 본 연구에서는 비 hardy-cross 법에 기초한 네트워크형 터널에 대한 풍량 및 농도해석이 가능한 프로그램을 개발하였다. 터널 구간내 풍량해석은 Gradient 법에 기초하고 있으며, 농도해석을 위하여 복잡한 네트워크 구조에서 유입과 유출농도를 자동계산 할 수 있는 로직을 개발하였고, 저속풍량구간에서는 수치해석적 오차를 축소시키기 위한 적정 그리드 간격을 제시하였다. 또한, 프로그램의 적정성을 검증하기 위해, 일자형 터널을 대상으로 고전적인 Sokic의 풍속 선도법 및 TVSDM 프로그램과의 풍속비교검증을 수행하였으며 오차율은 1% 이하였다. 또한 최근 건설되는 도심지 터널에 적용중인 최신 환기방식에 대한 네트워크 환기해석을 수행하였다.

• 한국전산유체공학회지
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• 제21권2호
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• pp.99-105
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• 2016

The present study has been carried out to analyze the flow characteristics with geometric shape and control conditions in subsea by-pass valve. The function of by-pass valve is to prevent reverse flow. In this study, the static analysis has been perform for analyzing fluid flow in open state. In order to consider the turbulent effect, the standard ${\kappa}-{\varepsilon}$ model was used. A variety of parametric studies, such as by-pass valve type or size, volume flow rate, leakage hole size, leakage hole position, block type, block shape, were performed. The pressure difference across the valve in the model broadened the flow channel cross-sectional area was greater than the base model for the same operating conditions. As the pipe diameter in the block decreases the pressure difference is greatly increased. The pressure difference according to block shape such as edge type and round was almost negligible. For the same Reynolds number the pressure difference was little changed according to the size of the valve.