• Journal of the Mineralogical Society of Korea
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• v.6 no.1
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• pp.17-26
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• 1993

Mineralogical characteristics of tosudite from the Sungsan and Bubson mines were studied and correlated using X-ray diffraction analysis, chemical analysis and electron microscopy. Tosudite occurs as an alteration product of Cretaceous volcanoclastic rocks in both mines. It is associated with microcrystalline quartz, dickite, illite/smectite or mica/smectite mixed-layer mineral. It forms cryptocrystalline aggregates with flaky habit. XRD analysis suggests that tosudite is an 1:1regularly interstratified dioctahedral smetite/dioctahedral chlorite. Bubsoo tosudite has more(00ℓ ) reflections and more periodice stacking sequence than Syngsan tosudite. Chemical analysis shows that tosudite is a Li-bearing aluminous 1:1 regularly interstrattified mineral composed of K-bedellite and donbassite. Cookeite component may be present in the chlorite layer. Bubsoo tosudite is more Al in tetrahedral site and Ca in interlayer, but less Al in octahedral site than Sugsan tosudite. Tosudite may be formed as the intermediate alteration products, forming after muscovite and before illite/smectite or mica/s$^{\circ}C$mectite, with the range from 100 $^{\circ}C$ to 360 ~ 480 $^{\circ}C$. The hydrothermal solution forming tosudite may be acidic solution with high activities of Si and Al.

• Journal of the Mineralogical Society of Korea
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• v.28 no.4
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• pp.325-332
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• 2015

Apophyllite (KF)($K_{0.84}Ca_{3.99}Si_{7.70}O_{20}F_{0.72}{\cdot}8H_2O$), one of the sheet silicates, was compressed up to 7.7 GPa at ambient temperature and 15 high pressure data were obtained. Lattice parameters of the starting specimen were as follows: $a_0=8.954(2)\;{\AA}$, $c_0=15.795(2)\;{\AA}$, $V_0=1266.4(4)\;{\AA}^3$. Symmetrical diamond anvil cell was employed with synchrotron radiation in the mode of angular dispersive X-ray diffraction. Bulk modulus was determined to be 59(4) GPa when ${K_0}^{\prime}$ is 4. No clear first order phase transition symptom was observed in the series of XRD pattern. However, second-order phase transition cannot be ruled out from the correlation between normalized pressure and strain.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.608-614
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• 2009

In this work, ruthenium substituted SBA-15's(Ru-SBA15's) of various Si/Ru ratios were prepared using a non-ionic triblock copolymer surfactant, $EO_{20}PO_{70}EO_{20}$, as template. We investigated the nitrogen or oxygen adsorption/desorption behaviors of the Ru-SBA-15's for their future applications as catalysts or selective adsorbents, etc. The pore size of the Ru-SBA-15's was determined by both the Barrett-Joyner-Halenda(BJH)($D_{BJH}$) and the Broekhoff-de Boer analysis with a Frenkel-Halsey-Hill isotherm(BdB-FFF) method($D_{BdB-FHH}$). The $D_{BJH}$ and $D_{BdB-FHH}$ of the Ru-SBA-15 having 50/1 ratio of Si/Ru were 3.9 nm and 4.7 nm, respectively. The transmission electron microscope(TEM) image of the Ru-SBA 15 of the Si/Ru mole ratio of 50 showed that the pore size is 4.7 nm, which is consistent with the $N_2$ adsorption results with the BdB-FHH method. The surface area of pores form oxygen adsorption/desorption isotherm was higher than that from the nitrogen adsorption/desorption isotherm by the Brunauer-Emmett-Teller(BET) method, which were respectively $612.7m^2/g$, and $573.3m^2/g$. X-ray diffraction(XRD) patterns and TEM analyses showed that the mesoporous materials possess well-ordered hexagonal arrays.

