• 대한전기학회논문지
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• 제39권11호
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• pp.1153-1162
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• 1990

The torque ripple reduction method is studied to improve the speed fluctuation of permanent magnet flat type brushless DC motors. To reduce the torque ripple, this study developed the compensation method of the 5'th harmonics component of air gap flux waveform which pass through the driving coils. 1/2 inch VTR was considered. As the result of this study, we can reduce the torque ripple and the speed fluctuation of the capstan motor about 20% then before and we can obtain not only better characteristics of wow/flutter but more useful capstan motors which can be applied in the multi-function VTRs.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권4호
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• pp.145-151
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• 1999

This paper presents the characteristic analysis method of PMLSM based on the Space Harmonic Analysis method considering the effect of stator slots. The magnetic field for unslotted primary can be easily calculated by the conventional space harmonic analysis method and the resultant magnetic field including slot effect is obtained using the concept of the virtual Equivalent Magnetizing Current(EMC) on primary core. And the influence of space harmonics in airgap flux density and static thrust due to slots is evaluated. In this paper, the results of the analytical method are compared with not only the experimental ones but ones of FEM to verify the validity of the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.1947-1950
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• 1998

GTO inverter used for traction motor drives includes harmonics in the output current and torque by the limitation of switching frequency. However, the hybrid PWM method, using SPWM in low frequency range and SHE PWM in upper frequency range, can be obtained the relative less harmonic characteristic. The transient reaction, which the magnetic flux and the torque is altered and instantly the large current is flowed, may be produced at the mode change. This paper presents the techniques which can reduce the transient reactions produced in the gear changing of inverter fed traction motor drives operating in the hybrid PWM. The results are verified by the simulations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.52-54
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• 2004

현대정보화산업에서 배전계통의 부하는 첨단 제어장치, 다양한 반도체 전력변환 설비, OA기기 및 PC 둥의 사용으로 배전계통의 중성선에 영상 고조파가 많이 발생한다. 이것을 최소화하기 위해서 본 연구에서는 중성선의 영상전류를 제거하는 장치인 특수 리액터를 설계하고 유한요소프로그램(Flux2D)을 이용하여 특성을 해석하여 검증하였다. 최적설계를 위하여 누설자속의 최소화, 코아 및 동손의 최소화를 위한 설계알고리즘도 구성하여 최적설계안을 제안하였다.

• Journal of Magnetics
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• 제22권2호
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• pp.306-314
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• 2017

Nowadays power quality effects on induction motors have gained significant attention due to wide application of these motors in industry. The impact of grid voltage fluctuations on the induction motor behavior is one of the important issues to be studied by power engineers. The degree of iron saturation is a paramount factor affecting induction motors performance. This paper investigates the effects of voltage fluctuations on motor magnetic saturation based on the harmonic content of airgap flux density by finite element method (FEM). It is clarified that the saturation harmonics under normal range of voltage fluctuations have not changed significantly with respect to pure sinusoidal conditions. Experimental results on a 1.1 kW, 380 V, 50 Hz, 2 pole induction motor are employed to validate the accuracy of the simulation results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.782-784
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• 2004

The purpose of this paper is the selection of an optimum slot combination minimized the harmonics of air gap flux density and e.m.f., and reduction of the magnetic noise through the theoretical study on the cause and result of the magnetic noise. The analysis method is performed by the magnetic noise equivalent program and the FEM.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1050-1052
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• 2005

In this paper, air gap flux density is calculated by permeance model which can consider the effects of the stator slot and the salient pole shape of the salient synchronous generator. No load Electro-motive force(EMF) of the short-pitched and distributed stator winding is also calculated. Therefore, it's very convenient to calculate the THD of the no load EMF for the user's request, in the first design state.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.217-219
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• 2004

The second harmonic component could be decreased by magnetizing inrush when there have been changes to the material of the iron core or its design methodology. The higher the capacitance of the high voltage status and underground distribution, the more the differential current includes the second harmonic during the occurrence of an internal fault. Therefore, the conventional second harmonic-restrained RDR needs modification. This paper describes an advanced numerical algorithm that utilizes terminal voltage, differential current harmonics, harmonic ratio, and flux-differential current slope. Based on the results of testing with WatATP99 simulation data, the proposed algorithm was proven to be faster and more reliable.

• 대한기계학회논문집
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• 제14권6호
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• pp.1652-1660
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• 1990

본 연구에서는 원관내에서 복사에 관여하는 고온의 가스유동에 의한 복사열전 달과 대류열전달간의 상호작용에 대해 실험과 수치해석을 통하여 고찰하고자 한다. 실험으로는 프로판가스의 화염생성에 의한 속도, 온도 및 벽면에서의 열유속분포를 측 정하고, 수치적으로는 냉염(cold flame) 상태서 측정한 난류요동성분과 연소시의 입구 속도와 온도를 초기조건으로 하여 밀도와 점성계수의 온동에 따른 변화를 고려한 K-.epsilon. 모델과 구조화근사법 및 최근에 개발되어 사용되기 시작한 Weighted Sum of Gray Gas- es모델을 사용하여 속도, 온도 및 열유속 분포를 계산하여 수치해석의 결과와 실험결 과를 비교함으로써 모델의 타당성을 검증하고, 복사에 의한 열전달량과 대류에 의한 열전달량을 분리하여 각 모드가 온도분포 및 열유속분포에 미치는 영향을 고찰하고자 한다.

• Journal of Magnetics
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• 제20권3호
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• pp.273-283
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• 2015

In this study, we propose an analytical model for studying magnetic fields in radial-flux permanent-magnet eddy-current couplings by considering the effects of slots and iron-core protrusions on the eddy currents. We focus on the analytical prediction of the air-gap field by considering the influence of eddy currents induced in conducting bars. In the proposed model, the permanent magnet region is treated as the source of a time-varying magnetic field and the moving-conductor eddy current problem is solved based on the resolution of time-harmonic Helmholtz equations. The spatial harmonics in the air gap and in slots, as well as the time harmonics are all considered in the analytical calculation. Based on the proposed field model, the electromagnetic torque is computed by using the Maxwell stress tensor method. Nonlinear finite element analysis is performed to validate the analytical model. The proposed model can be used for permanent-magnet eddy-current couplings with any slot-pole combination.