• Journal of the Korean Society for Precision Engineering
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• v.14 no.4
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• pp.145-150
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• 1997

A computer-aided process design system for axisymmetric deep drawing products has been developed. An approach to the system is based on the knowledge based system. The hypothesized process outline of the deep drawing operations is generated in the geometrical design module of the system. In this paper, the module has been expanded. The rules of process design sechems for complex cup drawings are formulated from handbooks, experimental results and empirical knowhow of the field experts. The input to the system is final sheet-metal objects geometry and the output from the system is process sequence with intermediate objects geometries and process parameters, such as drawing load, blank holding force, clearance and cup-drawing coefficient.

• Advances in materials Research
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• v.5 no.4
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• pp.205-221
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• 2016

In this article, the buckling responses of functionally graded curved (spherical, cylindrical, hyperbolic and elliptical) shell panels under elevated temperature load are investigated numerically using finite element steps. The effective material properties of the functionally graded shell panel are evaluated using Voigt's micromechanical model through the power-law distribution with and without temperature dependent properties. The mathematical model is developed using the higher-order shear deformation theory in conjunction with Green-Lagrange type nonlinear strain to consider large geometrical distortion under thermal load. The efficacy of the proposed model has been checked and the effects of various geometrical and material parameters on the buckling load are analysed in details.

• Journal of Aerospace System Engineering
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• v.10 no.3
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• pp.9-14
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• 2016

Using a multiple regression analysis, a total of 78 low-Reynolds-number airfoils are examined in this paper to clarify the systematic relationships between the geometrical parameters of the airfoils and experimentally-determined aerodynamic coefficients. The results show that the effects of the maximum camber and the maximum thickness regarding the maximum lift and the stalling angle of attack, respectively, are major. The lower-surface flatness of the airfoil is also a crucial geometrical parameter for aerodynamic performance. It is proven here that, generally, the application of the regression equations for an assessment of the aerodynamic performance is relatively acceptable, along with an expectation that the lift-curve slope violates the normality assumption.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.8-11
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• 1996

In one VTR(Video Tape Recorder), two or more heads are used to record or reproduce video signals. To obtain a uniform quality of a VTR, video heads should have similar charcteristics such as geometrical shapes and electro-magnetic performances. This research is aimed to develop a visual inspection system that can measure four geoemtrical parameters;HO, HI, Tw and Cw. To obtain a high realable results, DSP based image board and target based image processing algorithms were used. A series of experiments was performed for one thousands of video heads. From observation of the experimental results, the system is found to show good performance for inspection of video heads.

• Korean Journal of Computational Design and Engineering
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• v.2 no.3
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• pp.186-194
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• 1997

This paper describes new methods to minimize the cutting time in zigzag milling operation of two dimensional polygonal surfaces. Previous works have been focused on mainly experimental approaches by considering some machining parameters such as, spindle speed, depth of cut, cutter traverse rate, cutter diameter, number of teeth, tool wear, life of tool, and so on. However, in this study, we considered two geometrical factors one by one in order to see the effect separately, which are the length of cut and the number of cutter traverse. In an N-sided concave or convex polygon, an algorithm has been developed which minimize the total length of cut. Also, a heuristic approach was used to minimize the number of cutter traverse.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.4
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• pp.28-34
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• 2010

W e performed a geometrical nonlinear dynamic analysis of laminated skew plates made of advanced composite materials (ACM ) based on the first-order shear deformation plate theory (FSDT). The Newmark method and Newton-Raphson iteration are used for the nonlinear dynamic solution. The effects of skew angles and layup sequences on the nonlinear dynamic response for various parameters are studied using a nonlinear dynamic finite element program developed for this study. The several numerical results were in good agreement with those reported by other investigators for square composite and skew plates, and the new results reported in this paper show the significant interactions between the skew angle and layup sequence in the skew laminate. Key observation points are discussed and a brief design guideline is given.

• Bulletin of the Korean Chemical Society
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• v.23 no.4
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• pp.555-562
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• 2002

Isomers based on the RS and EZ geometrical isomerism of the neutral, deprotonated species of HMPAO and their complexes with zinc(Ⅱ) ion have been investigated by semiempirical AM1 optimization method. The Hartree-Fock energies on AM1 geometries o f HMPAO species were calculated with HF/6-31G* methods. Twenty-two isomers of the neutral and twenty isomers of the deprotonated species of HMPAO have been found. The presence of four EE-series isomers of both zinc(Ⅱ) complexes with the neutral and deprotonated HMPAO have been expected and the SREE typical isomer of both types of complexes is the most stable isomer. Energies of complexation of zinc(Ⅱ)/HMPAO isomers with AM1 geometries were calculated by HF/ 6-31G*method. Due to the complexations with zinc(Ⅱ), the structural reorganizations of some isomers of the neutral HMPAO have been occurred. The optimized geometrical parameters of the related conformations have been discussed in terms of their stabilities and existences.

• Current Optics and Photonics
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• v.1 no.4
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• pp.336-343
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• 2017

A wide field-of-view (FOV) image contains more visual information than a conventional image. This study proposes a new type of hyperbolic mirror for wide FOV image acquisition. The proposed mirror consists of a hyperbolic cylindrical section and a bowl-shaped hyperbolic omnidirectional section. Using an imaging system with this mirror, it is possible to achieve a $213.8^{\circ}$ horizontal and a $126.94^{\circ}$ vertical maximum FOV. Parameters of each section of the mirror are designed to be continuous at the junction of the two parts, and the resultant image is seamless. The image-acquisition model is obtained using ray-tracing optics. To rectify the geometrical distortion of the original image due to the mirror, an image-restoration algorithm based on conformal projection is presented in this study. The performance of the proposed imaging system with the hyperbolic mirror and its image-restoration algorithm are verified by experiments.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.91-93
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• 2005

Forming sheet metal by laser-induced thermal stresses (laser forming) has been extensively studied, and the research has focused on two-dimensional geometries using a multi-pass straight line scan. Recently there came out some useful studies or three-dimensional laser forming which is applied to doubly curved shapes. The task of 3D laser forming sheet metal is to determine a set of process parameters such as laser scanning paths, laser power and scanning speed that will make a given shape. New method for laser forming of a doubly curved surface by using geometrical information was proposed and verified by experiments. This method shows good performance in the sense of calculation time and accuracy compared to the inherent strain method.

• Structural Engineering and Mechanics
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• v.75 no.6
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• pp.701-711
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• 2020

This papers studies nonlinear stability and post-buckling behaviors of geometrically imperfect metal foam doubly-curved shells with eccentrically stiffeners resting on elastic foundation. Metal foam is considered as porous material with uniform and non-uniform models. The doubly-curved porous shell is subjected to in-plane compressive loads as well as a transverse pressure leading to post-critical stability in nonlinear regime. The nonlinear governing equations are analytically solved with the help of Airy stress function to obtain the post-buckling load-deflection curves of the geometrically imperfect metal foam doubly-curved shell. Obtained results indicate the significance of porosity distribution, geometrical imperfection, foundation factors, stiffeners and geometrical parameters on post-buckling characteristics of porous doubly-curved shells.