• Journal of the Mineralogical Society of Korea
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• v.29 no.1
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• pp.23-34
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• 2016

Tsogttsetsii area, an intrusive complex associated with Cu porphyry mineralization, is located in the Gurvansaikhan island arc terrane of the Central Asian Orogenic belt, Southern Mongolia. We performed a reconnaissance survey in Tsogttsetsii area. Cu mineralization in Tsogttsetsii area is porphyry Cu type related with alkali granite intruded in Permian. Mineralogical and textural properties of the ores and associated minerals were analyzed using X-ray diffraction, thin section petrography, and Scanning electron microscopy-Energy dispersive spectroscopy (SEM-EDS). Ore minerals identified in polarizing microscope are magnetite, pyrite and bornite. Propylitic alteration zone occurs broadly in the area where malachite occurrences are shown to be spread intensively in alkali granite area. Quartz, sericite, chlorite and epidote were observed in the alteration zone samples. As results of XRD and SEM-EDS analysis, samples of copper oxides were composed mainly of malachite, cuprite and small amounts of quartz. Average and maximum Cu contents of samples collected from malachite occurrences area are 759 ppm and 6190 ppm, respectively. The characteristics of mineralization in Tsogttsetsii area is similar to Oyu Tolgoi Cu-Au (Mo) deposit and Tsagaan Suvarga Cu-Mo deposit which are 56 km south and 120 km northeast from Tsogttsetsii area, respectively. Characteristics of the study area, such as the geology, tectonic environment, lithology, mineralization, and alterations of the rocks within the survey area, resemble the characteristics of other porphyry deposits. Therefore further exploration including Induced Polarization (IP) survey for identifying subsurface orebody is required.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.195-202
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• 2013

$TiO_2$ powders were prepared from titanium (IV) sulfate ($Ti(SO_4)_2$) solution using ammonia solution at low reaction temperature ($80{\sim}100^{\circ}C$) and atmospheric pressure by hydrothermal precipitation method without calcination. The effect of reaction conditions, such as reaction temperature, initial concentration of titanium (IV) sulfate ($Ti(SO_4)_2$) solution, pH of mixture solution and the physical properties of the prepared $TiO_2$, such as crystallite structure, crystallite size were investigated. The photocatalytic activity of prepared $TiO_2$ was tested by the photolysis of brilliant blue FCF (BB-FCF) under the UV and the analysis of UV-VIS diffuse reflectance spectroscopy (DRS). The physical properties of prepared $TiO_2$ were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectrometer (PL), particle size distribution measurements. The crystallite size and crystallinity of prepared $TiO_2$ increased with increasing titanium (IV) sulfate ($Ti(SO_4)_2$) concentration, but photocatalytic activity decreased. The crystallite size decreased with increasing pH of mixture solution, but photocatalytic activity increased. The crystallinity and photocatalytic activity increased with increasing reaction temperature. The results showed that anatase type $TiO_2$ could be prepared by hydrothermal precipitation method using titanium (IV) sulfate ($Ti(SO_4)_2$) solution and ammonia solution at low reaction temperature and atmospheric pressure without calcination.

• Clean Technology
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• v.21 no.3
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• pp.153-163
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• 2015

The effects of H₂O and residue SO₂ in flue gases on the activity of the Fe/zeolite catalysts for low-temperature NH₃-SCR of NO were investigated. And the addition effect of Mn, Zr and Ce to Fe/zeolite for low-temperature NH₃-SCR of NO in the presence of H₂O and SO₂ was investigated. Fe/zeolite catalysts were prepared by liquid ion exchange and promoted Fe/zeolite catatysts were prepared by liquid ion exchange and doping of Mn, Zr and Ce by incipient wetness impregnation. Zeolite NH₄-BEA and NH₄-ZSM-5 were used to adapt the SCR technology for mobile diesel engines. The catalysts were characterized by BET, X-ray diffraction (XRD), SEM/EDS, TEM/EDS. The NO conversion at 200 ℃ over Fe/BEA decreased from 77% to 47% owing to the presence of 5% H₂O and 100 ppm SO₂ in the flue gas. The Mn promoted MnFe/BEA catalyst exhibited NO conversion higher than 53% at 200 ℃ and superior to that of Fe/BEA in the presence of H₂O and SO₂. The addition of Mn increased the Fe dispersion and prevented Fe aggregation. The promoting effect of Mn was higher than Zr and Ce. Fe/BEA catalyst exhibited good activity in comparison with Fe/ZSM-5 catalyst at low temperature below 250 ℃.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.3
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• pp.45-50
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• 2015

