• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.131.1-131
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• 2001

• Journal of the Microelectronics and Packaging Society
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• v.8 no.4
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• pp.67-72
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• 2001

An Effort has been made to more accurately analyze the flow in the chip cavity, particularly to model the flow through the openings in the leadframe and correctly treat the thermal boundary condition at the leadframe. The theoretical analysis of the flow has been done by using the Hele-Shaw approximation in each cavity separated by a leadframe. The cross-flow through the openings in the leadframe has been incorporated into the Hele-Shaw formulation as a mass source term. The optimization program based on the complex method integrated with flow analysis program has been successfully used to obtain the optimal filling conditions to avoid short shot.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1139-1146
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• 2012

An alternative approach for topology optimization of steady incompressible Navier-Stokes flow problems is presented by using P1 nonconforming finite elements. This study is the extended research of the earlier application of P1 nonconforming elements to topology optimization of Stokes problems. The advantages of the P1 nonconforming elements for topology optimization of incompressible materials based on locking-free property and linear shape functions are investigated if they are also valid in fluid equations with the inertia term. Compared with a mixed finite element formulation, the number of degrees of freedom of P1 nonconforming elements is reduced by using the discrete divergence-free property; the continuity equation of incompressible flow can be imposed by using the penalty method into the momentum equation. The effect of penalty parameters on the solution accuracy and proper bounds will be investigated. While nodes of most quadrilateral nonconforming elements are located at the midpoints of element edges and higher order shape functions are used, the present P1 nonconforming elements have P1, {1, x, y}, shape functions and vertex-wisely defined degrees of freedom. So its implentation is as simple as in the standard bilinear conforming elements. The effectiveness of the proposed formulation is verified by showing examples with various Reynolds numbers.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.668-670
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• 2012

본 논문에서는 시작엔진 제작에 앞서 CFD기법을 이용하여 디젤 엔진 흡기포트의 유동 특성을 분석하고자 하였다. 유동 해석 결과 높은 밸브리프트에서는 흡기포트 곡률 최적화로 인해 흡입 공기량이 극대화되었으며, 낮은 밸브리프트에서는 스월 Chamfer를 적용하여 스월유동이 강화된 것을 확인할 수 있었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.61-65
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• 2011

In this paper, the nozzle design with asymmetric configuration using the optimal method is used in order to improve the under- and over-expansion problem of the flow at the supersonic turbine nozzle. For the design of nozzle contour, 8 design variables are selected and the total-to-static efficiency from the nozzle inlet to the wake outlet is considered as the objective function to be maximized. The Fluent6.3 and the iSIGHT-FD program are used for calculation of nozzle flow and design optimization respectively. RBF(Radial Basis Function) method is chosen for approximate optimization algorithm. It is shown that the static efficiency of improved nozzle design increases 1.35% and loss coefficient decreases 19.85% as compared to baseline design.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.66-70
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• 2007

현재 많은 연구들이 작은 크기에 여러 공정을 집적시킬 수 있는 장점을 가진 마이크로 장치의 개발과 활용에 집중되고 었다. 마이크로 장치에서 가장 중요한 것은 미세 유동의 효율적인 제어이다. 본 연구에서는 마이크로 장치에 직접 적용 가능한 표면 개질 된 마이크로 채널의 유동에 대하여 고려하였다. 표면 개질(surface treatment)은 물리적, 화학적인 작용을 통해서 채널 내부 표면의 습윤성을 변화시켜 유동을 제어하는 방법이다. 친수성(glass)을 가지는 마이크로 채널 내부의 일부를 소수성(teflon)으로 개질 후, 고속카메라를 이용하여 채널 내부를 흐르는 유체의 유동 경계면 변화를 분석하였다. 또한 유동 해석을 위한 상용 코드(CFD-ACE)를 이용하여 유동에 대한 수치 해석을 진행하여 가시화된 실험 결과와 비교 분석하였다. 실험 결과와 수치 해석 결과를 통해, 친수성과 소수성 표면 배열에 따른 일시적인 유동 변화를 관찰하였다. 본 연구 결과를 통해 마이크로 채널 유동의 최적화 상태를 찾을 수 있으며, 보다 용이한 미세 유동 제어가 가능하다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5968-5973
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• 2014

The gate location in injection molding has a significant influence on the quality and productivity. Therefore, injection molding CAE is used to determine the gate location. With increasing injection molding CAE and the adoption of a 3D mesh, which takes more computation time for analysis, gate location optimization in the shortest time and least resources is the most challenging issue. In this paper, we propose a methodology for optimization based on the flow length to consider the flow balance and weld line. In addition, the flow balance is obtained in the disc-type plate while the weld lines exit the slit-holes to avoid a stress concentration.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.303-307
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• 2009

Secondary flow losses can be as high as $30{\sim}50%$ of the total aerodynamic losses generated in the cascade of a turbine. Therefore, these are important part for improving a turbine efficiency. As well, many studies have been performed to decrease the secondary flow losses. The present study deals with the leading edge fences on a wing-body to decrease a horseshoe vortex, one of the factors to generate the secondary flow losses, and optimizes the shape of leading-edge fence with the shape factors, such as the installed height, length, width, and thickness of the fence as the design variables. The study was investigated using $FLUENT^{TM}$ and $iSIGHT^{TM}$. Total pressure loss coefficient was improved about 7.5 % than the baseline case.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.525-528
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• 2011

1400cc급 발전용 엔진 트로틀 바디의 최적화 및 성능 향상을 위하여 유동해석을 수행하였다. 베르누이 정리를 기본으로, 성능을 발휘하는 주요 설계인자인 트로틀 바디 내부의 트로틀 밸브 각도 및 흡기부 곡률 등을 설계 변수로 유동해석을 수행하였다. 벤튜리관 흡입부의 곡률을 증가시켜 트로틀 바디에서 소모되는 흡기저항을 줄였다. 감소된 흡기저항은 펌핑로스를 저감하여 연비향상에 도움이 될 것으로 기대된다. 결과적으로 해석결과 분석을 통하여 최적화된 모델을 제시하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.25-35
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• 2012

An endwall boundary layer fence technique was adapted to improve the aerothermal environment of a gas turbine passage. The shape optimization of the fence was performed to maximize the improvement. The turbine passage was simulated by a $90^{\circ}$ turning duct (ReD=360,000). The main purpose of the present investigation was to focus on finding a endwall boundary layer fence with minimum total pressure loss in the passage and heat transfer coefficient on the endwall of the duct. Anothor objective function was to minimize the area on the endwall of the duct. An approximate optimization method was used for the investigation to secure the computational efficiency. Results indicated that a significant improvement in aerodynamic environment can be achieved through the application of the fence. Improvement of the thermal environment was smaller than that of the aerodynamic enviroment.