• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.270-274
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• 2005

The human beings have increased concern about Energy saving and alternative energy. The power demand has increased the growth of industry and the improvement of life. We have to explore alternate energy sources and utilize effectively domestic resources. The lighting equipments developed Energy saving by using an electric ballast. The load installation should be promoted to rational power management, according to the network, inteligent, and high-function. Therefore, this paper has studied the method of energy saving and consulting.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.398-401
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• 2005

This paper presents a user-friendly application for voltage sag analysis and effective visualization for analysis date. This developed tool provides basic functions for voltage sag analysis such as load flow analysis, short circuit analysis and determination of vulnerability of sensitive equipments. Particularly it has the ability to visualize analysis results effectively using computer graphic and animation. In order to give the real sense, analysis results are displayed with geographical information in an intuitive and rapid manner. The developed voltage sag simulator is applied to the Jeju-Island power system in order to show its capabilities.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.6
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• pp.1011-1016
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• 2010

It is an important issue to electric power system operations that it can reliably supply large-capacity power to consumption area as due to increasing power demand growth. For this purpose, The FACTS equipment based on Power IT technology with the existing mechanical compensators has been applied to power system. Therefore we suggest on this paper that a plan for coordination control of multiple power compensation equipment in order to increase the utilization of each facility and secure operation margin capacity. As the result of simulation, it is possible to cope actively with a suddenly changed power system. This helps greatly for the voltage stability and supply reliability in a suddenly changed power system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.5
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• pp.958-965
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• 2007

The spreaders on container cranes are usually controlled to stop at the same time as their trolleys are stopped. Despite the use of adequate control systems, however, the spreaders usually have comparatively large sway movements, due to their suspension from the trolleys through cables. It is, therefore, important to accurately measure the attitudes of the spreaders, in order to suppress such sways by means of secondary control. Until now, most of conventional anti sway control systems focus on the direct control of the movements of trolleys. which seems not suitable to speed up the entire process - loading and unloading of containers. In this paper, we suggest a new anti sway control system: By using extra equipments - two propellers to suppress the sway and a PSD camera to measure the spreader's attitude - installed on the spreader and the trolley. the sway of the suspended load j, considerably suppressed. The effectiveness of the proposed scheme is verified by the computer simulation and experiment with the miniature of the container crane system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.6
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• pp.294-302
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• 2005

PV system's islanding occurs when the uitilty grid is removed but local sources continue to operate and provide power to local loads. Islanding is one of the serious problems in an electric power system connected with dispersed power sources. Also, this can present safety hazards and the possibility of damage to other electric equipments. If the real and reactive power of RLC load and PV system are closely matched, islanding detection by passive methods becomes difficult. This paper shows the simulation and comparision for the previous active methods and novel islanding detection method using frequency drift is proposed for grid-connected PV system.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.48-53
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• 2014

This study is analyzed for electrical fire danger by electric equipments through surveys of stable owners and the field investigation at 64 stable. Also, an experiment is performed to analyze the thermal characteristics of 4 types electric wiring according to the number of operating halogen warm lamp group and automatic waterer group in Beon-young stable in the Cheongwon location. The survey is done to investigate the occurrence of electrical fire, electric equipment, causes and dangerous equipment. As a result, halogen warm lamp group and automatic waterer group are found to have dangerous loads. In the field investigation, the mode of load capacity of the halogen warm lamp group and automatic waterer group was investigated. The mode of load capacity of halogen warm lamp group (over 3 years) is found 17A and that of the auto waterer group (10 years) is 16A. In this experiment, the halogen warm lamp group aged at least 3 years showed $109^{\circ}C$ while that aged less than 1 year appeared $83^{\circ}C$, showing the max gap of $26^{\circ}C$. The automatic waterer group aged 10 years showed $90^{\circ}C$ while that aged less than 1 year appeared $68^{\circ}C$, showing the max gap of $22^{\circ}C$. These findings indicate that the mode of load capacity needs to be considered in selecting and installing wiring for the electric equipment construction of halogen warm lamp group and automatic waterer group in stable.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.4
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• pp.384-394
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• 1999

