• Journal of The Korean Society of Integrative Medicine
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• v.7 no.2
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• pp.11-17
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• 2019

Purpose : The purpose of this study was to determine the effects of specific frequency and application timing of microcurrent (MC) on the mechanical property of muscle caused by delayed onset muscle soreness (DOMS). Methods : The subjects were 32 healthy adults with 8 subjects randomly assigned to four groups (I; 40 Hz MC while inducing DOMS, II; 40 Hz MC immediately after inducing DOMS, III; 284 Hz MC while inducing DOMS, IV; 284 Hz MC immediately after inducing DOMS). DOMS is applied to the biceps brachii muscle while MC was applied at an intensity of $300{\mu}A$ for 10 minutes. The mechanical properties of muscle were measured before and immediately after DOMS. Results : In terms of muscle tone, there were significant differences in interaction effects between time and groups. Regarding muscle elasticity and stiffness, there were no significant differences in interaction effects between time and groups but there were only significant differences in main effects based on time. Conclusion : The results indicated that 40 Hz MC had an effect on reducing muscle tone regardless of application timing. However, both 40 Hz and 284 Hz MC did not trigger changes in muscle elasticity and stiffness regardless of application timing.

• Journal of Oral Medicine and Pain
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• v.33 no.1
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• pp.97-103
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• 2008

The purpose of this study was to examine the effect of LLLT on current perception threshold in trigeminal neuralgia patients. Affected site and non-affected site was irradiated by GaAlAs diode laser. Current perception threshold was evaluated with $Neurometer^{(R)}$ CPT/C before and after LLLT. As an outcomes,CPT were obtained. We made a comparision of these values and the results were as follows. 1. There were no significant difference in CPT between affected site and non-affected site before and after LLLT irradiation. 2. There were no significant difference in CPT between affected site and non-affected site after LLLT irradiation. 3. But, CPT values of $A{\beta}$ fiber incresed slightly on both site after LLLT irradiation

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.3
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• pp.66-74
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• 2005

This paper presents an implementation of digital servo speed control system of SPMSM(Surface-mounted Permanent Magnet Synchronous Motor) for industrial application with Direct Torque Control(DTC) using TMS320F2812 DSP. Although, the vector control scheme is adapted in many industrial servo system, but the DSP calculation ratio is increased by reference frame transformation and SVPWM of vector control. Therefore, this paper investigate the possibility of DTC scheme for industrial servo drive system instead of vector control scheme. DSP calculation ratio is compared between vector control and DTC algorithm in addition to the characteristic of speed control response. The suggested SPMSM control system shows the possibility of DTC scheme for industrial servo motor drive system instead of a vector control algorithm.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2005-2010
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• 2011

On AC railway systems, the neutral sections are installed in front of substations and sectioning posts in order to avoid crash between power that have differing phases. In case railway vehicles pass through these neutral sections, it is necessary for them to switch to coasting driving by notch-off. This may reduce speed of the vehicles, resulting lowered train operation efficiency. The usage of automatic power switching systems makes it possible to pass neutral sections at notch-on, enhancing operation efficiency so that it is appropriate for high-speed railway applications. This paper analyzed inrush current of main transformer that installed on the train while passing through the neutral section using the simulator.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.95-97
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• 2007

Transformer inrush current can cause the voltage drop by source impedance. The accurate modeling and analysis for inrush current is first step to limit the inrush current and improve the power qualify. This paper presents the modeling of transformer inrush current by EMTP-RV using Jeju power system, Korea. The method to model the hysteresis curve of transformer in EMTP-RV is discussed. Simulations demonstrate the verification of modeling of inrush current by comparing the data recorded in field with simulation values and analyzing the harmonics of inrush current.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.37-39
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• 2008

This paper suggests a decision scheme for optimal insertion resistance in an Superconducting Fault Current Limiter (SFCL) application to reduce the transformer inrush current. This scheme and the SFCL model are implemented using Electromagnetic Transient Program (EMTP). We determine the optimal SFCL resistance by EMTP simulation, and this value is applied to model the SFCL by EMTP. The simulation results show the validity and effectiveness of the suggested scheme and the ability of a SFCL to reduce the inrush current.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.151-156
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• 2002

The output voltage of Synchronous Generator is regulated constantly by field current control in excitation system. A synchronous generator is equipped with an automatic voltage regulator(AVR), which is responsible for keeping the constant output voltage under normal operating conditions about various levels. High frequency PWM converter (Current Mode Control Buck converter) type excitation system for synchronous generator is able to sustain output voltage level properly when the fault condition happened. This paper deals with the design and evaluation of the excitation system controller for a synchronous generator to improve the steady state and transient stability. The simulation and experimental results show that the proposed excitation system is improve the respons time by the AVR(automatic voltage regulator) of 50kW synchronous generator that is applied the current mode control excitation system.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.147-150
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• 1999

SRM drives generate large vibration and acoustic noise because it is commutated individually by step pulse m.m.f on each phase pole. The frequency or motor speed of peak vibrations and acoustic noises is coincided with the natural resonant frequency of the magnetic structure and frame material. And this radial vibration force is induced on the phase commutation region. This paper suggest the new electromagnetic structure of SRM with auxiliary commutation winding excited d.c e.m.f.. This phase- commutating winding is coupled magnetically between one phase winding and the vibrating force is falled down. As a result, SRM with d.c exciting commutation winding is very useful to reduce vibration and acoustic noise of SRM drive.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.416-418
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• 1997

Stable power source and fast control response are important for the generator excitation system. To stabilize the control of excitation circuit the PI controller for excitation current has been used. But the response of the system with this conventional control technique is very poor, especially in transient response with a predictive current control, the response of the excitation system can be improved. In this study, it is verified by the PSIM simulation.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.85-86
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• 2008

This paper analyzes the improvement of the power quality by the reduction of the inrush current. We analyze the existing methods and simulate the segragated point-on-wave closing method selected as the proper method. And we attempts to use the resistive type Superconducting Fault Current Limiter(SFCL) to reduce the transformer inrush current. We simulate the various insertion resistances and analyze the voltage drop. All simulation are performed by EMTP. The simulation results show the validity and effectiveness of a SFCL application and the segragated point-on-wave closing method to reduce the inrush current and improve the power quality.