• Transactions of Materials Processing
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• v.20 no.6
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• pp.439-449
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• 2011

The temperature distribution and subsequent permanent deformation of SS400 carbon steel plate subjected to an induction-based line heating process were studied by a numerical method involving coupled 3-D electromagnetic-thermal-structural analysis. The numerical study revealed that the amount of permanent deformation is strongly related to the Joule loss caused by such process conditions as input power and moving speed of the heat source. To validate the numerical analysis results, line heating experiments were carried out with a high frequency(HF) induction heating(IH) equipment capable of bending thick plate with the moving accuracy of ${\pm}0.1mm$ in heating coil position. The amount of permanent deformation increased with decreasing moving speed and increasing input power.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.118-123
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• 2018

Coil guns are known worldwide as inexpensive space launch vehicles. The principle of Fleming's right-hand rule allows the coil gun to accelerate the projectile by applying enormous voltage to the solenoid coil. This study was performed to improve the speed of the coil gun using MATLAB, a commercially available numerical program for high launching force of electromagnetic projectiles. To maximize the speed of the projectile, the largest coil of American wire gauge was used, and the number of windings in the radial and axial directions of the solenoid coil was optimized. Optimal length of the projectile was obtained by calculating the optimal aspect ratio between the axial length of the solenoid coil and the length of the projectile.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.95-98
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• 2000

Film bulk acoustic resonator used in microwave region can be analyzed by one-dimension Mason's model and one-dimensional numerical method, but it had several constraints to analyze effects of area variation, electrode-area variation, electrode-shape variation and spurious characteristics. To overcome these constraints film bulk acoustic resonator must be analysed by three dimensional numerical method. So, in this paper three dimensional finite element method was used to analyze several moles of resonance and was compared with the one dimension Mason's model analysis and analytic solution.

• Journal of computational fluids engineering
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• v.4 no.2
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• pp.31-38
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• 1999

Numerical analysis is conducted on the deformation of free surface of magnetic fluid. Steady magnetic fields are induced by a circular current loop. Governing equations of magnetic fields are solved by using the concept of vector potential. The free surface of magnetic fluid is formed by the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body force. The deformations of free surface of magnetic fluid are qualitatively clarified. And, the patterns of steady non-uniform magnetic fields induced by a circular current loop are quantitatively presented. The shape of free surface attained by the polar fluid approach is rougher and higher than that attained by the quasi-steady approach.

• Journal of Electrical Engineering and Technology
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• v.8 no.2
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• pp.331-338
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• 2013

A new reliability calculation method is proposed based on design sensitivity analysis by the finite element method for nonlinear performance constraints in the optimal design of electromagnetic devices. In the proposed method, the reliability of a given design is calculated by using the Monte Carlo simulation (MCS) method after approximating a constraint function to a linear one in the confidence interval with the help of its sensitivity information. The validity and numerical efficiency of the proposed sensitivity-assisted MCS method are investigated by comparing its numerical results with those obtained by using the conventional MCS method and the first-order reliability method for analytic functions and the TEAM Workshop Problem 22.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.5
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• pp.282-288
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• 1988

A Multi-grid method is introduced to Finite Element Analysis of electromagnetic field problems in order to reduce the computational time. The puropse of this work is to study how to intermix discretization and solving process, thereby making the process more effective and to find the optimal factors of Multi-grid method. Several numerical experiments with linear models of uniform and nonuniform grids confirm that the proposed algorithm can reduce the computational time very effectively as compared with con ventional iterative methods. The best results are obtained with V cycle and S.O.R. with the acce leration factor of 1.3-1.4 for smoothing.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.766-773
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• 1999

A numerical analysis has been performed solidification problem using the fixed grid-enthalpy method with enthalpy-porosity relation. A modified standard $k-\varepsilon$ model was applied to describe the influence of turbulent flow. Computational procedures are based on the finite volume method and the non-staggered grid system. Comparisons with the different three experimental results show that applying a modified standard $k-\varepsilon$model in mushyzone is better than the previous computation results. This paper includes another EMBR's influences such as change of velocity field, Increasement of temperature and dispersion of flow out of nozzle into the flow field. These EMBR's influences are compared to case without EMBR.

• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.129-135
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• 2007

In this paper, we present a set of numerical schemes to solve the Muller integral equation for the analysis of electromagnetic scattering from arbitrarily shaped three-dimensional (3-D) dielectric bodies by applying the method of moments (MoM). The piecewise homogeneous dielectric structure is approximated by planar triangular patches. A set of the RWG (Rao, Wilton, Glisson) functions is used for expansion of the equivalent electric and magnetic current densities and a combination of the RWG function and its orthogonal component is used for testing. The objective of this paper is to illustrate that only some testing procedures for the Muller integral equation yield a valid solution even at a frequency corresponding to an internal resonance of the structure. Numerical results for a dielectric sphere are presented and compared with solutions obtained using other formulations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4156-4162
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• 2013

This study was peformed to determine optimum induction heating conditions for a round bar of crankshaft. Four induction heating conditions were proposed and evaluated, employing numerical method, based on electromagnetic and sequential heat transfer analyses, resulting in optimum induction heating conditions which are finally proposed based on peak temperatures at heating zone and minimum temperature gradient through thickness of a round bar after 1 hour induction heating.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.88-93
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• 2008

The electromagnetic parameters of a permanent magnet synchronous motor (PMSM) such as the open load permanent magnet flux, d axis reactance $X_d$, and q axis reactance $X_q$, are most essential to the performance analysis and optimization design of the motor. Based on the numerical analysis of the 3D electromagnetic field, the three electromagnetic parameters of permanent magnet synchronous motors with U form interior rotor structures are calculated by FEA. The rules of the leakage coefficient and reactance parameters changing with the air gap length, permanent magnet magnetism length, and isolation magnetic bridge dimensions in the rotor are given. The calculated values agree well with the measured values. The FEA results are integrated with the self compiled electromagnetic design program to optimize the prototype motor. The tested performances of the prototype motor prove that the method is suitable for the optimization of motor structure.