• 대한기계학회논문집A
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• 제26권8호
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• pp.1512-1519
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• 2002

Most of mechanical failures are caused by repeated loadings and therefore they are strongly related to fatigue. To avoid the failures caused by fatigue, determination of an optimal shape of a structure is one of the very important factors in the initial design stage. Shape optimization fer two types of specimens, which are very typical ones in opening mode in fracture mechanics, was accomplished by the linear elastic fracture mechanics and the growth-strain method in this study. Also shape optimization for a cantilever beam in mixed mode was carried out by the same techniques. The linear elastic fracture mechanics was used to estimate stress intensity factors and fatigue lives. And the growth-strain method was used to optimize the shape of the initial shape of the specimens. From the results of the shape optimization, it was found that shapes of two types of specimens and a cantilever beam optimized by the growth-strain method prolong their fatigue lives significantly. Therefore, it was verified that the growth-strain method is an appropriate technique for shape optimization of a structure having a crack.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.83-90
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• 2001

In the design of cable structures it is necessary to know the initial shape of the cable. The geometrical condition and the equilibrium equation of the cable are needed. Because the equilibrium equation is expressed by the simultaneous equations of second order, it is almost impossible to solve with elimination method. To solve it, we must use iteration method. In this study, the algorithm which can reduce the number of iteration and calculate shape of the cable is developed and compared with measured data through the laboratory test and the results represent good agreements.

• Journal of Mechanical Science and Technology
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• 제17권11호
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• pp.1665-1673
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• 2003

We propose an image-based three-dimensional shape determination system. The shape, and thus the three-dimensional coordinate information of the 3-D object, is determined solely from captured images of the 3-D object from a prescribed set of viewpoints. The approach is based on the shape-from-silhouette (SFS) technique, and the efficacy of the SFS method is tested using a sample data set. The extracted three-dimensional shape is modeled with polygons generated by a new iterative triangulation algorithm, and the polygon model can be exported to commercial software. The proposed system may be used to visualize the 3-D object efficiently, or to quickly generate initial CAD data for reverse engineering purposes, including three dimensional design applications such as 3-D animation and 3-D games.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.133-137
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• 2002

This paper summarizes the results of a numerical study conducted to analyze the determination of optimum blank diameter on material flow and thread profile for Spindle Screw in external thread rolling. Initial blank diameter affect a quality of Spindle Screw in thread rolling process. Therefore, it is very important to determine the optimum blank diameter in thread rolling process. In order to determine the optimum blank diameter, this paper suggest the calculating method of initial blank diameter considering real shape of tooth. The finite element code DEFORM is applied to analyze the metal flow of tooth. then the analytical results are verified by experiment of thread rolling for Spindle Screw.

• 한국전산구조공학회논문집
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• 제25권1호
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• pp.101-108
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• 2012

사장교 시스템의 초기형상해석이라 함은 주형의 수직 처짐과 휨모멘트, 주탑의 수평변위와 휨모멘트를 최소화하면서, 고정하중과 평형을 이룰 수 있는 케이블의 장력과 무응력길이를 결정하는 방법으로 이 때, 케이블이 정착되는 주형의 수평위치, 주탑의 수직위치가 목표형상에 부합할 필요가 있다. 본 연구에서는 고정하중을 받는 사장교의 초기형상을 효율적이고 합리적으로 결정하기 위하여 개선된 초기부재력법과 TCUD법의 비교연구 결과를 제시하고자 한다. 주형과 주탑의 케이블 정착부에서 힘의 평형조건을 이용하여 주형의 수직처짐과 주탑의 수평변위를 효과적으로 제어할 수 있는 절점평형법을 초기 부재력법에 적용하여 초기치에 민감한 기존 초기부재력법을 개선한다. 또한 개선된 TCUD법을 이용한 초기형상해석 수행결과와 비교함으로서 두 방법의 정확성을 입증하고자 한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.585-588
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• 2005

Many process parameters have an effect on the auto-body panel forming process. A well designed blank shape causes the material to flow smoothly, reduces the punch and yields a product with uniform thickness distribution. Therefore, the determination of an initial blank shape plays the important role of saving time and cost in the auto-body panel forming process. For these reasons, some approaches to estimate the initial blank shape have been implemented, in this paper The one-step approach using a finite element inverse method will be introduced to predict the optimal forming with changing of blank pressure the developed program is applied to auto-body panel forming.

