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Lee W, Leem J, Yun GS, Park HK, Ko SH, Wang WX, Budny RV, Luhmann NC, Kim KW. Ion gyroscale fluctuation measurement with microwave imaging reflectometer on KSTAR. Rev Sci Instrum 2016; 87:11E134. [PMID: 27910475 DOI: 10.1063/1.4963152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Ion gyroscale turbulent fluctuations with the poloidal wavenumber kθ ∼ 3 cm-1 have been measured in the core region of the neutral beam (NB) injected low confinement (L-mode) plasmas on Korea superconducting tokamak advanced research. The turbulence poloidal wavenumbers are deduced from the frequencies and poloidal rotation velocities in the laboratory frame, measured by the multichannel microwave imaging reflectometer. Linear and nonlinear gyrokinetic simulations also predict the unstable modes with the normalized wavenumber kθρs ∼ 0.4, consistent with the measurement. Comparison of the measured frequencies with the intrinsic mode frequencies from the linear simulations indicates that the measured ones are primarily due to the E × B flow velocity in the NB-injected fast rotating plasmas.
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Affiliation(s)
- W Lee
- National Fusion Research Institute, Daejeon 34133, South Korea
| | - J Leem
- Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - G S Yun
- Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - H K Park
- National Fusion Research Institute, Daejeon 34133, South Korea
| | - S H Ko
- National Fusion Research Institute, Daejeon 34133, South Korea
| | - W X Wang
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - R V Budny
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - N C Luhmann
- University of California at Davis, Davis, California 95616, USA
| | - K W Kim
- Kyungpook National University, Daegu 41566, South Korea
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Lee W, Park HK, Lee DJ, Nam YU, Leem J, Kim TK. Design of a collective scattering system for small scale turbulence study in Korea Superconducting Tokamak Advanced Research. Rev Sci Instrum 2016; 87:043501. [PMID: 27131668 DOI: 10.1063/1.4944834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The design characteristics of a multi-channel collective (or coherent) scattering system for small scale turbulence study in Korea Superconducting Tokamak Advanced Research (KSTAR), which is planned to be installed in 2017, are given in this paper. A few critical issues are discussed in depth such as the Faraday and Cotton-Mouton effects on the beam polarization, radial spatial resolution, probe beam frequency, polarization, and power. A proper and feasible optics with the 300 GHz probe beam, which was designed based on these issues, provides a simultaneous measurement of electron density fluctuations at four discrete poloidal wavenumbers up to 24 cm(-1). The upper limit corresponds to the normalized wavenumber kθρe of ∼0.15 in nominal KSTAR plasmas. To detect the scattered beam power and extract phase information, a quadrature detection system consisting of four-channel antenna/detector array and electronics will be employed.
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Affiliation(s)
- W Lee
- Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
| | - H K Park
- Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
| | - D J Lee
- Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
| | - Y U Nam
- National Fusion Research Institute, Daejeon 34133, South Korea
| | - J Leem
- Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - T K Kim
- Kyunpook National University, Daegu 41566, South Korea
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Yun GS, Lee W, Choi MJ, Lee J, Kim M, Leem J, Nam Y, Choe GH, Park HK, Park H, Woo DS, Kim KW, Domier CW, Luhmann NC, Ito N, Mase A, Lee SG. Quasi 3D ECE imaging system for study of MHD instabilities in KSTAR. Rev Sci Instrum 2014; 85:11D820. [PMID: 25430233 DOI: 10.1063/1.4890401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A second electron cyclotron emission imaging (ECEI) system has been installed on the KSTAR tokamak, toroidally separated by 1/16th of the torus from the first ECEI system. For the first time, the dynamical evolutions of MHD instabilities from the plasma core to the edge have been visualized in quasi-3D for a wide range of the KSTAR operation (B0 = 1.7∼3.5 T). This flexible diagnostic capability has been realized by substantial improvements in large-aperture quasi-optical microwave components including the development of broad-band polarization rotators for imaging of the fundamental ordinary ECE as well as the usual 2nd harmonic extraordinary ECE.
