• Transactions of Materials Processing
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• v.10 no.5
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• pp.389-395
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• 2001

An inverse finite element approach is employed for more capability to design the optimum blank shape from the desired final shape with small amount of computation time and effort. For multi-stage deep-drawing processes with large aspect ratio, numerical analysis is extremely difficult to carry out due to its complexities and convergence problem. as well as tremendous computation time. In this paper, multi-stage finite element inverse analysis is applied to multi-stage rectangular cup drawing processes to calculate intermediate blank shapes and strain distributions in each stages. Deformation history of the previous stage is considered in the computation. Finite element patches are used to describe arbitrary intermediate sliding constraint surfaces.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.144-149
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• 2005

This study presents the method of extracting shape design data on any aspheric lens by reverse engineering. The design formula fur aspheric lenses is needed in almost all of the design, manufacture and measuring processes. The difficulty in designing the lens lies in the fact that it uses a complex formula for the aspheric surface, and many of the preliminary design values must be selected before actually inserting them into the formula. If the values could be extracted from an aspheric lens for which the structural design information is unknown and used in designing other lenses of similar characteristics, the difficulties in designing and measuring aspheric lens could be reduced. Therefore, in this study, the concept of reverse engineering was applied to demonstrate the method of extracting shape design information of aspheric lens from an arbitrary aspheric lens.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.489-496
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• 1998

The single layer latticed domes have various behaviors with each geometrical shape and scale, and they are affected by vertical component as well as horizontal component of the dynamic load. And they represent ye different earthquake responses under each ground acceleration compared with another structural systems. Generally, all of the members of latticed domes undergo three dimensional deflections if they are subjected to arbitrary one dimensional horizontal load under earthquake motions. And their response characteristics are very different to their shapes, rise/span ratios, and damping mechanisms. In this study, the earthquake response behavior is verified according to the factor of each shape, rise/span ratio, and damping ratio of latticed domes, which undergo horizontal and vertical earthquake motions by numerical approaches.

• Korean Journal of Computational Design and Engineering
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• v.3 no.4
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• pp.293-303
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• 1998

The objective of this study is to develop a PC level freeform surface modeling system which explicitly represents information of part geometry. Surface modeler uses nonuniform rational B-spline (NURBS) function with nonuniform knot vector for the flexible modeling work. The results of this study are as follows. 1) By implementation surface modeler through applying representation scheme proposed to represent free-form surface explicity, the technical foundation to develop free-from surface modeling system using parametric method. 2) Besides the role to model geometric shape of a surface, geometric modeler is developed to model arbitrary geometric shape. By doing this, the availability of the modeling system is improved. Geometric modeler can be utilized application fields such as collision test of tool and fixture, and tool path generation for NC machine tool.

• ETRI Journal
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• v.21 no.1
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• pp.40-54
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• 1999

In this paper, we describe a new trademark retrieval system based upon the content or the shape of trademark. The system has an on-line graphical user interface for the World Wide Web (WWW) that allows user to provide a query in forms of a sketch or a visual image to search for similar trademarks from database. User interfaces for the WWW were implemented by utilizing HTML and Java applets. The query can occur in arbitrary size and orientation. A shape representation scheme invariant to scale and rotation was developed to measure the similarity between two trademarks using the magnitude of Zernike moments as a feature set. Performance evaluation has been carried out with a database of 3,000 trademarks. It takes only about 0.6 second for the retrieval on a 200 MHz Pentium PC. The average recall of the original one among top 30 candidates queried by noisy or deformed images was 100%.

• Structural Engineering and Mechanics
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• v.7 no.3
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• pp.259-276
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• 1999

An analytical solution for the shape functions of a beam segment supported on a generalized two-parameter elastic foundation is derived. The solution is general, and is not restricted to a particular range of magnitudes of the foundation parameters. The exact shape functions can be utilized to derive exact analytic expressions for the coefficients of the element stiffness matrix, work equivalent nodal forces for arbitrary transverse loads and coefficients of the consistent mass and geometrical stiffness matrices. As illustration, each distinct coefficient of the element stiffness matrix is compared with its conventional counterpart for a beam segment supported by no foundation at all for the entire range of foundation parameters.

• Journal of Korean Association for Spatial Structures
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• v.23 no.1
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• pp.15-23
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• 2023

In this work, we deal with the feasibility of structural topology optimization for beam designs using retrofits that optimally allocates the reinforcement to the web under the condition that designers set bolt regions for H-beams of different dimensions. Mean compliance or minimal strain energy is considered for the optimization. Volume fraction is given to the design space to assign appropriate steel material quantities. The purpose of this study is to evaluate optimal shapes of stiffeners with the maximum rigidity that improves the axial and shear performance of the H-beam and to satisfy a given safety design standard of H-beam and stiffeners in case arbitrary load effect and resistances. Finally, the effectiveness of stiffness-based topology optimization on stiffeners is verified with several practical applicable examples.

• Elastomers and Composites
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• v.42 no.4
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• pp.217-223
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• 2007

Thermomechanical and shape memory properties of dicumyl peroxide(DCP) cured semicrystalline EPDM($Nordel^{(R)}$ IP) were investigated. From gel content analysis, it can be seen that Nordel can be crosslinked by small amount of DCP and the degree of crosslinking increased with the increase of DCP content. DSC analysis revealed that the melting temperature and degree of crystallinity of the crosslinked rubber decreased with the increase of DCP. Tensile test showed that tensile modulus increased and elongation at break of the rubber decreased with an increase in the degree of cross linking. The chemically crosslinked semi-crystalline EPDM exhibited excellent shape memory behavior, i.e. the sample was easily deformed to have an arbitrary secondary shape above its melting temperature and was fixed well in its deformed state when it is cooled, and then the fixed shape was recovered to its original shape very fast upon heating above its melting temperature.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.2
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• pp.96-106
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• 2002

In this paper, we propose a new image-watermarking scheme lot arbitrarily shaped object based on Polar coordinates Shape Adaptive Discrete Transform (PSADT). Using log-polar coordinates conversion and shape adaptive discrete transform, the proposed watermarking method can be applied to any arbitrarily shaped image-object such as MPEG-4 VOP and is much more robust to geometrical attacks such as rotation and scaling than the conventional methods.

• Explosives and Blasting
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• v.39 no.1
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• pp.1-9
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• 2021

As the national economic growth and the rapid increase in industrial structures are aging, the demand for removing steel structures is increasing, and research on improving the penetration performance of the linear shape charge explosives. In the study, numerical analyses were performed on the effect of the type of explosive used in the self-made shape charging container and the initiation method on the cutting performance of the steel plate and the effect on the shaped explosive installed close to it. ANSYS LS-DYNA, which can analyze the large deformation problem of materials due to explosion, was used, and an ALE(Arbitrary-Lagrange-Eulerian) model was applied that enables interlocking analysis of gases, liquids, and solid.