• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2001.11a
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• pp.20-23
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• 2001

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.198.2-198
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• 2003

• Elastomers and Composites
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• v.45 no.1
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• pp.17-24
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• 2010

Herein, the effect of the dispersion uniformity of the multi-wall carbon nanotube (MWCNT) on the thermal and electrical conductivity of polystyrene (PS)/MWCNT composite was investigated. The PS/MWCNT composites were prepared by solution mixing from dispersions of various MWCNTs in PS/tetrahydrofuran (THF) solution. Three types of MWCNTs were used; pristine MWCNT, hydroxyl functionalized MWCNT, which was functionalized with $KMnO_4$ in the presence of a phase transfer catalyst at room temperature, and pristine MWCNT with BYK-9077 as a dispersant. It was found that the stable dispersion state of MWCNT in PS/THF solutions significantly improved the thermal and electrical conductivity of the ultimate composites. It is noted that the thermal and electrical conductivity of PS/3 wt% pristine MWCNT composite with BYK-9077 were about 9.4 and 30~50% higher than those of PS/3 wt% pristine MWCNT composite, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.711-718
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• 2017

Silver nanoparticles were attached by chemical reduction after synthesizing a porous PVK-CTA complex. The PVK-CTA complex was synthesized by polymerizing N-vinylcarbazole in a CTA-chloroform solution using iron(III) chloride as an oxidizing agent and a honeycomb-pattern with uniformly formed macropores was formed by applying steam to the complex surface soaked with a volatile solvent under humid conditions. Using TTF as a reducing agent and PVP as a dispersant, silver nanoparticles were attached on the Honeycomb-pattern complex surface through chemical reduction. The formation of the complex was confirmed by FT-IR and UV-Vis spectrometry, and the degree of thermal decomposition of the complexes was analyzed after N-vinylcarbazole was polymerized by varying its concentration. The uniformity of the pores on the composite surface and the dispersibility of the attached silver nanoparticles were investigated by SEM. The dispersibility of the silver nanoparticles was also analyzed by varying the concentrations of reducing agent and dispersant and precursor.

• Membrane Journal
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• v.25 no.1
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• pp.15-26
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• 2015

In this study, porous metal (O.D. = 10 mm, length = 10 mm, 316 L SUS, Mott Corp.) and ${\alpha}$-alumina tube (O.D. = 10 mm, length = 50 mm, Pall, German) support was modified with suspension sols, which were consisted of $3{\sim}4{\mu}m$ and 150 nm size of ${\alpha}$-alumina particle in the water or silica-zirconia colloidal sol. The porous support was fabricated by dip coating method for 5 seconds with suspension of alumina particles. After drying at $100^{\circ}C$ for 1 h, it was calcined at $550^{\circ}C$ for 30 min. It was repeated several times in order to decrease big pore on support. The surface roughness and largest pore size on the porous support was decreased by increasing coating times with $3{\sim}4{\mu}m$ size of ${\alpha}$-alumina particle and alumina coating with 150 nm size of ${\alpha}$-alumina particle served as further smoothening the surface and decreasing the pore size of the substrate. And the silica-zirconia membranes were successfully prepared on the modified porous metal and ${\alpha}$-alumina supports, and showed hydrogen permeance in the range of $1.8-8.4{\times}10^{-4}mol{\cdot}m^{-2}{\cdot}s^{-1}{\cdot}Pa^{-1}$ and $3.3-5.0{\times}10^{-5}mol{\cdot}m^{-2}{\cdot}s^{-1}{\cdot}Pa^{-1}$, respectively.

