• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.987-989
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• 2005

Axi-periodic analysis using magnetic vector potential is formulated in time harmonic field and applied to the field analysis for the end region of large turbo generator in this paper. By using axi-periodic analysis, the effect of flux shield, one of the structure placed in the end region of large turbo generator to prevent stator end from thermal damage, is studied, and eddy current loss in the flux shield is estimated for operation conditions. 3D FEA is used for the verification of presented analysis method. Because 3D flux distribution can be calculated with 2D modeling, magnetic field showing 3D distribution can be effectively calculated by axi-periodic analysis comparing with 3D FEA.

• 대한기계학회논문집
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• 제15권6호
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• pp.1872-1885
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• 1991

본 연구에서는 자기장의 상호작용을 고려해야 하며 본 연구에서는 유한요소법 을 이용하여 전자기장 해석을 함으로써 이 문제를 해결하였다. 또한 여기서 계산된 자기압력을 이용하여 피가공재의 동적변형 거동을 유한요소법으로 해석하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.24-26
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• 1997

A new permanent magnet has been suggested the novel permanent magnet array using advanced analytical approaches in 1979 by Klaus Halbach. In this paper, the Halbach array is utilized to compose the field system. The ferro-magnetic materials of the electric machines cause the fatal energy loses in high frequency. But Halbach any enables to make the various field distribution without ferro-magnetic materials. This paper presents the magnetic characteristics are analyzed by the analytical method and FEM in case that the field system is composed of the Halbach array.

• Journal of Power Electronics
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• 제19권3호
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• pp.625-636
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• 2019

This paper proposes an active leakage magnetic field (LMF) suppression scheme, which uses the dual-transmitter (DT) topology, for EV wireless charging systems (EVWCS). The two transmitter coils are coplanar, concentric and driven by separate inverters. The LMF components generated by the three coils cancel each other out to reduce the total field strength. This paper gives a detailed theoretical analysis on the operating principles of the proposed scheme. Finite element analysis is used to simulate the LMF distribution patterns. Experimental results show that when there is no coil misalignment, 97% of the LMF strength can be suppressed in a 1kW prototype. These results also show that the impact on efficiency is small. The trade-off between LMF suppression and efficiency is revealed, and a control strategy to balance these two objectives is presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.768-770
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• 2003

A superconducting synchronous motor has different electromagnetic structure from the conventional machine. With the help of superconductor having much higher operating current density than normal conductor, superconducting motor can eliminate most of iron core filled inside of the conventional machine. This air-cored structure could be analysed and designed theoretically based on 2-dimensional(2-D) magnetic field distribution assuming that the windings are extended infinitely toward the axial direction. However, the actual structure of superconducting motor has the end regions interconnecting the straight parts of the same cross-section with the 2-D model. Therefore, this actual 3-D model has smaller field distribution than the 2-D model. In this paper, we consider the effect of the end regions on the output of a HTS model motor and suggest more accurate design approach through comparison of 2-D and 3-D magnetic field analysis results.

• International Journal of Railway
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• 제3권1호
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• pp.14-18
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• 2010

This paper describes design and characteristic analysis of long primary type linear synchronous motor (LSM) for high speed train system. LSM is designed using loading distribution method and magnetic equivalent circuit. For characteristic analysis of LSM, analytical and numerical methods are applied. Analytical method for solving the magnetic field distribution of the analytic model is based on the Maxwell’s equations. Using the characteristic equation and magnetic equivalent circuit, we analyze the effect of variation of parameters, and then we validate the result by comparing with numerical method by finite element method (FEM). We compare the analytical method with numerical method for analyzing the effect by variable parameters. This result will be useful of design and forecast of performance without FEM.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.248-251
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• 2000

The fabrication and characteristics of HTS race-track type field coil for generators was carried out. Field coils are composed of 3 pancake coils wound by 37-filamental Bi-2223/Ag-alloy tapes. The winding machine is horizontal type. The critical currents (I$_c$) of the superconducting tapes were measured with variation of bending strain and external magnetic fields. I$_c$ of both whole field coils and 3 pancake coils were measured as a function of temperature. At 77K under the self-field, I$_c$ of whole field coils was 12A, while in the case of middle pancake coil, I$_c$ was 15A. The distribution of magnetic field B was obtained, using 3-D FEM. Our simulation showed that maximums of B${\bot}$A in x-y plane were locally distributed in both the upper and the lower coils. In addition, the fabrication processes and the characteristics of field coil are described.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1536-1540
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• 1996

The Design of are quenching parts of molded case circuit breakers depends on the utilization of strength and distribution of the magnetic field by which the arc is forced. The magnetic field causes the are to move into a set of V-slotted iron grids, where the are is extinguished rapidly. This paper present the effective method 10 design V-slotted iron plates of the are breaking chamber of molded case circuit breakers. This magnetic force was calculated by using the flux densities in the arc which are obtained by three dimensional finite element method, as a result of that this paper verified by testing that a grid model which has biggest magnetic force is excellent in the are quenching ability.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권12호
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• pp.789-796
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• 2000

This paper deals with magnetic field and characteristic analysis for ring type slotless synchronous motors by using analytical method. Since magnetic air-gap in the slotless motors is much larger than mechanical air-gap, it is necessary to analyze the magnetic flux distribution at the whole magnetic airgap region. therefore, this paper analyzes the duplicated magnetic field derived by both Permanent Magnet(PM) and armature current and estimates the back electromotive force and torque characteristic by subdividing the conductor region. The analysis results are verified by comparing with Finite Element Analysis(FEA) results.

• Journal of Astronomy and Space Sciences
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• 제35권2호
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• pp.55-66
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• 2018

The solar magnetic field plays a central role in the field of solar research, both theoretically and practically. Sunspots are an important observational constraint since they are considered a discernable tracer of emerged magnetic flux tubes, providing the longest running records of solar magnetic activity. In this presentation, we first review the statistical properties of the latitudinal distribution of sunspots and discuss their implications. The phase difference between paired wings of the butterfly diagram has been revealed. Sunspots seem to emerge with the exponential distribution on top of slowly varying trends by periods of ~11 years, which is considered multiplicative rather than additive. We also present a concept for the center-of-latitude (COL) and its use. With this, one may sort out a traditional butterfly diagram and find new features. It is found that the centroid of the COL does not migrate monotonically toward the equator, appearing to form an 'active latitude'. Furthermore, distributions of the COL as a function of latitude depend on solar activity and the solar North-South asymmetry. We believe that these findings serve as crucial diagnostic tools for any potential model of the solar dynamo. Finally, we find that as the Sun modulates the amount of observed galactic cosmic ray influx, the solar North-South asymmetry seems to contribute to the relationship between the solar variability and terrestrial climate change.