• The Journal of the Petrological Society of Korea
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• v.20 no.1
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• pp.1-21
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• 2011

Eoil basalt in the Eoil basin and Yeonil basalt and its related volcanic rocks in Guryongpo and Daebo area were researched and analyzed to purse the tectonic settings and magma characteristics of those Tertiary volcanic rocks in the south-east Korean peninsula. It is highly suggested that zoning, resorption and sieve texture in plagioclase and reaction rim in pyroxene indicate unstable tectonic environments and complex volcanism in the study area. Volcanic rocks from Janggi basin are identified as basalt and basaltic andesite in TAS diagram and sub-alkaline series in terms of magma differentiation. $Na_2O$ and $K_2O$ show positive trend however FeO, CaO, MgO and $P_2O_5$ indicate negative trend in Harker variation diagram with $SiO_2$. Basaltic rocks from Eoil area are identified as calc-alkaline series in AFM diagram and show medium K series calc-alkaline in $K_2O-SiO_2$ diagram. Compatible trace elements of Co, Ni, V, Zn, and Sc in Yeonil basalt show negative trend with crystallization but incompatible trace element of Ba, Rb show positive trend with $SiO_2$ 0.81~1.00 of $Eu/Eu^*$ value suggests minor effect of plagioclase fractionation in Yeonil basaltic rocks. Plagioclase composition of Eoil basalt ranges from $An_{63.46-98.38}\;Ab_{1.62-32.96}\;Or_{0-3.58}$ (anorthite-labradorite) in core to $An_{40.89-82.44}\;Ab_{17.10-46.43}\;Or_{0-12.68}$ (bytownite-labradorite) in rim. $^{87}Sr/^{86}Sr$ and 143Nd;t44Nd ranges 0.704090~0.704717 and 0.512705~0.512822 respectively. Negative linear trends in 87Sr/86Sr and $^{143}Nd/^{144}Nd$ correlation diagram indicate that magma produced Yeonil basalt and basaltic andesite has been originated as partial melting product of mantle wedge by subducting Pacific plate affected by oceanic crust with less effect of continental crust indicating calc-alkaline magma characteristics.

• Economic and Environmental Geology
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• v.30 no.6
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• pp.553-566
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• 1997

Origin, behavior and enrichment of environmental toxic elements from the Deokpyeong area were investigated on the basis of major, trace and rare earth element geochemistry. Coaly metapelites of the Deokpyeong area are subdivided into grey phyllite, dark grey phyllite, coaly slate and black slate, which are interbedded along the Ogcheon Supergroup. The coaly slate had been mined for coal, but mining is closed. The coaly and black slates are lower contents of $SiO_2$ and $Al_2O_3$, and higher contents of LOI, CaO, $Na_2O$ and BaO as compared with the phyllitic rocks. Rare earth elements are highly enriched in the coaly and black slate. Average compositions (ppm) of minor and/or environmental toxic elements in the coaly and black slate are revealed as As=127, Ba=30,163, Cd=18, Cr=740, Cu=84, Mo=378, Pb=43, Sb=12, Se=44, U=144, V=8,147 and Zn=292, which are extremely high concentrations than those in the NASC compositions. Major elements (average enrichment index; 5.34) in the coaly metapelites are mostly depleted, excepting $P_2O_5$ and BaO, normalized by NASC. Rare earth elements (average enrichment index; 1.48) are enriched in the coaly slate. On the basis of NASC, minor and/or environmental toxic elements in the coaly metapelites were strongly enriched of all the elements with the exception of Co, Cs, Ni and Sr. Average enrichment index of trace elements in coaly metapelite is 31.51 (coaly slate; 51.94 and black slate; 15.46). Especially, enrichment index of potentially toxic elements (As, Ba, Cr, Cu, Mo, Ni, Sb, Se, U, V and Zn) of the rock is 46.10 (grey phyllite; 7.15, dark grey phyllite; 4.77, coaly slate; 88.96 and black slate; 22.11). These coal formations were deposited in basin of boundary between terrestrial and marine environments deduced to carbon, sulfur (C/S=2.2 to 275.7), trace and rare earth elements characteristics. Irregular behavior and dispersion between major, minor and rare earth elements of those metapelites indicates a variable source materials, incomplete mixing of differential source and/or reequilibrium of diagenesis and metamorphism.

