• Bulletin of the Korean Chemical Society
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• v.15 no.2
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• pp.126-132
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• 1994

RhCl [P($C_6H_5)_3]_3$ complexes have been incorporated in polysulfone (PS) as a dispersion medium using cosolvent (THF). The interactions between Rh(Ⅰ) complexes and polysulfone polymer molecules are examined by infrared spectroscopy and thermal analysis. The chemical reactivity of Rh in PS films has been investigated by reacting Rh sites with CO, $H_2,\;D_2,\;O_2\;NO,\;C_2H_2\;and\;C_2H_4$ in the temperature range $25-200^{\circ}C$. Various Rh-carbonyl, -hydride and -nitrosyl species formed in PS films are characterized by their infrared spectra. Rh complexes in PS film show interesting catalytic reactivities in the reactions such as hydrogenation of $C_2H_2\;and\;C_2H_4$, oxidation of CO, and reduction of NO by CO or $H_2$ gas under relatively mild conditions.

• Journal of the Korean Chemical Society
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• v.27 no.6
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• pp.434-440
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• 1983

New procedures for the reduction of carboxylic acids, carboxylic acid salts, tertiary amides, and sulfoxides with sodium borohydride and triphenyl borate in tetrahydrofuran were developed. Thus carboxylic acids were reduced quantitatively in 6∼12 h at $25^{\circ}C$. Alphatic acid salts were quantitatively reduced to the corresponding alcohols in 6h at $25^{\circ}C$ whereas aromatic acid salts required 24h at $65^{\circ}C$. Tertiary amides were reduced to the corresponding amines in 88∼100% yields in 3∼6h at room temperature. Most sulfoxides examined were reduced to the corresponding sulfides in 98∼100% yields in 1∼6h at $25^{\circ}C$ and completely reduced at $65^{\circ}C$; however, diphenyl sulfoxide required 48h in a more vigorous condition.

• Korean Journal of Crystallography
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• v.15 no.2
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• pp.93-98
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• 2004

The structure of C_{28}H_{41}N_4O_4Br\;{\cdot}\;2H_2O$ has been determined by X-ray deffraction methods. The crystal system is triclinic, space group Pl, unit cell constants, a=9.000(1) $\AA$, b=9.312(3) $\AA$, c=9.344(2) $\AA$, $\alpha=89.37(20)^{\circ},\;\beta=68.81(3)^{\circ},\;\gamma=84.70(4)^{\circ},\;V=726.7(8){\AA},\;T=298K,\;Z=1,\;D_c=1.402Mgm^{-3}$. The intensity data were collected on an Enraf-Nonius CAD4 Diffractometer with graphite monochromated $MoK\alpha$ radiation $(\lambda=0.71073\;{\AA}$. The molecular structure was solved by direct methods and refined by full-matrix least squares to a final $R=5.95\%$ for 2521 unique observed $F_0>4\sigma(F_0)$reflections and 370 parameters.

• Korean Journal of Food Science and Technology
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• v.21 no.3
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• pp.351-359
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• 1989

This study was conducted to observe the physico-chemical exchange and effect of amino-carbonyl reaction between fructose and glycine . When various buffer solutions were added to equimolar mixture of fructose and glycine at pH 6.0 and $100^{\circ}C$, the browning effect was markedly observed by Mcllvaine buffer. Among the combinations of temperature and reaction time, the deep browning effect was obtained above $100^{\circ}C$, 3hr A marked browning effect obtained above pH 7.0 but little observed below pH 7.0. The browning effect was markedly increased at high fructose concentration. It required 4.0hrs and 32.9hrs to decrease 50% of initial concentration of fructose and glycine at $100^{\circ}C$ and pH 7 but 0.9hrs and 3.8hrs at $120^{\circ}C$, pH 7.0, respectively. The rate constant of fructose and glycine at $100^{\circ}C\;and\;120^{\circ}C$ were $1.78{\times}10^{-1},\;2.11{\times}10^{-2}\;and\;7.74{\times}10^{-1},\;1.83{\times}10^{-1}$, respectively. The formation of HMF was likely to follow the first order kinetics. The addition of 0.1M sodium sulfite, 0.1M sodium bisulfite and 0.1M calcium chloride to equimolar mixture (0.05M) surpressed the reaction up to 76.8%, 76.8% and 96.4%, respectively.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.314-320
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• 1999

