• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.2
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• pp.69-75
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• 2005

In order to improve the reliability of high voltage rotating machines and mold transformers, it is necessary to understand the breakdown mechanism and life assessment of the high voltage winding parts. Especially the on-line PD test provides the ability to monitor effects, such as slot discharge, internal discharge, and end-winding discharge without interrupting the electrical machines, this method has been proven the major testing technology. Capacitive couplers have been the most widely used sensors for the on-line partial discharge detection in rotating machines nowadays. This paper deals with the electrical characteristics and long-term reliability of a ceramic coupler(CC), which can be easily mounted into high voltage input terminal part, has been developed and tested to continuously measure PD activity during operating condition. This paper presents electrical characteristics (dielectric loss angle, capacitance, PD inception level, breakdown voltage, and frequency response bandwidth) and long-term life test result of the developed 6.6 kV class on-line ceramic coupling sensor. It was found that this sensor had good electrical characteristics to detect PD activity during the operating condition with its detection frequency band is between several and several tens MHz. Also, the voltage life of the 6.6kV class ceramic coupler was calculated over 60 years.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.65-67
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• 2001

PLC (Power Line Communication) is the communication method using the existing power line installed in houses and offices to convert and transmit high frequency communication signal from tens of KHz to tens of MHz, and receive the filtered signal using high frequency filter. The advantage of PLC is that PLC uses the existing power line installed in houses and offices so it does not require separate power line. Easy and convenient access using electric outlets is another advantage of PLC. However, PLC has some disadvantages such as limited transmission power, high load interference and noise, variable signal attenuation, characteristic of impedance selective possibility of frequency property. This study designed the boiler temperature control system by unit using the modem designed on the basis of technology used for PLC modem, and designed remote control system using internet. After conducting experiments with those two systems, it was possible to control stably. By commercializing this product, we can avoid unnecessary heating of separate temperature control unit, and save the cost according1y, and it is possible to control on a remote site using internet in a more convenient way.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.442-449
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• 2000

Before the complete construction of new high-speed line between Seoul and Pusan, KTX is going to operate on both new high-speed line between Seoul and Daegu and electrified conventional lines between Daegu and Pusan. Then, the wheels of KTX are going to operate on various rails such as KS50N and KS60 of conventional line as well as UIC60 of high-speed line. Also, conventional line will have a mixed traffic mode with various types of trains operating on it, such as Saemaul and Mugunghwa. Hence, this study reviews the wear phenomena of wheels and rails in geometrical point of view by comparing their profiles. The analyses of the results show that because UIC60 rail is designed for KTX, KS50N rail whose profile is similar to that of UIC60 will not have any impact on the shape of wheel wear. On the other hand, KS60 rail is expected to have partial wear on both the flange of KTX wheel and the gauge corner of the rail in the initial stages. However, the operation of the trains whose wheels have 1/20 conicity will cause partial sidewear on the inside of the rail and the movement of the contact point between KTX wheel and the rail toward the inside of the track. As a result, the flange wear of KTX wheel will be reduced and the formation of wear-equilibrium profile will be faster.

• Korean Journal of Animal Reproduction
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• v.22 no.2
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• pp.127-136
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• 1998

A chimeric gene comprising murine whey acidic protein(mWAP) and human growth hormone(hGH) was used to produce transgenic rats express hGH and secrete it into the blood. Two lines of transgenic rats carrying the mWAP/hGH construct were established; High line was characterized by relatively high levels of serum hGH, and low line had relatively low levels. The secretory profiles of rat GH(rGH) as well as hGH, the transgene product, were obtained in transgenic males and females of low line; both hGH and rGH serum levels were flattened with no episodic fluctuations, and the overall mean concentration of rGH was significantly lower than in normal littermates. Although the animals of High line showed an acceles, as assessed by vaginal opening and occurrence of first ovulation, advanced by 7∼8 days in both lines of animals. Accordingly, the body weight at puberty of low line transgenic females was much lower than that of normal littermates, indicating that continuous hGH expression could induce precocious puberty without enhancing the growth rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.6
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• pp.1562-1574
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• 1998

