• 한국자동차공학회논문집
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• 제8권1호
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• pp.135-147
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• 2000

Section design of vehicle structure has been developed by two methods. One is the section property method which uses section property as a design variable. This method shows the tendency of an optimum section approximately. The other method is the section shape method which utilizes geometric parameter of section as a design variable. Practical solutions are obtained by this method. However, it is very expensive for large-scale problems due to the large number of geometric parameters. These two methods are compared through several sample problems. The finite element method is used for the structural and sensitivity analyses. The results are analyzed based on the number of function evaluations, the quality of cost function, the complexity of programing, and etc. The applications of both methods are also discussed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.337-340
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• 2008

The cross section shape of intermediate die is one of important parameters to obtain dimensional accuracy of final product in shaped drawing process. Until now it has been designed by the experience or trial and error of the expert. In this study, the cross section shape of intermediate die fur spline shape is determined by the electronic field analysis, shape factor method. The result of the electronic field analysis, shape factor method has been compared with that of the present method. The effects of cross section shape on the dimensional accuracy were investigated by using FE analysis. And then the multi-stage shaped drawing experiments were performed to verify the results of FE analysis. As a result, the cross section shape from the electronic field analysis had the good dimensional accuracy. The electronic field analysis can be used for the method to obtain the cross section shape of intermediate die in shaped drawing process.

• 소성∙가공
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• 제18권4호
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• pp.323-328
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• 2009

The prediction of drawing load is very important in the drawing process. However, it is not easy to calculate the drawing load for the shape drawing process through a theoretical model because of a complex arbitrary final cross section shape. The purpose of this study is to predict drawing load in shape drawing process. The cross section of product is divided with small angle as much as similar with fan-shape. The drawing load of each section was calculated by theoretical model of round to round drawing process. And the shape drawing load was determined by summation of drawing load of each section. The effectiveness of the proposed method was verified through the FE analysis and shape drawing experiment. It had a good agreement between proposed method, FE analysis and experiment within about 3% errors.

• 한국자동차공학회논문집
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• 제19권2호
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• pp.117-124
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• 2011

Valve springs with non-circular cross-section are widely used in automotive engines. Because of the reduced height, the oval cross-section provides some merits in its install height and stress distribution. This paper introduces a new method to generate optimal shape of the non-circular cross-section. For given width and height, arbitrary shape of the cross-section are described using the Hermite spline curves. Cross-section area and maximum stress level are chosen as performance indices, and nonlinear optimization problems are formulated with inequality constraints. Compared to a production spring wire, cross-section area can be reduced about 2.4 [%] without increasing maximum stress level. In addition, the other approach gives an optimum cross-section which reduces maximum stress level of 2.0 [%] without increasing cross-section area.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.185-186
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• 2021

In Korea, many buildings are built with underground spaces and cast-in-place pile method is mostly applied in the temporary retaining walls for the underground space construction. A H-shaped steel section is generally embedded in the soldier pile in the C.I.P method. In this study, a new and economical section with high strength steel replacing the H-shaped section was proposed and its flexural capacity was evaluated experimentally. The new section is the concrete-filled composite section with pentagonal thin plate and thick flange plate. Test results showed that the proposed section has an excellent flexural strength and ductility.

• 한국분말재료학회지
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• 제2권2호
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• pp.135-141
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• 1995

As the first step of study on fabrication of ceramic powders from phytoliths in rice, especially in rice husks, pulverization method of rice husks and the properties of milled rice husks were investigated. Impact methods, such as ball milling, were not meaningful for pulverizing elastic and thin fabric structure of rice husks. The most effective one was cutting method. In the present work, a rotating knife cutting method was applied to pulverizing rice husks. A 40-mesh screen was inserted under the rotating knives. The most portion of the milled powder was found in -50/+100 mesh section. Morphology of the milled rice husks revealed that the husks larger than 70 mesh were flake-like shape, at -70/+100 mesh section relatively equi-axed shape, at -170/+325 mesh section rod-like shape, and below 325 mesh section dust-like shape. Tap density of raw rice husks was about 0.1 $g/cm^3$, while those of milled rice husks were over $0.4 g/cm^3$. This meant that, for a given volume of reactor, raw material charge can be increased more that 4 times when using milled rice husks than unmilled one. True densities of unmilled and milled rice husks were higher than $1.4 g/cm^3$, and increased with decreasing milled sizes.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1996년도 춘계학술대회논문집
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• pp.16-22
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• 1996

Two kinds of blank shapes, optimum and square, are adopted to investigate formbility. Optimum blank shape is determined to construct an L-shape cup with uniform height and without flange part. For this purpose , rigid-plastic FEM analysis is applied with backward tracing technique. Maximum cup detph and strain distribution are measured experimetally for the products of the two kinds of blank shapes, which are optimum and square.It is confirmed that deeper cup without severe thickness reduction can be obtained fro the optimum shape.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2379-2382
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• 2003

This paper describes the design, implementation and results of a unified non-rigid image registration method for the purposes of 3D shape reconstruction from serial section images. The proposed method uses active contour-based segmentation and compensation of radial distortion. Experimental results show that multiple images can be segmented and reconstructed by active single contour as well as intra- and inter-section registration.

• 한국안전학회지
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• 제28권6호
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• pp.36-41
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• 2013

Previous study showed that delamination region in concrete structures can be successfully visualized using mode shapes of delaminated concrete section. However, modal tests for this purpose to obtain mode shapes of the delaminated concrete section may not be applicable in practice since, to correctly obtain the mode shapes of the section, the location and the shape of the delamination region in a structure should be known in advance. Unfortunately those are normally unknown in a real structure. Therefore, a moving forward test method may be useful to obtain the mode shapes of the concrete section when the location and the shape of the delamination region are not known. In this study, impact-echo testing based mode shape estimation technique is proposed and experimentally validated for visualization of delamination region.

• 대한기계학회논문집
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• 제5권3호
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• pp.199-206
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• 1981

This paper presents a method of calculation of the stresses, the strains and the deflections due to welding in L shape and in T shape. Using step by step method of plasticity and establishing the equilibrium conditions in section, we calculated thermal stresses and strains during welding and in the final step of calculation we got the residual stresses, strains and the deflections due to welding. Also we measured the stresses and the strains with hole-drilling method and compared the results with the method of calculation presented in this paper. Because of its symmetry of section, the deflection due to welding in T shape is generally much less than that in L shape. The residual stresses are tensile in welded joints and HAZ, and compressive in base metal as butt welding of plates, but the compressive stresses in base metal decrease repidly as the points are away from welded joint except horizontal plates of T shape. The theoretical method of calculaiton presented in this paper coincides faily well with the experiment.