• Title/Summary/Keyword: $CoSb_3$

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Characterization of Korean Archaeological Artifacts by Neutron Activation Analysis (II). Multivariate Classification of Korean Ancient Glass Pieces (중성자 방사화분석에 의한 한국산 고고학적 유물의 특성화 연구 (II). 다변량 해석법에 의한 고대 유리제품의 분류 연구)

  • Chul Lee;Oh Cheun Kwun;Ihn Chong Lee;Nak Bae Kim
    • Journal of the Korean Chemical Society
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    • v.31 no.6
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    • pp.567-575
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    • 1987
  • Fourty five ancient Korean glass pieces have been determined for 19 elements such as Ag, As, Br, Ce, Co, Cr, Eu, Fe, Hf, K, La, Lu, Na, Ru, Sb, Sc, Sm, Th and Zn, and for one such as Pb by instrumental neutron activation analysis and by atomic absorption spectrometry, respectively. The multivariate data have been analyzed for the relation among elemental contents through the variance-covariance matrix. The data have been further analyzed by a principal component mapping method. As the results training set of 5 class have been chosen, based on the spread of sample points in an eigen vector plot and archaeological data. The 5 training set consisting of 36 species and a test set consisting of 9 species bave finally been analyzed for the assignment to certain classes or outliers through the statistical isolinear multiple component analysis (SIMCA). The results have showed the whole species for 5 training set and 3 species in the test set are assigned appropriately and these are in accord with the results by principal component mapping.

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Geochemistry, Secondary Contamination and Heavy Metal Behavior of Soils and Sediments in the Tohyun Mine Creek, Korea (토현광산 수계에 분포하는 토양과 퇴적물의 지구화학적 특성, 이차적 오염 및 중금속의 거동)

  • 이찬희;이현구;윤경무
    • Economic and Environmental Geology
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    • v.34 no.1
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    • pp.39-53
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    • 2001
  • Environmental pollution of the Tohyun mine creek area was investigated on the basis of geology, mineralogy and geochemistry. In soils and sediments of the mine area, ${Al_2}{O_3}/{Na_2O}$ and ${K_2}O/{Na_2}O$ ratios are partly negative correlation against ${SiO_2}/{Al_2}{O_3}$, respectively. Geochemical characteristics of some trace and rare earth elements such as V/Ni, Ni/Co, La/Ce, Th/Yb, Th/U, La/Th, ${La_N}/{Yb_N}$, La/Sc and Sc/Th are revealed a narrow range and homogeneous compositions may be explained by simple source lithology. These results suggest that sediments source of the host shale around the mine area could be originated by basic to intermediate igneous rocks. Mineral compositions of soil and sediment near the mine area were partly variable mineralogy, which are composed of quartz, mica, feldspar, chlorite, clay minerals and some pyrite. Soils and sediments with highly concentrated heavy minerals, gravity separated mineralogy, are composed of some pyrite, arsenopyrite, chalcopyrite, sphalerite, galena, goethite and various kinds of hydroxide minerals on the polished sections. As normalized by bed rock composition, average enrichment indices of major elements in sediments, precipitates, farmland soils and paddy soils are 1.0, 1.7, 0.9 and 0.8, respectively. Maximum concentration of environmental toxic elements in the mine creek are detected with Ag = 186 ppm, As = 17,100 ppm, Bi = ]27 ppm, Cd = 77 ppm, Cu = 12,299 ppm, Pb = 8,897 ppm, Sb = 1,350 ppm, W = 599 ppm and Zn = 12,250 ppm, which are increasing with total FeO increasing, and extremely high concentrations of surface sediments and precipitates near the waste rock dump. These toxic elements (As, Bi, Cd, Cu, Pb, Sb, W and Zn) of the samples, normalizing by host rock concentration, revealed that average enrichment index is 106.0 for sediments, 279.6 for precipitates, 3.5 for farmland soils and 1.6 for paddy soils. However, on the basis of EPA values, enrichment indices of all the samples are 40.7, 121.4, 1.3 and 0.6, respectively.

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인삼근회분(人蔘根灰分)의 계통분석(系統分析)에 관(關)한 시험(試驗)

  • Kim, Hyeong-Su
    • Applied Biological Chemistry
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    • v.1
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    • pp.37-40
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    • 1960
  • (1) Inorganic paper chromatography를 삼근회분(蔘根灰分)의 계통분석(系統分析)에 응용(應用)했으며 소량(少量)의 회분(灰分)으로 일제분석(一齊分析)이 가능(可能)하였다. (2) 계통분석(系統分析)에는 6족법(族法)으로 하였으며, Hg, Pb, Cd, Cu, As, Sb, Al, Fe, Co, Mn, Zn, Ca, Na, K 등의 양(陽) ion이 삼근회분중(蔘根灰分中)에서 검출(檢出)되었다. ($Ba^{++}$는 시험불구득(試驗不求得)으로 불실시(不實施)) (3) 삼근회분(蔘根灰分)의 양(陽) ion중(中) Co, Zn, Mn 등은 그들의 식물영양학적(植物榮養學的) 면(面)에서 관심사(關心事)가 될 것이다. (귀금속(貴金屬)과 음(陰) ion에 대(對)해서는 차후(次後) 계속예정(繼續豫定)임)

