• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.154-161
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• 2005

In the machine tool industry, direct drive linear motor technology is an interesting means to achieve high acceleration, and to increase reliability. This paper analyzes and compares the characteristics of a tubular linear motor with Halbach and radial magnet array, respectively. First, the governing equations are established analytically in terms of the magnetic vector potential and two dimensional cylindrical coordinate systems. Then, we derive magnetic field solutions due to the PMs and the currents. Motor thrust, flux linkage and back emf are also derived. The results are shown to be in good conformity with those obtained from the commonly used finite element method. Finally, control parameters are obtained from analytical solutions.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.1
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• pp.127-133
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• 2000

A numerical study of the flow of incompressible fluid in a polar cavity is presented. Irregular grids is proposed by applying the interior division principle to the variables on polar coordinate grid formation. Stability analysis and the pressure correction method of SOLA algorithms were discussed in detail on cylindrical coordinates. The results present that unsteady flow behavior appears over $Re=3{\times}10^4$ on polar cavities but nearly steady state at $Re=10^4$. Furthermore, with increasing Reynolds numbers, vortices behaviors indicate more complicated flow phenomena and more severe temporal fluctuation of total kinetic energy and time variation of velocity components at arbitrary pick-up points are detected in case of $Re=5{\times}10^4$.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.612-614
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• 1992

This paper presents the analysis method of TLIM, for the purpose of developing linear induction motor drive for elevators. The transfer matrix to multilayer on cylindrical coordinate is derived. The equivalent circuit constructed from coupling complex phasor makes it possible to obtain characteristics of TLIM. The validity of the method lo verified by comparing the experimental and theoretical results for a pilot machine in locked status.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.712_713
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• 2009

This paper deals with the analysis on eddy current looses of high speed permanent magnet synchronous motor (PMSM) for turbo compressor according to voltage source driving. This paper presents analytical procedures for calculation of the eddy current losses using Poynting theorem. On the basis of the magnetic vector potential and a two-dimensional (2-D) cylindrical coordinate system, this paper derived analytical solutions of the eddy current looses using phase current analysis. The eddy current losses of each harmonic obtained by fast Fourier transform (FFT) analysis of phase current are with results obtained from finite-element method (FEM).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.11
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• pp.2954-2965
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• 1996

In this paper, the electromagnetic field characteristics of leaky caxial cable are anlyzed by using the finite difference-time domain(FDTD) technique. Finite difference equations of Maxwell's equations are definedin cylindrical coordinate systems. To simulate the open boundary problem like a free space, the Mur's Absorbing Boundary condition(Mur-ABC) is also used. After modeling the leaky coaxial cable with the three dimensional grid structure, the transient response of the field distribution and the current distribution, the field pattern, the coupling effect are depicted in the time domain.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.94-101
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• 1996

The purpose of this paper is to analyze the field distribution and the current distribution of leaky coaxial cable with the finite difference-tiem domain(FDTD) algorithm. finite difference equations of maxwell's equations are defined in cylindrical coordinate systems. To simulate the unbounded problem like a free space, the Mur's absorbing boundary conditon is also used. After modeling the leaky coaxial cable with the three dimensional grid structure, the transient resoponse of th efield distribution and the current distribution are depicted in the time domain.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.745-750
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• 2000

A numerical code which can simulate unsteady, incompressible and 3-dimensional flows in an engine cylinder has been developed. The governing equations based on the cylindrical coordinate are discretized by the finite volume method with staggered variable arrangements. A geometric conservation rule is also incorporated into the simulation code in order to deal with a moving boundary problem. For the unsteady simulation, a fractional step method is adopted. The law of wall is applied to the wall boundaries and standard $k-\;{\varepsilon}$ model is used to describe the in-cylinder turbulent flow. The model cylinder has one eccentric port, flat piston and flat cylinder-head. The comparisons with experimental data show fairly well qualitative agreement.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.5
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• pp.137-144
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• 1998

A mathematical model for investigating the form generation mechanism in the centerless thrufeed grinding process is described. The length of the contact line and the magnitude of the grinding force between the grinding wheel and workpieces vary with the change of the axial location of the current workpiece during grinding. Thus, a new coordinate system and a grinding force curve of previous and/or following workpieces are introduced to treat the axial motion. Experiments and computer simulations were carried out using three types of cylindrical workpiece shapes. To validate this model. simulation results are compared with the experimental results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.813-824
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• 1988

Use of a plasma arc as the source of energy for penetration welding of thin plates gives rise to a cylindrical hole surrounded by the molten metal. Material moves from the front to the rear of the hole by flowing around the hole as the workpiece is translated relatively to the arc. Based on the finite difference method, three different computer models have been proposed for the steady state, two dimensional heat and mass flow during the plasma arc welding. In the formulation energy equation was derived by the energy blance method through the cell control volume, and all the governing equations derived for the fixed coordinates was translated for the moving coordinate system. The driving force for fluid flow being considered was only electromagnetic force. The calculated and measured molten poon and HAZ width were compared and better agreement was obtained for the models considering the keyhole effect.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.794-795
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• 2015

This paper deals with back-EMF characteristic comparison of Vertical and Halbach array double-sided linear generator with coreless type. On the basis of a magnetic vector potential and Maxwell's equations, governing equations are obtained, and magnetic modeling is predicting characteristic analysis by using the Fourier series expansion. And then, we obtained magnetic field solutions and calculated resistance, back-EMF constant. The analytical results used by 2-D cylindrical coordinate system. The analytical method used in this paper is confirmed by comparing with finite element analysis results.