• Proceedings of the Computational Structural Engineering Institute Conference
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.216-221
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• 2008

Shape design optimization for linear elasticity problem is performed using isogeometric analysis method. In many design optimization problems for real engineering models, initial raw data usually comes from CAD modeler. Then designer should convert this CAD data into finite element mesh data because conventional design optimization tools are generally based on finite element analysis. During this conversion there is some numerical error due to a geometry approximation, which causes accuracy problems in not only response analysis but also design sensitivity analysis. As a remedy of this phenomenon, the isogeometric analysis method is one of the promising approaches of shape design optimization. The main idea of isogeometric analysis is that the basis functions used in analysis is exactly same as ones which represent the geometry, and this geometrically exact model can be used shape sensitivity analysis and design optimization as well. In shape design sensitivity point of view, precise shape sensitivity is very essential for gradient-based optimization. In conventional finite element based optimization, higher order information such as normal vector and curvature term is inaccurate or even missing due to the use of linear interpolation functions. On the other hands, B-spline basis functions have sufficient continuity and their derivatives are smooth enough. Therefore normal vector and curvature terms can be exactly evaluated, which eventually yields precise optimal shapes. In this article, isogeometric analysis method is utilized for the shape design optimization. By virtue of B-spline basis function, an exact geometry can be handled without finite element meshes. Moreover, initial CAD data are used throughout the optimization process, including response analysis, shape sensitivity analysis, design parameterization and shape optimization, without subsequent communication with CAD description.

• Transactions of Materials Processing
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• 제21권4호
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• pp.265-270
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• 2012

In this study, a process design method for the multi-pass shape drawing is proposed with consideration of the drawing stress. First, the shape drawing load was calculated to evaluate the shape drawing stress, and the intermediate die shape was determined by using an electric field analysis and the average reduction ratio. In order to evaluate whether material yielding occurs at the die exit, the drawing stress was determined by using the calculated shape drawing load. Finally, FE-analysis and shape drawing experiments were conducted to validate the design of the multi-pass shape drawing process. From the results of the FE-analysis and shape drawing experiments, it was possible to produce a sound shape drawn product with the designed process. The dimensional tolerances of the product were within the allowable tolerances.

• Korean Journal of Computational Design and Engineering
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• 제15권6호
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• pp.440-448
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• 2010

At the early design stage, a designer would develop a design through reviewing various alternatives. However, the limitation of human information handling capacity restricts what makes various alternatives. A way to overcome the limitation is to create the alternatives with computer power and the generative design concept with computer has been used. For the generative design, even if a great deal of methodologies has been presented, the core of methodologies would be the process of shapes which examine interrelationship among shapes and how shape can be changed with the interrelationship. The interrelationship can be represented as rules. To represent the rule, the shape grammar is suggested by Stiny in 1972 with the article of "Shape Grammars and the Generative Specification of Painting and Sculpture". The aim of this paper is to present a way of using generative design based on shape grammar for generating alternatives in 3D manner.

• Journal of the Korean Society for Precision Engineering
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• 제10권3호
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• pp.87-96
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• 1993

In this study, the peak stress of a fuillet in elastic structure was optimized to have minimum value by using quadratic isoparametric element. The method of auomatic gridding was also developed along with shape algorithm and design element technique was adopted in selecting design variables. The computer program developed was combined with the Hooke-Jeeves direct algorithm of optimization techniques in order to minimize the peak stress of the fillet. The imployment of design element technique significantly cut down computer time by the reduction in design variables, and the opitmum fillet shape with uniform minimum stress was obtained by varying design variables along x and y directions in improving the shape compared to other results. By using automatic gridding, in which Bezier surfaces and Coons surfaces of cubic interpolation were employed, the irregular boundary was removed resulting in smoother anbd more accurate fillet shape possessing uniform minimum stress.

• Journal of the Korean Society of Costume
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• 제60권3호
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• pp.1-9
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• 2010

The purpose of this study is to develop Blue-Jean Design for Ideal Body Shape. The final aim of Fashion design is looks beauty of people by optical illusion. This study is based on Gestalt therapy and, is blue jeans design using optical illusion of vertical line for ideal beauty body image. Optical illusion for blue-jean design effect to achieve the ideal body shape. We can accumulate the preceding study for modern clothing from design and the related optical illusion effects. Vertical line stitches have all the advantages especially in pants design. I design blue jeans using optical illusion theory. The results of this study are as follows: First, Vertical line helps that jean has the long body shape effectively. Second, Jeans which have two or more vertical lines is more effective than simple Jean in order to make slim body shape. Third, Appropriate position of horizontal lines can be effective to make long body shape. Fourth, Top stitch, pin-tuck and pleats can be applied to vertical or horizontal lines instead of cutting lines.

