• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.641-643
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• 2005

It is usual to operate the long transmission line with transposition of each phase in order to avoid voltage unbalance due to unbalanced capacitances at each phase of the line end. This paper described the Ferranti voltage rise of line end, charging current and secondary arc current according to the transposition of line or not. The positive and negative sequence current was derived by the phase current, and then the unbalanced rate was calculated. Then, we obtained the reclosing dead time of the single phase reclosing scheme for 500 kV single circuit horizontal arrangement transmission line system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.739-742
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• 1997

Continuously variable transmission(CVT) mechanisms are proposed, which can offer a backward mode, a geared neutral, an underdrive mode and an overdriver mode. They are not required of a starting device as a torque converter. CVT mechanisms developed here present two distinct operating modes which are a power circulation mode and a power split mode. The transition of two modes takes place at the particular CVU speed ratio. For these CVT mechanisms, performance analysis related to speed ratio, power ratio and theoretical efficiency are executed.

• 산업기술연구
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• 제29권B호
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• pp.145-149
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• 2009

A RF-DC converter is one of the most important components for a wireless power transmission. It has been developed for many applications such as space solar power system, and Radio Frequency Identification(RFID). In this paper, we designed three types of RF-DC converter and compare the performance of each. All types RF-DC convertoer have a maximum conversion efficiency at input power level of 0 dBm~5 dBm and RF-DC converter of third type was the best performance that has a 21.9% of conversion efficiency.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.903-908
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• 1998

This paper aims at investigating the characteristics of the operating modes of two-module Thyristor Controlled Series Compensator (TCSC) in a power transmission system. The operating modes of two-module TCSC are defined, analyzed and compared to those of single-module TCSC are defined, analyzed and compared to those of single-module TCSC. The load flow program, the stability calculation program and Electro Magnetic Transient Program (EMTP) simulation of a TCSC power transmission system are developed for the performance evaluation of two-module TCSC as a power flow controller. In the process of the simulation study, the potential problem areas of the TCSC power transmission system are identified.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.449-451
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• 2001

This paper described the switching overvoltage analysis on the 345kV and 154kV transmission system by EMTP(Electromagnetic transient Program) for the enactment of current insulation design standards of KEPCO. The air clearance design of current transmission tower was reviewed and revised by the calculated result, considering swing angle for the each type of insulator string by the wind velocity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2368-2370
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• 1999

A nationwide survey for electric and magnetic fields(EMFs) near overhead transmission lines has been conducted. The median values of the electric and magnetic fields of 208 transmission lines were 0.50 kV/m and 12.6 mG, respectively. The maximum values were 3.16 kV/m and 125 mG. The measured EMFs were compared with the calculated ones. The causes of the discrepancy between measured and calculated EMFs are also discussed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
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• pp.195-199
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• 2003

BEE 802.11 Wireless LAN protocol uses fixed transmission power. It does not consider a power control mechanism based on the distance between the transmitter and the receiver in order to improve overall channel utilization. In home environment, where stations generally lie around an AP, the AP is subject to use transmission power more than it needs. And wireless LAN stations may require different minimal desired received power. If there are many adjacent BSSs in densely populated WLAN area, they might cause RF interference to one another. In this paper we focus on the improvement of aggregate utilization by mitigating RF interference among BSSs. We show that RF interference by APs can be reduced by controlling transmission power using Link Margin information. The reduced interference will then lead to the increased aggregate throughput which is efficient resource utilization.

• 대한전기학회논문지:전력기술부문A
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• 제52권8호
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• pp.437-443
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• 2003

In this paper an expert system is developed to decide the resetting area of protective devices in power transmission systems. A configuration change in power transmission networks from a substation extension such as new line or bus addition need resetting of protective devices around the point of configuration changes. To find the resetting area in complex power system is very difficult, especially when the distance protective relays are considered to be reset. The proposed expert system, in this paper to find the resetting area has many rules based on the changes of fault currents and apparent factors from the power system alteration. It solves the problem to find relay resetting area using the network information in the database and the rule-base. The case study shows a result of the problem to find relay resetting area in KEPCO system when there is any configuration change.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.334-336
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• 2003

This paper describes the influences of the large scaled wind farm interconnected with 154 kV power networks on the operational characteristics of distance relay applied in the transmission line. The wind farm composed of wind turbine generators are one of the great energy sources: they can supply the power into an interconnected network not only the normal conditions, but also the fault conditions of power network. Therefore, the distance relay applied in the transmission tine may mal-operate due to the contribution of wind farm. This paper presents the operational characteristics of distance relay for the fault occurred in the transmission line interconnected with wind farm. Simulation results show that it is difficult to recognize the fault location due to the power output of wind farm.

• 전기전자학회논문지
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• 제22권4호
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• pp.1050-1055
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• 2018

In this paper, we analyzed the sensitivity of matching elements for the dual-band operation of a power amplifier with composite right/left-handed (CRLH) transmission lines. Metamaterial theory enables CRLH transmission to support arbitrary impedance matching at dual frequencies. In general, at sub-GHz range, the CRLH matching networks are commonly implemented with lumped elements, which are prone to manufacturing distribution. In order to reduce the effect from the distribution of element values in design, we suggest a method to analyze the sensitivity of matching elements from the performance aspect of power amplifiers. Based on the analysis, a 40dBm dual-band power amplifier operating at 0.7GHz and 1.5GHz is designed.