• Journal of the Mineralogical Society of Korea
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• v.6 no.2
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• pp.122-144
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• 1993

The Kimhae napseok clay deposit was studied to characterize its mineralogy and genesis. Geology of the deposit is composed of Tertiary volcanic rocks and granodiorite. Tertiary volcanic rocks consist of andesitic tuff with minor interstratified tuffaceous shale, and rhyodacitic tuff. The main ore body of 2.4 to 4 m in thickness developed parallel to the bedding of andesitic tuff bed. Its strike and dip are $N70^{\circ}E-N85^{\circ}E$ and $16^{\circ}NW-32^{\circ}NW$, respectively. Two alteration zones; the propylitic zone of albite-epidote-chlorite-quartz assemblage and advanced argillic zone of pyrophyllite-dickite-alunite-diaspore assemblage are developed. Correlation of $SiO_2$ to $Al_2O_3$ shows no relation in propylitic zone, while a negative linear relation in advanced argillic zone. Chemical variation shows that $SiO_2$, $Al_2O_3$, MgO, CaO, $Na_2O$ and $K_2O$ were leached out during hydrothermal alteration. Pyrophyllite, the most abundant mineral in advanced argillic zone, occurs as low temperature 2M polytype. It is closely associated with dickite, diaspore and alunite. The Hinckley index of dickite is 0.83 showing moderate crystallinity. Na content is increasing in the M site with the increasing content of cations in the R-site. the mole percent of Na replacing K in alunite ranges from 53.2 to 71.6. It is also found that pyrophyllite grows in the dissolution site of diaspore. Plagioclase was albitized. Lowering of pH caused mainly by sulfide and sulfate decomposition resulted in preferential leaching of Si. It is inferred that aluminum released from plagioclase in the volcanic rocks as well as from the tuffaceous shale intercalated in andesitic tuff were the main sources of aluminum required for the formation of clay deposit. pH in hydrothermal fluid decreased from propylitic zone to advanced argillic zone with increasing degree of alteration. Based on experimental data reported in the literature and mineral assemblages, the formation temperature of the deposit ranges 270 to $320^{\circ}C$.

• The Journal of the Petrological Society of Korea
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• v.4 no.1
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• pp.31-48
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• 1995

The Jurassic Kwanaksan stock, so far known to be composed of biotite granite only, has the mineral assemblage of quartz+K-feldspar+plagioclase+biotite${\pm}$gernet. The lithology of the stock is classified as alkali feldspar granite by their mode and plagioclase compositions (An<5). Subsolvus feldspars, rather early crystallization of biotite, and shallow emplacement depth estimated from Q-Ab-Or diagram suggest hydrous nature of the magma, which contrasts with anhydrous A-type like geochemistry described below. Major and trace element compositions of the Kwanaksan stock are distinct from those of the adjacent Seoul batholith, suggesting a genetic difference between the two, The Kwanaksan stock shows geochemical characteristics similar to A-type granite in contrast to most other Mesozoic granites in Korea, in that it has high $SiO_2$(73~78wt%), $Na_2O+K_2O$, Ga(27~47 ppm). Nb(22~40 ppm), Y(48~95 ppm), Fe/Mg and Ga/Al, and low CaO(<0.51 wt%). Ba (8~75 ppm) and Sr(2~23 ppm). However, it has lower Zr and LREE and higher Rb(384~796 ppm) than typical A-type granite. LREE-depleted rare earth element pattern with strong negative Eu anomaly of previous studies is reinterpreted as representing source magma characteristics. The residual material during partial melting is not compatible with pyroxenes, amphibole or garnet, while significant amount of plagioclase is required. Similarity of geochemistry of the Kwanaksan stock to A-type granite suggests the origin of the stock has a chose relationship with that of A-type granite. These observations lead us to propose that the Kwanaksan stock was formed by partial melting of felsic source rock.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.1
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• pp.40-46
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• 2013

