• 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.

• Journal of the Korean institute of surface engineering
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• v.54 no.5
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• pp.238-247
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• 2021

PEO (plasma electrolytic oxidation) was applied to modify the surface of AZ31 magnesium alloy in this study. The mixed solution of sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) was used as the electrolyte, and 0 - 0.05 g/L of Ca-GP (Glycerol Phosphate Calcium salt) was added in the electrolyte as an additive. PEO treatment was conducted at a current density of 30mA/cm² for 5 minutes using a DC power supply. The surface properties were identified by SEM, XRD and surface roughness analyses, and the corrosion resistance was evaluated by potentiodynamic polarization and immersion tests. In addition, the biocompatibility was evaluated by immersion test in SBF solution. As the concentration of Ca-GP was increased, the surface morphology was denser and more uniform, and the amount of Ca and the thickness of oxide layer increased. Only Mg peak was observed in XRD analysis due to very thin oxide layer. The corrosion resistance of PEO-treated samples increased with the concentration of Ca-GP in comparision with the untreated sample. In particular, the highest corrosion resistance was identified at the group of 0.04g Ca-GP through potentiodynamic polarization and immersion tests in saline solution (0.9 wt.%NaCl). During the immersion in saline solution, pH rapidly increased at the beginning of immersion period due to rapid corrosion, and then increase rate of pH decreased. However, the pH value in the SBF temporarily increased from 7.4 to 8.5 during the day, then decreased due to the inhibition of corrosion with HA(hydroxyapatite) formation.

• The Journal of the Petrological Society of Korea
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• v.11 no.3_4
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• pp.200-213
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• 2002

The Andong granitoid batholith represents five temporally distinct episodes (phases) of igneous activity. The batholith represents a plutonic complex of five pulsatively emplaced distinct intrusive multiphases. The petrochemical data show that the plutons fall into calc-alkaline series except for the Yean pluton, and plot within the diaenostic range for I-type origin and continental arc orogenic tectonic setting. Each pluton reveals systematic compositional variations of major and trace elements with $SiO_2$ or MgO, but different variation trends for some elements and considerably different REE patterns. Thus discontinuous, inconsistent variations in the elements indicate that the five plutons can not be explained by simple fractional crystallization from the same primary magma, but were intruded and solidified from the independent magmas of chemically heterogeneous origin. In the Andong, Dosan and Pungsan plutons, high values of molar CaO/(MgO+$FeO^{t}$ ) combined with low $Al_2$$O_3$/(MgO+$FeO^{t}$ ) and $K_2$O$Na_2$O ratios suggest a magma originated by dehydration melting of a metabasaltic to metatonalitic protolith. Whereas the Imha pluton show similar values of CaO/(MgO+$FeO^{t}$ ), but significantly higher ratios of $Al_2$$O_3$/(MgO+$FeO^{t}$ ) and $K_2$O$Na_2$O implying to a metagreywacke protolith.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.799-816
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• 2023

Mineralogical and geochemical studies of shales within the Lower Anambra Basin was conducted to unravel the depositional environment, provenance, maturity, paleo-weathering conditions, and tectonic settings. Mineralogical studies conducted using X-ray diffraction analysis revealed that the samples were composed of kaolinite, montmorillonite, chlorite, and illite. KaolinIite is the dominant mineral, constituting approximately 41.5% of the bulk composition, whereas the non-clay minerals are quartz, ilmenite, and sillimanite. Geochemical analysis showed a predominance of SiO₂, Al₂O₃, and Fe₂O₃ contents of the shale samples with mean values of 52.29%, 14.09%, and 6.15% for Imo Shale (IS); 52.31%, 16.70%, and 7.39% for Mamu Shale (MS); 43.21%, 21.33%, and 10.36% for Enugu Shale (ES); 53.35%, 15.64%, and 7.17% for Nkporo Shale (NS); and 51.24%, 17.25%, and 7.78% for Agwu Shale (AS). However, the shales were depleted in Na₂O, MgO, K₂O, MnO, TiO₂, CaO, and P₂O₅. The trace element ratios of Ni/Co and Cu/Zn of the shale suggest an oxic depositional environment. The average SiO₂ vs. Al₂O₃ ratio of the shales indicated textural maturity. Compared to the PAAS standard, the shales plot below the PAAS value of 0.85, suggesting a high degree of maturity and intensive chemical weathering, further confirmed on a CIA vs. PIA plot. On log (K₂O/Na₂O) against SiO₂ and tectonic setting discriminant function diagrams, the shales plot mostly in the field of passive continental margin tectonic setting. The discriminant function diagrams as well as Al₂O₃/TiO₂ ratio of the shales showed that they were derived from a mixed source (mafic and intermediate igneous rocks).

