• Structural Engineering and Mechanics
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• 제54권6호
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• pp.1097-1109
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• 2015

A novel optimization approach for reinforced concrete (RC) biaxially loaded columns is proposed. Since there are several design constraints and influences, a new computation methodology using iterative analyses for several stages is proposed. In the proposed methodology random iterations are combined with music inspired metaheuristic algorithm called harmony search by modifying the classical rules of the employed algorithm for the problem. Differently from previous approaches, a detailed and practical optimum reinforcement design is done in addition to optimization of dimensions. The main objective of the optimization is the total material cost and the optimization is important for RC members since steel and concrete are very different materials in cost and properties. The methodology was applied for 12 cases of flexural moment combinations. Also, the optimum results are found by using 3 different axial forces for all cases. According to the results, the proposed method is effective to find a detailed optimum result with different number of bars and various sizes which can be only found by 2000 trial of an engineer. Thus, the cost economy is provided by using optimum bars with different sizes.

• 대한산업공학회지
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• 제8권1호
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• pp.3-12
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• 1982

Three types of repair-ordering polices for the production facility with r-out-of-n configuration are considered. Policies are characterized by states of the system and two types of lead times ; regular lead time and expedited lead time. Optimum repair-ordering policy is determined by minimizing the cost rate for the system. Optimum policy consists of the type of policies and repair-ordering time. Variations of the optimum policies are observed with respect to variations of lead times and associated ordering costs and downtime cost, respectively.

• 소음진동
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• 제9권4호
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• pp.738-746
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• 1999

The performance of muffler can be improved for a frequency range of interest by moving inlet and outlet locations. And optimal location of inlet and outlet can be determined to improve the acoustic performance. The optimum design using FEM, however, may take a very long time and be very hard to take inlet and outlet locations as design variables. In this paper, the acoustic performance of reactive type single expansion chamber muffler is predicted using higher order mode theory. The sensitivity analysis of transmission loss with respect to the location of inlet and outlet is suggested. And the acoustic power transmission coefficient for a frequency of interest is used as cost function. Optimum location of inlet and outlet is determined to minimize cost function by using SUMT algorithm.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1992년도 봄 학술발표회 논문집
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• pp.134-139
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• 1992

This study introduces simple derivation of optimum load factors based on both cornell's MFOSM (Mean First Order End Moment) methods and Lind - Hasofers AFOSM (Advanced First Order 2nd Moment) methods and demonstrates the relationship between the optimum reliability, the load factors, the probability distributions selected to model the load, and a measure of relative failure cost. Although some of the cost parameters cannot be evaluated accurately and the upper tail characteristics of the distributions of the random loads remain uncertainty, this optimum reliability formulation provides insight on which Parameters are most significant in selecting appropriate load criteria for structure design.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.315-320
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• 2003

Selecting a railroad line requires the comparative evaluation of various elements. As a systematic approach to this selection it will be necessary to apply the VE study and the LCC analysis. This study proposes a methodology for selecting the optimum line of the ralroad using VE-LCC analysis. The VE study is performed by following four steps : Information analysis, Function analysis, Alternative evaluation, and Optimum plan selection. The economics evaluation in VE study is using LCC analysis and Sensitivity analysis. Cost items in LCC analysis are classified into bridge, tunnel, rail, and earthwork. We could select the optimum alte-rnatives considering not only cost elements hut also various evaluation element in VE-LCC analysis. The synthetic evaluation process of relative value composition and weighted matrix evaluation

• Structural Engineering and Mechanics
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• 제88권3호
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• pp.273-285
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• 2023

This study examines how the interaction between soil and a wind turbine's supporting system affects the optimal design. The supporting system resting on an elastic soil foundation consists of a steel conical tower and a concrete circular raft foundation, and it is subjected to wind loads. The material cost of the supporting system is aimed to be minimized employing various metaheuristic optimization algorithms including teaching-learning based optimization (TLBO). To include the influence of the soil in the optimization process, modified Vlasov and Gazetas elastic soil models are integrated into the optimization algorithms using the application programing interface (API) feature of the structural analysis program providing two-way data flow. As far as the optimal designs are considered, the best minimum cost design is achieved for the TLBO algorithm, and the modified Vlasov model makes the design economical compared with the simple Gazetas and infinitely rigid soil models. Especially, the optimum design dimensions of the raft foundation extremely reduce when the Vlasov realistic soil reactions are included in the optimum analysis. Additionally, as the designated design wind speed is decreased, the beneficial impact of soil interaction on the optimum material cost diminishes.

