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Kwak, T.Y.,Lim, H.K.,Kim, W.J. Elsevier Sequoia 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.658 No.-
The hot compressive characteristics and processing maps of the extruded 0.5 wt.% Ca-AZ31 (Ca-AZ31) alloy and the extruded AZ31 alloy were examined and compared in the temperature range between 473 and 673 K and in the strain rate range between 10<SUP>-3</SUP> and 10 s<SUP>-1</SUP>. The extruded Ca-AZ31 alloy had a smaller grain size (10.64 vs. 23.44 μm) and a more homogeneous microstructure than the extruded AZ31 alloy due to the presence of thermally stable Al<SUB>2</SUB>Ca particles in the former. The addition of 0.5 wt.% Ca increased the ignition temperature of AZ31 by 270.5 K. While the added Ca did not affect the activation energy for plastic flow, it slightly decreased the stress exponent and increased the flow stress level. Dislocation climb creep associated with stress exponents of 5-7 dominated the plastic flow of the extruded AZ31 and extruded Ca-AZ31 alloys. The power-law breakdown did not appear in either alloy under the given testing conditions. In comparison with the extruded AZ31 alloy, the extruded Ca-AZ31 alloy exhibited a poor hot workability at low temperatures below 523 K. However, there was an improved hot workability at higher temperatures due to the presence of the Al<SUB>2</SUB>Ca particles that promoted dynamic recrystallization (DRX) and retarded coarsening of the DRXed grains. Compared with the extruded Ca-AZ31 alloy, the cast Ca-AZ31 alloy with a much larger grain size (86.2 μm) and a coarser secondary phase structure exhibited a poor hot workability at high strain rates (10<SUP>-1</SUP>-10<SUP>0</SUP> s<SUP>-1</SUP>) over the entire testing temperature range due to the occurrence of unstable flow.
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Pichia pastoris(Methylotrophic Yeast)를 이용한 항균성 양이온 펩타이드의 발현
조광근,최윤재,복진덕,이강우,곽성욱,우정희,성창근 한국동물자원과학회 2001 한국축산학회지 Vol.43 No.4
Antimicrobial cationic peptides have been received increasing attention as natural antibiotics for their broad spectrum of antimicrobial activities and remarkably low cytotoxicity against normal mammalian cells. Pichia pastoris, a methylotrophic yeast, is an outstanding host for high degree of heterologous gene expression. Four candidates of antimicrobial cation peptides (CPs; Lactofemicin, Magainin, Protegrin-1 and Indolicidin) were expressed using pPIC9K-MPM vector containing AOXI promoter and MPM (modified Promagainin) as an acidic fusion partner. The MPM-CPs were expressed and induced by methanol induction method. The cell extracts, solubilized, were subjected to cyanogen bromide cleavage. SDS-PAGE (16.5% tricine) analysis showed the size of Protegrin-1 at 2.1kDa and of Indolicidin at 1.4kDa. The antimicrobial activity of Protegrin-1 or Indolicidin gene integrated transformant was observed by measuring clearing zones on 1% bacto-peptone agar plate against Gram-negative bacteria Escherichia coli XL-1 blue (10^5 CFU/㎖) or Gram-positive bacteria Staphylococcus aureus (10^5 CFU/㎖).
