Geochronological and geochemical implications of Early to Middle Jurassic continental adakitic arc magmatism in the Korean Peninsula

Kim, S.W.,Kwon, S.,Ko, K.,Yi, K.,Cho, D.L.,Kee, W.S.,Kim, B.C. Universitetsforlaget ; Elsevier Science Ltd 2015 Lithos Vol.227 No.-

Sensitive high-resolution ion microprobe (SHRIMP) zircon U-Pb ages and whole-rock chemical compositions of Early to Middle Jurassic plutons from the central to southern Korean Peninsula are reported to investigate the effect of paleo-Pacific plate subduction preserved along the continental margin. Twenty-one plutonic rocks from the Yeongnam massif (i.e., Sunchang and Namwon plutons), the Okcheon belt (Jeongup, Boeun, and Mungyeong plutons), the northeast (Gangreung pluton), and the Gyeonggi massif (Gonam, Anheung, and Ganghwa plutons) have age ranges from ca. 189-186Ma to 177Ma, 177-166Ma, and 177-173Ma, respectively. Most plutonic rocks have chemical compositions similar to adakites, showing high SiO<SUB>2</SUB> (45.62-74.96wt.%), low MgO (0.01-2.84wt.%), high Na<SUB>2</SUB>O (2.65-4.83wt.%), high Sr/Y and La/Yb, low Y and Yb, as well as low HFSEs (Nb and Ta), but initial Sr ratios (0.7048-0.7262), K<SUB>2</SUB>O (0.50-5.88wt.%), and K<SUB>2</SUB>O/Na<SUB>2</SUB>O (0.34-2.1) were unlikely to have been formed by melting of either a thickened and/or delaminated lower continental crust, or an altered oceanic crust. These suggest that the ''adakitic'' plutonic rocks in this region resulted from partial melting of an enriched mantle source metasomatized by dewatering from a delaminated flat-slab. The spatial distributions of this continental adakitic plutonic belt, based on the present study, together with previously reported geochronological results, indicate that magmatic pulses gradually migrated toward the continent across the Korean Peninsula as a result of slab shallowing caused by periodic slab buckling. The similar geochronological and geochemical characteristics, petrogenesis and tectonic setting of the plutonic belt spanning the Korean Peninsula, Japan, eastern China, and eastern Russia indicate a possible link to an active subduction system that existed during the Early to Middle Jurassic, although the products of the plate subduction might differ in different locations along the East Asian continental margin.

Search for the H Dibaryon in (K-, K+) Reactions

Bahk,S. Y.,Chung,K. S,Chung,S. H.,Funahashi,H.,Hahn,C. H.,Hara,T.,Hirata,S.,Hoshino,K.,Ieiri,M.,Iijima,T.,Imai,K.,Ishigami,T.,Itow,Y.,Kazuno,M.,Kikuchi,K.,Kim,C. O.,Kim,D. C.,Kim,J. Y.,Kobayashi,M.,Ko 國立昌原大學校 基礎科學硏究所 1992 基礎科學硏究所論文集 Vol.3 No.-

We have studied(??) reactions from an emulsion target. The S--2H dibaryon has been searched for by the analysis of the ??? momentum spectrum together with emulsion data. No evidence of H production was observed in the mass range of 1.90-2.16 GeV/c². Upper limits for the production cross section of the H are (0.2-0.6)% of that for the quasifree ??? production at the 90% confidence level.

Comparative Analysis of Different Grain Configurations for a Multi-thruster Kinetic Warhead

N. Ananthkrishnan,Hyun Ko,K. Sreesankar,R. Chakravarty,V.S. Renganathan 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.5

The S-DACS multi-thruster warhead consists of 4 divert and 6 attitude thrusters fed from a common gas generator. Successful S-DACS intercept requires careful selection of the internal ballistics (grain configuration, chamber pressure, etc.), the sensors (seeker range, guidance law, etc.) as well as the external ballistics and sizing (booster diameter, S-DACS release velocity, flight time, maneuverability, etc.). These requirements and constraints are inter-dependent making the S-DACS mission analysis and sizing a difficult task. This work explores the connections between the choice of S-DACS grain configuration and sizing with the chamber pressure as a key parameter. Various parameters and center of gravity/ moment of inertia variations are compared for three different S-DACS grain configurations. Keywords: DACS, grain configuration, mission analysis

