• 한국생산제조학회지
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• 제19권5호
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• pp.691-697
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• 2010

Reliability-based topology optimization (RBTO) is to get an optimal topology satisfying uncertainties of design variables. In this study, reliability-based topology optimization method is applied to the inner reinforcement of vehicle's hood based on BESO. A multi-objective topology optimization technique was implemented to obtain optimal topology of the inner reinforcement of the hood. considering the static stiffness of bending and torsion as well as natural frequency. Performance measure approach (PMA), which has probabilistic constraints that are formulated in terms of the reliability index, is adopted to evaluate the probabilistic constraints. To evaluate the obtained optimal topology by RBTO, it is compared with that of DTO of the inner reinforcement of the hood. It is found that the more suitable topology is obtained through RBTO than DTO even though the final volume of RBTO is a little bit larger than that of DTO. From the result, multiobjective optimization technique based on the BESO can be applied very effectively in topology optimization for vehicle's hood reinforcement considering the static stiffness of bending and torsion as well as natural frequency.

• 한국정밀공학회지
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• 제19권11호
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• pp.137-145
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• 2002

Electric vehicle body has to be subjected to uniform load and requires auxiliary equipment such as air pipe and electric wire pipe. Especially, the cross beam supports the weight of passenger and electrical equipments. a lightweight vehicle body is salutary to save operating costs and fuel consumption. Therefore this study is to perform the size and the shape optimization of crossbeam for electric vehicle using the method of topology optimization to introduce the concept of homogenization based on optimality criteria method which is efficient for the problem having the number of design variables and a few boundary condition. this provides the method to determine the optimum position and shape of circular hole in the cross beam and then can achieve the optimal design to reduce weight.

• Wind and Structures
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• 제34권3호
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• pp.291-301
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• 2022

Although mostly used in wind turbine market, single rotor wind turbines have problems with transportation and installation costs due to their large size. In order to solve such problems, multi-rotor wind turbine is being proposed; however, light weight design of multi-rotor wind turbine is required considering the installation at offshore or deep sea. This study proposes the systematic design process of the multi-rotor wind turbine focused on its supporting structure with simultaneous consideration of static and dynamic behaviors in an ideal situation. 2D and successive 3D topology optimization process based on the density method were applied to minimize the compliance of supporting structure. To realize the conceptual design obtained by topology optimization for manufacturing feasibility, the derived 3D structure was modified to have shell structures and optimized again through parametric design using the design of experiments and the response surface method for detail design of their thicknesses and radii. The resultant structure was determined to satisfy the stress and the buckling load constraint as well as to minimize the weight and the resultant supporting structure were verified numerically.

• 대한기계학회논문집A
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• 제27권11호
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• pp.1925-1932
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• 2003

Topology optimization is widely accepted as a conceptual design tool for the product design. Since the resulted layout of the topology optimization is a kind of digital images represented by the density distribution, the seamless process is required to transform digital images to the CAD model for the practical use. In this paper, the general process to construct a CAD model is developed to apply for topology images based on elements. The node density and the morphology technique are adopted to extract boundary contour of the shape and remove the noise of images through erosion and dilation operation. The proposed method automatically generates point data sets of the geometric model. The process is integrated with Pro/Engineer, so that the engineer in practice can directly handle with curves or surfaces form digital images.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.938-941
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• 2006

We present a new design method of one-dimensional multi-layered acoustic foams for transmission loss maximization by topology optimization. Multi-layered acoustic foam sequences consisting of acoustic air layers and poroelastic material layers are designed for target frequency values. For successful topology optimization design of multi-layered acoustic foams, the material interpolation concept of topology optimization is adopted. In doing so, an acoustic air layer is modeled as a limiting poroelastic material layer; acoustic air and poroelastic material are handled by a single set of governing equations based on Biot's theory. For efficient analysis of a specific multi-layered foam appearing during optimization, we do not solve the differential equations directly, but we use an efficient transfer matrix approach which can be derived from Biot's theory. Through some numerical case studies, the proposed design method for finding optimal multi-layer sequencing is validated.

