• 전자공학회논문지
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• 제54권1호
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• pp.41-45
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• 2017

본 논문에서는 조합논리스템의 효율적인 다중출력스위칭함수 구성의 한 가지 방법을 제안하였다. 제안한 방법의 시간영역기반의 멀티플렉싱을 기반으로 공통다중종단노드확장논리결정도를 도출하여 최종 조합논리시스템의 다중출력스위칭함수를 구하므로 기존의 시간영역기반의 멀티플렉싱에 비해 최적화된 입력변수의 쌍과 출력변수 쌍을 상당히 줄일 수 있으며, 또한 코스트 면에서도 유리하다. 또한, 입출력단자 수의 감소, 회로구성의 간략화, 연산속도의 향상 등의 이점이 있으며 기존의 방법에 비해 좀 더 정규성과 확장성이 용이하다.

• Journal of Power Electronics
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• 제19권3호
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• pp.665-675
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• 2019

Renewable energy based on photovoltaic systems is beginning to play an important role to supply power to remote areas all over the world. Owing to the lower output voltage of photovoltaic arrays, high gain DC-DC converters with a high efficiency are required in practice. This paper presents a novel interleaved DC-DC boost converter with a high voltage gain, where the input terminal is interlaced in parallel and the output terminal is staggered in series (IPOSB). The IPOSB configuration can reduce input current ripples because two inductors are interlaced in parallel. The double output capacitors are charged in staggered parallel and discharged in series for the load. Therefore, IPOSB can attain a high step-up conversion and a lower output voltage ripple. In addtion, the output voltage can be automatically divided by two capacitors, without the need for extra sharing control methods. At the same time, the voltage stress of the power devices is lowered. The inrush current problem of capacitors is restrained by the inductor when compared with high gain converters with a switching-capacitor structure. The working principle and steady-state characteristics of the converter are analyzed in detail. The correctness of the theoretical analysis is verified by experimental results.

• 동력기계공학회지
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• 제7권1호
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• pp.74-81
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• 2003

A system identification is to estimate the mathematical model on the base of input output data and to measure the output in the presence of adequate input for the controlled system. In the traditional system control field, most identification problems have been thought as estimating the unknown modeling parameters on the assumption that the model structures are fixed. In the system identification, it is possible to estimate the true parameter values by the adjusted least squares method in the input output case of no observed noise, and it is possible to estimate the true parameter values by the total least squares method in the input output case with the observed noise. We suggest the adjusted least squares method as a consistent estimation method in the system identification in the case where there is observed noise only in the output. In this paper the adjusted least squares method has been developed from the least squares method and the efficiency of the estimating results was confirmed by the generating data with the computer simulations.

• 대한안전경영과학회지
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• 제9권5호
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• pp.125-133
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• 2007

Everyone knows how much the company business goal is achieved is the most important to all companies. In order to maximize the business performance, many companies have introduced a diversity of management innovation activities. The effect of business performance is important in the business activity, but an efficiency of output-to-input concept is significantly important. Each year, companies have managed the business through a sum of performance. In terms of the efficiency of business performance, the management is importantly managed. In the efficiency of business performance, there are the main items including the total assets, employees, and operating expenses as the input. As the output, there are the main items of sales, current term's net income. This study is intended to calculate the business efficiency through DEA analysis for companies' business performance, and to study in order for the efficiency of business performance to be considered when the companies establish the mid and long term business plan.

• 기술혁신연구
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• 제19권1호
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• pp.1-27
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• 2011

본 연구는 1984년부터 패널자료의 확보가 가능한 17개 OECD 국가를 표본으로 하여 R&D 생산성 및 효율성에 대한 실증분석을 통해 비교하고 우리나라의 수준과 특징을 살펴보고자 하였다. 이를 위해 그 성과를 산출(output) 측면과 성과(outcome) 측면으로 구분하고, 맘퀴스트 생산성지수와 자료포락분석방법을 활용하여 R&D경로단계별 생산성 및 효율성과 그 변화추이를 비교분석하였다. 우리나라는 R&D 투자 대비 산출 생산성은 매우 높은 반면, 평균효율성은 매우 낮게 나타났으며, 효율성의 시계열 변화추이를 보면 최초 지수 0.10에서 시작하여 최종 0.83까지 가파르게 상승하면서 주요 선진국들 수준에 도달하였다. R&D 산출 대비 생산성은 매우 낮으며, 통합 프런티어에 대한 효율성은 최초 지수 1.00에서 최종 0.057까지 주요 선진국들 수준으로 가파르게 하락하여 왔다. 그리고 상관분석을 통해 R&D 산출 대비 생산성이 곧 R&D 투자 대비 생산성을 가늠하는 지표가 될 수 있음을 보았다. 본 연구는 우리나라의 R&D 생산성 및 효율성 향상을 위해서는 R&D 투자 및 산출 증대의 노력이상으로 R&D 산출물의 활용 측면이 보다 강화되어야 하고 이를 위해 효과적인 기술확산 체계 구축, 기술금융시장환경 조성 및 사업화에 성공하기까지 실질적인 인큐베이팅 제공 등 전반적인 기술사업화 시스템의 혁신이 주요 과제임을 시사하고 있다.