• Electrical & Electronic Materials
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• v.5 no.3
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• pp.284-294
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• 1992

합성용질확산법으로 GaP단결정을 성장시키고 몇가지 성질을 조사하였다. 정지상태에서 결정의 성장속도는 1.75[mm/day]이었고 결정성장용 석영관을 전기로내에서 하강시키므로써 양질의 GaP 단결정을 성장하였다. 에치피트밀도는 결정의 성장축 방향으로 3.8*$10^{4}$[$cm^{-2}$]부터 2.3*$10^{5}$[$cm^{-2}$] 까지 증가하였다. 성장된 GaP결정의 이동도와 캐리어농도는 실온에서 197.49[$cm^{2}$/V.sec]와 6.75*$10^{15}$[$cm^{-3}$]이었고 77K의 온도에서는 266.91[$cm^{2}$ /V.sec]와 3.13*$10^{14}$[$cm^{-3}$]이었다. 에너지갭의 온도의존성은 실험적으로 $E_{g}$(T)=2.3383-(6.082*$10^{-4}$) $T^{2}$/(373.096+T)[eV]로 구하여졌다. 저온에서 측정된 광루미네센스 스펙트럼은 구속된 여기자의 복사재결합과 재결합 과정에 포논의 참여로 인하여 에너지갭 부근의 복잡한 선 스펙트럼이 나타났고 얕은 준위의 Si도너와 Zn억셉터준위 사이에서의 복사재결합 및 이에 대한 1LO, 2LO의 포논복제가 나타났으며 S $i_{Ga}$ -S $i_{p}$의 쌍방출에 의하여 1.8932[eV]에서 넓은 반치전폭의 피크가 나타났다. GaP의 적외선 흡수는 TO, LO, LA, T $A_{1}$, T $A_{2}$ 포논들의 이중결합모드와 G $a_{2}$O의 진동모드 및 Si도너와 Zn억셉터들에 의하여 일어났다. Zn를 확산시키어 제작한 p-n GaP발광다이오드는 실온에서의 발광중심피크가 6250[.angs.]이었고 최대광출력은 0.0916[mW], 양자효율은 0.51%이었다.이었다.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.373-376
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• 2008

New glass compositions for lead free, low temperature sealing glass frit was examined in $ZnO-V_2O_5-P_2O_5$ glass system which can be used sealing material for PDP to be made of soda lime glass substrates. Among many glass compositions, KFS-C glass showed low glass transition point (Tg) and good fluidity and adhesion characteristics when it was tested by flow button method at low temperature of $420^{\circ}C$. Its Tg was $317^{\circ}C$ and thermal expansion coefficient (CTE) was $70{\times}10^{-7}/K$. The glass frit was mixed with an organic vehicle to make a paste and it was dispensed and sealed with soda lime glass substrates at $420^{\circ}C$ for 10min. Sealed glass panels also showed good adhesion strength even sealed at low temperature of $420^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.217-217
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• 2016

The amorphous InGaZnO (a-IGZO) is widely accepted as a promising channel material for thin-film transistor (TFT) applications owing to their outstanding electrical properties [1, 2]. However, a-IGZO TFTs have still suffered from their bias instability with illumination [1-4]. Up to now, many researchers have studied the sub-gap density of states (DOS) as the root cause of instability. It is well known that defect states can influence on the performances and stabilities of a-IGZO TFTs. The defects states should be closely related with the deposition condition, including sputtering power, and pressure. Nevertheless, it has not been reported how these defects are created during conventional RF magnetron sputtering. In general, during conventional RF magnetron sputtering process, negative oxygen ions (NOIs) can be generated by electron attachment in oxygen atom near target surface and then accelerated up to few hundreds eV by a self-bias; at this time, the high energy bombardment of NOIs induce defects in oxide thin films. Recently, we have reported that the properties of IGZO thin films are strongly related with effects of NOIs which are generated during the sputtering process [5]. From our previous results, the electrical characteristics and the chemical bonding states of a-IGZO thin films were depended with the bombardment energy of NOIs. And also, we suggest that the deep sub-gap states in a-IGZO as well as thin film properties would be influenced by the bombardment of high energetic NOIs during the sputtering process.In this study, we will introduce our novel technology named as Magnetic Field Shielded Sputtering (MFSS) process to prevent the NOIs bombardment effects and present how much to be improved the properties of a-IGZO thin film by this new deposition method. We deposited a-IGZO thin films by MFSS on SiO2/p-Si and glass substrate at various process conditions, after which we investigated the morphology, optical and electrical properties of the a-IGZO thin films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.50-53
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• 1992

