• Journal of Environmental Science International
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• v.28 no.6
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• pp.553-559
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• 2019

In this study, zeolitic materials at $Na_2CO_3/CFA$ ratio of 0.6 - 1.8 were synthesized from coal fly ash from a thermal power plant using a fusion/hydrothermal method. The zeolitic materials were found to have cubic crystals structure and X-ray diffraction (XRD) peaks of Na-A zeolite by XRD and SEM analysis. When the zeolitic materials were synthesized from the coal fly ash, the XRD peaks of the zeolitic materials at $Na_2CO_3/CFA$ ratios of 0.9-1.8 had the same location as the XRD peaks of commercial Na-A zeolite. The XRD peaks of the Na-A zeolite ($Na_{12}Al_{12}Si_{12}O_{48}27.4H_2O$) were confirmed in the $2{\theta}$ in the range of 7.18-34.18. However, it was also confirmed that peaks of $CaCO_3$, an impurity inhibiting synthesis of Na-A zeolite from CaO and $Na_2CO_3$ in the coal fly ash, occurred in the XRD peaks of the zeolitic materials at $Na_2CO_3/CFA$ ratio of 1.5-1.8. The crystallinities of the zeolitic materials tended to increase gradually within the $Na_2CO_3/CFA$ ratio range of 0.6-1.8.

• Membrane and Water Treatment
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• v.13 no.4
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• pp.183-189
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• 2022

This study seeks towards an optimal way to control sulfate ions in semiconductor wastewater effluent with potential eco-toxicity. We developed a system based on ettringite (Ca₆Al₂(SO₄)₃(OH)₁₂·26H₂O). The basic idea is that the pH of the water is raised to approximately 12 with Ca(OH)₂. After, aluminium salt is added, leading to the precipitation of ettringite. Lab-scale batch and continuous experiment results with real semiconductor wastewater demonstrated that 1.5 and 1 of stoichiometric quantities for Ca²⁺ and A³⁺ with pH above 12.7 could be considered as the optimal operation condition with 15% of sludge recycle to the influent. A mixed AlCl₃ + Fe reagent was selected as the beneficial Al³⁺ source in ettringite process, which resulted in 80% of sludge volume reduction and improved sludge dewaterability. The results of continuous experiment showed that with precipitation as ettringite, sulfate concentration can be stably reduced to less than 50 mg/L in effluent from the influent 2,050 ± 175 mg/L on average (1,705 ~ 2,633 mg/L).

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.310-315
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• 2019

This study conducted a series of studies to find alternative ways to use Chlorine Bypass System-dust(CBS-dust) in cement production. The results of engineering characteristics of CBS-dust are summarized as follows. First of all, the density of CBS-dust is 2.40, lighter than cement and the pH was 12.50 which was strong alkaline. In terms of particle size, it was 11.70 ㎛ which was finer than cement. With chemical properties, calcium oxide(CaO) was the highest as 35.10%, potassium oxide(K₂O) was 32.43%, potassium chloride(KCl) was 19.46%, sulfur oxide(SO₃) was 6.81%, and the remaining chemical components are SiO₂, Fe₂O₃, Al₂O₃, MgO, and the like. Therefore, if CBS-dust is used as early-strength chemical admixtures in the concrete secondary products that use a large amount of mineral admixtures without rebar, it can be an effective method for increasing the strength of concrete as an alkali activator and preventing early-frost damage of Cold Weather Concrete.