• Transactions of Materials Processing
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• 제8권5호
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• pp.454-464
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• 1999

A new blank design method is proposed to predict the optimum initial blank shape in the sheet metal forming process. The rollback method for blank shape design takes the difference between the deformed blank contour and the target contour shape into account. the minimization object function R is proposed. Based on the method, a computer program composed of blank design module, FE-analysis module and mesh generation module is developed. The rollback method is applied to square cup, reentrant cross section, L-shaped cup drawing process with the flange of uniform size around its periphery to confirm its validity. The optimum initial blank shape is obtained from an arbitrary blank shape after several modifications. Good agreements are recognized between the numerical results and the published experimental results for initial blank shape and thickness strain distribution. It is concluded that the rollback method is an effective and convenient method for an optimum blank shape design.

• Transactions of Materials Processing
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• 제24권5호
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• pp.340-347
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• 2015

Multi-pass shape drawing is used to manufacture long products of arbitrary cross-sectional shapes. This process allows smooth surface finishes and closely controlled dimensions of the cross-sectional shape. Tube shape drawing for hollow type products provides material savings and weight reduction. The intermediate die shapes are very important in multi-pass tube shape drawing. In the current paper, the design method for the intermediate dies in a tube shape drawing process is developed using a die offset for corner filling (DOCF) method. Underfill defects are related to the radial velocity distribution of each divided section in the deformation zone. The developed intermediate die shape design was applied to the two-pass tube shape drawing with fixed mandrel for manufacturing a hollow linear motion (LM) guide rail. The proposed design method led to uniform and steady metal flow at each divided section. FE-simulations and experiments were conducted to validate the effectiveness of the proposed method in multi-pass tube shape drawing process.

• Journal of the Korean Society for Railway
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• 제10권2호
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• pp.124-130
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• 2007

The emphasis of this paper is to find out the changes in length of nose in line with speed improvement and changes of the tendency in the shape of the nose in line with time series based on the Shinkansen vehicle. The length of the nose on the lines of high speed tends to get longer, however there is no proportion between the speed and the nose according to optimal design that was designed to reduce micro-pressure wave and air resistance. The Shinkansen vehicles, according to the shape, can be classified in to an Advanced Paraboloid shape, a Sharp-nosed shape, a Flat-nosed shape and an Organic Double-edged shape and is gradually changing in the trend of diversity and distinction. Hereafter, the design of the nose will be developed better into the design that will comprehend identity of manufacturer, region and culture on the basis of optimized aerodynamic shape.

• The Journal of Korea Robotics Society
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• 제15권2호
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• pp.177-183
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• 2020

Collaborative Robot (Cobot) that can collaborate with humans by fusion with many advanced technologies among industrial robots in the industrial field are attracting attention. In this study, the engineers of Small and Medium Enterprises can directly participate in the cobot design, and ultimately, the possibility of deriving the shape design of the differentiated cobot was studied. The method applied to derive the shape design of differentiated cobot is 'Morphological Analysis'. First, the design elements of the form of cobots were derived as 'Link' and 'Joint'. In addition, by analyzing the image form of the Link and Joint of the existing cobot, a new form element of the Link and Joint was proposed. In order to quantitatively identify the most discriminating cobot shape design, FGI (Focus Group Interview) was conducted to derive image types of 4 Link and 3 Joint. Then, the most important 'Shape Combination' was carried out in morphological analysis, and 12 new cobot shape designs were drawn. Through this, the applicability of the morphological analysis method in the derivation of differentiated cobot shape design was examined.

• Journal of the Optical Society of Korea
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• 제13권2호
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• pp.286-293
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• 2009

In this paper, we present an optimal shape design method for a dielectric microlens which is used to focus an incoming infrared plane wave in wideband, by exploiting the finite difference time domain (FDTD) technique and the topology optimization technique. Topology optimization is a scheme to search an optimal shape by adjusting the material properties, which are design variables, within the design space. And by introducing the adjoint variable method, we can effectively calculate a derivative of the objective function with respect to the design variable. To verify the proposed method, a shape design problem of a dielectric microlens is tested when illuminated by a transverse electric (TE)-polarized infrared plane wave. In this problem, the design variable is the dielectric constant within the design space of a dielectric microlens. The design objective is to maximally focus the incoming magnetic field at a specific point in wideband.