• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.97-105
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• 2000

One of the most important steps to determine the blank shape and dimensions in deep drawing process is to calculate the surface area of the product. In general, the surface area of axisymmetric products is calculated by mathematical or graphical methods. However, in the case of non-axisymmetric products, it is difficult to calculate the exact surface area due to errors as separated components. Fortunately, it is possible for elliptical products to recognize the geometry of the product in the long side and short side by drafting in another two layers on AutoCAD software. So, in this study, a surface area calculating system is constructed for a design of blank shape of deep drawing products. This system consists of input geometry recognition module and three dimensional modeling module, respectively. The suitability of this system is verified by applying to a real deep drawing product. The system constructed in this study would be very useful to reduce lead time and cost for determining the blank shape and dimensions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.753-756
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• 2000

The accumulated know-how and trial-and-error procedures are known as the best ways to determine blank shape and dimensions. One of the most important steps to determine the blank shape and dimensions in deep drawing process is to calculate the surface area of the product. In general, the surface area of products is calculated by mathematical or 3-D modeling methods. A blank design system is constructed for elliptical deep drawing products to recognize the geometry of the product in the long side and short side by drafting in another two layers on AutoCAD software. This system consists of input geometry recognition module, 3-D modeling module and blank design module, respectively. Blank dimension of three types is determined by the same area, which was acquired in 3-D modeling module. The suitability of this system is verified by applying to a real deep drawing product.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.3
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• pp.255-260
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• 2002

This paper describes a fuzzy-based system for analyzing the stress intensity factors (SIFs) of three-dimensional (3D) cracks. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-coded quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. The singular elements such that the mid-point nodes near crack front are shifted at the quarter-points, and these are automatically placed along the 3D crack front. The complete finite element(FE) model is generated, and a stress analysis is performed. The SIFs are calculated using the displacement extrapolation method. To demonstrate practical performances of the present system, semi-elliptical surface cracks in a inhomogeneous plate subjected to uniform tension are solved.

• Ocean Systems Engineering
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• v.14 no.3
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• pp.261-276
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• 2024

Numerical investigation was carried out to analyze the hydrodynamic response of 4-column semi-submersible floaters, incorporating variations such as stepping and alterations in the shape/geometry of columns and pontoons, as well as tilting of main columns. Utilizing Ansys-AQWA, a hydrodynamic software based on panel method, simulations were executed for these scenarios. The simulations yielded insights into responses, excitation forces/moments, and pressure on the structure, facilitating a comparison between the models through a parametric study. It was observed that stepping of pontoons and tilting of columns led to reduced responses, forces, and pressures, reaching balance through appropriate stepping and tilting. Additionally, altering the geometry of columns and pontoons indicated the potential benefits of employing elliptical pontoons and pentagonal columns for enhanced response control.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.952-959
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• 2006

In this paper, 2-D RAKE receiver simulator is made which beamforming technique is applied to in WCI)MA uplink basestation, and the performance is compared with that of 1-D RAKE receiver with varying the number of array elements, RAKE fingers and users. To model angular component of received signal and interfering signals due to multiple access, it is assumed that multiple users are located in the arbitrary direction of the same distance far from the basestation within a sector of the cell, and the channel simulator is made by using Geometry Based Single Bounce Elliptical Model(GBSBEM) suggested by Rappaport. BER performance is compared and analyzed with the various choise of the number of array elements, the number of RAKE fingers, the number of users and Eb/No. These results indicate that increasing the number of array elements eliminates efficiently multiple access interfering signals and improves dramatically BER performance.

• Journal of The Korean Astronomical Society
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• v.49 no.5
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• pp.193-198
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• 2016

Early-type galaxies (ETGs) are supposed to follow the virial relation $M=k_e{\sigma}^2R_e/G$, with M being the mass, σ_* being the stellar velocity dispersion, R_e being the effective radius, G being Newton's constant, and k_e being the virial factor, a geometry factor of order unity. Applying this relation to (a) the ATLAS^3D sample of Cappellari et al. (2013) and (b) the sample of Saglia et al. (2016) gives ensemble-averaged factors 〈k_e〉 = 5.15 ± 0.09 and 〈k_e〉 = 4.01 ± 0.18, respectively, with the difference arising from different definitions of effective velocity dispersions. The two datasets reveal a statistically significant tilt of the empirical relation relative to the theoretical virial relation such that $M{\propto}({\sigma}^2_*R_e)^{0.92}$. This tilt disappears when replacing R_e with the semi-major axis of the projected half-light ellipse, a. All best-fit scaling relations show zero intrinsic scatter, implying that the mass plane of ETGs is fully determined by the virial relation. Whenever a comparison is possible, my results are consistent with, and confirm, the results by Cappellari et al. (2013). The difference between the relations using either a or R_e arises from a known lack of highly elliptical high-mass galaxies; this leads to a scaling (1 - ϵ ) ∝ M^0.12, with ϵ being the ellipticity and $R_e=a\sqrt[]{1-{\epsilon}}$. Accordingly, a, not R_e, is the correct proxy for the scale radius of ETGs. By geometry, this implies that early-type galaxies are axisymmetric and oblate in general, in agreement with published results from modeling based on kinematics and light distributions.