The isotope ratios of $^{13}C/^{12}C$ and $^{18}O/^{16}O$ for a sample in a mass spectrometer are measured relative to those of a pure $CO_2$ reference gas (i.e., laboratory working standard). Thus, the calibration of a laboratory working standard gas to the international isotope scales (Pee Dee Belemnite (PDB) for ${\delta}^{13}C$ and Vienna Standard Mean Ocean Water (V-SMOW) for ${\delta}^{18}O$) is essential for comparisons between data sets obtained by other groups on other mass spectrometers. However, one often finds difficulties in getting well-calibrated standard gases, because of their production time and high price. Additional difficulty is that fractionation processes can occur inside the gas cylinder most likely due to pressure drop in long-term use. Therefore, studies on laboratory production of pure $CO_2$ isotope standard gas from stable solid calcium carbonate standard materials, have been performed. For this study, we propose a method to extract pure $CO_2$ gas without isotope fractionation from a solid calcium carbonate material. The method is similar to that suggested by Coplen et al., (1983), but is better optimized particularly to make a large amount of pure $CO_2$ gas from calcium carbonate material. The $CaCO_3$ releases $CO_2$ in reaction with 100% pure phosphoric acid at $25^{\circ}C$ in a custom designed, evacuated reaction vessel. Here we introduce optimal procedure, reaction conditions, and samples/reactants size for calcium carbonate-phosphoric acid reaction and also provide the details for extracting, purifying and collecting $CO_2$ gas out of the reaction vessel. The measurements for ${\delta}^{18}O$ and ${\delta}^{13}C$ of $CO_2$ were performed at Seoul National University using a stable isotope ratio mass spectrometer (VG Isotech, SIRA Series II) operated in dual-inlet mode. The entire analysis precisions for ${\delta}^{18}O$ and ${\delta}^{13}C$ were evaluated based on the standard deviations of multiple measurements on 15 separate samples of purified $CO_2$. The pure $CO_2$ samples were taken from 100-mg aliquots of a solid calcium carbonate (Solenhofen-ori $CaCO_3$) during 8-day experimental period. The multiple measurements yielded the $1{\sigma}$ precisions of ${\pm}0.01$‰ for ${\delta}^{13}C$ and ${\pm}0.05$‰ for ${\delta}^{18}O$, comparable to the internal instrumental precisions of SIRA. Therefore, we conclude the method proposed in this study can serve as a way to produce an accurate secondary and/or laboratory $CO_2$ standard gas. We hope this study helps resolve difficulties in placing a laboratory working standard onto the international isotope scales and does make accurate comparisons with other data sets from other groups.

• Journal of Environmental Health Sciences
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• v.49 no.5
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• pp.251-261
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• 2023

Background: This paper deals with the study of natural radioactivity in rocks from Ogun State in Southwestern Nigeria. The aim is to determine radiation emissions from rocks in order to estimate radiation hazard indices. Objectives: The following objectives were targeted: 1. To determine radiation emissions from each type of rocks; 2. To estimate radiation hazard indices based on the rocks; 3. To correlate the activity concentrations of radionuclides with major oxides. Methods: The samples were analyzed using a NaI (Tl) gamma ray spectrometric detector and PerkinElmer AAnalyst 400 AAS spectrometer. Results: The activity of ⁴⁰K, ²²⁶Ra, and ²³²Th were found in order of decreasing magnitude from pegmatite>granite>migmatite. In contrast, lower concentrations were found in shale, phosphate, clay stone, sandstone and limestone. The mean absorbed doses were 125±23 nGyh^-1 (migmatite), 74±13 nGy/h (granite), 72±13 nGyh^-1 (pegmatite), 64±09 nGyh^-1 (quartzite), 45±16 nGyh^-1 (shale), 41±09 nGyh^-1 (limestone), 41±11 nGyh^-1 (clay stone), 24±03 nGyh^-1 (phosphate), and 21±10 nGyh^-1 (sandstone). The outdoor effective dose rates in all rock samples were slightly higher than the world average dose value of 0.34 mSvy^-1. The percentage composition of SiO₂ in the rock samples was above 50 wt% except for in the limestone, shale and phosphate. Al₂O₃ ranged from 4.10~21.24 wt%, Fe₂O₃ from 0.39~7.5 wt%, and CaO from 0.09-46.6 wt%. In addition, Na₂O and K₂O were present in at least 5 wt%. Other major oxides, including TiO₂, P₂O₅, K₂O, MnO, MgO and Na₂O were depleted. Conclusions: The findings suggest that Ogun State may be described as a region with elevated background radiation. It is recommended that houses should be constructed with good cross ventilation and residences should use home radiation monitoring instruments to monitor radon emanating from walls.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.4
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• pp.366-375
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• 2001