• Proceedings of the Korean Vacuum Society Conference
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• 2007.08a
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• pp.98-98
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• 2007

• Korean Journal of Mineralogy and Petrology
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• v.35 no.2
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• pp.153-168
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• 2022

Petrological and mineralogical analyses were conducted to identify minerals containing radioactive elements (uranium) in the Chiaksan gneiss complex and to confirm their association with the surrounding groundwater. Fourteen minerals were identified through the microscopic and electron microscopy (SEMEDS) investigation. The principal minerals included plagioclase, biotite, quartz, alkali feldspar, chlorite, and calcite. Minor minerals were sphene, allanite, apatite, zircon, thorite, titanite, pyrite, and galena. A small amount of thorite was observed in the size of ~1 mm within macrocrystalline allanite. Allanite, which includes a large amount of rare earth elements, appeared in three distinctive patterns. The results of the EPMA analyses indicated that macrocrystalline allanite had higher elemental contents of TiO₂~1.70 wt.%, Ce₂O₃~11.86 wt.%, FeO ~13.31 wt.%, MgO ~0.90 wt.% and ThO₂ ~1.06 wt.% with the lowest average content of Al₂O₃ 17.35 ± 2.15 wt.% (n = 7), CaO 12.13 ± 1.81 wt.% (n = 7). An allanite existing at the edge of the sphenes encompassing titanites had a higher element content of Al₂O₃ ~24.00 wt.%, Nd₂O₃ ~5.10 wt.%, Sm₂O₃~0.66 wt.%, Dy₂O₃~0.86 wt.% and Y₂O₃~1.38 wt.% with the lowest average content of TiO₂ 0.35 ± 0.21 wt.% (n = 11), Ce₂O₃ 5.25 ± 1.03 wt.% (n = 11), FeO 9.84 ± 0.26 wt.% (n = 11), MgO 0.12 ± 0.05 wt.% (n = 11), and La₂O₃ 1.49 ± 0.29 wt.% (n = 11). Allanites in a matrix of parental rocks exhibited intermediate values between the two elemental compositions mentioned above. None of the uranium-rich minerals were observed in the migmatitic gneiss within the study area. Consequently, the origin of uranium in the groundwater was not associated with the geology of the surrounding environment, but our investigation proved the existence of abundant allanites containing significant amounts of radioactive thorium and rare earth elements.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.12
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• pp.755-760
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• 1999

Various fluoride films were investigated for a gate insulator of thin film transistor application. Conventional oxide containing materials like $SiO_2\;Ta_2O_5\; and \; Al_2O_3$ exhibited high interface states which lead to an increased threshold voltage and poor stability of TFT. In this paper, we investigated gate insulators using a binary matrix system of fluoride such as $CaF_2,\; SrF_2\; MgF_2,\; and\; BaF_2$. These materials exhibited an improvement in lattice mismatch, interface state and electrical stability. MIM and MIS devices were employed for an electrical characterization and structural property examination. Among the various fluoride materials, $CaF_2$ film showed an excellent lattice mismatch of 5%, breakdown electric field higher than 1.2MV/cm and leakage current density of $10^{-7}A/cm^2$. MIS diode having $Ca_2$ film as an insulation layer exhibited the interface states as low as $1.58\times10^{11}cm^{-2}eV^{-1}$. This paper probes a possibility of new gate insulator materials for TFT applications.

• Economic and Environmental Geology
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• v.30 no.1
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• pp.35-49
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• 1997