• Composites Research
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• 제32권5호
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• pp.243-248
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• 2019

As demand of light weight in the automotive industry has increased, the cowl cross member has been investigated using various methods to change the material. Conventionally, a cowl cross member has been made of steel and aluminum, but recently researchers tested multi-material such as aluminum and plastic. We studied a new model of the cowl cross member made of composite and non ferrous materials. For products with a high degree of freedom in design, generally, the method of topology optimization is advantageous and for the partial bracket part of the cowl cross member had a degree of freedom in the design, a topology optimization is appropriate. Considering the characteristics of the cowl cross members, we need research to minimize the weight while having the performance of noise, vibration and harshness(NVH). Taking the mounting status of the product into consideration, we used an assembly model to optimize the cowl cross member. But this method took too much time so we considered simple cowl cross member assemble conditions using the direct matrix input method(DMI) with the Craig-Bampton Nodal Method. This method is capable of considering the status of the assembly without assembling the model, which reduced the solving time and increased the accuracy comparison with a cowl cross member without DMI.

• 한국전산구조공학회논문집
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• 제28권1호
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• pp.9-18
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• 2015

본 논문에서는 애조인 설계민감도(DSA)를 사용하여 평형상태의 열전도문제에서 수치적으로 얻어진 위상 최적설계를 실험적으로 검증하였다. 애조인 변수법을 이용하면 해석에서 사용되었던 행렬시스템을 애조인 문제를 풀 때 그대로 활용가능하기 때문에 설계민감도를 얻는데 필요한 계산을 매우 효율적으로 수행할 수 있다. 위상 최적설계를 위해서 설계변수는 정규화된 재료밀도 함수로 정하였다. 목적함수는 구조물의 열 컴플라이언스이고 제한조건은 허용 가능한 재료량이다. 또한 열화상카메라를 활용하여 이러한 위상 최적설계로 얻어진 수치적 결과를 부피가 동일하도록 직관적으로 설계된 디자인과 비교하여 실험적으로 검증하였다. 위상 최적설계로 얻어진 결과를 실제로 제작하기 위해 간단한 수치기법을 통해 점 정보로 변환한 후 역설계 상용프로그램을 이용하여 CAD 모델링을 수행한다. 이를 바탕으로 위상 최적설계 결과를 CNC(Computerized Numerically Controlled machine tools) 선반으로 제작하였다.

• 한국산학기술학회논문지
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• 제10권6호
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• pp.1207-1213
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• 2009

본 논문에서는 다양한 네트워크의 통합관리를 위한 네트워크토폴로지를 설계하는 방법을 제안한다. 이를 위해 TMN-DCN 디바이스를 정의하고 이를 주요요소로 이용하기로 한다. 이 때 관리정보량이 주요변수가 된다. 또한 네트워크 관리특성의 주요요소로 떠오르는 네트워크 서바이벌특성이 포함되는 네트워크 토폴로지의 간단한 설계방법을 제안한다. 이들 방법은 링크비용을 최소로 하면서 전체 트래픽 량을 지원할 수 있다. 실제 설계 예를 통하여 그 결과를 확인한다. 설계방법이 간단하게 제안 되었지만 서바이벌 특성구현과 관리 네트워크설계에 관한 보편적으로 적용할 수 있는 최적의 설계알고리듬이 존재하지 않기에 본 논문에서 제안된 설계방법이 실제 관리망의 구축 시 활용될 수 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1413-1418
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• 2003

In this study, the topology optimization is applied to the design of a piezoelectric microactuator satisfying the specific mean transduction ratio(MTR). The optimization problem is formulated to minimize the difference between the specified and the current mean transduction ratio. In order to analyze the response of the piezoelectric-structure coupled system, both the structural and the electric potential are considered in the finite element method. The optimization problem is resolved by using Sequential Linear Programming(SLP) and the results of test problems show that the design of a piezoelectric microactuator with specified mean transduction ratio can be obtained.

• Structural Engineering and Mechanics
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• 제34권5호
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• pp.581-595
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• 2010

This paper presents topology optimization of geometrically and materially nonlinear structures using a bi-directional evolutionary optimization (BESO) method. To maximum the stiffness of nonlinear structures under prescribed design load, the complementary work is selected as the objective function of the optimization. An optimal design can be obtained by gradually removing inefficient material and adding efficient ones. The proposed method can be applied to a series of geometrically and/or materially nonlinear structures. The results show considerable differences in topologies and stiffness of the optimal designs for linear and nonlinear structures. It is found that the optimal designs for nonlinear structures are much stiffer than those for linear structures when large design loads (which result in significantly nonlinear deformations) are applied.