Jong-Gu Kwak

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Edge localized modes (ELMs) in high-confinement mode plasmas were completely suppressed in KSTAR by applying n=1 nonaxisymmetric magnetic perturbations. Initially, the ELMs were intensified with a reduction of frequency, but completely suppressed later. The electron density had an initial 10% decrease followed by a gradual increase as ELMs were suppressed.(More)
Site-directed mutagenesis studies of bovine pancreatic phospholipase A2 (PLA2, overproduced in Escherichia coli) showed that replacement of surface residue Lys-56 by a neutral or hydrophobic amino acid residue resulted in an unexpected and significant change in the function of the enzyme. The kcat for phosphatidylcholine micelles increases 3-4-fold for(More)
BACKGROUND Insufflation of carbon dioxide (CO(2)) to the operative field has been used to prevent major organ injury attributed to air embolisms in cardiac surgery. However, it may be preferable to avoid hypercapnia induced by CO(2) insufflation, owing to its potentially harmful effect. To investigate the effectiveness of near-infrared spectroscopy (NIRS)(More)
A long pulse plasma discharge experiment was carried out using RF heating power in the Large Helical Device (LHD), a currentless magnetic confining system. Progress in long pulse operation is summarized since the 10 experimental campaign (2006). A scaling relation of the plasma duration time to the applied RF power has been derived from the experimental(More)
An ion cyclotron range of frequency system requires rf diagnostics for a rf-plasma coupling or for maintaining a correct operation. A detector based on a digital I/Q demodulation technique collects the rf amplitude and phase at the same time without errors from the I/Q imbalance inherent in an analog counterpart. The theory of such a detector was studied(More)
A wave detector, a newly designed magnetic probe, is installed in the large helical device (LHD). This wave detector is a 100-turn loop coil with electrostatic shield. Comparing a one-loop coil to this detector, this detector has roughly constant power coupling in the lower frequency range of 40 MHz, and it can easily detect magnetic wave in the frequency(More)
It is observed that the magnitude of the toroidal rotation speed is reduced by the central electron cyclotron resonance heating (ECRH) regardless of the direction of the toroidal rotation. The magnetohydrodynamics activities generally appear with the rotation change due to ECRH. It is shown that the internal kink mode is induced by the central ECRH and(More)
Measuring rotation profiles with a reliable spatial resolution is one of the critical diagnostics in understanding the plasma behavior especially for the edge transport. In the KSTAR experiments, it has been consistently observed from the charge exchange spectroscopy measurements that the magnetic perturbations not only suppresses edge localized modes(More)
Characteristics of a complex-conjugate impedance antenna system for ICRF (ion cyclotron resonance frequency) heating are discussed in this paper. Large RF power is reflected in such transition as that of ELMy H-L mode because of the big change in the plasma resistance for ICRF heating. In such a case the RF power injection to the plasma is ceased to protect(More)
Electron heating regime using with radio-frequency waves in the ion cyclotron range of frequencies (ICRF) has been investigated in helical magnetic configuration. Mode-conversion scenario was applied to the LHD plasmas. When the wave frequency is change to be lower than that in the standard ICRF heating (minority ion heating) condition, the resonance layers(More)