• Journal of Biosystems Engineering
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• 제28권4호
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• pp.315-324
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• 2003

If an optimum design technique is applied in the design of packaging container for bulk-type products, merits on the side of not only economic and compression performance but distribution efficiency are expected. Accordingly, minimum board area (mRBA), compression strength (CS) and compression strength per unit area (mCSPA) are important design parameters in optimum design of packaging container for bulk-type products. In this study, mathematical models for mRBA, CS and mCSPA of container as algorithm for optimum design program were developed. In order to develop these models, compression test by various dimensions of container and response surface analysis for mRBA, CS, and mCSPA of container were carried out. In the developed models, volume, W/L ratio and depth of container were principal independent variables. On the found of these models, optimum design program having faculties of outward and inward optimum design and information design was developed. Though the packaging specifications are same, required board area, board combination and cost of the corrugated board required container manufacture were greatly different by boundary conditions in outward design. Moreover, about 6.3∼10.1% in weight of container was lighter, and about 13.2∼25.6% in cost of container was reduced when the program was applied for 2 kinds of bulk-type products.

• 한국컴퓨터정보학회논문지
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• 제16권5호
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• pp.101-107
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• 2011

본 논문에서는 적응 배열 안테나 시스템에서 간섭 및 재밍 신호를 제거하기 위해서 최적 가중 벡터를 연구하였다. 최적 가중 벡터는 선형 제한 조건에서 최소 분산 알고리즘과 비용함수를 적용시켜 구하였고, 목표물의 신호를 정확히 추정하였다. 적응 배열 안테나 시스템은 간섭 및 재머전력을 감소시키고 신호대 잡음비를 향상시키는 시스템이다. 적응 배열 안테나 시스템은 각 안테나 배열 소자의 출력이 탭(Tap)을 거쳐 지연되고 각 탭에 복소 가중치가 곱해져서 최종적으로 하나의 복합신호를 만든다. 최적의 가중치를 구하기 위해서 본 논문에서는 입력 공분산 행렬의 최적 가중벡터를 이용하였다. 본 논문에서 제안된 알고리즘으로 모의 실험한 결과 분해능은 $3^{\circ}$이하로 향상되었으며 부엽은 약 10 dB 감소하였음을 입증하였다.

• 산업경영시스템학회지
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• 제34권3호
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• pp.49-56
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• 2011

Estimating optimum hardware capacity of an e-learning system is very important process to grasp reasonable size of designing technique architecture and budget during step of ISP(information strategic planning) and development. It hugely influences cost and quality of the whole project. While investment on information system hardware has been continuously increased, there was no certified hardware capacity estimating method in e-learning system development. A guideline for hardware sizing of information systems was established by Telecommunication Technology Association in 2008. However, the guideline is not appropriate for estimating optimum hardware capacity of an e-learning system because it was designed to provide general standards for estimating hardware capacity of various types of projects. The purpose of this paper is to provide a methodology for estimating optimum hardware capacity in e-learning system development. To develop the methodology, this study, first of all, analyzes two e-learning development projects, in which the guideline was applied to estimate optimum hardware capacity. Then, this study finds out several key factors influencing on hardware capacity. Finally, this study suggests a methodology for estimating optimum hardware capacity of an e-learning system, in which weights for the factors are determined through AHP analysis.

• 한국강구조학회 논문집
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• 제17권2호통권75호
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• pp.227-241
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• 2005

본 논문에서는 생애주기동안 발생하는 부식이나 일평균교통량 및 중차량의 통행량와 같은 사용환경에 의존하는 강교의 생애신뢰성에 기초한 생애주기비용(Life-Cycle Cost: 이하 LCC) 최적설계 방법론을 제안하였다. 강교 최적설계를 위한 LCC는 초기비용, 생애주기 기대유지관리비용, 생애주기 기대직접복구비용과 인적 혹은 물적손실비용, 도로이용자비용, 그리고 사회-경제 손실비용을 포함하는 간접복구비용을 현재가치의 합으로 정식화하였다. 이러한 LCC비용항목 중에서 생애주기 복구비용의 산정을 위해서는 하중과 저항이력에 의존하는 누적손확률로부터 산정되는 연파손확률이 고려되어야한다. 이를 위해 본 논문에서는 Nowak의 활하중 모델(1993)과 부식개시, 부식률, 그리고 재도장영향을 고려한 수정된 부식모델을 제안하였다. 이와같이 본 연구에서 제안된 LCC 최적설계 방법론은 3 경간연속(40m+50m+40m= 130m)의 실제 강박스거더교에 적용되었고, 사용환경에 대한 LCC의 효율성에 대해 비교 고찰하였다. 적용예를 통해 부식환경, 일평균교통량, 그리고 중차량의 통행량는 강교 LCC최적설계에 매우 중요한 영향을 미칠 수 있음을 알 수 있었으며, 이러한 교량의 사용환경인자들은 경우에 따라 LCC 최적설계에 대한 주요 변수로 고려되어야 할 것으로 판단된다.