• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1613-1619
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• 2011

A hybrid thermosetting maleimido epoxy compound 4-(N-maleimidophenyl) glycidylether (N-MPGE) containing Co(II), Ni(II) and Cu(II) ions was prepared by curing N-MPGE and tetradentate Schiff base Co(II), Ni(II) and Cu(II) complexes. The curing polymerization reaction of N-MPGE with metal complexes as curing agents was studied. The cured samples were studied for thermal stability, chemical (acid/alkali/solvent) and water absorption resistance and homogeneity of the cured systems. The tetradentate Schiff base, 3-[(Z)-2-piperazin-1-yl-ethylimino]-1,3-dihydro indol-2-one was synthesized by the condensation of Isatin (Indole-2, 3-dione) with 1-(2-aminoethyl)piperazine (AEP). Its complexes with Co(II), Ni(II) and Cu(II) have been synthesized and characterized by microanalysis, conductivity, Uv-Visible, FT-IR, TGA and magnetic susceptibility measurements. The spectral data revealed that the ligand acts as a neutral tetradentate Schiff base and coordinating through the azomethine nitrogen, two piperazine nitrogen atoms and carbonyl oxygen.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.1
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• pp.1-7
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• 2020

The synthesis and catalytic activities over vanadium carbides were examined for ammonia decomposition reaction to produce the hydrogen. In particular, the comparison of vanadium nitrides were made on the ammonia decomposition reaction. The experimental data exhibited that BET surface areas ranged from 5.2 ㎡/g to 25.6 ㎡/g and oxygen uptake values varied from 3.8 μmol/g to 31.3 μmol/g. It is general that vanadium carbides (VC) were observed to be superior to vanadium nitrides for ammonia decomposition reaction. The primary reason for these differences were thought to be related to the extent of electronegativity between these materials. Most of vanadium carbide crystallites were exceeded by Pt/C crystallite. We assumed that the activities for vanadium carbide crystallites (VC) were comparable to or even higher than that determined for the Pt/C crystallite.

• Carbon letters
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• v.2 no.3_4
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• pp.176-181
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• 2001

A series of activated carbons were prepared from coconut shells and coal-tar pitch binder by physical activation with steam in this study. The effect of variable processes such as activation temperature, activation time and ratio of mixing was investigated for optimizing those preparation parameters. The activation processes were carried out continuously. The nitrogen adsorption isotherms at 77 K on pellet-shaped activated carbons show the same trend of Type I by IUPAC classification. The average pore sizes were about 19-21${\AA}$. The specific surface areas ($S_{BET}$) of pellet typed ACs increased with increasing the activation temperature and time. Specific surface area of AC treated for 90 min at temperature $900^{\circ}C$ was 1082 $m^2/g$. The methylene blue numbers continuously increased with increasing the activation temperature and time. On the other hand, iodine numbers highly increased till activation time of 60 min, but the rate of increase of iodine numbers decreased after that time. This indicates that new micropores were created and the existing micropores turned into mesopores and macropores because of increased reactivity of carbon surface and $H_2O$.

• Macromolecular Research
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• v.17 no.12
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• pp.1021-1024
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• 2009

We successfully prepared high-flow polycarbonate (PC) by blending commercial PC with a low molecular weight PC oligomer. The oligomer was synthesized by the addition of a large quantity of mono functional phenol groups, and the chain end group was reacted with p-tertiary butyl phenol (PTBP) to block the reactivity. The viscosity average molecular weight ($M_v$) for the oligomer was about 4,000-5,000 g/mol, compared to ~19,000 g/mol for the PC blend obtained by blending 10 wt% of the prepared oligomer with the commercial grade PC ($M_v$ of 21,000 g/mol). The blended PC had a melt flow index of 45, which is 2.5 times higher, and a processing temperature that was $20^{\circ}C$ lower, than that of commercial grade PC having a similar $M_v$.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.1
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• pp.90-96
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• 2018

Reaction characteristics and kinetics of a oxygen carrier (OCN717-R1SU) for chemical looping combustion (CLC) have been investigated using TGA by changing gas concentration (10-30 vol.% $CH_4$) and reaction temperature ($825-900^{\circ}C$). Reaction rate of OCN717-R1SU increased as temperature increased and it was found that reaction is delayed at the initial reaction regime. Johnson-Mehl-Avrami (JMA) model was adopted to explain the reaction phenomenon. The activation energy (E) determined by JMA model in reduction reaction of OCN717-R1SU is $151.7{\pm}2.03kJ/mol$ and pre-exponential factor and JMA exponent were also obtained. The parameters calculated in this study will be applied in design of the reactor and operation conditions for CLC process.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.1979-1984
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• 2014

