• Steel and Composite Structures
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• 제25권4호
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• pp.403-413
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• 2017

The fabric braided braking hose that delivers the driver's braking force to brake cylinder undergoes the large deformation cyclic motion according to the steering and bump/rebound motions of vehicle. The cyclic large deformation of braking hose may give rise to two critical problems: the interference with other adjacent vehicle parts and the micro cracking stemming from the fatigue damage accumulation. Hence, both the hose deformation and the fatigue damage become the critical issue in the design of braking hose. In this context, this paper introduces a multi-objective optimization method for minimizing the both quantities. The total length of hose and the helix angles of fabric braided composite layers are chosen for the design variables, and the maximum hose deformation and the critical fatigue life cycle are defined by the individual single objective functions. The trade-off between two single objective functions is made by introducing the weighting factors. The proposed optimization method is validated and the improvement of initial hose design is examined through the benchmark simulation. Furthermore, the dependence of optimum solutions on the weighting factors is also investigated.

• Steel and Composite Structures
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• 제33권6호
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• pp.767-776
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• 2019

In this article, a simple and robust multi-objective assessment method to control design angles and node positions connected among steel outrigger truss members is proposed to approve both structural safety and economical cost. For given outrigger member layouts, the present method utilizes general-purpose prototypes of outrigger members, having resistance to withstand lateral load effects directly applied to tall buildings, which conform to variable connecting node and design space deposition. Outrigger layouts are set into several initial design conditions of height to width of an arbitrary given design space, i.e., variable design space. And then they are assessed in terms of a proposed multi-objective function optimizing both minimal total displacement and material quantity subjected to design impact factor indicating the importance of objectives. To evaluate the proposed multi-objective function, an analysis model uses a modified Maxwell-Mohr method, and an optimization model is defined by a ground structure assuming arbitrary discrete straight members. It provides a new robust assessment model from a local design point of view, as it may produce specific optimal prototypes of outrigger layouts corresponding to arbitrary height and width ratio of design space. Numerical examples verify the validity and robustness of the present assessment method for controlling prototypes of outrigger truss members considering a multi-objective optimization achieving structural safety and material cost.

• Steel and Composite Structures
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• 제19권2호
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• pp.263-275
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• 2015

This study presents conceptual information of newly optimized shapes and connectivity of the so-called outrigger truss system for modern tall buildings that resists lateral loads induced by wind and earthquake forces. In practice, the outrigger truss consists of triangular or Vierendeel types to stiffen tall buildings, and the decision of outrigger design has been qualitatively achieved by only engineers' experience and intuition, including information of structural behaviors, although outrigger shapes and the member's connectivity absolutely affect building stiffness, the input of material, construction ability and so on. Therefore the design of outrigger trusses needs to be measured and determined according to scientific proofs like reliable optimal design tools. In this study, at first the shape and connectivity of an outrigger truss system are visually evaluated by using a conceptual design tool of the classical topology optimization method, and then are quantitatively investigated with respect to a structural safety as stiffness, an economical aspect as material quantity, and construction characteristics as the number of member connection. Numerical applications are studied to verify the effectiveness of the proposed design process to generate a new shape and connectivity of the outrigger for both static and dynamic responses.

• 대한기계학회논문집A
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• 제38권3호
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• pp.309-314
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• 2014

기계나 토목 구조물의 형상은 일반적으로 전통적인 방법들을 이용하여 얻었다. 예를 들면 전력송전탑이나 해상풍력 하부구조물 이외의 다른 구조물들도 조직적으로 만든다. 한편 컴퓨터 그래픽의 급속한 성장으로 인해, 진화된 구조해석 및 최적설계기법들을 이용하고 있다. 본 논문에서는 해상 풍력 터빈을 위한 자켓 구조물의 구조형상을 위상최적화 기법을 통하여 연구하였다. 이번 연구는 실제작동하중상태로 시뮬레이션을 위하여 다 하중으로 종속시켰으며, 최적화 목적 함수는 주어진 경계조건아래 컴플라이언스로 정의하였다. 최적화는 고유진동수와 체적을 구속함수로 사용하였으며, 1 단계 모델의 결과는 2 단계 구조를 위한 외형을 빠르게 볼 수 있도록 한다. 그 결과로 사각뿔대의 3D 모델은 위상최적화를 통하여 개발하였다.

• Structural Engineering and Mechanics
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• 제23권4호
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• pp.325-337
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• 2006

A hybrid structural design and optimization methodology that combines the strengths of genetic algorithms, local search techniques, and parallel computing is developed to evolve optimal truss systems in this research effort. The primary objective that is met in evolving near-optimal or optimal structural systems using this approach is the capability of satisfying user-defined design criteria while minimizing the computational time required. The application of genetic algorithms to the design and optimization of truss systems supports conceptual design by facilitating the exploration of new design alternatives. In addition, final shape optimization of the evolved designs is supported through the refinement of member sizes using local search techniques for further improvement. The use of the hybrid approach, therefore, enhances the overall process of structural design. Parallel computing is implemented to reduce the total computation time required to obtain near-optimal designs. The support of human-computer interaction during layout optimization and local optimization is also discussed since it assists in evolving optimal truss systems that better satisfy a user's design requirements and design preferences.