We, in this paper, have implemented T1, E1 and fractional E1 HDSL(High-bit-rate digital subscriber line) function over an ATM switching system. The maxi$\mu$ loop lengths for subscriber service and cell loss rates to meet the bit error rate of 10$^{-7}$ at transmission of 2B1Q HDSL data E1 rate over existing telephone copper wires in the presence of the significant impairments such as NEXT(Nearned crosstalk), impulse noise, power line noise and longitudinal over the CSAs environment consisting of 26 gauge and 25 gauge unloaded copper telephone lines has assessed. HDSL will intially be used to serve private-DS1, ISDN-BRA, and DLC feeders, later DS1 extension from optic fiber cable. We also present market provision for the HDSL.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2263-2268
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• 2008

We investigated the malfunction and destruction characteristics of microcontroller devices under high power electromagnetic(HPEM) wave by magnetron. HPEM was rated at a microwave output of 0 to 1,000 W, at a frequency of 2,450${\pm}$50 MHz and was radiated from the open-ended standard rectangular waveguide(WR-340) to free space. The influence of different reset-, clock-, data-, and power supply-line lengths has been tested. The variation of the line length was done with flat cables. The susceptibility of the tested microcontroller devices was in general much influenced by clock-, reset-, and power supply-line length, little influenced by data-line length. Further the line length was increased, the malfunction threshold was decreased as expected, because more energy couples to the devices. The surfaces of the destroyed microcontroller devices were removed and the chip conditions were investigated with microscope. The microscopic analysis of the damaged devices showed component and bondwire destructions such as breakthroughs and melting due to thermal effects. The obtained results are expected to provide fundamental data for interpreting the combined mechanism of microcontroller devices in an intentional microwave environment.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.567-573
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• 2003

Korean High Speed Train (KHST) has been tested on high speed line in JungBu site since it was developed in 2002. The data acquisition system was developed to accomplish successfully this on-line test for proving the dynamic Performance of KHST. This system was consist of the personal computers based on National Instrument PXI modules and the test programs based on Labview 6i. This paper shows that this system is efficient to acquire the test data through the multi-channels connected the accelerometers which located in long distance places and flexible to change and add channels for data acquisition. The dynamic analysis of an on-line test is very complicate because the environmental conditions, as examples radius of curve, inclination of the track, tunnels, bridges, and so forth, and running conditions, as examples driving, braking, the number of working motors, and so forth, have an effect on the results. Therefor, the analysis method is important and this paper proposes the efficient procedure graphically, showing the proposed method simplify the accelerations of 5th bogie frame acquired during the on-line test for KHST.

• Communications of Mathematical Education
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• v.24 no.3
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• pp.627-658
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• 2010

The introduce and accurate understanding of the concept of tangent line is very important in Mathematics education and its applications. In this study, we investigated the introduction method in the textbook for tangent line and its concepts. And we studied the effective teaching methods for the accurate understanding using Lakatos learning theory, GSP and related precedence studies. Finally we suggest the teaching plan for the equation of for the tangent line in the high school and apply to the High school students.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.6
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• pp.409-416
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• 2005

For broadband high-data-rate power line communication with the allocated frequency bandwidth from 2 to 30 MHz on medium voltage (MV) distribution power lines, a signal coupling unit is developed. The coupling unit is composed of a coupling capacitor for coupling communication signal, a drain coil, and an impedance matching part. The coupling capacitor made of ceramic capacitor is designed for transmission property of better than 1 dB in the frequency range. The drain coil is used for preventing low frequency high voltage from junction of medium voltage power line in case that a coupling capacitor is not working properly any more. Also, using ferrite core, a novel broadband impedance matching transformer is developed. A complete coupling unit with a coupling capacitor, a drain coil, and a matching transformer is housed by polymer for good isolation and distinguishing from high voltage electric facilities. Each is fabricated and its frequency behavior is tested. Finally, complete signal couplers are equipped in a MV PLC test bed and their performance are measured. The measurement shows that the coupling capacitor works excellently.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.1
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• pp.1-5
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• 2019

The overhead contact line (OCL) is a key piece of equipment for transmitting electrical energy to the pantograph of rail cars. Recently, a 400 km/h OCL was applied to the Honam high-speed line, and its performance was examined by running HEMU-430X. For the study, we analyzed the current of catenary wire concurrently while running HEMU-430X in the Honam high-speed line. Specifically, this study recorded the currents for each speed during operation of the railway vehicle. The analysis of the frequency of line current showed generation of third-harmonics, 15th-harmonics, 17th-harmonics, and 19th-harmonics. The current of catenary wire is a basic technology assessment used to determine the electrical safety of electric railway systems, and it can be used as a technology for analyzing circulating currents generated in the current configuration, as well as for analyzing electric fatigue of the OCL components.