• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.384-386
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• 1998

In the emergency case such as a single line operation in a double line section because of a line broken or train's mal-operation, single line equipments that can operate without a line indication are needed. The main purpose of this study is to verify and analyze the availability of the single line operation that is able to operate without the indication of up or down line, and to offer a realizably alternative method to improve this situation. In order to carry out this study, we concentrated on getting related information. And to adopt the single line operation to existing line, the technology survey of other countries signalling system and the technical analysis of the interior signalling equipment were performed. As a result of this study, the required system and effect of the single line operation system were represented.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.2
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• pp.162-169
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• 2016

Gyeong-bu railway line in Korea between Seoul and Cheon-an was built as two double tracks. A four-display signaling system, only for the metro line, was installed on the second double track so KTX and conventional trains can only operate on the first double track. This study suggests a method to allow KTX and conventional trains operated on the five-display signaling system to respond to accidents and track defects on the second double-track under the four-display signal system by means of problem analysis, calculation of breaking distances for KTX and conventional trains at each break mode, and improvement of the ATS system.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.768-769
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• 2008

This paper examines an design of double-barrier rotor structure for improving the efficiency performance in a single-phase line-start permanent magnet(LSPM) motor. By utilizing the advantages of double-barrier rotor design that by increasing reluctance torque generation to compensate magnet torque production, the copper loss reduction is achieved. The optimal approach of response surface methodogy(RSM) is performed for determining a optimum double-barrier rotor structure. The improving of efficiency performance is confirmed by finite element method(FEM) and test.

• Journal of The Korean Astronomical Society
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• v.53 no.2
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• pp.35-42
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• 2020

We analyze high dispersion emission lines of the symbiotic nova AG Pegasi, observed in 1998, 2001, and 2002. The Hα and Hβ lines show three components, two narrow and one underlying broad line components, but most other lines, such as H_I, He_I, and He_II lines, show two blue- and red-shifted components only. A recent study by Lee & Hyung (2018) suggested that the double Gaussian lines emitted from a bipolar conical shell are likely to form Raman scattering lines observed in 1998. In this study, we show that the bipolar cone with an opening angle of 74°, which expands at a velocity of 70 km s^-1 along the polar axis of the white dwarf, can accommodate the observed double line profiles in 1998, 2001, and 2002. We conclude that the emission zone of the bipolar conical shell, which formed along the bipolar axis of the white dwarf due to the collimation by the accretion disk, is responsible for the double Gaussian profiles.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.5
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• pp.231-238
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• 2006

This paper analysed the induced current density inside human body of hot-line worker for 765kV double circuit transmission line according to locations of human body. Human model was composed of several organs and other parts, whose shapes were expressed by spheroids or cylinders. Organs such as the brain, heart, lungs, liver and intestines were taken into account. Applying the 3 dimensional boundary element method, we calculated induced current density in case a worker was located inside and outside a lowest phase of 765 kV transmission line in which a 60% current of maximum load flowed. As results of study, we found a maximum induced current density in all organs was less than $10mA/m^2$ when a wonder was outside. As one in brain and heart was higher than $10mA/m^2$ when a worker was inside, we propose a method for lowering current density.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.591-594
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• 2009

A new gerbera variety "Red Line" was released by the National Institute of Horticultural & Herbal Science (NIHHS) in 2008. A cross was made between "Mirage" with orange and double and "Rose" with red and semi-double in 2005. After investigation of the characteristics for four years (from 2005 to 2008), it was selected specially for the use of cut flower. "Red Line" is a vigorous cultivar with red (RHS R44B), black center and semi-double. The average flower diameter is 12.7 cm, large flower. And inner ray floret and disc diameter are 8.10 cm and 2.80 cm, respectively. It produces a large yield with continuous supply of flowers and has adequate peduncle height. We believe that "Red Line" has a great potential for expanding cultivated area of domestic gerbera cultivars and increasing farmers-income.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.3
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• pp.37-42
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• 2022

A high-performance wideband transition from microstrip to waveguide is proposed. This transition is designed by consideration of gradual field transformation and optimal impedance matching between microstrip line and fin-line. Clear design guidelines of proposed transition using fin-line taper with offset DSPSL (double-sided parallel stripline) are provided to determine the transition shape and the transition length. The fabricated transition exhibits less than 0.67 dB insertion loss per transition for frequencies from 85 to 108 GHz, and less than 1 dB insertion loss from 83 to over 110 GHz. Proposed transition is expected compact radar and various applications.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.169-171
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• 2002

The western route of KEPCO's 765kV transmission line has been tentatively operating as 345kV voltage before commercial operation. After finishing the test operation of 765kV substation in 2002. KEPCO decided to operate the 765kV line for commercial operation. During the applying of 765kV voltage to the transmission line, double circuit transmission line will be operated with two voltage grades of 765kV and 345kV. Because the earthing switch is installed on both end of transmission line, we had estimated the electrostatic induction voltage and electromagnetic induction current before the line energizing in order to confirm the ratings of earthing switch. The induced voltage and current is very important for the maintenance of parallel circuit. This paper describes the simulation study of electrical phenomena such as electrostatic induction voltage from the parallel line and electromagnetic induction current from the parallel circuit. The transmission line model was developed by EMTP (Electro-Magnetic Transient Program).

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.208-211
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• 2003

The western route of KEPCO's 765 kV transmission line has been tentatively operating as 345 kV voltage before commercial operation. KEPCO decided to operate the 765 kV line for commercial operation after completing the test operation of 765 kV substation in 2002. In the process of energizing the line as 765 kV voltage, double circuit transmission line will be operated with two voltage grades of 765 kV and 345 kV. As the earthing switches are installed on both ends of the line, electrostatic induction voltage and electromagnetic induction current were calculated prior to the line energizing in order to confirm the ratings. The induced voltage and current are important for the maintenance of the parallel circuit. This paper presents the simulation results of electrical phenomena such as electrostatic induction voltage and electromagnetic induction current from the parallel line. The transmission line was modeled by EMTP (Electro-Magnetic Transient Program). The simulation results were compared with the measured results at the field.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.151-159
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• 2003

According to the records, approximately 50 percent of power failure were caused by lightning. Conventional fault preventive measures against lightning include reduction of the footing resistance of the tower, multiplication of overhead ground wires and unbalanced insulation of the double circuit transmission tower. In addition to these, transmission line arresters have been recently appeared as an alternatives. In this paper an unbalanced insulation method with transmission line arrester was assumed as another countermeasure against simultaneous double circuit trip of 154 kV transmission line by lightning strike. The lightning performance of line arrester was compared with conventional insulation concept using different numbers of porcelain and glass insulator. Larger numbers of insulator simply increase flashover current level by lightning but the lightning performance doesn't proportional to it. EMTP simulation and predictive calculation of lightning failure rate were carried out to evaluate the performance.