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Kim, K.,Kim, I.,Maiti, N.,Kwon, S.J.,Bucella, D.,Egorova, O.A.,Lee, Y.S.,Kwak, J.,Churchill, D.G. Pergamon Press 2009 Polyhedron Vol.28 No.12
Herein the synthesis and binding studies of novel trans-A<SUB>2</SUB>B-corrole and trans-A<SUB>2</SUB>B<SUB>2</SUB>-porphyrin derivatives are presented in comparing manganese(III)-organophosphonate (OP) binding (e.g., M<SUP>n+</SUP>←O?PR(OR)<SUB>2</SUB>) capabilities. H<SUB>3</SUB>(PFP-VC) [PFP-VC=5,15-di(pentafluorophenyl)-10-(3-vinylphenyl)corrolate] was synthesized by way of literature procedures and was characterized by a variety of 2-D NMR spectroscopic techniques and single-crystal X-ray diffraction. These compounds represent the first example of 3-vinyl-phenyl-containing meso-substituted corroles or porphyrins. Mn(PFP-VC) (3) was treated separately with (CH<SUB>3</SUB>CH<SUB>2</SUB>O)<SUB>2</SUB>P?O(C<SUB>3</SUB>H<SUB>6</SUB>NMe<SUB>2</SUB>), (C<SUB>4</SUB>H<SUB>9</SUB>O)<SUB>2</SUB>P?O(Me), (C<SUB>2</SUB>H<SUB>5</SUB>O)<SUB>2</SUB>P?O(CH<SUB>2</SUB>COCH<SUB>3</SUB>), (CH<SUB>3</SUB>CH<SUB>2</SUB>O)<SUB>2</SUB>P?O(Me), to give 1:1 adducts, as determined by UV-Vis spectroscopy (Job Plot), giving a red shift; Ph<SUB>3</SUB>P?O, was also found to bind, but very weakly. The trans-A<SUB>2</SUB>B<SUB>2</SUB>-porphyrin analogue Mn(PFP-VP) (4) was also prepared by way of a literature procedure; related binding studies gave 1:1 organophosphonate-Mn(PFP-VP) adducts (Job Plot). A clean blue shift occurred for the Mn-porphyrins at higher organophosphonate loadings (K<SUB>a</SUB> values: 6.7 (0.9)-11.9 (0.4)M<SUP>-1</SUP>). DFT geometry optimizations of O?P(OMe)<SUB>2</SUB>Me binding and formal Mn-O or P-O cleavage products in the unsubstituted neutral Mn-corrolato and -porphyrinato systems with a range of metal-based spin states revealed greatest stability in formal phosphoryl oxygen binding (energies: 11-13kcal/mol) for the Mn-corrole (singlet); the Mn-porphyrin (sextet) was also quite stable.
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이경희,한현석,윤효근,부진효,이순보,곽현태 성균관대학교 기초과학연구소 1998 論文集 Vol.49 No.-
The coadsorption of CO and O₂ on W(110) surface was studied by LEED, TDS, and photoelectron spectroscopy. In the TDS for the coadsorption of CO at RT on O₂ precovered W(110) surface, two CO desorption states were observed at about 400 and 1150 K, called α and β , respectively. The β-CO spectra with second order desorption kinetics were shifted to lower desorption temperature as increasing the amount of preadsorbed atomic oxygen on the W(110). Moreover, the β-CO spectra were gradually increased with increasing the amount of preadsorbed oxygen to 0.5 ML. Even though a (2 x 1) LEED pattern appeared during oxygen adsorption at RT and 1-3 L oxygen exposures, we didn't observe any new pattern induced by CO in this study. Only the structure of c(11 x 5) was obtained at temperature in the range of 800-1100 K. These results indicated that there were interaction between CO and O and thereby the β-CO might riot be dissociated even at the higher temperature than 800 K. By using the XPS and UPS, it was also confirmed that the coadsorbed β-CO at 900 K doesn't dissociate as the experimental results of the adsorption of pure CO on W(110) surface at the same temperature. According to the valence band spectra, two CO peaks at near -10.7 eV (4σ) and -7.0 eV (5σ+1π) were observed, indicating molecular CO adsorption on the oxygen preadsorbed surface at RT. Even heating the coadsorbed surface to 900 K, we could also detect the CO 4σ peak which can be an important factor for identifying a contribution of the CO 4σ molecular orbital to the CO-metal bond. To our best knowledge, this is the first report and quite contradictory result to that reported previously.
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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>
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NDIR식 마이크로 스펙트로미터 적외선 센서용 저응력 SiNx Membrance 상에서의 최적화된 Thermopile 제조 및 특성
최공희,최광남,곽성관,김동식,정관수 경희대학교 레이저공학연구소 2005 레이저공학 Vol.16 No.-
Twenty four types of thermopile for micro spectrometer infrared sensors were fabricated on low-stress Si_(3)N_(4) membranes with 1.2㎛-thickness using MEMS technology. Thermopile were designed and fabricated for optimum conditions by five parameters of thermocouple numbers (16∼48), thermocouple line widths (10㎛∼25㎛), thermocouple lengths (100㎛∼500㎛), membrane areas (1^(2)㎟∼2.5^(2)㎟) and junction areas (150㎛^(2) 2∼750㎛^(2)), respectively. It was thought that measurement results could be used for thermopile infrared sensors optimum structure for micro spectrometers.
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