Wall teichoic acid is an essential component of Staphylococcus aureus for the induction of human dendritic cell maturation

Hong, S.J.,Kim, S.K.,Ko, E.B.,Yun, C.H.,Han, S.H. Pergamon Press 2017 Molecular immunology Vol.81 No.-

<P>Staphylococcus aureus is a Gram-positive pathogen that can cause chronic skin inflammation, pneumonia, and septic shock. The immunomodulatory functions of wall teichoic acid (WTA), a glycopolymer abundantly expressed on the Gram-positive bacterial cell wall, are poorly understood. Here, we investigated the role of WTA in the phenotypic and functional activation of human monocyte-derived dendritic cells (DCs) treated with ethanol-killed S. aureus. WTA-deficient S. aureus mutant (Delta tagO) exhibited attenuated binding and internalization to DCs compared to the wild-type. Delta tagO induced lower expression of maturation markers on and cytokines in DCs than the wild-type S. aureus. Furthermore, autologous human peripheral blood mononuclear cells cocultured with Delta tagO-treated DCs exhibited a marked reduction in T cell proliferative activity, the expression of activation markers, and the production of cytokines compared to the wild-type S. aureus-stimulated DCs. Collectively, these results suggest that WTA is an important cell wall component of S. aureus for the induction of DC maturation and activation. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Overview of KSTAR research progress and future plans toward ITER and K-DEMO

Park, H.K.,Choi, M.J.,Hong, S.H.,In, Y.,Jeon, Y.M.,Ko, J.S.,Ko, W.H.,Kwak, J.G.,Kwon, J.M.,Lee, J.,Lee, J.H.,Lee, W.,Nam, Y.B.,Oh, Y.K.,Park, B.H.,Park, J.K.,Park, Y.S.,Wang, S.J.,Yoo, M.,Yoon, S.W.,B IOP 2019 Nuclear fusion Vol.59 No.11

<P>A decade-long operation of the Korean Superconducting Tokamak Advanced Research (KSTAR) has contributed significantly to the operation of superconducting tokamak devices and the advancement of tokamak physics which will be beneficial for the ITER and K-DEMO programs. Even with limited heating capability, various conventional as well as new operating regimes have been explored and have achieved improved performance. As examples, a long pulse high-confinement mode operation with and without an edge-localized mode (ELM) crash was well over 70 and 30 s, respectively. The unique capabilities of KSTAR allowed it to improve the capability of controlling harmful instabilities, and they have been instrumental in uncovering much new physics. The highlights are that the L/H transition threshold power is sensitive to the resonant magnetic perturbation (RMP) and insensitive to non-resonant magnetic perturbation. Co-<I>I</I> <SUB>p</SUB> offset rotation dominated by an electron channel predicted by general neoclassical toroidal viscosity theory was confirmed. Improved heat dispersal in a divertor system using three rows of rotating RMP was demonstrated and predictive control of the ELM-crash with <I>a priori</I> modeling was successfully tested. In magnetohydrodynamic physics, validation of the full reconnection model (i.e. <I>q</I> <SUB>0</SUB>  >  1 right after the sawtooth crash) and self-consistent validation of the anisotropic distribution of turbulence amplitude and flow in the presence of the 2/1 island with theoretical models were achieved. The turbulence amplitude induced by RMP was linearly increased with the slow RMP coil current ramp-up time (i.e. the magnetic diffusion time scale). The <I>D</I> <SUB> <I>α</I> </SUB> spikes (i.e. ELM-crash amplitude) was linearly decreased with the turbulence amplitude and not correlated with the perpendicular electron flow. In the turbulence area, a non-diffusive ‘avalanche’ transport event and the role of a quiescent coherent mode in confinement were studied. To accommodate the anticipation of a higher performance of the KSTAR plasmas with the increased heating powers, a new divertor/internal interface with a full active cooling system will be implemented after a full test of the new heating (neutral beam injection II and electron cyclotron heating) and current drive (CD) (Helicon and lower hybrid CD) systems. An upgrade plan for the internal hardware, heating systems and efficient CD system may allow for a long pulse operation of higher performance plasmas at <I>β</I> <SUB>N</SUB>  >  3.0 with <I>f</I> <SUB>bs</SUB> ~ 0.5 and <I>T</I> <SUB>i</SUB>  >  10 keV.</P>

