• Journal of Power Electronics
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• 제12권4호
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• pp.528-537
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• 2012

This paper presents an interleaved resonant converter with a parallel-series transformer connection in order to achieve ripple current reduction at the output capacitor, zero voltage turn-on for the active switches, zero current turn-off for the rectifier diodes, less voltage stress on the rectifier diodes, and less current stress on the transformer primary windings. The primary windings of the two transformers are connected in parallel in order to share the input current and to reduce the root-mean-square (rms) current on the primary windings. The secondary windings of the two transformers are connected in series in order to ensure that the transformer primary currents are balanced. A full-wave diode rectifier is used at the output side to clamp the voltage stress of the rectifier diode at the output voltage. Two circuit modules are operated with the interleaved PWM scheme so that the input and output ripple currents are reduced. Based on the resonant behavior, all of the active switches are turned on under zero voltage switching (ZVS), and the rectifier diodes are turned off under zero current switching (ZCS) if the operating switching frequency is less than the series resonant frequency. Finally, experiments with a 1kW prototype are described to verify the effectiveness of the proposed converter.

• 경제분석
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• 제26권4호
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• pp.65-97
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• 2020

본 논문의 목적은 우리나라 수출의 고용파급효과와 그 변화 요인을 상세히 분석하는 데 있다. 이를 위해 가장 최근에 공표된 World Input-Output Database (WIOD)의 2000년부터 2014년까지의 세계산업연관표와 사회경제계정을 이용하여 다지역산업연관 및 구조적 요인 분해 분석을 실시하였다. 주요 분석 결과는 다음과 같다. 첫째, 우리나라 수출에 체화된 고용은 지속적으로 증가하였고, 우리나라 고용의 수출 의존도 역시 상승 추세를 보였다. 그러나 부가가치 수출의 고용유발계수는 전반적으로 하락하는 것으로 나타났다. 둘째, 우리나라 수출에 체화된 고용의 상당 부분은 중국, 미국, RoW(Rest of the World)의 최종수요에 기인한 것으로 분석되었다. 셋째, 우리나라 수출에 체화된 고용의 증대에 가장 큰 영향을 준 요인은 해외 최종수요의 변화 요인이었다. 이러한 실증분석 결과에 기초하여 우리나라의 국내 고용 확대를 위한 의미 있는 정책적 시사점을 논의하였다.

• 한국경제지리학회지
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• 제13권4호
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• pp.584-600
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• 2010

본 연구는 미국 동부 지역의 두 고속도로 회랑지대, I-95와 I-85 일대의 지식 기반 서비스업의 고용변화를 확장된 shift-share 분석을 통해 살펴보고 있다. 지식 기반 서비스업으로 선정된 산업은 금융, 보험, 비즈니스 서비스와 의료 산업이며 1977년부터 1990년, 1990년부터 2005년까지의 기간 동안의 대도시 지역이 연구 대상이다. 1977년부터 1990년 사이에는 생산량과 노동 생산성 측면에서 두 지역 모두 주변 지역 및 국가 전체 평균보다 월등한 성장세를 보였다. 그러나 1990년에서 2005년 사이에는 산업별 차이가 있었지만 평균에 미치지 못하는 성장 속도를 보이는 경우가 많이 나타났다. 또한 지리적으로 인접해 있거나 동일한 회랑지대에 위치한 대도시들도 유사한 고용 변화 패턴을 보이지는 않는다는 것이 밝혀졌다.

• 한국통신학회논문지
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• 제11권3호
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• pp.164-171
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• 1986

본 논문에서는 워크스테이션이 갖추어야할 기능을 분석한 결과를 바탕으로 시스팀설계 개념을 제시하고 있다. 워크스테이션은 입출력의 생산성 향상을 위하여 빠른 응답속도와 강력한 표시기능을 보유하여야 하며 이식성이 높고 기능 변경추가가 용이한 소프트웨어 구성과 효율적인 자원공유가 가능하도록 설계되어야 한다.

