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High Performance Current Controller for Sparse Matrix Converter Based on Model Predictive Control
Eunsil Lee,Kyo-Beum Lee,Young Il Lee,Joong-Ho Song 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.5
A novel predictive current control strategy for a sparse matrix converter is presented. The sparse matrix converter is functionally-equivalent to the direct matrix converter but has a reduced number of switches. The predictive current control uses a model of the system to predict the future value of the load current and generates the reference voltage vector that minimizes a given cost function so that space vector modulation is achieved. The results show that the proposed controller for sparse matrix converters controls the load current very effectively and performs very well through simulation and experimental results.
High Performance Current Controller for Sparse Matrix Converter Based on Model Predictive Control
Lee, Eunsil,Lee, Kyo-Beum,Lee, Young Il,Song, Joong-Ho The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.5
A novel predictive current control strategy for a sparse matrix converter is presented. The sparse matrix converter is functionally-equivalent to the direct matrix converter but has a reduced number of switches. The predictive current control uses a model of the system to predict the future value of the load current and generates the reference voltage vector that minimizes a given cost function so that space vector modulation is achieved. The results show that the proposed controller for sparse matrix converters controls the load current very effectively and performs very well through simulation and experimental results.
Lee Eunsil,Pee Jae-Hwan,Lee Sung-Min,Kim Jong-Young,Shim Wooyoung 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.8
An enhanced high- temperature electrical resistivity of AlN at high voltage was obtained by using MgO doping to modulate the Schottky barrier. Doped MgO was precipitated in an ~100-nm-thick layer near grain boundaries, which reduced not only anionic carriers, but also the carrier mobility, due to the formation of defects (Mg´Al, O·N). According to an impedance analysis, the activation energy and the resistivity due to grain boundaries were increased by MgO doping, suggesting an elevated Schottky barrier. As a result, a remarkable high-voltage electrical resistivity, which is greater than 1010 Ω·cm at 550 °C/100 V, can be achieved, which is valuable for electrostatic chucking devices.
Eunsil Lee,Kyo-Beum Lee 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.1
Reverse matrix converters, which can step up voltages, are suitable for applications with source voltages that are lower than load voltages, such as generator systems. Reverse matrix converter topologies are advantageous because they do not require additional components to conventional matrix converters. In this paper, a detection method and a post-fault modulation strategy to operate a converter as close as possible to its desired normal operation under the open-switch fault condition in the rectifier stage are proposed. An open-switch fault in the rectifier stage of a reverse matrix converter causes current distortions and voltage ripples in the system. Therefore, fault-tolerant control for open-switch faults is required to improve the reliability of a system. The proposed strategy determines the appropriate switching stages from among the remaining healthy switches of the converter. This is done based on reference currents or voltages. The performance of the proposed strategy is experimentally verified.
Eunsil Lee 한국영어어문교육학회 2008 영어어문교육 Vol.14 No.2
This paper examines study abroad students" emotional issues when they first arrived in the target culture. The participants in this study had problems in communicating with the target language and also confronted personal problems such as loneliness, discrimination, homesickness. as well as feeling powerless. This made them easily emotional and venerable, and this influenced their learning. too. The language learners emotional problems could be considered as a timely matter that would go away as time passes. However, it was important to look at the problems closely and think about how we could help the learners deal with their emotional breakdowns and concentrate more on learning. This qualitative research aims to explore affective part of language learning process in language learners" particular social and cultural environment. Data was gathered by conducting in-depth interviews and shadowing observations in various settings. Field notes were filled, and the conversations were taped and transcribed. The research suggests that emotional problems students face during study abroad can be an important cue that shows how they manage their language learning. Therefore, the findings of this study will identify emotional elements bothering the language learners and provide the ways the learners got over them and become more confident.
Lee, Eunsil,Lee, Kyo-Beum The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.1
Reverse matrix converters, which can step up voltages, are suitable for applications with source voltages that are lower than load voltages, such as generator systems. Reverse matrix converter topologies are advantageous because they do not require additional components to conventional matrix converters. In this paper, a detection method and a post-fault modulation strategy to operate a converter as close as possible to its desired normal operation under the open-switch fault condition in the rectifier stage are proposed. An open-switch fault in the rectifier stage of a reverse matrix converter causes current distortions and voltage ripples in the system. Therefore, fault-tolerant control for open-switch faults is required to improve the reliability of a system. The proposed strategy determines the appropriate switching stages from among the remaining healthy switches of the converter. This is done based on reference currents or voltages. The performance of the proposed strategy is experimentally verified.
