• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.951-958
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• 2019

For the power grid-connection of distributed generation, the output voltage of the distributed generation must be synchronized with the grid voltage before the grid-connection. In this paper, a vector control based synchronization algorithm was developed for grid linkage of three-phase inverters. A three-phase voltage inverter was designed and fabricated to verify the effectiveness of the developed algorithm. The main controller of the three-phase inverter was developed based on DSP, and the electrical level of the system was set to an electrical level that can be tested in the laboratory. Throughout the experiments, it was confirmed that the proposed algorithm could be used as a synchronization algorithm for grid-connection by showing that the output voltage of the three-phase inverter is synchronized with the grid voltage.

• KLA journal
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• v.52 no.8
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• pp.32-35
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• 2011

학교 교육과정에서 도서관 교육은 학습 내용과 학습 방법 측면에서 방법적 지식과 사고 능력으로서의 성격을 갖는다. 즉 새로운 지식의 생산에 필요한 범교과적 학습 능력으로서의 위상을 갖는다. 문제는 이러한 성격이 교과 교육 과정은 물론 학생 일상생활과의 부단한 연계를 통해서 구현된다는 점이다. 즉 학교도서관 교육의 성공을 위해서는 학교 공동체 내에 학교 도서관 중심의 교육 공동체 구성이 필요하다. 학교도서관 정보화와 순회 사서를 포함한 비정규직 자원 봉사자 확산, 다양한 형태의 업무 대행 서비스 그리고 담당교사의 도서관 운영 연수 확대 속에서 자료 조직과 운영의 일부분은 영역 보편성을 띤지 오래되었다. 따라서 학교도서관 중심의 교육 공동체 구성은 도서관 활용수업으로 대표되는 교과의 자원기반학습과의 연계성에 기반을 두고 발전하는 추세이다. 본고에서는 필자가 개발 책임자로 참여하여 2010년 교육과학기술부와 대구광역시교육청이 공동으로 일선 학교에 보급한 사서교사와 교과교사의 협동수업용 장학 자료집의 주요 내용과 활성화 방안을 살펴보고자 한다.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.53-57
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• 2006

현재, 많은 분야에서 데이터 모델링을 지원하는 GIS관련 프로그램으로 ArcObject 컴포넌트를 제안하고 있다. 특히 수자원분야에서 유역과 하천네트워크의 정확하고 효과적인 표현을 위해 ArcHydro Model이 개발되었으며 다양한 분야에서 활용되고 있다. 본 연구에서는 안성군 고삼면의 안고용수구역을 대상으로 ArcHydro Model을 이용하여 관개 네트워크를 구성하기 위해 유역경계, 하천망, 수리시설물의 위치도, 수혜구역도 등의 기본 공간자료들을 구축하고, 이 자료들을 이용하여 수리시설물에 따른 수혜구역을 가시적으로 확인가능하도록 하기 위해 하천의 위상관계를 정립하고 공간자료간의 연계성을 구성하였다. 또한 수리시설물의 농업용수 수요공급량의 정량적인 정보를 획득하기 위하여 ArcHydro Model에 한국농촌공사에서 개발한 AWDS (Agricultural Water Demand and Supply Estimation System. 농촌용수 수요공급량 시스템)와 연계하고, 시설물정보, 수요량분석, 공급량분석을 할 수 있는 메뉴를 구성하여 그 정보를 획득하였다.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.516-517
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• 2014

태양광과 풍력발전 등 분산전원의 대용량 발전이 기존 계통에 미치는 영향이 커짐에 따라, 계통 전압의 안정적인 유지를 위해 필요한 지원이 계통에 연계되는 분산전원들에게 요구되고 있다. 특히나 Low Voltage Ride Through (LVRT) 시에는 계통에서 탈락되지 않는 것은 물론이고, 계통전압 회복을 돕기위해 무효전력을 주입해야 한다. 이러한 사고 상황에서 계통에서 탈락되지 않고 계속적인 계통지원을 위해서는 빠르고 정확한 위상 추종이 필수적이다. 본 논문은 고조파에 강인하고 응답특성이 우수한 Low Pass Notch (LPN) PLL 기법을 LVRT에 적용하여 이의 우수함을 확인한다.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.188-190
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• 2009

