A5101718457- Superconducting Materials and Applications
- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Color Science and Applications
- Advancements in Photolithography Techniques
- Atomic and Molecular Physics
- Diamond and Carbon-based Materials Research
- HVDC Systems and Fault Protection
- Plasma Diagnostics and Applications
- Photocathodes and Microchannel Plates
- Korean Urban and Social Studies
- Laser Design and Applications
- Color perception and design
- Image Enhancement Techniques
- Advanced X-ray Imaging Techniques
- Advanced Sensor and Control Systems
- Electromagnetic Launch and Propulsion Technology
- Laser-Plasma Interactions and Diagnostics
- Air Quality Monitoring and Forecasting
- Atmospheric chemistry and aerosols
- Air Quality and Health Impacts
- Urban and spatial planning
- Visual perception and processing mechanisms
- Particle Accelerators and Free-Electron Lasers
- Solid State Laser Technologies
National Institute of Environmental Research
2018-2022
Korea Institute of Fusion Energy
2019-2020
ITER
2010-2019
Seoul National University
2016
Seoul National University Hospital
2016
New Generation University College
2016
Tokyo Institute of Technology
2003-2015
Pohang Iron and Steel (South Korea)
2000-2007
Korea University
2001-2007
Pemaquid Oyster Company (United States)
2007
The ITER Coil Power Supply and Distribution System (CPSDS) will be installed to receive power from the French 400 kV transmission grid provide controlled DC superconducting tokamak magnets for plasma operation. (CPSS) consists of AC/DC converter units connected in series with Switching Network Units (SNU) Fast Discharge (FDU) initiation, current, shape position control, error field correction, as well superconductive magnet quench protection. CPSS is nearly 2 GVA. Thyristor based technology...
High DC current interruption system and large energy dissipation are required for the protection of ITER superconductive coils. The superconducting magnets will store up to 56 GJ magnetic per operation cycle. In case coil quench other fault conditions stored in coils must be discharged quickly safely within a discharge time constant from 7.5 14 second. It can achieved by Fast Discharge Unit (FDU), which consists circuit breaker dump resistors. paper present its peculiarities challenging...
The objective of this study was to determine comprehensive chemical components in PM2.5 from March 2011 till February 2012 Seoul, South Korea, and their contributions light extinction. Major the aerosol were: ammonium sulfate, 30.3%; nitrate, 25.2%; organic matter, 21.3%; crustal mass, 16.9%; element carbon, 6.1%; trace metals, 0.2%. mass concentrations extinction were mostly correlated diurnal monthly variations, which indicates that is key variable Seoul. However, size composition (of...
A miniature hybrid plasma focus device, operated in xenon gas medium and driven by a 10kA fast current pulse, has been used to generate extreme ultraviolet radiation the range of 6–15nm. At present characteristics from were mainly assessed qualitatively using standard tools such as visible light framing camera, (EUV) pinhole EUV photodiode. Strong pinching is indicative both imagings. The maximum size emitting zone estimated be order 0.21×1.55mm value within accepted benchmarked industries....
This paper presents two-stage high-power mechanical-thyristor switches developed as 40-kA direct current (dc) circuit breakers for the superconducting coil energy dump system of Korea Tokamak advanced research (KSTAR). An switching used in quench protection should allow multishot mode operation without maintenance and long lifetime with arcless dc commutation. The is designed to combine advantages both mechanical solid-state power switches. stage conduct normal thyristor provide fast...
Highly efficient and compact pulsed power supply system for a capillary discharge soft x-ray laser (SXRL) has been developed. The consists of 2.2 μF two-stage LC inversion generator, 2:54 step-up transformer, 3 nF water capacitor, section with few tens centimeter length capillary. Adoption the transformer in combination generator enables us to use only one gap switch circuit charging capacitor up about 0.5 MV. Furthermore, ratio voltage initial is 40 energy transfer efficiency 50%. It also...
In fusion experiments, interruption units for high DC currents are widely used generating the loop voltage required at plasma breakdown and current start-up. Likewise, similar systems employed protection of superconductive coils in case quench (i.e. a loss superconductivity). such event, large resistor banks inserted circuits by means circuit breakers, so as to dissipate energy stored coils.The ITER experiment, largest facility ever conceived, is currently under construction south France...
The emission spectra of hydrogen-like nitrogen Balmer at the wavelength 13.4 nm in capillary Z-pinch discharge plasma are experimentally examined. Ionization to fully strip pinch maximum, and subsequent rapid expansion cooling required establish population inversion between principal quantum number n = 2 3. ionization recombination processes with estimated parameters evaluated by utilizing a time integrated spectrum pinhole image containing radial spatial information. A cylindrical is...
ITER plasma requires the use of an internal vertical stabilization (VS) coil set as part system for active control position. The required peak current and voltage VS power supply are order 60 kA 2.4 kV. Also, it needs short response time, less than 1 ms highly transient demand. This paper describes a conceptual design study in-vessel to judge feasibility estimate its cost. Finally, result will be used input data Tokamak building other interface systems.
The upgradation of the Korea superconducting tokamak advanced research (KSTAR) toroidal field (TF) coil quench protection (QP) system has been performed since failure 40-kA dc interruption switch it in 2016. complicated design and logic led to accident QP during malfunction interlock power-line carrier (PLC). To improve reliability TF system, KSTAR decided apply pyrobreaker (PB) from Efremov Institute as a backup for slow discharge (SD) switches. In addition, upgraded segregates circuit SD...
The development and use of a single-fluid two-temperature approximated 2-D Magneto-Hydrodynamics code is reported. Z-pinch dynamics the evolution Magneto-Rayleigh-Taylor (MRT) instabilities in gas jet type Extreme Ultraviolet (EUV) source are investigated with this code. implosion stagnation processes influence initial perturbations (single mode, multi- random seeds) on MRT instability discussed detail. In case single mode seeds, simulation shows that growth rates for mm-scale wavelengths up...
In this paper we present a capacitor charging power supply (CCPS) using series-resonant three-level inverter topology to improve voltage regulation and use semiconductor switches having low blocking capability such as MOSFETs. This can be operated with two modes, full mode (FPM) half (HPM). FPM supplies the high frequency step up transformer DC-link voltage(V/sub DC/) in HPM DC//2). switching method will adopted when CCPS output reaches preset target value operates refresh mode-charge is...
Next-generation lithography will require an extreme-ultraviolet (EUV) light source that ensures high radiation intensities at a wavelength of around 13.5 nm. The characteristics pinch dynamics and emission in this spectral range were studied experimentally for xenon capillary Z-pinch plasma driven by different d I / t discharge current pulses. the examined employing high-speed camera, from was inspected using EUV photodiode, mini calorimeter spectrometers. Our results confirm high- has...
A pinhole camera has been employed to study the performance of a xenon capillary Z-pinch extreme ultraviolet (EUV) lithography light source driven by different dI/dt discharge current pulses. The EUV in terms dimension, intensity, collection efficiency and stability was specifically investigated varying experimental conditions such as supplying gas pressure current. Specific features, ring shape (annular profile) images symmetrical stable emission high current, have observed or confirmed...
Extreme ultraviolet (EUV) emission from a gas jet z-pinch source has been examined by employing photodiode and pinhole camera. Visible images of the pinched plasma have also recorded. A current pulse 10kA is used to heat jet, which emits radiation around 13.5nm. Experimental parameters such as electrode separation flow rate are varied optimize EUV emission. The maximum energy obtained for 12mm 20Torr xenon pressure it estimated 10.95mJ∕sr per 2% bandwidth pulse. presence curtain improves 30%.