• Journal of Digital Convergence
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• v.14 no.8
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• pp.555-564
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• 2016

Space perception is generally treated as a problem relevant to the ability to recognize objects. Alternatively, the data from shape perception studies contributes to discussions about the geometry of visual space. This geometry is generally acknowledged not to be Euclidian, but instead, elliptical, hyperbolic or affine, which is to say, something that admits the distortions found in so many shape perception studies. The purpose of this review article is to understand perceived shape and the geometry of visual space in the context of visually guided action. Thus, two prominent approaches that explain the relation between perception and action were compared. It is important to understand the fundamental information of how human perceive visual space and perform visually guided action for the convergence on embodied cognition, and further on artificial intelligence researches.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.144-155
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• 2000

초록 The validity, of a single parameter such as stress intensity, factor K or J-integral in traditional fracture mechanics depends strongly on the geometry, and loading condition. Therefore the second parameter like T-stress measuring the stress constraint is additionally needed to characterize the general crack-tip fields. While many, research works have been done to verify, the J-T description of elastic-plastic crack-tip stress fields in plane strain specimens, limited works (especially. for bimaterials) have been performed to describe the structural surface crack-front stress fields with the two parameters. On this background, via detailed three dimensional finite element analyses for surface-cracked plates and straight pipes of homogeneous materials and bimaterials under various loadings, we investigate the extended validity or limitation of the two parameter approach. We here first develop a full 3D mesh generating program for semi-elliptical surface cracks, and calculate elastic T-stress from the obtained finite element stress field. Comparing the J-T predictions to the elastic-plastic stresses from 3D finite element analyses. we then confirm the extended validity of fracture mechanics methodology based on the J-T two parameters in characterizing the surface crack-front fields of welded plates and pipes under various loadings.

• International Journal of High-Rise Buildings
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• v.7 no.4
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• pp.313-325
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• 2018

Concrete-filled steel tubular (CFST) members are commonly used as composite columns in modern construction. However, the current guidelines for members' fire design (EN1994-1-2) have been proved to be unsafe in case the relative slenderness is higher than 0.5. In addition, the simplified design methods of Eurocode 4 are limited to circular and square CFST columns, while in practice columns with rectangular and elliptical hollow sections are being increasingly used because of their architectural aesthetics. In the last years a large experimental research has been carried out at Coimbra University on the topic. They have been tested concrete filled circular, square, rectangular and elliptical hollow columns with restrained thermal elongation. Some parameters such as the slenderness, the type of cross-section geometry as well as the axial and rotational restraint of the surrounding structure to the column have been tested in order to evaluate their influence on the fire resistance of such columns. In this paper it is evaluated the influence of the boundary conditions (pin-ended and semi-rigid end-support conditions) on the behavior of the columns in case of fire. In these tests it could not be seen a marked effect of the tested boundary conditions but it is believed that the increasing of rotational stiffness increases the fire resistance of the columns.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1127-1134
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• 2002

The present paper provides an engineering J estimation equation for surface cracked plates under combined bending and tension. The proposed equation is based on the reference stress approach, and the most relevant normalising loads to define the reference stress for accurate J estimations are given for surface cracked plates under combined bending and tension. Comparisons with J results from extensive 3-D FE analyses, covering a wide range of crack geometry, plate geometry and loading combination, show overall good agreement not only at the deepest point but also at arbitrary points along the crack front. for pure tension, agreement between the estimated J and the FE results is excellent, even at the surface point. On the other hand, for pure bending and combined bending and tension, the estimated J values become less accurate for locations close to the surface point. Thus the results in this paper will be useful to assess short-term fracture or low cycle fatigue of surface defects in plates under combined bending and tension.