• Korean Journal of Soil Science and Fertilizer
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• v.4 no.1
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• pp.1-11
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• 1971

1. Rice plant grown with silica had more elect leaves and heading was one week earlier with silica than without silica grown in both water culture and Akiochi soil. 2. Silica content of rice plant was apparently increased by silica application and the increase insilica was more increased by bassal application of silica than top dressing. The content of other eements in plant decreased with silica application and the trend was most noticeable in iron. 3. Rice plant low in silica were more susceptible to reaf blast, Helminthosporium, mites and smaller brown plant hopper. 4. There was no significant effect of silica on increasing the dry matter production of rice plant grown on water culture, but silica remarkerbly increased the dry matter production of rice plant grown on Akiochi soil. The increasing effect of silica on rice grown on Akiochi fields was more noticeable than that of grown on Pots. 5. In rice plant grown on Akiochi soil, number of spikelets and percentage of ripened grains were increased by application of silica. The silica effects can be increased by application of well balanced nitrogen and potassium ratio. 6. From these results, it can be concluded that silica seems to have no direct effect on rice growth, but application of silica to Akiochi soil associated with low silica supply may be critical for healthy growth of rice plant, and silica directly related to rice agronomy.

• Bulletin of the Korean Chemical Society
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• v.6 no.2
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• pp.112-115
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• 1985

3-Aminopropylsilated silica gel bound hemin, biliverdin, and bilirubin were synthesized by reacting 3-aminopropyl silated silica gel with hemin, biliverdin and bilirubin respectively. The aspects of binding of bilirubin to amino group of 3-aminopropylsilated silica gel were studied using the above synthetic silica immobilized hemin, biliverdin and bilirubin, and oxodipyrromethene.

• Polymer(Korea)
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• v.36 no.6
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• pp.721-726
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• 2012

Thermoplastic polyurethane (TPU) elastomer is used as an encapsulant in undersea sonar devices. A new material for sonar encapsulant exhibiting better mechanical strength than TPU along with a lower swelling ratio for seawater and oil is required to prolong its application. TPU grafted silica nanoparticles (TPU-g-silica) were prepared and then they were melt mixed with TPU to fabricate desirable composites for underwater applications. The composite containing silica nanoparticles exhibited better tensile strength and lower swelling ratios in the seawater and oil than TPU regardless of the surface treatment of the silica particles. At fixed silica content in the composite, the TPU/TPU-g-silica composite exhibited better tensile strength and lower swelling ratio than the TPU composite with the pristine silica particles. Furthermore, the TPU/TPU-g-silica composite exhibited enhanced tensile strength as compared to TPU after being impregnated with oil.

• Geomechanics and Engineering
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• v.8 no.1
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• pp.113-132
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• 2015

In this study, lime (L), silica fume (SF), and lime-silica fume (L-SF) mix have been used for stabilizing and considering their effects on the soft clay soil. The improvement technique adopted in this study includes improving the behaviour, of a square footing over soft clay through grouting the clay with a slurry of lime-silica fume before and after installation of the footing. A grey-colored densified silica fume is used. Three percentages are used for lime (2%, 4% and 6%) and three percentages are used for silica fume (2.5%, 5%, 10%) and the optimum percentage of silica fume is mixed with the percentages of lime. Several tests are made to investigate the soil behaviour after adding the limeand silica fume. For grouting the soft clay underneath and around the footing, a 60 ml needle was used as a liquid tank of the lime-silica fume mix. Slurried silica fume typically contains 40 to 60% silica fume by mass. Four categories were studied to stabilize soft clay before and after footing construction and for each category, the effectiveness of grouting was investigated; the effect of injection hole spacing and depth of grout was investigated too. It was found that when the soft clay underneath or around a footing is injected by a slurry of lime-silica fume, an increase in the bearing capacity in the range of (6.58-88)% is obtained. The footing bearing capacity increases with increase of depth of grouting holes around the footing area due to increase in L-SF grout. The grouting near the footing to a distance of 0.5 B is more effective than grouting at a distance of 1.0 B due to shape of shear failure of soft clay around the footing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.4007-4012
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• 2014

This study examined the fabrication and thermal properties of fumed silica/ceramic wool inorganic composites. A predetermined quantity of fumed silica and ceramic wool was mixed uniformly into a slurry state and stabilized in the mold at room temperature, and converted to a massive foamed body through a complete drying process at $150^{\circ}C$. Although the samples without polyvinyl alcohol (PVA) as an interfacial adhesive showed a bulk density of 0.6-0.8 $g/cm^3$ in the range, 10-70wt% fumed silica, those samples with 3wt% PVA exhibited remarkably lower bulk densities with enhanced mechanical and thermal insulation properties, without thermal cracking even above $800^{\circ}C$. The K-factor of the samples was lower in proportion to the fumed silica contents, showing good thermal insulation properties of ca. 0.08 $W/m^{\circ}K$ at $500^{\circ}C$ for the sample with 30wt% fumed silica.

