• Journal of the Korea Institute of Building Construction
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• v.12 no.1
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• pp.54-63
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• 2012

The purpose of this study is to examine the potential for reducing the environmental load and $CO_2$ gas when cement is produced by using cement substitutes. These substitutes consisted of blast furnace slag, red mud and silica fume, which were industrial by-products. The most optimum mix was derived when alkali accelerator was added to low carbon inorganic composite mixed with industrial by-product at room temperature. It is determined that hardened properties and the results of compressive strength tests changed based on CaO content, Si/Al, the mixing ratio and the amount of alkali accelerator, curing conditions and W/B. The results of test analysis suggest that the optimum mix of low carbon inorganic composite is CaO content 30%, Si/Al 4, the mixed ratio of alkali accelerator $(NaOH:Na_2SiO_3)$ 50g:50g, the amount of alkali accelerator 100g and W/B 31%. In addition, if contraction is complemented, low carbon inorganic composite with superior performance could be developed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.514-520
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• 1997

A single component of $Sb_2O_3$ glass has been obtained by a rapid quenching method in vacuum. The linear refractive indices were measured as a function of wavelength from 500 nm to 1060 nm. The refractive index at $n_{3{\omega}}$/(633 nm) was as high as 2.00. The optical band gap was estimated as 3.38 eV from the optical absorption spectrum. The third-order nonlinear optical intensity was determined by the third harmonic generation (THG) method. The $\chi^{(3)}$value was as high as $5.68{\times}10^{-13}$esu, about 20 times larger than that of $SiO_2$ glass.

• Magazine of the Korea Concrete Institute
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• v.9 no.5
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• pp.127-135
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• 1997

This paper is an experimental study of the acid-resistance of concrect which contains silica sand particles. In the concerete sample experiment. the workability and strengh as well as the acid-resistance of the hardended concrect is inverstigated.

• Journal of Radiation Industry
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• v.5 no.4
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• pp.305-311
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• 2011

We introduced a novel sustainable slow-releasing agrochemical formulation, a biopolymer bound to silica, for controlling plant diseases. The formulation was obtained through the following process. Curdlan, sodium silicate ($Na_2SiO_3$) and isopropyl alcohol were dissolved in DDW (Deionized-distilled water). The resultant solution was then irradiated using a $^{60}Co$ ${\gamma}$-irradiator (150 TBq of capacity; ACEL, Canada) at KAERI. The resultant solution was treated with phosphorous acid ($H_3PO_3$). Finally, we obtained a novel biopolymer-silica microsized formulation containing phosphorous acid ($H_3PO_3$) from the solution. The morphology of the complex was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM images revealed that the curdlan-silica formulation has a particle size ranging from 1 to $3{\mu}m$ with high stability. We also detected that $H_3PO_3$ was distributed within the formulation through energy dispersive X-ray spectroscopy (EDX) analysis. $H_3PO_3$ was sustain-released from the formulation in water. Based on our results, it seems effectively that one or two applications of the formulation during a cropping season will assist in controlling various plant diseases.

• Korean Journal of Soil Science and Fertilizer
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• v.3 no.1
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• pp.1-10
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• 1970

A pot experiment of paddy rice was carried out primarily to find out the effect of potash in relation to the application of wollastonite on paddy rice. The result which showed increased paddy rice yield has been evaluated from the factors of yield, yield components, soil and plant analysis data at different stages of plant growth and the summary of review is described as follows : 1. Effect of potash is likely to be greater in the presence of wollastonite and a larger quantity of wollastonite application would require correspondingly larger quantities of potash. 2. Application of potash and wollastonite resulted increased paddy rice yield may be largely due to increased contents of potassium, calcium and silica in the soil and increased concentration of $K_2O$, CaO and $SiO_2$, $SiO_2/N$ ratio and $K_2O/N$ ratio in rice straw. 3. The maximum paddy rice yield, at less than 300kg/10a application of wollastonite was obtained by applying 8kg of $K_2O$ per 10 are while 600kg/10a application of wollastonite gave the maximum yield by applying 16kg of $K_2O$ application per 10 are. 4. Application of wollastonite decreased the number of ears per hill and number of grains per ear. While ripening percentage and 1,000 grain weight tended to increase with wollastonite. The increased contents of CaO and $SiO_2$ in straw due to wollastonite application showed a negative correlation with the number of ears per hill and the number of grains per ear but a positive correlation was shown with ripening percentage and 1,000 grains weight. 5. Potash application appeared to be increasing the number of ears per hill and the number of grains per ear. There was a positive correlation exist between the higher content of $K_2O$ in rice straw and the number of grains per ear 6. Amount of nitrogen absorbed tended to decrease with increase in quantities of potash and wollastonite but the ratio of $SiO_2/N$ was increased by further application of potash and wollastonite. 7. $K_2O/N$ ratio was increased with incrementing in quantities of potash application but in the absence of potash, $K_2O/N$ ratio was decreased as to increasing wollastonite application.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.737-741
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• 2005

In this study, the effect of copper content on the NO removal efficiency by Cu/MCM-41 has been investigated. MCM-41 was prepared by hydrothermal synthesis using a gel mixture of colloidal silica solution and cetyltrimethylammonium. Cu/MCM-41 was manufactured with copper content (5, 10, 20, and 40%) in Cu(II) acetylacetonate. The surface properties of MCM-41 were investigated by using pH, XRD, and FT-IR analyses. $N_2/77K$ adsorption isotherm characteristics, including the specific surface area and micropore volume were studied by BET's equation and Boer's t-plot methods. NO removal efficiency was confirmed by gas chromatography technique. From the experimental results, the MCM-41 was analyzed to have the surface functional groups of Si-OH and Si-O-Si and the characteristic diffraction lines (100), (110), (200), and (210) corresponding to a hexagonal arrangement structure. The copper content supported on MCM-41 appeared to increase the NO removal efficiency in spite of decreasing the specific surface areas or micropore volumes. Consequently, it was found that the copper content in Cu/MCM-41 played an important role in improving the NO removal efficiency, which was mainly attributed to the catalytic reactions.

