• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1334-1337
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• 2007

A steel pallet to carry lighter logistic articles is developed based on the DFSS(design for Six Sigma) methodology. Combining the conventional DFSS(Design For Six Sigma) methodology with that of VE(Value Engineering) is the novel feature of this paper to achieve maximum cost reduction. In this paper, systematical steps to achieve the required structural spec's are presented by conventional DMEDI(Define-Measure-Explore-Develop-Implement) process. To imply the target costing, evaluation of functions consisting of the pallet has been performed by value methodology. Then best design concept is selected in the Explore step, following structural optimization utilizing FEM. Finally the performance of prototype is investigated by pilot test in the Implement step. The developed steel pallet is being commercialized in the fields of automated ware house.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.218-225
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• 2004

A study has been performed to investigate the applicability of the high-strength steel to the medium-span composite girder bridges. A two- and four-girder simple and continuous bridges are considered. A proper span-to-depth ratio for the model bridges with SM490 and SM570 was evaluated by using the section optimization program, respectively. For the determined span-to-depth ratio, deflections and fatigue performance were also investigated. It was acknowledged that the high-strength steel reduces the weight of girder but the increase of deflection and fatigue stress should be considered especially in the positive moment area.

• Structural Engineering and Mechanics
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• 제54권4호
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• pp.665-691
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• 2015

This study aims at comparing the optimum design of two common types open web expanded beams: with hexagonal openings, also called castellated beams and beams with circular openings referred to as cellular beams. The minimum weights of both beams are taken as the objective functions while the design constraints are respectively implemented from The Steel Construction Institute Publication Numbers 5 and 100. The design methods adopted in these publications are consistent with BS5950 parts. The formulation of the design problem considering the limitations of the above mentioned turns out to be a discrete programming problem. Improved harmony search algorithm is suggested to compare the optimum design of mentioned web-expanded beams to analysis the performance of both beams. The design algorithms based on the technique select the optimum Universal Beam sections, dimensional properties of hexagonal and circular holes and total number of openings along the beam as design variables.

• Structural Engineering and Mechanics
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• 제35권5호
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• pp.539-554
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• 2010

Light weight superstructure is beneficial for bridges in remote areas and in emergency erection. In such weight sensitive applications, combination of fibre reinforced plastics (FRP) as material and box-girders as a structural system have great scope. This combination offers various options to tailor structure and its elements but this flexibility poses greater challenge in optimum design. In this paper a procedure is derived for a generalised optimum design of FRP box-girder bridges, using genetic algorithms (GA). The formulation of the optimum design problem in the form of objective function and constraints is presented. Size, configuration and topology optimization are done simultaneously. A few optimum design studies are carried out to check the performance of the developed procedure and to get trends in the optimum design which will be helpful to the new designers.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.465-468
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• 2004

The performance of the piezoelectric patches as vibration control elements depends on the shunting electronics which are designed to dissipate vibration energy through a resistive element. In this study, tuning of the shunting circuits is performed based on the wave propagation characteristics. Optimization of the electronic component is performed depending on the dynamic and geometric properties which include boundary conditions and position of the shunted piezoelectric patch relative to the structure. The developed tuning methods showed superior capabilities in minimizing structural vibration and noise radiation compared to other tuning methods. The tuned circuits are relatively insensitive to changes in modal properties and boundary conditions.

• 한국전산구조공학회논문집
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• 제31권2호
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• pp.79-85
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• 2018

기존의 한방향 펌프는 순환과 배수를 위해 각각의 모터를 사용하지만, 양방향 펌프는 하나의 모터로 모터의 회전 방향에 따라 배수와 순환이 모두 가능하므로 원가절감이 가능하다. 하지만 양방향 펌프는 배수와 순환 시 펌프 케이싱 내부에서 역류와 흡입이 발생하여 유입된 물이 각각 배출구와 순환구로 원활하게 유출되지 못하는 단점이 있다. 본 연구에서는 주효과 분석을 통해 배출과 순환 시 유출되는 유량과 토크에 주요한 영향을 미치는 인자를 설계변수로 선택하여 실험계획법, 근사모델, 그리고 최적설계를 통해 펌프 케이싱 형상을 최적화함으로써 역류와 흡입은 개선하고 펌프의 토크 대비 배출구와 순환구의 유량을 증가시키는 효과를 거두었다.