The goal of this research is the create novel magnets with no rare-earth contents, with larger energy product by comparison with currently used ferrites. For this purpose we developed nano-sized hard-type/soft-type composite ferrite in which high remanent magnetization (Mr) and high coercivity (Hc). Nano-sized Ba-ferrite, Ni-Zn ferrite and $BaFe_{12}O_{19}/Ni_{0.5}Zn_{0.5}Fe_2O_4$ composite ferrites were prepared by sol-gel combustion method by use of glicine-nitrate and citric acid. Nanocomposite ferrites were calcined at temperature range $700-900^{\circ}C$ for 1h. According to the X-ray diffraction patterns and FT-IR spectra, single phase of NiZn-ferrite and Ba-ferrite were detected and hard/soft nanocomposite ferrite was indicated to the coexistence of the magnetoplumbite-structural $BaFe_{12}O_{19}$ and spinel-structural $Ni_{0.5}Zn_{0.5}Fe_2O_4$ that agreed with the standard JCPDS 10-0325 data. The particle size of nanocomposite turn out to be less than 120 nm. The nanocomposite ferrite shows a single-phase magnetization behavior, implying that the hard magnetic phase and soft magnetic phase were well exchange-coupled. The specific saturation magnetization ($M_s$) of the nanocomposite ferrite is located between hard ($BaFe_{12}O_{19}$) and soft ferrite($Ni_{0.5}Zn_{0.5}Fe_2O_4$). The remanence (Mr) of nanocomposite ferrite is much higher than that of the individual $BaFe_{12}O_{19}$ and $Ni_{0.5}Zn_{0.5}Fe_2O_4$ ferrite, and $(BH)_{max}$ is increased slightly.

• Korean Journal of Food Science and Technology
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• v.48 no.2
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• pp.165-171
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• 2016

Physicochemical properties of waxy maize flours prepared by hydrothermal and enzymatic treatments were evaluated. Waxy maize flours were hydrothermally treated using heat-moisture treatment (HMT) and annealing (ANN) and enzymatically treated using commercial enzymes (cellulase, proteinase, and pectinase). The HMT-modified waxy maize flours had low water absorption index (WAI), melting enthalpy, viscosity, and crystallinity. However, ANN-modified and enzymatically modified waxy maize flours had high WAI, melting enthalpy, and viscosity. X-ray diffraction analysis of ANN-modified and enzymatically modified waxy maize flours revealed a typical A-type pattern and displayed sharper crystalline peaks than those observed for the control groups (native waxy maize flours). In contrast, the crystallinity of HMT-modified waxy maize flours were decreased by hydrothermal treatment.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.2
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• pp.89-93
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• 2017

GaN single crystals were grown by controlling of various processing parameters such as growing temperature, V/III ratio and growing rate. We optimized thickness of bulk GaN single crystal by analyzing defect of surface and inside of the GaN single crystal for application to high brightness and power device. 2-inch bulk GaN single crystals were grown by HVPE (hydride vapor phase epitaxy) on sapphire and their thickness was 0.3~7.0 mm. Crystal structure of the grown bulk GaN was analyzed by XRD (X-ray diffraction). The surface characteristics of the grown bulk GaN were observed by OM (optical microscope) and SEM (scanning electron microscopy) with measuring EPD (etch pits density) of the GaN crystals.

• Polymer(Korea)
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• v.34 no.3
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• pp.269-273
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• 2010

The primary objective of this work is to find the optimal condition for the granule tablet formulation of alfuzosin-HCl that aims to achieve a sustained drug release. (Hydroxypropyl)methyl cellulose (HPMC) is one of the most widely used polymer as a drug formulation and therefore has been utilized in this study as an excipient. Alfuzosin-HCl granule tablet was developed using the various viscosities of HPMC and the effects of viscosity on drug release was investigated. Fourier transform-infrared (FTIR) and X-ray diffraction (XRD) were employed to investigate the chemical structure and crystallization of alfuzosin-HCl in the formulation. We prepared the granule tablet by a direct compression method and studied the release profile in the stimulated intestinal fluid (pH 6.8). As the viscosity of HPMC increased the release of alfuzosin-HCl decreased, demonstrating that controlled release of alfuzosin-HCl can be achieved by varying the viscosity of HPMC.