• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.404-407
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• 2008

Several ITO-less PDP cell structures are presented to improve luminous efficacy. The ITO-less PDP have been applied recently at actual panel manufacture. The influence of ITO-less PDP cell structure on the discharge characteristics has been investigated by using three-dimensional fluid simulation. The variations of electrode geometry parameters such as gap distance, cross bar length, and hump length are investigated for the optimization of cell design.

• International Journal of Concrete Structures and Materials
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• v.19 no.1E
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• pp.25-32
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• 2007

The fracture energy evaluated from the previous experimental results can be simulated by using the modified singular fracture process zone (S-FPZ) model. The fracture model has two fracture properties of strain energy release rate for crack extension and crack close stress versus crack width relationship $f_{ccs}(w)$ for fracture process zone (FPZ) development. The $f_{ccs}(w)$ relationship is not sensitive to specimen geometry and crack velocity. The fracture energy rate in the FPZ increases linearly with crack extension until the FPZ is fully developed. The fracture criterion of the strain energy release rate depends on specimen geometry and crack velocity as a function of crack extension. The behaviors of micro-cracking, micro-crack localization and full development of the FPZ in concrete can be explained theoretically with the variation of strain energy release rate with crack extension.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.8
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• pp.39-46
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• 2003

Productivity and machining performance can be improved by cutting analysis including cutting force prediction, surface error prediction and machining stability evaluation. In order to perform cutting analysis, cutting force coefficients database have to be constructed. Since cutting force coefficients are dependent on cutting condition in the existing research, a large number of calibration tests are needed to obtain cutting force coefficients, which makes it difficult to build the cutting force coefficients database. This paper proposes a generalized method for constructing the cutting force coefficients database us ins cutting-condition-independent coefficients. The tool geometry and workpiece material were considered as important components for database construction. Cutting force coefficients were calculated and analyzed for various helix and rake angles as well as for several workpiece. Furthermore, the variation of cutting force coefficients according to tool wear was analyzed. Tool wear was found to affect tool geometry, which results in the change of cutting force coefficients.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.281-287
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• 2005

This study investigates the pressure drop and heat transfer characteristics of heat exchanger according to the combination of fin configuration and fin pitch of each row by the similitude experiments with the finned-tube geometry scaled as large as four times Finned-tube heat exchanger has 2 rows, and fin geometry consists of two cases, louver-louver and louver-slit. Fin pitch is varied with three types in each case, 6-6 mm, 8-8 mm and 8-6 mm. Results show that total heat transfer can be occurred evenly at each row by varying the fin pitch of 1st row and 2nd row. Heat transfer rate and pressure drop characteristics change according to the combination for fin geometry and fin pitch.

• Water for future
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• v.19 no.3
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• pp.259-266
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• 1986

A numerical study of the process of wave deformation, such as reflection and transmission coefficients and wave forms with bottom change was carried out by Boundary Element Method using linear elements. It is assumed that the incident wave is normal and oblique to the bottom and the wave may be described by linear theory The accuracy of the computational scheme is investigated by comparing the results of other researchers in the following several cases. (1) Simple and sloping stepped bottom geometry (2) Submerged breakater type bottom geometry (3) Trench type bottom geometry

• Journal of The Korean Astronomical Society
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• v.28 no.2
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• pp.223-243
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• 1995

We describe the implementation of a multi-dimensional numerical code to solve the equations for idea! magnetohydrodynamics (MHD) in cylindrical geometry. It is based on an explicit finite difference scheme on an Eulerian grid, called the Total Variation Diminishing (TVD) scheme, which is a second-order-accurate extension of the Roe-type upwind scheme. Multiple spatial dimensions are treated through a Strang-type operator splitting. Curvature and source terms are included in a way to insure the formal accuracy of the code to be second order. The constraint of a divergence-free magnetic field is enforced exactly by adding a correction, which involves solving a Poisson equation. The Fourier Analysis and Cyclic Reduction (FACR) method is employed to solve it. Results from a set of tests show that the code handles flows in cylindrical geometry successfully and resolves strong shocks within two to four computational cells. The advantages and limitations of the code are discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.91-94
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• 2003

We studied the effect of barrier rib height variation using ray-optics code incorporated with three-dimensional plasma simulation to analyze the effects of cell geometry for varying pressure conditions. The optimal barrier rib height decreased as the Xe partial pressure increased which resulted in due to the formation of local, strong sheath under high Xe partial pressure condition.

• Kyungpook Mathematical Journal
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• v.55 no.3
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• pp.715-730
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• 2015

In this note, we extend the definition of harmonic and biharmonic maps via the variation of energy and bienergy between two Riemannian manifolds. In particular we present some new properties for the generalized stress energy tensor and the divergence of the generalized stress bienergy.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.1
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• pp.65-72
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• 2005

Drilling process is one of the most common, yet complex operations among manufacturing processes. The performance of a drill is largely dependent upon drilling forces, Many researches focused on the effects of drill parameters on drilling forces. In this paper, an effective theoretical model to predict thrust and torque in drilling is presented. Also, with the predicted forces, the stress analysis of the drill tool is performed by the finite element method. The model uses the oblique cutting model for the cutting lips and the orthogonal cutting model for the chisel edge. Thrust and torque are calculated analytically without resorting to any drilling experiment, only by tool geometry, cutting conditions and material properties. The stress analysis is performed by the commercial FEM program ANSYS. The geometric modeling and the mesh generation of a twist drill are performed automatically. From the study, the effects of the variation of the geometric features of the drill and of the cutting conditions of the drilling on the drilling forces and the stress distributions in the tool are calculated analytically, which can be applicable for designing optimal drill geometry and for improving the drilling process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.610-614
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• 1996

Sealing of lubricat-air mixture in the high performance machining conte is one of most the important characteristics to carry out enhanced lubrication. High speed spindle requires non-contact type of sealing mechanism. Evaluating an optimum seal design to minimize leakage is concerned in the aspect of flow control. Effect of geometry and leakage path are evaluated according to variation of sealing geometry, Velocity, pressure, turbulence intensity of profile is calculated to fina more efficient geometry and variables. This offers a methodological way of enhancement seal design for high speed spindle. The working fluid is regarded as two phases that are mixed flow of oil phase and air phase. It is more reasonable to simulate an oil jet or oil mist type high speed spindle lubrication. Turbulence and compressible flow model are used to evaluate a flow characteristic, This paper arranges a geometry of mostly used non-contact type seal and analyzes leakage characteristics to minimize a leakage on the same sealing area.