• Journal of the korean society of oceanography
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• v.32 no.3
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• pp.112-119
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• 1997

Coastal sediments collected near the Youngkwang Nuclear Power Plant were analysed for major(Al$_2$O$^_3$, Fe$^_2$O$^_3$, MgO, CaO, Na$^_2$O, K$^_2$O, TiO$^_2$, MnO), trace (Ba, Sr, V, Co, Cr, Cu, Ni, Zn, Pb) metal, and P$^_2$O$^_5$ contents. The composition of bulk metals from most stations fits within the range as those in the average crustal and sedimentary rocks, suggesting that the anthropogenic perturbation of these components is insignificant. The abundance and distribution of total contents for the majority of metals in the surface sediment could be explained by the grain size and were associated with mud (<63 ${\mu}$m) contents. However, distributions of Ca, K, Sr and Ba did not have any significant association with the sediment grain size. This may be due to the geochemical coherence among these metals in certain minerals abundant in coarse grained fractions. The distribution of Pb appears to be partly affected by the contribution from aerosol fallout. Using the R'-mode factor analysis, we show that the variance of the metal contents could be explained by four factors which account for 93.7% of the total variance. It appears that texturally controlled and/or sorting factors influenced by fine fraction are the most dominant factors which determine the relative abundance and distribution of metals in the study area.

• Korean Journal of Materials Research
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• v.13 no.12
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• pp.846-849
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• 2003

Doping effect of various ions in Bi-layered ferroelectric $SrBi_2$$Nb_2$$O_{9}$ (SBN) ceramics was studied. Undoped SBN ceramic and SBN ceramics doped with $Ba^{2＋}$, $Pb^{2＋}$,$ Ca^{2＋}$ , $Bi^{3＋}$ , $La^{3＋}$ , $Ti^{4＋}$ , $Mo^{6＋}$ , and $W^{6＋}$ ions were made by a solid state reaction. Dielectric constants were measured with temperature. Ferroelectric transition temperature decreased with $Pb^{2＋}$ , $Ba^{2＋}$ , $La^{3＋}$ doping, but the transition temperature increased with $Ca^{2＋}$ , $Bi^{3＋}$ , $Ti^{4＋}$, $Mo^{6＋}$ , or$ W^{6＋}$ ionic doping. These results show that the ion size plays an important role in the ferroelectricity of SBN ceramic.

• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.309-314
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• 2000

In the present study, preliminary experimental results of the change in the properties of perovskite-type oxides caused by the $^{18}O$- exchange have been reported. Two systems were selected for the exchange, (1) $ATiO_3$(A=Ca,Sr,Ba) and (2) manganese perovskite. The dielectric properties of isotope-exchanged $SrTi^{18}O_3$showed a drastic change from a quantum paraelectricity below 3K to ferroelectric-like behavior with a peak at 23K and an enhanced dielectric constant, 35000 at the peak. On the contrary, the $T_c$ for $BaTiO_3$was found to increase by 0.9K. The observed isotope shift of $T_c$ as well as $T_co$ for the manganese perovskites is correlated with the key parameters controlling the lattice such as $Mn^{3+}$ content, average ionic radius of the A-site cation <$r_A$> ad A-site ionic disorder $\sigma^2$.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.3-9
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• 1999

The grain morphology, the changes in morphology and Jc with the thermo-mechanical treatment (TMT) history, the field dependence of Jc and the nature of intergranular bonding were studied in $T_{10.8}$$Pb_{.2}$$Bi_{0.2}$$Sr_{1.8}$$Ba_{0.2}$$Ca_{2.2}$$Cu_{3}$$O_{z}$/Ag tapes. As a result, incorporation of intermediate rolling during the final heat-treatment resulted in of plate-like TI-1223 grains, and thus enhanced Jc. Jc's near 2.5$\times$104 A/cm2 at 77 K and 0 T were obtained in just rolled tapes with an excellent reproducibility. The high Jc's seem to grain-connectivity easy recovery of excellent grain-connectivity during final heat-treatment after inter -mediate rolling, probably due to retarded T1 evaporation and excessive Ca content in the present composition. The strong field dependence of Jc even in low fields, however, indicated that there still existed significant weak-links and the degree of directional grain-alignment was far from the desired one. The intergranular binding in the tapes seemed to be mainly dominated by SIS junctions.