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Research for Controlled Thermal Conductivity of p-Type Skutterudite Materials (P-type Skutterudite 열전소재의 열전도도 제어 연구)

  • Son, Geon Sik;Choi, Soon Mok
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.11
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    • pp.671-675
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    • 2016
  • Skutterudite materials show PGEC (phonon glass electron crystal) characteristics which is an optimal strategy for designing high performance thermoelectric materials. Now two methods are in parallel to control thermal conductivity of skutterudites, a rattler-atoms doping method and a process for nanostructured bulk materials. Amount of rattler atoms in p-type skutterudite are depends on a Fe/Co ratio of matrix, and the optimal Fe/Co ratio has been reported about from 3:1 to 3.5:0.5 in $R(Fe,Co)_4Sb_{12}$ structure. In this paper, our discussion for rattler doping research was concentrated on double-rattler systems and DD-doped systems in p-type skutterudites. A melt spinning precess combined with high energy ball milling were suggested as a strategy for nanostructured bulk materials with PGEC (phonon glass electron crystal) characteristics in p-type skutterudites.

Influence of different universal adhesives on the repair performance of hybrid CAD-CAM materials

  • Demirel, Gulbike;Baltacioglu, Ismail Hakki
    • Restorative Dentistry and Endodontics
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    • v.44 no.3
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    • pp.23.1-23.9
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    • 2019
  • Objectives: The aim of this study was to investigate the microshear bond strength (${\mu}SBS$) of different universal adhesive systems applied to hybrid computer-aided design/computer-aided manufacturing (CAD-CAM) restorative materials repaired with a composite resin. Materials and Methods: Four types of CAD-CAM hybrid block materials-Lava Ultimate (LA), Vita Enamic (VE), CeraSmart (CS), and Shofu Block HC (SH)-were used in this study, in combination with the following four adhesive protocols: 1) control: porcelain primer + total etch adhesive (CO), 2) Single Bond Universal (SB), 3) All Bond Universal (AB), and 4) Clearfil Universal Bond (CU). The ${\mu}SBS$ of the composite resin (Clearfil Majesty Esthetic) was measured and the data were analyzed using two-way analysis of variance and the Tukey test, with the level of significance set at p < 0.05. Results: The CAD-CAM block type and block-adhesive combination had significant effects on the bond strength values (p < 0.05). Significant differences were found between the following pairs of groups: VE/CO and VE/AB, CS/CO and CS/AB, VE/CU and CS/CU, and VE/AB and CS/AB (p < 0.05). Conclusions: The ${\mu}SBS$ values were affected by hybrid block type. All tested universal adhesive treatments can be used as an alternative to the control treatment for repair, except the AB system on VE blocks (the VE/AB group). The ${\mu}SBS$ values showed variation across different adhesive treatments on different hybrid CAD-CAM block types.

Carbon monoxide activation of delayed rectifier potassium currents of human cardiac fibroblasts through diverse pathways

  • Bae, Hyemi;Kim, Taeho;Lim, Inja
    • The Korean Journal of Physiology and Pharmacology
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    • v.26 no.1
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    • pp.25-36
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    • 2022
  • To identify the effect and mechanism of carbon monoxide (CO) on delayed rectifier K+ currents (IK) of human cardiac fibroblasts (HCFs), we used the wholecell mode patch-clamp technique. Application of CO delivered by carbon monoxidereleasing molecule-3 (CORM3) increased the amplitude of outward K+ currents, and diphenyl phosphine oxide-1 (a specific IK blocker) inhibited the currents. CORM3-induced augmentation was blocked by pretreatment with nitric oxide synthase blockers (L-NG-monomethyl arginine citrate and L-NG-nitro arginine methyl ester). Pretreatment with KT5823 (a protein kinas G blocker), 1H-[1,-2,-4] oxadiazolo-[4,-3-a] quinoxalin-1-on (ODQ, a soluble guanylate cyclase blocker), KT5720 (a protein kinase A blocker), and SQ22536 (an adenylate cyclase blocker) blocked the CORM3 stimulating effect on IK. In addition, pretreatment with SB239063 (a p38 mitogen-activated protein kinase [MAPK] blocker) and PD98059 (a p44/42 MAPK blocker) also blocked the CORM3's effect on the currents. When testing the involvement of S-nitrosylation, pretreatment of N-ethylmaleimide (a thiol-alkylating reagent) blocked CO-induced IK activation and DL-dithiothreitol (a reducing agent) reversed this effect. Pretreatment with 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)-21H,23H porphyrin manganese (III) pentachloride and manganese (III) tetrakis (4-benzoic acid) porphyrin chloride (superoxide dismutase mimetics), diphenyleneiodonium chloride (an NADPH oxidase blocker), or allopurinol (a xanthine oxidase blocker) also inhibited CO-induced IK activation. These results suggest that CO enhances IK in HCFs through the nitric oxide, phosphorylation by protein kinase G, protein kinase A, and MAPK, S-nitrosylation and reduction/oxidation (redox) signaling pathways.

