• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.71-82
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• 1995

The weathered two-mica granite is widely distributed in Korea and called a kind of ground rock for kaolin. The major minerla compositions are consist of this quartz, feldspar, mica and clay mineral. At present, only a small portion of this granite is used as the material for the low-grade tile industry due to the low S.K. value and the high contents of impurities such as Fe2O3 and FeO. The low S.K. value is caused by feldspars not weathered to clay minerals. The refinement of this thus has been required for the recent shortage of the resources of high-grade one. This paper concerns an optimum hydrothermal treatment condition to refine the low-grade weathered two-mica granite of which impurities are feldspar mineral and Fe2O3. FeO components in using for the main material of ceramic industry. And then, from this result, we tried to fine out the basic formation mechanism of clay mineral from feldspar etc and develope the effectual utilization method of this.

• Journal of the Korean Applied Science and Technology
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• v.25 no.4
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• pp.511-517
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• 2008

We make high-functional inorganic-composite pearlescent pigment material that coated with carmine on the plate-type particle such as mica. In this experiment, we synthesized composite powder using pH control precipitation method. We make an experiment with changing as synthesis factors that are concentrations of starting material and precipitation materials. We analyzed pearlescent powder's shape, and crystallization with FE-SEM, XRD, and EDS. Optimum condition for preparation of carmine coated mica pearlescent pigment is pH $4.5{\sim}5.5$.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.459-459
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• 2011

Graphene has many fascinating material properties such as high electron mobility, high optical transparency, excellent thermal conductivity, superior Young's modulus, etc. Several studies have recently found that single-layer graphene is chemically more reactive than few-layer graphene when supported on silicon dioxide substrates with sub-nm roughness. In this study, we have investigated the influence of substrates on chemical reactivity of graphene. Morphology and thermal oxidation behavior of graphene on atomically flat mica substrates were studied by atomic force microscopy (AFM) and Raman spectroscopy compared to graphene on SiO2/Si substrates. Notably, oxidation of single-layer graphene proceeds more slowly on mica than SiO2/Si. Detailed analysis led to a conclusion that deformation along the out-of-plane direction enhances reactivity of graphene.

• Proceedings of the IEEK Conference
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• summer
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• pp.249-253
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• 2004

Wavelet transform (WT) has attracted most engineers and scientists because of its excellent properties. The coherence of practical approach and a theoretical basis not only solves currently important problems, but also gives the potential of formulating and solving completely new problems. It has been show that multi-resolution analysis of Wavelet transforms is good solution in speech analysis and threshold of wavelet coefficients has near optimal noise reduction property for many classes of signals. This paper proposed applications of wavelet in speech processing: pitch detection, voice-unvoice (V -UV) decision, denoising with the detailed algorithms and results.

• Journal of IKEEE
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• v.13 no.2
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• pp.194-199
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• 2009

In this study, ultra high-voltage (170kV AC), reliable 80pF mica capacitors for partial discharge system application were investigated. For capacitors design, Program was developed to sampling of series and parallel parameters. Mica was used as the dielectric of the capacitors. Using the conservative design rule, over 3 individual 50$\mu$m thick mica sheets with a size of 30mm$\times$35mm were used with lead foils to form a parallel capacitor element and 20 mica sheets were interleaved with lead foils to form a series stack of parallel capacitor element to meet the requirements of the capacitors. The dimension of the fabricated 80pF capacitor for 17kV AC were 90mm$\times$90mm. The high-frequency characteristics of the capacitance (C) and dissipation factor (D) of the developed capacitors were measured using a capacitance meter. The developed capacitor exhibited C of 79.5pF, had D of 0.001% over the frequency ranges of 150kHz to 50MHz, had a self-resonant frequency of 65MHz.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.4
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• pp.172-178
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• 2007

Mica (muscovite) powders were synthesized by hydrothermal method (horizontal turning method). The hydrothermal conditions for the synthesis of mica were prepared by the ratio of $K_2O : Al(OH)_3 : SiO_2$ = 1 : 3 : 3 mol% as the starting materials with KOH (8 mol%) solution as the hydrothermal solvent and reaction temperature at $260^{\circ}C$ for 72hrs. The synthetic powder used for preparation of nano silver coated mica by vertical hydrothermal treatment. The hydrothermal conditions for the treated as nano silver coating were prepared by the synthetic powder as raw materials, triple distilled water ($0.5{\ell}$) solution as the hydrothermal solvent with nano silver sol (1,000 ppm) as the material of nano silver coating and reaction temperature at $160{\sim}260^{\circ}C$ for 72 hrs. After hydrothermal treatment, structural, judgment of nano silver coating and character of nano silver coated mica were examined by XRD, SEM, TEM-EDX and shake plask method.