• Journal of the Korea Concrete Institute
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• v.25 no.3
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• pp.305-312
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• 2013

This paper reports the results of an investigation into the effects of silica fume on strength properties of alkali-activated slag cement (AASC) with water-binder (W/B) ratio and replacement ratio of silica fume content. The W/B ratio varied between 0.50 and 0.60 at a constant increment of 0.05. The silica fume content varied from 0% to 50% by weight of slag. The activators was used sodium hydroxide (NaOH) and the dosage of activator was 3M. The strength development with W/B ratio has been studied at different ages of 1, 3, 7 and 28 days. For mixes of AASC mortars with varying silica fume content, the flow values were lower than the control mixes (without silica fume). The flow value was decrease as the content of silica fume increase. This is because the higher surface areas of silica fume particles increase the water requirement. The analysis of these results indicates that, increasing the silica fume content in AASC mortar also increased the compressive strength. Moreover, the strength decreases with the W/B ratios increases. This is because the particle sizes of silica fume are smaller than slag. The high compressive strength of blended slag-silica fume mortars was due to both the filler effect and the activated reaction of silica fume evidently giving the mortar matrix a denser microstructure, thereby resulting in a significant gain in strength.

• Elastomers and Composites
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• v.33 no.3
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• pp.185-192
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• 1998

This study was investigated on the physical properties of synthetic rubber compounds containing silica and silane copuled silica. Surface area and pore volume of silane copuled silica appeared to be low compared with those of pure silica because silane coupling agent blocks the pore of silica surface during silanization reaction. Silica with large surface area and high structure showed the short scorch time$(t_5)$ and rapid cure rate. The silane coupled silica showed the shorter scorch time and more rapid cure rate than pure silica because of the of effect of sulfur in the silane coupling agent(Si 69), The high value of $N_2SA$ minus CTAB com-pared with surface area and structure of silica showed the high 300% modulus. Also, the surface area and structure of silica did not affected the amount of PICO loss that indicate the abrasion resistance but affected the amount of cut and chip loss.

• Journal of Applied Reliability
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• v.14 no.1
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• pp.11-19
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• 2014

A colloidal silica slurry has been manufactured by mixing nano silica powders having different grain size to improve the reliability of Sapphire wafer CMP process. The main reliability problem of CMP process such as the breaking of wafer can be prevented by reducing the size of particles in a slurry. While existing commercial colloidal silica slurries are usually made of single grain size silica powder of about 120nm, in the present study 40nm and 100nm silica powders are mixed to achieve a similar removal rate. The new colloidal silica slurry showed wafer removal rate of $3.04{\mu}m/120min$ while that of a commercial colloidal silica slurry was $3.03{\mu}m/120min$. The roughness was less than $4{\AA}$ and scratch was 0. It is also expected that the reduction of the size of nano silica particles can improve the dispersion stability and prolong the useful life of the slurry.

• ETRI Journal
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• v.25 no.2
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• pp.73-80
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• 2003

This paper describes an effective method for forming silicon oxide on silica-on-silicon platforms, which results in excellent characteristics for hybrid integration. Among the many processes involved in fabricating silica-on-silicon platforms with planar lightwave circuits (PLCs), the process for forming silicon oxide on an etched silicon substrate is very important for obtaining transparent silica film because it determines the compatibility at the interface between the silicon and the silica film. To investigate the effects of the formation process of the silicon oxide on the characteristics of the silica PLC platform, we compared two silicon oxide formation processes: thermal oxidation and plasma-enhanced chemical vapor deposition (PECVD). Thermal oxidation in fabricating silica platforms generates defects and a cristobalite crystal phase, which results in deterioration of the optical waveguide characteristics. On the other hand, a silica platform with the silicon oxide layer deposited by PECVD has a transparent planar optical waveguide because the crystal growth of the silica has been suppressed. We confirm that the PECVD method is an effective process for silicon oxide formation for a silica platform with excellent characteristics.

• Elastomers and Composites
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• v.36 no.1
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• pp.37-43
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• 2001

Influence of the filler composition ratio on cure characteristics and bound rubber content of the compounds and on physical properties of the vulcanizates were studied using both silica and carbon black-filled styrene-butadiene rubber (SBR) compounds with the total filler content of 80.0 phr. The bound rubber content increased slightly with increase of the silica content ratio. The viscosity also increased with increasing the silica content ratio, especially increased steeply after the silica content of 60.0 phr. The cure times obtained with a rheometer, t2, t40, and t90, are increased by increasing the silica content ratio and the cure rate decreased. The delta torque increased with the increased silica content ratio. Variation or the modulus with the silica content ratio showed a decreased trend though the delta torque increased. The tan ${\delta}$ at $60^{\circ}C$ decreased with increased of the silica content ratio.