• Bulletin of the Korean Chemical Society
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• v.35 no.9
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• pp.2726-2732
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• 2014

The promoting effect of rhodium on the structure and activity of the supported Cu-Co based catalysts for CO hydrogenation was investigated in detail. The samples were characterized by DRIFTS, $N_2$-adsorption, XRD, $H_2$-TPR, $H_2$-TPD and XPS. The results indicated that the introduction of rhodium to Cu-Co catalysts resulted in modification of metal dispersion, reducibility and crystal structure. DRIFTS results of CO hydrogenation at reaction condition (P=2 MPa, $T=260^{\circ}C$) indicated the addition of 1 wt % rhodium improved hydrogenation ability of Cu-Co catalysts. The ethanol selectivity and CO conversion were both improved by 1 wt % Rh promoted Cu-Co based catalysts. The alcohol distribution over un-promoted and rhodium promoted Cu-Co based catalysts obeys A-S-F rule and higher chain growth probability was got on rhodium promoted catalyst.

• Journal of Powder Materials
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• v.22 no.5
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• pp.356-361
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• 2015

Fe-30 wt% TiC composite powders are fabricated by in situ reaction synthesis after planetary ball milling of (Fe, $TiH_2$, Carbon) powder mixture. Two sintering methods of a pressureless sintering and a spark-plasma sintering are tested to densify the Fe-30 wt% TiC composite powder compacts. Pressureless sintering is performed at 1100, 1200 and $1300^{\circ}C$ for 1-3 hours in a tube furnace under flowing argon gas atmosphere. Spark-plasma sintering is carried out under the following condition: sintering temperature of $1050^{\circ}C$, soaking time of 10 min, sintering pressure of 50 MPa, heating rate of $50^{\circ}C/min$, and in a vacuum of 0.1 Pa. The curves of shrinkage and its derivative (shrinkage rate) are obtained from the data stored automatically during sintering process. The densification behaviors are investigated from the observation of fracture surface and cross-section of the sintered compacts. The pressureless-sintered powder compacts are not densified even after sintering at $1300^{\circ}C$ for 3 h, which shows a relative denstiy of 66.9%. Spark-plasma sintering at $1050^{\circ}C$ for 10 min exhibits nearly full densification of 99.6% relative density under the sintering pressure of 50 MPa.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1832-1836
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• 2014

A deep understanding of the metallic silver catalysts formation process on oxide support and the formation mechanism is of great scientific and practical meaning for exploring better catalyst preparing procedures. Herein the thermal decomposition process of supported silver catalyst with silver oxalate as the silver precursor in the presence of ethylenediamine and ethanolamine is carefully investigated by employing a variety of characterization techniques including thermal analysis, in situ diffuse reflectance infrared Fourier transform spectroscopy, scanning electron microscopy, and X-ray diffraction. The formation mechanism of supported silver particles was revealed. Results showed that formation of metallic silver begins at about $100^{\circ}C$ and activation process is essentially complete below $145^{\circ}C$. Formation of silver was accompanied by decomposition of oxalate group and removal of organic amines. Catalytic performance tests using the epoxidation of ethylene as a probe reaction showed that rapid activation (for 5 minutes) at a relatively low temperature ($170^{\circ}C$) afforded materials with optimum catalytic performance, since higher activation temperatures and/or longer activation times resulted in sintering of the silver particles.

• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.27-32
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• 2011

Management of gas safety is becoming important with increasing use of gas facilities. U-safety system is being promoted as part of national management of gas, and thus real-time and in-situ gas sensor should be developed. Detection method for When the gas sensor is installed in gas conduit, explosion may be likely, because hydrocarbon gases is usually used the difference of thermal resistance between reference and working electrode. Therefore, it is required to detect the hydrocarbons, such as $CH_4$ and CO, at room temperature via electrochemically catalytic reaction. In this study, Pt nanoparticle was doped on the porous gold powder by electrolytic plating method, and then it was used as catalytic electrode for CO oxidation. For Pt/PAu electrode, approximately 21% of CO conversion was obtained. It is noted that Pt/PAu electrode could be used to react the oxidation of hydrocarbon gases at room temperature via applying of external voltage.

