• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1705-1711
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• 2017

This paper analyzes the impact of DRA (Demand Response Aggregator) on market power when competing with power generation companies (Gencos) in the electricity market. If congestion occurs in the transmission line, the strategic choice of the power generation company increases exercise of market power. DRA's strategic reduction of power load impacts the strategy of Gencos, which in turn affects the outcome of the load reduction. As the strategy of Gencos changes according to the location of the congested transmission line, the impact on the market depends on the relative location of the congested line and the DRA.

• Journal of Power Electronics
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• v.19 no.3
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• pp.637-644
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• 2019

Wireless power transfer (WPT) technology with various transfer mechanisms such as inductive coupling, magnetic resonance and capacitive coupling is being widely researched. Until now, power transfer efficiency (PTE) and power transfer capability (PTC) have been the primary concerns for designing and developing WPT systems. Therefore, a lot of studies have been documented to improve PTE and PTC. However, power consumption in the standby mode, also defined as the no-load mode, has been rarely studied. Recently, since the number of WPT products has been gradually increasing, it is necessary to develop techniques for reducing the standby power consumption of WPT systems. This paper investigates the standby power consumption of commercial WPT products. Moreover, a standby power reduction technique for WPT systems via magnetic resonance coupling (MRC) with a parallel resonance type resonator is proposed. To achieve a further standby power reduction, the voltage control of an AC/DC travel adapter is also adopted. The operational principles and characteristics are described and verified with simulation and experimental results. The proposed method greatly reduces the standby power consumption of a WPT system via MRC from 2.03 W to 0.19 W.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.3
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• pp.1-8
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• 2008

Effects of annealing process in a reduction ambient on thermoelectric properties of the $(Bi,Sb)_{2}Te_3$ thin films prepared by thermal evaporation have been investigated. With annealing at $300^{\circ}C$ for 2 hrs in a reduction ambient(50% $H_2$+50% Ar), the crystallinity of the $(Bi,Sb)_{2}Te_3$ thin films were substantially improved with remarkable increase in the grain size. Seebeck coefficients of the $(Bi,Sb)_{2}Te_3$ thin films increased from$\sim90{\mu}V/K$ to $\sim180{\mu}V/K$ with annealing in the reduction ambient due to decrease in the hole concentration. Power factors of the $(Bi,Sb)_{2}Te_3$ thin films were remarkably improved for $5\sim16$ times with annealing in the reduction atmosphere. After annealing in the reduction ambient, a $(Bi,Sb)_{2}Te_3$ evaporated film exhibited a maximum power factor of $18.6\times10^{-4}W/K^{2}-m$.

• The Korean Journal of Health Service Management
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• v.10 no.2
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• pp.49-58
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• 2016

Objectives : The purpose of this study was to find factors affecting the cost-reduction practice of clinical nurses. Methods : The Data were collected from Feb. 25, to Mar. 15, 2015.the Total subjects were 201 nurses working in secondary-care hospitals located in Busan Results : The Meaningful variables that explain the cost-reduction practice in clinical nurses were psychological ownership, religion, and marital status in that order. Total explanation power was 22.1.% and psychological ownership has most explanation power. Conclusions : Psychological ownership and economic consciousness need to improve to develop cost-reduction practices. Additionally, nurses with and low concern about finances need to receive financial-related education.

• Journal of Environmental Science International
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• v.29 no.7
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• pp.729-737
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• 2020

