• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.140-144
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• 2012

Ga-doped ZnO (GZO) was a limit of application on the photovoltaic devices such as CIGS, CdTe and DSSC requiring high process temperature, because it's electrical resistivity is unstable above 300 ℃ at atmosphere. Therefore, ZTO (zinc tin oxide) was introduced in order to improve permeability and thermal stability of GZO film. The resistivity of GZO (300 nm) single layer increased remarkably from 1.8 × 10-3Ωcm to 5.5 × 10-1Ωcm, when GZO was post-annealed at 400 ℃ in air atmosphere. In the case of the ZTO (150 nm)/GZO (150 nm) double layer, resistivity showed relatively small change from 3.1 × 10-3Ωcm (RT) to 1.2 × 10-2Ωcm (400 ℃), which showed good agreement with change of carrier density. This result means that ZTO upper layer act as a barrier for oxygen at high temperature. Also ZTO (150 nm)/GZO (150 nm) double layer showed lower WVTR compared to GZO (300 nm) single layer. Because ZTO has lower WVTR compared to GZO, ZTO thin film acts as a barrier by preventing oxygen and water molecules to penetrate on top of GZO thin film.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.98-103
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• 2001

In order to understand the characteristics of leachate at the Seokdae municipal waste landfill in the Pusan city, the correlation between leachate pollution loading and volume of gas production. concentration of gas and subsidence of ground, the characteristical methos, geochemical analyses and laboratory column tests using samples of gases, leachate and surface soil of Seokdae waste landfill area. Through the analysis of water balance, leachate flow rate and pollution loading were estimated. Geistatistical analysis of four gas components ( $O_2$, C $H_4$, $H_2$S and CO) shows the possibility of ground subsidence around the group of a site with high concentration of gas. From geochemical analyses of leachate, EC and Total-Alkalinity of ground subsidence around the group of a site with high concentration of gas. From geochemical analysis of leachate, Ec and Total-Alkalinity were increased, and Cl, Cr, Mn, Cu, Zn, Cd and Pb were decreassed comparing to the part, and the type of water quality was Na-HC $O_3$ in trilinear diagram. It shows that biodecomposition of municipal wastes continues actively. From the analysis of water balance, the total leachate flow rate is about 465.11㎥/day and pure pollution loading of Cl, Mn and Fe are estimated to 223.8kg/day, 0.2kg/day, 0.3kg/day, respectively. The laboratory column test of residual soil and landfill soil shows 0.206cm and 0.019cm for linear velocity(equation omitted), 0.234 $\textrm{cm}^2$/min and 0.018$\textrm{cm}^2$/min for diffusion coefficient ( $D_{ι}$), and 1.136cm and 0.095cm longitudinal dispersion index ($\alpha$$_{ι}$), respective]y. It demonstrates that the delay time of contamination for residual soil is shorter than that of landfill soil.

• Economic and Environmental Geology
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• v.36 no.4
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• pp.285-293
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• 2003

Tailings of Dukum mine in the vadose and saturated zone were investigated to reveal the mobility of metal elements and the condition of mineralogical solubility according to redox environments throughout the geochemical analysis, thermodynamic modelling, and mineralogical study for solid-samples and water samples(vadose zone; distilled water: tailings=5 : 1 reacted, saturated zone; pore-water extracted). In the vadose zone, sulfide oxidation has generated low-pH(2.72∼6.91) condition and high concentration levels of S $O_4$$^{2-}$(561∼1430mg/L) and other metals(Zn : 0.12∼l57 mg/L, Pb : 0.06∼0.83 mg/L, Cd : 0.06∼l.35 mg/L). Jarosite$(KFe_3(SO_4)_2(OH)_6)$ and gypsum$(CaSO_4{\cdot}2H_2O$) were identified on XRD patterns and thermodynamics modelling. In the saturated zone, concentration of metal ions decreased because pH values were neutral(7.25∼8.10). But Fe and Mn susceptible to redox potential increased by low-pe values(7.40∼3.40) as the depth increased. Rhodochrosite$(MnCO_3)$ identified by XRD and thermodynamics modelling suggested that $Mn^{4+}$ or $Mn^{3+}$ was reduced to $Mn^{2+}$. Along pH conditions, concentrations of dissolved metal ions has been most abundant in vadose zone throughout borehole samples. It was observed that pH had more effect on metal solubilities than redox potential. How-ever, the release of co-precipitated heavy metals following the dissolution of Fe-Mn oxyhydroxides could be the mechanism by which reduced condition affected heavy metal solubility considering the decrease of pe as depth increased in tile saturated zone.

