A5066190742- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Radio Frequency Integrated Circuit Design
- Superconducting Materials and Applications
- Gyrotron and Vacuum Electronics Research
- Microwave Engineering and Waveguides
- Ionosphere and magnetosphere dynamics
- Quantum optics and atomic interactions
- GaN-based semiconductor devices and materials
- Advanced Power Amplifier Design
- Plasma Diagnostics and Applications
- Atomic and Subatomic Physics Research
- Full-Duplex Wireless Communications
- Semiconductor Quantum Structures and Devices
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Energy Harvesting in Wireless Networks
- Photonic and Optical Devices
- Semiconductor Lasers and Optical Devices
- Antenna Design and Analysis
- Fluid Dynamics Simulations and Interactions
- Fluid Dynamics and Heat Transfer
- Acoustic Wave Resonator Technologies
- Solar and Space Plasma Dynamics
- Quantum and electron transport phenomena
Jeonbuk National University
2013-2025
Electronics and Telecommunications Research Institute
2024-2025
Korea Institute of Fusion Energy
2014-2024
Jeonbuk Development Institute
2024
Korea Electronics Technology Institute
2021-2022
Hallym University
2014
Hangang Sacred Heart Hospital
2014
Fusion (United States)
2014
Fusion Academy
2014
Pohang University of Science and Technology
1999-2011
Abstract With the rapid increase in demand for next‐generation communication, development of advanced dielectric materials has become imperative. To enhance performance and reliability miniaturized electronic devices, must exhibit high thermal conductivity (λ) while simultaneously fulfilling crucial criteria such as low permittivity ( D k ) loss f ). The synthesis novel polymers (LDPs) is newly reported by integrating fused aromatic mesogens siloxane functions with silane linkers. Fused...
A 20 MW/5 GHz lower hybrid current drive (LHCD) system was initially due to be commissioned and used for the second mission of ITER, i.e. Q = 5 steady state target. Though not part currently planned procurement phase, it is now under consideration an earlier delivery. In this paper, both physics technology conceptual designs are reviewed. Furthermore, appropriate work plan also developed. This design, R&D, installation a MW LHCD on ITER follows Scientific Technical Advisory Committee...
Electron cyclotron resonance heating (ECRH)-assisted plasma breakdown is foreseen with full and half magnetic field in ITER. As reported earlier, the corresponding O1- X2-schemes have been successfully used to assist pre-ionization present-day devices. This contribution reports on common experiments studying effect of toroidal inclination ECR beam, which ⩾20° All devices could demonstrate successful assistance for this case also, although some necessary power was almost a factor 2 higher...
This letter reports on the successful demonstration of second harmonic electron cyclotron heating (ECH)-assisted startup in first plasma experiments recently completed fully superconducting Korea Superconducting Tokamak Advanced Research (KSTAR) device whose major and minor radii are 1.8 m 0.5 m, respectively. For ECH-assisted startup, an 84 GHz EC wave at 0.35 MW was launched before onset toroidal electric field Ohmic system. And it observed that this sufficient to achieve breakdown ECH...
Abstract The fourth KSTAR campaign in 2011 concentrated on active edge-localized mode (ELM) control by various methods such as non-axisymmetric magnetic perturbations, supersonic molecular beam injection (SMBI), vertical jogs of the plasma column and edge electron heating. segmented in-vessel coil (IVCC) system is capable applying n ⩽ 2 perturbed field with different phasing among top, middle bottom coils. Application an = 1 showed a desirable ELM suppression result. Fast achieved...
Abstract The Korean Superconducting Tokamak Advanced Research has been focused on exploring the key physics and engineering issues for future fusion reactors by demonstrating long pulse operation of high beta steady-state discharge. scenarios are being developed with goal operation, significant progress made in ℓ i , hybrid β N 3. In new scenario called fast ion regulated enhanced (FIRE), ions play an essential role confinement enhancement. GK simulations show a reduction thermal energy flux...
The VOF method is adopted for the finite element analysis of transient fluid flow with a free surface. In particular, an adaptation technique generating adaptive grid incorporated to capture higher resolution surface configuration. An created through refinement and mergence elements. this domain elements in region are made finer than those remaining regions more efficient computation. Also, three techniques based on newly developed increase accuracy analysis, namely filling pattern,...
A dual-frequency microwave imaging reflectometry system was commissioned to measure both coherent and turbulent electron density fluctuations in KSTAR plasmas. Imaging of the is achieved with an array 16 vertically aligned detectors two X-mode probe beam frequencies (tunable over 78–92 GHz between plasma discharges). The provides capability fluctuation measurements poloidal wavenumbers (kθ) up ~3 cm−1 at maximum sampling rate 2 MHz. Following extensive laboratory tests, further tested known...