• The Journal of Engineering Geology
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• v.19 no.3
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• pp.287-294
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• 2009

To be design the slope, the area distributed the mica schist which was metamorphosed by shale or mudstone must carefully consider the stability. Mica schist is another unstable rock for slope by schistosity, cleavage, axial plane of a fold etc. In general mica schist contains the swelling clay minerals such as smectite, vermiculite and montmorillonite. These minerals make the slope unstable. At OO tunnel construction area for the rail way of the Kyungbu high speed train, the slope of mica schist is very unstable by the distribution phenomena of the discontinuous plane such as joints which are 1-5 cm spacing and thrust and strike-slip fault. By the drilling core of this area, most RQD have 0-20%.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.271-278
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• 2012

In this work, we have prepared the nanocomposite by the reaction of mica and zinc oxide, and investigated the application of nanocomposite to UV protecting creams. Mica treated with 3-aminopropyltrimethoxysilane (APTMS) reacted with 1,4-phenylenediisothiocyanate (PDC) to give -N=C=S functionalized surface, which was further reacted with zinc oxides coated with APTMS to give mica-zinc oxide nanocomposites. The composites were characterized by EA, EDS, TGA, SEM, zeta potential measurement, powder XRD, and DRS UV/Vis analyses. Finally, we measured transmittances of ultraviolet protection creams manufactured by using mica composite covered with zinc oxides in the range of 280~400 nm. The nanocomposites developed in this work might be applicable as inorganic hybrid materials for UV protecting creams.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.51-58
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• 1998

Generally pigment differs from dye stuff because it cannot be melted in water but also because it is stable physically and chemically. In this study you will discover the function, properties and effects of Micai-TiO$_2$-SiO$_2$pigment as abase material pigment. But until now used Mica of the base material is about 7-l5${\mu}{\textrm}{m}$ with an average diameters of 15${\mu}{\textrm}{m}$. A new characteristic superficial pigment was obtained from covering the TiO$_2$ and SiO$_2$ with the adsorption result of isoelectric point of a Mica flake, TiO$_2$ and SiO$_2$In the composition reaction study of adsorption was done as well as the physical characteristics of the superficial texture of the obtained material. L,a,b of color change as oil was absorbed, optical nature and change of reflection according to direct and diffused reflection. In the composition of Mica slurry the best result obtained was in a solution with pH 2.0 to 2.3. Following this result, we can come to the idea that electrical attraction was done during the change of electrical charge of the Mica and TiO$_2$ deposit. Also this pigment shows a big scale between the direct reflection and diffused reflection light. Using this characteristic in cosmetic, it was obtained a natural but a contrast between light and shadow making possible a sculptured make-up. Color change due to oil adsorption was insignificant which improved the last of make up.

• Journal of the Korean Ceramic Society
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• v.20 no.1
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• pp.37-42
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• 1983

An attempt was made to derive a possible synthetic mechanism of Fluoro-phlogopite (Mica, 4Mg.$Al_2O_3$.$6SiO_2$.$K_2O$.$2MgF_2$) The pevention of fluorine vaporization turned out to be the key in the synthesis of Mica in question.l Consequently the quinary system of Mica was seperately synthesized ; frist 4MgO.$Al_2O_3-6SiO_2$(ternary system) was sintered at 135$0^{\circ}C$ and $K_2O$ and $MgF_2$ were added and second 4MgO.$Al_2O_3-6SiO_2$.$K_2O$ (quarternary system) was heat-treated at 135$0^{\circ}C$ and $MgF_2$ was added. The ternary system resulted in Proto-enstatite Cordierite and Spinel phases while Forsterite and Leucite were shown in the quarternay system . In both methods Fluoro-phlogopite was systhesized but the solid state reactions to form Mica from the ternary system and the quarternary system were different. High temperature reactions in the formation of Mica were investigated employing XRD, DTA and SEM The study of the synthesis of Mica indirectly suggested a method of phase analysis of quinary system(MgO-$Al_2O_3-SiO_2-K_2O-MgF_2$) and quarternary system(MgO-$Al_2O_3-SiO_2-K_2O-MgF_2$) at various temperatures.