• 한국염색가공학회지
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• 제24권4호
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• pp.313-320
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• 2012

For the preparation of hardened films which can be applied as a binder for flame-resistant materials such as silica, linseed oil was subjected to a low temperature plasma treatment with argon, or oxygen gas. The film was produced much faster than so-called drying of oil in air. The SEM analysis for silica particles embedded in the hardened film after plasma treatment showed that the silica particles were immobilized on substrate and were evenly dispersed. The FT-IR spectral analysis for the plasma-treated linseed oil films demonstrated that the radicals which were formed during the plasma treatments caused the linseed oil to be cross-linked, and the plasmas attacked carbon chains of the oil randomly without focusing on specific vulnerable bonds such carbon double and carbonyl bonds intensively unless exposure times of the plasmas were prolonged too much, while the cross-linking of the air-dried film was considered to occur at the well-known typical sites, i.e., carbon-carbon double bond and ${\alpha}$-methylene carbon. Burning times, as a measure of flame/fire resistance, of silica-filled cellulose substrates, increased with increasing contents of silica.

• 한국염색가공학회지
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• 제26권4호
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• pp.297-304
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• 2014

In this study, we investigated the relationship between the adsorption property of Methyl violet or Tartrazine dye onto silica sol surface and surface charge density of the sol. The adsorption ratio of Methyl violet dye on silica sol decreased to 74% and 92% for the 68nm and 94nm silica sol, respectively, at dye concentration of $175{\mu}g/m^2$. However, the adsorption ratio of Tartrazine dye on 68nm and 94nm silica sol was about 0% for both of them. The surface charge density is $-0.40C/m^2$, $-0.26C/m^2$ for 68nm and 94nm silica sol, respectively. The amount of Methyl violet dye adsorbed on silica sol increased with an increase of surface charge density of particle at the same concentration of the dye. The adsorbed amount of the silica having high surface charge density is larger at high pH domain. But adsorbed amount of the silica having low surface charge density is larger at low pH domain.

• 공업화학
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• 제20권6호
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• pp.685-691
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• 2009

하이드록시기 유무, 극성도, 분자 크기가 서로 다른 용매 6종의 단일 용매 또는 혼합 용매계 흄드 실리카 분산체를 제조하고 각 분산체의 점도 및 유변학적 거동을 용매계의 특성의 관점에서 고찰하였다. 하이드록시기 포함 용매에 실리카를 분산하였을 때 안정적이고 저점도의 sol을 형성하였고 하이드록시기가 없고 비극성인 용매는 고점도의 gel을 형성하였다. 비극성 용매계 실리카 분산체에 하이드록시기 함유 용매를 첨가하면 일정 함량까지는 점도 감소 현상을 관찰할 수 있었으며, 더 이상의 점도 변화가 발생하지 않는 최소 임계함량이 있었다. 최소 임계함량은 하이드록시기 미포함 용매의 극성도가 클수록 줄어들었다. 하이드록시기 포함 용매계 실리카 분산체가 안정적인 저점도의 sol을 형성하는데 이는 실리카 표면의 실란올기와 용매의 하이드록시기간의 수소결합을 통한 용매화로 저점도 sol을 형성하는 것으로 볼 수 있다. 비극성용매에 실리카를 분산하였을 때는 실리카 표면의 실란올기 사이의 수소 결합을 통해 응집이 일어나 고점도의 gel이 형성되었다.