The coal formation of the Deokpyeong area are interbedded along metapelites of the Ogcheon Supergroup, which are composed mainly of graphite, quartz, muscovite and associated with small amounts of biotite, chlorite, pyrite and barite. The ratios of $SiO_2/Al_2O_3$, $Al_2O_3/Na_2O$ and $K_2O/Na_2O$ of the coaly metapelite are variable and wide range from 1.80 to 10.21, from 27.8 to 388.8 and from 7.6 to 61.8, respectively. These coal formation were deposited in basin of marine environments, and the REE of these rocks are not influenced with metamorphism and hydrothermal alterations on the basis of $Al_2O_3$ versus La, La against Ce, the ratios of La/Ce (0.19 to 0.99) and Th/U (0.02 to 4.75). These rocks also show much variation in $La_N/Yb_N$ (1.19 to 22.89), Th/Yb (0.14 to 21.43) and La/Th (0.44 to 13.67), and their origin is explained by derivation from a mixture of sedimentary and igneous rocks. The wide range in trace and REE element characteristics as Co/Th (0.12 to 2.78), La/Sc (0.33 to 10.18), Sc/Th (0.57 to 5.73), V/Ni (8 to 2347), Cr/V (0.02 to 0.67) and Ni/Co (1.56 to 32.95) of these coaly metapelites argues for inefficient mixing of the various source lithologies during sedimentation. Deep to pale green barium-vanadium muscovites (vanadium-oellacherite) have been found in this coal formations. Modes of occurrence and grain size of muscovite are heterogeneous, but most of the barium and vanadium-bearing muscovites occur along the boundaries between graphite and quartz grains, ranging from 200 to $350{\mu}m$ in length and from 40 to $60{\mu}m$ in width. Results of X-ray diffraction data of the minerals characterized to be monoclinic system with $a=5.249{\AA}$, $b=8.939{\AA}$, $c=20.924{\AA}$ and ${\beta}=95.894^{\circ}$. Representative chemical formula of the muscovite was $(Na_{0.09}K_{1.44}Ba_{0.46})(Al_{2.75}Ti_{0.07}V_{0.56}Fe_{0.08}Mg_{0.50})(Si_{6.12}Al_{1.88})O_{22}$. The V possibly substitute octahedral Al, and the Ba is coupled substitution of $K^+Si^{4+}=Ba^{2+}Na^+Ca^{2+}$, which compositional ranges of V and Ba are from 0.42 to 0.69 and from 0.34 to 0.56 based on $O_{22}$, respectively. Formation mechanism of the barium-vanadium muscovites in the coaly metapelite is shown that the formed by high pressure and temperature from regional metamorphism origanated during diagenesis at the interface between a basinal brine and organic matter.

• Journal of the Korean Ceramic Society
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• v.34 no.7
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• pp.693-698
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• 1997

The refractive index and dispersion in the (100-x)(0.6CaO.0.4Al2O3).xSiO2(x=0~30) glasses were investigated. As the amount of SiO2 increased, the refractive index decreased. The change of refractive index was attributed to the change of the molar refraction rather than the molar volume. When the amount of SiO2 was smaller than 20 mol%, the average electronic transition energy gaps(E0) and the electronic oscillator strengths(Ed) were about 10.9($\pm$0.1) nd 18($\pm$0.5)eV, respectively. However E0 and Ed of the glass (CAS30) with 30 mol% SiO2 increased to 12.63 and 19.89eV, respectively. The similar results was observed in the variation of Abbe Number. Abbe number of the glass in the range of 0~20 mol% SiO2 was about 46 and that of CAS30 increased to 60. The zero-material dispersion wavelength({{{{ lambda }}0) of pure calcium aluminate glass was 1.8 ${\mu}{\textrm}{m}$. As the amount of SiO2 increased, the zero-material dispersion wavelength shifted to a shorter wavelength. {{{{ lambda }}0 of CAS30 was 1.5 ${\mu}{\textrm}{m}$, that is currently using for the optical telecommunication system.

• The Journal of the Petrological Society of Korea
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• v.4 no.2
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• pp.104-123
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• 1995