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.52-61
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• 1984

Pot and laboratory tests were undertaken to investigate the influence of silicate fertilization on butachlor phytotoxicity to rice. Growth of rice seedlings at 150 ppm of $SiO_2$ was stimulated, while adverse effect was observed over 300 ppm of $SiO_2$ and growth reduction was enhanced with combination of butachlor and $SiO_2$ Rice growth in pot trial at 150kg/10a of silicate fertilization was not influenced by recommended amounts of butachlor and nitrofen, however, the growth of Seokwang byeo at 300kg/10a of silicate was markedly retarded by butachlor in the initial stage of growth. Growth reduction of Seokwang byeo caused by combined application of silicate and butachlor was recovered 50 days after herbicide application. Growth reduction from butachlor was not influenced by pH level and also degradation behaviors of butachlor in submerged soil was not altered by silicate fertilization. Adsorbed amount of butachlor on rice root was increased with addition of $SiO_2$ and its amount in Seokwang byeo was higher than that of Jinju byeo. Butachlor absorption by Seokwang byeo was accelerated by 150 ppm of $SiO_2$ applied simultaneously, but those effect was not encountered in Jinju byeo. Butachlor absorption of rice seedlings was also increased by 150 ppm of $K_2O$, while CaO hindered the absorption and $Na_2O$ had no effect on the absorption. Residual level of butachlor in Seokwang byeo treated with combined solution of butachlor and $SiO_2$ was continued higher than that with butachlor alone during 10 days after transplantation to culture solution.

• Economic and Environmental Geology
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• v.29 no.5
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• pp.545-559
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• 1996

Rare metal (Nb-Zr-REE) ore deposits are located in the Chungju area. Geotectonically, the rare metal ore deposits are situated in the transitional zone between Kyeonggi massif and Okcheon belt. The rare metal deposits are distributed in Kyemyeongsan Formation which consist of schist and alkaline igneous rocks. Alkali granite has suffered extensive post-magmatic metasomatism and hydrothermal processes. The ore contains mainly Ce-La, Ta-Nb, Y, Y-Nd, Nd-Th group minerals. More than 15 RE and REE minerals are found in the ore deposits. Allanite, one of the Ce-La rich REE minerals belonging to the epidote group, is the most common mineral in the studied area. The allanite- bearing rocks may be devided into seven types by features of occurrence and mineral associations; zircon type (ZT), allanite-vein type (AT), feldspar type (KT), fluorite type (FT), quartz-mica type (QT), iron-oxide type (MT), and amphibole type (HT). The allanite veins (AT) and zircon rich rocks (ZT) contain the highest total REE contents. Differences in REE abundance can be interpreted in terms of varying portions of magmatic hydrothermal fluid. Petrographical and chemical data are presented for allanites which were collected from different types. The allanites show wide variations in optical properties, due in part to differences in their chemical composition (depending on the types) and to the degree of crystallinity of the individual specimens. Allanite metamicts in biotite are generally surrounded by well developed pleochroic haloes. Usually, allanite is accompanied by zircon and other REE-bearing minerals. CaO and total REE contents $({\sum}RE_2O_3)$ range from 9.29 to 18.79% and 11.66 to 26.31%, respectively. Also, SiO, (28.87~32.61%), $Al_2O_3$ (8.30~16.88%), and $Fc_2O_3$ (16.74~24.38%) contents show varying contents from type to type. The ${\sum}RE_2O_3$ of allanite has positive relationships with $Fe_2O_3$ and negative relaton with CaO, $SiO_2$, and $Al_2O_3$ Backscattered electron microscope images (BEl) of allanite shows that the its mineral composition and texture is very complex. The allanite-bearing hosts show distinct light REE enrichment with strong negative Eu anomaly except for HI. The HT has an almost flat REE distribution pattern with a small negative Eu anomaly. The chemical variation of the allanites with occurrences and mineral association can be related to condition of temperature and oxidation states in precipitation environment.

