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이주희(Juhee Lee),유근열(Keun-yeal You),박경우(Kyoungwoo Park) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Shape optimization of the 3-dimensional WIG airfoil with 3.0-aspect ratio has been performed by using the multi-objective genetic algorithm. The WIG ship effectively floating above the surface by the ram effect and the virtual additional aspect ratio by a ground is one of next-generation and cost-effective transportations. Unlike the airplane flying out of the ground effect, a WIG ship has possibility to capsize because of unsatisfying the static stability. The WIG ship should satisfy aerodynamic properties as well as a static stability. They tend to strong contradict and it is difficult to satisfy aerodynamic properties and static stability simultaneously. It is inevitable that lift force has to scarify to obtain a static stability. Multi-objective optimization technique that the individual objectives are considered separately instead of weighting can overcome the conflict. Due to handling individual objectives, the optimum cannot be unique but a set of nondominated potential solutions: pareto optimum. There are three objectives; lift coefficient, lift-to-drag ratio and static stability. After a few evolutions, the non-dominated pareto individuals can be obtained. Pareto sets are all the set of possible and excellent solution across the design space. At any selections of the pareto set, these are no better solutions in all design space.
단순화법을 이용한 소성 경화재료에서의 탄ㆍ소성 구조물의 유한요소해석
김병삼(Byeong-Sam Kim),박경우(Kyoungwoo Park),성기석(Kisuk Sung),유근열(Geunyeal YU) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
A simplified finite element analysis method is proposed to calculate elasto-plastic responses of general hardening materials. The method provides an effective tool to calculate structural elasto-plastic responses. Numerical examples have demonstrated that its computational efficiency is very much higher than that of the incremental elasto-plastic finite element analysis, and computational results are accurate enough to meet the need of engineering practice. Compared with the general elasto-plastic incremental finite element analysis, the proposed method can avoid the incremental iteration of nodal displacements and the constitutive equation integration at each Gauss integral point, and computational results are accurate enough to meet the need of engineering practice.
박경우(Kyoungwoo Park),임효재(Hyo Jae Lim),권정태(Jeong Tae Kwon),이주희(Juhee Lee),유근열(Keun Yeol Yu) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
An optimal shape for a paper machine headbox can improve the paper quality and increase the production speed, simultaneously. In the present work, the optimization of headbox shape is carried out by integration CFD and optimization algorithm. The shape of the baseline headbox is parameterized and rebuilt with four-Bezier curves. Each Bezier curve is composed of five control points. The range of design variables and their resolutions are two primary keys for the successful optimization. In the paper machine headbox, the optimum values of the design variables can be achieved when the deviation of flow rate at each tube and the amount of return flow at exit are minimized, simultaneously. To complete the optimization, the finite volume method for calculating the objective functions and a multi-objective genetic algorithm for carrying the optimization process are used, respectively. After twenty-five evolutions, the non-dominated Pareto individuals can be obtained.