• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1057-1059
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• 2003

This paper presents drive analysis of slotless air-cored PM linear synchronous motor using two-dimensional analytical method. In order to calculate dynamic characteristic, back-EMF and linkage flux are calculated by Permanent Magnet Field and also inductance are given by slotless winding current coil. PMLSM drive simulation is performed by PI control system.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.930-932
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• 2003

As Synchronous Reluctance Motor gives reluctance torque, An inductance is an important parameter that is proportional to torque. To achieve the high performance in sensorless control, it is necessary to consider exact inductance values because the inductance is not a constant parameter anymore. Therefore, this paper shows the inductance measurement using DC current decay test, AC standstill test, and AC standstill test considering Cross Magnetization. This inductance has also been compared with the result that is analyzed by FEM.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.15-17
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• 2009

초전도선재를 사용한 전력기기에서 발생하는 교류손실은 전력기기의 효율을 저하시키기 때문에 매우 중요한 요소이다. 본 논문에서는 교류손실을 저감시키기 위해 분할형 초전도 연속전위도체(Continuously Transposed Coated Conductor, CTCC)를 제작하였으며, 제작된 분할형 CTCC에 교번자장을 인가하였을 때 발생하는 교류손실을 측정하였다. 측정 결과 분할된 필라멘트 수와 선재의 적층수가 증가함에 따라 교류손실 값의 변화 패턴을 확인하였다. 또한, 분할형 CTCC에 가해지는 외부교번 자장의 인가 각도에 따른 자화손실을 측정하여 그 경향을 확인하였다.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.945-950
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• 2013

This paper deals with the ellipse permanent magnet machines for the minimization of torque ripple based on electromagnetic field theory. On the basis of a magnetic vector potential and a two dimensional (2-D) polar system, analytical solutions for flux density due to permanent magnet (PM) and current are obtained. In particular, the analytical solutions for mathematical expressions of magnets with different circumferential thicknesses can be solved introducing improved magnetization modeling techniques. The analytical results are validated extensively be nonlinear finite element solutions, a reduction of torque ripple can be achieved.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.28-30
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• 1998

In this paper, voltage source FEA considering hysteresis characteristics for a simple electrical system is presented because most electrical machines is used under the voltage sources. The magnetization dependent hysteresis model is used for this analysis and the magnetic materials considered in this simulation are iron core and semi-hard material. For a sinusoidal voltage sourece, we got acceptible current wave form which is calculated.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.833-836
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• 1995

A capacitor discharge impulse magnetizer is used to produce a high current pulse of short duration in a magnetizing fixture for magnets of the various shapes. The problem of designing custom fixtures for magnetization has often been considered more of conventional experience than a scientific theory. Therefore, the design of magnetizingfixture has until recently been a "cut and try" process. It was common to literally blow up one or more fixtures beforeachieving the desired results. Finite element CAD package allow the design of such a fixture. Since magnetizing fixtures come in a variety of sizes and shapes, there is usually no simple analysis method that can be used to estimate the field characteristics of the fixtures. Instead, one typically uses finite element analysis. FEA program MAXWELL is the primary tool used here. The purpose of this study was a examine both theoretically and experimentally the field characteristics inside the fixture. Independent of sizes and shapes of magnetizing fixtures, the desired magnetic field can be obtained with resonable predictability. The experimental results have been achieved using a 1000[V], 22.4[KJ] capacitor discharge magnetizer and iron-core fixtures.

• Journal of Magnetics
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• v.21 no.4
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• pp.491-495
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• 2016

We developed an embedded Object-Oriented Micromagnetic Frame (OOMMF) script schemes for more flexible simulations for complex and dynamic mircomagnetic behaviors. The OOMMF can be called from any kind of softwares by system calls, and we can interact with OOMMF by updating the input files for next step from the output files of the previous step of OOMMF. In our scheme, we set initial inputs for OOMMF simulation first, and run OOMMF for ${\Delta}t$ by system calls from any kind of control programs. After executing the OOMMF during ${\Delta}t$, we can obtain magnetization configuration file, and we adjust input parameters, and call OOMMF again for another ${\Delta}t$ running. We showed one example by using scripting embedded OOMMF scheme, tunneling magneto-resistance dependent switching time. We showed the simulation of tunneling magneto-resistance dependent switching process with non-uniform current density using the proposed framework as an example.

• Progress in Superconductivity
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• v.3 no.1
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• pp.70-73
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• 2001

We report the spin injection and transport properties of three terminal devices of Co/Au/$YBa_2$$Cu_3$$O_{y}$(F/N/S) tunnel junctions by injection of spin-polarized quaiparticles using a cobalt ferromagnetic injector. The observed current gain depends on the thickness of Au interlayer and is directly related to the nonequilibrium magnetization due to spin relaxation effects. The tunnel characteristic of a F/N/S tunnel junctions exhibited a zero bias conductance peak (ZBCP). The suppression of the ZBCP was observed due to the suppression of Andreev reflection at the interface, which is due to the spin scattering processes at the interface between a ferromagnetic and a d-wave superconductor.r.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.4
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• pp.356-363
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• 2003

An eddy current testing system was developed for detection of flaws in the ferromagnetic steel tubes. Because the eddy current signals from the ferromagnetic steel tubes could be distorted easily due to an irregularity of magnetic permeability, magnetic saturation is required to suppress this variation of magnetic fields. A magnetic saturation probe with the Hemholtz coil was designed for the inspection of the steel tubes. The bandwidth pass filters were adapted to minimize the noise from the DC magnetization. When using the designed test probe, the flaw signals could be discriminated from the noise. The system was tested at the production line and showed a capability of detecting flaws, like a drilled hole of the diameter of 2.0mm at the moving speed of 1m/sec.

• Journal of the Korean Magnetics Society
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• v.14 no.1
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• pp.33-37
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• 2004

Cu$_{0.1}$Fe$_{0.9}$Cr$_2$S$_4$ has been studied with Mossbauer spectroscopy, x-ray diffraction, vibrating sample magnetometer (VSM), and magnetoresistance (MR) measurement. The crystal structure was determined to be a cubic spinel with lattice parameter a$_{0}$=9.9880 $\AA$. The MR measurements show a semiconductor behavior below 110 K and metal behaved above 100 K. The temperature dependence of magnetization of Cu$_{0.1}$Fe$_{0.9}$Cr$_2$S$_4$ was reported. In addition to a large irreversibility between the zero-field-cooling (ZFC) and the field-cooling (FC) magnetization at applied field H=100 Oe, a cusp-like anomaly was observed in both the FC and ZFC curves. It shifted toward the lower temperature region with increasing magnetic field, and then showed convex type maximum at 110 K, under the applied field of 5 kOe. The Mossbauer spectra were measured from 15 K to room temperature. The asymmetric line broadening was observed for the sample Cu$_{0.1}$Fe$_{0.9}$Cr$_2$S$_4$, and it was considered to be dynamic Jahn-Teller relaxation. The charge state of Fe ions was ferrous in character. The unusual reduction of magnetic hyperfine field below 110 K was interpreted in terms of cancellation effect between the mutually opposite orbital current field (H$_{L}$) and Fermi contact field (H$_{C}$).