• Korean Journal of Agricultural Science
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• v.9 no.1
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• pp.250-259
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• 1982

The Larch was known unsuitable species for the wood cement board owing to its some inhibitory substances. Therefore this research was carried out to evaluate the effect of pretreatments and chemical additives on the properties of woodflake cement board from Japanese larch (Larix leptolepis) grown in Korea. In order to improve the board qualities, the woodflakes were treated by cold water or dilute NaOH solutions(0.1, 0.5, and 2.0%), and also some chemicals($CaCl_2$, $Al_2Cl_3$ and $Na_2SiO_4$) added to the wood cement mixture. The results obtained are summarized as follow; 1. The wood cement boards from the woodflake treated with 0.1% NaOH showed remarkable higher bending strengths and internal bonding strengths than those from the flake pretreated with cold water. 2. The bending strengths showed over $60kg/cm^2$, i.e. the standard strength of JIS A-5417, with pretreatments of NaOH over 0.1% and additive of $CaCl_2$ 3.0%. The maximum strengths showed at about 0.5 of every additives. 3. Addition of $CaCl_2$ and $Al_2Cl_3$, in the case of pretreated wood with NaOH above 0.1%, had effects on increasing the internal bonding strengths of sample boards. 4. The thickness swellings became decreasing along with the increasing NaOH pretreatment concentntration. 5. The equilibrium conditions of the sample boards pretreated with NaOH over 0.1% and added with $Al_2Cl_3$ and $CaCl_2$ were maintained at 9.0~10.5% moisture contents. 6. The specific gravity of the samples showed close relationships with strength properties.

• Resources Recycling
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• v.8 no.3
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• pp.9-17
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• 1999

The study investrgated the properti es of lh$\xi$ dust~ from felToalloy manufacture, The chemical composition, composItron material, particle size and shapes of the bulk dust, sized dust and magnetically separated dust were llivestigated. As the result, we s suppose that the dust from HLgh Carbon Fenomauganesc Manufacturing Process is not sufficient as soource material of Mn because of the low Mn conteut (13.5%) aud complicated composition material The dust from Bag Filter of AOD Process is m mainly made up of $0.2~2\mu\textrm{m}$ $Mn_3O_4$ (Hausmatmite) particle in spherical shape and the Mn content is 63.1%. The dust from Cooler of AOD Process is mainly made up of coarse $Ca(OH)_2$ Mn, $Fe_yO_2$ $SiO_2$ and fine $Mn_3O_1$.

• Korean Journal of Materials Research
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• v.22 no.12
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• pp.669-674
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• 2012

Yellow phosphor dispersed color conversion glasses are promising phosphor materials for white LED applications because of their good thermal durability, chemical stability, and anti-ultraviolet property. Six color conversion glasses were prepared with high Tg and low Tg specimens of glass. Luminous efficacy, luminance, CIE (Commission Internationale de l'Eclairage) chromaticity, CCT (Correlated Color Temperature), and CRI (Color Rendering Index) of the color conversion glasses were analyzed according to the PL spectrum. Color conversion glasses with high Tg glass frit, sintered at higher temperature, showed better luminous properties than did color conversion glasses with low Tg glass frit. The characteristics of the color conversion glass depended on the glass composition rather than on the sintering temperature. The XRD peaks of the YAG phosphor disappeared in the color conversion glass with major components of $B_2O_3$-ZnO-$SiO_2$-CaO and, in the XRD results, new crystalline peaks of $BaSi_2O_5$ appeared in the color conversion glass with major components of $Bi_2O_3$-ZnO-$B_2O_3$-MgO. The characteristics of CIE chromaticity, CCT, and the CRI of low Tg color conversion glasses showed worse color properties than those of high Tg color conversion glasses. However, these color characteristics of low Tg glasses were improved by thickness variation. So color conversion glasses with good characteristics of both luminous and color properties were attained.

• Journal of the Korean Ceramic Society
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• v.43 no.10 s.293
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• pp.646-652
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• 2006

Several oxynitride glasses were fabricated by means of adding $Si_3N_4$ powders as nitrogen source to Ca-Al-Si-O-N (CAS) and Mg-Al-Si-O-N (MAS) glass powders, and heat-treated in graphite crucible at 1600$^{\circ}C$ for 1 h. The physical and mechanical properties as well as impact resistance were generally increased and compared with each other. The impact resistance properties of those manufactured glasses were evaluated by DOP (depth of penetration) method which is a way to analyze armor materials. There were two means to be used herein; the copper jet impacted at hyper velocity by exploding K2l5 warhead and tungsten heavy alloy (WHA) impact bar at high velocity by firing in 30 mm solid propellent gun. The impact resistance properties against copper jet were increased and then decreased with increasing nitrogen content, while those against WHA bar were not changed apparently with nitrogen content.