• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.223-223
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• 2003

광통신에는 광신호의 전송과 광신호 처리에 처리 과정에서 광 손실을 수반하므로 각 요소별로 광신호 증폭이 반드시 필요하다. 또한 광통신망의 완전 광화를 위해서는 제조 공정이 간단하여 가격이 저렴하고, 높은 신뢰성과 높은 증폭 효율을 가지면서 다른 부품과의 집적화가 가능한 광도파로형 광증폭기가 요구되고 있다 그러나 실리카는 광통신 파장대인 1.55$\mu\textrm{m}$대역의 증폭이 가능한 Er 이온에 대한 용해도가 50ppm 이하로 낮아 lmol% 이상 고농도로 Er 이온을 첨가하여 높은 증폭 효율을 얻는데 한계를 가지고 있다. 따라서 본 연구에서는 Er 이온에 대하여 높은 용해 특성을 가지고 있어 고농도 Er 이온 도핑이 가능한 알루미나에 Er을 1-2 mol% 첨가하여 광발광 특성을 조사하였다. Er이 첨가된 알루미나 나노 졸은 Al(NO$_3$)$_3$ㆍ9$H_2O$와 Er(NO$_3$)$_3$.5$H_2O$가 일정 양 용해된 수용액에 NH$_4$OH를 가하여 침전물을 얻고 여과 및 수세하여 졸 입자의 함량이 약 5wt%가 되게 이온교환수와 해교제인 초산을 소량 가하여 10$0^{\circ}C$에서 약 50시간 열처리하는 방법으로 제조하였다. Er이 첨가된 알루미나 코팅막은 Er 이 첨가된 알루미나 나노 졸에 GPS(3-glycidoxypropyltriethoxysilane)를 Al에 대하여 7 mol% 가하여 스핀 코팅법으로 제조하였다. Si 기판에 코팅하고, 상온에서 90$0^{\circ}C$까지 각 1시간 열처리한 코팅막의 광 발광 특성은 Er 이온의 첨가량과 열처리로 변화된 알루미나 코팅막의 결정상과 연계하여 논의 될 것이다. X-선 회절법으로 분석한 알루미나 코팅막의 온도에 따른 결정상은 boehmite 상에서 약 50$0^{\circ}C$이후에 ${\gamma}$-Al$_2$O$_3$로 전이하고 있다.

• Analytical Science and Technology
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• v.7 no.1
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• pp.17-23
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• 1994

Through sol-gel process, inorganic/organic composite as a dye host was made. It was observed that this composite has about 90% of trnasmittance by UV/VIS spectrophotometer. The transmittance is the most important requirement to decide whether the composite could apply or not as the dye host. The transmittance was increased with decreasing HCl as a catalyst, aging time, and amount of PDMS. Also, fluorescent and transmittant charateristics of Rhodamine 6G Perchlorate that was doped into ORMOSIL were measured. The fluorescent intensity was increased and the trnasmittance was decreased with rising gelling temperature.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1561-1567
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• 2021

In this study, we have studied synthesis of zirconia-alumina composite coating materials via a low-temperature sol-gel process. The zirconia-alumina composites were prepared by coating zirconia precursor, alumina precursor, and organosilane mixture on a polyethylene terephthalate substrate through three steps: sol-gel process, low-temperature photocuring process, and heat treatment process. The structural properties and element analysis of the composites were confirmed by FT-IR and XPS. The coated composite showed a transmittance of 96% or more in the visible light region with a wavelength of 420 nm or more and pencil hardness of 9H or more. In case of the composite of the molar ratio of zirconia and alumina of 1:4, the highest nanoindentation hardness was measured with 1.212 GPa.

• Journal of the Korean Ceramic Society
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• v.29 no.5
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• pp.403-409
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• 1992

The titania membrane thickness coated on the porous alumina support by the sol-gel method was analyzed using the slipcasting model. The thickness of calcined membrane layers increased linearly from 1.3 to 3.8 ${\mu}{\textrm}{m}$ with the square root of the dipping time (4~40 min). Growth rates of the thickness of wet gels and calcined layers were well described quantitatively by the slipcasting model. Through the regression of experimental data using model equations, the permeability and the pressure drop across wet gels, and the thickness and their growth rate constants of wet gels and calcined layers could be determined. It was also known that the gellation concentration of the TiO2 sol used in this work and the porosity of wet gel layes were 25 mol/ι and 0.53, respectively.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.10a
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• pp.59-59
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• 1996

