• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.3
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• pp.198-207
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• 1999

Five core sediments acquired from the Lake Shihwa are analyzed for variations of sedimentary environment and heavy metal pollution after the Shihwa seawall construction. The depositional environment of the study area is divided into anoxic, oxic and mixed suboxic conditions based on the C/N ratio and C/S ratios of organic matters. Controlling factors for redox condition are the water depth and the difference in industrial effluents supply. Correlations among geochemical elements (Mn, U, Mo) show a distinctive difference and thus can be used as an indicator of redox condition. The content of Al, Ti are dependent on the sediment characteristics, and the contents of heavy metals (Cr, Ni, Cu, Zn, and Pb) indicate heavy metal pollution. The concentrations of heavy metals are higher near Shiswa-Banwol industrial complexies than the central part of Lake Shihwa. Especially, the accumulation of the heavy metal at the surface sediments near Shihwa-Banwol industrial complex are two to eight times higher than in the center of Lake Shihwa.

• Journal of Environmental Science International
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• v.23 no.5
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• pp.829-837
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• 2014

Titania-supported chromium oxides with different loadings have been embarked in catalytic oxidation of trichloroethylene (TCE) to inquire association of the formation of crystalline $Cr_2O_3$ with catalytic performances. A better activity in the oxidative TCE decomposition at chosen temperatures was represented when chromium oxides ($CrO_x$) had been dispersed on pure anatase-type $TiO_2$ (DT51D) rather than on phase-mixed and sulfur-contained ones such as P25 and DT51. The extent of TCE oxidation at temperatures below $350^{\circ}C$ was a strong function of $CrO_x$ content in $CrO_x$/DT51D $TiO_2$, and a noticeable point was that the catalyst has two optimal $CrO_x$ loadings in which the lowest $T_{50}$ and $T_{90}$ values were measured for the TCE oxidation. This behavior in the activity with respect to $CrO_x$ amounts could be associated with the formation of crystalline $Cr_2O_3$ on the support surface, that is less active for the oxidation reaction, and an easier mobility of the surface oxygen existing in noncrystalline $CrO_x$ species with higher oxidation states, such as $Cr_2O_8$ and $CrO_3$.

• Journal of Conservation Science
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• v.33 no.2
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• pp.131-147
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• 2017

The purpose of this study is to analyze the characteristics of Punchong and Whiteware pottery excavated from the kiln site in Dongkok-Town, Gimge. Scientific analysis is carried out to evaluate the physical and chemical properties of the body and glaze. The physical properties indicate the gradual development of the production technology with respect to the kiln operating conditions and period. In chemical properties, the ceramic body is found to be made of raw materials from the same source, but the mixing method depends on the type of Punchong and Whiteware pottery, the production kiln, and period. Whiteware pottery is manufactured with less over 1.3% of the colorant content and more about 1.2% of the $K_2O$ flux content than Punchong pottery. This compositions allow easier vitrification at the same temperature. These characteristics which is low colorant content and high flux content become more prominent as lately. The ceramic glaze is likely to have changed the type of raw materials used after 16~17C, as the contents of MgO, $TiO_2$, MnO, $P_2O_5$ are less three to ten times than 15C.

• Journal of the Korean Ceramic Society
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• v.28 no.11
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• pp.897-907
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• 1991

This study was conducted to research the formation and the color development of CoO-ZnO-Fe2O3-TiO2-SnO2 system for the purpose of synthesizing the spinel pigments which are stable at high temperature. After preparing CoO-ZnO-Fe2O3, in which CoO causes the color, as a basic composition, $\chi$CoO.(1-$\chi$)ZnO.Fe2O3 system, $\chi$CoO.(1-$\chi$)ZnO.TiO2 system and $\chi$CoO.(1-$\chi$)ZnO.SnO2 system were prepared with $\chi$=0, 0.2, 0.5, 0.7, 1.0 mole ratio respectively. The manufacturing was carried out at 128$0^{\circ}C$ for 90 minutes. These specimens were analyzed by the reflectance measurement and the X-ray diffraction analysis and the results were summarized as follows: 1. All of the specimens formed the spinel structure and were colored with stable yellow or blue. 2. As the content of CoO and Fe2O3 in the specimens being increased, the reflectance of each specimen was measured becoming lower and the colors were changed from yellow to greyish blue and from blue to dark blue. 3. As the substituting amount of Co2+ ion for Zn2+ ion in $\chi$CoO-ZnO-TiO2-SnO2 system being increased, the colors were changed from blue to greyish blue. The colors were changed from yellow to grayish green owing to the tetrahedral Co2+ ions being increased, the octahedral Co2+ ions being decreased with increasing the amount of Sn4+ ions. 4. CoO-ZnO-Fe2O3-TiO2-SnO2 system, in which Zn2+ was substituted with Co2+ and Fe3+ was substituted with Ti4+ and Sn4+, easily formed the spinel structure without regard to the amount of substitution or the ion owing to the selectivity of the coordination number: 4 of Zn2+, 4 of Co2+, 6 of Fe3+ or 6 of Ti4+ and Sn4+.