• Macromolecular Research
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• v.16 no.5
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• pp.441-445
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• 2008

A series of aluminum complexes supported by $\beta$-ketoamino, ligand-bearing, 3-position substituents $LAlEt_2$ ($L=CH_3C(O)C(Cl)=C(CH_3)NAr\;(L_1)$, $L=CH_3C(O)C(H)=C(CH_3)NAr\;(L_2)$, $L=CH_3C(O)C(Ph)=C(CH_3)NAr\;(L_3)$, and $L=CH_3C(O)C(Me)=C(CH_3)NAr\;(L_4)$, $Ar=2,6-^iPr_2C6H_3$) were synthesized in situ and employed in the ring-opening polymerization (ROP) of $\varepsilon$-caprolactone ($\varepsilon$-CL) and cyclohexene oxide (CHO). The 3-position substituents on the $\beta$-ketoamino ligand backbone of the aluminum complexes influenced the catalyst activity remarkably for both ROP of $\varepsilon$-CL and CHO. Aluminum $\beta$-ketoamino complexes displayed different catalytic behavior in ROP of $\varepsilon$-CL and CHO. The order of the catalytic activity of $LAlEt_2$ was $L_1AlEt_2$>$L_2AlEt_2$>$L_3AlEt_2$>$L_4AlEt_2$ for ROP of $\varepsilon$-CL, being opposite to the electron-donating ability of the 3-position substituents on the $\beta$-ketoamino ligand, while the order of the catalytic activity for ROP of CHO was $L_1AlEt_2$>$L_3AlEt_2$>$L_4AlEt_2$>$L_2AlEt_2$. The effects of reaction temperature and time on the ROP were also investigated for both $\varepsilon$-CL and CHO.

• Resources Recycling
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• v.29 no.1
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• pp.25-34
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• 2020

Electrochemical Quartz Crystal microbalance is a tool that is capable of measuring nanogram-scale mass change on electrode surface. When applying alternating voltage to the quartz crystal with metal electrode formed on both sides, a resonant frequency by inverse piezoelectric effect depends on its thickness. The resonant frequency changes sensitively by mass change on its electrode surface; frequency increase with metal dissolution and decrease with metal deposition on the electrode surface. The relationship between resonant frequency and mass change is shown by Sauerbrey equation so that the mass change during metal dissolution can be measured in real time. Especially, it is effective in the case of reaction mechanism and rate studies accompanied by precipitation, volatilization, compound formation, etc. resulting in difficulties on ex-situ AA or ICP analysis. However, it should be carefully considered during EQCM experiments that temperature, viscosity, and hydraulic pressure of solution, and stress and surface roughness can affect on the resonant frequency. Application of EQCM was shown as a case study on leaching of platinum using aqueous chlorine for obtaining activation energy. A platinum electrode of quartz crystal oscillator with 1000 Å thickness exposed to solution was used as leaching sample. Electrogenerated chlorine as oxidant was purged and its concentration was controlled in hydrochloric acid solution. From the experimental results, platinum dissolution by chlorine is chemical reaction control with activation energy of 83.5 kJ/mol.

• Journal of Animal Science and Technology
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• v.46 no.4
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• pp.555-562
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• 2004

본 연구는 목저은 다음과 같다: 1) 돼지에서 150-kDa temary insulin-like growth faetor(IGF)complex의 한 구성 요소인 acid-labile subunit(ALS) 유전자 intron의 존재 확인. cloning 및 돼지 ALS(porcine ALS; pALS) complementary DNA(cDNA)의 3' 비해독(untranslated) 부위(3' UT) 증폭. cloning, 2) intron-spanning primer pair를 이용한 reverse transcription-polymerase chain reaction(RT-PCR) 방법에 의한 돼지 조직에서의 ALS 유전자 발현 분포 확인 및 3) 돼지 hepatocyte에서의 ALS 유전자 발현 여부 확인. 돼지 genomic DNA를 template로 하여 PCR 방법으로 예상된는 intron 부위를 증폭하고 plasmid vector에 삽입하여 염기서열을 결정한 결과 타 종의 ALS 유전자에서와 같은 위치에 1,371-base pair(bp)의 pALS intron이 존재함을 확인하였다. 역시 본 연구에서 간에서 추출한 RNA를 주형으로 시작하여 3' rapid amplification of cDNA end(3' RACE) 방법으로 147-bp의 3'UT를 합성하고 그 염기성열을 결정하였다. RT-PCR 결과 간은 물론 조사된 모든 돼지의 내장기관(신장, 폐, 비장)과 자성 생식기관(난소, 난관, 자궁) 및 골격근육에서 ALS 유전자가 발현됨이 밝혀졌다. 또한 돼지 간 조직에 대한 in-situ hybridization 결과 hepatocyte에서 ALS 유전자가 발현됨이 확인되었다. 이상의 결과는 ALS가 혈중 IGF의 저정/조절체로서의 주기능 외에 모세혈관 밖에서도 미지의 기능이 있을 기능성을 시사한다.