• Journal of the Korean earth science society
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• v.27 no.1
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• pp.49-60
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• 2006

The purpose of this study is to investigate geochemical characteristics for stream sediments in the Naju area. We collected 139 stream sediments samples from primary channels. Samples were dried slowly in the laboratory and chemical analysis was carried out using XRF. ICP-AES and NAA. In order to investigate geochemical characteristics, the geological groups categorized into granitic gneiss area, schist area, granite area, arenaceous rock area, tuff area, andesite area, and rhyolite area. Average contents of major elements for geological groups are $SiO_2\;58.37{\sim}66.06wt.%,\;Al_2O_3\;13.98{\sim}18.41wt.%,\;Fe_2O_3\;4.09{\sim}6.10wt.%,\;CaO\;0.54{\sim}1.33wt.%,\;MgO\;0.86{\sim}1.34wt.%,\;K_2O\;2.38{\sim}4.01wt.%,\;Na_2O\;0.90{\sim}1.32wt.%,\;TiO_2\;0.82{\sim}1.03wt.%,\;MnO\;0.09{\sim}0.15wt.%,\;P_2O_5\;0.11{\sim}0.18wt.%$. According to the comparison of average contents of major elements, $Al_2O_3\;and\;K_2O$ are higher in granitic gneiss area, $Fe_2O_3,\;CaO,\;P_2O_5$ are higher in tuff area, MgO and $TiO_2$ are higher in andesite area, $Na_2O_$ is higher in rhyolite area, $SiO_2$, and MnO are higher in arenaceous rock area. Average contents of minor and rare earth elements for geological groups are $Ba\;1278{\sim}1469ppm,\;Be\;1.1{\sim}1.5ppm,\;Cu\;18{\sim}25ppm,\;Nb\;25{\sim}37ppm,\;Ni\;16{\sim}25ppm,\;Pb\;21{\sim}28ppm,\;Sr\;83{\sim}155ppm,\;V\;64{\sim}98ppm,\;Zr\;83{\sim}146ppm,\;Li\;32{\sim}45ppm,\;Co\;7.2{\sim}12.7ppm,\;Cr\;37{\sim}76ppm,\;Cs\;4.8{\sim}9.1ppm,\;Hf\;7.5{\sim}25ppm,\;Rb\;88{\sim}178ppm,\;Sc\;7.7{\sim}12.6ppm,\;Zn\;83{\sim}143ppm,\;Pa\;11.3{\sim}37ppm,\;Ce\;69{\sim}206ppm,\;Eu\;1.1{\sim}1.5ppm,\;Yb\;1.8{\sim}4.4ppm$. According to the comparison of average contents of minor and rare earth elements for geological groups, Pb, Li, Cs, Hf, Rb, Sb, Pa, Ce, Eu, and Yb are higher in granitic gneiss area; Ba, Co, and Cr in schist area; Nb, Ni, and Zr in arenaceous rock area; Sr in tuff area: and Be, Cu, V, Sc, and Zn are such in andesite area.

• Economic and Environmental Geology
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• v.25 no.4
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• pp.435-446
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• 1992

REE, major and trace elements analyses of the Jurassic Daebo granite and Cretaceous Bulguksa granite were carried out to interpet their petrogenesis and relationships between petrogenesis and tectonics. Analytical results are summarized as follows. (1) $SiO_2$ content of the Bulguksa granite (aver. 74.6%) are significantly higher than those of the Daebo granite (aver. 68.1%). Major elements of $TiO_2$, $Al_2O_3$, $P_2O_5$, CaO, MgO, Total FeO, and trace elements of Co, V and Sr are negatively correlated with $SiO_2$. Incompatible elements such as Ba, Sr, Y, Zr and HREE are contained differently in the Bulguksa granites distributed in between Okchon folded belt and Kyongsang sedimentary basin. (2) Trace element abundances show a good discrimination between two goups of granitic rocks. Ba, Sr and V are enriched in Daebo granites, while Zn and Cr are depleted in them. (3) Jurassic granites have quite different Eu anomalies and REE patterns from those of Cretaceous granites: Large negative Eu anomaly in the former and mild or absent Eu anomaly in the latter. The large Eu negative of Cretaceous granitic rocks are interpreted as a differentiated product of fractional crystallization of granitic magma from the upper mantle. Meanwhile, the Daebo plutonic rocks was resulted from the partial melting of subcrustal material or crustal contamination during ascending granitic magma from the mantle. Senario of igneous activities of Mesozoic age in South Korea was proposed based on Kula-Pacific ridge subduction model.

• The Journal of the Petrological Society of Korea
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• v.11 no.1
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• pp.1-16
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• 2002

The study area is mostly composed of Precambrian Gyeonggi gneiss complex, Jurassic Daebo granites, Cretaceous tonalite and dykes, and so on. On the basis of field survey and mineral assemblage, the granites can be divided into three types; biotite granite (Gb), garnet biotite granite (Ggb) and two mica granite (Gtm). They predominantly belong to monzo-granites from the modes. Field relationship and K-Ar mica age data in the surrounding area suggest that intrusive sequences are older in order of Gtm, Ggb and Gb. Gb and Ggb, major study targets, occur as medium-coarse grained rocks, and show light grey and light grey-light pink colors, respectively. Mineral constituents are almost similar except for opaque in Gb and garmet in Ggb. Gb and Ggb have felsic, peraluminous, subalkaline and calc alkaline natures. In Harker diagram, both rocks show moderately negative trends of $TiO_2$, MgO, CaO, $Al_2O_3$, $Fe_2O_3$(t), $K_2O$ and $P_2O_5$ as $SiO_2$ contents increase. Among them, $TiO_2$, MgO and CaO show two linear trends. From the trends and the linear patterns in AFM, Sr-Ba and Rb-Ba-Sr relations, it is likely that they were originated from the same granitic magma and Ggb was differentiated later than Gb. REE concentrations normalized to chondrite value have trends of parallel LREE enrichment and HREE depletion. One data of Ggb showing a gradually enriched HREE trend may be caused by garnet accompaniment. Ggb have more negative Eu anomalies than Gb, suggesting that plagioclase fractionation in Ggb have occurred much stronger than that in Gb. In modal (Qz+Af) vs. Op, Gb and Ggb belong to magnetite-series and ilmenite-series, respectively. From the EPMA results, opaques of Gb are magnetite and ilmenite, and those of Ggb are magnetite-free ilmenite or not observed. Bimodal distribution of magnetic susceptibility reveals two different granites of Gb (332.6 ${mu}SI$) and Ggb (2.3 ${mu}SI$). Based on the paleomagnetic analysis as well as modal analysis, the main susceptibilities of Gb and Ggb reside in magnetite and mafic minerals, respectively. They belong to S-type granite of non-magnetic granite by susceptibility value. In addition, $SiO_2$ contents, $K_2O/Na_2O$, A/CNK molar ratio and ACF diagram support that they all belong to S-type granites.

