• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.133-138
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• 2005

The deformation of sheet metal due to the residual stress during blanking or piercing process, is numerically simulated by means of a commercial finite element code. Two dimensional plain strain problem is solved and then its result is applied to the deformation analysis of the lead frame. The plain strain element is applied to the 2D problem to observe the Von Mises equivalent stress concentration at the both shearing edges. As the punch penetrates into the sheet material, the stress concentration generated on both edges is getting increased to be the shearing surface. The limits of the punching depth applied to the simulation is 16% and 24% of the sheet thickness for the plain strain element and the hexahedral element, respectively. The hexahedral element and the limit of punching depth were applied to the deformation analysis of the lead frame for the blanking process. The FEM results for the lead deformation were very good agreement with the experimental ones. This paper shows that the coarse mesh has enabled to analyze the lead deformation generated due to the blanking mechanism. This simple approach to save the calculation time will be very effective to the design of the blanking tools in industries.

• Geophysics and Geophysical Exploration
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• v.10 no.2
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• pp.154-160
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• 2007

This paper compares the characteristics of three different algorithms for three-dimensional (3D) magnetotelluric (MT) modeling. These methods are developed by Mackie et al. (1994), Sasaki (1999) and Nam et al. (2007). The first and second methods are based on the finite difference method (FDM), while the last one the finite-element method (FEM). MT responses, apparent resistivities and phases, for a COMMEMI 3D-2 model show a good agreement with integral equation solutions and only minor discrepancies are found over the anomalous bodies in the 3D model. The computation time of the two methods based on FDM is short and the static divergence correction contributes to speed up. The FEM modeling scheme is accurate but slow.

• Journal of Advanced Research in Ocean Engineering
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• v.1 no.2
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• pp.115-133
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• 2015

This paper describes an approach for the numerical analysis of container ship slamming and whipping and various parameters that influence slamming and whipping. For validation purposes, the numerical analysis results were compared with experimental results obtained as part of the Wave-Induced Loads on Ships Joint Industry Project. Water entry problems for two-dimensional (2D) sections were first solved using a 2D generalized Wagner model (GWM) for various drop conditions and geometries. As the next step, the hydroelastic numerical analysis of a 10,000-TEU container ship subjected to slamming and whipping loads in waves was performed. The analysis method used is based on a fully coupled model consisting of a three-dimensional (3D) Rankine panel model, a 3D finite element model (FEM), and a 2D GWM, which are strongly coupled in the time domain. Parametric studies were carried out in both numerical and experimental tests with various forward speeds, wave heights, and wave periods. The trends observed and the validity of the numerical analysis results are discussed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.3
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• pp.93-100
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• 2003

Switched reluctance motor(SRM) has some advantages such as low cost, high torque density but SRM has essentially high torque ripple due to its salient structure. In order to apply SRM to industrial field, torque ripple has to be reduced. This paper introduces optimal design process of SRM using an optimization algorithm of Progressive Quadratic Response Surface Modeling(PQRSM) and two-dimensional(2D) Finite Element Method(FEM). The electrical and geometrical design parameters have been adopted as 2D design variables. From this work, it can be obtained both the optimal design minimized torque ripple and the optima1 design maximized the average torque, respectively. Finally, this Paper Presents Performance comparison of two optimal designs and consider influence of the selected design variables in torque characteristics.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1639-1647
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• 2016

This paper deals with eddy current loss analysis of Slotless Double sided Cored type permanent magnet linear generator by using analytical method, space harmonic method. In order to calculate eddy current, this paper derives analytical solution by the Maxwell equation, magnetic vector potential, Faraday's law and a two-dimensional(2-D) cartesian coordinate system. First, we derived the armature reaction field distribution produced by armature wingding current. Second, by using derived armature reaction field solution, the analytical solution for eddy current density distribution are also obtained. Finally, the analytical solution for eddy current loss induced in permanent magnets(PMs) are derived by using equivalent, electrical resistance calculated from PMs volume and eddy current density distribution solution. The analytical result from space harmonic method are validated extensively by comparing with finite element method(FEM).