We have developed an efficient method to generate highly active Pd and PdO nanoparticles (NPs) dispersed on graphene and graphene oxide (GO) by an impregnation method combined with thermal treatments in $H_2$ and $O_2$ gas flows, respectively. The Pd NPs supported on graphene (Pd/G) and the PdO NPs supported on GO (PdO/GO) demonstrated excellent carbon-carbon cross-coupling reactions under a solvent-free, environmentally-friendly condition. The morphological and chemical structures of PdO/GO and Pd/G were fully characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). We found that the remarkable reactivity of the Pd/G and PdO/GO catalysts toward the cross-coupling reaction is attributed to the high degree of dispersion of the Pd and PdO NPs while the oxidative states of Pd and the oxygen functionalities of graphene oxide are not critical for their catalytic performance.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.131-135
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• 2005

Gallium nitride (GaN) powders and nanowires were prepared by using tris(N,N-dimethyldithiocarbamato)gallium(III) (Ga(DmDTC)$_3$) and tris(N,N-diethyldithiocarbamato)gallium(III) (Ga(DeDTC)$_3$) as new precursors. The GaN powders were obtained by reaction of the complexes with ammonia in the temperature ranging from 500 to 1100 ${^{\circ}C}$. The process of conversion of the complexes to GaN was monitored by their weight loss, XRD, and $^{71}$Ga magic-angle spinning (MAS) NMR spectroscopy. Most likely the complexes decompose to $\gamma$ -Ga$_2$S$_3$ and then turn into GaN via amorphous gallium thionitrides (GaS$_x$N$_y$). The reactivity of Ga(DmDTC)$_3$ with ammonia was a little higher than that of Ga(DeDTC)$_3$. Room-temperature photoluminescence spectra of asprepared GaN powders exhibited the band-edge emission of GaN at 363 nm. GaN nanowires were obtained by nitridation of as-ground $\gamma$ -Ga$_2$S$_3$ powders to GaN powders, followed by sublimation without using templates or catalysts.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.630-635
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• 2007

New chiral Co-salen complexes with one $C_3-^tBu$ group in the structure have been synthesized and applied as a chiral catalyst. A dimeric chiral salen having aluminum group metal salts such as $AlCl_3$ displayed very high catalytic reactivity and enantioselectivity for the asymmetric ring opening of epoxides to synthesize optically pure ${\alpha}$-aryloxy alcohols via phenolic kinetic resolution. The salen complexes immobilized on the inorganic support were also used as effective catalysts in that reaction. The identity of metal salts in the new chiral salen complex has proved to be important in the enantioselective reactions.

• Journal of Information Management
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• v.28 no.2
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• pp.1-19
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• 1997

A late-comer in the marine affairs, development of ways for efficient access and utilization of information on marine environmental conservation and pollution prevention is important. The properties and removal methods of toxic chemicals have been entered into the database for 1,000 substances. The database of toxic chemicals for pollution and spills has also been fortified for the following terms: general characteristics, health hazard and response, fire hazard and response, chemical reactivity, physico-chemical properties, and other properties. The information and data running in this database are easily accessible via Internet and Korean telecommunications companies; it is also available KRISTAL databases.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1396-1400
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• 2007

In this study, poly(iso-butyl methacrylate-co-ethylene glycol dimethacrylate) [poly(iso-BMA-co-EGDMA)] microgel was prepared and used as a face powder additive. The spreading, adhesiveness, and skin reactivity of poly(iso-BMA-co-EGDMA) microgel-containing face powder II were investigated and compared with the same properties of commercially available Silica bead 700-containing face powder I. In the results, the particle size of the poly(iso-BMA-co-EGDMA) microgel was significantly swelled as a result of sebum absorption. Face powder II showed a lower primary irritation index and a higher adhesiveness than did face powder I. Face powder I showed a low sebum absorption ratio and a relatively high rate of sebum absorption, whereas face powder II, contrastingly, exhibited a high sebum absorption ratio and a low rate of sebum absorption, which properties would reduce the phenomena of facial strain and sliminess. These results indicate that poly(iso- BMA-co-EGDMA) microgel has outstanding sebum absorption characteristic and adhesiveness, and thus that it is a good candidate for use as a face powder additive.