The GaP crystals are growth by Synthesis Solute Diffusion(SSD) method and its properties are investigated. Etch pits density along vertical direction of ingot is increased from 3.8${\times}$10$^4$cm$\^$-2/ of first freeze to 2.3${\times}$10$\^$5/cm$\^$-2/ of last freeze part. The carrier concentration and mobilities are measured to 197.49$\textrm{cm}^2$/V. sec and 6.75${\times}$10$\^$15/cm$\^$-3/ at room temperature. The temperature dependence of optical energy gap is empilically fitted to E$\_$g/(T)=2.3383-(6.082${\times}$10$\^$-4/T${\times}$/(373.096+T)[eV]. Photo-luminescence spectra measured at low temperature are consist with sharp line-spectra near band-gap energy and radiative recombination between shallow Si-donor to Zn-acceptor and its phonon reprica, and broad emission. The infrared absorption in GaP is cause to phonon coupling modes of TO, LO, LA, TA$_1$, TA$_2$and vibration modes of Ga$_2$O, Si-donor and Zn-acceptor, respectively.

• Microbiology and Biotechnology Letters
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• v.17 no.1
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• pp.35-45
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• 1989

Streptococcus thermophilus 510 was investigated as n potential source of $\beta$-galactosidase. Optimum cultural conditions for maximum enzyme production were 0.5% loctose as carbon source, initial pH 7.0, 37 $^{\circ}C$, and 18 hours of cultivation. The enzyme was purified to homogeneity by ammonium sulfate fractionation, protamine sulfate precipitation, Sephadex G-200 gel filtration, and DEAE-Sephadex A-50 ion exchange chromntography. The purified enzyme exhibited an optimum pH at 1.0, and an optimum temperature of 5$0^{\circ}C$. Metal ions such as Mn$^{2+}$ and $K^+$, dithiothreitol, and 2-mercaptoethanol stimulated $\beta$-galactosidase activity. Ethylenediamine tetraacetic add, 8-hydroxyquinoline, Hg$^2+$, Zn$^{2+}$, Co$^{2+}$, $Ca^{2+}$, and galactose were inhibitory. The $K_m$ and V$_{max}$ for o-nitrophenyl $\beta$-D-galactopyranoside were 1.25mM and 88.50$\mu$moles/min.mg protein, respectively. The molecular weight was estimated to be 520,000, and the amino acid composition indicated relatively high contents of glutamic acid, aspartic acid, leucine, and valine.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.745-764
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• 2023

In the Republic of Congo, Banded iron formations (BIFs) occur in two areas: the Chaillu Massif and the Ivindo Basement Complex, which are segments of the Archean Congo craton outcropping in the northwestern and southwestern parts of the country. They show interesting potential with significant mineral resources reaching 2 Bt and grades up to 60% Fe. BIFs consist mostly of oxide-rich facies (hematite/magnetite), but carbonate-rich facies are also highlighted. They are found across the country within the similar geological sequences composed of amphibolites, gneisses and greenschists. The Post-Archean Australian Shale (PAAS)-normalized patterns of BIFs show enrichment in elements such as SiO₂, Fe₂O₃, CaO, P₂O₅, Cr, Cu, Zn, Nb, Hf, U and depletion in TiO₂, Al₂O₃, MgO, Na₂O, K₂O, Sc, Th, Ba, Zr, Rb, Ni, V. REE diagrams show slight light REEs (rare earth elements; LREEs) compared to heavy REEs (HREEs), and positive La and Eu anomalies. The lithological associations, as well as the very high (Eu/Eu^*)_SN ratios> 1.8 shown by the BIFs, suggest that they are related to Algoma-type BIFs. The positive correlations between Zr and TiO₂, Al₂O₃, Hf suggest that the contamination comes mainly from felsic rocks, while the absence of correlations between MgO and Cr, Ni argues for negligeable contributions from mafic sources. Pr/Pr^* vs. Ce/Ce^* diagram indicates that the Congolese BIFs were formed in basins with redox heterogeneity, which varies from suboxic to anoxic and from oxic to anoxic conditions. They were formed through hydrothermal vents in the seawater, with relatively low proportions of detrital inputs derived from igneous sources through continental weathering. Some Congolese BIFs show high contents in Cr, Ni and Cu, which suggest that iron (Fe) and silicon (Si) have been leached through hydrothermal processes associated with submarine volcanism. We discussed their tectonic setting and depositional environment and proposed that they were deposited in extensional back-arc basins, which also recorded hydrothermal vent fluids.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1158-1167
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• 2000

