• 한국정밀공학회지
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• 제21권9호
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• pp.149-157
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• 2004

This paper presents a new method for hi-objective optimization. Ordinary weighted sum method is easy to implement, but it has two significant drawbacks: (1) the solution distribution by the weighted sum method is not uniform, and (2) the method cannot determine any solutions that reside in non-convex regions of a Pareto front. The proposed adaptive weighted sum method does not solve a multiobjective optimization in a predetermined way, but it focuses on the regions that need more refinement by imposing additional inequality constraints. It is demonstrated that the adaptive weighted sum method produces uniformly distributed solutions and finds solutions on non-convex regions. Two numerical examples and a simple structural problem are presented to verify the performance of the proposed method.

• Structural Engineering and Mechanics
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• 제76권6호
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• pp.781-797
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• 2020

In recent years, there is an increasing interest to optimize the fuzzy logic controller with different methods. This paper focuses on the optimization of a fuzzy logic controller applied to a seismically excited nonlinear building. In most cases, this problem is formulated based on the linear behavior of the structure, however in this paper, four sets of objective functions are considered with respect to the nonlinear responses of the structure as the peak interstory drift ratio, the peak level acceleration, the ductility factor and the maximum control force. The Improved Charged System Search is used to optimize the membership functions and the rule base of the fuzzy controller. The obtained results of the optimized and the non-optimized fuzzy controllers are compared to the uncontrolled responses of the structure. Also, the performance of the utilized method is compared with various classical and advanced optimization algorithms.

• 한국추진공학회지
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• 제20권6호
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• pp.29-37
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• 2016

본 논문에서는 유한요소해석을 이용하여 복합재 연소관의 금속 보스에 대한 형상 최적설계기법을 제안하였다. 복합재 연소관의 구조 안전성을 위해 연소관 내압에 의한 돔 부위의 섬유응력과 보스 체결 볼트의 응력을 제한하였고, 경량화를 위해 보스의 무게를 목적함수로 설정하였다. 또한 반응표면법을 이용하여 특성치에 대한 반응표면모델을 구축하였다. 그리고 분산분석을 이용해 각 특성치에 대한 설계변수의 유의성을 평가하고 회귀분석을 통해 구축된 모델의 적합성을 검증하였다. 최적화를 위해 순차이차계획법 알고리즘을 이용하였고, 도출된 최적형상에 대한 구조해석을 수행함으로써 제안한 기법의 효용성을 검증하였다.

• 한국전산구조공학회논문집
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• 제21권5호
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• pp.413-419
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• 2008

확정론적 최적설계에서는 설계변수의 변동이나 불확실성 등을 최적화 과정에서 고려하지 않는다. 신뢰성 최적설계는 설계변수의 임의성을 체계적인 확률 및 통계이론을 적용하여 생산품의 안정성을 보다 정밀하고 합리적으로 다룬다. 본 논문에서 설계변수를 확률변수로 취급하여 실제 제작시의 제작오차를 고려한 표준편차를 주었으며, 설계변수의 평균에 대한 표준편차를 기존의 고정된 값을 사용하지 앉고 평균과 표준편차의 관계가 오목함수로 나타나도록 하였다 즉, 설계변수의 평균이 달라짐에 따라 표준편차도 변동계수만큼 변하도록 하였다. 신뢰성해석은 불변 2차 모멘트 방법을 이용하고 신뢰성을 구하는 방법은 신뢰도 지수 접근방법의 개선된 일계 2차 모멘트 방법을 이용하여 신뢰성을 구하였다. 두 가지 예제를 통해 확정론적 최적설계, 신뢰성 최적설계와 표준편차의 변동을 고려한 신뢰성 최적설계의 값을 비교하였다.

