• Korean Chemical Engineering Research
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• 제52권5호
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• pp.564-573
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• 2014

이 연구는 벤젠과 프로필렌의 기상반응을 통해 쿠멘을 생산하는 쿠멘 생산 공정의 경제성 최적화에 대한 것이다. 최적화의 목적함수는 제품 판매 이득에서 자본비용, 유틸리티 비용, 원료 비용을 뺀 연간 조업이득이고, 설계변수는 6개이다. 설계변수의 변화에 따른 조업이득의 계산을 위해 Unisim Design과 Matlab을 연동하였다. 최적화는 3단계로 수행되었다. 설계변수를 샘플링한 후 조업이득 데이터를 얻고, 이 데이터로부터 설계변수와 조업이득의 관계를 추정 모델로 표현하고, 이 모델을 이용하여 최적화하였다. 추정모델로는 반응표면법에서 사용되는 2차 회귀 다항식과 비선형 모델인 support vector regression을 비교하였다. 설계변수의 샘플링 방법으로는 중심합성계획과 Hammersley 순차 추출법을 비교하였다. 각각 얻어진 모델을 이용한 최적화 결과, 추정방법으로는 SVR이, 샘플링 방법은 Hammersley 순차추출법이 더 정확하였다. 최적화된 조업이득은 연간 17.96 MM$로, 기준 조건에서의 연간 16.04 MM$에 비해 12% 증가하였다.

• 한국기계가공학회지
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• 제15권3호
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• pp.8-14
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• 2016

Medical bed head consoles (BHC) are generally used to increase the efficiency of medical equipment and speed the medical treatment response time. The BHC design has been consistently improved including a movable shelf unit that is embedded to mount stably medical instruments on the lower part of the main console. The cost of a BHC can be reduced through design optimization to limit the overall weight. However, as the size of a head console might decrease due to design optimization, the BHC deflection could be increased. In this study, multi-objective optimal design was adopted to consider this BHC design problem. In order to reduce the cost of optimization planning, an approximate model was applied for the design optimization. In the context of approximate optimization, we used the response surface method and non-dominant sorting genetic algorithm developed from various fields. Multi-objective optimal solutions were also compared with a single objective optimal design.

• 대한기계학회논문집A
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• 제39권8호
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• pp.823-830
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• 2015

구조최적설계는 구조물의 성능 개선을 추구하며, 최근에는 구조최적설계는 항공기와 같이 복잡하고 대형인 구조물의 설계에 적용되고 있다. 해석의 정확도를 높이기 위해 유한요소의 수가 증가하는 추세이나 이는 설계 비용의 증가로 이어진다. 이에 부분구조합성법으로써 구분모드합성법이 해석시간 단축을 위해 종종 사용되어 왔다. 본 연구에서는 구조물의 동적특성을 고려하고 해석의 정확도는 유지하면서, 설계에 소요되는 시간과 비용을 줄일 수 있는 설계방법을 제안한다. 제안한 방법은 등가정하중을 이용한 동적응답 최적설계에, 부분구조합성법을 적용하여 설계영역만을 고려한 구조최적설계를 수행하는 것이다. 제안한 방법의 유용성 검증을 위하여 선형 및 비선형 동적응답 최적설계의 예제를 풀이하고, 그 결과에 대해 토의한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.253-258
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• 2000

Recently, the area of design optimization, especially structural optimization, has been and to be a continuous active area of research. And the design optimizations of port facilities have been achieved by many other civil engineers. But the design optimization of port facilities were limited to the design optimization of the breasting dolphin. This paper invested the design optimization of mooring pier and the foundations of mooring pier was suggested considering the convenience of repair and reinforcement work. The mooring pier devised with prestressed precast concrete panel and rigid frame welded wide flange beam to steel pipe pile. To accomplish the design optimization of mooring pier, the Augmented Lagrangian Multiplier Method(ALM) of ADS(Garret N. Vanderplaats) optimization routine, BFGS method as optimizer and Golden Section Method as one dimensional search were utilized. As a result, thirty percent of material cost for construction was reduced by design optimization. The tensile stress of concrete panel and bottom flage was critical constraints under service load. So, using high strength concrete and steel will be economical. And lots of initial values must be invested to accomplish the design optimization in design procedures.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1996년도 가을 학술발표회 논문집
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• pp.304-312
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• 1996

Concepts, methods and tools for interactive CAD-based concurrent engineering design optimization of mechanical/structural systems and components which are critical in terms of cost development time, functionality and quality, are presented. The emphasis is on implementation of methods and capabilities for the optimization of composite structural system, and the integration of design process and manufacturing process of composite structures into standard CAD-based concurrent engineering environment The optimization of composite fuselage structures are performed under concurrent engineering environment for the example.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권2호
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• pp.84-89
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• 2003

The finite element method (FEM) is typically used in the process of motor design. However, the FEM requires computation time, Therefore, decreasing the number of FEM simulations may also decrease the simulation cost. Several optimal design methods overcoming this problem have been recently studied. This paper investigates the optimal design of the magnet pole of a BLDC motor through reducing simulation cost. The optimization minimizes the magnet volume and limits the average and cogging torques to certain values. In this paper, the response surface methodology and Taguchi's table for reducing the number of FEM simulations are used to approximate two constraints. The optimization result shows that the presented strategy is satisfactorily performed.