• Journal of Applied Biological Chemistry
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• v.59 no.2
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• pp.155-158
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• 2016

The fruits of Prunus davidiana were extracted with 80 % aqueous methanol at room temperature. The concentrated extract was partitioned as ethyl acetate (EtOAc), n-butyl alcohol, and water fractions. From the EtOAc fraction, three triterpenoids were isolated through the repeated silica gel ($SiO_2$) and octadecyl $SiO_2$ column chromatographies. Based on physico-chemical and spectroscopic data including nuclear magnetic resonance, mass spectrometry, and infrared, the compounds were identified to be ursolic acid (1), corosolic acid (2), and ${\alpha}-amyrin$ (3).

• Economic and Environmental Geology
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• v.31 no.3
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• pp.249-264
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• 1998

The Creataceous volcanic rocks distributed in the southeastern part (Kyeongsang basin) of Korea peninsula are composed of basalt, basaltic andesite, andesite, dacite and rhyolite. The variation of major elements show that contents of MgO, CaO, $FeO^T$, $Al_2O_3$, $TiO_2$ and $P_2O_5$ decrease with increasing of $SiO_2$, but $K_2O$ contents are increased slightly, $Na_2O$ widely dispersed. We can show slightly inflection point and low frequency of dacites in range between 63-65 wt.% $SiO_2$, while continuous trend exit in variation diagram. Variation trends in Harker diagrams for the major, minor, trace and REEs suggest that the BAV (basaltic to andesitic volcanics) and DRV (dacitic to rhyolitic volcanics) are not related to a simple crystal fractionation process. In the regime of under 65 wt. % in silica content, fractionation of olivine and clinopyroxene is predominant, while that of plagioclase happens strongly higher than 65 wt.% (e.g., $SiO_2$, vs. Eu and Sr, MgO vs. $Al_2O_3$ and CaO). The latter means low-pressure fractional crystallization for DRV. On the discriminant diagram, DRV are located in more mature environment than BAV. The $(Ce/Sm)_N$ vs. CeN digram shows that these two classes cannot be related to crystal fractionation. If they had been produced by fractionation, although they plotted in a slightly elongate cluster along the same horizontal trend, DRV should lie to the right of these primitive compositions. These diagrams clearly rule out a simple fractionation throughout from BAV to DRV. BAV had been influenced greatly subductiong slab as shown by K/Yb vs. Ta/Yb. We suggest that BAV primitive magma generated higher degree of partial melting than DRV primitive magma. LILE (K, Ba, $Rb{\pm}Th$) enriched characteristics as shown in BAV are inherited from subducting slab fluids and/or higher degree of partial melting of mantle material. However, lower degree of partial melting of mantle relative to BA V and contamination at high-level magma reservoir caused LILE enrichment to DRV.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.143-148
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• 2018

Sodium silicate based silica aerogels are lower in cost than silica alkoxide based silica aerogels, but the demand is decreasing as their physical properties are lowered. In this research, acetonitrile as a drying control chemical additive (DCCA) is added in the sol state to improve the pore-structural properties of sodium silicate based silica aerogel by preventing the agglomeration of particles and cross-linked bond. The sodium silicate based silica aerogel by ambient pressure drying were prepared by sol-gel process. Acetonitrile/$Na_2SiO_3$ molar ratio of 0, 0.05, 0.1, 0.15, and 0.2 was added to the sol state. The physical properties of the final product were analyzed using Fourier transform infrared, contact angle measurement, Brunauer-Emmett-Teller and Barrett-Joyner-Halenda measurements and field emission scanning electron microscopy. It was confirmed that the sample with adding 0.15 molar ratio of acetonitrile and sodium silicate showed a high specific surface area ($577m^2/g$), a high pore volume (3.29 cc/g), and a high porosity (93%) comparable to the pore-structural properties of silica alkoxide based silica aerogels.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1124-1125
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• 2006

Dry sliding wear behavior of electro-pressure sintered Co-Fe, Co-Ni and Co-Fe-Ni compacts was investigated. Pin-on-disk wear tests were performed on the sintered compacts disk specimens against alumina $(Al_2O_3)$ and silica $(SiO_2)$ ball counterparts at various loads ranging from 3N to 12N. Two sliding speeds of 0.1m/sec and 0.2m/sec and a fixed sliding distance of 1,000m were employed. Worn surfaces and cross sections of them were examined by a scanning electron microscopy, and wear mechanism of the compacts was investigated. Effects of the oxide layer that was formed on wearing surface of the compacts on the wear were also studied.