• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1990.10a
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• pp.35-40
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• 1990

Temperature distribution of high pressure mercury lamp has been mesured as a function of time using spectroscopic method. Sampling signal which is synchronized by lamp voltage was used to mesure temporal line intensity at each radius. To obtain radial temprature distribution, the mesured intensity was transformed into radial line intensity by Abel's formula. Absolute temperature profile was calculater from relative intensities of spectral lines as a function of line and tube radius. The temperature profile is very similar to the electrical tube current profile.

• Tribology and Lubricants
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• v.19 no.4
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• pp.187-194
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• 2003

This paper describes the characteristics of wheel wear of high speed train running on the conventional line. Conventional line has many curved tracks that cause severe wheel flange wear. The influences of lubrication, cant deficiency, curve radius on wheel wear are also described considering the operation performance of the highspeed trainset. A method of calculation using contact patch work model is presented for determination of the evolution by wear of railway wheels.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.878-883
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• 2005

Sleeper, the ballast, and ballast mat in the high-speed railroad line are modelled using a two-dimensional discrete element method to generate circle and line elements. Stress transfer mechanism from the sleeper to the subgrade via the ballast is analyzed. The behavior of ballast bed of the high-speed railroad line is also accessed with the model.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.82-87
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• 2010

A measurement system of contact force between overhead contact line and pantograph of train is developed which measures the contact force by using four sets of full-bridge strain gauges instead of load cells and accelerometers. The sensors are installed on the pan head of pantograph and the measured data from the sensors are transmitted to a server system in the train by way of wireless Lan. This configuration of the measuring system makes it easy to install on the trains without any alteration of train system. The measurement system is applied to KTX on the Kyungbu high speed line, and the measured contact force data shows good agreement with those measured by load cell and accelerometers. The waveform of the contact force between overhead contact line and pantograph contains essential information about their conditions. The proposed measurement system can probe any defects on overhead contact lines with train running at high speed, which will be a powerful solution for the maintenance of long-distance overhead contact lines.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.623-628
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• 2007

This paper presents the new power line coupler which is applicable to spread spectrum power line communications. The proposed coupler maintains the adequate value of a capacitor between the transmitter mode and the receiver mode using a switch. In the transmit mode, the relatively high value of the capacitor is chosen to minimize the attenuation of transmitted signals. In the receiver mode, the value of the capacitor is chosen to be small enough so that the coupler attenuates power line noises. This coupler reduced the magnitude distortion due to having a high Q value and the power consumption caused by the AC current flowing into the capacitor. The simulation and measurement results show the improved performance in the transmitter and receiver mode, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.103-105
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• 2008

In, this paper, we consider the relation between on-line monitoring and diagnostics on the one hand and high-voltage (HV) withstand and partial discharge (PO) on-site testing on the other. HV testing supplies the basic data (fingerprints) for diagnostics. In case of warnings by on-line diagnostic systems, off-line withstand and PO testing delivers the best possible information about defects and enables the classification of the risk. Because alternating voltage (AC) is the most important test voltage, the AC generation on site is considered. Frequency tuned resonant (ACRF) test systems are best adapted to on-site conditions. They can be simply combined with PO measuring equipment. The available ACRF test systems and their application to electric power equipment -from cable systems to power transformers - is described.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.190-196
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• 2009

In this paper, performance of a turbo-coded OFDM system is analyzed and simulated in a power line communication channel. Since the power line communication system typically operates in a hostile environment, turbo code has been employed to enhance reliability of transmitted data. The performance is evaluated in terms of bit error probability. As turbo decoding algorithms, MAP (maximum a posteriori), Max-Log-MAP, and SOVA (soft decision Viterbi output) algorithms are chosen and their performances are compared. From simulation results, it is demonstrated that Max-Log-MAP algorithm is promising in terms of performance and complexity. It is shown that performance is substantially improved by increasing the number of iterations and interleaver length of a turbo encoder. The results in this paper can be applied to OFDM-based high-speed power line communication systems.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.59-65
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• 1997

The calibration of O.M.D is carried out experimentally and is analysed theoretically. O.M.D experimentally measures the change in optical density of artificially contaminated oil which contains Fe powder of 5, 10, 20, 30, 40, 50, 70, 100, 200 ppm. The change in optical density, D$_1$ means the logarithmic transmittance of I$_0$ over $I_1 D_2$ denotes the logarithmic transmittance I$_2$ over I$_1$ on electromagnetic force which arranges the ferrous particles along the line of magnetic force. The theoretical D$_1$ which increases linearly as increasing Fe concentrations, is analysed by light attenuation theory. The difference between theoretical D$_1$ and experimental D$_1$ is due to the attenuation of micro bubbles and the agglomeration of fine particles in the sample oil. The calibrated O.M.D is applied to the sample oil from the high-powered diesel engine. Also the results are compared with those out of the off-line techniques such as JOAP and ICP.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.8
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• pp.16-25
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• 1994

The prediction of crosstalk in one of important problems in estimating the EMC of a system for high speed digital signal transmission. Crosstalk curves are shown in terms of characteristic impedance of lines spacing between lines and rise time of pulse by using general multiple coupled transmission line equation and harmonic-balance method. The coupled symmetrical two-line on dielectric material epoxy-glass FR 4(${\varepsilon}_r$), is fabricated to measure crosstalk occuring at the near end and far end of the passive line. The inter-line is inserted to reduce crosstalk between two microstrip lines. The simulation results and the measurement results are shown and found to be very close.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1390-1396
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• 2007

The line-start permanent magnet synchronous motor has a high efficiency and an advantage in constant speed operation regardless of the effect of load variation. However, it is difficult to predict the performance of characteristics accurately, because of the unbalanced starting torque with the initial starting position of the rotor and the generation of a break torque. In this paper the dynamic characteristics of the line-start permanent magnet synchronous motor are described and compared with those of the squirrel-cage induction motor through the simulation to find the characteristics of the permanent magnets and the rotor bars in the line-start permanent magnet synchronous motor. Finally this paper gives the comparison between the simulation results and the experimental results.