[Article] 이산공간에서 순차적 알고리듬(SOA)을 이용한 전역최적화

조범상
한양대학교 기계설계학과, 박사과정

이정욱
대우 종합기계 특수사업부, 책임연구원

박경진
한양대학교 기계공학과, 교수

Key Words :
Discrete Design (이산설계), Sequential Algorithm(순차적 알고리듬), Genetic Algorithm(유전알고리듬), Orthogonal Arrays(직교배열표), Global Solution(전역해)

Abstract
In structural design, the design variables are frequently selected from certain discrete values. Various optimization algorithms have been developed for discrete design. It is well known that many function evaluations are needed in such optimization. Recently, sequential algorithm with orthogonal arrays (SOA), which is a search algorithm for a local minimum in a discrete space, has been developed. It considerably reduces the number of function evaluations. However, it only finds a local minimum and the final solution depends on the initial values of the design variables. A new algorithm is proposed to adopt a genetic algorithm (GA) in SOA. The GA can find a solution in a global sense. The solution from the GA is used as the initial design of SOA. A sequential usage of the GA and SOA is carried out in an iterative manner until the convergence criteria are satisfied. The performance of the algorithm is evaluated by various examples.

대한기계학회논문집 A권, 제29권 제10호

[Article] Global Optimization Using a Sequential Algorithm with Orthogonal Arrays and a Genetic Algorithm in a Discrete Space

Bum-Sang Cho
Ph.D. student,
Department of Mechanical Design and Production Engineering,
Hanyang University,17 Haengdang-dong, Sungdong-gu, Seoul 133-791, South Korea

Jeong-Wook Yi
Senior engineer,
Defense Products Division, Doosan Infracore Co., Ltd.
Institute of Advanced Engineering, Goan-ri, Packam-myun, Yongin, Gyeonggi-do 449-860, South Korea

Gyung-Jin Park
Corresponding author, Professor,
Division of Mechanical and Information Management, College of Engineering Science, Hanyang University, 1271 Sa-1-dong, Sangnok-gu, Ansan, Gyeonggi-do 426-791, South Korea

Key Words :
Discrete design, Sequential algorithm using orthogonal arrays, Genetic algorithm, Orthogonal arrays, Global solution

Abstract
In structural design, the design variables are frequently selected from certain discrete values. Various optimization algorithms have been developed for discrete design. It is well known that many function evaluations are needed in such an optimization. Recently, the sequential algorithm with orthogonal arrays (SOA), which is a search algorithm for a local minimum in a discrete space, has been developed. It considerably reduces the number of function evaluations. However, it only finds a local minimum and the final solution depends on the initial values of the design variables. A new algorithm is proposed to adopt the genetic algorithm (GA) in the SOA. The GA can find a globally excellent solution. The solution from the GA is used as the initial design of the SOA. The sequential usage of the GA and the SOA is carried out in an iterative manner until the convergence criteria are satisfied. The performance of the algorithm is evaluated by various examples.

[PROJ] Deflection of grinding table [1]

LCD panel에 대한 광학 테스트 및 연마를 위한 연마테이블(grinding talbe)의 처짐에 관한 연구

LCD panel의 크기가 커짐에 따라 연마테이블의 크기도 비례하여 커지게 된다. 57"이상의 연마테이블의 경우 장축의 처짐이 40E-6(m)이하여야 하지만 기존의 연마테이블은 처짐량에 대한 제한조건을 만족할 경우 무게에 대한 제한조건이 만족되지 않는 결과를 가져오고 있다. 따라서 이에 대한 구조해석 및 최적설계가 필요하다.

기존의 설계에 대한 치수 및 형상 최적설계를 시행할 것이며, 그와 별개로 새로운 형상의 연마테이블을 유추해내기 위해 위상최적설계를 실시할 계획이다.

계획된 일정은 한달 정도이며 되도록 NX Nastran과 FEMAP만을 이용하여 Pre/Post 및 Analysis, Optimization을 수행할 것이다.