모티프를 이용한 최적설계 통합환경 개발

임오강,조헌,김영현,이병우 釜山大學校生産技術硏究所 1998 生産技術硏究所論文集 Vol.55 No.-

본 연구에서는 모티프(Motif), ANCI-C, Fortran 언어를 사용하여 그래픽 입출력과 대화식 입력이 가능하며, 최적설게 수행에 필요한 모든 작업을 같이 병행할 수 있는 최적설계 통합환경을 개발하였다. 최적설계 통합환경은 전처리기(Preprocessor), 최적설계부, 후처리기(Postprocessor)로 구성하였다. 전처리기에서는 유한요소 모형의 구성에 필요한 정보를 입력한 후 사용자가 입력한 정보를 즉시 확인할 수 있도록 하였다. 최적설계부에서는 전처리기에서 입력한 유한요소 정보를 바탕으로 최적설계 매개변수를 정의하고, 해를 구하는 과정으로 구성하였다. 후처리기에서는 구조물의 변형, 응력, 목적함수의 변화등의 해석 결과를 가시화 함으로써 결과에 대한 비교·검토를 용이하게 하였다. An integrated environment for optimum design has been developed using Motif. The integrated environment is composed of the preprocessor, the postprocessor and the optimization part. The preprocessor is part of making a finite element model for optimum structural design and the postprocessor displays results of optimum design and the optimization part is the part which execute opimization. It is designed to reduce user's difficulties in structural optimum design. It used Graphic User Interface for the concurrent representation of various inputs and outputs through the dialog box, mouse and keyboard. Structural optimum design can be done easily through dialog box, menu, concurrent representation of modeling process and results of structural optimum design can be understood easily through stress contour, deformed model and graph of cost function.

Initial Design Domain Reset Method for Genetic Algorithm with Parallel Processing

O-Kaung Lim,Keum-Shik Hong,Hyuk-Soo Lee,Eun-Ho Choi 대한기계학회 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.7

The Genetic Algorithm (GA), an optimization technique based on the theory of natural selection, has proven to be a relatively robust means of searching for global optimum. It converges to the global optimum point without auxiliary information such as differentiation of function. In the case of a complex problem, the GA involves a large population number and requires a lot of computing time. To improve the process, this research used parallel processing with several personal computers. Parallel process technique is classified into two methods according to sub population's size and number. One is the fine~grained method (FGM) , and the other is the coarse-grained method (CGM). This study selected the CGM as a parallel process technique because the load is equally divided among several computers. The given design domain should be reduced according to the degree of feasibility, because mechanical system problems have constraints. The reduced domain is used as an initial design domain. It is consistent with the feasible domain and the infeasible domain around feasible domain boundary. This parallel process used the Message Passing Interface library.

Structural Topology Optimization for the Natural Frequency of a Designated Mode

O Kaung Lim,Jin Sik Lee 대한기계학회 2000 KSME International Journal Vol.14 No.3

Initial Design Domain Reset Method for Genetic Algorithm with Parallel Processing

Lim, O-Kaung,Hong, Keum-Shik,Lee, Hyuk-Soo,Park, Eun-Ho The Korean Society of Mechanical Engineers 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.7

The Genetic Algorithm (GA), an optimization technique based on the theory of natural selection, has proven to be a relatively robust means of searching for global optimum. It converges to the global optimum point without auxiliary information such as differentiation of function. In the case of a complex problem, the GA involves a large population number and requires a lot of computing time. To improve the process, this research used parallel processing with several personal computers. Parallel process technique is classified into two methods according to subpopulation's size and number. One is the fine-grained method (FGM), and the other is the coarse-grained method (CGM). This study selected the CGM as a parallel process technique because the load is equally divided among several computers. The given design domain should be reduced according to the degree of feasibility, because mechanical system problems have constraints. The reduced domain is used as an initial design domain. It is consistent with the feasible domain and the infeasible domain around feasible domain boundary. This parallel process used the Message Passing Interface library.

