• Title, Summary, Keyword: 이산최적화

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Optimum Design of Steel Structures Using Genetic Algorithms (유전자 알고리즘을 사용한 강구조물의 최적설계)

  • Kim, Bong Ik
    • Journal of Korean Society of Steel Construction
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    • v.24 no.6
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    • pp.701-710
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    • 2012
  • We present optimum design for truss and frame structures subject to constraints on stresses, displacement, and natural frequency. The optimum design procedure is used discrete and continuous design variables and Genetic Algorithms. Genetic Algorithms is used the method of Elitism and penalty parameters in order to improved fitness in the reproduction process, and optimum design is used steel(W-section) and pre-made discrete cross-section. Truss and frame structures optimization examples are used for 10-Bar truss, 25-Bar truss, 1-bay 2-story frame, 1-bay 7-story frame, and these examples are employed to demonstrate the availability and serviceability of Genetic Algorithms for solving optimum design of truss and frame.

Discrete Optimization of Unsymmetric Composite Laminates Using Linear Aproximation Method (선형 근사화방법을 이용한 비대칭 복합 적층평판의 이산최적화)

  • 이상근;구봉근;한상훈
    • Computational Structural Engineering
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    • v.10 no.2
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    • pp.255-263
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    • 1997
  • The optimum design of most structural systems used in practice requires considering design variables as discrete quantities. The present paper shows that the linear approximation method is very effective as a tool for the discrete optimum designs of unsymmetric composite laminates. The formulated design problem is subjected to a multiple in-plane loading condition due to shear and axial forces, bending and twisting moments, which is controlled by maximum strain criterion for each of the plys of a composite laminate. As an initial approach, the process of continuous variable optimization by FDM is required only once in operating discrete optimization. The nonlinear discrete optimization problem that has the discrete and continuous variables is transformed into the mixed integer programming problem by SLDP. In numerical examples, the discrete optimum solutions for the unsymmetric composite laminates consisted of six plys according to rotated stacking sequence were found, and then compared the results with the nonlinear branch and bound method to verify the efficiency of present method.

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Rule-based Hybrid Discretization of Discrete Particle Swarm Optimization for Optimal PV System Allocation (PV 시스템의 최적 배치 문제를 위한 이산 PSO에서의 규칙 기반 하이브리드 이산화)

  • Song, Hwa-Chang;Ko, Jae-Hwan;Choi, Byoung-Wook
    • Journal of Korean Institute of Intelligent Systems
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    • v.21 no.6
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    • pp.792-797
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    • 2011
  • This paper discusses the application of a hybrid discretiziation method for the discretization procedure that needs to be included in discrete particle swarm optimization (DPSO) for the problem of allocating PV (photovoltaic) systems onto distribution power systems. For this purpose, this paper proposes a rule-based expert system considering the objective function value and its optimizing speed as the input parameters and applied it to the PV allocation problem including discrete decision variables. For multi-level discretization, this paper adopts a hybrid method combined with a simple rounding and sigmoid funtion based 3-step and 5-step quantization methods, and the application of the rule based expert system proposing the adequate discretization method at each PSO iteration so that the DPSO with the hybrid discretization can provide better performance than the previous DPSO.

The Digital Controller Design using Multirate Discretization (멀티레이트 이산화를 이용한 디지털 제어기 설계)

  • 박종우;곽칠성
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.6 no.1
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    • pp.1-5
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    • 2002
  • A common way to design a digital control system is to design an analog controller first and discretize it for digital implemention. In this paper, optimal digital controller design is studied within the framework of sampled -data control theory. In particular, multirate discretization of analog controller is considered using an Η$_2$optimality criterion. Solutions are obtained via multirate H2 optimization with a causality constraint due to the multirate structure. In design example, the comparison of the proposed methods is made with the conventional discretization methods, and demonstrate the superiority of the multirate design method.

Discrete Optimization of Plane Frame Structures Using Genetic Algorithms (유전자 알고리즘을 이용한 뼈대구조물의 이산최적화)

  • 김봉익;권중현
    • Journal of Ocean Engineering and Technology
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    • v.16 no.4
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    • pp.25-31
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    • 2002
  • This paper is to find optimum design of plane framed structures with discrete variables. Global search algorithms for this problem are Genetic Algorithms(GAs), Simulated Annealing(SA) and Shuffled Complex Evolution(SCE), and hybrid methods (GAs-SA, GAs-SCE). GAs and SA are heuristic search algorithms and effective tools which is finding global solution for discrete optimization. In particular, GAs is known as the search method to find global optimum or near global optimum. In this paper, reinforced concrete plane frames with rectangular section and steel plane frames with W-sections are used for the design of discrete optimization. These structures are designed for stress constraints. The robust and effectiveness of Genetic Algorithms are demonstrated through several examples.