Emergence of an extended-spectrum <i>β</i>-lactamase-producing serotype K1 <i>Klebsiella pneumoniae</i> ST23 strain from Asian countries

CHEONG, H. S.,CHUNG, D. R.,PARK, M.,KIM, S. H.,KO, K. S.,HA, Y. E.,KANG, C. I.,PECK, K. R.,SONG, J. H. Cambridge University Press 2017 Epidemiology and infection Vol.145 No.5

<B>SUMMARY</B><P>Extended-spectrum <I>β</I>-lactamase (ESBL) production has been very rare in serotype K1 <I>Klebsiella pneumoniae</I> ST23 strains, which are well-known invasive community strains. Among 92 ESBL-producing strains identified in 218 isolates from nine Asian countries, serotype K1 <I>K. pneumoniae</I> strains were screened. Two ESBL-producing <I>K. pneumoniae</I> isolates from Singapore and Indonesia were determined to be serotype K1 and ST23. Their plasmids, which contain CTX-M-15 genes, are transferable rendering the effective transfer of ESBL resistance plasmids to other organisms.</P>

Single-stranded DNA aptamer that specifically binds to the influenza virus NS1 protein suppresses interferon antagonism

Woo, H.M.,Kim, K.S.,Lee, J.M.,Shim, H.S.,Cho, S.J.,Lee, W.K.,Ko, H.W.,Keum, Y.S.,Kim, S.Y.,Pathinayake, P.,Kim, C.J.,Jeong, Y.J. Elsevier/North-Holland 2013 Antiviral research Vol.100 No.2

Non-structural protein 1 (NS1) of the influenza A virus (IAV) inhibits the host's innate immune response by suppressing the induction of interferons (IFNs). Therefore, blocking NS1 activity can be a potential strategy in the development of antiviral agents against IAV infection. In the present study, we selected a single-stranded DNA aptamer specific to the IAV NS1 protein after 15 cycles of systematic evolution of ligands by exponential enrichment (SELEX) procedure and examined the ability of the selected aptamer to inhibit the function of NS1. The selected aptamer binds to NS1 with a K<SUB>d</SUB> of 18.91+/-3.95nM and RNA binding domain of NS1 is determined to be critical for the aptamer binding. The aptamer has a G-rich sequence in the random sequence region and forms a G-quadruplex structure. The localization of the aptamer bound to NS1 in cells was determined by confocal images, and flow cytometry analysis further demonstrated that the selected aptamer binds specifically to NS1. In addition, luciferase reporter gene assay, quantitative RT-PCR, and enzyme-linked immunosorbent assay (ELISA) experiments demonstrated that the selected aptamer had the ability to induce IFN-β by suppressing the function of NS1. Importantly, we also found that the selected aptamer was able to inhibit the viral replication without affecting cell viability. These results indicate that the selected ssDNA aptamer has strong potential to be further developed as a therapeutic agent against IAV.

Current Status of the KSTAR TF Superconducting Magnet Development

ByoungSu Lim,C. S. Kim,D. J. Kim,D. K. Lee,G. S. Lee,H. K. Park,I. S. Woo,J. S. Bak,J. Y. Choi,J.J. Joo,K. Pak,K. Kim,K. P. Kim,M. S. Ko,N. H. Song,S. Lee,S. J. An,W. Chung,W. W. Park,Y. J. Song 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III

The KSTAR (Korea Superconducting Tokamak Advanced Research) TF magnet system is a fully superconducting magnet system which consists of 16 TF coils. The TF coil system provides a field of 3.5 T at a plasma center, with a peak flux density at the TF coils of 7.5 T. The stored energy is 470 MJ. TF coils use a Nb3Sn superconducting strand with Incoloy alloy 908 (afterward, Incoloy 908) conduit. The Nb3Sn strand has KSTAR HP-III specifications in which the critical current density is greater than 750 A/mm2 at 12 T, 4.2 K. The nominal current of the TF coils is 35.2 kA with all coils in series. For the fabrication of CICC (Cable-In-Conduit Conductor), a continuous CICC jacketing system is developed, and the procedures of coil fabrication are established to develop the TF coil. The prototype TF coil and the TF 01 16 coils are fabricated for the KSTAR superconducting magnet system. The TF17 coil which will be used as a back up coil is under fabrication. The overall TF coil fabrication will be completed by the end of December 2005.=