Mantle xenoliths in alkali basalt from Boun, Gansung area, and Baegryung island in S. Korea are spinel lherzolites composed of olivine, orthopyroxene, clinopyroxene, and spinel. The xenoliths generally show triple junctions among grams, kink-banding in olivine and pyroxenes, and protogranular and eqigranular textures having m orlentatron of specific direction. Anhedral brown spinels are disseminated in the intergranular spaces of minerals. Mineral compositions are very homogeneous without compositional zonation from rim to core in grains regardless different locahties. Olivine shows Fo. component of 89.0-90.2 and low CaO of 0.03-0.12wt%, orthopyroxene is enstatite with En component of 89.0 - 90.0 and $Al_2O_3$ of 4-5wt%, and clinopyroxene is diopside having En. component of 47.2-49.1 and $Al_2O_3$ of 7.42-7.64wt% from Boun and 4.70-4.91wt% from Baegryung showing local variation. Spinel shows the distinctive negative trend with increasing of A1 and decreasing of Cr, and Mg value and Cr number are 75.1-81.9 and 8.5-12.6, respectively. To estlmate T and P for these mantle xenoliths pyroxene-geothermometers (Wood and Banno, 1973; Wells, 1977; Mercier, 1980; Sachtleben and Seck, 1981; Bertrand and Mercier, 1985; Brey and Kohler, 1990) and Al-solubility geobarometer (Mercier, 1980; Lane and Ganguly, 1980) are used. Temperatures of Mercier (1980) and Sachtleben and Seck (1981) are compatible and equilibrium temperatures of xenoliths, average value of these two, aiie from $970^{\circ}C$ to $1020^{\circ}C$, and equihbrium pressures derived from Mercier (1980) are in the range of 12-19 Kb (42-63 Km). These temperatures and pressures seem to be reasonble wlth the consideration of Al-isopleths in MAS system (Lane and Ganguly, 1980) and Fe effect on Al-solubility in orthopyroxene (Lee and Ganguly, 1988). Equllibrium of temperatures and pressures of xenoliths in P-T space belong to ocenanic geothem among the Mercier's mantle geotherms (1980) and are completely different from continental geotherms of S. Africa (Lesotho) and S. India having different geologcal ages. anera1 compositions of spmel-lherzohtes in S. Korea and eastern China are primitwe and paleogeothems of both are very s~mllar, but degrees of depletion of upper mantle could be locally different from each other since eastern China has various depleted xenoliths due to different degrees of partial melting.

• Journal of the Speleological Society of Korea
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• v.45 no.46
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• pp.9-31
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• 1996

The Mt. Peakdu is situated in north of the main peninsula, commanding geographically coordinated between longitude W($127^{\circ}$ 15' - $128^{\circ}$ 00') to E($128^{\circ}$ 15'- $129^{\circ}$ 00'), between latitude from S($41^{\circ}$ 15'- $42^{\circ}$ 00') to N($42^{\circ}$ 10'- $42^{\circ}$ 40'). The Manjyang-Gul in Cheju volcanic island is situated in the south of the main peninsula, commanding the Korean Strait, geographically coordinated longitude N($33^{\circ}$ 32' 26") and E($126^{\circ}$ 46' 48"). The quantitative analysis using XRF of volcanic rock samples for the north of Lu- Ming- Feng in Mt. Peakdu Group and the Manjang-Gul in Cheju island was Performed. The major chemical components by group analysis are as follows; Peakdu-Mt. Cheju Peakdu-Mt. Cheju (1) $Na_2O$(3.29Wt% and 3.27Wt%) (2) MgO (3.95Wt% and 6.l5Wt%) (3) $Al_2O_3$((17.64Wt% and 15.l7Wt%) (4) $SiO_2$((50.62Wt% and 50.99Wt%) (5) $P_2O_5$ (0.36Wt% and 0.30Wt%) (6) $K_2O$ (1.37Wt% and 1.04Wt%) (7) CaO (8.56Wt% and 8.06Wt%) (8) $TiO_2$ (2.37Wt% and 2.l5Wt%) (9) MnO (0.llWt% and 0.l6Wt%) (10) $Fe_2O_3$(9.l2Wt% and 12.56Wt%) The Group analysis data were compared in the relation within the age of formation for $0.16{\pm}0.08Ma$ in Mt. Peakdu Group, and $0.42{\pm}42Ma$ or $0.42{\pm}42Ma$ in Cheju island for K-Ar age. The crystal structure are mixed crystal of monoclinic, hexagonal and triclinic system in Mt. Peakdu Group and mixed structure of triclinic and cubic system in Cheju volcanic island.ic island.