Lee, Hye Shin,Choi, Jinhyeok,Son, Taekwon,Lee, Eun Ji,Kim, Jeong-Gyun,Ryu, Soo Hyung,Lee, Danbi,Jang, Myoung Kuk,Yu, Eunsil,Chung, Young-Hwa,Gelman, Irwin H.,Kim, Kyu-Won D.A. Spandidos 2018 Oncology letters Vol.16 No.5
<P>AKAP12 belongs to A-kinase anchoring protein (AKAP) family of scaffold proteins and is known as a tumor suppressor in several human cancer types. Its role as a tumor suppressor in hepatocellular carcinoma (HCC) was proposed due to its downregulation and epigenetic modification in human HCC; however, the effect of its deficiency on liver injuries, such as liver fibrosis and cancer has been poorly studied. By analyzing tumor and non-tumor tissues of 15 patients with HCC, it was confirmed that AKAP12 expression was downregulated in human HCC as compared with adjacent non-tumor tissues. Immunohistochemical staining of mouse liver tissue for AKAP12 revealed that its sinusoidal expression was diminished in capillarized endothelium after 8 weeks of thioacetamide (TAA) administration. AKAP12 deficiency resulted in the promotion of ductular response of biliary epithelial cells, whereas overall fibrosis and myofibroblast activation were comparable between genotypes after short-term TAA treatment. The mRNA expressions of some fibrosis-related genes such as those encoding epithelial cell adhesion molecule, collagen type 1 α1 and elastin were upregulated in liver tissues of AKAP12-knockout mice. Long-term administration of TAA for 26 weeks led to the development of liver tumors; the incidence of tumor development was higher in AKAP12-deficient mice than in wild-type littermates. Together, these results suggest that AKAP12 functions as a tumor suppressor in liver cancer and is associated with the regulation of hepatic non-parenchymal cells.</P>
Lee, Eunsil,Kim, Jin Il,Choi, Soon-Mok,Lim, Young Soo,Seo, Won-Seon,Kim, Jong-Young,Lee, Kyu Hyoung Hindawi Limited 2015 Journal of nanomaterials Vol.2015 No.-
<P>We suggest a simple and scalable synthesis to prepare Cu-<SUB>Bi2</SUB><SUB>Te2.7</SUB><SUB>Se0.3</SUB>(Cu-BTS) nanocomposites. By precipitating Cu nanoparticle (NP) in colloidal suspension of as-exfoliated BTS, homogeneous mixtures of Cu NP and BTS nanosheet were readily achieved, and then the sintered nanocomposites were fabricated by spark plasma sintering technique using the mixed powder as a raw material. The precipitated Cu NPs in the BTS matrix effectively generated nanograin (BTS) and heterointerface (Cu/BTS) structures. The maximumZTof 0.90 at 400 K, which is 15% higher compared to that of pristine BTS, was obtained in 3 vol% Cu-BTS nanocomposite. The enhancement ofZTresulted from improved power factor by carrier filtering effect due to the Cu nanoprecipitates in the BTS matrix.</P>
Eunsil Lee,Kyo-Beum Lee 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.6
This paper presents the development of a system with a reverse matrix converter (RMC) for permanent magnet synchronous motor (PMSM) drive and its effective control method. The voltage transfer ratio of the general matrix converter is restricted to a maximum value of 0.866, which is not suitable for applications whose source voltages are lower than the load voltages. The proposed RMC topology can step up the voltage without any additional components in the conventional circuit. Its control method is different from traditional matrix converter’s one, thus this paper proposes control schemes of RMC by means of controlling both the generator and motor side currents with properly designed control loop. The converter can have sinusoidal input/output current waveforms in steady state condition as well as a boosted voltage. In this paper, a hardware system with an RMC for a PMSM drive system is described. The performance of the system was investigated through experiments