The objective of this study was to investigate the surface contact and screw joint stability between screw and implant interface by use of sealer. The implants evaluated in this study were Steri-Oss futures(Hexlock $3.8D{\times}10mm$: Steri-Oss, Yorba Linda, CA), and Steri-Oss staight abutment. Titanium alloy screws were used to secure abutments to implants. The other titanium alloy screws applicating sealer(Impla-Seal, Implant Support Systems, Inc. Irvine, CA) were used to secure abutments to implants. In one another sample, 6kg of force was applied during simulated intraoral movements after abutment screws were secured to the implants with sealer. All samples were cross sectioned with sandpaper and polished with $0.1{\mu}m\;Al_2O_3$. Then samples were recorded with an scanning electron microscope. The results were as follows : 1. In the case of titanium alloy screw, irregular contacts and relatively large gap were present at thread mating surface. Also abutment screw/implant interface demonstrate incomplete seating and only one surface contact of threads between implant and screw. 2. In the case of titanium alloy screw applecating sealer, sealer was present between implant and screw. Therefore implant and screw had relatively close and tight contact without the presence of large gap. 3. On the other hand, in the case of titanium alloy screw applicating sealer and dynamic loading of suprastructures, sealer was partially present between implant and screw. Conclusively, sealer fills voids, creating a barrier to moisture and bacteria. In addition, loading of suprastructures may change the situation and limit the indications for gap sealing.

• Journal of the Korean Chemical Society
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• v.66 no.2
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• pp.78-85
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• 2022

Natural white clay was treated with 6 M of H₂SO₄ and heated at 80℃ for 6 h under mechanical stirring and the resulting acid active clay was used as an adsorbent for the removal of Cs⁺ in water. The physicochemical changes of natural white clay and acid active clay were observed by X-ray Fluorescence Spectrometry (XRF), BET Surface Area Analyser and Energy Dispersive X-line Spectrometer (EDX). While activating natural white clay with acid, the part of Al₂O₃, CaO, MgO, SO₃ and Fe₂O₃ was dissolved firstly from the crystal lattice, which bring about the increase in the specific surface area and the pore volume as well as active sites. The specific surface area and the pore volume of acid active clay were roughly twice as high compared with natural white clay. The adsorption of Cs⁺ on acid active clay was increased rapidly within 1 min and reached equilibrium at 60 min. At 25 mg L^- of Cs⁺ concentration, 96.88% of adsorption capacity was accomplished by acid active clay. The adsorption data of Cs⁺ were fitted to the adsorption isotherm and kinetic models. It was found that Langmuir isotherm was described well to the adsorption behavior of Cs⁺ on acid active clay rather than Freundlich isotherm. For adsorption Cs⁺ on acid active clay, the Langmuir isotherm coefficients, Q, was found to be 10.52 mg g^-1. In acid active clay/water system, the pseudo-second-order kinetic model was more suitable for adsorption of Cs⁺ than the pseudo-first-order kinetic model owing to the higher correlation coefficient R² and the more proximity value of the experimental value q_e,exp and the calculated value q_e,cal. The overall results of study showed that acid active clay could be used as an efficient adsorbent for the removal of Cs⁺ from water.

• Journal of the Korean Magnetics Society
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• v.3 no.1
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• pp.23-28
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• 1993

Thin films of soft magnetic Fe-Hf-C alloys with nanoscale crystallites were investigated in this study. The films were fabricated by an RF diode magnetron sputtering apparatus and subsequently annealed in vacuum. The soft magnetic properties of the films were observed to differ depending on the different substrates such as Corning 7059, $CaTiO_3$ and $Al_2O_3-TiC$ with various underlayer(Cr, $SiO_2$) thickness. This results may be due to the interdiffusion between the substrate and the magnetic layer and/or between the underlayer and the magnetic layer, rather than the microstructural change such as grain size. The Fe-Hf-C films with high permeability up to 4000(at 1 MHz) and saturation magnetization up to 16 kG were obtained in the vicinity of phase boundary between the crystalline and amorphous state when the size of ${\alpha}-Fe$ grains is about 5 nm. And also the films were found to have thermal stability up to $600^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.381-386
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• 2010