• 산업경영시스템학회지
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• 제35권1호
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• pp.188-197
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• 2012

DEA 모델중 널리 사용되는 교차평가모델(cross efficiency model)은 가중치에 제한을 두지 않고 어떤 특정분야에 탁월한 성과를 내는 DMU(Decision Making Unit)보다는 보다 전반적인 분야에서 두각을 나타내는 DMU를 선발함으로써 많은 연구자들이 DEA문헌에서 적용하여 왔다. 본 연구에서는 이러한 교차평가모델이 실제에 있어서는 암묵적으로 고정 가중치를 사용한다는 것과 동일한 결과를 나타낸다는 것을 분석적으로 밝혔다(one input, multi output case). 또한 multi-input, multi-output case의 경우에도 overall performer의 cluster에 근접한 대다수 DMU의 경우에는 고정 가중치를 사용한 경우와 거의 차이가 없음을 보였다. 교차평가 모델에 적용된 변수의 가중치를 보다 명확히 함으로써 연구자들이 모델의 평가결과를 이해하는데 도움이 될 수 있을 것이다. 또한 교차 평가의 가중치 도식을 더 명확히 보여주기 위해 biplot을 제안한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.393-399
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• 1997

Single-phase and three-phase AC to DC power converters are becoming frequently used for high voltage/high power applications such as telecommunications. They often require input/output transformer isolation for safety, a unity input power factor for minimum reactive power, free input harmonic currents fed back to the AC Power distribution system and, finally, high efficiency and high power density for minimum weight and volume. The proposed boost converter for power factor correction (PFC) provides an unity input power factor, low harmonic distortion and high efficiency along with reduced volume and weight. Single-phase 220VAC input/380VDC 1KW output prototype is constructed and experimental results will be verified with those of PSpice simulation.

• Journal of information and communication convergence engineering
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• 제17권4호
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• pp.285-289
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• 2019

A 1.9-GHz linear CMOS power amplifier is presented. An adaptive bias circuit (ABC) that utilizes an AC ground to detect the power level of the input signal is proposed to enhance the linearity and efficiency of the power amplifier. The ABC utilizes the second harmonic component as the input to mitigate the distortion of the fundamental signal. The input power level of the ABC was detected at the AC ground located at the V_DD node of the power amplifier. The output of the ABC was fed into the inputs of the power stage. The input signal distortion was mitigated by detecting the input power level at the AC ground. The power amplifier was designed using a 180 nm RFCMOS process to evaluate the feasibility of the application of the proposed ABC in the power amplifier. The measured output power and power-added efficiency were improved by 1.7 dB and 2.9%, respectively.

• Journal of Power Electronics
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• 제17권5호
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• pp.1137-1149
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• 2017

In order to reduce the cost, improve the efficiency and simplify the complicated control of existing isolated LED drivers, an improved boundary conduction mode (BCM) Buck ac-dc light emitting diode (LED) driver with extended output voltage and low total harmonic distortion is proposed. With a coupled inductor winding and a stacked output, its output voltage can be elevated to a much higher value when compared to that of the conventional Buck ac-dc converter, without sacrificing the input harmonics and power factor. Therefore, the proposed Buck LED driver can meet the IEC61000-3-2 (Class C) limitation and has a low THD. The operating principle of the topology and the design methodology of the ac-dc LED driver are presented. A 150 W ac-dc prototype was built in the laboratory and it shows that the input current harmonics meet the lighting standard. In addition, the THD is less than 16% at a typical ac input. The peak efficiency is higher than 96.5% at a full load and a normal input.

• 대한안전경영과학회지
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• 제17권4호
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• pp.87-96
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• 2015

This study analyzed the safety management efficiency through input-oriented BCC Model using DEA by making of Models, in which this study selected the number of staff affiliated with the construction site, number of staff members on the construction team, and number of safety personnel as Input Factor, along with the number of disaster victims and zero-accident accomplished hours as output elements, targeting 40-or-so apartment building construction sites which are being built by 3 domestic construction companies. As a result of efficiency, it was 0.643, the number of efficient DMU was 4. In the aspect of returns to scale, 21 construction sites(52.5%) found to be in a state of increasing returns while 14 construction sites(35%) was in a state of Decreasing returns. The reason for inefficiency was found to lie in technical factors in case of 30 construction sites(75%). Lastly, inefficient DMU is in need of 38.9 % and 66% reduction in site personnel and safety personnel. Based on study results, the 29 construction sites accounting for 72.5% of DMU for safety management efficiency evaluation object turned out to do inefficient safety management that doesn't fit the size of each company.