• Structural Engineering and Mechanics
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• v.66 no.1
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• pp.85-96
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• 2018

This study investigates the response of functionally graded (FG) gas pipe under unsteady internal pressure and temperature. The pipe is proposed to be manufactured from FGMs rather than custom carbon steel, to reduce the erosion, corrosion, pressure surge and temperature variation effects caused by conveying of gases. The distribution of material graduations are obeying power and sigmoidal functions varying with the pipe thickness. The sigmoidal distribution is proposed for the 1st time in analysis of FG pipe structure. A Two-dimensional (2D) plane strain problem is proposed to model the pipe cross-section. The Fourier law is applied to describe the heat flux and temperature variation through the pipe thickness. The time variation of internal pressure is described by using exponential-harmonic function. The proposed problem is solved numerically by a two-dimensional (2D) plane strain finite element ABAQUS software. Nine-node isoparametric element is selected. The proposed model is verified with published results. The effects of material graduation, material function, temperature and internal pressures on the response of FG gas pipe are investigated. The coupled temperature and displacement FEM solution is used to find a solution for the stress displacement and temperature fields simultaneously because the thermal and mechanical solutions affected greatly by each other. The obtained results present the applicability of alternative FGM materials rather than classical A106Gr.B steel. According to proposed model and numerical results, the FGM pipe is more effective in natural gas application, especially in eliminating the corrosion, erosion and reduction of stresses.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.21-23
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• 2007

It is well known that the characteristics of the induction machine depend on a great degree on the leakage reactance. And the leakage reactance is different according to a level of slant. So in this paper, we calculated the inductance per coil side. And the torque and speed characteristics are analyzed using a method base on the two-dimensional (2-D) finite element method (FEM) and on the circuits theory to model the rotor bar in a induction machine. The variable values of bar angle of slant are considered.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.140-142
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• 2006

Cogging torque is often a principal source of vibration, noise and difficulty of control in permanent-magnet brushless DC motors. Cogging torque can be minimized by sinusoidal air-gap flux density waveform because it is produced by the interaction of the rotor magnetic flux and angular variation in the stator magnetic reluctance. Therefore, this paper will present a design method of magnetization system of bonded isotropic neodynium-iron-boron(Nd-Fe-B) magnets in ring type with sinusoidal air-gap flux density distribution and low manufacturing cost. An analytical technique of magnetization makes use of two-dimensional finite element method(2D FEM) and Preisach model that expresses the hysteresis phenomenon of magnetic materials in order for accurate calculation.

• Journal of Magnetics
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• v.18 no.3
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• pp.297-301
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• 2013

Flux-reversal machine (FRM) is cost effective and suitable for mass production due to its simple structure. However, there is a notable permanent magnet flux leakage which deteriorates the performance. To compensate this drawback with a design method, an Inset-Permanent-Magnet-Type FRM (ITFRM) has been proposed. The ITFRM has permanent magnets perpendicular to the stator teeth surface, and thus, is much more difficult to demagnetize. In this paper, we deal with the iron losses and irreversible permanent magnet demagnetization characteristics of the ITFRM according to various design variables and driving conditions. To analyze the characteristics, a two-dimensional finite-element method (2D-FEM) considering nonlinear analysis of permanent magnets is used. As a result, we propose the design variables that have the largest effects on the iron losses and irreversible magnet demagnetization.

• Geophysics and Geophysical Exploration
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• v.3 no.2
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• pp.48-52
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• 2000

We have calculated and analyzed the electromagnetic responses of buried conductive pipes due to a horizontal magnetic dipole source on the pound using a three-dimensional (3-D) finite element method to provide useful guidelines for designing electromagnetic pipe locator and for field operation of the system. For single buried pipe, the horizontal component and the horizontal difference of the vertical component of magnetic field show peaks above the pipe. When comparing the width of response curves of both cases around the peak, horizontal difference of vertical component of magnetic field shows much narrower peak, 2 times narrower at a half of maximum amplitude, than that of horizontal component of magnetic field. Accordingly, we can pinpoint the horizontal location of pipe on the ground more accurately by measuring the horizontal difference of vertical component of magnetic fold. Moreover, it will have a merit in determining the depth of pipe, because the equation for depth estimation is defined just above the pipe. When there are two buried pipes separated by two meters with each other, the response of horizontal difference of vertical component of magnetic field has two separate peaks each of which is located above the pipe whereas horizontal magnetic field response has only one peak above the pipe just below the transmitter. Thus, when there exist more than a buried pipe, measuring the horizontal difference of vertical magnetic field can effectively detect not only the pipe under transmitter but also adjacent ones. The width of response curves also indicates higher resolving ability of horizontal difference of vertical component of magnetic field.