• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1595-1600
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• 2012

This paper shows an improvement of the WRSM (Wound Rotor Synchronous Motor) by satisfying the voltage limit condition at high speed. After that, it compares the performance of the improved WRSM to that of the IPMSM (Interior Permanent Magnet Synchronous Motor). The comparison has been made under the condition where the dimension of the motor is identical to that of the IPMSM, having the rotor switched to a wounded rotor form. Moreover, this paper compares the Basic Model of the two motor, and estimates the parameters of the WRSM, thereby proposing the method to improve high speed performance. Furthermore, this paper presents the feasibility of switching the conventional motor into rare-earth-free motors for traction purpose.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1643-1648
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• 2009

The braking system of train must posses the large baking effort in order to stop the train safety within the limited traveling distance. but, the excessive braking effort has been deteriorated the ride comfort due to high level of deceleration and jerk, and sometimes occurred the skid. because the applied braking force exceeds the allowable adhesive force. this skid causes not only to increase the a stopping distance but also to deteriorate the safety of train and damage the rall surface by wheel flat. In the present paper, braking force for disk brake of Tilting Train eXpress(TTX) was measured though on convention line test and the traction force was estimated by using the analytic model in skid condition. also, we have discussed the relationship between the bake force and traction force in starting condition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.883-887
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• 2016

The power supply system in Korean electrified railway has adopted AT feeding. If a fault occurs in some substation for any reason, the vicinity substation must feed electric power on the outage substation through catenary. So, the feeding distance grows twice of the normal state at extended feeding condition. If substation's feeding distance is longer than normal condition, the catenary impedance and train to supply electric power from the substation. Therefore, the severe voltage drop can occur and power supply shall be not allowed. This paper presents the model of compensator against voltage drop using multi-port network algorithm. Whole traction power supply system can be analyzed with this model. Computer simulation including this model is performed based on real train schedule and increased schedule in case studies.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1371-1373
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• 2000

In this paper, the complex accelerating degradation of traction motor driven with VVVF controlled inverter were performed on the form coil samples with the 200 Class insulation system. in order to evaluate the reliability and the long-term life. After aging, the dielectric and PD properties were investigated on the 10 cycles aging sample in the range of $20{\sim}160[^{\circ}C]$ and AC $250{\sim}2250[V]$ to diagnosis the condition of end-life and find the dominative factors of degradation.

• Journal of Industrial Technology
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• v.30 no.A
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• pp.31-35
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• 2010

In this paper, a speed estimation method at coasting operation in an induction motor speed sensorless control for railway vehicle traction systems is presented. At coasting operation, there is no information obtaining rotor speed since all switches of an inverter are turned off. The inverter frequency should be synchronized with the rotor frequency for repowering at coasting condition. The proposed method injects DC current to the induction motor during a short time, then the flux angle and rotor speed needed for control can be estimated rapidly.

• Archives of Plastic Surgery
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• v.35 no.3
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• pp.349-353
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• 2008

Purpose: There are 3 well-known surgical procedures to treat Pierre Robin sequence: tongue-lip adhesion, distraction osteogenesis of mandible, and tracheostomy. The classical tongue-lip adhesion is an effective way to keep airway. The tongue, however, becomes quite non-mobile and appears dormant until the patient could control upper airway and the adhesion can be maintained for prolonged period. Most of all, this procedure does not provide the correction of the micrognathia. Distraction osteogenesis is a good technique to correct micrognathia and to prevent tracheostomies in patients with Pierre Robin sequence. But airway keeping procedure is needed during the distraction period. The purpose of this study is to determine the usefulness of temporary tongue-lip traction during the initial period of mandibular distraction in Pierre Robin sequence patients with severe airway problems requiring operative procedure. Methods: It was a prospective study of 2 Pierre Robin sequence patients aged between 4 months and 6 months requiring surgical procedure to correct recurrent and severe pulmonary complications. Two patients underwent distraction osteogenesis of mandible. During the operation, deep one tension suture was performed to tract the tongue and lip. When the patient gained control of upper airway at the initial period of distraction and micrognathia was corrected, the traction suture was removed. Results: All patients were followed up. No patients complained severe pulmonary complications and tracheostomy could be avoided. No patients had severe pulmonary complication. The pulmonary condition of patients was good. Conclusion: In severe Pierre Robin sequence case, temporary tongue-lip traction is a good assistant method in distraction osteogenesis because this method can avoid tracheostomy.

