• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.3
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• pp.145-151
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• 2000

The topological investigations regarding magnetic circuit geometry and winding form of the transverse flux machine have brought up a variety of constructable arrangements with different features for several types of application[1, 2]. Here with, a novel PM-exited linear motor with inner mover, based on the transverse flux configuration leads to a considerable increase in power density for moving part. In this study we designed PM-exited transverse flux linear motor for ropeless elevator, whose output power density is higher and weight is lighter than conventional linear synchronous motors. When the designed motor in this study is applied to ropeless elevator, it is possible to increase power density more than 400% comparing with PM exited linear synchronous motor. The result of this study can be utilized for ropeless elevator or gearless direct linear moving system with high output[3].

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.6-8
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• 2004

Recently, the PM type stepping motor preferred solution for many small electronics position determination devices since it is small in size. Thus, there are glowing demands for permanent magnet(PM) type stepping motor that greater mechanical output, smaller size. This paper deals with a study of the miniaturization of the PM type stepping motor with claw-poles. We introduced the small-sized PM type stopping motor that has new structure and analyzed the magnetic characteristic of it versus general type model using 3-D finite element analysis(FEA).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.3
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• pp.34-39
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• 2008

The purpose of this paper is characteristic analysis of multi-disk axial-gap pm motor for turbo compressor. The axial-gap permanent magnet motor has shown a growing interest in high-speed application for its high-efficiency, compact size and low vibration characteristics due to core-less structure. To achieve high-power, the axial-gap PM motor has multi-disk structure of stator and rotor disk. Because of its complicated magnetic flux path, it is not easy to calculate a dynamic characteristics using finite element analysis. In this paper, the simplified 2-D unfolded model to predict EMF characteristic is presented. To verify thesuggested 2-D unfolded model analysis of back-EMF characteristic was calculated and compared 3-D finite element. Finally the proposed method is verified by experimental results and shows good agreement with test results.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.3
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• pp.269-275
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• 1988

In this paper, a high efficiency motor drive system which improves the multi-step response of PM step motors by reducing the transition time of the motor drive current, is studied by designing a dual-voltage drive circuit. The designed drive circuit eventually prevents the motor from decreasing drive torque while the stepping rate is increased. The method of designing a dual-voltage drive circuit with the motor specifications is suggested in order to improve the response of step rate and drive efficiency. Also, despite improving the power efficiency on motor driving, the response characterstics suggested by the motor manufacture's specifications are satisfied without any special deficiency.

• Annals of Clinical Neurophysiology
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• v.5 no.1
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• pp.21-26
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• 2003

Background & Objectives: Hyperexcitablity of motor system is a well-established characteristic pathophysiologic finding of amyotrophic lateral sclerosis (ALS). Whereas little is known about the source of excitability according to the progression of the disease. We evaluated the excitability and its source in advanced ALS patients using transcranial magnetic stimulation (TMS). Meterial & Methods: Motor evoked potentials (MEP) by TMS were recorded for abductor pollicis brevis muscles in 20 patients, 11 men and 9 women, with ALS. Mean age was $54.2{\pm}12.1years$, and mean disease duration was $13.9{\pm}13.4years$. Serial magnetic stimulations were applied to get the parameters; excitability threshold (ET), amplitude and latency of MEP. We also had a facilitated MEP (fMEP). Results: The parameters were analyzed according to the clinical settings. ET was higher in ALS(mean $63.5{\pm}18.1$) than normal control (mean $46.0{\pm}8.4$, p<0.01). Amplitudes of MEP were reduced in ALS ($2.6{\pm}3.6mV$; control $6.5{\pm}3.1mV$, p<0.01). Duration of the disease and ET showed significant inverse correlation (Spearson correlation coefficient = -0.57, p<0.01). Duration of the disease and fMEP/MEP ratio showed less but also significant inverse correlation (Spearson correlation coefficient, r = -0.52, p < 0.05). Conclusions: Lower ET in advanced ALS patients, in spite of decreased fMEP/MEP ratio, may indicate the hyperexcitability of lower motor neurons in these patients. This study suggests that lower motor neurons is hyperexcitable due to upper motor neuron dysfunction at advanced stage.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.101-103
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• 2003

This paper deals with field distributions in high speed motor with two different types of diametrically magnetized PM rotor, one is that rotor is consisted of PM and shaft, the other is that rotor has only PM. In case of high speed motor with rotor consisted of PM and shaft, this paper predicts field distributions in high speed motor according to the quality of shaft. The magnetic field solutions are derived analytically in terms of vector potential and 2-D polar coordinate system. The results are shown in good conformity with those obtained from the commonly used finite element method.