Design of Single Layer Radar Absorbing Structures(RAS) for Minimizing Radar Cross Section(RCS) Using Impedance Matching (임피던스정합을 이용한 레이더반사면적 최소화 단층형 전파흡수구조 설계)

  • Jang, Byung-Wook;Park, Jung-Sun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.2
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    • pp.118-124
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    • 2015
  • The design of radar absorbing structures(RAS) is a discrete optimization problem and is usually processed by stochastic optimization methods. The calculation of radar cross section(RCS) should be decreased to improve the efficiency of designing RAS. In this paper, an efficient method using impedance matching is studied to design RAS for minimizing RCS. Input impedance of the minimal RCS for the specified wave incident conditions is obtained by interlocking physical optics(PO) and optimizations. Complex permittivity and thickness of RAS are designed to satisfy the calculated input impedance by a discrete optimization. The results reveal that the studied method attains the same results as stochastic optimization which have to conduct numerous RCS analysis. The efficiency of designing RAS can be enhanced by reducing the calculation of RCS.

Multi-Objective Fuzzy Optimization of Structures (구조물에 대한 다목적퍼지최적화)

  • Park, Choon-Wook;Pyeon, Hae-Wan;Kang, Moon-Myung
    • Journal of Korean Society of Steel Construction
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    • v.12 no.5
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    • pp.503-513
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    • 2000
  • This study treats the criteria, considering the fuzziness occurred by optimization design. And we applied two weighting methods to show the relative importance of criteria. This study develops multi-objective optimization programs implementing plain stress analysis by FEM and discrete optimization design uniformaly. The developed program performs a sample design of 10-member steel truss. This study can carry over the multi-objective optimization based on total system fuzzy-genetic algorithms while performing the stress analysis and optimization design. Especially, when general optimization with unreliable constraints is cannot be solve this study can make optimization design closed to realistic with fuzzy theory.

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Integrated Structural Design Operation by Process Decomposition and Parallelization (프로세스 분할 병행에 의한 통합 구조설계 운용)

  • Hwang, Jin-Ha;Park, Jong-Hoi
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.21 no.1
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    • pp.113-124
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    • 2008
  • Distributed operation of overall structural design process, by which product optimization and process parallelization are simultaneously implemented, is presented in this paper. The database-interacted hybrid method, which selectively takes the accustomed procedure of the conventional method in the framework of the optimal design, is utilized here. The staged application of design constraints reduces the computational burden for large complex optimization problems. Two kinds of numeric and graphic processes are simultaneously implemented by concurrent engineering approach in the distributed environment of PC networks. The former is based on finite element optimization method and the latter is represented by AutoCAD using AutoLISP programming language. Numerical computation and database interaction on servers and graphic works on independent clients are communicated through message passing. The numerical experiments for some steel truss models show the validity and usability of the method. This study has sufficient adaptability and expandability, in that it is based on general methodologies and industry standard platforms.

Minimization of Sulfur Dioxide Gas Emission by Process Optimization of Sulfuric Acid Plants (공정최적화에 의한 황산공장의 이산화황가스 배출 최소화)

  • Cho Byoung-Hak;Song Kwang Ho;Kim In-Won
    • Journal of the Korean Institute of Gas
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    • v.3 no.2
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    • pp.70-76
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    • 1999
  • Because of the tight pollution control of $SO_2$ emission, sulfuric acid manufacturers have been interested in the operation with the highest possible conversion efficiency. In this work, the design criteria and operating conditions of the catalytic converter were investigated for maximum conversion efficiency and minimum $SO_2$ emission by parametric analysis and process optimization for the existing acid plants. The Double Converter/Double Absorber(DC/DA) process was investigated by varying $SO_2$ compositions of feed gas, pressures and temperatures of layers of the converter and the depth of the catalyst beds. In order to evaluate the process, a computer simulator for sulfuric acid plants has been developed. The results by process optimization could be used for the converter design and operating conditions with highest conversion efficiency.

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Development of Optimal Design Simulation Model for Least Cost Urban Sewer System Considering Risk (I) (위험도를 고려한 최소비용 도시우수관망 설계의 최적화 모형개발 (I): 모형의 개발과 시험유역의 적용)

  • Jang, Suk-Hwan;Park, Sang-Woo
    • Journal of Korea Water Resources Association
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    • v.38 no.12
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    • pp.1021-1028
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    • 2005
  • This study purpose to develop simulation model of optimal design condition of urban storm sewer system considering risk. Urban Storm Sewer Optimal Design Model(USSOD) can compute pipe capacity, pipe slope, crown elevation, excavation depth, risk and return cost in the condition of design discharge. Rational formula is adopted for design discharge and Manning's formula is used for pipe capacity. Discrete differential dynamic programming(DDDP) technique which is a kind of dynamic programming(DP) is used for optimization and first order second moment approximation method and uncertainty analysis is also for developing model. USSOD is applied to hypothetical drainage basin to test and verify, which resulted economical and efficient design in urban drainage sewer system.