Key Features in the Operation of KSTAR

Jong-Gu Kwak,Oh, Y. K.,Kim, K. P.,Kim, S. W.,Hong, S. H.,Chu, Y.,Lee, H. J.,Kim, Y. O.,Kim, J.,Park, S. L.,Hahn, S. H.,Park, M. K.,Kim, H. K.,Bak, J. G.,Bae, Y. S.,Ko, W. H.,Lee, S. G.,Lee, J. H.,Jung IEEE 2012 IEEE transactions on plasma science Vol.40 No.3

<P>The Korea Superconducting Tokamak Advanced Research (KSTAR) device is aimed at advanced tokamak (AT) research. Three years have passed since it achieved its first plasma in 2008. Because it is a superconducting machine and is working toward AT research, it has unique features in terms of the machine engineering and operation. The toroidal field (TF) magnet coils are made of Nb<SUB>3</SUB>Sn, which provide high TFs up to 3.5 T, and have been fully tested. The poloidal field (PF) magnet coils, consisting of both Nb<SUB>3</SUB>Sn and NbTi, which have a maximum current of 25 kA in their design, were tested up to 15 kA. A thermal hydraulic analysis is being conducted for PF magnet coil operation. All plasma-facing components (PFCs) are equipped with water cooled graphite tiles and have the capability of being baked up to 350°C. A startup scenario, which considered both the effect of the ferromagnetic material in the cable in conduit conductor jacket of the magnet coils as well as a nonferromagnetic up-down asymmetry in the cryostat structure, was developed and demonstrated its effectiveness by the last two year's reliable operations. Passive stabilizers and in-vessel control coils (IVCCs) are key components to realize AT operation in KSTAR. The segmented IVCC coils were connected to form circular coils for internal vertical control in 2010, and diverted plasmas with high elongation (κ~1.8, δ>;0.6) were achieved. A neutral beam injection (NBI) system was developed aiming at 2 MW, 300 s per ion source which meets the long-pulse requirement of KSTAR. An NBI ion source with a power of 1.7 MW at 100 kV has been commissioned for 10 s. Finally, ELMy H-modes were successfully produced with 1.3-MW NBI power at a plasma current of 0.6 MA in the 2010 campaign. The first H-mode discharge (#4200) in KSTAR was achieved one year earlier than officially planned and was done at B<SUB>T</SUB> = 2 T with I<SUB>p</SUB> = 0.6 MA in a well-balanced double null configuration after boronization on the PFC. Successful operations in the early days of KSTAR including H-mode experiments revealed the capability of advanced and steady-state operation which is essential for the international thermonuclear experimental reactor (ITER) and future fusion reactors.</P>

γ-Ray-induced synthesis and electrochemical properties of a mesoporous layer-structured α-Co(OH)₂ for supercapacitor applications

Ko, J.M.,Soundarajan, D.,Park, J.H.,Yang, S.D.,Kim, S.W.,Kim, K.M.,Yu, K.H. Elsevier 2012 Current Applied Physics Vol.12 No.1

α-Cobalt hydroxide is synthesized through a novel radiation-induced route using a cobalt nitrate hexahydrate isopropanol solution by irradiating <SUP>60</SUP>Co γ-rays. The as-prepared product shows a layer-structured mesoporous morphology with an average size of 250 nm. Crystalline property analysis exhibits the presence α-Co(OH)<SUB>2</SUB> as a predominant phase with a tiny amount of secondary phases of β-Co(OH)<SUB>2</SUB> and CoO. X-ray photoelectron spectroscopy discloses the existence of Co as Co(OH)<SUB>2</SUB> and CoO with a stoichiometric ratio of 76.7:23.3. In addition, the supercapacitive properties of the product are investigated using cyclic voltammetry and impedance spectroscopy in 1M KOH aqueous solution, showing a maximum capacitance value of 246.7 F g<SUP>-1</SUP> at a scan rate of 5 mV s<SUP>-1</SUP>.