• Structural Engineering and Mechanics
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• 제45권2호
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• pp.211-232
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• 2013

In this study a multi-objective optimization problem is solved. The objectives used here include simultaneous minimum construction cost in term of sections weight, minimum structural damage using a damage index, and minimum non-structural damage in term of inter-story drift under the applied ground motions. A high-speed and low-error neural network is trained and employed in the process of optimization to estimate the results of non-linear time history analysis. This approach can be utilized for all steel or concrete frame structures. In this study, the optimal design of a planar eccentric braced steel frame is performed with great detail, using the presented multi-objective algorithm with a discrete population and then a moment resisting frame is solved as a supplementary example.

• 상하수도학회지
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• 제27권4호
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• pp.413-428
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• 2013

In this study, Ant Colony Algorithm(ACO) was used for optimal model. ACO which are metaheuristic algorithm for combinatorial optimization problem are inspired by the fact that ants are able to find the shortest route between their nest and food source. For applying the model to water distribution systems, pipes, tanks(reservoirs), pump construction and pump operation cost were considered as object function and pressure at each node and reservoir level were considered as constraints. Modified model from Ostfeld and Tubaltzev(2008) was verified by applying 2-Looped, Hanoi and Ostfeld's networks. And sensitivity analysis about ant number, number of ants in a best group and pheromone decrease rate was accomplished. After the verification, it was applied to real water network from S water treatment plant. As a result of the analysis, in the Two-looped network, the best design cost was found to $419,000 and in the Hanoi network, the best design cost was calculated to $6,164,384, and in the Ostfeld's network, the best design cost was found to $3,525,096. These are almost equal or better result compared with previous researches. Last, the cost of optimal design for real network, was found for 66 billion dollar that is 8.8 % lower than before. In addition, optimal diameter for aged pipes was found in this study and the 5 of 8 aged pipes were changed the diameter. Through this result, pipe construction cost reduction was found to 11 percent lower than before. And to conclusion, The least cost design model on water distribution system was developed and verified successfully in this study and it will be very useful not only optimal pipe change plan but optimization plan for whole water distribution system.

• Computers and Concrete
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• 제18권5호
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• pp.983-998
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• 2016

Structural optimization is one of the most important topics in structural engineering and has a wide range of applicability. Therefore, the main objective of the present study is to apply the Lagrange Multiplier Method (LMM) for minimum cost design of singly and doubly reinforced rectangular concrete beams. Concrete and steel material costs are used as objective cost function to be minimized in this study, and ultimate flexural strength of the beam is considered to be as the main constraint. The ultimate limit state method with partial material strength factors and equivalent concrete stress block is used to derive general relations for flexural strength of RC beam and empirical coefficients are taken from topic 9 of the Iranian National Building Regulation (INBR9). Optimum designs are obtained by using the LMM and are presented in closed form solutions. Graphical representation of solutions are presented and it is shown that proposed design curves can be used for minimum cost design of the beams without prior knowledge of optimization and without the need for iterative trials. The applicability of the proposed relations and curves are demonstrated through two real life examples of SRB and DRB design situations and it is shown that the minimum cost design is actually reached using proposed method.

• Tribology and Lubricants
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• 제39권3호
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• pp.94-101
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• 2023

Automotive wheel bearings are a critical component of vehicles that support their weight and facilitate rotation. Life and stiffness are significant performance characteristics of wheel bearings. Designing wheel bearings involves finding optimal design variables that satisfy both performances. CO₂ emission reduction and fuel efficiency regulations attribute to the recent increase in design requirements for lightweight and compact automotive parts while maintaining performance. However, achieving a design that maintains performance while reducing weight poses challenges, as performance and weight are generally inversely proportional. In this study, we perform design optimization of automotive wheel bearings considering life and stiffness. We develop a program that calculates the basic rated life and modified rated life based on international standards for evaluating the life of wheel bearings. We develop a regression equation using regression analysis to address the time-consuming stiffness analysis during repetitive analysis. We perform ANOVA and main effect analyses to understand the statistical characteristics of the developed regression equation. Furthermore, we verify its reliability by comparing the predicted and test results. We perform design optimization using the developed life prediction program, stiffness regression equation and weight regression equation. We select bearing specifications and geometry as design variables, weight as the cost function, and life and stiffness as constraints. Through design optimization, we investigate the influence of design variables on the cost function and constraints by comparing the initial and optimal design values.