Several bisphosphine- and bisphosphite-substituted Re-imido complexes have been prepared from Re(NPh)(PPh3)2Cl3, 1, and Re(N-C6H3-i-Pr2)2Cl3(py), 4. Compound 1 reacted with trimethyl phosphate (P(OMe)3) to give a mixture of two isomers,mer,trans-Re(NPh)(P(OMe)3)2Cl3, 2, and fac,cis-Re(NPh)(P(OMe)3)2Cl3, 2a. In this reaction, the mer,trans-isomer is a major product. Complex 1 also reacted with triethylphosphine (PEt3) to exclusively give mertrans-Re(NPh)(PEt3)2Cl3, 3. Compound 4 reacted with trimethylphosphine (PMe3) to give mer,trans-Re(N-C6H3-i-Pr2)(PMe3)2Cl3, 5, which was converted to mer-Re(N-C6H3-i-Pr2)(PMe)(OPMe3)Cl3, 6, on exposure to air. Crystallographic data for 2: monoclinic space group P21/n, a = 8.870(2) Å, b = 14.393(3) Å, c = 17.114(4) Å, β = 101.43(2)°, Z = 4, R(wR2) = 0.0521(0.1293). Crystallographic data for 5: orthorhombic space group P212121, a = 11.307(l) Å, b = 11.802(l) Å, c = 19.193(2) Å, Z = 4, R(wR2) = 0.0250(0.0593). Crystallographic data for 6: orthorhombic space group P212121, a = 14.036(4) Å, b = 16.486(5) Å, c = 11.397(3) Å, Z = 4, R(wR2) = 0.0261(0.0630).

• 연구논문집
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• s.34
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• pp.139-146
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• 2004

In this study, effect of temperature and time on melt-out of 25wt% Al-alloyed ductile iron has been investigated. The oxidation tests were carried out in a tube furnace at $800^\circC$, $930^\circC$, and $1000^\circC$ for lh, 5h, 10h, 50h. The microstructure, microhardness, and $Al_2O_3$ layer of oxidation-treated 25wt% Al-alloyed ductile iron samples (10 x 10 x 10 mm) were investigated. Phase identification was performed by X-ray diffraction(XRD) and EDS. The oxidation-treated 25wt% Al-alloyed ductile iron samples at $930^\circC$ for lh, 5h, 10h and KS GCD 500 were used for melt-out test in an Al alloy melt. The melt-out test results showed that oxidation tested sample at $930^\circC$ for 5h which on the whole forms $2-3\mum$ $Al_2O_3$ layer showed lowest melt-out depth. It was observed showed that appropriate Al203 layer can affect melt-out behaviors.

• Journal of IKEEE
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• v.25 no.1
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• pp.1-9
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• 2021

In this paper, a 4H-SiC UMOSFET was studied which is suitable for high voltage and high current applications. In general, SiO2 is a material most commonly used as a gate dielectric material in SiC MOSFETs. However, since the dielectric constant value is 2.5 times lower than 4H-SiC, it suffers a high electric field and has poor characteristics in the SiO2/SiC junction. Therefore, the static characteristics of a device with high-k material as a gate dielectric and a device with SiO2 were compared using TCAD simulation. The results show BV decreased, VTH decreased, gm increased, and Ron decreased. Especially when the temperature is 300K, the Ron of Al2O3 and HfO2 decreases by 66.29% and 69.49%. and at 600K, Ron decreases by 39.71% and 49.88%, respectively. Thus, Al2O3 and HfO2 are suitable as gate dielectric materials for high voltage SiC MOSFET.

