• Composites Research
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• 제32권5호
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• pp.237-242
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• 2019

이 연구에서는 마이크로 그리드 패턴 표면을 갖는 탄소 분말이 첨가된 Poly-dimethylsiloxane (PDMS)를 사용하여 전기용량형 압력센서(Piezocapacitive Sensor)를 제작하였다. 탄소 분말과 그리드 패턴이 센서의 성능에 미치는 효과를 알아보기 위해 탄소 분말의 농도와 그리드 패턴의 밀도를 달리하여 여러 개의 센서를 제작하였다. 센서의 작동 범위와 민감도를 척도로 센서의 성능을 비교하였다.

• 전기학회논문지
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• 제66권7호
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• pp.1032-1038
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• 2017

Recently, regulation on carbon emissions has been strengthened according to the new climate change convention (COP21) held in Paris, and then Korea has decided to reduce CO2 emissions by 37% until 2030. As one of countermeasures, the government has energetically performed demonstration projects of island micro-grid including solar power, wind power and energy storage system. However, in order to smoothly introduce island micro-grid, it is a critical issue to carry out the economic evaluation for power utility aspect and independent power producer aspect. Therefore, this paper proposes economic evaluation algorithms of island micro-grid which are based on the present worth method, considering cost and benefit factors in the aspect of both sides. Firstly, in case of power utility this paper proposes algorithm to estimate a period of return on investment according to the introduction capacity of distributed generators replacing diesel generator. And also, in case of independent power producer, this paper proposes evaluation algorithm to estimate weighting factor of SMP and benefit rate based on break-even point related with cost and benefit. From a case study result on real island micro-grid model, it is confirmed that proposed algorithms are useful and practical for the economic evaluation of island micro-grid.

• 전력전자학회논문지
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• 제18권1호
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• pp.63-71
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• 2013

This paper describes the coordinated droop control method for stand-alone type DC micro-grid to improve reliability and utilization of distributed generations and energy storage. The stand-alone type DC micro-grid consists of several distributed generations such as a wind power generation, solar power and micro-turbine, and energy storage. The proposed method which is based on autonomous control method shows high reliability and stability through coordinated droop control of distributed generations and energy storage and also capability of battery management. The operation of stand-alone type DC micro-grid was analyzed using detail simulation model with PSCAD/EMTDC software. Based on simulation results, a hardware simulator was built and tested with commercially available components and performance of system was verified.

• 대한방사선기술학회지:방사선기술과학
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• 제41권2호
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• pp.149-155
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• 2018

Quantitative analysis was performed to confirm that moire artifact was removed without loss of image when using grid suppression software in the diagnosis of micro lesions. we showed that grid suppression images can be morphologically different from original images as they are significantly lower than those of the optimized grid in the similarity analysis with reference images in mammographic phantom images. We were confirmed that images of microcalcification with smaller signal than noise were lost because the pixel values of all lesions increased significantly after the grid suppression, The change in contrast using the NORMI 13 X-ray test phantom was reduced to 30% of the reference image, This result was significantly lower than the 90% when using the optimized grid. In conclusion, the use of grid suppression software in clinical images should be carefully considered because of the possibility of misdiagnosis due to micro lesion loss and morphological changes.

• 조명전기설비학회논문지
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• 제19권8호
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• pp.24-32
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• 2005

마이크로소스는 1[KW]${\sim}$수[MW] 사이의 전력을 공급하고, 기존의 대규모 발전설비보다 높은 신뢰도와 에너지 효율을 가지는 고품질의 전력을 공급할 수 있다. 이들은 크기가 작고 설치가 용이하여 빌딩, 산업체, 가정 등과 같은 수용가 측의 부하와 클러스터를 형성하여 마이크로그리드로 운전된다. 마이크로소스는 부하단의 전압 등의 전압품질을 제어하기 위하여 전압원형 인버터를 채용하고 있다. 본 논문에서는 다수의 마이크로소스가 계통에 연계되었을 때의 마이크로소스의 모델링 및 제어시스템의 특성에 관하여 연구하였다. 전력주파수 영역에서의 기본파 정상상태 인버터 모델을 이용한 마이크로소스의 EMTDC 모델을 개발하였으며, 이를 통해 마이크로소스의 제어시스템 파라미터에 따른 제어특성을 분석하였다. 컴퓨터 시뮬레이션을 통하여 제안된 모델의 효용성을 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.1112-1118
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• 2014

In island and backcountry areas, electrical power is usually supplied by diesel generators. It is difficult for small scale diesel generators to have an economy of scale owing to the usage of fossil fuels to produce electricity. Also, there is a problem of carbon dioxide emissions that brings some environmental pollution to the entire region of the area. For solving those, this paper proposes a design method of autonomous micro-grid to minimize the fossil fuels of diesel generator, which is composed of diesel generator, wind turbine, battery energy storage system and photovoltaic generation system. The proposed method was verified through computer simulation and micro-grid operation system.