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Affiliation(s)
- G S Yun
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - W Lee
- Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea
| | - M J Choi
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - J Lee
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - M Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - J Leem
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Y Nam
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - G H Choe
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - H K Park
- Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea
| | - H Park
- School of Electrical Engineering, Kyungpook National University, Daegu 702-701, Korea
| | - D S Woo
- School of Electrical Engineering, Kyungpook National University, Daegu 702-701, Korea
| | - K W Kim
- School of Electrical Engineering, Kyungpook National University, Daegu 702-701, Korea
| | - C W Domier
- Department of Electrical and Computer Engineering, University of California, Davis, California 95616, USA
| | - N C Luhmann
- Department of Electrical and Computer Engineering, University of California, Davis, California 95616, USA
| | - N Ito
- KASTEC, Kyushu University, Kasuga-shi, Fukuoka 812-8581, Japan
| | - A Mase
- Ube National College of Technology, Ube-shi, Yamaguchi 755-8555, Japan
| | - S G Lee
- National Fusion Research Institute, Daejeon 305-333, Korea
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Lee M, Jung C, Kang Y, Hwang J, Jang J, Leem J, Park JY, Kim HK, Lee W. Serum bilirubin as a predictor of incident metabolic syndrome: A 4-year retrospective longitudinal study of 6205 initially healthy Korean men. Diabetes & Metabolism 2014; 40:305-9. [DOI: 10.1016/j.diabet.2014.04.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 04/22/2014] [Accepted: 04/25/2014] [Indexed: 10/25/2022]
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Jung CH, Lee WJ, Hwang JY, Yu JH, Shin MS, Lee MJ, Jang JE, Leem J, Park JY, Kim HK. Assessment of the fatty liver index as an indicator of hepatic steatosis for predicting incident diabetes independently of insulin resistance in a Korean population. Diabet Med 2013; 30:428-35. [PMID: 23278318 DOI: 10.1111/dme.12104] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 10/24/2012] [Accepted: 12/18/2012] [Indexed: 02/06/2023]
Abstract
AIMS Fatty liver disease, especially non-alcoholic fatty liver disease, is considered to be the hepatic manifestation of the metabolic syndrome, both closely associated with insulin resistance. Furthermore, fatty liver disease assessed by ultrasonography is known to be a predictor of the development of Type 2 diabetes mellitus. However, it remains unclear whether fatty liver disease plays a role in the pathogenesis of Type 2 diabetes independently of insulin resistance. In this study, we investigated whether fatty liver disease assessed by the fatty liver index can predict the development of Type 2 diabetes independently of systemic insulin resistance. METHODS We examined the clinical and laboratory data of 7860 subjects without diabetes who underwent general routine health evaluations at the Asan Medical Center in 2007 and had returned for follow-up examinations in 2011. Fatty liver index was calculated using an equation that considers serum triglyceride levels, γ-glutamyltransferase, waist circumference and BMI. RESULTS During a 4-year period, 457 incident diabetes cases (5.8%) were identified. The odds ratios for the development of Type 2 diabetes were significantly higher in the group with a fatty liver index ≥ 60 (fatty liver index-positive) than in the group with a fatty liver index < 20 (fatty liver index-negative) after adjusting for various confounding variables including homeostasis model assessment of insulin resistance. Odds ratios were significant regardless of the insulin resistance status at baseline. CONCLUSIONS Our results suggest that fatty liver index as a simple surrogate indicator of hepatic steatosis is valuable in identifying subjects at high risk for Type 2 diabetes. In addition, fatty liver disease itself contributes to the development of Type 2 diabetes independently of systemic insulin resistance.
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Affiliation(s)
- C H Jung
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
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Kim H, Leem J, Park S, Lee Y, Kim D. Association Between Rhinitis and Exposure to Formaldehyde Among Technicians in a Pathology Department. Epidemiology 2007. [DOI: 10.1097/01.ede.0000276688.23875.1c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Kwon H, Ha M, Jee Y, Hong Y, Leem J, Sakong> J, Bae J, Hong S, Roh Y. The CHEER (Children’s Health and Environmental Research) Study: A Longitudinal Cohort Study on Children’s Environmental Health. Epidemiology 2006. [DOI: 10.1097/00001648-200611001-01080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
In the present study mechanism of inhibitory effects of capsaicin on the contractility of rabbit coronary artery were studied by measurement of isometric tension and intracellular Ca2+ concentration. Capsaicin (1 microM to 30 microM) relaxed the coronary artery pre-contracted with prostaglandin (PG) F2alpha (1 microM) in a concentration-dependent manner. The PGF2alpha-induced increase in intracellular Ca2+ concentration was also inhibited. The effects of capsaicin were readily reversed by washing capsaicin from the bath. Capsaicin-induced relaxation was not attenuated by pretreatment with capsazepine (1 microM), a blocker of vanilloid receptor or ruthenium red (1 microM), a blocker of non-selective cation channel. Previous exposure to a high concentration of capsaicin (100 microM) or repeated application of capsaicin did not eliminate the relaxation response to subsequent application of capsaicin. Increasing the external K+ concentration to 80 mM significantly attenuated the capsaicin-induced relaxation with simultaneous change in intracellular Ca2+ concentration. Pretreatment with iberiotoxin (100 nM), a blocker of Ca2+-activated K+ channel, only partially inhibited the capsaicin-induced relaxation. However, application of 4-aminopyridine (4-AP, 1 mM), a blocker of delayed rectifier K+ current significantly inhibited the capsaicin-induced relaxation with concomitant attenuation of the effect on intracellular Ca2+ concentration. These results indicate that capsaicin may have a direct relaxing effect on the smooth muscle contractility, and relaxation may be due to activation of the 4-AP-sensitive, delayed rectifier K+ channels in the rabbit coronary artery.
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Affiliation(s)
- D Yeon
- Department of Physiology, Yonsei University College of Medicine, Seoul, Korea
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