• Earthquakes and Structures
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• 제12권3호
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• pp.309-319
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• 2017

A new method is suggested for the retrofitting of torsionally sensitive buildings. The main objective is to eliminate the torsional component from the first two natural modes of the structure by properly modifying its stiffness distribution via selective strengthening of its vertical elements. Due to the multi-parameter nature of this problem, state-of-art optimization schemes together with an ad-hoc software implementation were used for quantifying the required stiffness increase, determine the required retrofitting scheme and finally design and analyze the required composite sections for structural rehabilitation. The performance of the suggested method and its positive impact on the earthquake response of such structures is demonstrated through benchmark examples and applications on actual torsionally sensitive buildings.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.391-393
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• 2004

For performance and stability of a synchronized system, we need an efficient Clock Tree Synthesis(CTS) methodology to design clock distribution networks. In a system-on-a-chip(SOC) design environment, CTS effectively distributes clock signals from clock sources to synchronized points on layout design. In this paper, we suggest the pre-layout analysis of the clock network including gated clock, multiple clock, and test mode CTS optimization. This analysis can help to avoid design failure with potential CTS problems from logic designers and supply layout constraints so as to get an optimal clock distribution network. Our new design flow including pre-layout CTS analysis and structural violation checking also contributes to reduce design time significantly.

• Steel and Composite Structures
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• 제1권4호
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• pp.377-392
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• 2001

The response of multi-story building structures to lateral loads, mainly due to earthquake and wind, is investigated for preliminary design purposes. Emphasis is placed on structural systems consisting of rigid and braced steel frames. An attempt to gain a qualitative understanding of the influence of bending and shear stiffness distribution on the deformations of such structures is made. This is achieved by modeling the structure with a stiffness equivalent Timoshenko beam. It is observed that the conventional stiffness distribution, dictated by strength constraints, may not be the best to satisfy deflection criteria. This is particularly the case for slender structural systems with prevailing bending deformations, such as flexible braced frames. This suggests that a new approach to the design of such frames may be appropriate when serviceability governs. A pertinent strategy for preliminary design purposes is proposed.

• 한국기계기술학회지
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• 제20권6호
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• pp.830-835
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• 2018

The tubular link chain conveyor works under very extreme conditions such as high tensile load, friction, and dangerous operating environments. In this study, we propose an optimal design plan for reducing cost and improving performance through weight reduction of tubular link chain conveyors for sludge transport. For light weight of tubular link chain conveyor, the optimization software using SHERPA algorithms, HEEDS was used in conjunction with ANSYS Mechanical V14.5, which is widely used in structural analysis, to achieve optimal tubular link chain. Through the optimization process, 19% light weight was achieved.

• Structural Engineering and Mechanics
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• 제86권2호
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• pp.197-209
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• 2023

In the case of designing control devices in a building, reliance on experimental formulation or engineering concepts without using optimization algorithms leads to non-optimal solutions or design parameters, which makes the use of control devices costly and unreasonable. The optimization algorithms are capable of identifying the required number of parameters for a specific design problem, however, this process is difficult and inefficient in dealing with some specific optimal design processes. This paper aims to introduce an upgraded version of the salp swarm algorithm to handle some engineering design. The performance of the new upgraded algorithm is tested using some benchmark test functions as well as a six-story benchmark building equipped with semi-active MR dampers. The simulation results show that the proposed algorithm can be successfully applied to get an optimal design of the MR dampers in the building.

• 대한기계학회논문집A
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• 제35권5호
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• pp.575-582
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• 2011

클리닝 블레이드는 레이저 프린터 토너 카트리지에 장착된 감광드럼 표면의 잔류 토너를 제거하는 우레탄 재질의 고무부품이다. 기존에는 고무 블레이드의 클리닝 성능과 수명에 대한 다양한 연구들이 수행되었으나, 본 연구에서는 클리닝 성능과 부품간의 간섭에 대한 구속조건들을 모두 만족하면서 클리닝 블레이드에 발생하는 최대응력을 최소화 하는 클리닝 블레이드의 형상최적설계를 수행하였다. 상용 PIDO 툴인 PIAnO 를 이용하여 클리닝 블레이드의 구조해석절차를 통합하고 자동화하였으며, 최적설계를 위해 PIAnO 에서 제공하는 실험계획법과 근사화기법, 최적화 알고리즘을 사용하였다. 최적설계 결과, 초기 모델 대비 최대응력을 32.6% 감소 시킬 수 있는 최적의 설계안을 도출하였으며, 이를 통해 본 연구에서 수행한 최적설계 방법의 유효성을 확인할 수 있었다.