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이홍우,Lee, Hong-Woo 한국공간구조학회 2008 한국공간구조학회지 Vol.8 No.3
본 연구에서는 방향벡터(direction vector)를 이용한 지역 탐색법과 유전자 알고리즘을 결합한 새로운 알고리즘인 D-GA를 제안한다. 새로운 개체(individual)를 찾기 위한 방향벡터로는 진화과정 중에 습득되는 정보를 활용하기 위한 학습방향벡터(Loaming direction vector)와 진화와는 무관하게 한 개체의 주변을 탐색하는 랜덤방향벡터(random direction vector) 등 두 가지를 구성하였다. 그리고, 10 부재 트러스 설계 문제에 단순 유전자 알고리즘과 D-GA를 적용하여 최적화를 수행하였고, 그 결과를 비교 검토함으로써 단순 GA에 비하여 D-GA의 정확성 및 효율성이 향상되었음을 확인하였다. In this study, the modified genetic algorithm, D-GA, is proposed. D-GA is a hybrid genetic algorithm combined a simple genetic algorithm and the local search algorithm using direction vectors. Also, two types of direction vectors, learning direction vector and random direction vector, are defined without the sensitivity analysis. The accuracy of D-GA is compared with that of simple genetic algorithm. It is demonstrated that the proposed approach can be an effective optimization technique through a minimum weight structural optimization of ten bar truss.
이홍우(Lee Hong Woo) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
A robust and efficient numerical analysis of thin elastic shells and plates has been a great challenging subject in the computational mechanics community, so that intensive research efforts have focused on the development of numerical formulation and finite element for several decades to achieve this goal. Nevertheless, several numerical difficulties such as numerical locking still leave this goal unsatisfactory and require further refinement. A representative refinement is a rotation-free plate and shell element introduced more recently, in which each node contains only the degrees-of-freedom of in-plane displacement part and the rotation part is interpolated indirectly. The main purpose of this study is to explore the applicability of the natural element method for the efficient and robust analysis of thin elastic plates. The complicated plate domain is discretized efficiently by Delaunay triangulation and the deflection field is more accurately approximated with Laplace interpolation functions. Only one deflection becomes DOF of each node, while the curvature is interpolated by area-averaging the high-order derivatives of the deflection. Meanwhile, the stabilized conforming nodal integration incorporated with Voronoi diagram is employed to have the deflection field satisfy the integration constraint. The validity of the proposed method is examined through the numerical experiments.
이홍우(Lee Hong-Woo),조종수(Cho Jong-Soo) 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2
Pedestrian space has been changed by the change of urban structure and our urban structure became a double-layered structure which is traditional and modem street are overlapped. Urban planning centering on automobiles threatened pedestrians' safety and created deteriorated Urban street surroundings. A study centering on pedestrians will make them regain the right of pedestrians who are driven out of their space by automobiles, and will make you recognize that street is not just a passageway but space of living. What to find space for pedestrians and to grasp consciousness characteristic of pedestrians can act as a factor to reforms urban planning centering on automobiles. The purpose of this study is to make urban space development by the considering a street and pedestrian space for a stable urban structure and pedestrian space in Korea.
이홍우(Hong Woo Lee),강연식(Yeon Sik Kang),김재현(Jaehyun Kim) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
This paper presents topology optimization as a tool for structural lay-out design of auto body, especially underbody. BESO(bi-directional evolutionary structural optimization) based on finite element method is applied to create optimal lightweight underbody under various external load conditions. In order to treat multi-load condition, weighted average objection function was introduced. According to the numerical formulae, a PC-based test program is coded in Fortran. To verify the proposed test program, the numerical results on several benchmark problems are compared with those obtained by references. The validity of the topology optimization is examined through the numerical examples on EV(electric vehicle) underbody concept design.
이홍우(Hong-Woo Lee),최주형(Joo-Hyoung Choi),조진래(Jin-Rae Cho) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Weather Strip(W/S) is a rubber part to proof water, sound and dust for opening and shutting devices including vehicle doors. Thus, it is required that the W/S has the high dimension precision and considerable durability. The accurate analysis on the thermal flow of the rubber material is necessary to produce W/S which satisfies these requirements. In this paper, we focus on the numerical thermal flow analysis for the extrusion forming of W/S. Through parametric simulations, the eddy thermal flow characteristics of rubber materials in the extrusion forming process are investigated.
이홍우(Hong-Woo Lee),조진래(Jin-Rae Cho) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
According to our previous study, it is confirmed that the Petrov-Galerkin natural element method (PGNEM) completely resolves the numerical integration inaccuracy in the conventional Bubnov-Galerkin natural element method (BG-NEM). This paper is an extension of PG-NEM to two-dimensional nonlinear dynamic problem. For the analysis, a constant average acceleration method and a linearized total Lagrangian formulation is introduced with the PG-NEM. At every time step, the grid points are updated and the shape functions are reproduced from the relocated nodal distribution. This process enables the PG-NEM to provide more accurate and robust approximations. The representative numerical experiments performed by the test Fortran program, and the numerical results confirmed that the PG-NEM effectively and accurately approximates the nonlinear dynamic problem.