Experiments of electron cyclotron resonance heating (ECH) power scan in KSTAR tokamak clearly demonstrate that both the cut-off density for non-local heat transport (NLT) and threshold intrinsic rotation reversal can be determined by collisionality. We NLT affected ECH, direction follows changes NLT. The significantly extended ECH. poloidal flow turbulence core plasma is ion diamagnetic ECH plasmas high OH plasma, respectively. auto-power spectra fluctuation are almost same outer region...
The overview of KSTAR activities on ICRH, LHCD and ECH/CD including the last experimental results future plan aiming for long-pulse high-beta plasma will be presented. Recently we achieved reasonable coupling ICRF power to H-mode through several efforts increase system reliability. Power balance discussed this experiment. is still struggling in low regime. Review antenna spectrum higher tried. provides 41 sec, 0.8 MW heating support high-performance discharge. Also, 170 GHz ECH integrated...
This paper presents a novel design of high self-interference cancellation (SIC) technique for microstrip antennas. The proposed antenna consists two closely-spaced orthogonal antennas with differential feeding as SIC circuit so to achieve interport isolation between the transmitter and receiver. In order RF leakage cancellation, network (DFN) is also in this paper, which provides amplitude out-of-phase imbalances within 0.12 ± 0.03dB -180 1°, respectively, bandwidth 500 MHz at center...
Abstract Detachment control based on ion saturation current I sat measurements from Langmuir probes (LPs) is implemented in the KSTAR tokamak and shown to be capable of following dynamic constant target trajectories with good accuracy, H-mode, by moderating flow rate nitrogen or deuterium. controllers normalize order form attachment fraction ( A frac ) as their parameter. The implementation differs previous work that it continuously calculates a model for attached uses denominator , whereas...
Multiple (two or more) flux tubes are commonly observed inside and/or near the q = 1 surface in KSTAR tokamak plasmas with localized electron cyclotron resonance heating and current drive (ECH/CD). Detailed 2D quasi-3D images of obtained by an advanced imaging diagnostic system showed that m/n 1/1 field-aligned structures co-rotating around magnetic axis. The typically merge together become like internal kink mode usual sawtooth, which then collapses a sawtooth crash. A systematic scan...
An 84-GHz, 500-kW electron cyclotron (EC) heating (ECH) system is under installation for ECH-assisted start-up in the Korea Superconducting Tokamak Advanced Research (KSTAR) facility. gyrotron, and 1.5-MVA power supply have been installed at KSTAR, initial test of gyrotron has carried out with a short-pulse condition 20 μs maximum beam parameters 80 kV 25 A that generate an output radio-frequency (rf) 500 kW. The planned 2-s-long operation rf beginning long-pulse supply. launcher was...
A novel design of compact negative group delay circuit (NGDC) using U-shaped defected ground structure (DGS) is presented in this paper. The required (GD) time can be controlled by an external resistor connected across the DGS slot. For experimental verification, a single stage NGDC designed, fabricated, and compared with simulation. To enhance NGD bandwidth, two stages different center frequencies cascade are demonstrated GD -3.8 ns maximum signal attenuation 37.10 dB was obtained on 3.45-3.55 GHz.
Abstract This paper proposes an X‐band quasi Class‐F high power amplifier (HPA) monolithic microwave integrated circuit (MMIC) using DynaFET gallium nitride (GaN) electron mobility transistor (HEMT) modelling. To enhance efficiency, a novel output matching is proposed. modelling for GaN HEMT utilized accurate HPA MMIC design. The proposed MMIC, fabricated ETRI's 0.15 µm process, achieves of 43.5∼44.5 dBm with power‐added efficiency 36∼40.7% within the 9.1∼10.3 GHz frequency bandwidth.
In this paper, we examine the robust beamforming design to tackle energy efficiency (EE) maximization problem in a 5G massive multiple-input multiple-output (MIMO)-non-orthogonal multiple access (NOMA) downlink system with imperfect channel state information (CSI) at base station. A novel joint user pairing and dynamic power allocation (JUPDPA) algorithm is proposed minimize inter interference also enhance fairness between users. This work assumes CSI by adding uncertainties matrices...
For a high-performance, advanced tokamak mode in KSTAR, we have been developing real-time control system of MHD modes such as sawtooth and Neo-classical Tearing Mode (NTM) by ECH/ECCD. The active feedback loop will be also added to the mirror position detection position. In this year, for stabilization NTM that is crucial plasma performance implemented open-loop ECH antenna KSTAR Plasma Control System (PCS) movement during single discharge. 170 GHz launcher which was designed fabricated...