• 대한전기학회논문지:전력기술부문A
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• 제55권12호
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• pp.555-560
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• 2006

As it has been reported that more than 60% of transmission line faults occurs due to lightning strokes, lighting is one of concerned issues in electric power utility company. Most of transmission line is double circuit in Korea. Double circuit outages account for 33.7 percent of total lightning faults from 1996 to 2004. Even though transmission fault might be cleared shortly by protective system, it could deteriorate the power quality accompanied with sag or flicker. Moreover, double circuit fault may lead to more aggravated situation, for instance, blackout. To Protect transmission lines from lightning stroke, reduction of tower footing resistance, multiple ground wires and unbalanced insulation in double circuit lines have been adopted. In this paper, we would like to introduce insulation design standards for lightning protection of Korea Electric Power Corporation.

• Carbon letters
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• 제26권
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• pp.61-65
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• 2018

Comprehensive calculations of the Rh decoration effect on zigzag CNTs with n ranging from 7 to 12 were conducted in this work to understand the effect of Rh doping on geometric structures and electronic behaviors upon metallic and semiconducting CNTs. The obtained results indicated that Rh dopant not only contributes to the deformation of C-C bonds on the sidewall of CNTs, but also transforms the electron distribution of related complexes, thereby leading to a remarkable increase of the conductivity of pure CNTs given the emerged novel state within the energy gap for metallic CNTs and the narrowed energy gap for semiconducting CNTs. Our calculations will be meaningful for exploiting novel CNT-based materials with better sensitivity to electrons and higher electrical conductivity compared with pure CNTs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.9-11
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• 2005

kEPCO is now conducting a project called the "Feasibility Study & Basic Designs for the 500kV Transmission System in Myanmar" as its second overseas project following the "Development Study on the rover System Network Analysis in Myanmar" performed from 2001 to 2002. As a part of this project, this paper deals with the analysis process and results of the demand forecasts, master plan for transmission system expansion, and the major factors for the new 500kV transmission facilities.

• ETRI Journal
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• 제31권6호
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• pp.806-808
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• 2009

A new computationally efficient algorithm-based propagator method for two-dimensional (2-D) direction-of-arrival (DOA) estimation is proposed, which uses two parallel uniform linear arrays. The algorithm takes advantage of the special structure of the array which enables 2-D DOA estimation without pair matching. Simulation results show that the proposed algorithm achieves very accurate estimation at a computational cost 4 dB lower than that of standard methods.

• 산업경영시스템학회지
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• 제25권1호
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• pp.14-19
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• 2002

This paper describes an automatic parts design system for gears, brake, and clutch. These parts are important components of the power transmission assembly. In conventional design process, the design of power transmission requires a number of recurrent calculations and drawings. In this paper, we propose a three-dimensional automatic design system that reduces the number of recurrent calculations and drawings. The system consists of three modules for designing gear, brake, and clutch. The proposed system has been applied to develop a transmission of forklift truck and shown to be a useful system.

• 조명전기설비학회논문지
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• 제26권1호
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• pp.75-81
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• 2012

In this paper, the wireless power transfer system using the magnetic resonance was designed, analyzed by circuit analysis methode and the calculated transfer function was compared with the measured one. The self-resonant coil was made up of the commonly used capacitor which had the lumped capacitance and it enabled the stable magnetic resonance not to be affected by the circumstance. The transmission efficiency of this system was 70[%] at the 15[cm] between the transmission and receiving coil and the measured transfer function was similar to the calculated one, which means the circuit analysis methode is valid in this system. When the intermediate coils were added between the transmission and receiving coil, the transmission efficiency was increased, which produced the increase of transfer distance. In the case of the five intermediate coils adding, the 35[%] transmission efficiency was achived at the 90[cm] distance.

• KIEE International Transactions on Power Engineering
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• 제12A권1호
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• pp.31-35
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• 2002

This paper presents a new operation scheme of UPFC to minimize both generation costs and active power losses in a normal operation state of power system. In a normal operation, cost minimization is a matter of primary concern among operating objectives. This paper considers two kinds of costs, generation costs and transmission losses. The total generation cost of active powers can be minimized by optimal power flow, and active power losses in the transmission system can be also minimized by power flow control of UPFC incorporated with minimization of generation costs. In order to determine amounts of active power reference of each UPFC required for the cost minimization, an iterative optimization algorithm based on the power flow calculation using the decoupled UPFC model is proposed. For verification of the proposed method, intensive studies have been performed on a 3-unit 6-bus system equipped with a UPFC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.828-829
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• 2011

This paper performs a comparison analysis of two types of HVDC system in Jeju power system. A traditional HVDC transmission system had been composed of line commutated converter based on thyristors and the development of semiconductors enables to apply voltage source converter using IGBTs. The detailed parameters of Jeju power system were considered to make a similar condition with real system in real time digital simulator. Two types of HVDC transmission system were modeled and simulated to compare their characteristics in Jeju power system. The simulation results demonstrate that the VSC-HVDC system has more stable performance due to the fast response speed than LCC-HVDC when the transmission capacity was fluctuated.

• 대한기계학회논문집A
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• 제20권5호
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• pp.1426-1435
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• 1996

In this paper. a network theory for generaltransmission systme was extended considering the direction of power flow. Also, a modified network model was suggested for a node with 4 shafts in order to verify the power flow. Based on the extended network theory, a simulation program was developed to analyze a hydro-mecaanical tranmission(HMT) system consistion of two hydrostatic pump motors, severeal planetary gear trains steer differential gear. The simulation result showed that the extendednotwork analysis program develped can predict the power circulation as well as the magnitude of torque and speed for each transmission element and can be used design tool for genaral power transmission system.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1759-1764
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• 2015

Glow corona is a kind of streamer-free corona that can suppress upward leaders in transmission lines. Thus, it has good application potential in lightning protection. This paper investigates its corona characteristics. The suppression characteristic of glow corona on streamer is studied in air gap under negative DC voltage by wrapping thin wires on the electrode. The effect of thin wire winding patterns on the gap breakdown voltage is analyzed. Results are considered to be attributed to the inception condition of glow corona. Thus an inception test of glow corona is also conducted, and the inception voltage is obtained. Results show that the inception voltage decreases with short winding pitch. Thus an investigation on the inception of glow corona influenced by thin wire is conducted, and an influential factor is proposed to evaluate the influence. The inception regular of thin wire glow corona presented in this paper has certain reference value for the application of glow corona in transmission lines.