• Journal of the Korean Geotechnical Society
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• v.15 no.3
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• pp.151-160
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• 1999

The settlement limit concept is generally adopted as design criteria of rock-socketed pile foundations, therefore, the load-displacement$(\sigma-\sigma)$ behavior of the rock-socketed piles should be well understood at the design stage, which, however, is hard to achieve due to its complexity. To help this out, field pile load tests are executed on cast-in-situ concrete piles, first, to figure out the $\sigma$-$\delta$ behavior of rock-socketed piles. Next, the $\sigma-\sigma$ relations of the piles are simulated numerically using commercial package program(ELAC) varying a couple of input data which are sensitive in shaping the $\sigma$-$\delta$ curves. Finally, the relation between the best input data for the numerical simulations and the geotechnical field data are cultivated to generalize the numerical simulation procedures, which enables geotechnical engineers to predict the $\sigma$-$\delta$ behavior at the design stage, if appropriate geotechnical field data are provided.

• Bulletin of the Korean Chemical Society
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• v.17 no.7
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• pp.637-642
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• 1996

Preparation and properties of potential CVD (Chemical Vapor Deposition) precursors for the TiO2, a major component of the perovskite materials such as PT, PLT, PZT, and PLZT were investigated. Reactions between β-diketones and TiMe3, formed in situ failed to produce stable Ti(β-diketonate)3 complexes but a stable purple solid, characterized as (OTi(BPP)2)2 (BPP=1,3-biphenyl-1,3-propanedione) was obtained when BPP was used. Several new Ti(Oi-Pr)2(β-diketonate)2 complexes with aromatic or ring substituents were synthesized by the substitution reaction of Ti(OiPr)4by β-diketones and characterized with 1H NMR, IR, ICP, and TGA. Solid complexes such as Ti(Oi-Pr)2(BAC)2 (BAC=1.-phenyl-2,4-pentanedione), Ti(Oi-Pr)2(BPP)2, Ti(Oi-Pr)2(1-HAN)2 (1-HAN=2-hydroxy-1-acetonaphthone), Ti(Oi-Pr)2(2-HAN)2 (2-HAN=1-hydroxy-2-acetonaphthone), Ti(Oi-Pr)2(ACCP)2 (ACCP=2-acetylcyclopentanone), and Ti(Oi-Pr)2(HBP)2 (HBP=2-hydroxybenzophenone) were found to be stable toward moisture and air. Ti(Oi-Pr)2(ACCP)2 and Ti(Oi-Pr)2(HBP)2 were proved to have lower melting points and higher decomposition temperatures. However, these complexes are thermally stable and pyrolysis under an inert atmosphere resulted in incomplete decomposition. Ti(Oi-Pr)2(DPM)2 (DPM=dipivaloylmethane) and Ti(Oi-Pr)2(HFAA)2 (HFAA=hexafluoroacetylacetone) were sublimed substantially during the thermal decomposition. Pyrolysis mechanism of these complexes are dependent on type of β-diketone but removal of Oi-Pr ligands occurs before the decomposition of β-diketonate ligands.

• Journal of the Korean Electrochemical Society
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• v.15 no.3
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• pp.154-159
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• 2012

Structural volume change occurring on the Si-based anode battery materials during alloying/dealloying with lithium is noticed to be a major drawback responsible for a limited cycle life. Silicon monoxide has been reported to show relatively improved cycling performance compared to Si-containing materials for rechargeable lithium batteries, due to the structural buffering role of in-situ formed $Li_2O$ and lithium silicate during the reaction of silicon monoxide and lithium. Here we report improved cycling ability of interfacially stabilized Si-$SiO_2$-graphite composite anode using silane-based electrolyte additive for rechargeable lithium batteries, which includes low cost silicon dioxide for structural stabilization and graphite for enhanced conductivity.