• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2459-2464
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• 2007

In present study, a temperature field of specimens which was coated with fluorescence dye such as Rhodamine-B(Rh-B) has been measured, based on the fluorescence intensity. Silica(SiO2) nano porous structure with 1um thickness was constructed on a cover glass, and fluorescence dye was digested into these porous thin films. To optimize manufacturing coating process, various solvents, Rh-B concentration, and other chemical materials were applied to fabricate the specimen and all specimens were measured on the various temperature conditions. For the measurement, a 14 bit cooled CCD camera with 1600 by 1200 spatial resolution is equipped with epifluorescence microscope to obtain only fluorescence intensity from 1.2 mm by 0.9 mm field of view of the illuminated coated specimen.

• Journal of the Korean Ceramic Society
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• v.29 no.6
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• pp.496-504
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• 1992

Alumina tubes suitable for the support of gas separation membranes have been prepared by the slipcasting technique. These supports have the average pore size of 0.1 ${\mu}{\textrm}{m}$ within the narrow distribution. The sol-gel dipcoating process of nanoparticulate sols is very sensitive to microstructure of the support, and the coating on the inside surface of the tube is found to be more successful than on the outside surface. Nanoparticulate silica sols (0.82 mol/ι) have been synthesized by an interfacial hydrolysis reaction between TEOS and high alkaline water. When coating an alumina tube with these sols, the minimum limits of the particle size and the aging time required for forming the coated gel layer at the given pH are provided. It is optimum to coat the support with less concentrated sols stabilized through aging for the appropriate time (more than 22 days) at the lower pH (pH 2.0) for producing a reproducible crack free thin film coating in composite membranes.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.131-131
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• 2003

The advent of photonic technologies in the field of communications and data transmission has been heavily increasing the demand in integrated optical (IO) circuits capable of accomplishing not only simple tasks like signal, but also more sophisticated functions like all-optical signal routing or active multiplexing/demultiplexing. In the last decade, sol-gel technology has been widely used to prepare optical materials. Sol-gel processes show many promises for the development of low-loss, high-performance glass integrated optical circuits. However, crack formation is likely to occur during heat treatment in thick gel films. In order to overcome the critical thickness limitation, the organic-modified silicate has been widely used. In this case coating matrices have been prepared from the organo-silanes of T structures, acidic catalyst and the as-prepared gel films have been heat-treated below 200$^{\circ}C$ to avoid the crack formation and the degradation of organic components. However, the films prepared in the acidic condition and the low heat temperature make the films contain high OH groups which is the major optical loss function. In this work, C$\sub$6/H$\sub$5/SiO$\sub$1.5/ films were prepared on silicon substrate by sol-gel method using base catalyst in a PTMS/NH$_4$OH/H$_2$O/C$_2$H$\sub$5/OH system. The sol showed spinable viscosity at 50 wt% of solid content, and neglectable viscosity change with time. The films were crack-free and transparent after curing at 450 $^{\circ}C$, and highly condensed to minimize OH content in C$\sub$6/H$\sub$5/SiO$\sub$1.5/ networks. The effects of heat treatment of the films are characterized on the critical thickness, the chemical composition and the refractive indices by means of SEM, FT-IR, TGA, prism coupler, respectively.

• Journal of the Korea Concrete Institute
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• v.27 no.1
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• pp.21-28
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• 2015

Recent studies on concrete floating structure development focused on connection system of concrete modules. Precast concrete modules are designed to be attached by prestressing in the water, exposing the structure to the loads from water and making the construction difficult. Therefore, a development of bond material became a key issue in successful connection of floating concrete modules. In this study, micro-silica mixed aqua epoxy (MSAE) is developed for the task. Existing primer aqua epoxy, originally used as a bond material for the retrofit of concrete structures using fiber reinforced polymers, is evaluated to find the optimum micro-silica added mix proportion. Micro-silica of 0~4 volume % was mixed in standard mixture of aqua epoxy. Then, the material property tests were performed to study the effect of micro-silica in aqua epoxy by controlling the epoxy silane proportion by 0, ${\pm}5$, ${\pm}10%$. The optimum mix design of MSAE was derived based on the test results. The MSAE was used to connect concrete module specimens with the epoxy thickness variation of 5, 10, and 20mm. Then, 3-point loading test was performed to verify the bond capacity of MSAE. The results show that MSAE improves the bond capacity of concrete module.

• Analytical Science and Technology
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• v.26 no.4
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• pp.228-234
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• 2013

Methamphetamine is an amine-containing illegal drug and is distributed unlawfully in South Korea. Finding a rapid, convenient and semi-quantitative determination method for methamphetamine is a very important issue in the area of forensic drug testing. As an effort to develop new screening method, the reactions between three organic compounds which are structurally similar to methamphetamine and N-(9-fluorenylmethoxycarbonyloxy) succinimide (FMOC-NHS) were performed on silica gel ($SiO_2$) TLC plates. Three reference compounds were synthesized and used for the identification, comparison and study of the limit of detection (LOD) of the products obtained from a direct reaction on a TLC plate. As a result, FMOC-NHS as a derivatization reagent generated compounds containing highly UV-active functional groups on the TLC plate after reacting with primary- and secondary amines. In the experiment 2D the LOD of amines was in the range of 0.045 and 0.01 mg/mL ($2{\mu}L/spot$), and in 1D the LOD was in the range of 0.002 and 0.007 mg/mL ($2{\mu}L/spot$). The LODs of the compounds tested were dependent on the concentration of the derivatizing reagent.

