• Journal of Electrical Engineering and Technology
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• v.7 no.2
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• pp.184-192
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• 2012

The torque and unbalanced magnetic forces in permanent magnet machines are resultants of the tangential, axial and normal magnetic forces, respectively. Those are in general influenced by pole-teeth-winding configuration. A study of the torque and unbalanced magnetic forces of a small flux concentrating permanent magnet transverse flux machine (FCPM-TFM) in segmented compact structure is presented in this paper. By using FLUX3D software from Cedrat, Maxwell stress tensor has been solved. Finite element (FE-) magneto static study followed by transient analysis has been conducted to investigate the influence of unsymmetrical winding pattern, in respect to the rotor, on the performance of the FCPM-TFM. Calculating the magnetic field components in the air gap has required an introduction of a 2D grid in the middle of the air gap, whereby good estimations of the forces are obtained. In this machine, the axial magnetic forces reveal relatively higher amplitudes compared to the normal forces. Practical results of a prototype motor are demonstrated through the analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.1
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• pp.7-12
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• 2008

The vacuum interrupter (VI) is used for medium-voltage switching circuits due to its abilities and advantages as a compacted environmental friendly circuit breaker. In general, the application of a sufficiently strong axial magnetic field (AMF) permits the arc to be maintained in a diffused mode to a high-current vacuum arc. A full understanding of the vacuum arc physics is very important since it can aid to improve the performance of vacuum interrupter. In order to closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and hydrodynamic fields, simultaneously. In this study, we have investigated the effect of changing geometrical parameters for electromagnetic behaviors of high-current vacuum arcs with two different types of AMP contacts, which are coil-type and cup-type, using a commercial finite element analysis (FEA) package, ANSYS. The present results are compared with those of MAXWELL 3D, a reliable electromagnetic analysis software, for verification.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.1
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• pp.6-11
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• 2004

The single phase switched reluctance motor (SRM) has many merits; simple structure and driving circuits, easy operation and speed control, and etc. This paper presents the torque characteristics of disk type single phase SRM by changing the salient pole lengths and pole arcs. The prototype single phase SRM has a three dimensional magnetic flux pattern because of its structure. That is, the radial and axial magnetic flux contributes to torque generation. Thus, 3D analysis is required for computation of its magnetic field. In this paper, 3D FEM is used for analyzing the magnetic flux distribution and magnetic co-energy.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.1
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• pp.1-10
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• 1996

A numerical study was conducted on the effects of the cusp magnetic field in 8" silicon single crystal grwoth by Czochralski method. For a damping effects simulation by magnetic field, low reynolds number ${\kappa} - {\varepsilon}$ model was adopted. Symmetrci cusp magnetic field has a effect of damping streamline crystal, is lowerd with the increasing cusp magnetic field intensity. The uniformity of the oxygen concentration was improved. The asymmetirc cusp magnetic field increased the oxygen concentration however, oxygen concentration distribution in the radial direction was remained uniform. Suitable combination of symmetric and asymmetric cusp magnetic fields could give uniform and low oxygen concentration in the axial direction.tion.

• Structural Engineering and Mechanics
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• v.24 no.6
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• pp.699-707
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• 2006

In the paper, a direct method of solution of the Navier equation is presented. An orthotropic thick hollow cylinder under a one-dimensional steady-state temperature distribution and a uniform magnetic field with general types of thermal and mechanical boundary conditions is considered. The Navier equation in terms of displacement is derived and solved analytically by the direct method, and magnetothermoelastic responses and perturbation of the magnetic field vector in the orthotropic thick hollow cylinder is described. The present method is suitable for orthotropic thick hollow cylinders placed in an axial magnetic field with arbitrary thermal and mechanical boundary conditions. Finally, numerical examples are carried out and discussed.

• Geophysics and Geophysical Exploration
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• v.23 no.2
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• pp.67-71
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• 2020

In this study, we derive closed-form expressions of magnetic gradient tensor due to a circular cylinder. Because the expression for magnetic field has been derived in a previously conducted study, expressions are developed for the magnetic gradient tensor based on the derivatives of the expressions of magnetic field with respect to the variables of the Cartesian coordinates. Furthermore, expressions are derived for the magnetic gradient tensor based on the relations between the Cartesian and cylindrical coordinates in the derivative because the expression for magnetic field contains variables of cylindrical coordinates owing to its axial symmetry.

• Journal of Magnetics
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• v.22 no.2
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• pp.333-343
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• 2017

A rotating magnetic field (RMF) ${\Phi}_1-{\Phi}_2$ model was developed in consideration of the skin effect. The rotating magnetic field's induced three-dimensional flow was simulated numerically, and the influence of the skin effect was investigated. The rotating magnetic field drives the rotating convection in the azimuthal direction, and a secondary convection appears in the radial-meridional direction. The results indicate that ignoring the skin effect results in a smaller azimuthal velocity component and larger radial and axial velocity components, and that the deviation becomes more obvious with the larger dimensionless shielding parameter K.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.22.2-22.2
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• 2008

Radio and X-ray observations of radio lobes in galaxy clusters indicate large energies stored in the magnetic fields in the radio lobes. These magnetic fields are undoubtedly produced and amplified by the accretion onto the central supermassive black hole. I review recent progress and remaining problems in our understanding of the ways how these magnetic fields can be produced and amplified in the accretion disks and what can be the limiting strength of the magnetic field. The major remaining issue is how ordered magnetic spirals (or jets) can emerge from the turbulent small scale magnetic fields produced by MRI. Another issue is the ratio of the axial to the azimuthal magnetic field in jets.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.949-951
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• 1992

A low pressure DC plasma jet has been used to obtain diamond films from a mixture of $CH_4$ and $H_2$ with high deposition rate (>1$\mu\textrm{m}$/min). The effects of the deposition conditions such as torch geometry, substrate temperature, gas mixing ratio, chamber pressure, axial magnetic field on the diamond film properties such as morphology, purity, uniformity of the film and deposition rate, etc. have been examined with the aid of Scanning Electron Microscopy, X-Ray Diffraction, and Raman Spectroscopy. Both the growth rate and particle size increased rapidly for low methane concentrations but saturated and the morphology changed from octahedral to cubic structure when the concentration exceeded 1.0 %. Higher growth rates (>1.5${\mu}m$/min) can be obtained by applying an axial magnetic field to the DC plasma jet. Diamond obtained from the magnetized plasma jet also shows a sharp peak at 1332.5$cm^{-1}$ in the Raman Spectra and this result implies that higher growth rate with a good quality diamond films can he obtained by applying an external magnetic field to the plasma jet.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.217-218
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• 2015

Two axial flux permanent magnet (AFPM) machines using soft magnetic composite (SMC) and lamination steel are studied. Generally stator cores of AFPM machines are manufactured using SMC because AFPM machines need 3 dimensional core structures. However, SMC cores have very disadvantages in magnetic properties. Especially permeability value is much lower than that of lamination steel, so magnetic field density is also lower. In terms of core losses, SMC cores have much larger loss values than lamination steel cores because SMC core can't be laminated. In this study, AFPM machine was designed using laminated steel, and iron losses in two machines using SMC and laminated steel were studied. Simulations were carried out by a commercial 3-D FEM tool.