• 한국산학기술학회논문지
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• 제13권5호
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• pp.1963-1968
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• 2012

본 논문은 현장에서 사용하고 있는 밸브 수압측정기를 3차원 자동설계 프로그램인 CATiA를 활용하여 설계하였다. 또한 유한요소 해석코드인 ANSYS를 활용하여 설계된 밸브 수압측정기에 대하여 유동해석을 수행하여 내부압력에 따른 유체의 흐름을 구하였다. 이러한 해석결과는 새로운 밸브 수압측정기를 개발하는데 기초자료로 활용될 계획이며 개발예정인 밸브 수압측정기는 밸브 점검 시 시간을 단축하고, 사고를 방지하여 안전성을 향상시킨다.

• 국제초고층학회논문집
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• 제11권4호
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• pp.321-329
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• 2022

High-rise buildings constructed adjacent to low-rise structures experience frequent damage caused by the associated strong wind. This study aimed to implement a standard evaluation of the wind environment and airflow characteristics around high-rise apartment blocks using wind tunnel tests (WTT) and computational fluid dynamics (CFD) simulations. The correlation coefficient between the CFD and wind tunnel results ranged between 0.6-0.8. Correlations below 0.8 were due to differences in the wake flow area range generated behind the target building according to wind direction angle and the effect of the surrounding buildings. In addition, a difference was observed between the average velocity ratio of the wake flow wind measured by the WTT and by the CFD analysis. The wind velocity values of the CFD analysis were therefore compensated, and, consequently, the correlations for most wind angles increased.

• Korean Chemical Engineering Research
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• 제48권3호
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• pp.337-341
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• 2010

직경 1 m, 높이 1 m의 교반탱크 내 유체흐름 패턴을 상용 전산유체역학 프로그램의 하나인 CFX를 사용하여 해석함으로써 교반속도, 임펠러 회전날개의 경사각, 방해판의 존재 유무, 탱크바닥 형태가 흐름패턴에 미치는 영향을 알아보았다. 방해판이 없을 경우 탱크 중심에서 와류가 관찰되었으며 교반속도가 증가함에 따라 탱크 중심의 와류 현상이 증가하였으나, 방해판 설치에 의해 와류가 감소하였다. 임펠러 날개의 경사각을 증가시킴으로써 교반탱크 상하로의 유체흐름이 증가하였고 와류도 감소하였다. 탱크바닥을 수평으로 하는 것 보다 둥글게 함으로써 탱크 바닥 구석에서 유체흐름이 원활하게 변화하였다.

• International Journal of Vascular Biomedical Engineering
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• 제2권1호
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• pp.11-16
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• 2004

Both flow visualizations and computational fluid dynamics were performed to determine hemodynamics in a total cavopulmonary connection (TCPC) model for surgically correcting congenital heart defects. From magnetic resonance images, an anatomically correct glass model was fabricated to visualize steady flow. The total flow rates were 4, 6 and 8L/min and flow rates from SVC and IVC were 40:60. The flow split ratio between LPA and RPA was varied by 70:30, 60:40 and 50:50. A pressure-based finite-volume software was used to solve steady flow dynamics in TCPC models. Results showed that superior vena cava(SVC) and inferior vena cava(IVC) flow merged directly to the intra-atrial conduit, creating two large vortices. Significant swirl motions were observed in the intra-atrial conduit and pulmonary arteries. Flow collision or swirling flow resulted in energy loss in TCPC models. In addition, a large intra-atrial channel or a sharp bend in TCPC geometries could influence on energy losses. Energy conservation was efficient when flow rates in pulmonary branches were balanced. In order to increase energy efficiency in Fontan operations, it is necessary to remove a flow collision in the intra-atrial channel and a sharp bend in the pulmonary bifurcation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.572-575
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• 2008

Flow-field design has much influence over the performance of proton exchange membrane fuel cell (PEMFC) because it affects the pressure magnitude and distribution of the reactant gases. To obtain the pressure magnitude and distribution of reactant gases in four kinds of flow-field designs without additional measurement equipment, computational fluid dynamics (CFD) analysis was performed. After the CFD analysis, the performance values of PEMFC according to the flow-field configurations were measured via a single cell test. As expected, the pressure differences due to different flow-field configurations were related to the PEMFC performance because the actual performance results showed the same tendency as the results of the CFD analysis. A large pressure drop resulted in high PEMFC performance. So, the single serpentine configuration gave the highest performance. On the other hand, the parallel flow-field configuration gave the lowest performance because the pressure difference between inlet and outlet was the lowest.

