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다회로 LVDC 전력망 안정화를 위한 운영 알고리즘 실증
이유경 ( Yu-kyeong Lee ),박병우 ( Byung-woo Park ),김춘성 ( Chun-sung Kim ),박성준 ( Sung-jun Park ) 한국산업융합학회 2023 한국산업융합학회 논문집 Vol.26 No.6
In recent years, as the demand for distributed power has increased, the need for microgrids connected to grid power and renewable power generation sources has emerged. In the case of DC microgrids, reactive power does not occur, and power conversion losses are reduced compared to AC when connecting to the load and power grid[2] . With the revitalization of the DC distribution network industry, various studies and demonstrations of DC microgrids have been carried out. In the case of the recent unit distribution, its stability and effectiveness have been verified through empirical and research analysis. However, there is a lack of empirical tests to prevent chain accidents for the protection of the power grid circuits and the misoperation of the distributed power system caused by individual accidents when connecting various distributed power sources and power grids. In this paper, the operation plan of a stable multi-circuit DC distribution connection for the demonstration site was verified through the protection cooperation and operation algorithm for the stable linkage management of the DC distribution network composed of such a multi-circuit.
1997 외환위기 지식그래프: 디지털 아카이브의 관계 중심적 접근
이유경(Yu-kyeong Lee),김학래(Haklae Kim) 한국기록관리학회 2020 한국기록관리학회지 Vol.20 No.4
정보기술의 발전에 따라 아카이브의 디지털화가 가속화되고 있다. 그런데 전통적인 방식의 디지털 아카이브는 기록을 효과적으로 검색하고 연계하고 이해하는 데 한계가 있다. 본 논문은 디지털 아카이브의 활용성을 극대화하기 위한 방안으로 관계 중심의 지식그래프 방식을 제안한다. 디지털 아카이브의 사례인 ‘1997 외환위기 아카이브’의 특징을 검토하고, 아카이브에 포함된 모든 개체와 개체 사이의 관계는 RiC-O(Records in Contexts-Ontology) 기반의 지식그래프로 구축한다. 본 연구의 결과인 외환위기 지식그래프는 1997 외환위기 아카이브의 모든 개체를 기계가 처리할 수 있는 형식으로 구축한다. 디지털 아카이브와 비교해 지식그래프 접근은 개체의 정보, 개체 사이의 관계를 정확히 탐색할 수 있고, 이를 통해 의미검색, 지능형 서비스에 활용될 수 있다. Along with the development of information technology, the digitalization of archives has also been accelerating. However, digital archives have limitations in effectively searching, interlinking, and understanding records. In response to these issues, this study proposes a knowledge graph that represents comprehensive relationships among heterogeneous entities in digital archives. In this case, the knowledge graph organizes resources in the archives on the Korean financial crisis of 1997 by transforming them into named entities that can be discovered by machines. In particular, the study investigates and creates an overview of the characteristics of the archives on the Korean financial crisis as a digital archive. All resources on the archives are described as entities that have relationships with other entities using semantic vocabularies, such as Records in Contexts-Ontology (RiC-O). Moreover, the knowledge graph of the Korean Financial Crisis of 1997 is represented by resource description framework (RDF) vocabularies, a machine-readable format. Compared to conventional digital archives, the knowledge graph enables users to retrieve a specific entity with its semantic information and discover its relationships with other entities. As a result, the knowledge graph can be used for semantic search and various intelligent services.
이유경(Yu-Kyeong Lee),정인성(In-Sung Jeong),최효상(Hyo-Sang Choi) 대한전기학회 2015 전기학회논문지 Vol.64 No.4
In this paper, the shield plate was applied to the wireless power transfer (WPT) system. Then we compared transmission efficiency of WPT system between transmitter and receiver coils. The superconductor coil was applied to transmitter and receiver coils in order to increase the transmission efficiency of WPT. The superconductor coil was more effective to power transmission as its current density was higher than normal conductor coil. Efficiency of WPT between transmitter and receiver coils was changed by a quality of shielding. We used the shielding materials such as glass, iron, steels, aluminum etc. The efficiency of WPT system was depended on the shielding materials of transmitter and receiver coils. As a result, magnetic material such as aluminum, iron reduced the magnetic flux density and the efficiency of WPT. remarkably, but in non-magnetic material such as glass and plastic, the efficiency of WPT was unaffected.