• 대한기계학회논문집A
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• 제20권9호
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• pp.2800-2811
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• 1996

The deformation of a structure shall be called homologous, if a given geometrical relation holds, for a given number of structural points, before, during, and after the deformation. Some researchers have utilized the idea on structural design with finite element method. The approaches use the decomposition of the FEM equation or equality of eqality equations to obtain homologous deformation. However, weight reduction and response constraints such as stress, displacement or natural frequency cannot be considered by those theories. An optimization method solving the above problems is suggested to gain homologous deformation. Homology constraints can be considered under multiple loadindg conditions as well as a single loading condition. Homology index is defined for the multiple loading conditions Examples are solved to present the performances of the method.

• 대한기계학회논문집A
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• 제20권3호
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• pp.872-881
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• 1996

The concept of homology design has been devised for the application to large telescope structure by S.v.Hoerner. It is defined that the deformation of a structure shall be called homologous, if a given geometrical relation holds, for a given number of structural points, before, during, and after the deformation. Recently, the need of homology design in the structural design has been increase due to the required precision in the structure. Some researchers have utilized the theory on the structural design with finite element method in the late 1980s In the present investigation, a simple method using geometrical equality constraints is suggested to gain homologous deformation. The previous method is improved in that the decomposition of FEM eqation, which is very expensive, is not necessary. The basic formulations of the homology design with the optimization concept are described and several practical examples are solved to verify the usefulness and validity. Especially, a back-up structure of a satellite antenna is designed by the suggested method. The results are compared with those of existing researches.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.828-835
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• 2006

Spacer grid springs support the fuel rods in a nuclear fuel system. The spacer grid is a part of a fuel assembly. Since a spring has repeated contacts with the fuel rod, fretting wear occurs on the surface of the spring. Design is usually performed to reduce the wear. The conceptual design process for the spring is defined by using the Independence of axiomatic design and the design is carried out based on the direction that the design matrix indicates. For detailed design an optimization problem is formulated. In optimization, homologous design is employed to reduce fretting wear. The deformation of a structure is called homologous if a given geometrical relationship holds for a given number of structural points before, during, and after the deformation. In this case, the deformed shape of the spring should be the same as that of the fuel rod. 1bis condition is transformed to a function and considered as a constraint in the optimization process. The objective function is minimizing the maximum stress to allow a local plastic deformation. Optimization results show that the contact occurs in a wide range. Also, the results are verified by nonlinear finite element analysis.

• 전산구조공학
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• 제11권1호
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• pp.217-226
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• 1998

본 논문은 변위제약모드를 갖는 트러스구조물의 형태해석을 목적으로 하였으며, 이를 위하여 해의 존재조건과 무어-펜로즈(Moore-Penrose) 일반역행렬을 이용하였다. 또한, 수치해석과정에서의 변위제약모드로는 호몰로지변형(homologous deformation)을 고려하여 해석하였고, 다음으로 다양한 변위제약모드와 절점에 작용하는 하중비를 만족하는 구조물의 형태를 구하였다. 본 논문에서의 형태해석문제는 지정된 변위를 만족하는 구조물의 형태를 찾는 일종의 역문제(inverse problem)로서 일반적인 구조해석과정과는 반대되는 입장에서 접근하였다. 또한, 본 논문에서는 수치해석과정에서 근사해의 정도를 향상시키기 위하여 뉴튼-랩슨법을 사용하였고, 수치해석예제로서 부재의 배열형태에 따라 3가지모델을 선택하였으며, 이들 모델을 통하여 적용한 해석기법의 정확성과 효율성을 검증하였다.

• Journal of Computational Design and Engineering
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• 제1권1호
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• pp.1-12
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• 2014

In this paper, we propose a new method of reconstructing the hand models for individuals, which include the link structure models, the homologous skin surface models and the homologous tetrahedral mesh models in a reference posture. As for the link structure model, the local coordinate system related to each link consists of the joint rotation center and the axes of joint rotation, which can be estimated based on the trajectories of optimal markers on the relative skin surface region of the subject obtained from the motion capture system. The skin surface model is defined as a three-dimensional triangular mesh, obtained by deforming a template mesh so as to fit the landmark vertices to the relative marker positions obtained motion capture system. In this process, anatomical dimensions for the subject, manually measured by a caliper, are also used as the deformation constraints.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 봄 학술발표회 논문집
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• pp.101-109
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• 1998

Genetic Algorithm(GA), which is based on the theory of natural evolution, has been evaluated highly for their robust performances. The optimization problems on truss structures under the prescribed displacement are solved by using GA. In this paper, the homologous deformation of structures was proposed as the prescribed displacement. The shape analysis of structures is a kind of inverse problems different from stress analysis, and the governing equation becomes nonlinear. In this regard, GA was used to solve the nonlinear equation. In this study, the shape analysis method in which not only the positions of the objective nodes but also the layout and sectional area of the member are encoded to strings in the GA as design parameters of the structures is proposed.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1997년도 가을 학술발표회 논문집
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• pp.262-269
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• 1997

The purpose of this study is to survey the shape finding of the plane truss structures under the prescribed displacement mode by the shape analysis. The shape analysis is peformed by the existence condition of a solution and Moore-Penrose generalized inverse matrix, and the prescribed displacement mode is the homologous deformation of structures. The shape analysis of structures is a kind of inverse problem and become the problem of a nonlinear equation. Newton-Raphson method is used to improve the accuracy of approximated solution. To prove the accuracy and the effectiveness of this method, four different shape examples are analyzed.

• 대한기계학회논문집A
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• 제31권10호
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• pp.999-1008
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• 2007

The spacer grid set is a component in the nuclear fuel assembly. The set supports the fuel rods safely. Therefore, the spacer grid set should have sufficient strength for the external impact forces such as earthquake. The fretting wear occurs between the spring of the fuel rod and the spacer grid due to flow-induced vibration. Conceptual design of the spacer grid set is performed based on the Independence Axiom of axiomatic design. Two functional requirements are defined for the impact load and the fretting wear, and corresponding design parameters are selected. The overall flow of design is defined according to the application of axiomatic design. Design for the impact load is carried out by using nonlinear dynamic analysis to determine the length of the dimple. Topology optimization is carried out to determine a new configuration of the spring. The fretting wear is reduced by shape optimization using the homology theory. The deformation of a structure is called homologous if a given geometrical relationship holds before, during, and after the deformation. In the design to reduce the fretting wear, the deformed shape of the spring should be the same as that of the fuel rod. This condition is transformed to a function and considered as a constraint in the shape optimization process. The fretting wear is expected to be reduced due to the homology constraint. The objective function is minimizing the maximum stress to allow a slight plastic deformation. Shape optimization results are confirmed through nonlinear static analysis.