• Proceedings of the KWS Conference
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• 1995.10a
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• pp.208-211
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• 1995

Five cast gamma titanium aluminides, Ti-45~48%Al-2%Nb-2%Cr (nominal composition in at. %), were laser welded and their weld cracking susceptibilities were evaluated. Laser power, traversing rate and preheat temperature were systematically varied to generate a series of welds exhibiting a wide range of cooling rate ($100^{\circ}C/s-10,000^{\circ}C/s$). As Al content increased and the weld cooling rate decreased, solidification cracking susceptibility increased while solid-state cracking susceptibility decreased. Through laser beam energy input control and preheat, it was determined possible to produce high quality laser welds.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.1
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• pp.38-42
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• 2001

Electric and dielectric(Ba,Sr)$TiO_3$[BST] thin films for emtal-Insulator-Semiconductor(MIS) capacitors have been studied. BST thin films wre deposted on p-Si(100) substrates bythe RF magnetron sputtering with tempratue range of 500~$600^{\circ}C$. The dielectric properties of MIS capacitors consisting of Al/BST/$SiO_2$/Si sandwich structure were evaluated ot redcue the leakage current density. The charge state densities of the MIS capacitors were determined by high frequency (1 MHz) C-V measurement. In order to reduce the leakage current in MIS capacitor, high quality $SiO_2$ layer was deposited on bare p-Si substrate. Depending on the oxygen pressure and substrate temperature both positive and negative polarities of effective oxide charge in the MIS capacitors were evaluated. It is considered that the density of electronic states, generated at the BST/$SiO_2$/p-Si interface due to the asymmetric structure within BST/$SiO_2$/Si structure, and the oxygen vacancy content has influence on the behavior of oxide charge.

• Korean Journal of Plant Resources
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• v.4 no.2
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• pp.39-45
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• 1991

Proximate compositions of the roots of cultured and wild Codonopsis lanceolata were examined as tile basic reasearch for the study of their source of processed foods.No significant difference in the contents was found between the wild root and thecultivated at 3$0^{\circ}C$ in biotronroom. In view of the results to have measured mineralswhich is included in 14 sorts of Codonopsis lanceolata and surveyed their distribution.12 kinds of minerals including T1, Co, Ge, Sm, Mo, Sc, Be, Cd, As, Ga, Bi, ph are ne-vel or little included in almost source. Other twenty-one sorts of minerals (Ni, Se,Ba, Sb, Si, Ti, B, Li, Ifs, Ca, Sr, Mn, Fe, Cu, Zn, p, Al, Na, V, Cr, K) are more or less in-cluded in all source and Ca, Mg, p, K, and Fe are metals that are included in large qu-entities in comparison with others. No minerals difference in the contents was foundbetween the cultivated temperature. The content of elements of inorganic metal differsaccording to the part of C. lanceolata.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.848-850
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• 1999

In this study, PZT etching was performed using planar inductively coupled Ar(20)/$Cl_2/BCl_3$ plasma, The etch rate of PZT film was 2450 $\AA/min$ at Ar(20)/$BCl_3$(80) gas mixing ratio and substrate temperature of $80^{\circ}C$. X-ray photoelectron spectroscopy (XPS) analysis for film composition was utilized. The chemical bond of PbO is broken by ion bombardment, and the peak of metal Pb in a Pb 4f peak begins to appear upon etching, decreasing Pb content faster than Zr and Ti. As increase content of additive $BCl_3$, the relative content of oxygen decreases rapidly. We thought that abundant Band BCl radicals made volatile oxy-compound such as $B_{x}O_{y}$ and/or $BClO_x$ bond. To understand etching mechanism, Langmuir probe and optical emission spectroscopy (OES) analysis were utilized for plasma diagnostic.

• The Korean Journal of Ceramics
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• v.6 no.2
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• pp.116-119
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• 2000

The a-axis and c-axis prefer oriented SBT thin films could be deposited on Pt(111)/Ti/$SiO_2$$650^{\circ}C$). The c-axis preferred orientation of SBT film can be obtained by Sr deficiency and high compressive stress. However, the a-axis-oriented grains can be formed under stoichiometric Sr content and nearly stress-free state.

• 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.