• Journal of Pharmacopuncture
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• v.3 no.1
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• pp.89-99
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• 2000

This report was done to observe the effect of Hominis placenta herbal acupuncture on Bell's palsy. The study group comprised 16 patients who arrived at Woo-suk university oriental hospital from January, 1999 till January, 2000 for Bell's palsy. All patients were divided into two group. One was herbal acupunture group, and the other was control group. Acupunture group was done herbal acupuncture therapy on the facial acupuncture points. Followings are achievement and a term of each group. In herbal acupuncture group, 100% motor recovery was 7 case, 75% was 1 case, and 25% motor recovery term was $7.38{\pm}5.21$ days, 50% was $11.00{\pm}6.16$ days, 75% was $15.13{\pm}9.55$ days, 100% was $23.14{\pm}7.97$ days. In control group, 100% motor recovery was 4 case, 75% was 2 case, 25% below was 2 case and 25% motor recovery term was $11.17{\pm}4.96$days, 50% was $18.17{\pm}6.82$ days, 75% was $29.50{\pm}6.95$ days, 100% was $44.00{\pm}11.49$ days. The above results indicate that Hominis placenta herbal acupuncture is a useful effect on Bell's palsy. thus, continuous herbal acupunture study will be needed for more clinical application on Bell' palsy.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.6
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• pp.536-543
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• 2004

Slotless Permanent Magnet Brushless DC Motor(PM BLDC) with the characteristics of high speed and power density has been more widely used In Industrial and factory machine. Generally, PM BLDC meter is necessary that the three Hall-lCs evenly be distributed around the stator circumference in case of the 3 phase motor. The Hall-ICs are set up in PM BLDC Motor to detect the main flux from the rotor. therefore the output signal from Hall-ICs is used to drive a power transistor to control the stator winding current. However, instead of using three Hall-ICs, if it used only one Hall-IC, we can estimate information of the others phase in sequence through a rotor This paper identified the characteristics and performance by using one Hall-IC with the 3-phase, 2-pole, 6-slot PM BLDC motor.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.6
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• pp.888-894
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• 1986

In this paper, a phase locked loop control system is designed to have high performance and stability in a 2-phase bifilar winding PM step motor. The BODE diagram analysis method is used to improve the stability and dynamic characteristic of the closed loop control system. Also, a PLL servo is used to accomplish high-precision speed and to attain smooth ness. In applying the PLL control to the step motor, a new design method is suggested to solve the control problem which occurs as a result of the limited maximum acceleration of the step motor. A simple design method is suggested without using the complicated multi-step characteirstic of the step motor in constant voltage driving. Computer simulation results agree clorelg with experiments, indicating that the PLL servo system of the step motor designed is very useful.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.450-457
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• 1998

Abstract - Linear Synchronous Motor has a large airgap comparing with rotary-type motor and especially, Permanent Magnet Linear Synchronous Motor(PM-LSM) which uses permanent magnet as a magnetic field, has a very large effective magnet airgap owing to permanent magnet structure. Accordingly, in case of 2-D analysis of the motor, the analysis error becomes large because leakage flux by which normal direction of the analysis region can not be considered, In this paper, the characteristic of PM-LSM for Maglev vehicle is analyzed exactly by 3-D Finite Element Method(3-D FEM). As the result, the effect of lateral-direction airgap magnetic flux density distribution on the analysis precision has been investigated and the motor characteristics according to primary motor parameter have been also made clear quantitatively. The accuracy of 3-D FEM has been confirmed by comparing the calculated results with the experimental results.