To produce ${\beta}-cyclodextrin({\beta}-CD)$, a cyclodextrin glucanotransferase(CGTase) producing Aspergillus sp. CC-2-1 was isolated from soil. The enzyme was purified and its enzymological characteristics were investigated. It was found that production of CGTase reached to the maximum when the wheat bran medium containing 0.1% albumin, 2% $(NH_4)_2S_2O_8$, 2% soluble starch and 0.2% $KH_2PO_4$ was cultured for 5 days at $37^{\circ}C$. The purity of CGTase was increased by 13.14 folds after DEAE-cellulose ion exchange chromatography and Sephadex G-100, G-150 gel filtration and the specific activity was 172.14 unit/mg. Purified enzyme was confirmed as a single band by the polyacrylamide gel electrophoresis. The molecular weight of CGTase was estimated to be 27,800 by Sephadex G-100 gel filtration and SDS-polyacrylamide gel electrophoresis. The optimum pH and temperature for the CGTase activity were 9.0 and $80^{\circ}C$, respectively. The enzyme was stable in pH $8.0{\sim}11.0$ at $60{\sim}80^{\circ}C$. The activity of purified enzyme was activated by $K^+,\;Cu^{2+}$ and $Zn^{2+}$. The activity of the CGTase was inhibited by the treatment with 2,4-dinitrophenol and iodine. The result suggests that the purified enzyme has phenolic hydroxyl group of tyrosine, histidine imidazole group and terminal amino group at active site. The reaction of this enzyme followed typical Michaelis-Menten kinetics with the $K_m$ value of 18.182 g/L with the $V_{max}$ of 188.68 ${\mu}mole/min$. The activation energy for the CGTase was calculated by Arrhenius equation was 1.548 kcal/mol.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.97.1-97.1
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• 2010

유연금속기판위에 DC 마그네트론 스퍼터링을 이용하여 Ag/ZnO 이중구조의 후면반사막을 증착하고 Ag 표면조도 변화에 따른 후면반사막의 반사특성 변화와 플렉서블 비정질 실리콘 박막 태양전지의 셀 특성에 미치는 영향을 조사하였다. Substrate구조를 갖는 플렉서블 실리콘 박막 태양전지에서는 실리콘 박막 광흡수층의 상대적으로 낮은 광 흡수율로 인하여 입사광에 대한 태양전지 내에서의 광 산란 및 포획이 태양전지 효율을 증대시키는데 매우 중요한 역할을 하는 것으로 알려져 있다. 플렉서블 실리콘 박막 태양전지에서의 후면반사막은 광 흡수층에서 흡수되지 않는 입사광을 다시 반사시켜 광 흡수를 증대시키며 이때 후면반사막 표면에서 반사 빛을 효율적으로 산란시켜 이동경로를 증대시킴으로써 광 흡수율을 더욱 향상시킬 수 있다. 본 연구에서는 유연금속 기판위에 Ag와 ZnO:Al($Al_2O_3$ 2.5wt%) 타겟을 사용한 DC 마그네트론 스퍼터링법으로 Ag/AZO 이중구조의 후면반사막을 제조하고, Ag 박막의 표면형상 변화와 이에 따른 후면반사막의 반사도 변화를 비교, 분석하였다. 증착 조건 변화에 따른 표면 형상 및 반사 특성은 Atomic Force Mircroscope(AFM), Scanning electron miroscopy(SEM), UV-visible-nIR spectrometry를 통하여 분석하였다. 서로 다른 표면 거칠기를 갖는 후면반사막 위에 n-i-p구조의 a-Si:H 실리콘 박막 태양전지를 제조한 후 태양전지 동작 특성에 미치는 영향을 조사하였다. n,p층은 13.56MHz PECVD, i층은 60MHz VHF CVD를 사용하여 각각 제조 하였으며, Photo I-V, External Quantum Efficiency(EQE) 분석을 통하여 태양전지 특성을 조사 하였다. SEM 분석결과 공정 온도가 증가 할수록 Ag 박막의 표면 결정립 크기도 증가하였으며, AFM분석을 통한 Root-mean-square(Rms)값은 상온에서 $500^{\circ}C$로 증착온도가 증가함에 따라 6.62nm에서 46.64nm까지 증가하였다. Ag 박막의 표면 거칠기 증가에 따라 후면반 사막의 확산 반사도도 함께 증가하였다. 공정온도 $500^{\circ}C$에서 증착된 후면반사막을 사용하여 a-Si:H 태양전지를 제조하였을 때 상온에서 제조한 후면반사막에 비하여 단락전류밀도 (Jsc)값은 9.94mA/$cm^2$에서 13.36mA/$cm^2$로 증가하였으며, 7.6%의 가장 높은 태양전지 효율을 나타내었다.