• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.501-504
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• 1999

Chua's circuit is a simple electronic network which exhibits a variety of bifurcation and attractors. The circuit consists of two capacitors, an inductor, a linear resistor, and a nonlinear resistor. In this paper, a transmitter and a receiver using two identical Chua's circuits are proposed and a synchronizations of lossless transmission line are investigated. Since the synchronization of the transmission system is impossible by coupled synchronization, the drive-response synchronization theory were used. As a result, the chaos synchronization has delay characteristics in the lossless transmission system caused by the line parameters L and C.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.11
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• pp.960-965
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• 2015

In this paper, a coupled line directional coupler using an LUC(Low-pass filter Unit Cell) of artificial transmission line is presented. The conventional coupled line coupler is limited in length by the ${\lambda}/4$ transmission line while the proposed coupling structure is implemented smaller than $90^{\circ}$ by inserting the phase delay line between two coupled line, reduced in physical size by configuring a phase delay line with an LUC having the characteristics of a typical transmission line in a particular frequency. A coupler having -10 dB coupling factor at the center frequency of 700 MHz is designed, fabricated. The measured result agrees well with that of conventional one. The length of the fabricated coupled line coupler has about 45 % in length compared to the conventional one.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.224-227
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• 1997

This study discuss two subjects : maximization of transmission capability and regulation of voltages along line within the permissible bounds. Series and parallel line compensation methods have been applied for those purposes using capacitors and reactors. In this paper, the effect of series and shunt line compensation for symmetrical line is analyzed. The results obtained in this paper can be applied 765kV class EHV transmission system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.10
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• pp.502-509
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• 2002

In the analysis of lightning surges, transmission towers are usually simulated by ATPDraw. The modeling of transmission towers is an essential part of the traveling wave analysis of lightning surges in transmission lines. The tower model is applied to the 154kV transmission tower of which surge performance characteristics are measured Tower surge response is computed using nonuniform, single-phase line models for both transmission tower and ground wire. The overvoltage will effect to the underground transmission line. The underground cable is combined by duct and trefoil type, and the each arrester is placed on the leading-in tube and outgoing tube. This paper analyzed the effect of lightning overvoltage on the underground cable system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.4
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• pp.151-155
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• 2006

HVAC transmission lines must be designed to satisfy environmental regulations. Therefore it is necessary to pre-evaluate environmental problems for transmission line designer using prediction program. In this study, environmental design software, TLCALC(Transmission Line CALCulation) for transmission lines was developed as a comprehensive window program. It has 6 modules that are audible noise, radio noise, television noise, magnetic field, electric field and conductor surface gradient. TLCALC solved a few problems in use of the existing foreign tools and took several advantages as follows; (1) It is a common tool that solves calculating limitations of foreign formulas, (2) It has wide application ranges and enhances accuracy of prediction. (3) It can be applied to almost transmission line configurations in Korea. (4) Experienced designers can get the results of calculation within about 15 minutes. Because the use of TLCALC is easy and practical, this program will be usefully applied to the environmental friendly design and construction of transmission lines. In the future, it is expected that public complaints and social environmental cost will be reduced by the use of TLCALC.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2462-2467
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• 2009

This paper proposes a dual band branch line coupler (BLC) using a composite right/left handed (CRLH) transmission line. The existing dual band BLCs with open stubs require hundreds of line impedance for the open stub as the frequency bands approach to each other, so it has been almost impossible to realize them. However in the proposed BLC, a CRLH transmission line replaces the open stub with an extremely high line impedance so that the BLC circuit may be realized even two frequencies are close to each other. As an example, a dual band BLC operating at 1800MHz and 2300MHz (the frequency ratio is 1:1.28) is designed and measured. Open stubs with $560\Omega$ line impedance are replaced by CRLH transmission lines for realizing the dual band BLC. The measured performances prove that the dual band operation is well acceptable and the proposed design method is successful even the ratio between two frequencies is not around two nor more.

• 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.

• Journal of Electrical Engineering and Technology
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• v.8 no.2
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• pp.364-370
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• 2013

In the current paper, we propose a new modeling algorithm to analyze the coupling between an incident electromagnetic field (EMF) and a twisted conducting line, which is a kind of non-uniform line. Typically, analysis of external field coupling to a uniform transmission line (TL) is implemented by the Baum-Liu-Tesche (BLT) equation so that the induced load responses can be obtained. However, it is difficult to apply this method to the analysis of a twisted conducting line. To overcome this limitation, we used a chain matrix composed of ABCD parameters. The proposed algorithm expands the dimension of the previous chain matrix to consider the EMF coupling effectiveness of each twisted pair, which is then applied to multi-conductor transmission line (MTL) theory. In addition, we included a comparative study that involves the results of each method applied in the conventional BLT equation and new proposed algorithm in the uniform two-wire TL case to verify the proposed method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2305-2310
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• 2011

This paper describes a design of dual band balanced amplifier using a lefted handed meta-material transmission line structure for high frequency application. Meta-material transmission lines have been known to have dual band frequency responses. A dual band branch line hybrid coupler is designed using the meta-material transmission lines, and measured at first. Two identical dual band amplifiers are also designed, built and tested using the same meta-material transmission structure. The proposed dual band balanced amplifier is composed of those dual band branch line hybrid coupler and amplifiers. In order to suggest an design example, a prototype of dual band balanced amplifier is built and measured at the dual frequencies, 1800MHz($f_1$) and 2300MHz($f_2$). The simulation and measurement show that the fabricated balanced amplifier operates well at the desired dual frequencies bands with the gain of 11.12dB and 17.67dB at $f_1$ and $f_2$, respectively, with a good agreement with the simulation results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.133-138
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• 2001

The high-speed data service is on the increase and on the development because of using the coaxial cable which hold the most part of subscriber's loop, the transmission rate in a subscriber line has influenced by an external-electromagnetic factor such as the falling of a thunderbolt and the electromagnetic induction on transmission line. this external environment gets the noise of a communications line and then has an influence to the transmission speed and quality for the high-speed data service. this paper makes an analysis of noise characteristic appeared a subscriber communications line, measures a transmission speed per each cable-distance and resolves these relationship by putting the noise, which has affected extensively the transmission quality of ADSL service, into a subscriber line.