본 연구에서는 독립운전 검출기법의 능동적 기법 중 AFDPF 기법을 IEEE Std 929-2000에 제시된 독립운전 시험 조건하에서 위상동기기법 영점검출방식(Zero Crossing PLL)을 적용하여 독립운전 시 chopping fraction에 따른 PCC(Point of Common Coupling)의 주파수 변동 특성을 PSIM을 통하여 분석하였다

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.396-404
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• 2011

This paper proposes a performance improvement of a grid-connected wind turbine using sliding-mode based direct power control under an unbalanced grid fault. The proposed control method has some advantages for grid connected control. At first, it doesn't need the synchronous phase angle of the grid voltage. It has also fast dynamic characteristics compared with a conventional current controller. In addition, it is suitable for an unbalance compensation control. The effectiveness and robustness of the proposed algorithm are verified by simulations and experiments.

• Journal of KIISE:Information Networking
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• v.35 no.4
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• pp.251-267
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• 2008

In this paper, we present a distributed topology control algorithm for constructing an optimized topology having a minimal search-time in unstructured peer-to-peer network. According to the proposed algorithm, each node selects the best nodes having higher hit-ratio than other nodes as many as the number being exponentially proportional to the hit-ratio of the node itself, and then it connects to them. The ensemble behavior of the proposed algorithm is very similar to the recrystrallizing phenomenon that is observed in nature. There is a partial order relationship among the hit-ratios of most nodes of constructed topology. Therefore once query message visits a node, it has a higher hit-ratio than the node that was visited last by the message. The query message even sent from freeloader can escape to the node having high hit-ratio by one hop forwarding, and it never revisits any freeloader again. Thus the search can be completed within a limited search time. We also propose the Chain-reactive search scheme using the constructed topology. Such a controlled multicasting reduces the query messages by 43 percent compared to that of the naive Gnutella using broadcasting, while it saves the search time by 94 percent. The search success rate of the proposed scheme is 99 percent.

• Convergence Security Journal
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• v.12 no.2
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• pp.87-98
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• 2012

The department has established a variety of studies and training courses and has tried to nurture talented people for security companies. However, the research is marginal, and each university department of security guard education, curriculum falling due after graduating students. Moreover, even if students are occupied an employment exceptional adaptability has occurred. Therefore, each university of private security department will need to collaborate with competitive private security company for reinforce and employment rate in center of experienced field. Then, the security's society will be placed in professional occupation, elevate the phase and will decrease the turnover rate. Qualification system of private security have been indicated in distrust, moreover the system have to be adjusted because not enough effort, control system, cooperation system with training center, one-sided emphasis and private inquiry by adding in private security law.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.225-233
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• 2006

Creating more efficient and effective intermodal transportation service in Northeast range is a critical issue because of more increased trade volume & demand for intermodal service in the world market and geographical barriers associated with goods transportation, especially in Korea, China and Japan. This study examines the possibility of Rail-ferry in Northest area which can provide each countries mutual economical and logistical satisfaction.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.37-44
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• 2004

This paper represents a new approach for the protective relay of power transmission lines using a Artificial Neural Network(ANN). A different fault m transmission lines need to be detected classified and located accurately and cleared as fast as possible. However, The protection range of the distance relay is always designed on the basis of fixed settings, and unfortunately these approach do not have the ability to adapt dynamically to the system operating condition. ANN is suitable for the adaptive relaying and the detection of complex faults. The backpropagation algerian based multi-layer protection is utilized for the teaming process. It allows to make control to various protection functions. As expected, the simulation result demonstrate that this approach is useful and satisfactory.