• Korean Journal of Materials Research
• /
• v.5 no.3
• /
• pp.324-332
• /
• 1995

전자빔 증착법을 사용하여 Ti과 Co를 Si(100) 단결정, 다결정 Si 및 Si$O_{2}$기판에 증착한 후 90$0^{\circ}C$에서 20초 급속 열처리하여, Co/Ti 이중박막으로부터의 실리사이드화 반응을 조사하였다. 단결정 시편의 경우 Ti의 두께를 5~6mm로 최소화함으로서 두께가 균일하고 기판과의 계면이 평탄하며 비저항이 낮고 열적 안정성이 높은 Co$Si_{2}$ 에피박막을 형성할 수 있었다. 그러나 다결정 시편에는 두께와 계면이 불균일하고 열적으로도 불안정한 다결정의 Co$Si_{2}$와 그 위에 두개의 Co-Ti-Si혼합층이 형성되었다. 한편 Si$O_{2}$ 우에 증착된 Co/Ti은 열처리를 하여도 확산하지 않고 그대로 남아 있어서, Co/Ti 이중박막의 Si$O_{2}$와의 반응성이 미약함을 보여 주었다.

• Korean Journal of Food Science and Technology
• /
• v.44 no.5
• /
• pp.600-606
• /
• 2012

A Bacillus sp. that produces fibrinolytic enzyme was isolated from Cheonggukjang, a traditional Korean soybean-fermented food. According to 16S rRNA gene base sequencing, the bacillus was identified as a variety of Bacillus subtilis, and named Bacillus subtilis IDCC 9204. Fibrinolytic enzyme NK-IL9204 was stable up to $60^{\circ}C$ and within pH range of 5-10. Purified NK-IL9204 was detected through fibrin zymography. The molecular weight and isoelectric point of the enzyme were estimated to be 27.7 kDa and 6.7 by SDS-PAGE and 2D electrophoresis, respectively. Its amino acid sequence was similar to that of nattokinase (identities 99.5%) and different from that of nattokinase BPN (identities 86.4%). The plasma fibrinolytic activity of NK-IL9204 was measured by euglobulin clot lysis times (ECLT). The NK-IL9204 was orally administered to SD rats for 3 weeks (1,000 FU/rat/day). The ECLT was significantly shortened by supplementation of NK-IL9204.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.228-228
• /
• 2010

반도체 집적도의 비약적인 발전으로 각 박막 층간의 두께는 더욱 줄어들었고 이는 각 박막 층간의 확산에 대한 문제를 간과할 수 없게 하였다. 따라서 각 층간의 확산을 방지하기위한 확산방지막의 연구에 대한 관심도는 증가하게 되었다. 또한 본 연구에서 분석을 위하여 사용된 Nanoindenter는 박막 표면에 다이아몬드 팁을 이용하여 압입을 실시하여 이때 시표의 반응에 의한 팁의 위치(Z-축)를 in-situ로 측정하여 인가력과 팁의 위치에 대한 연속 압입곡선을 측정하게 된다. 이를 통하여 박막의 hardness와 elastin modulus를 측정하게 되고, 연속 압입곡선 분석을 통하여 박막의 표면응력 변화를 측정한다. 이 논문에서는 반도체의 기판으로 사용되는 Si 기판과 금속배선 물질인 Cu와의 확산을 효과적으로 방지하기 위한 W-C-N 확산방지막을 제시하였고, 시료 증착을 위하여 rf magnetron sputter를 사용하여 동일한 증착 조건에서 질소(N)의 비율을 다르게 하여 박막내 질소 비율에 따른 확산방지막을 제작하였다. 이후 시료의 열적 안정성 측정을 위하여 상온에서 $900^{\circ}C$ 까지 질소 분위기에서 30분간 열처리 과정을 실시하여 열적 손상을 인가하였고, 고온에서 확산방지막의 열적인 안정성을 Nanoindentation 분석을 이용하여 측정하였다. 측정 결과 박막내 질소 불포함된 박막의 경우 표면 강도는 9.01 GPa에서 194.01 GPa의 급격한 변화를 보였고, 질소가 포함된 박막은 9.41 GPa에서 43.01 GPa으로 상대적으로 적은 차이를 보였다. X-ray 분석 결과에서도 박막내 질소가 포함된 박막이 고온에서도 더 안정된 특성을 보이는 것을 확인하였다.

• Journal of the Korean Electrochemical Society
• /
• v.11 no.3
• /
• pp.141-146
• /
• 2008

Electrocatalytic activities and stabilities of Pt supported on Sb-doped $SnO_2$ (ATO) were examined for ethanol oxidation reactions. Pt colloidal particles were deposited on ATO nanoparticles (Pt/ATO) and the prepared electrocatalysts were characterized by X-ray diffraction, transmission electron microscopy (TEM), and cyclic voltammetry. Electrochemical activity of the Pt/ATO for ethanol electro-oxidation was compared to those of Pt supported on carbon (Pt/C) and commercial PtRu/C. The activitiy of the Pt/ATO was much higher than those of the Pt/C and commercial PtRu/C. The Pt/ATO exhibited much higher electrochemical stabilities than the Pt/C in 0.5M ${H_2}{SO_4}$ and in 0.5M ${H_2}{SO_4}$/1M ${C_2}{H_5}OH$. According to TEM, the growth rate of Pt particles was lower in the Pt/ATO than it was in the Pt/C. The ATO nanoparticle appears to be a promising support material that promotes electrochemical reactions and stabilizes catalyst particles in direct ethanol fuel cell.

