• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.34-37
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• 2001

This paper evaluate reliability indices of a part of transmission network of KEPCO system. Quantitative evaluation of transmission system reliability is very important because successful operation of an electric power system in the deregulated electricity market depends on transmission system reliability management. Monte Carlo methods are often preferable, when complex operating conditions are involved and/or the number of sever events is relatively large. Monte Carlo simulation methods and CMELDC(CoMposite power system Effective Load Duration Curve) were used in this paper.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.476-480
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• 2003

This paper presents an effective method to analyze the dynamic characteristics for the shilling transients of power transmission system using the multibody dynamics, which is composed of subsystem equation, subsystem assemble, and the self-determining technique for the system degree of freedom. Using the advantages of multibody dynamics, the proposed method can be used easily for mathematical models of mechanical systems, such as a power transmission, compared with newtonian method. With this theory, dynamic simulation program was developed. The program can be used to verify system performances, transient phenomena, and other dynamic problems. The simulation of a target system was presented, and its validity was attained by being compared with the previous analysis using newtonian method.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.62-66
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• 2003

In recent, the importance and necessity of some studies on reliability evaluation of grid comes from the recent black-out accidents occurred in the world. The quantity evaluation of transmission system reliability is very important under competitive electricity environment. The reason is that the successful operation of electric power under the deregulated electricity market depends on transmission system reliability management. This paper introduces features and operation modes of the Transmission Reliability Evaluation for Large-Scale Systems(TRELSS) Version 5_1, a program made in EPRI, for assessing reliability indices of composite power system. The package accesses not only bulk but also buses indices for reliability evaluation of composite powers system. The characteristics of the TRELSS program are illustrated by the case studies using the IEEE 25buses system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2227-2235
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• 2009

This paper describes the system configuration and measured performances of a wireless power transmission system which utilizes microwave. The technically final target of this system is to provide DC power to various mobile terminals within limited spaces such as buildings, conference rooms, and so on. The prototype system is built using in-house designed and fabricated circuits such as microwave oscillator, high power amplifier, microstrip patch antenna, low pass filter, and detector/rectifier. The fixed RF power of 29.3dBm at 2.4GHz is produced from the high power amplifier and transmitted through the transmitting antenna, while the received RF power at the receiving antenna is transformed into DC power through the detector/rectifier. The measured change of DC voltage according to the distance between transmitting and receiving antenna is described.

• Journal of Biosystems Engineering
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• v.43 no.1
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• pp.1-13
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• 2018

Purpose: The development of compact tractors that can be used in dry fields, greenhouses, and orchards for pest control, weeding, transportation, and harvesting is necessary. The development and performance evaluation of power transmission units are very important when it comes to tractor development. This study evaluates the performance of a driving power transmission unit of a 50 kW multi-purpose narrow tractor. Methods: The performance of the transmission and forward-reverse clutch, which are the main components of the driving power transmission unit of multi-purpose narrow tractors, was evaluated herein. The transmission performance was evaluated in terms of power transmission efficiency, noise, and axle load, while the forward-reverse clutch performance was evaluated in terms of durability. The transmission's power transmission efficiency accounts for the measurement of transmission losses, which occur in the transmission's gear, bearing, and oil seal. The motor's power was input in the transmission's input shaft. The rotational speed and torque were measured in the final output shaft. The noise was measured at each speed level after installing a microphone on the left, right, and upper sides. The axle load test was performed through a continuous equilibrium load test, in which a constant load was continuously applied. The forward-reverse clutch performance was calculated using the engine torque to axle torque ratio with the assembled engine and transmission. Results: The loss of power in the transmission efficiency test of the driving power unit was 6.0-9.7 kW based on all gear steps. This loss of horsepower was equal to 11-18% of the input power (52 kW). The transmission efficiency of the driving power unit was 81.5-89.0%. The noise of the driving power unit was 50-57 dB at 800 rpm, 70-77 dB at 1600 rpm, and 76-83 dB at 2400 rpm. The axle load test verified that the input torque and axle revolutions were constant. The results of the forward-reverse clutch performance test revealed that hydraulic pressure and torque changes were stably maintained when moving forward or backward, and its operation met the hydraulic design standards. Conclusions: When comprehensively examined, these research results were similar to the main driving power transmission systems from USA and Japan in terms of performance. Based on these results, tractor prototypes are expected to be created and supplied to farmhouses after going through sufficient in-situ adaptability tests.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.551-559
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• 2008