Structural Topology Optimization for the Natural Frequency of a Designated Mode

Lim, O-Kaung,Lee, Jin-Sik The Korean Society of Mechanical Engineers 2000 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.14 No.3

The homogenization method and the density function method are common approaches to evaluate the equivalent material properties for design cells composed of matter and void. In this research, using a new topology optimization method based on the homogenized material with a penalty factor and the chessboard prevention strategy, we obtain the optimal layout of a structure for the natural frequency of a designated mode. The volume fraction of nodes of each finite element is chosen as the design variable and a total material usage constraint is imposed. In this paper, the subspace method is used to evaluate the eigenvalue and its corresponding eigenvector of the structure for the designated mode and the recursive quadratic programming algorithm, PLBA algorithm, is used to solve the topology optimization problem.

프로젝트 비-부산대 창의융합형 설계교육

임오강(O-Kaung Lim),서영봉(Youngbong Seo),엄지인(Jiin Eom) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.6

연속충격을 고려한 발사대 반응특성 해석

임오강(Lim O-Kaung),유완석(Yoo Wan-Suk),최은호(Eun-Ho Ryu),류재봉(Jae-Bong Lee),이창훈(Lee Chang-Hoon),김상근(Kim Sang-Geun) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

A three dimensional multibody modeling of a launcher system was developed and dynamic characteristics of the system was carried out. All the components were modeled as rigid bodies, All the components of system, ie; chassis, turret, cage and suspension parts, are modeled as rigid. The force interaction between the ground and tire was modeled as a point contact model. The factors were selected as cause and effect diagram of the MINITAB. To see effect of the stiffness, damping, mass at the launcher system, several cases of suspension parameters were compared and optimal values were selected. The stiffness and the damping coefficient were selected as design variables to minimize the required time for the next fire. The dynamic simulation was carried out using the ADAMS, and the MINITAB was employed for data analysis.

위상최적화에서 응력량을 이용한 요소제거법의 개발

임오강(Lim O-Kaung),이진식(Lee Jin-Sik),김창식(Kim Chang-Sik) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.11

Topology optimization has been evolved into a very efficient conceptual design tool and has been utilized into design engineering processes in many industrial parts. In recent years, topology optimization has become the focus of structural optimization design and has been researched and widely applied both in academy and industry. Traditional topology optimization has been using homogenization method and optimality criteria method. Homogenization method provides relationship equation between structure which includes many holes and stiffness matrix in FEM. Optimality criteria method is used to update design variables while maintaining that volume fraction is uniform. Traditional topology optimization has advantage of good convergence but has disadvantage of too much convergency time and additive checkerboard prevention algorithm is needed. In one way to solve this problem, element remove method is presented. Then, it is applied to many examples. From the results, it is verified that the time of convergence is very improved and optimal designed results is obtained very similar to the results of traditional topology using 8 nodes per element.

人工 股關節의 응력 해석에 關한 小考

林五康,裴元炳 부산대학교 공과대학 1981 硏究報告 Vol.21 No.-

The stresses in the circular cross-section of three-layered cantilever model of Saint Venant bending were compared with those in a rectangular cross-section model of finite element stress analysis. In Saint Venant bending by a terminal force, a comparison was made of the stresses induced when poisson's ratios in each layer are equal and when they are different from on another. The stress obtained using the two dimensional model were 25∼30% greater than those calculated by the beam theory.

Psenichny의 線形化技法을 이용한 機械的 振動의 最適設計

林五康 부산대학교 공과대학 1986 硏究報告 Vol.32 No.-

Dynamic response optimization of mechanical system is implicit function of state variable and design variable so that it needs an efficient and robust algorithm. Pshenichny's linearization method for constrained optimization having active set strategy and global convergence is presented in this paper. Design sensitivity analysis techniques of point-wise state varible constraints are discussed. Optimum results for several problems are obtained and the method performs well on optimization of dynamic response.