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.241-245
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• 2007

[ $(Ba_{0.9-x}Sr_xCa_{0.10})TiO_3$ ] (x=0.33, 0.36) powders were prepared by sol-gel method. $(Ba,Sr,Ca)TiO_3$(BSCT) thick films, undoped and doped with $MnCO_3$ and $Yb_2O_3(0.1{\sim}0.7mol%)$, were fabricated by the screen printing method on the alumina substrate. The coating and drying procedure was repeated 6-times. The Pt bottom electrode was screen printing method on the alumina substrate. These BSCT thick films were annealed at $1420^{\circ}C$ for 2 hr in atmosphere. The upper electrodes were fabricated by screen printing the Ag paste and then firing at $590^{\circ}C$ for 10 min. And then the structured and dielectric properties as a function of the doping amount of $Yb_2O_3$ were studied. As a result of the TG-DTA, exothermic peak was observed at around $670^{\circ}C$ due to the formation of the polycrystalline perovskite phase. All BSCT thick films showed XRD patterns of typical cubic peroveskite structure. The average thickness of BSCT thick films was about $70^{\mu}m$. The curie temperature and the dielectric constant decreased with increasing $Yb_2O_3$ doped content and the relative dielectric constant of the specimen, doped with 0.5 mol% $Yb_2O_3$ at BSCT(54/36/10), showed a best value of 5018 at curie temperature.

• Economic and Environmental Geology
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• v.32 no.3
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• pp.247-260
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• 1999

Geochermical characteristics of the fluvial sediments deprnding on particle size distribution size were investigated in the respect of majir, minor and rare eath element chemisitry. Ratios of $Al_{2}O_{3}/Na_{2}O$ and $K_{2}O/Na_{2}O$ of the sediments show the homogeneous valus, and partly positive correlation with $SiO_{2}/Al_{2}O_{3}$, respecively. Characteristics of minor element ratios (V/Ni, Cr/V, Ni/Co and Zr/Hf)are within the lower and narrow range. Thesesuggested that sediment sources may be acidic to intermediate granitic rock, and may be explained by simple weathering and sedimentation. With increasing SiO2 contents, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO and MgO decreased, but those of $K_{2}O$ and $Na_{2}O$ increased, Concentrations of Ba, Be, Cs, Cu, Li, Ni, Sr, V and Zr show comparatively normal negative and some positive trends. Compared with the mean composition of granite, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, MnO, CaO and MgO in the sediments of the study area were highly enriced. Among some minor and rare earth elements, concentrations of As, Cd, Cu, and V were enriched, but those of Be, Ce, Rb, Sc, Sr and Zn were depleted when compared with average composition of granite. By decreasing of particle size fractions, SiO2, Rb and Sr conterts decreased, but concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO, MgO, $TiO_{2}$, MgO, $P_{2}O_{5}$, Be, Cu, Hf, Pb, V and Zr increased. From the correlations between particle size fractions and element concenreations, some elements of $Fe_{2}O_{3}$, CaO, MgO, $P_{2}O_{5}$, Cu, Ni, Zn and Zr showed typical trends in the secondary contramination sediments. These trends are typically shown under 100 mesh fractions. It indicates that the fraction of minus 100 mesh is the optimum size fraction for geochemical and environmental survey.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1504-1506
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• 2002

$(Ba_{0.6-x}-Sr_{0.4}Ca_x)TiO_3$ (x=0.10, 0.15, 0.20, y=$0.0{\sim}3.0$) powders were fabricated by the sol-gel method, and BSCT thick films were fabricated by the silk-screen printing method. Their structural and dielectric properties were investigated with variation of composition ratio. All BSCT thick films showed a homogeneous structure without presence of the second phase. BSCT film thickness, obtained by three cycle of printing, was approximately $80{\mu}m$. The dielectric constant and dielectric loss of the 3-coated BSCT(50/40/10) thick film were approximately 1700 and 0.07%, respectively.