Increase in power consumption can cause a serious stability problem of an electric power system without construction of new power plants or transmission lines. Also, it can generate large power loss of the system. In costly and environmentally effective manner to avoid constructing the new infrastructures such as power plants and transmission lines, etc, the distributed generation(DG) has paid great attentions so far as a solution for the above problem. Selection of optimal location and size of the DG is the necessary process to maintain the stability and reliability of existing system effectively. However, the systematic and cardinal rule for this issue is still open question. In this paper, the method to determine optimal location of the DG is proposed by considering power loss when the DG is connected to an electric power grid. Also, optimal size of not only the corresponding single DG but also the multi-DGs is determined with the proposed systematic approach. The IEEE benchmark 30-bus test system is analyzed to evaluate the feasibility and effectiveness of the proposed method.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.3
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• pp.365-371
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• 2019

Recently, the demonstration and research on the power transmission using high voltage DC such as HVDC(High Voltage DC), Smart Grid, DC transmission and distribution have been actively conducted. In order to control the power converter in high-voltage DC power transmission system, SMPS(Switching Modulation Power Supply) for power converter control using high-voltage DC input is essential. However, the demand for high-pressure SMPS is still low, so the development is not enough. In the low-output SMPS using the high-voltage input, it is difficult to achieve high efficiency due to the switching transient loss especially at light load. In this paper, we propose a new switching scheme for high power SMPS control for low output power. The proposed method can provide better efficiency increase effect in the light load region compared to the existing PWM method. To verify the feasibility of the proposed method, a 40 W SMPS for HVDC MMC(Modulation Multi-level Converter) was designed and verified by simulation.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.243-244
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• 2015

Power system has been improved during for a long time by customers demand. Power suppliers has researched the power system component for more electricity transmission. One of the research is apply the thermal conductors in new cable. The operational temperature of thermal conductors is higher than normal aluminum that thermal conductor is composed of aluminum, Zr(zirconium) and etc. Increase of operational temperature is growth of the transmission capability. Power suppliers was concerned about the increase of operation temperature by thermal conductors. Therefore, the thermal conductor has the possibility that expanded application in power system. In this paper analysed effect of thermal conductor in power distribution system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.3
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• pp.165-172
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• 2003

This paper presents an operation scheme to enhance the power system security by applying FACTS on Power systems. Three main generic types of FACTS devices are suggested an illustrated. Flow congestions over lines have been solved by controlling active power of series-compensated FACTS devices and low voltages at buses have been solved by controlling reactive power of shunt-compensated FACTS devices. Especially, Especially, UPFC has been applied in both line congestion and low voltages. Two kinds of indices which indicate the power system security level related to line flow and bus voltage are utilized in this paper. They have been minimized to enhance the power system security level through the iterative method and the sensitivity vector of security index is derived to determine the direction to minimum. The proposed algorithm has been tested on the IEEE 57-bus system with FACTS devices in a normal condition and a line-faulted contingency.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.201-203
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• 2006

This paper presents a graphical windows-based software for the education and training of the transmission network use of system charge. The developed simulator consist of the main module(MMI,GUI), the power flow module(PF), the power flow tracing module(PFT) and management of usage cost DB module(UCD). Each module has a separate graphical and interactive interfacing window. To have effective education for transmission network use of system charge, the developed simulator are provided with two power system analysis methods. Input data of power system can use the format of PSS/E input data. Also calculation of power flow tracing are provided with four methods such as "Felix Wu","Modified Felix Wu", "DCLF ICRP" and "Reverse MW mile". Results of calculation for usage cost are shown on the window through the table or chart. Therefore user can confirm the detailed differences of results from each calculation method.