• Journal of Power Electronics
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• 제14권1호
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• pp.22-29
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• 2014

Current sharing between modules in a converter parallel operation is very important for the reliability of the system. This paper proposes an improved droop method that can effectively improve current sharing accuracy. The proposed method adaptively adjusts the output voltage set-point of each module according to the current set-points. Unlike conventional droop control, modules share a signal line to communicate with each other. Nevertheless, since signals are simple and in digital form, the complexity of the circuitry is much less and noise immunity is much better than those of conventional methods utilizing communication. The operation principle and design procedure of the proposed method are described in detail. Results of the experiment on two boost converters operating in parallel under the specification of a TFT LCD TV panel power supply verify the validity of the proposed scheme.

• ETRI Journal
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• 제40권3호
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• pp.337-346
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• 2018

In this paper, we propose a grant-aware (GA) scheduling algorithm that can provide higher throughput and lower latency than a conventional dual round-robin matching (DRRM) method. In our proposed GA algorithm, when an output receives requests from different inputs, the output not only sends a grant to the selected input, but also sends a grant indicator to all the other inputs to share the grant information. This allows the inputs to skip the granted outputs in their input arbiters in the next iteration. Simulation results using OPNET show that the proposed algorithm provides a maximum 3% higher throughput with approximately 31% less queuing delay than DRRM.

• 기술사
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• 제42권5호
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• pp.41-45
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• 2009

The last century of lighting has been dominated by incandescent, fluorescent and high-intensity discharge(HID)light sources. In the late 1970's, after green LEDs were invented, Dr. Ching Tang at Eastman Kodak discovered that sending an electrical impulse through carbon compound caused such material glow. Present day LED commercial packages have reached 100 lm/W, comparable to the efficacies of fluorescent and certain HID lamps. LED products available today are market as "Green-Industry" but actually low light output compared to typical light sources. The combination of high price and low light output make them a poor replacement for current technology. It is very important to compare new LED products to the most efficient conventional technology that could be used for any specific application. As LED technology advances, costs decrease, and efficiency improves, LEDs will build market share in the general illumination market.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.330-334
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• 2004

A new SEPIC-Flyback converter is proposed. The proposed converter is the integration of SEPIC and Flyback converter. Not only SEPIC output but also Flyback output could be fully regulated by constant frequency PWM control. Merged SEPIC and Flyback topology can share the transformer and power MOSFET. When the switch turns on, one topology operates via capacitive energy transfer. The other topology acts as inductive energy transfer while the switch is off. So, it can increase power density per one cycle. The experimental result is presented and verified.

• 한국멀티미디어학회논문지
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• 제9권6호
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• pp.720-727
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• 2006

In this paper, we propose a method which allows the SuperSQL query processor to share as much code as possible among various, generators, each of which is responsible for the output of a certain medium. SuperSQL is an enhanced query-processing system that converts database records into a variety of formats such as XML, HTML, PDF and etc. However, the existing SuperSQL media generator would require creation of a different processor for each medium, causing duplicated development cost. This research makes three main contributions: First, it analyzes the structures of various media, examining any possibility of integration based on their common structure. Second, it also facilitates the addition of a new output media generator by separating constructors and decorators from each medium. Last, it provides an integrated user interface to each media by method of the Media Abstraction Table Concept. We also show the performance and feasibility of our system using experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.90-94
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• 1998

The parallel inverter is popularly used because of its fault-tolerance capability, high-current outputs at constant voltages and system modularity. The conventional parallel inverter usually employes active and reactive power control or frequency and voltage droop control. However, these approaches have the disadvantages that the response time of parallel inverter control is slow against load and system parameter variation to calculate active, reactive power, frequency and voltage. This paper describes a novel control scheme for power equalization in parallel connected inverter. The proposed scheme has a fast power balance control response, a simplicity of implementation, and inherent peak current limiting capability since it employes a instantaneous current/voltage control with output voltage and current balance and output voltage regulation. A design procedure for the proposed parallel inverter controller is presented. Futhermore, the proposed control scheme is verified through the simulation in various cases such as the system parameter variation, the control parameter variation and the nonlinear load condition.