• 한국세라믹학회지
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• 제54권5호
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• pp.429-437
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• 2017

Micro hollow plate type silica with low refraction properties was synthesized and its hollow structure was applied as an optical structure to develop a light diffusion material that simultaneously satisfies the requirements of good light diffusibility, high transmissibility, and high luminance. The developed light diffusion material was applied to a light diffusion film and the film's optical properties were assessed. Hollow silica was synthesized by precipitation method using $Mg(OH)_2$ core particles, sodium silicate, and ammonium sulfate as the silica precursors. The concentration of the silica precursor was adjusted to control hollow silica shell thickness. The total light transmittance of the light diffusion film composed of the hollow silica was 94.55%, which was 4.57% higher than that of the PC film; new film's haze was 71.20%, which was 70.9% higher. Furthermore, the luminance increased by 5.34% compared to that of the light source. The reason for the results is not only that the micro plate type hollow silica, which has a low refractive property, played a role in reducing the difference in refractive index between the medium boundaries, but also that there was a light-concentrating effect due to the changing of light paths to the front direction inside the hollow structure. Optical simulation verified the enhanced optical properties when hollow silica was applied to the light diffusion film.

• 한국토양비료학회지
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• 제4권1호
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• pp.1-11
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• 1971

1. 규산시용(珪酸施用)으로 수도(水稻)의 출수(出穗)가 수경(水耕)과 추낙답(秋落畓)에서 공(共)히 약(約) 일주일(一週日)이 빨렀고 수도(水稻)의 엽(葉)은 현저히 직립(直立)되였다. 2. 규산시용(珪酸施用)으로 수도(水稻)의 규산함량(珪酸含量)이 증가(增加)하며 추낙답(秋落畓)에서는 규산(珪酸)을 박비(迫肥)보다 기비(基肥)로 시용(施用)하는 것이 수도(水稻)의 규산함량(珪酸含量)을 증가(增加)시켰다. 규산시용(珪酸施用)으로 다른 양분(養分)의 함량(含量)은 감소(減少)되는 경향(傾向)이며 특(特)히 추락도(秋落稻)의 Fe 함량(含量)은 현저히 감소(減少)되었다. 3. 수도(水稻)의 규산함량(珪酸含量)과 엽도열병(葉稻熱病), 호마엽고병(胡麻葉枯病), 응애 및 멸구의 저항성(抵抗性)과는 부(負)의 상관(相關)이 있다. 4. 수도(水稻)에 대(對)한 규산(珪酸)의 증수효과(增收效果)는 수경(水耕)에서는 거의 없으나 추낙답(秋落畓)에서는 현저하다. 추낙답(秋落畓)에 대(對)한 규산(珪酸)의 증수효과(增收效果)는 pot 재배(栽培)보다 포장(圃場)에서 더 현저하다. 규산시용(珪酸施用)으로 추낙도(秋落稻)의 수당입수(穗當粒數)와 등숙률(登熟率)이 높아지고 규산(珪酸)의 비효(肥效)는 질소(窒素)와 가리(加里)의 균형시비(均衡施肥)로 증가(增加)한다. 5. 따라서 규산(珪酸)은 수도(水稻)에 대(對)한 필수원소(必須元素)라기보다 추낙답(秋落畓)과 같이 가급태규산함량(可給態珪酸含量)이 적은 토양(土壤)에서는 수도(水稻)의 건전생육(健全生育)을 위(爲)하여 농경학적(農耕學的) 의미(意味)에서 규산(珪酸)의 공급(供給)이 필요(必要)하다고 생각(生覺)된다.

• 한국세라믹학회지
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• 제45권7호
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• pp.395-400
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• 2008

This paper indicates the investigation about the development of ET (Environmental Technology) industrial geopolymeric materials from mixture silica mine waste, coal fly ash and alkali activator solution (sodium silicate) by the geopolymer technique at ambient temperature. The results showed that higher compressive strength of geopolymeric mortar increased with a reduce of L/S ratio and increased along with an increase of coal fly ash content. The compressive strengths of geopolymer mortar on low silica of C Silica Mine and K Silica Mine are 18.7 MPa, 20.4 MPa, respectively. Compressive strength of geopolymeric mortar depends on L/S ratio and coal fly ash content added.. Additionally, scanning electron microscope (SEM) techniques are used to characterize the microstructure of the geopolymeric mortars. SEM observation shows that it is possible to have amorphous aluminosilicate gel within mortar. XRD patterns indicate the fact that geopolymeric mortar is composed of amorphous aluminosilicate phase, calcite and quartz.

