1,733,597 research outputs found
Jong-Min Kim
No full textDaeyoung Kim, Jong-Min Kim, Shu-Min Liao, Yoon-Sung Jung, Mixture of D-vine copulas for modeling dependence, Computational Statistics & Data Analysis, Volume 63, August 2013, 1-19. http://dx.doi.org/10.1016/j.csda.2013.02.018.https://digitalcommons.morris.umn.edu/cosa2013/1030/thumbnail.jp
Seok-Min Kim
No full text학위논문(박사)--아주대학교 일반대학원 :전자공학과,2020. 2본 논문은 다단 H-bridge 멀티레벨 컨버터와 모듈형 멀티레벨 컨버터의 스위치 고장 허용 제어 기법을 제시한다. 일반적인 멀티레벨 컨버터의 허용 제어는 추가로 설치된 단위 모듈을 이용한다. 본 논문에서 제안하는 허용 제어 기법은 전력반도체소자의 고장이 발생하여도 추가 단위 모듈을 사용하지 않고 3상 선간 전압과 전류의 평형을 효과적으로 유지할 수 있다. 제안하는 허용 제어 기술은 추가적으로 교차 변조 기법을 적용하여 고장 상황 시에 발생되는 모듈 간 전달 전력의 극심한 불균형 문제를 해소한다. 제안하는 허용 제어 기법은 개방성 고장과 단락성 고장 모두를 대응하기 위한 두 가지 방법으로 구성된다.
전력반도체소자의 수명은 온도에 기인하며 스위칭 손실은 온도를 높이는 열원으로 변환된다. 본 논문은 전력반도체소자의 수명을 연장하기 위해 모듈형 멀티레벨 컨버터의 스위칭 손실을 저감하면서도 높은 품질의 전압과 전류를 출력할 수 있는 변조 기법을 제안한다. 제안하는 변조 기법은 스위칭 손실 저감을 위한 불연속 구간을 포함하며 해당 불연속 구간은 서브모듈의 커패시터 전압을 극심하게 변동 시키는 요인이다. 서브모듈 간 전압 균형 제어를 유지하기 위해 제안하는 변조 기법은 불연속 변조와 재구성된 사인파 변조를 교차로 수행한다. 불연속 구간에 의해 스위칭 손실을 효과적으로 저감하면서도 각 서브모듈의 커패시터 전압을 균등하게 유지할 수 있으며 기존의 변조 기법과 유사한 품질의 전압과 전류를 출력할 수 있다.
본 논문에서 제안하는 기법은 다양한 시뮬레이션과 실험 결과를 통해 성능과실현 가능성을 검증한다.제 1 장 서 론 1
1.1 연구의 배경 1
1.2 연구의 목적 7
1.2.1 멀티레벨 컨버터의 고장 허용 제어 7
1.2.2 멀티레벨 컨버터의 스위칭 손실 저감 8
1.3 논문의 구성 9
제 2 장 모듈형 멀티-셀 컨버터 10
2.1 다단 H-bridge 멀티레벨 컨버터 10
2.1.1 다단 H-bridge 멀티레벨 컨버터 회로 구조 10
2.1.2 다단 H-bridge 멀티레벨 컨버터의 전압 변조 12
2.2 모듈형 멀티레벨 컨버터 23
2.2.1 모듈형 멀티레벨 컨버터 회로 구조 23
2.2.2 모듈형 멀티레벨 컨버터의 전압 변조 25
제 3 장 다단 H-bridge 컨버터의 스위치 고장 허용 제어 30
3.1 다단 H-bridge 컨버터의 스위치 고장 분석 30
3.2 중성점 천이 기반 허용 제어 기법 32
3.3 3상 CHMC의 스위치 고장 대응을 위한 변조 기법 37
3.3.1 개방성 및 단락성 스위치 고장 허용 제어 38
3.3.2 개방성 스위치 고장 허용 제어 40
3.3.3 서브모듈 간 전력 균등 분배를 위한 교차 변조 42
3.4 시뮬레이션 결과 분석 45
3.5 실험 결과 분석 50
제 4 장 3상 MMC의 스위치 고장 허용 제어 55
4.1 모듈형 멀티레벨 컨버터의 스위치 고장 55
4.2 3상 MMC의 스위치 고장 대응을 위한 변조 기법 59
4.2.1 Sorting 알고리즘 기반 대체 서브모듈 선택 기법 59
4.2.2 선택적 중성점 천이 기법 61
4.2.3 Sorting 알고리즘과 CB-PWM 기반 대체 서브모듈 선택 기법 63
4.3 시뮬레이션 결과 분석 67
제 5 장 MMC의 손실 저감을 위한 하이브리드 변조 기법 74
5.1 MMC의 전기적 모델 74
5.2 스위칭 손실 저감을 위한 하이브리드 변조 기법 77
5.2.1 하이브리드 변조 기법의 원리 77
5.2.2 커패시터 전압 균등 분배를 위한 모듈 간 교차 변조 80
5.3 시뮬레이션 결과 분석 85
5.3.1 하이브리드 변조 기법의 출력 특성 85
5.3.2 스위칭 손실 분석 88
5.4 실험 결과 분석 90
제 6 장 결론 및 요약 95
참고문헌 98DoctoralThis thesis presents switch fault-tolerant strategies for cascaded H-bridge multilevel converter (CHMC) and modular multilevel converter (MMC). The proposed tolerant methods are categorized in two different methods to handle open- and short-circuit faults separately. Most of fault-tolerant methods uses the reserved submodules installed in a multilevel converter. The proposed tolerant method in this thesis can maintain the balanced three-phase line-to-line voltages and currents without reserved submodules under faulty switch condition. Additionally, the rotation scheme is introduced to mitigate unbalanced power distribution among submodules.
The life-time of a power semiconductor relies on its temperature and switching loss is converted as a source of the temperature. This thesis proposes a modulation method for MMCs to reduce the switching loss while the MMC produces high quality output voltage and current. The proposed modulation scheme includes discontinuous modulation period to reduce the switching loss, however, the period causes severe deviation of submodule capacitor voltage. In order to balance the submodule capacitor voltage, the proposed method conducts rotation method using clamping operation and reconfigured sinusoidal modulation both. By applying the clamping operation, the MMC can reduce the switching loss effectively and maintain balanced capacitor voltages.
