• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1621-1626
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• 2003

This study deals with the heat transfer analysis on phase change optical disc with land/groove recording by means of numerical method. Finite difference time domain(FDTD) method was used to obtain the amount of absorption of light propagating inside disc and finite difference element(FEM) method was used to calculate the temperature distribution. The calculated results present the detailed information of recording characteristics on the phase change optical disc. The temperature profiles are quite different between the land track and the groove track. The recorded mark shape on land track is smaller and more elliptic than that on groove track. It is shown that the thermal problem to the neighboring track takes place due to secondary peaks. It is found that the different write strategy should be applied to land and groove recording, respectively.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.11 no.3
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• pp.9-17
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• 1982

In this paper, temperature distributions in radial fin of hyperbolic profile for steady -state with no heat generation are obtained by one-dimensional analytical method, finite difference method and experiment respectively. Heat flow rate and fin efficiency from the fin model are obtained by analytical method. To compare the exact solutions obtained by theoretical analysis with the results obtained by finite difference method, cylindrical shape is selected. Particularly, equations of finite difference method for cylindrical shape with irregular boundary are rearranged and formulated. Consequently, temperature distributions in radial fin can certify that are similar to exact solutions. From theoretical analysis, the effects according to heat flow rate and fin efficiency are related to variation of parameters which are fin thickness ${\delta}_o$, fin base temperature $T_o$, thermal conductivity K with same basic dimensions and the fleets are studied and compared.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.199-206
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• 2005

Engineers have performed slope stability analyses, including Limit Equilibrium Analysis, Finite Difference Analysis and Finite Element Analysis. Each analysis results in different Factor of Safety(FS) for slopes. The comparison of FS results from these stability analyses has been carried out for various conditions, such as geometry of slopes, dry and fully saturated soils, nail and anchor reinforcements. Standard deviations of FS calculated from various slope analyses are 0.03 to 0.04 and 0.22 to 0.48 for the slopes without and with nail or anchor reinforcement, respectively. Construction of tiered concrete retaining wall in addition to nail or anchor reinforcement increases FS of 12% to 29% for fully saturated soils.

• Journal of Hydrospace Technology
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• v.2 no.2
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• pp.80-87
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• 1996

A creep-buckling analysis is studied for a simply-supported viscoelastic column. The fluid-type four-parameter model is employed because of its general applicability to creep materials. Using the imperfection-based incremental approach, a nonlinear load deflection equation is derived. Safe load and critical (or life) time which characterize the stability of the viscoelastic column are obtained mathematically and interpreted physically. A finite difference algorithm is applied to solve the second-order differential equation of the viscoelastic stress-strain relation. Numerical calculation has been made and discussed far a SUS316 stainless steel column.

• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1773-1778
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• 2006

Steady-state natural convection heat transfer characteristics from cylinders in a multiply-connected bounded region are clarified. A spectral finite difference scheme (spectral decomposition of the system of partial differential equations, semi-implicit time integration) is applied in numerical analysis, with a boundary-fitted conformal coordinate system through a Jacobian elliptic function with a successive transformation to formulate a system of governing equations in terms of a stream function, vorticity and temperature. Multiplicity of the domain is expressed explicitly.

• Journal of the Korean Society of Safety
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• v.10 no.2
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• pp.129-133
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• 1995

A new approach to the analysis of thin. rectangular window giass glass supported on flexible gaskets. and subjected to uniform lateral pressures was evolved. Based on the Von Karman theory of plates and using the finite difference method. a computer program which determines the deflections and stresses in simply supported thin glass plates was developed.

• Journal of Magnetics
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• v.22 no.1
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• pp.104-108
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• 2017

Induction motors have wide applicability in many fields, both in industrial sectors and households, for their advantages of a high efficiency and robust structure. The introduction of power-source-containing harmonics into the induction motor winding lowers its efficiency and increases its temperature, greatly affecting its operation characteristics. In this study, we performed an electromagnetic field analysis using the time-difference finite-element method with the purpose of analyzing the steady-state current characteristics of an induction motor. Additionally, we calculated the steady-state current with a method combining an electromagnetic field equation and a circuit equation. In the electromagnetic field analysis, the nonlinearity was taken into account using the Newton-Raphson method, and a backward time-difference method was employed for the time derivative term. Then, we compared the steady-state current of the induction motor obtained by calculation with the experimentally measured values, thus validating the proposed algorithm. Furthermore, we analyzed the impacts of the shape and material of the rotor conductor bar of the induction motor on the steady-state current of the main winding.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.10
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• pp.1005-1011
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• 2011

In this paper, we present a marching-on-in-degree(MOD) finite difference method(FDM) based on the Helmholtz wave equation for analyzing transient electromagnetic responses in a general dispersive media. The two issues related to the finite difference approximation of the time derivatives and the time consuming convolution operations are handled analytically using the properties of the Laguerre functions. The basic idea here is that we fit the transient nature of the fields, the flux densities, the permittivity with a finite sum of orthogonal Laguerre functions. Through this novel approach, not only the time variable can be decoupled analytically from the temporal variations but also the final computational form of the equations is transformed from finite difference time-domain(FDTD) to a finite difference formulation through a Galerkin testing. Representative numerical examples are presented for transient wave propagation in general Debye, Drude, and Lorentz dispersive medium.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.349-356
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• 1999

In general, the term soft ground includes clayey soils, which have large compressibility and small shear resistance due to the external load. All process of consolidation in compressible soils can be explained in terms of a transfer of load from an incompressible pore-water to a compressible soil structure. Therefore, one of the most important subjects about the characteristics of the time-dependent consolidation of the clay foundation by the change of load may be the presumption of the final settlement caused by consolidation and the degree of consolidation according to the time. The problems of discontinuous layer interface are very important in the algorithm and programming for the analysis of multi-layered soils using a numerical analysis, finite difference method. Better results can be obtained by the Process for discontinuous layer interface, since it can help consolidation analysis to model the actual ground. The purpose of this paper Provides an efficient computer algorithm based on numerical analysis using finite difference method(F.D.M.) which account for multi-layered soils to determine the degree of consolidation and excess pore pressures relative to time and positions more realistically.

• Journal of Korean Society of Steel Construction
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• v.12 no.3 s.46
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• pp.303-315
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• 2000

The main object of this study is to analyze mechanical behaviors as anisotropic three-dimensional body under various static loads. This paper presents the applicability of the finite difference method to three dimensional problem of anisotropic body. The finite difference method as applied here is generalized to anisotropic three-dimensional problem of elastic body where the governing differential equations of equilibrium of such bodies are expressed in terms of the displacement u, v, and w in the coordinates axes x, y and z, care being taken to modify the finite difference expressions to satisfy the appropriate boundary conditions. By adopting a new three dimensional finite difference modelling including elimination of pivotal difference points in the case of free boundary condition, the three dimensional problem of anisotropic body was successfully completed. Several numerical results show quick convergence and numerical validity of finite difference technique in three dimensional problem.