• Economic and Environmental Geology
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• v.39 no.1 s.176
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• pp.1-7
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• 2006

This paper attempts to locate and define a quartzite deposit in Geochang, Kyongsangnam Province in order to establish its commercial viability. The quartzite deposit (Poongwon Mine) occurs as lens or boudinage at the contact between mica schist of the Deogyusan formation and granite gneiss. During Precambrian, regional metamorphism and granitization may have caused the formation ot quartzite layers through recrystallization and rearrangement of silica components derived from older sedimentary rocks, probably chert and/or sandstone. The deposit is composed of fine-grained milky, or light yellowish quartz showing weak laminations with fairly dense and rough appearance in outcrop. It reaches about $60\;m(height)\times140\;m(length)\times35m(width)$ with attitude of $N57^{\circ}E-N8^{\circ}4E\;and\;51^{\circ}-60^{\circ}NW$. The average grade of the quartzite samples is $SiO_2=94.4\;wt\%,\;A1_2O_3=3.3\;wt\%,\; Fe_2O_3=0.8\;wt\%,\;K_2O=0.7\;wt\%$, which can be used for foundry, constructional materials, or concrete making. The proved reserve was estimated as 200,811 tonnage.

• Tuberculosis and Respiratory Diseases
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• v.45 no.4
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• pp.823-834
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• 1998

Background: Chronic inhalation of silica induces the lung fiborsis. The alveolar macrophages ingest the inhaled silica; they liberate the pro-inflammatory cytokines such as IL-1$\beta$, IL-6, TNF-$\alpha$ and fibrogenic cytokines, TGF-$\beta$ and PDGF. Cytokines liberated from macrophage have pivotal role in pulmonary fibrosis. There is a complex cytokine network toward fibrosis. However, the exact roles and the interaction among the proinflammatory cytokines and TGF-$\beta$, a fibrogenic cytokine, have not been defined, yet. In this study, we investigated silica induced IL-1$\beta$, IL-6, TNF-$\alpha$ and TGF-$\beta$ production and the effect of IL-1$\beta$, IL-6, TNF-$\alpha$ on the production of TGF-$\beta$ from lung macrophages of Balb/C mice. Method: We extracted the lung of Balb/C mice and purified monocytes by Percoll gradient method. Macrphages were stimulated by silica ($SiO_2$) in the various concentration for 2, 4, 8, 12, and 24 hours. The supernatants were used for the measurement of protein levels by bioassay, and cells for the levels of mRNA by in situ hybridization. Results: The production of IL-6 was not observed till 4 hours, and reached the peak levels at 8 hours after stimulation of silica. The production of TNF-$\alpha$ increased from 2 hours and reached the peak levels at 4 hours after stimulation of silica. The spontaneous TGF-$\beta$ production reached the peak levels at 24 hours. TNF-$\alpha$ upregulated the silica induced TGF-$\beta$ production. Silica induced TGF-$\beta$ production was blocked by pretreated anti-TNF-$\alpha$ antibody. In situ hybridization revealed the increased positive signals at 4 hours in IL-6, at 4 hours TNF-$\alpha$ and 12 hours in TGF-$\beta$. Conclusion: The results above suggest that silica induced the sequential production of IL-6, 1NF-$\alpha$ and TGF-$\beta$ from macrophages and TNF-$\alpha$ upregultaes the production of TGF-$\beta$ from silica-induced macrophages.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.2
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• pp.65-72
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• 2012

Aluminum induced crystallization of amorphous silicon was attempted by the aluminum substrate. To avoid the layer exchange between silicon and aluminum layer, Ni layer was deposited between these two layers by sputtering. To obtain the bigger grain of the crystalline silicon, wet blasted silica layer was employed as windows between the nickel and a-Si layer. Ni obtained after the annealing treatment at $520^{\circ}C$ was found to be a promising material for the diffusion barrier between silicon and aluminum. One way to obtain bigger grain of crystalline silicon layer applicable to solar cell of higher performance was envisioned in this investigation.

• Journal of Applied Biological Chemistry
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• v.59 no.4
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• pp.357-360
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• 2016

Chrysanthemum morifolium flowers were extracted with 80 % aqueous MeOH, and the concentrated extract was partitioned into EtOAc, n-butyl alcohol (n-BuOH), and water fractions. The repeated silica gel and octadecyl silica gel column chromatographies for the EtOAc and n-BuOH fractions led to isolation of four flavonoids. The chemical structures of the compounds were determined as acacetin (1), apigenin (2), apigenin-7-O-${\beta}$-$\small{D}$-glucopyanoside (3), acacetin-7-O-${\beta}$-$\small{D}$-glucopyranoside (4) based on spectroscopic data analyses including nuclear magnetic resonance, mass spectrometry, and infrared spectrometry.

• Journal of the Korean Ceramic Society
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• v.34 no.3
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• pp.233-240
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• 1997

The Ru-based thick film resistor(TFR) for sintering at 90$0^{\circ}C$ was synthesized to prepare the LCR net-work. These compositions of pyrochlore could be prepared by decreasing the amount of PbO and increasing alumina and silica contents of glass frit. In this study, the sheet resistances of the TFTs. which sint-ered at 90$0^{\circ}C$ after printing on alumina substrate, the sheet resistances of the TFRs on inductor and capa-citor substrate and the interphase between TFR and substrate were observed. And the changes of the sheet resistance were obtained with the contents of RuO2. In case of the TFR sintered at 90$0^{\circ}C$, the sheet resis-tances on alumina substrates were in the range of 103~106$\Omega$/$\square$, but the sheet resistances of TFR on in-ductor and capacitor substrate were not obtained.