막분리에 의한 폐윤활유 재생공정을 개발하기 위한 기초 연구로써 폐윤활유 분리/재생용으로 적합한 복층(multilayer)세라믹 복합막의 제조와 합성막의 폐유 분리 효율등이 연구되었다. 결함이 없고 두께가 균일한 지르코니아 복합막 (기공크기 0.07 $\mu$m 이하)은 압출 성형법으로 제조한 튜브형 $\alpha$-알루미나 담체 (외경 7.8 mm, 두께 0.6 mm, 기공크기 0.7 $\mu$m)내부표면에 역침지 인상법(reverse dip-drawing technique)에 의하여 지르코니아 슬러리를 코팅 한 후 950$\circ$C에서 1시간 열처리하여 제조 되었다. 또한 지르코니아 복합막 위에 니타니아 졸-겔 코팅을 한 후 450$\circ$C에서 2시간 열처리하여 기공크기가 15 nm정도인 3층 복합막을 제조 하였다. SEM, Bubble Point Test, Mercury Porosimeter 그리고 분획 분자량 측정등에 의하여 복합막의 코팅층 두께, 결함유무 및 막의 기공크기등을 분석하였다.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.3
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• pp.226-231
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• 2008

Cu/Fe/$Al_2O_3$ granules with various sizes have been prepared by a combination of sol-gel and oil drop method for the use in sulfur trioxide decomposition, a subcycle in thermochemical sulfur-iodine cycle to split water in the hydrogen and oxygen. The size of composite granules have been mainly changed by the flow-rate of the gel mixture before dropping in the synthesis. The structural properties of the samples were comparable with granule size. In the reaction, the catalytic activity was enhanced by decreasing size in the entire reaction temperature ranges.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.79-85
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• 1997

In order to improve the surface characteristics of polymethylmethacrylate(PMMA), oxide thin film coatings were applied using the sol-gel dip-coating technique. The $Si(OC_2H_5)_4$, tetra-ethyl-ortho-silicate(TEOS) was used as a starting material for $SiO_2$ coating. The hardness of the alkoxy-derived oxide-coated PMMA was increased from 190 MPa for non-coated PMMA with increasing film thickness. By optimizing the heating conditions and the hydrolysis conditions, a maximum apparent hardness obtained In the present study was achieved 310 MPa using the withdrawal velocity of 5cm/min and heat treatment at $90^{\circ}C$ for 5 hours, which is about 1.6 times larger than that of uncoated PMMA.

• Journal of the Korean Applied Science and Technology
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• v.20 no.4
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• pp.346-352
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• 2003

BaTiO$_3$, powders were prepared by sol-gel process from different aging time and reaction temperature. Particle shape, size and crystal structure of prepared $BaTiO_3$ powders were analyzed by SEM, XRD and FT-IR. Effect of aging time alternation didn't particularly show up. Spherical nano-sized $BaTiO_3$ powders were obtained from condition more than reaction temperature $55^{\circ}C$, and obtained sintered $BaTiO_3$ powders of tetragonal phase from heat-treatment at $1,100^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.765-773
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• 2000

The degradation of humic acid using $TiO_2$ coatings was studied, $TiO_2$ coatings were prepared by dip-coating method. Sol solutions for coating were prepared by mixing the gel, which can be produced by the reaction of $TiOCl_2$ and $NH_4OH$ solution, and hydrogen peroxide solution, and hydrolysis of titanium tetraisopropoxide (TTIP). It was shown from XRD that coatings from sol aged at $100^{\circ}C$ for 18h with titanium peroxo solution were crystallized to anatase in the range of temperatures of $25^{\circ}C$ to $500^{\circ}C$. In contrast, those coated from TTIP were crystallized to anatase at temperature above $400^{\circ}C$. So the sols originated from $TiCl_4$ can be applied for not only on the heat-resistance substrates but on the plastic substrates. Thickness and the quality of the films were dependent on the withdrawing speed, the concentration of sol, and the number of coating. The films showed various interference colors depending on the thickness of them. In the case that the films coated 2 times at withdrawing speed of 2.5cm per minute by 0.2M sol, the films had a transparent light blue color with thickness of around 50nm. It was known from the result of photo-degradation by $TiO_2$ coatings using humic acid that the removal efficiency of $COD_{cr}$ was over 85% after illumination of $UV/H_2O_2$ for 40min. and that of UV/VIS absorbable materials was over 95%.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.53-58
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• 2012

In order to improve the surface hardness of transparent plastic films, an organic-inorganic hybrid coating solution was sunthesized by the sol-gel method. Coating solutions that were prepared colloidal silica (CS), poly methyl methacrylate (PMMA), vinyltrimethoxysilane (VTMS), and [3-(methacryloyloxy)]propyltrimethoxy silane (MAPTMS) was varied with synthesizing parameters such as kinds of organic silane and weight ratio of CS to PMMA. Such coating solution was bar coated on the PET film, cured, and investigated on the chemical and physical properties of coating film. The organic-inorganic hybrid coating solutions have better properties at the pencil hardness and adhesion of coating film than those of an organic material such as PMMA.