• 한국항공우주학회지
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• 제48권8호
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• pp.621-629
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• 2020

탑재 장비의 위치 결정 문제는 감항, 성능, 정비성, 환경요구사항 등의 다양한 기준을 고려해야 하는 복잡한 문제이다. 항공기의 기능이 복잡해짐에 따라 필요한 장비가 증가하고 있으며, 무인항공기는 조종사를 대신할 장비의 탑재로 더 많은 장비가 장착된다. 문제의 복잡성, 대상 장비의 수량 증가, 제한된 개발 기간 등으로 인하여 장비의 배치 결정은 설계자의 직관과 경험에 의존하는 부분이 크다. 최적화를 위해서는 정량적인 기준으로 평가가 필요하나 안전, 성능, 정비성 등의 기준은 정량적인 비교가 어렵거나 대상이 제한적인 한계가 있다. 본 연구에서는 장비의 장착과 정비를 고려하고 배치 모델을 순회판매원 문제로 단순화하고, 장비 간 연결 케이블의 중량이 최소가 되도록 유전알고리즘을 이용하여 최적화를 수행하였다. 최적화 결과를 전역 계산 결과와 비교하였을 때 더 적은 소요 시간으로 동일한 결과를 얻을 수 있었으며, Heuristic과 비교하여 개선됨을 확인하였다.

• 한국가스학회지
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• 제16권2호
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• pp.52-59
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• 2012

본 연구에서는 화재로부터 가장 효과적인 소화설비로 평가받고 있는 스프링클러 시스템에 대해 화재 시뮬레이션과 수리계획법에 기반을 한 최적 배치방법을 제안하였다. 사례연구로, $5.2m(L){\times}5.4m(W){\times}2.4m(H)$ 크기의 일반 주거지 형태를 대상공간으로 설정하고, 부주의로 폴리우레탄 소재의 소파에 불이 인화되어 화재가 전이되는 시나리오를 구성하였다. 그리고 스프링클러의 종류와 개수에 따른 소화속도, 온도변화, 표면 열방출률을 시뮬레이션을 통해 분석하고, 공간 균등배분 방법으로 설치된 스프링클러의 설치비와 화재 피해액의 정형화를 바탕으로, 수리계획법을 이용하여 최적 소화성능의 스프링클러 배치시스템을 얻을 수 있었다.

• 대한산업공학회지
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• 제38권3호
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• pp.173-181
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• 2012

The size and layout of user interface components need to be optimally designed in terms of reachability, visibility, clearance, and compatibility in order for efficient and effective use of products. The present study develops an ergonomic design method which optimizes the size and layout of user interface components using adaptive genetic algorithm. The developed design method determines a near-optimal design which maximizes the aggregated score of 4 ergonomic design criteria (reachability, visibility, clearance, and compatibility). The adaptive genetic algorithm used in the present study finds a near-optimum by automatically adjusting the key parameter (probability of mutation) of traditional genetic algorithm according to the characteristic of current solutions. Since the adaptive mechanism partially helps to overcome the local optimality problem, the probability of finding the near-optimum has been substantially improved. To evaluate the effectiveness of the developed design method, the present study applied it to the user interface design for a portable wireless communication radio.

• 소음진동
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• 제9권4호
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• pp.795-805
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• 1999

Rubber mounts so called grommets and pipes are two major paths of vibration transmission from a compressor, an important vibration source in an air conditioner, to the whole unit. A procedure of configuring the suction and discharge pipes of the compressor was developed in this paper so as to reduce the vibration transmission through the pipes as well as the grommets. Through investigating the effects of shapes and connecting disrections of pipe elements on vibration transmission, a guideline to configure the pipe layout, which enables to reduce vibration transmission, was proposed. The initial pipe layout by the guideline was optimized with the objective function, minimization of boty vibration transmission and the cost, and with the constraints to yield the final dimensions of the pipes. The procedure not only minimizes the transmitted force to the circumferential devices but enables to eliminate rubber blocks or dampers, which are generally used to avoid resonances of the pipe system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.1023-1026
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• 2007

Optimal damping layout of the constrained viscoelastic damping layer on beam is identified with temperatures by using a gradient-based numerical search algorithm. An optimal design problem is defined in order to determine the constrained damping layer configuration. A finite element formulation is introduced to model the constrained damping layer beam. The four-parameter fractional derivative model and the Arrhenius shift factor are used to describe dynamic characteristics of viscoelastic material with respect to frequency and temperature. Frequency-dependent complex-valued eigenvalue problems are solved by using a simple resubstitution algorithm in order to obtain the loss factor of each mode and responses of the structure. The results of the numerical example show that the proposed method can reduce frequency responses of beam at peaks only by reconfiguring the layout of constrained damping layer within a limited weight constraint.