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Kim, C.J.,Kim, Y.J.,Lim, C.Y.,Jun, B.H.,Park, S.D.,Choo, K.N. The Korea Institute of Applied Superconductivity a 2014 한국초전도저온공학회논문지 Vol.16 No.2
Temperature dependence of magnetic moment (m-T) and the magnetization (M-H) at 5 K and 20 K of the in situ processed $MgB_2$ bulk pellets with/without carbon (C) doping were examined. The superconducting critical temperature ($T_c$), the superconducting transition width (${\delta}T$) and the critical current density ($J_c$) were estimated for ten test samples taken from the $MgB_2$ bulk pellets. The reliable m-T characteristics associated with the uniform $MgB_2$ formation were obtained for both $MgB_2$ pellets. The $T_cs$ and ${\delta}Ts$ of all test samples of the undoped $MgB_2$ were the same each other as 37.5 K and 1.5 K, respectively. The $T_cs$ and ${\delta}Ts$ of the C-doped $MgB_2$ were 36.5 K and 2.5 K, respectively. Unlike the m-T characteristics, there existed the difference among the M-H curves of the test samples, which might be caused by the microstructure variation. In spite of the slight $T_c$ decrease, the C doping was effective in enhancing the $J_c$ at 5 K.
Kim, Y.H.,Kim, C.J.,Jun, B.H.,Sung, T.H.,Han, Y.H.,Han, S.C.,Paik, H.J.,Youn, J.S.,No, K. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15
Rare-earth (RE) (e.g. Sm, Dy, Ce, etc.) doping has been widely investigated to improve critical current density (J<SUB>c</SUB>) of YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-X</SUB> (YBCO) coated conductors (CC). Oxygen partial pressure is known to be a key parameter in terms of affecting the J<SUB>c</SUB> of YBCO films. In this work, the effect of oxygen partial pressure on the microstructure and J<SUB>c</SUB> of a Ce doped YBCO film was examined. Ce doped YBCO films were deposited on (100) SrTiO<SUB>3</SUB> (STO) single crystal substrates at oxygen partial pressures of 2.5, 5.0, and 10.0Torr using a metal organic chemical vapor deposition (MOCVD) method. Due to the enhanced migration of surface adatoms under reduced oxygen partial pressure, a 1wt% Ce doped YBCO film had a stoichiometric, dense surface. In addition, the zero-field J<SUB>c</SUB> (at 77K) of the 1wt% Ce doped YBCO film deposited at reduced oxygen partial pressure was increased. Irrespective of the amount of Ce, the Ce doped YBCO film showed an increased zero-field J<SUB>c</SUB> (at 77K) under reduced oxygen partial pressure.
Bae, J.W.,Kang, S.H.,Lee, Y.J.,Jun, K.W. Korean Society of Industrial and Engineering Chemi 2009 Journal of industrial and engineering chemistry Vol.15 No.4
The synthesis of dimethyl ether (DME) from biomass-derived model synthesis gas has been investigated on Cu-ZnO-Al<SUB>2</SUB>O<SUB>3</SUB>/Zr-ferrierite bifunctional catalysts. The catalysts are prepared by co-precipitation-impregnation method using Na<SUB>2</SUB>CO<SUB>3</SUB>, K<SUB>2</SUB>CO<SUB>3</SUB> and (NH<SUB>4</SUB>)<SUB>2</SUB>CO<SUB>3</SUB> as the precipitants. The catalytic activity tests reveal that the best yield of DME can be obtained on the catalyst precipitated by using (NH<SUB>4</SUB>)<SUB>2</SUB>CO<SUB>3</SUB>. Detailed characterization studies conducted on the catalysts to measure their properties such as surface area, acidity by temperature-programmed desorption of ammonia (NH<SUB>3</SUB>-TPD), reducibility of Cu oxide by temperature-programmed reduction (TPR), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and copper surface area and particle size measurements by N<SUB>2</SUB>O titration method. Increasing the number of moderate acidic sites and facilitation of easily reducible copper species with small particle size are found to be the prime reasons for the superior functionality of the (NH<SUB>4</SUB>)<SUB>2</SUB>CO<SUB>3</SUB> precipitated catalyst. The usage of (NH<SUB>4</SUB>)<SUB>2</SUB>CO<SUB>3</SUB> also leaves no residual ions, whereas the presence of residual K<SUP>+</SUP> and Na<SUP>+</SUP> ions in the case of K<SUB>2</SUB>CO<SUB>3</SUB> and Na<SUB>2</SUB>CO<SUB>3</SUB> precipitated catalysts leads to lower activity and selectivity.
기체 확산 전극을 이용한 이산화탄소의 전기 화학적 환원
임준혁,이경란,김진아,이제근,박정훈,전해수 한국공업화학회 1998 응용화학 Vol.2 No.2
The electrochemical reduction of carbon dioxide to produce alcohols and hydrocarbons has been examined on Cu/PTFE-bonded gas diffusion electrodes. The highest faradaic efficiencies for carbon monoxide, methante, ethylene, methanol and ethanol were 19.3, 12.4, 8.7, 7.3 and 3.8%, respectively. The faradaic efficiency and selectivity for the reduction products were dependent on operating conditions. Best results were found in -2.0 V vs. SCE and KHCO₃ electrolyte.