In this thesis, the effectiveness of the proposed control methods is verified by the simulation and experimental results
Sun-Min,Kim
No full text학위논문(석사)아주대학교 일반대학원 :전자공학과,2012. 2제 1 장 서론 1
제 2 장 분산전원 시스템 3
2.1 분산전원 시스템의 필요성 3
2.2 분산전원 시스템의 계통연계 기준 3
2.3 계통 전압의 왜곡현상 5
제 3 장 제안하는 PLL 시스템 7
3.1 전체시스템 구성 7
3.2 PLL 시스템의 선형화 모델 8
3.3 저차 고조파 영향 12
3.4 전차원 상태관측기 설계 14
제 4 장 시뮬레이션 16
제 5 장 결론 22
참고문헌 23MasterIn a grid connected power conversion system, the phase angle information of a grid voltage is very essential for supplying power to the grid since it is used for active and reactive power control. A Phase Locked Loop (PLL) system is used and should be robust because often the actual grid voltages are usually distorted by unexpected harmonics. However, conventional PLL systems have steady state errors when distorted voltages are used as a PLL input. Furthermore, using this distorted phase angle in the power control could reduce the output power quality. In this paper, the grid voltages are separated into fundamental and harmonic components and a virtual phase voltage is generated from the fundamental component using a Full Order Observer (FOO). Two virtual voltages are used as an input for the PLL system so the phase angle errors can be reduced and the output power quality can be improved. The dynamic characteristics of the PLL system are designed using the modeling method to improve the dynamic response and stability of the whole system. The performance of the proposed method has been verified by a comparative analysis to the conventional PLL system. It is concluded the proposed method works well
Korean Violinist Min Kim: His Devotion to and Achievements in Chamber Music
Full text linkWestern music in Korea has barely a one hundred-year history, and it developed particularly rapidly after the Korean War (1950-1953) as the economy began to grow. In the present day, many Koreans have been trained as professional musicians. Despite the individual successes of Korean musicians, there have been few Korean ensembles that have gained international renown.;The purpose of this study is to provide a complete overview of the Korean violinist Min Kim, including his biography, teaching, and especially his great influence on and achievements in chamber music in Korea. The main sources of material for this study are interviews with Min Kim and several of his pupils, conducted by the author, and articles in journals which were written based on interviews with Kim. Previously published interviews with Kim have been translated from Korean to English by the author. It also presents a general overview of the history of the violin in Korea. The study consists of five chapters: (1) Introduction, (2) A musical history of the violin in Korea, (3) Korean violinist Min Kim, (4) Kim as a director and leader of the Korean Chamber Orchestra, and (5) Conclusion.;Min Kim (1942-) is one of the most influential violinists in Korea, and he is considered to be the leader of the fourth generation of great violinists in the country. After studying at Seoul National University, he