• Earthquakes and Structures
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• 제22권1호
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• pp.95-107
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• 2022

This paper introduces a novel, rigorous, and efficient probabilistic methodology for the performance-based optimal design (PBOD) of semi-active tuned mass damper (SATMD) for seismically excited nonlinear structures. The proposed methodology is consistent with the modern performance-based earthquake engineering framework and aims to design reliable control systems. To this end, an optimization problem has been defined which considers the parameters of control systems as design variables and minimization of the probability of exceeding a targeted structural performance level during the lifetime as an objective function with a constraint on the failure probability of stroke length damage state associated with mass damper mechanism. The effectiveness of the proposed methodology is illustrated through a numerical example of performance analysis of an eight-story nonlinear shear building frame with hysteretic bilinear behavior. The SATMD with variable stiffness and damping have been designed separately with different mass ratios. Their performance has been compared with that of uncontrolled structure and the structure controlled with passive TMD in terms of probabilistic demand curves, response hazard curves, fragility curves, and exceedance probability of performance levels during the lifetime. Numerical results show the effectiveness, simplicity, and reliability of the proposed PBOD method in designing SATMD with variable stiffness and damping for the nonlinear frames where they have reduced the exceedance probability of the structure up to 49% and 44%, respectively.

• 한국강구조학회 논문집
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• 제17권6호통권79호
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• pp.661-672
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• 2005

본 연구에서는 많은 양의 함수 계산을 요구하는 확률론적 최적화 기법을 보다 효과적으로 강구조물에 적용하여 수행하고자 한다. 다양한 과학, 응용공학 분야에서 많은 시간이 소요되는 과정을 대체하는데 효과적인 도구로 출현한 인공신경망을 최적화 과정 중 많은 수의 유한요소 해석이 요구되는 재해석 문제에 적용함으로서 유한요소법의 평형방정식의 해의 근사해를 추정하여 재해석과정을 보다 간단하고 용이하게 수행하고자 한다. 또한 이용된 인공신경망의 학습효과의 개선을 위해 유전알고리즘을 적용한다. 확률론적 구조최적화 기법으로는 진화론적 방법에 기초한 알고리즘을 사용한다. 수치 예로써 전형적인 체적(중량)문제와 실 경비함수를 목적함수로 갖는 강구조물 모형에 본 연구의 알고리즘을 적용하여 본 알고리즘의 적용성과 타당성을 증명하였다.

• Structural Engineering and Mechanics
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• 제67권6호
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• pp.643-658
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• 2018

In this paper, we introduce a new framework for running the finite element (FE) packages inside an online Loop together with MATLAB. Contrary to the Hardware-in-the-Loop techniques (HiL), in the proposed Software-in-the-Loop framework (SiL), the FE package represents a simulation platform replicating the real system which can be out of access due to several strategic reasons, e.g., costs and accessibility. Practically, SiL for sophisticated structural design and multi-physical simulations provides a platform for preliminary tests before prototyping and mass production. This feature may reduce the new product's costs significantly and may add several flexibilities in implementing different instruments with the goal of shortlisting the most cost-effective ones before moving to real-time experiments for the civil and mechanical systems. The proposed SiL interconnection is not limited to ABAQUS as long as the host FE package is capable of executing user-defined commands in FORTRAN language. The focal point of this research is on using the compiled FORTRAN subroutine as a messenger between ABAQUS/CAE kernel and MATLAB Engine. In order to show the generality of the proposed scheme, the limitations of the available SiL schemes in the literature are addressed in this paper. Additionally, all technical details for establishing the connection between FEM and MATLAB are provided for the interested reader. Finally, two numerical sub-problems are defined for offline and online post-processing, i.e., offline optimization and closed-loop system performance analysis in control theory.

• 대한기계학회논문집A
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• 제37권6호
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• pp.769-774
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• 2013

가스터빈엔진의 핵심 부품인 디스크와 블레이드는 고효율, 수명주기 동안의 운용비 최소화 등의 요구조건으로 고온의 터빈입구 온도, 고압축비, 고속 환경에서 지속적으로 운용된다. 이러한 가혹한 환경에서의 구조 안전성을 평가하기 위해서는 재료 모델링과 유한요소해석 기법 등이 필수적이며 더 나아가 형상최적화가 반드시 요구된다. 본 연구에서는 터빈 디스크의 구조 건전성을 평가하기 위해 2 차원 축 대칭 및 섹터 모델을 생성하고, 열-구조 연성해석과 접촉 해석을 포함한 유한요소 해석을 수행하고자 한다. 이를 근거로 터빈 디스크에서 구조적으로 취약한 2 개의 영역인 디스크 보어와 디스크와 블레이드의 연결 부위인 도브테일에 대해 형상변수 고찰을 하고자 한다. 최종적으로 형상변수 결과를 기초로 한 개선된 디스크 형상을 제안함과 동시에 좀 더 정교한 형상최적화가 필요함을 확인한다.