• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.22-24
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• 2006

The installations of power quality monitoring system have increased drastically over the past several decades. These systems have been effectively used to monitor, analyze and diagnose the conditions of power system, and furthermore can be used to improve the present asset maintenance policy, scheduled (time-based) method, into the advanced, cost-effective and labor-effective maintenance methods, such as condition-based maintenance, predictive maintenance and reliability centered maintenance. As an approach to this, this paper introduces the statistical methods, three kinds of control charts (Shewhart chart, CUSUM chart and EWMA chart), and discusses the applicability of these methods to recognize the changing trends of power quality indices and to estimate the system's condition, using Matlab.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.207-209
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• 2001

Intensive competition in the electricity market and demand for higher quality service force the utilities to change their strategies in setting price and quality combination. As cost-up by homogeneously enhancing the electricity service quality may reduce their competitiveness, differential service is to be taken into consideration. Priority Service, which provides customers with a selection of service options at a range of prices and reliability for all or portions of their loads, has drawn attention from utilities in an increasingly competitive environment. Priority Service is to enlarge service options for customers who have diverse needs for supply reliability. This paper in the light of this point reviews differentiated strategy of power quality in the U.S.A.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1064-1070
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• 2007

This paper presents a grid-interactive current controlled voltage source inverter (CCVSI) with uniterruptible power supply (UPS), which uses an inner current control loop (polarized ramp time (PRT)) and outer feedback control loops to improve grid power quality and UPS. To reduce the complexity, cost and number of power conversions, which results in higher efficiency, a single stage CCVSI is used. The operation of this system could be divided into the power quality control (PQC) state mode and the UPS state mode. In PQC mode, the system operated to compensate the reactive power demand by nonlinear load or variation in load. In UPS mode. the system is controlled to provide a sinusoidal voltage at the rated value for the load when the gird fail. To verify the proposed system, a comprehensive evaluation with theoretical analysis, simulation and experimental results for 1KVA load capacity is presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4855-4862
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• 2015

This paper proposes low price power component measurement and record system for preventing electrical safety accident and supporting accident cause analysis by periodically monitoring and recording the operation status of electrical equipments. The proposed system was designed by mainly using parts to measure accurate power component but reduce cost. Especially, low cost and high effectiveness system implementation was possible by using MAXIM 78M6631 to calculate power components in the definition of IEEE Standard 1459-2010 related power quality. The measurement performance of the developed system is tested by using standard devices such as YOKOGAWA power analyzer WT1600. The test results showed that accuracy of the developed system is less than 0.5 % and the developed system is tested in a real area to verify the operation reliability and remote monitoring performance of the system over 6 months.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.5
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• pp.238-246
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• 2002

Utilities are trying to install the equipment of high quality to avoid deterioration of supply reliability. In addition, many sectionalizing switches which can decrease the total outage value for a fault are installed for the same reason. Therefore, utilities are interested in stun dards and criteria for installing switches to optimize the total cost on distribution systems. The affect of sectionalizing switches installed on distribution feeder is gradually decreased because the failure rate on distribution feeder is decreased. Also the automation for distribution systems is widely applied for the efficient operation. Therefore, the renewal for installation standards of sectionalizing switches Is required to reflect the current operation situation. The variable data is used to consider the KEPCO's real situation of distribution feeder as follows; the feeder capacity, connecting rate, feeder length, failure rate of distribution feeder, the failure rate of switches, perception time of feeder fault, the restoration time for a faulted section, the transfer time to other feeders, and the switching time. In this study, We propose equations which can determine the number of sectionalizing switches for minimizing the outage and switch installation cost.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.14-20
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• 1997

Due to several advantages of Pulse Width Modulated(PWM) Converter, such as unity power factor with low-harmonics and energy regeneration, PWM converter has been widely used in industrial application. In every application of energy conversion equipment, the design and implementation must be carried out considering performance and cost. High quality with low cost is the best choice for energy conversion equipment. High dc link voltage can reduce inverter and motor side losses and system dimension compare to low dc link voltage. Analog controller can make PWM converter cheaper without considerable degradation of the performance than digital controller. This paper shows the simplified analog controller-for 600V dc link voltage using stationary reference frame control and the simulation results.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.531-534
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• 2005

This paper presents a new data line sharing technique for TFT-LCD panels. This technique reduces the number of data driver IC's to half by having two adjacent pixels share the same data line. This in turn doubles the number of gate lines, which are integrated directly on the glass substrate of amorphous silicon for further cost reduction and more compactness. The proposed technique with new pixel array structure was applied to 15.4 inch WXGA TFT-LCD panels and has proven that the number of driver IC's were halved with nearly 41% circuit cost reduction and 5.3% reduction in power consumption without degrading the image quality.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.535-538
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• 2000

There are several electricity applied sterilizers such as sterilizer with high frequency sterilizer with ozone sterilizer with high voltage and so on Those sterilizers feature "because there is no chemical process there is no secondly environmental pollution" At the power conversion part ZVS and ZCS methods have been used that it results in reduced switching loss miniaturized size and lightened weight, Besides the current in the device is smaller than that of existing method. Thus it is expected that the cost of sterilization process when quality of the device is measured by power consumption will be reduced.e reduced.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.237-240
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• 2001

There are several electricity applied sterilizers such as sterilizer with high frequency, sterilizer with ozone, sterilizer with high voltage, and so on. Those sterilizers feature “because there is no chemical process, there is no secondly environmental pollution” At the power conversion part, AVS and ZCS methods have been used that it results in reduced switching loss, miniaturized size, and lightened weight. Besides, the current in the device is smaller than that of existing method. Thus, it is expected that the cost of sterilization process, when quality of the device is measured by power consumption, will be reduced.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.8
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• pp.82-89
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• 2014

The industrial products to use single phase inverter are raised the necessity of power quality improvement, such as AC Motor Driver, Lighting, Renewable energy power converter. Also, it is increasing that applied the single phase multilevel inverter for high quality power at renewable energy power converter. Especially, the photovoltaic multilevel inverters have at least more than two DC_Link and more than one DC/DC Converter. This paper proposes a triple output DC/DC Converter with one switch for photovoltaic multilevel inverter. The proposed converter has advantages of low cost and volume because it has one switch. The operation principle of the converter is analyzed and verified. A prototype is implemented to verify of the proposed converter.