• Journal of the Korean Society for Railway
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• v.12 no.2
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• pp.249-253
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• 2009

This paper dealt with the insulation evaluation by a measurement of partial discharge(PD) on traction motors used in a hybrid vehicle. The PD method has been accepted as an effective and a non-destructive. technique to evaluate insulation performance of low-voltage electric and electronic devices. In this paper, the PD measurement system which was manufactured with a coupling network, a low noise amplifier, and an associated electronics is described. The PD measurement system has the frequency bandwidth of $1[MHz]{\sim}30[MHz]$ at -3 [dB] and the stable sensitivity of 19 [mV/pC] for the traction motor. From the experimental results, discharge inception voltage (DIV) and apparent charge (q) were $1,100[V_{rms}]$ and 105 [pC] for the used motor, and $1,400[V_{rms}]$ and 84 [pC] for the new one. By comparing the DIV and q, we could evaluate the insulation condition for the traction motors.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1320-1326
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• 2011

The maximum speed of high-speed rail is restricted to various factors such as track condition including slope and radius, tunnel and dynamic stability of vehicle. Among the various factors, traction effort and resistance to motion is principal and basic factor. In addition, at high speed over 300km/h, aerodynamic drag amounts up to 80% of resistance to motion, that it can be said that aerodynamic drag is the most important factor to decide the maximum speed of high-speed rail system. This paper deals with a measure to increase the maximum speed of high-speed train by reducing aerodynamic drag. The traction effort curve and resistance to motion curve of existing high-speed train under development has been employed to set up the target of aerodynamic drag reduction to reach up to 500km/h without modification traction system. In addition, the contribution of various sources of aerodynamic drag to total value has been analyzed and the strategy for implementation of aerodynamic drag reduction has been discussed based on the aerodynamic simulation results around the train using computational fluid dynamics.

• Journal of the Korean Society for Railway
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• v.9 no.4 s.35
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• pp.357-361
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• 2006

This paper dealt with the performance evaluation and the diagnostic techniques of lightning arresters for DC electric traction vehicle. Field Measurements on the protective operation of lightning arresters against surge currents were carried out on running vehicles to acquire the data necessary for the diagnosis. The frequency and the magnitude of surge events were analyzed. Surge currents of $1\sim3$ times were recorded in one running service route and their magnitudes were ranges of $150A\sim2kA$. Also, an acceleration experiment on a lightning arrester by the standard lightning impulse current of 8/20 us and 5 kA was performed to know the aging characteristics. After the surge current application of 3,000 times, the reference voltage decreased by 4.5 %, and the leakage current was below 10 uA at the continuous operating voltage and about 50 uA at the rated voltage. From the experimental results, we propose a decision level of leakage current for the arrester used in this paper and designed an arrester tester which analyzes arrester condition by the magnitude of leakage current.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.491-499
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• 1999

This paper is on the high perfonnance propulsion IGBT VVVF inverter adopted new technique for railways. To prove the high performance and stabilit~r of traction, running tests are carried out under the simulated condition alike real field. The tests are perfonned on not only a steady states but also a transient states such a as input voltage variation using inertia load equivalent to 160tons train. The vector control technique is a adopted to improve traction for 4 motors. The low switching synchronous PW1\l method based on a space v voltage vector modulation is pro\XlSed as the optimal method for propulsion system railway. The output voltage l is controlled continuously to six step by prolxlsed ovennodu]ation technique without sudden torque variation.