• Herbal Formula Science
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• v.28 no.3
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• pp.255-269
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• 2020

Objectives : Hemistepta lyrata Bunge (Bunge) is a wild herb that has been used for managing fever and wound in Korean Traditional Medicine. The present study explored the effects of H. lyrata extract on liver X receptor (LXR) α-dependent lipogenic genes in hepatocyte-derived cells. Methods : After HepG2 cells or Huh7 cells were pre-treated with 1-10 ㎍/mL of H. lyrata extract or its fractionated extract for 0.5 h, the cells were subsequently exposed to LXR ligand for 6-24 h. Cell viability, LXR response element (LXRE)-driven luciferase activity, sterol regulatory element binding protein-response element (SREBP-RE)-driven luciferase activity, SREBP-1c expression, and mRNA levels of LXRα and its-dependent target genes were determined. In addition, LC-MS/MS analysis was conducted to explore major compounds in H. lyrata-chloroform fractionated extract #4 (HL-CF4). Results : Of various H. lyrata extracts tested, chloroform extract and its fractionated extract #4, HL-CF4, significantly decreased T0901317-mediated SREBP-1c expression. In addition, HL-CF4 significantly reduced LXRE atransactivation and LXRα mRNA expression without any cytotoxicity. Moreover, HL-CF4 prevented the SREBP-RE-driven luciferase activity and mRNA levels of fatty acid synthase and stearoyl-CoA desaturase-1 induced by T0901317. Results from LC-MS/MS analysis at positive/negative mode indicated that HL-CF4 contained several compounds showing m/z 197.1176 (C₁₁H₁₇O₃), 693.2913/227.1069 (C₃₈H₄₅O₁₂/C₁₅H₁₅O₂), 203.1797 (C₁₅H₂₃), 181.1225 (C₁₁H₁₇O₂), 591.2957 (C₃₅H₄₃O₈), 379.1040 (C₁₈H₁₉O₉), 409.1509 (C₂₀H₂₅O₉), 309.1348 (C₁₆H₂₁O₆), 391.1404 (C₂₀H₂₃O₈), and 669.2924/389.1248 (C₃₆H₄₅O₁₂/C₂₀H₂₁O₈). Conclusion : Based on its inhibition of the LXRα-dependent signaling pathway, H. lyrata chloroform extract and HL-CF4 have prophylactic potentials for managing non-alcoholic fatty liver.

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.30-30
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• 2002

Heating [Cp＊Rh(η²-NO₃)(OTf) (1) and PhC≡CPh in EtOH for 3 h gave a η⁴-cyclobutadienerhodium complex, [Cp＊Rh(η⁴-C₄Ph₄)] (2). Complex 1 reacted with HC=CPh in acetone at room temperature for 3 h to give a (η⁴-cyclobutadiene)-rhodium complex, [Cp＊Rh(η⁴-C₄HPhC=CPh)] (3). Whereas, the reactions of 1 with HC=CCH₂Cl in acetone at room temperature for 3 h gave the triply halide-bridged dinuclear rhodium complex, [Cp＊Rh(μ₂-Cl)₃RhCp＊](OTf) (4). Complexes 2-4 have been structurally characterized by X-ray diffraction.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1525-1528
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• 2005

The synthesis and characterization of ${K_3[Ru(C_2O_4)3]{\cdot}4H_2O\;(C_2O_4}^{2-}$ = oxalato anoin) complex are described, and its redox properties (in buffer solution of pH = 12) have been investigated. This complex is used for in situ generation of oxoruthenates complexes which have been characterized by electronic spectroscopy. Reaction of ${K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ with excess ${S_2O_8}^{2-}$ in molar KOH generates trans-${[RuO_3(OH)_2]^{2-}/S_2O_8}^{2-}$ reagent while with excess ${BrO_3}^-$ in molar $Na_2CO_3$ generates ${[RuO_4]^-/BrO_3}^-$ reagent. Avoiding the direct use of [$RuO_4$] the organic-soluble $(n-Pr_4N)^+[RuO_4]^-$, (TPAP) has been isolated by reaction of $K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ with excess ${BrO_3}^-$ in molar carbonate and n-$Pr_4$NOH. In a mixture of $H_2O/CCl_4$ ruthenium tetraoxide can be generated by reaction of $K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ with excess ${IO_4}^-$. The catalytic activities of oxoruthenates that have been made from $K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ towards the oxidation of benzyl alcohol, piperonyl alcohol, benzaldehyde and benzyl amine at room temperature have been studied.