• 제목/요약/키워드: Sequential Optimization

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Collaborative Optimization을 이용한 지구관측위성의 다분야 통합 최적 개념설계 (Multidisciplinary Design Optimization of Earth Observation Satellite Conceptual Design using Collaborative Optimization)

  • 김홍래;장영근
    • 한국항공우주학회지
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    • 제43권6호
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    • pp.568-583
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    • 2015
  • 본 논문에서는 다분야 통합 설계최적화(MDO : Multidisciplinary Design Optimization)를 적용한 지구관측위성의 개념설계 과정 및 결과를 기술하였다. 현재까지 구축된 지구관측 위성의 데이터베이스를 기반으로 주요 파라미터에 대한 개념설계식을 정립하였으며, 다분야 통합 최적설계 아키텍처 중 CO(Collaborative Optimization) 기반을 이용하여 지구관측 위성 시스템의 최적 개념설계를 수행할 수 있는 설계 도구를 개발하였다. 주어진 제약조건을 만족시키면서 위성의 총 질량을 최소화하는 것을 설계 목표로 설정하였으며, 최적화 알고리즘으로는 SQP(Sequential Quadratic Programming)를 이용하였다. 다분야 통합 최적설계를 적용한 개념설계 결과와 ASNARO-1 및 IKONOS-2 위성 규격의 비교를 통해 해당설계도구의 유용성을 검증하였다.

A New Hybrid Strategy for the Optimization of Xhemical Processing System

  • Cho, In-Ho;Yoon, En-Sup
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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    • pp.848-855
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    • 1989
  • By structural comparison of process optimization strategies based on Simultaneous Modular Approach, they can be classified into two groups : the Sequential Module Based Approach and the Two-Tier Approach. The Sequential Module Based Approach needs rigorous models and a set of accurate solutions are guranteed. However, it requires large amount of computation time. In the Two-Tier Approach composed of rigorous and simplified models, optimization calculation uses simplified models, therefore comparatively smaller amount of computation time is required but the obtained solutions may not be accurate. These optimization problems were somewhat improved by the alternate application of the two strategies. In this study, improved optimization strategy is suggested, in which Jacobian Matrix is modified to accomodate the strong points of above mentioned strategies. The results of case study show that this approach is superior to the other strategies.

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분산컴퓨팅 환경에서 공력 설계최적화의 효율성 연구 (A STUDY ON THE EFFICIENCY OF AERODYNAMIC DESIGN OPTIMIZATION IN DISTRIBUTED COMPUTING ENVIRONMENT)

  • 김양준;정현주;김태승;손창호;조창열
    • 한국전산유체공학회지
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    • 제11권2호
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    • pp.19-24
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    • 2006
  • A research to evaluate the efficiency of design optimization was carried out for aerodynamic design optimization problem in distributed computing environment. The aerodynamic analyses which take most of computational work during design optimization were divided into several jobs and allocated to associated PC clients through network. This is not a parallel process based on domain decomposition in a single analysis rather than a simultaneous distributed-analyses using network-distributed computers. GBOM(gradient-based optimization method), SAO(Sequential Approximate Optimization) and RSM(Response Surface Method) were implemented to perform design optimization of transonic airfoils and evaluate their efficiencies. dimensional minimization followed by direction search involved in the GBOM was found an obstacle against improving efficiency of the design process in the present distributed computing system. The SAO was found fairly suitable for the distributed computing environment even it has a handicap of local search. The RSM is apparently the most efficient algorithm in the present distributed computing environment, but additional trial and error works needed to enhance the reliability of the approximation model deteriorate its efficiency from the practical point of view.

Optimization of the Growth Rate of Probiotics in Fermented Milk Using Genetic Algorithms and Sequential Quadratic Programming Techniques

  • Chen, Ming-Ju;Chen, Kun-Nan;Lin, Chin-Wen
    • Asian-Australasian Journal of Animal Sciences
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    • 제16권6호
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    • pp.894-902
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    • 2003
  • Prebiotics (peptides, N-acetyglucoamine, fructo-oligosaccharides, isomalto-oligosaccharides and galactooligosaccharides) were added to skim milk in order to improve the growth rate of contained Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium longum and Bifidobacterium bifidum. The purpose of this research was to study the potential synergy between probiotics and prebiotics when present in milk, and to apply modern optimization techniques to obtain optimal design and performance for the growth rate of the probiotics using a response surface-modeling technique. To carry out response surface modeling, the regression method was performed on experimental results to build mathematical models. The models were then formulated as an objective function in an optimization problem that was consequently optimized using a genetic algorithm and sequential quadratic programming approach to obtain the maximum growth rate of the probiotics. The results showed that the quadratic models appeared to have the most accurate response surface fit. Both SQP and GA were able to identify the optimal combination of prebiotics to stimulate the growth of probiotics in milk. Comparing both methods, SQP appeared to be more efficient than GA at such a task.

대형 설계 시스템의 효율적 반응표면 근사화를 위한 점진적 이차 근사화 기법 (Progressive Quadratic Approximation Method for Effective Constructing the Second-Order Response Surface Models in the Large Scaled System Design)

  • 홍경진;김민수;최동훈
    • 대한기계학회논문집A
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    • 제24권12호
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    • pp.3040-3052
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    • 2000
  • For effective construction of second-order response surface models, an efficient quad ratic approximation method is proposed in the context of trust region model management strategy. In the proposed method, although only the linear and quadratic terms are uniquely determined using 2n+1 design points, the two-factor interaction terms are mathematically updated by normalized quasi-Newton formula. In order to show the numerical performance of the proposed approximation method, a sequential approximate optimizer is developed and solves a typical unconstrained optimization problem having 2, 6, 10, 15, 30 and 50 design variables, a gear reducer system design problem and two dynamic response optimization problems with multiple objectives, five objectives for one and two objectives for the other. Finally, their optimization results are compared with those of the CCD or the 50% over-determined D-optimal design combined with the same trust region sequential approximate optimizer. These comparisons show that the proposed method gives more efficient than others.