Youn, J.S.,No, K.,Kim, Y.H.,Mahmood, A.,Jun, B.H.,Han, Y.H.,Sung, T.H.,Kim, C.J. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15
To understand the effect of BaCeO<SUB>3</SUB> on a Y<SUB>2</SUB>BaCuO<SUB>5</SUB> (Y211) distribution, Y<SUB>1.5</SUB>Ba<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>x</SUB> (Y1.5) superconductors with/without 1wt.% BaCeO<SUB>3</SUB> additions were prepared by a top-seeded melt-textured growth (TSMG) process. Two different BaCeO<SUB>3</SUB> powders (as-synthesized (coarse powder) and an attrition-milled (fine powder)) were used and the size effect was compared with that obtained from a Y1.5 sample with no addition. A refinement of the Y211 particles was achieved for both the as-synthesized and attrition-milled BaCeO<SUB>3</SUB> additions. The distribution of the Y211 particles was most uniform in the Y1.5 sample prepared with the attrition-milled BaCeO<SUB>3</SUB> powder due to the reduced size of the Y211-free regions by the fine size BaCeO<SUB>3</SUB> addition. The highest J<SUB>c</SUB> was achieved in the Y1.5 sample prepared with the attrition-milled BaCeO<SUB>3</SUB> powder. The J<SUB>c</SUB> result agreed well with the microstructure variations by the addition of BaCeO<SUB>3</SUB> powders.
Pore formation in in situ processed MgB<sub>2</sub> superconductors
Yi, J.H.,Kim, K.T.,Jun, B.H.,Sohn, J.M.,Kim, B.G.,Joo, J.,Kim, C.J. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15
MgB<SUB>2</SUB> bulks were prepared by an in situ process which utilizes the reaction between boron and magnesium powder. The reaction time was fixed at 0.5h and the temperature was changed from 600<SUP>o</SUP>C to 1000<SUP>o</SUP>C. The density decrease due to pore formation and mass (mainly magnesium) loss during the formation reaction of MgB<SUB>2</SUB> was observed in all samples. In addition to the pore formation, a pellet expansion which can be explained by the outgrowth of MgB<SUB>2</SUB> grains was also observed. Two different mechanisms were adopted to explain the pore formation; Kirkendall pores formed at a temperature below the melting point (m.p.) of magnesium by a difference in the diffusivity between magnesium and boron, and the pores formed at a temperature above the m.p. by melting of magnesium and a capillary movement. The density, T<SUB>c</SUB> and J<SUB>c</SUB> results suggest that the current carrying capacity can be improved by a careful control of the process parameters regarding a pore evolution.
권광진,전재억,정진서,황영모,박후명,하만경 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-
Ratio that robot occupies is low level worldwide fairly in susdension wire, electricity electron and neutralization learning industry and domestic industry of this is staying in average leve. Can speak that grafting of robotic machine and neutralization learning industry is high in terms of side of creation of the added value or progress of technology rightly hereupon. This research raises or designed multi-function handling robot that can make welding, assembly conveniently catching large size work water
Kim, M.,Jun, H.-K.,Choi, B.-K.,Cha, J.-H.,Yoo, Y.-J. Blackwell Publishing Ltd 2010 Journal of periodontal research Vol.45 No.6
<P><I>Kim M, Jun H-K, Choi B-K, Cha J-H, Yoo Y-J. Td92, an outer membrane protein of</I> Treponema denticola<I>, induces osteoclastogenesis via prostaglandin E</I><SUB><I>2</I></SUB><I>-mediated RANKL/osteoprotegerin regulation. J Periodont Res 2010; 45: 772–779. © 2010 John Wiley & Sons A/S</I></P><P>Background and Objective: </P><P>Periodontitis is a chronic inflammatory disease of the periodontium that causes significant alveolar bone loss. Osteoclasts are bone-resorbing multinucleated cells. Osteoblasts regulate osteoclast differentiation by expression of RANKL and osteoprotegerin (OPG). Td92 is a surface-exposed outer membrane protein of <I>Treponema denticola</I>, a periodontopathogen. Although it has been demonstrated that Td92 acts as a stimulator of various proinflammatory mediators, the role of Td92 in alveolar bone resorption remains unclear. Therefore, in this study, we investigated the role of Td92 in bone resorption.</P><P>Material and Methods: </P><P>Mouse bone marrow cells were co-cultured with calvariae-derived osteoblasts in the presence or absence of Td92. Osteoclast formation was assessed by TRAP staining. Expressions of RANKL, osteoprotegerin (OPG) and prostaglandin E<SUB>2</SUB> (PGE<SUB>2</SUB>) in osteoblasts were estimated by ELISA.</P><P>Results: </P><P>Td92 induced osteoclast formation in the co-cultures. In the osteoblasts, RANKL and PGE<SUB>2</SUB> expressions were up-regulated, whereas OPG expression was down-regulated by Td92. The addition of OPG inhibited Td92-induced osteoclast formation. The prostaglandin synthesis inhibitors NS398 and indomethacin were also shown to inhibit Td92-induced osteoclast formation. The effects of Td92 on the expressions of RANKL, OPG and PGE<SUB>2</SUB> in osteoblasts were blocked by NS398 or indomethacin.</P><P>Conclusion: </P><P>These results suggest that Td92 promotes osteoclast formation through the regulation of RANKL and OPG production via a PGE<SUB>2</SUB>-dependent mechanism.</P>