• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.638-640
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• 2001

In this paper, system equation of the magnetic equivalent circuit of the induction motor be consist of the magnetomotive force transformation matrix and the flux transformation matrix. The system equation is fed by three phase sinusoidal current and get to magnetomotive force on the teeth. This study confirmed the time and spatial distribution of the magnetomotive force on the teeth created by the winding.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.907-909
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• 2001

This paper proposes the analysis method for the pole change motor that is a capacitor-run single-phase induction motor. As the Magneto motive force(MMF) at 2-role becomes severe distortion, it is necessary to consider the harmonics for the characteristic analysis of the motor. Therefore, the performance of motor is analyzed by equivalent circuit considering the harmonic components. The validity of the proposed analysis method for the pole change motor is verified through simulations and experimental results.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.910-912
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• 2001

The winding design of a capacitor-run single-phase induction motor for changing two poles(2-/4-pole) is proposed for reducing the harmonics of Magneto Motive Force(MMF) in the airgap at 2-role. To improve motor performance, it is important to analyze exactly the harmonics and design the winding pattern for its harmonics reduction. The winding design method to reduce the harmonics is suggested in this paper and its characteristics are analyzed by using equivalent circuit considering harmonic components. The various performances of the pole change motor with the proposed winding pattern are compared with the experimental results.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.189-192
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• 1999

The switched reluctance drive system is known to provide a good adjustable speed and torque characteristics. However, acoustic noise and higher torque ripple are drawbacks. These drawbacks show the fact that SRM drive is not operated with mmf current specified for dwell angle and input voltage. Reducing torque ripple and having precise speed control, PLL technique is adopted. The PLL system in conjunction with dynamic dwell angle control scheme has good speed regulation characteristics. A TMS320F240 based on the DSP is used to realizing this drive system. Test results show that the system has the ability to achieve good dynamic and precise speed control.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.9
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• pp.565-571
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• 2000

SRM has been applied to many commercial applications that require economical advantages and high performance abilities. But it has some drawbacks such as acoustic noise due to the abrupt change of mmf level when commutation. The abrupt change of a phase excitation produces mechanical stresses and it results in torque ripple and noise. This paper deals with an analysis of vibration and noise in SRM drive. Several types of excitation method are taken into account. The 1-phase and 2-phase excitation technique of short-pitch winding 2-phase excitation technique of full-pitch winding are tested. The acoustic noise is reduced remarkably through the sequential phase excitation in the 2-phase excitation. It is because that the scheme reduces abrupt change of excitation level by distributed balanced excitation with free-wheeling during commutation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.4
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• pp.77-77
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• 2001

MMMF(Modified 2D Multi-shell Median Filter)를 기초로 하여 가변 문턱 조건과 홀/짝수 다중셀을 이용한 Adaptive Odd/Even MMF(Multi-shell Median Filter)를 제안하였다. 제안된 알고리즘은 MATLAB을 이용하여 연구하고 테스트하였다. 제안된 알고리즘의 성능은 이미 잘 알려진 이미지에 임펄스 노이즈(Impulse Noise)와 Line Missing을 적용하여 평가하였고 이를 FPGA로 구현하였다. 제안된 가변 문턱 조건은 연산 시간과 불필요한 재배치를 줄였고, 홀수 셀과 짝수 셀은 각각 십자 방향과 대각선 방향의 Line Missing을 복구하였다. 특히 짧은 연산 시간으로 실시간을 요구하는 이미지 처리 분야에서 효과적으로 이용할 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.1
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• pp.193-204
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• 1997

In this research we propose the design of the Order Statistic-Adaptive Weighted Average Hybrid(OS-AWAH) filter which can suppress noise from the corrupted image sequence effectively while preserving the image structure. The proposed filter combines the desirable properties of the order static based spatial filter which can preserve the image structure while reducing noise and the adaptive weighted average based temporal filter which can adapt the filtering weights according to the amount of motion without motion estimation. Performance characteristics of the OS-AWAH filter in noisy sequences containing moving step edges are investigated throuth computer simulations and compared with the median based filters such as 3-D WM(weighted median) filter, MMF (multistage median filter), ADCWM(adaptive directional center weighted median) filter. The visual evaluations are also carried out by applyin gthe filters to the real images. The statistical analysis and experimental reslts show that the OS-AWAH filter is effective in preserving image structures while suppressing noise effectively without motion compensation preprocessing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1321-1327
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• 2006

This paper presents the calculation of unbalanced magnetic pull (UMP) that causes rotor misalignment in induction motor. The excessive noise and vibration will be occurred by means of rotor misalignment. Angular misalignment of rotor will produce air-gap permeance wave which is function of axial and circumferential coordinate. In this paper, the UMP is calculated using permeance and magneto motive force (MMF) in the case of static and dynamic misalignment. Based on the percentage of misalignment, the result shows that the UMP and magnetic pressure are increased according to the increasing of misalignment. The UMP is occurred not only in It frequency component but also the others.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.901-902
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• 2006

In high-speed PM machines, rotor losses form a larger proportion of the total losses than usual in conventional low speed machines. In order to maintain the mechanical integrity of a high-speed PM rotor intended for high-speed operation, the rotor assembly is often retained within a sleeve or can. The sleeve is exposed to field produced by the stator from either the slotting or the mmf harmonics that are not synchronous with the rotor. These non-synchronous fields cause the significant rotor losses. An optimum design of high-speed PM machines requires the accurate prediction for these rotor losses. On the basis of analytical field analysis and 2D finite element analysis (FEA), this paper deals with the rotor losses.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.180-181
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• 2013

This paper represents an analysis of a leakage inductance for a toroidal type flyback transformer. The equation to calculate the leakage inductance is derived using its MMF diagram. The analysis for the different types of the cores and winding structures is also provided using the Maxwell 3D simulation. The winding structures minimizing the leakage inductance are finally discussed, from the simulation results.