Some basic properties of inorganic coatings hardened by the room temperature reaction with alkalies were examined. The coating paste was prepared from the powders in the system $Al_2O_3-SiO_2$-CaO using blast furnace slag, fly ash and amorphous ceramic fiber after mixing with a solution of sodium hydroxide and water glass. The mineralogical and morphological examinations were performed for the coatings prepared at room temperature and after heating to $1200^{\circ}C$ respectively. The binding force of the coating hardened at room temperature was caused by the formation of fairly dense matrix mainly composed of oyelite-containing amorphous phase formed by the reaction between blast furnace slag and alkali solution. At the temperature, fly ash and ceramic fiber was not reacted but imbedded in the binding phase, giving the fluidity to the paste and reinforcing the coating respectively. During heating up to $1200^{\circ}C$, instead of a break in the coating, anorthite and gehlenite was crystallized out by the reaction among the binding phase and unreacted components in ternary system. The crystallization of these minerals revealed to be a reason that the coating maintains dense morphology after heating. The maintenance of binding force after heat treatment is seemed to be also caused by the formation of welldispersed fiber-like mineral phase which is originated from the shape of the amorphous ceramic fiber used as a raw materials.

• Clean Technology
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• v.26 no.4
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• pp.304-310
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• 2020

In order to apply a photocatalyst (TiO2) to various building materials, TiO2-mayenite was prepared in this study. The TiO2 was synthesized using the sol-gel method by fixing titanium isopropoxide (TTIP) and urea at a ratio of 1 : 1. Later, they were calcined in a temperature range of 400-700 ℃ to analyze the properties according to temperature. BET, TGA, and XRD were used to analyze the physical and chemical properties of TiO2. The nitrogen oxide removal test was confirmed by measuring the change in the concentration of NO for 1 h according to KS L ISO 22197-1. The prepared TiO2 samples exhibited an anatase crystal structure below 600 ℃, and TiO2 (urea)-400 showed the highest nitrogen oxide removal rate at 2.35 µmol h-1. TiO2-mayenite was prepared using two methods: spraying TiO2 dispersion solution (s/s) and sol-gel solution (g/s). Through BET and XRD analysis, it was found that 5-TiO2 (g/s) prepared by spraying a sol-gel solution has maintained its crystallinity even after heat treatment. Also, 5-TiO2 (g/s)-500 showed the highest removal rate of 0.55 µmol h-1 in the nitrogen oxide removal test. To prepare TiO2-mayenite, it was confirmed that mayenite should be blended with TiO2 in a sol-gel state to maintain the crystal structure and exhibit a high nitrogen oxide removal rate.

• Journal of the Korean GEO-environmental Society
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• v.12 no.7
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• pp.23-29
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• 2011

The oxidation slag has been widely used in civil engineering project, whereas the reduced slag from electric furnace has yet to be applied. Consequently in order to find out the recycling method in civil engineering field, the mineral compositions of the reduced slag were analyzed and some tests on water quality were performed to estimate the potential release of toxic compounds. Slag-soil mixtures of 0, 10, 20 and 30%(dry weight) soil were prepared in lysimeter columns and the effluents were collected with the period of one, two and four week options in closed system, respectively. The result from qualitative and quantitative analysis using X-ray Diffraction(XRD) and X-ray Fluorescence(XRF) indicates that the main mineral of the reduced slag is $Ca_2(SiO_4)$, a kind of calcium silicate. Also, the leaching medium analyzed by Inductively Coupled Plasma Optical Emission Spectroscopy(ICP-OES) showed that main heavy metals such as Al, Fe and Mn are included in the reduced slag due to the effect of steel production process. It can be seen that the leachate does not violate the regulation guide line of waste material of heavy metal. Also the pH levels were increased from pH 6.9 for 0% soil to pH 10 for 30% soil. However the influence on leachate circulation period of one through four weeks was negligible.