• 조명전기설비학회논문지
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• 제23권10호
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• pp.52-58
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• 2009

본 논문에서는 마이크로그리드(Micro grid, MG)의 설계에서 필요로 되는 에너지저장장치(Energy storage system, ESS)의 최소설비용량을 산정할 수 있는 확률론적 방법론을 제시하였다. ESS기술은 아직까지 경제성 측면에서 매우 높은 설비비용이 필요로 되기 때문에 적정 설비규모를 산정하는 것과 MG의 안정적인 운영을 위해서 최소 설비용량에 대한 가이드라인의 제시가 필요로 된다. 본 논문에서 제시한 방법론은 Non-dispatchable 발전원 출력의 간헐성과 모든 발전기의 고장정지확률을 고려하여 MG가 자체적인 에너지 Self balancing을 유지할 수 있는 ESS의 최소설비용량을 산정할 수 있는 것을 특징으로 한다.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1328-1334
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• 2015

A new system for evaluating the voltage management errors of distribution equipment is presented in this paper. The main concept of the new system is to use real distribution live-line voltage to evaluate and correct the voltage measurement data from distribution equipment. This new approach is suitable for a new Distribution Management System (DMS) which has been developed for a distribution power system due to the connection of distributed generation growth. The data from distribution equipment that is installed at distribution lines must be accurate for the performance of the DMS. The proposed system is expected to provide a solution for voltage measurement accuracy assessment for the reliable and efficient operation of the DMS. An experimental study on actual distribution equipment verifies that this voltage measurement accuracy assessment system can assess and calibrate the voltage measurement data from distribution equipment installed at the distribution line.

• 전기학회논문지
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• 제66권3호
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• pp.486-492
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• 2017

In recent years, renewable energy sources have been mentioned as solution to environmental regulation and energy supply-demand. Energy storage systems are needed to mitigate the intermittent output characteristics of renewable energy sources and to operate micro grid efficiently using renewable energy generation systems. However, despite the necessity of energy storage system, this cannot secure the economical efficiency of the energy storage system by high initial cost. In this paper, a micro grid is constructed to supply electric power to industrial customers by using solar power generation system and energy storage system among renewable energy generation power sources and operated to improve energy independence. In the case study, we use photovoltaic system which is representative renewable energy generation system. Unlike conventional photovoltaic system, this system uses floating photovoltaic system with the advantage of having high output and no land area limitations. It is operated for the purpose of improving energy independence in the micro grid. In order to secure economical efficiency, the energy storage system operates a micro grid with a minimum capacity. Finally, this paper calculates the appropriate subsidy for the energy storage capacity.

• 대한방사선기술학회지:방사선기술과학
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• 제40권4호
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• pp.575-580
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• 2017

Moire artifact는 미세병변과 주파수 대역이 중첩되기 때문에 moire artifact를 제거하는 Image processing software를 사용할 경우 미세 병변의 손실을 가져올 수 있다. 본 연구에서는 SD(Sprague Dawley) Rat에 microcalcification과 microfracture와 같은 미세병변을 임의로 형성하여 영상화하고, reference 영상과 grid suppression software를 사용한 영상, optimizied grid 영상을 비교 분석하였다. 영상은 두 명의 영상의학과 전문의가 컨소시엄을 형성하여 판독하였고, 판독 결과 값은 McNemar's test 이용하여 평가하였다. 73개의 microcalcifications 중 Grid suppression후 13 cases에서, optimized grid를 사용한 영상은 3 cases에서 영상의 손실이 확인되어 Grid suppression후의 영상이 통계적으로 유의하게 영상 손실을 발생하고 있음을 보여주고 있다(p=0.021). 총 53개의 fracture line은 Grid suppression을 시행한 후 영상에서 19 cases가 영상의 손실을 보였고, optimized grid를 사용한 영상에서는 영상손실이 없는 것으로 판독되었다. 따라서 미세병변을 진단하는 영상에 있어 moire artifact를 제거하기 위한 grid suppression software 사용은 신중하게 고려되어야 할 것이다.