Conduction Mechanism of Non-linearity ZnO Varistor in the Prebreakdown region (비선형성 ZnO 바리스터의 Prebreakdown 영역에서의 전도 현상)

  • 한세원;강형부
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1995.11a
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    • pp.74-76
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    • 1995
  • ZnO varistor with composition of ZnO(90wt%)-Bi$_2$O$_3$(3wt%)-Sb$_2$O$_3$(3.6wt%)-CO$_2$O$_3$(1.16wt%)-NiO(0.88wt%)-MnO$_2$(0.71wt%)-Cr$_2$O$_3$(0.93wt%) according to Al$_2$O$_3$addtive was fabricated by sintering methods. The effects of Al$_2$O$_3$dopant on the I-V characteristics of ZnO varistors were investigated. These changes of electric properties were found to be caused by the variation of grains and grain boundary related to Al$_2$O$_3$dopting. And the conductive mechanism of ZnO varistor in prebreakdown region were investigated with defect model.

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Effects of Expanders in Manufacture and Microstructure of ZnO Varistor with $Al_2O_3$ (ZnO 바리스터의 제조에서 분산제 영향 및 $Al_2O_3$ 첨가에 따른 미세구조 연구)

  • Soh, J.J.;Han, S.W.;Kim, H.S.
    • Proceedings of the KIEE Conference
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    • 1995.11a
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    • pp.345-347
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    • 1995
  • ZnO varistor with composition of ZnO(90wt%)-$Bi_2O_3$(3wt%)-$Sb_2O_3$(3.61wt%)-$CO_2O_3$(1.16wt%)-NiO (0.88wt%)-$MnO_2$(0.71wt%)-$Cr_2O_3$(0.93wt%) according to $Al_2O_3$ addtive was fabricated by sintering methods. The optimal densification were established for the processing conditions of 8000 rpm 190$^{\circ}C$ spray drying and 1200$^{\circ}C$ 2hrs sintering. Then here investigated how additive compotions and processing variables affected the electrical and the phesical properties of these ZnO varistors.

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Effects of Annealing on the Microstructure and Electrical Properties of ZnO Varistor (ZnO 바리스터 제조시 소결후 열처리 조건에 따른 미세구조 및 전기적 특성에 관한 연구)

  • Soh, J.J.;Han, S.W.;Kim, H.S.
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1679-1681
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    • 1996
  • ZnO varistor with composition of 89wt%-ZnO, 3.0wt%-$Bi_{2}O_{3}$, 3.6wt%-$Sb_{2}O_{3}$, 1.16wt%-CoO, 0.88wt%-NiO, 0.71wt%-$MnO_2$, 0.93wt%-$Cr_{2}O_{3}$, 0.013wt%-$Al_{2}O_{3}$ was fabricated by sintering methods. The effects of annealing on the J-E characteristics of ZnO varistors were investigated. These changes of electric properties were found to be caused by the variation of grains and grain boundary related to annealing. And the conductive mechanism and micostructure of ZnO varistor were researched using I-V meter, SEM and XRD.

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Effect of the Piezoelectric characteristics on the PSN-PNN-PZT Ceramics added with Mn and Cu (Mn 및 Cu가 PSN-PNN-PZT 세라믹스의 압전특성에 미치는 영향)

  • Lee, Sun-Kon;Lee, Ki-Su
    • Journal of the Korean Society of Safety
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    • v.24 no.4
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    • pp.22-27
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    • 2009
  • In this paper, the minuteness structure, piezoelectric, and dielectric characteristics of $0.95{Pb(Sb_{1/2}Nb_{1/2})_{0.02})_{0.02}(Ni_{1/3}Nb_{2/3})_{0.13}(Zr_{0.48}Ti_{0.52})_{0.85}}O_3+0.05Pb(CO_{1/2}W_{1/2})O_3+0.3%$ $MnO_2+0.3wt%$ CuO ceramics has been systematically investigated as a function of the sintering temperature after manufacturing the specimens with a general method. This study will be very helpful as basic data for developing ceramic materials, More study in a soon time for improving stability of temperature, effect of adds and stability and reality of frequency with improved production condition for specimens will give a powerful potentiality as a applied material of dielectric ceramics.