• Journal of the Korean Chemical Society
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• v.48 no.6
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• pp.590-598
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• 2004

The preconcentration and determination of trace Cu(II) and Pb(II) on calcium alginate beads in aqueous solution were studied. A calcium alginate beads were prepared by adding an alginic acid to sample solution contained Ca(II). Some following conditions were optimized: the pH of sample solution, amount of alginic acid, and stirring time for effective adsorption; the type and concentration of acid, and sonication time in an ultrasonic vibrator for the perfect de-sorption. A sample solution was prepared with Cu(II) and Pb(II) in DI water. And Ca(II) and ethanol was added into the sample solution. The pH of the final sample solution was controlled with buffer solution. The alginic acid were dispersed in the sample solution by a magnetic stirrer. This mixture was stored in room temperature for 30 min to form a calcium alginate. After the beads were filtered and washed on a membrane filter, the analytes were redissolved from the beads by an ultrasonic vibration of 10 minutes in 1.0M $HNO_3$ solution. The effect of diverse ions on the adsorption of analytes were studied. This procedure was applied for the analysis of two real samples. The recoveries in spiked samples were $90.4{\sim}104.3%$ for analytes.

• Journal of Energy Engineering
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• v.4 no.3
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• pp.309-314
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• 1995

촉매의 담지순서 카본블랙의 종류 및 전처리 방법 등을 달리하여 연료전지 전극용 백금/카본 분말을 제조하고 이것의 백금 유실율, 백금 분산율 및 촉매 활성을 살표보았으며, 이를 사용하여 제조한 전극의 단위전지 성능을 상용전극과 비교하였다. 실험결과 카본블랙에 백금용액을 먼저 혼합한 후 환원시키는 전극제조 방법은 기존의 콜로이달법 보다 백금의 유실율이 적고 분산율이 높았다. 그리고 산/염기를 이용한 카본블랙의 전처리는 표면적은 줄어들지만 촉매활성을 증가시켰으며, 전극촉매의 최적 활성화 온도는 30$0^{\circ}C$이었다.

• Textile Coloration and Finishing
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• v.8 no.4
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• pp.59-68
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• 1996

섬유산업에 초음파의 이용은 극히 새로운 것이 아니며, 초음파를 이용하여 시간단축과 공정개선 등에 관한 많은 문헌들도 있다. 게다가 세정과 기계분야, 안정된 분산용액의 제조에 두드러지게 활용되고 있는 기술이며, 다른 새로운 분야로도 연구확대되고 있다. 주로 세정조에 구성되어 있는 초음파발생자치는 세정효율을 높이기 때문에 응용확대가 기대된다. 특별한 장치가 필요없기 때문에 음화학반응에서 관심이 모아지고 있다. 초음파는 이제 광범위한 습식공정에 영향을 미치는 기술로 이해되고 있다. 이 자료는 이미 연구된 결과를 재조명하고 초음파를 이용하므로서 얻을 수 있는 이점에 대해서 어떤 것이 있는지에 대해 살펴보고자 한다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.67-67
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• 2011

퍼멀로이의 내식성, 기계적 성질 등을 증가시키기 위해 복합도금을 실시하였다. 실리카 나노분말의 분산특성을 Zeta potential을 이용하여 측정하였으며 알칼리 도금액에서 퍼멀로이-실리카 복합도금을 실시하였다. 실리카 나노분말의 응집을 최소로 하기 위하여 전극의 RPM 변화, 첨가제와 초음파의 복합처리에 따른 변화, 전류 밀도 변화를 살펴보았다.

• Polymer(Korea)
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• v.34 no.2
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• pp.144-149
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• 2010

Ag/polystyrene(PS) nanocomposites were prepared by in situ reduction of silver 2-ethylhexylcarbamate (Ag-CB) complex and follwing radical polymerization only by heating at 110 $^{\circ}C$. In contrast to this conventional heating method, the microwave irradiation afforded well-dispersed silver nanoparticles(NPs) in styrene monomer without polymerization. The synthesis of Ag NPs proceeded uniformly throughout the reaction vessel only under microwave irradiation, completing the reaction simultaneously in the whole reaction solution. Successive polymerization of the monomer containing the resultant NPs has successfully produced a hybrid of the silver NPs dispersed in PS matrix. Ag/PS (0.1/100) nanocomposites were prepared successfully by melt-mixing process using Ag/PS(4.0/100) as a master-batch. UV-VIS spectroscopy, TEM, and X-ray diffraction techniques were used to investigate the process of formation of Ag/PS nanocomposites.