This study estimates the greenhouse gas (GHG) emissions reduction resulting from photovoltaic and wind power technologies using a bottom-up approach for an indirect emission source (scope 2) in South Korea. To estimate GHG reductions from photovoltaic and wind power activities under standard operating conditions, methodologies are derived from the 2006 IPCC guidelines for national GHG inventories and the guidelines for local government greenhouse inventories of Korea published in 2016. Indirect emission factors for electricity are obtained from the 2011 Korea Power Exchange. The total annual GHG reduction from photovoltaic power (23,000 tons CO_2eq) and wind power (30,000 tons CO_2eq) was estimated to be 53,000 tons CO_2eq. The estimation of individual GHGs showed that the largest component is carbon dioxide, accounting for up to 99% of the total GHG. The results of estimation from photovoltaic and wind power were 63.60% and 80.22% of installed capacity, respectively. The annual average GHG reductions from photovoltaic and wind power per year per unit installed capacity (MW) were estimated as 549 tons CO_2eq/yr·MW and 647 tons CO_2eq/yr·MW, respectively. Finally, the results showed that the level of GHG reduction per year per installed capacity of photovoltaic and wind power is 62% and 42% compared to the CDM project, respectively.

• Journal of Convergence Society for SMB
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• v.1 no.1
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• pp.55-65
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• 2011

Due to the rapid advance of IT technologies such as mobile communication, sensor network, wearable computer, and so on, the needs of embedded software has increased. In those domain areas, the development of low-power embedded software is one of critical issues to enhance servicability of the system because almost embedded system depends on battery-based power supply system. Therefore this paper identifies the factors that can reduce the power consumption in embedded software operation, and proposes the method that how to handle the factors in software development process. Even though the existing and general studies about power reduction has been performed with code-based analysis, this analysis approach can lead reworks when the requirement for power consumption was not met. Our proposed techniques will support the power reduction in embedded software development process whenever the code was not developed. Our proposed process for lop-power embedded software development can gives the high quality in power-related serviceability.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.472-474
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• 2008

According to the development of power switching device technology, the power conversion system is used from the small electric power units to the large industrial instruments. These instruments are operated as harmonic sources in the grid and the harmonics cause zero sequence harmonics in the neutral line. To reduce zero sequence harmonics, the zigzag transformer is used conventionally. But the zigzag transformer can reduce only 60~70% of harmonics. In this paper, hybrid power filter for zero sequence harmonics reduction and the harmonic detection method are proposed.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.8
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• pp.399-404
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• 2000

This paper presents new algorithms equivalencing large-scale power systems. Generators are identified to the coherent groups according to the relation factors, which represent the relative coupling degree between the generators. While the groups are identified, participation numbers, which are the measure of the relative participation of the generators in the group, are obtained. All generators and controllers in the group are weighted by participation numbers and aggregated to construct a dynamic equivalent. The proposed algorithms are applied to a 272-machine Korea Electric Power Corporation (KEPCO)'s system. The enclosed results indicate the accuracy and usefulness of the algorithms.

• ETRI Journal
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• v.34 no.5
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• pp.727-733
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• 2012

This paper demonstrates a new driving scheme that allows reducing the supply voltage of data drivers for low-power active matrix organic light-emitting diode (AMOLED) displays. The proposed technique drives down the data voltage range by 50%, which subsequently diminishes in the peak power consumption of data drivers at the full white pattern by 75%. Because the gate voltage of a driving thin film transistor covers the same range as a conventional driving scheme by means of a level-shifting scheme, the low-data supply scheme achieves the equivalent dynamic range of OLED currents. The average power consumption of data drivers is reduced by 60% over 24 test images, and power consumption is kept below 25%.

• Journal of Power Electronics
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• v.9 no.2
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• pp.259-266
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• 2009

In order to increase the power density of power converters, reduction of the switching losses at high-frequency switching conditions is one of the most important issues. This paper presents a new gate drive circuit that enables the reduction of switching losses in both the Power MOSFET and the IGBT. A distinctive feature of this method is that both the turn-on loss and the turn-off loss are decreased simultaneously without using a conventional ZVS circuit, such as the quasi-resonant adjunctive circuit. Experimental results of the switching loss of both the Power MOSFET and the IGBT are shown. In addition, an energy recovery circuit suitable for use in IGBTs that can be realized by modifying the proposed gate drive circuit is also proposed. The effectiveness of both the proposed circuits was confirmed experimentally by the buck-chopper circuit.