This paper deals with a fixed frequency full-bridge inverter type DC-DC high-power converter with high frequency high voltage(HFHV) transformer-coupled stage, which operates under quasi-resonant ZVS transition priciple in spite of a wide PWM-based voltage regulation processing and largely-changed load conditions. This multi-resonant(MR) converter topology is composed of a series capacitor-connected parallel resonant tank which makes the most of parasitic circuit reactive components of HFHV transformer and two additional quasi-resonant pole circuits incorporated into the bridge legs. The soft-switching operation and practical efficacy of this new converter circuit using the latest IGBTs are actually ascertained through 50kV trially-produced converter system operating using 20kHz/30kHz high voltage(HV) transformers which is applied for driving the diagnostic HV X-ray tube load in medical equipments. It is proved from a practical point of view that the switching losses of IGBTs and their electrical dynamic stresses relating to EMI noise can be considerably reduced under a high frequency(HF) switching-based phase-shift PWM control process for a load setting requirements.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.1-8
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• 2010

The ultrafashionable machinery that require high quality electricity power has been daily come into being. Because domestic power system has been larger and more complicated in accordance with raising power demand by power market requirement. Because of these power market situations, The FACTS (Flexible AC Transmission System) which is power transmission system for the next generation to meet flexible supply the power and reliability has been applied. If they, compensators and FACTS, are used inter-efficiently in range that does not affect the stability and a badly influence the security, they might be increase in the voltage stability of system, supply reliability and also achieve the voltage control in a suddenly changed power system. Therefore we describe and suggest on this treatise that a plan for coordination control between UPFC, Shunt elements (Sh. Capacitors & Sh. Reactors) among compensators and also describe the method to keep or control the voltage of power system in allowable ranges. The method follows that, we used characteristics of each equipment, UPFC would be also settled to keep the identified voltage range in change of load bus, Shunt elements also would be settled to supply the reactive power shortage in out of operating range of UPFC to cope actively with change of the power system. As the result of simulation, it is possible to keep the load bus voltage in limited range in spite of broad load range condition. This helps greatly for the improvements of supply reliability and voltage stability.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.114-123
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• 2005

A nonlinear speed control of a PMSM using a sequential parameter auto-tuning algorithm for servo equipments is presented. The nonlinear control scheme gives an undesirable output performance under the mismatch of the system parameters and load conditions. Recently, to improve the performance, an adaptive linearization scheme, a sliding mode control and an observer-based technique have been reported. Although a good performance can be obtained, the performance is not satisfactory any more under specific conditions such as a large inertia variation, a fast speed transient or an increased sampling time. The simultaneous estimation of principal parameters giving a direct influence on speed dynamics is generally not simple. To overcome this problem, a a sequential parameter auto-tuning algorithm at start-up is proposed, where dominant parameters are estimated in a prescribed regular sequence based on the method that one parameter is estimated during each interval. The proposed scheme is implemented on a PMSM using DSP TMS320C31 and the effectiveness is verified through simulations and experiments.

• Journal of the Korean Solar Energy Society
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• v.26 no.4
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• pp.17-23
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• 2006

This paper proposes a novel active frequency drift (AFD) method for the islanding prevention of grid-connected photovoltaic inverter. To detect the islanding phenomenon of grid-connected photovoltaic (PV) inverters concerning about the safety hazards and the damage to other electric equipments, many kinds of anti-islanding methods have been presented. Among them, AFD method using chopping fraction enables the islanding detection to drift up (or down) the frequency of the voltage during the islanding situation. In this paper, injecting the periodic zero current into the basic AFD method is proposed. This proposed method shows the analytical design value of cf to meet the test procedure of IEEE Std. 1547 with various load conditions. Detection of islanding is verified using simulation tool PSIM.