• 한국전산유체공학회지
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• 제18권2호
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• pp.99-108
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• 2013

The standard drag force and virtual mass force, which exert to the primary flow direction, are generally considered in two-phase analysis computational codes. In this paper, the lift force, wall lubrication force, and turbulent dispersion force including turbulence models, which are essential for a computational multi-fluid dynamics model and play an important role in motion perpendicular to the primary flow direction, were introduced and verified with conceptual problems.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.652-653
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• 2009

In this study, flow-induced vibration (FIV) analyses have been conducted for a 3D compressor blade model. Advanced computational analysis system based on computational fluid dynamics (CFD) and computational structural dynamics (CSD) has been developed in order to investigate detailed dynamic responses of designed compressor blades. Fluid domains are modeled using the computational grid system with local grid deforming and remeshing techniques. Reynolds-averaged Navier-Stokes equations with $\kappa-\varepsilon$ turbulence model are solved for unsteady flow problems of the rotating compressor model. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3D compressor blade for fluid-structure interaction (FSI) problems. Detailed dynamic responses and instantaneous pressure contours on the blade surfaces considering flow-separation effects are presented to show the multi-physical phenomenon of the rotating compressor blade.

• 한국소음진동공학회논문집
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• 제19권6호
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• pp.551-559
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• 2009

In this study, flow-induced vibration(FIV) analyses have been conducted for a 3D compressor blade model. Advanced computational analysis system based on computational fluid dynamics(CFD) and computational structural dynamics(CSD) has been developed in order to investigate detailed dynamic responses of designed compressor blades. Fluid domains are modeled using the computational grid system with local grid deforming and remeshing techniques. Reynolds-averaged Navier-Stokes equations with $\kappa-\epsilon$ turbulence model are solved for unsteady flow problems of the rotating compressor model. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3D compressor blade for fluid-structure interaction(FSI) problems. Detailed dynamic responses and instantaneous pressure contours on the blade surfaces considering flow-separation effects are presented to show the multi-physical phenomenon of the rotating compressor blade.

• Journal of Advanced Marine Engineering and Technology
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• 제36권5호
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• pp.609-617
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• 2012

The flow characteristics of polluted air are analysed by comparing the results obtained from PIV(Particle Image Velocimetry) experiment and CFD(Computational Fluid Dynamics) commercial code. In order to simulate the polluted air flow, the olive oil has been used as tracer particles with the kinematic viscosity of air, $1.51{\times}10^{-5}m^2/s$. The investigation has done in the range of Reynolds numbers of 870, 1730 and 2890 due to the inlet flow velocities of 0.3, 0.6, and 1.0 m/s, respectively. The average velocity and the pressure distributions are comparatively discussed with respect to the three different Reynolds numbers. The results show that the outlet flow rates at three different Reynolds numbers are equivalent of 165 to 167 percent of the inlet ones. The pressure drop occurs in the model closed at both end sides and the highest pressures at each Reynolds number are positioned at the top of the tunnel between the inlet and outlet.

• 디지털융복합연구
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• 제11권8호
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• pp.199-204
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• 2013

단순한 모델링이 아닌 3차원의 정밀한 모델링을 이용하여 연료전지 내부에서의 상황을 모사하였다. 자동차 엔진, 비행기 등의 설계에 있어서 실제 실험의 횟수를 줄여주기 위하여 매우 정밀한 전산유체역학(CFD)이 사용된다. 본 연구에서는 CD-ADAPCO사의 STAR-CD를 이용하여 고체고분자전해질형 연료전지(PEMFC)의 성능을 분석하였다. PEMFC 단위전지의 형상과 유로의 흐름의 변화에 따른 성능의 영향성을 분석하였다. 그 결과 rectangular cell 의 성능이 square cell 보다 높게 나타났으며 유체흐름의 방향은 성능에 큰 영향을 미치지 못했다. 또한 공기의 과잉률에 따른 전체적인 연료전지의 성능을 비교하였으며, 또한 PEMFC 내부에서의 전류밀도의 분포에 관한 분석을 실시하여 그 결과를 비교, 분석하였다. 그 결과 flip-flow의 경우가 co-flow의 경우에 비하여 최대치와 최고치의 값의 편차가 작은 것으로 확인되어 보다 균일한 분포를 가지는 것을 확인할 수 있었다.