• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.9
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• pp.427-433
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• 2005

In DC tracking power supply system, ground faults are currently detected by the potential relay, 64P. Though 64P relay detects ground fault, it cannot Identify the faulted region which causes long traffic delays and safety problem to passengers. Two new ground fault protective relay schemes that can identify the faulted region are presented in this paper. One is bus differential protective relay and the other is ground overcurrent protective relay. Both type of relays is similar in principle to the ordinary bus differential protective relay and the ground overcurrent relay used in other power system. In DC traction power supply system, since it is ungrounded, ground fault current is not big enough to operate those relays. To solve the problem, a current control device, called device 'X', is newly introduced in both system, which enables large amount of ground fault current flow upon the positive line to ground fault. Algorithms for these relays are developed and their validity are verified by EMTP simulation.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.212-214
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• 2007

Regenerative energy which is generated during brake periods of DC traction might cause malfunction or destruction of rectifier or any other power conversion devices caused the increment of DC line voltage. Regenerative energy storage system using super-capacitor is one of the method to control the DC line voltage safely. And super-capacitor is very important device as energy storage device. Therefore, In this paper, we designed the regenerative energy storage system using super-capacitor and propose the method about predicting the lifetime of super-capacitor established in storage system. According to the this research, we can estimate the proper replacement moment for the existed super-capacitor due to the safety of the system. And improve the reliability of regenerative energy storage system using super-capacitor.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.109-116
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• 2010

The magnet wheel which generates on its interfacing conductive part a repulsive force and a traction torque by rotation of permanent magnets is used to manipulate the conductive plate without mechanical contact. Here, the air-gap magnetic field of the magnet wheel is shielded partially to convert the traction torque into a linear thrust force. Although a magnitude of the thrust force is constant under the fixed open region, we can change the direction of force by varying a position of the shield sheet. So, the spatial position of conductive plate is controlled by not the force magnitude from each magnet wheel but the open position of shield sheet. This paper discusses non-contact conveyance system of the conductive plate using electromagnetic forces from multiple magnet wheels.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.4
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• pp.640-645
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• 2015

Near surface transit system has should be constructed as installation cost of light rail transit with elevated track. So, distance between two substations is longer than conventional system. The long feeding distance results in severe voltage drop. This paper proposes a PWM rectifier instead of diode rectifier. The PWM rectifier has some advantages. This is able to control output voltage constantly to reduce voltage drop and to use regeneration power without additional inverter. This paper analyse on improved voltage profile and cost of substation with PWM rectifier. The analysis of voltage profile use PSIM, and the installation cost of substation with PWM rectifier is compared to substation with diode rectifier.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.385-388
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• 2001

In this paper, the gearless traction machine drive system using a permanent-maget motor for high-speed elevators is addressed. This application of permanent-magnet motor to the elevator traction machine enables several improvements including higher efficiency, better ride comfort, smaller size and weight, and so on. PWM boost converter is also adopted so that DC-link voltage regulation, hi-directional power flow, and controllable power factor with reduced input current harmonics are possible. To increase reliability and performance, the control board, which can include the car and group controller as well as PWM converter and inverter controller, is designed based on TMS320VC33 DSP The simulator system for high-speed elevators has been developed so that the drive system of high-speed elevator can be tested without my limitation on ride distance and the load condition. Some experimental results are given to verify the effectiveness of the developed system.

• Journal of Power Electronics
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• v.10 no.6
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• pp.647-659
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• 2010

This paper presents a part of North Africa/Europe collaboration results in education to develop project-oriented courses in power electronics and motor drive field. The course aims to teach Permanent Magnet motor drives close to a real world project of significant size and depth so as to be motivational, namely mobile robot project. Particular skills, student will acquire, are those relative to the detailed design and implementation of PM motor controllers in DSP based rapid prototyping environment. Simulation work is completed using graphical modeling tools in Simulink/Plecs, while real-time implementation is achieved by means of eZdspF2812 board and Simulink/TI C2000 Embedded Target tools. This flexible development environment fit the robot traction system very well and provides exactly the functionality necessary for an efficient PM motor drives teaching as demonstrated by a set of simulation and experiments.

• Clinical Endoscopy
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• v.51 no.6
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• pp.552-557
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• 2018

Although colonoscopy was originally a diagnostic imaging procedure, it has now expanded to include an increasing range of therapeutic interventions. These procedures require precise maneuvers of instruments, execution of force, efficient transmission of force from the operator to the point of application, and sufficient dexterity in the mobilization of endoscopic surgical instruments. The conventional endoscope is not designed to support technically demanding endoscopic procedures. In case of colonoscopy, the tortuous anatomy of the colon makes inserting, moving, and orientating the endoscope difficult. Exerting excessive pressure can cause looping of the endoscope, pain to the patient, and even perforation of the colon. To mitigate the technical constraints, numerous technically enhanced systems have been developed to enable better control of instruments and precise delivery of force in the execution of surgical tasks such as apposing, grasping, traction, counter-traction, and cutting of tissues. Among the recent developments are highly dexterous robotic master and slave systems, computer-assisted or robotically enhanced conventional endoscopes, and autonomously driven locomotion devices that can effortlessly traverse the colon. Developments in endoscopic instrumentations have overcome technical barriers and opened new horizons for further advancements in therapeutic interventions. This review describes examples of some of these systems in the context of their applications to advanced therapeutic colonoscopy.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1407-1413
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• 2011

This paper studied on the VVVF Inverter for 1C4M propulsion system of railway traction. The paper includes the comparison along a VVVF Inverter electric power conversion element for an electric railcar(GTO, IGBT). These inverters are composed of high power IGBTs and controlled by compact control units. The stack is simplified and optimized by using plate bus and IGBT driver units of hybrid-type.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.190-193
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• 2004

Energy recovery in the regenerative region is very important when SRM is used in traction drive. This paper suggests multi-level inverter which is useful for motoring and regenerative operation. The proposed method is verified through simulations and experiments.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.97-100
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• 1999

AC to DC single phase PWM converter for traction application requires rated high power and voltage. Therefor, series or parallel operation converters are necessary with considering the limitation of the power device specification. This paper compares the characteristic between two parallel operation of conventional PWM converter and Single phase three level converter about comparison of power circuit, cooling system control method and harmonic current by computer simulation.