• Elastomers and Composites
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• 제38권1호
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• pp.65-71
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• 2003

저분자량 SBR (액상 SBR)이 실리카로 보강된 SBR 배합물의 특성에 미치는 영향에 대해 연구하였다. 액상 SBR을 실리카로 보강된 SBR 배합물에 첨가하면 점도가 낮아졌다. 가교밀도는 액상 SBR의 함량이 증가함에 따라 감소하였고 가창속도는 느려졌다. 모듈러스와 인장강도는 액상 SBR의 함량이 증가할수록 낮아졌고 신율은 증가하였다. 마모 특성은 액상 SBR의 함량에 따라 큰 차이를 보이지 않았다. 이는 액상 SBR의 첨가에 의해 실리카 분산이 향상되었기 때문으로 여겨진다. 실험결과를 종합해 볼 때, 5 phr 이하의 적은 양의 액상 SBR을 사용하는 것이 실리카로 보강된 SBR 배합물의 특성을 향상시키는데 바람직할 것으로 판단된다.

• Journal of Information Display
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• 제8권1호
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• pp.14-17
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• 2007

The toner type paper-like display (PLD) has been developed with two polymer particles having opposite polarity composed of polymer, colorant and external additives (nano-sized silica). Nano-sized silica with triboelectric charge was used for the charge control agent (CCA) and influenced on the electrostatic properties of the silica-coated polymer particles. The surface morphology and the cohesiveness of silica-coated polymer particles were changed with the silica coating time. From these results, it was verified that the PLD cell using silica-coated particles (200 seconds) shows a good white appearance and low driving voltage.

• Journal of Ceramic Processing Research
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• 제13권spc1호
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• pp.78-81
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• 2012

Colloidal titania nanoparticles were synthesized by a simple sol-gel process. The obtained nanoparticles showed high crystallinity and were of the anatase type. These crystalline colloidal titania nanoparticles were organically modified using methyl- and glycidyl-grafted silanes in order to enhance their stability and solution processability. The stabilized colloidal titania nanoparticles could be dispersed homogeneously without aggregation and converted into silica-titania hybrid films with the heterogeneous Si-O-Ti bonds by a low-temperature solution process. The fabricated silica-titania hybrid films showed high transparency (~ 90%) in the visible range, and low RMS roughness (<1 nm). Therefore, the organosilane-modified crystalline colloidal titania nanoparticles can be used in solution-processable functional coatings for electro-optical devices.

• Macromolecular Research
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• 제12권1호
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• pp.78-84
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• 2004

Advanced epoxy molding compounds (EMCs) should be considered to alleviate the thermal stress problems caused by low thermal conductivity and high elastic modulus of an EMC and by the mismatch of the coefficient of thermal expansion (CTE) between an EMC and the Si-wafer. Though A1N has some advantages, such as high thermal conductivity and mechanical strength, an A1N-filled EMC could not be applied to commercial products because of its low fluidity and high modules. To solve this problem, we used 2-$\mu\textrm{m}$ fused silica, which has low porosity and spherical shape, as a small size filler in the binary mixture of fillers. When the composition of the silica in the binary filler system reached 0.3, the fluidity of EMC was improved more than twofold and the mechanical strength was improved 1.5 times, relative to the 23-$\mu\textrm{m}$ A1N-filled EMC. In addition, the values of the elastic modules and the dielectric constant were reduced to 90％, although the thermal conductivity of EMC was reduced from 4.3 to 2.5 W/m-K, when compared with the 23-$\mu\textrm{m}$ A1N-filled EMC. Thus, the A1N/silica (7/3)-filled EMC effectively meets the requirements of an advanced electronic packaging material for commercial products, such as high thermal conductivity (more than 2 W/m-K), high fluidity, low elastic modules, low dielectric constant, and low CTE.