• 한국구조물진단유지관리공학회 논문집
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• 제9권2호
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• pp.137-146
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• 2005

본 연구는 형상반복법과 수정 라그랑쥐 방법으로 사장교 케이블의 초기장력과 기준길이를 계산하였다. 사장교의 거더와 주탑은 3차원 frame 요소로, 케이블은 비선형 트러스요소와 Ernst의 케이블 요소로 이상화하였다. 본 연구의 유한요소법에 의한 케이블의 초기장력과 실무에서 사용하는 시산법에 의한 케이블의 장력을 비교한 결과, 전자의 경우가 후자의 경우보다 적음을 알 수 있었다. 케이블의 기준길이는 비선형 트러스요소를 사용한 해석결과와 Ernst의 케이블 요소를 사용한 해석결과를 비교하였으며 두 가지 해석결과가 거의 일치함을 알 수 있었다. 또한 기준길이는 초기장력값을 나타내는 단순교의 지간과 거의 일치함을 알 수 있었다. 따라서 케이블의 기준 길이는 본 연구로부터 얻은 초기장력을 가진 단순보의 호의 길이를 나타냄을 알 수 있었다.

• 대한조선학회논문집
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• 제44권5호
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• pp.517-525
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• 2007

This paper presents how to approximate an optimal shape of roll bending process in the fabrication of a curved shell plate. The roll bending process usually makes the cylindrical or conic shape from an initial flat plate. It means that the final shape is developable or its surface representation has zero Gaussian curvature. The fabrication shape is important in order to find process parameters of roil bending. An optimal concept is used to determine the developable fabrication shape which is in the closest proximity to the design surface or the given shell plate and is subject to developability. The results and the efficiency of this algorithm are evaluated by applying to some shell plates. Furthermore, the fabrication shape will be fundamental information for other process parameters of roll bending such as the vertical displacement of the center roller and the rolling directions.

• 대한기계학회논문집A
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• 제24권4호
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• pp.907-915
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• 2000

The movement of teeth and initial stress associated with the treatment of orthodontics have been successfully studied using the finite element method. To reduce the effort in preprocessing of finite element analysis, we developed two types of three-dimensional finite element models based on the standard teeth model. Individual malocclusions were incorporated in the finite element The movement of teeth and initial stress associated with the treatment of orthodontics have been successfully studied using the finite element method. To reduce the effort in preprocessing of finite element analysis, we developed two types of three-dimensional finite element models based on the standard teeth model. Individual malocclusions were incorporated in the finite element models by considering the measuring factors such as angulation, crown inclination, rotation and translations. The finite element analysis for the wire activation with a T-loop arch wire was carried out. Mechanical behavior on the movement and the initial stress for the malocclusion finite element model was shown to agree with the objectives of the actual treatment. Finite element models and procedures of analysis developed in this study would be suitably utilized for the design of initial shape of the wire and determination of activation displacements.

• 대한기계학회논문집A
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• 제20권11호
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• pp.3387-3397
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• 1996

The Hub is an auto mobile component used as aircon clutch. The important aspects in cold forging of the Hub with complex geometry are the design of an initial shape of the workpiece, the possibility of the forming by one-stage operation and the determination of number of performs, etc. Based on the systematic procedure of process sequence design, in this paper, the forming operation of cold forged part of the Hub is designed by the rigid-plastic finite element method. The two design criterion of geometrical filling without defect and an even distribution of effective strain in final product are investigated in controlling the initial shape of the workpiece and preform configuration. It is noted that one preforming operation is required in order to obtain final product of the Hub.