went to Germany to study as a Deutscher Akademischer Austauschdienst (DAAD, German Academic Exchange Service) student in 1969, where he had various musical experiences, especially as a chamber and orchestral musician. In 1979, Kim returned from Germany, and began to share his musical experiences with the next generation of Korean musicians. He especially contributed many achievements in the development of chamber music in Korea. Kim devoted most of his musical life to the Korean Chamber Orchestra, which was founded in 1965 by cellist Bong Cho Jeon (1919-2002), and disbanded in 1975. In 1979, Kim reorganized the ensemble, and it gave a second debut concert in 1980. Since then, the ensemble has given approximately five hundred concerts in Korea and other countries around the world.;The primary finding of this study is that Min Kim had a great influence on the development of Western music in Korea, especially on violin and chamber music. There is no doubt that Kim was one of the most important pioneers of chamber music in Korea, and that he and the Korean Chamber Orchestra enabled chamber music to become firmly rooted in the country. Subsequent generations should continue studying and performing chamber music in order to further develop the country\u27s musical tradition
Bilbo readme
No full textBILBO : Automatic reference labeling (C) Copyright 2013 by Young-Min Kim and Jade Tavernier. written by Young-Min Kim, modified by Jade Tavernier. BILBO is an open source software for automatic annotation of bibliographic reference. It provides the segmentation and tagging of input string. It is principally based on Conditional Random Fields (CRFs), machine learning technique to segment and label sequence data. As external softwares, Wapiti is used for CRF learning and inference and SVMlight ..
Pan-cancer analysis of somatic mutations and transcriptomes reveals common functional gene clusters shared by multiple cancer types
No full textAbstractTo discover functional gene clusters across cancers, we performed a systematic pan-cancer analysis of 33 cancer types. We identified genes that were associated with somatic mutations and were the cores of a co-expression network. We found that multiple cancer types have relatively exclusive hub genes individually; however, the hub genes cooperate with each other based on their functional relationship. When we built a protein-protein interaction network of hub genes and found nine functional gene clusters across cancer types, the gene clusters divided not only the region of the network map, but also the function of the network by their distinct roles related to the development and progression of cancer. This functional relationship between the clusters and cancers was underpinned by the high expression of module genes and enrichment of programmed cell death, and known candidate cancer genes. In addition to protein-coding hub genes, non-coding hub genes had a possible relationship with cancer. Overall, our approach of investigating cancer genes enabled finding pan-cancer hub genes and common functional gene clusters shared by multiple cancer types based on the expression status of the primary tumour and the functional relationship of genes in the biological network.</jats:p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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