단순강판형 단면의 최적설계를 위한 효율적인 비선형계획기법 (Efficient NLP Techniques for the Optimum Design of Simple Steel Plate Girder Cross Section)

  • 김종옥
    • 한국농공학회지
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    • 제36권2호
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    • pp.111-122
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    • 1994
  • In this study, an algorithm which can be applied to the optimum design of simple steel plate girders was developed, and efficient optimization strategies for the solution of algorithm were found out. The optimum design algorithm consists of 3-levels of optimization. In the first and second levels of optimization, the absolute maximum bending moment and shearing force are extracted and in the third level of optimization, the optimum cross section of steel plate girder is determined. For the optimum design of cross section, the objective function is formulated as the total area of cross section and constraints are derived in consideration of the various stresses and the minimum dimension of flange and web based on the part of steel bridge in the Korea standard code of road bridge. Sequential unconstrained minimization technique using the exterior penalty function method(SUMT-EP), sequential linear programming(SLP) and sequential quadratic programming (SQP) are proved to be efficient and robust strategies for the optimum design of simple plate girder cross section. From the reliable point of view, SLP is the most efficient and robust strategy and SQP is the most efficient one from the viewpoint of converguency and computing time.

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Optimization of filling process in RTM using genetic algorithm

  • Kim, Byoung-Yoon;Nam, Gi-Joon;Ryu, Ho-Sok;Lee, Jae-Wook
    • Korea-Australia Rheology Journal
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    • 제12권1호
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    • pp.83-92
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    • 2000
  • In resin transfer molding (RTM) process, preplaced fiber mat is set up in a mold and thermoset resin is injected into the mold. An important interest in RTM process is to minimize cycle time without sacrificing part quality or increasing cost. In this study, the numerical simulation and optimization process in filling stage were conducted in order to determine the optimum gate locations. Control volume finite element method (CVFEM) was used in this numerical analysis with the coordinate transformation method to analyze the complex 3-dimensional structure. Experiments were performed to monitor the flow front to validate simulation results. The results of numerical simulation predicted well the experimental results with every single, simultaneous and sequential injection procedure. We performed the optimization analysis for the sequential injection procedure to minimize fill time. The complex geometry of an automobile bumper core was chosen. Genetic algorithm was used in order to determine the optimum gate locations with regard to 3-step sequential injection case. These results could provide the information of the optimum gate locations in each injection step and could predict fill time and flow front.

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Buckling optimization of unsymmetrically laminated plates under transverse loads

  • Hu, Hsuan-Teh;Chen, Zhong-Zhi
    • Structural Engineering and Mechanics
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    • 제7권1호
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    • pp.19-33
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    • 1999
  • The critical buckling loads of unsymmetrically laminated rectangular plates with a given material system and subjected to combined lateral and inplane loads are maximized with respect to fiber orientations by using a sequential linear programming method together with a simple move-limit strategy. Significant influence of plate aspect ratios, central circular cutouts, lateral loads and end conditions on the optimal fiber orientations and the associated optimal buckling loads of unsymmetrically laminated plates has been shown through this investigation.

Modified Fixed-Threshold SMO for 1-Slack Structural SVMs

  • Lee, Chang-Ki;Jang, Myung-Gil
    • ETRI Journal
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    • 제32권1호
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    • pp.120-128
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    • 2010
  • In this paper, we describe a modified fixed-threshold sequential minimal optimization (FSMO) for 1-slack structural support vector machine (SVM) problems. Because the modified FSMO uses the fact that the formulation of 1-slack structural SVMs has no bias, it breaks down the quadratic programming (QP) problems of 1-slack structural SVMs into a series of smallest QP problems, each involving only one variable. For various test sets, the modified FSMO is as accurate as existing structural SVM implementations (n-slack and 1-slack SVM-struct) but is faster on large data sets.

Efficient Mechanical System Optimization Using Two-Point Diagonal Quadratic Approximation in the Nonlinear Intervening Variable Space

  • Park, Dong-Hoon;Kim, Min-Soo;Kim, Jong-Rip;Jeon, Jae-Young
    • Journal of Mechanical Science and Technology
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    • 제15권9호
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    • pp.1257-1267
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    • 2001
  • For efficient mechanical system optimization, a new two-point approximation method is presented. Unlike the conventional two-point approximation methods such as TPEA, TANA, TANA-1, TANA-2 and TANA-3, this introduces the shifting level into each exponential intervening variable to avoid the lack of definition of the conventional exponential intervening variables due to zero-or negative-valued design variables. Then a new quadratic approximation whose Hessian matrix has only diagonal elements of different values is proposed in terms of these shifted exponential intervening variables. These diagonal elements are determined in a closed form that corrects the typical error in the approximate gradient of the TANA series due to the lack of definition of exponential type intervening variables and their incomplete second-order terms. Also, a correction coefficient is multiplied to the pre-determined quadratic term to match the value of approximate function with that of the previous point. Finally, in order to show the numerical performance of the proposed method, a sequential approximate optimizer is developed and applied to solve six typical design problems. These optimization results are compared with those of TANA-3. These comparisons show that the proposed method gives more efficient and reliable results than TANA-3.

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