• Polymer(Korea)
• /
• v.39 no.1
• /
• pp.180-184
• /
• 2015

PP-grafted GO was prepared by the reaction of graphene oxide (GO) containing 2-bromoisobuyryl groups and polypropylene (PP) having hydroxyl groups (PP-OH) via a "grafting-to" method. GO-Br was synthesized by the reaction of GO and 2-bromoisobutyryl bromide under a basic condition. PP-MAH was reacted with ethanolamine to produce PP-OH. The melting temperature of PP-grafted GO was shifted to the higher temperature than that of PP-OH. Also, the thermal stability of PP-grafted GO was increased as compared to PP-OH and GO. These results demonstrated that the grafted coating polymer PP was effective for enhancing the thermal stability of GO. The higher surface roughness of PP-grafted GO was resulted from the chemical attachment of PP on the surface of GO. The characterization of PP-grafted GO was conducted from Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscope (SEM).

• KSBB Journal
• /
• v.24 no.2
• /
• pp.170-176
• /
• 2009

Lectin was finally isolated on Sephadex G-100 from Korean soybean cultivars developed for soy source and investigated its some biochemical properties. Native PAGE pattern of this lectin revealed a molecular weight of 108 kDa as tetramer. The molecular weight of this lectin isolated as double protein band by SDS-PAGE was calculated to be 32 and 22 kDa from the relative mobilities compared with those of the standard proteins. Among the tested red blood cell, the isolated lectin agglutinated rabbit red blood cell treated with trypsin, but did not agglutinated human red blood cells (A, B, AB, O), rat, and untreated rabbit red blood cell. The optimal temperature and thermal stability of isolated lectin was at 20-$50^{\circ}C$ and 10-$60^{\circ}C$, respectively. This lectin was stable at 7.2, and showed complete loss in its activity below pH 6.2 and above pH 8.0.

• Elastomers and Composites
• /
• v.37 no.1
• /
• pp.31-38
• /
• 2002

Polymerization of carboxylated styrene-butadiene latex takes longer time than that of acrylic emulsion due to delocalization of radical in butadiene unit having conjugated double bond. A latex stability is the most important properties owing to use intact without separating polymer from base latex. For reducing polymerization time without decreasing any properties of latex, carbon tetra-chloride which has been used as the most popular chain transfer agent was replaced to combination of tert-dodecylmercaptane and ${\alpha}$-methylstyrene dimer. The replacement yielded reducement or 2 hr in polymerization time. In the increment step, charge amount of acrylic acid was limited to 0.3 part to restrain viscosity enhancement. Just after initial step, addition of 0.1 part acrylamide prevent polymer chain from diffusing between two region followed by giving hardness and final good adhesive force to latex particles.

• Applied Chemistry for Engineering
• /
• v.34 no.2
• /
• pp.180-185
• /
• 2023

To improve the efficiency of water electrolysis, it is essential to develop an oxygen evolution reaction (OER) electrocatalyst with high performance and long-term stability, accelerating the reaction rate of OER. In this study, a hollow metal-organic framework (MOF)-derived ruthenium-cobalt oxide catalyst was developed to synthesize an efficient OER electrocatalyst. As the synthesized catalyst increases the surface exposure of ruthenium, a low overpotential (386 mV) was observed at a current density of 10 mA/cm² with a low Tafel slope. It is expected to be able to replace noble metal catalysts by showing higher mass activity and stability than commercial RuO₂ catalysts.

• Korean Chemical Engineering Research
• /
• v.48 no.1
• /
• pp.10-15
• /
• 2010

Intensive works have been carried out to develop more efficient solid catalysts for biodiesel production from various feedstocks including refined oils and waste fats. Among many catalysts, metal oxides and ion exchange resins are the most intensively studied ones. With regard to metal oxide catalysts, major research activities have focused on the identification of the active compounds and their immobilizing methods on the supports. As metal oxide catalysts have strong thermal stability, they may be used in simultaneous transesterification and esterification of waste fats. However, ion exchange resin catalysts were mainly applied in the esterification of the free fatty acids in waste fats because of their lower thermal stability. For both solid catalysts, further works are needed to make them to be used in commercial process. Especially fast deactivation of the solid catalyst would be the most challenging problem.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.3
• /
• pp.448-452
• /
• 2006

This study was performed to evaluate the long-term teachability of the stabilized hexavalent chromium contaminated soils treated with chromium reducing agent and soluble phosphate. The study shows that $Cr^{6+}$ in the leachate was little detected and the remaining $PO_4-P$ concentration kept below 0.1 mg/L due to the formation of geochemically stable hexavalent chromium phosphate minerals from the reactions of labile soil $Cr^{6+}$ forms with the added soluble phosphate salt and chromium reducing agent. The results provide evidence for the potential use of the immobilization technique for the hexavalent chromium contaminated soil remediation in the near future.