• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.5
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• pp.705-709
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• 2010

It is quite complex to draw the geometry of electron trajectories in electron optics because such trajectories have various aberrations that cannot be easily calculated. However, if we need to know roughly the geometry, the focal length and the principal planes in order to understand the properties of column, a simple numerical solution can be a useful method. We are developing the electron beam machining system based on SEM. In this paper, we show rough geometry, focal length and principal planes by a numerical solution for electron lens I in our column. These results will be utilized in developing a simulation program for electron optics.

• Journal of computational fluids engineering
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• v.2 no.2
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• pp.97-103
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• 1997

A modified Delaunay triangulation technique is tested for complicated computational domain. While a simple geometry. both in topology and geometry, has been well discretized into triangular elements, a complex geometry having difficulty in triangulation had to be divided into small sub-domains of simpler shape. The present study presents a modified Delaunay triangulation method based on the data structure of geometric modeller. This approach greatly enhances the reliability of triangulation, especially in complicated computational domain. We have shown that efficiency of Delaunay triangulation can be much improved by using both the GUI (Graphic User Interface) and OOP (Object-Oriented Programming).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.869-872
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• 2003

This paper presents a geometric machining simulation algorithm to enhance the reliability and user-friendliness of a comprehensive computer aided process planning (CAPP) system by verifying generated NC data. In order to represent the complex machining geometry with high accuracy, the proposed algorithm is developed based on a boundary representative (B-rep) solid modelling kernel. Solid models are used to represent the part geometry. tool swept volume and material removal volume by Boolean unite and subtract operations. By integrating a machining simulation procedure into the CAPP system, the systematic analysis of the tool path can be implemented synthetically. To demonstrate and check the validity of suggested system, a simple example of simulation is represented and the result is discussed.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.2
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• pp.114-120
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• 2004

Propeller blades have complex airfoil section type geometry and the thickness is continuously varied to both its length and cord-wise direction. in the present research, the finite element analysis program PROSTEC (Propeller Stress Evaluation Code) is developed to calculate the structural responses of propeller blades in irregular ship wake field. To represent the curved and skewed geometry of propeller blades accurately, 20-node curved solid element using the quadratic shape function is adopted. Input data for the analysis including the geometry and pressure distribution of propeller blades can be generated automatically from the propeller design program. And to visualize the results of analysis on windows system conveniently, the post processor PROSTEC-POST is developed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.55-61
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• 2007

The hypoid gear has advantage for the high reduction ratio and compactness. But, geometry design and strength evaluation of the hypoid gear depend on the machine tool of specific production companies because the geometry design and strength evaluation of the hypoid gear are complex and difficult. This paper proposes the development of the design programs to satisfying the geometry and strength of a hypoid gear through optimization technique using the genetic algorithm. The genetic algorithm is designed to optimize a method for minimizing volume. The existing design of hypoid gear in the forklift truck axle is compared with the results of developed optimum design program.

• Korean Institute of Interior Design Journal
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• no.37
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• pp.12-20
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• 2003

The purpose of this study is to propose a new design principles and to analyze the pattern of art and architecture applying fractal concepts. As this study is based on fractal geometry as a natural science, 1 intented to explain the concepts and provide some methods of generating fractal properties. Two major aspects are discussed. Frist, fractals are geometric shapes that are self-similar, in other words, they iterate a basic shape at ever increasing a decreasing dimensions. Self-similarity, irregularity, and scaling are fundamental characteristics of fractal geometry. Second, the fractal concepts of art and design can be analyzed and used as a critical tool. In both criticism and design, fractals provides a tool In fine, fractal geometry can be provided endless possibilities for artists and designers intended in expressing the more complex underlying rhythms and organic patterns of nature.

• Bulletin of the Korean Chemical Society
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• v.15 no.8
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• pp.658-662
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• 1994

Ab initio and extended Huckel calculations have been applied to discuss the electronic structure, ring inversion barrier, and geometry of the $Cp_2TiS_3$ compound. The deformation of four membered ring in the planar geometry is originated from a second-order Jahn-Teller distortion due to the small energy gap between HOMO and LUMO on the basis of extended Huckel calculations. The puckered $C_s$ geometry is stabilized by the interaction of the $x^2-y^2$ metal orbital with the hybrid orbital in sulfur. Ab initio calculations have been carried out to explore the ring inversion process for the model $Cl_2TiS_3$ compound. We have optimized $C_s$ and $C_{2v}$ structures of the model compound at the RHF level. The energy barriers for the ring inversion are sensitive to the used basis set. With 4-31$G^*$ for the Cl and S ligands, the barriers are computed to be 8.41 kcal/mol at MP2 and 8.02 kcal/mol at MP4 level.

• Bulletin of the Korean Chemical Society
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• v.17 no.4
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• pp.331-334
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• 1996

New copper(Ⅱ) complex of the pentaaza non-macrocyclic ligand 1-(2-aminoethyl)-3-(N-{2-aminoethyl}aminomethyl)-1,3-diazacyclohexane (2) and a dinuclear copper(Ⅱ) compex of the bis(macrocyclic) ligand 3, in which two 1,5,8,10,12,15-hexaazabicyclo[11.3.11.5]heptadecane subunits are linked together by an ethylene chain through the uncoordinated nitrogen (N10) atoms, have been prepared selectively by the reaction of the metal ion, 1,4,8-triazaoctane, ethylenediamine, and formaldehyde. The dinuclear complex [Cu2(3)]4+ has been also prepared by the reaction of [Cu(2)]2+ with ethylenediamine and formaldehyde. The reaction products largely depend on the molar ratio of the reactants employed. The mononuclear complex or each macrocyclic subunit of the dinuclear complex contains one 1,3-diazacyclohexane ring and has a square-planar geometry with a 5-6-5 or 5-6-5-6 chelate ring sequence. In acidic solution, the copper(Ⅱ) complex of 2 dissociates more slowly than those of other related non-cyclic polyamines.

• Communications of the Korean Mathematical Society
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• v.35 no.4
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• pp.1255-1267
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• 2020

The class of isotropic almost complex structures, J_𝛿,𝜎, define a class of Riemannian metrics, g_𝛿,𝜎, on the tangent bundle of a Riemannian manifold which are a generalization of the Sasaki metric. This paper characterizes the metrics g_𝛿,0 using the geometry of tangent bundle. As a by-product, some integrability results will be reported for J_𝛿,𝜎.

• Communications of the Korean Mathematical Society
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• v.27 no.2
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• pp.307-315
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• 2012

We study the geometry of real lightlike hypersurfaces of an inde nite Kaehler manifold $\bar{M}$. We provide new results on such a real lightlike hypersurface $M$ by using the $F$-structure of $M$ induced by the almost complex structure $J$ of $\bar{M}$.