• Korean Journal of Microbiology
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• v.30 no.5
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• pp.391-396
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• 1992

Anabaena variabilis A TCC 29413. a photoautotrophic and nitrogen fixing cyanobacteria. was investigated on the environmental factors regulating the growth and nitrogen lixation activity. A good growth of cyanobacteria] cells was observed due to nitrogen t1xation by the heterocyst differentiation in nitrogen free Allen and Arnon (]/8) medium. The nitrogenase activity was appeared to be in proportion to the cell growth lor 6 days then drastically decreased in the later growth period when the nitraTe was accumulated to high level in the culture to cause the inhibition. The optima] conditions lilr the cell growth and nitrogenase activity of A. varillbili.l were anaerobic. IO.OO0 lux. $30^{\circ}C$ and pH 8 with the nitrogen Cree minimal medium. The activity was significantly inhihited by the low concentrations of ammonium and nitrate. but was stimulated b) the ]ow Ieve] of phosphate and carbonate sources. The treatments of several toxic heavy metals showed strong inhibition of the cell growth and nitrogenase activity by O.3~10 ppm in the order of $Hg^{2+}$ > $Cd^{2+}$ > $Co^{2+}$ > $Zn^{2+}$ > $Ph^{2+}$, and the concentrations for 50% inhibition of the maximum activity were 0.41. 0.47. 0.5 L 0.66 and 8.1 ppm. respectively. The addition of carbohydrates (0.5~ 1.0%) in the dark condition stimulated the growth and activity in the order of sucrose > fructose > glucose.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.245-245
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• 2015

Cu(In,Ga)Se2 (CIGS) 박막 태양전지는 높은 효율과 낮은 제조비용, 높은 신뢰성으로 인해 박막 태양전지 중 가장 각광받고 있다. 특히 유리기판 대신 가볍고 유연한 철강소재나 플라스틱 소재를 이용하여 발전분야 외에 건물일체형, 수송용, 휴대용등 다양한 분야에 적용이 가능하다. 이러한 유연 기판을 이용한 CIGS 태양전지의 개발을 위해서는 기판의 특성에 따른 다양한 공정개발이 선행되어야 한다. 특히 CIGS 태양전지에서는 Na의 역할이 매우 중요한데 유연기판의 경우 이러한 Na이 없을 뿐만 아니라 철강기판의 경우 Fe, Ni, Cr등의 불순물이 확산되어 흡수층의 특성을 저하시켜 효율을 감소시킨다. 따라서 이러한 철강 기판의 경우 불순물의 확산을 방지하는 확산방지막이 필수적이다. 또한 플라스틱기판의 경우 내열성이 낮아 저온에서 공정을 진행해야하는 단점이 있다. 이러한 유연기판의 특성을 고려하여 본 연구에서는 유연기판으로 STS 430 stainless steel과 poly-imide를 이용하여 특성 개선을 진행하였다. 먼저 stainless steel과 Poly-imide, soda-lime glass, coning glass의 기판을 이용하여 기판에 따른 흡수층의 특성을 비교 분석하였으며 stainless steel 기판을 이용하여 확산 방지막의 유무 및 두께에 따른 흡수층 및 소자의 특성을 분석하였다. 이때 확산 방지막은 기존 TCO 공정에서 사용되는 i-ZnO를 사용하였으며 RF sputter를 이용하여 50~200nm로 두께를 달리하며 특성 비교를 실시하였다. 이때 효율은 확산방지막을 적용하지 않았을 때 약 5.9%에서 확산 방지막 적용시 약 10.6%로 증가하였다. 또한 poly-imide 기판을 이용하여 $400^{\circ}C$이하에서 흡수층을 제조하여 특성평가를 진행하였으며 소자 제조 후 효율은 약 12.2%를 달성하였다. 모든 흡수층은 Co-Evaporation 방법을 이용하여 제조하였으며 제조된 흡수층은 SEM, XRF, XRD, GD-OES, PL, Raman등을 이용하여 분석하였으며 그 외 일반적인 방법을 이용하여 Mo, CdS, TCO, Al grid를 제조하였다. AR 코팅은 제외 하였으며 제조된 소자는 솔라 시뮬레이터를 이용하여 효율 특성 분석을 실시하였으며 Q.E. 분석을 실시하였다.

• Journal of the Korean Chemical Society
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• v.12 no.1
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• pp.4-11
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• 1968

With the selected emulsifiers for the emulsion polymerization of methyl methacrylate, the HLB of the emulsifier in the reaction system has been studied on the effect of the ratio of tetra sodium-N-(1,2-dicarboxy ethyl)-N-octadecyl sulfosuccinamate(Aerosol 22) to polyethylene glycol nonyl phenyl ether (Noigen EA 160), and also sodium lauryl sulfate(Quolac EX-UB), Disodium-N-octadecyl sulfosuccinamate (Aerosol 18) and Aerosol 22 as emulsifiers having various hydrophilic groups in the molecules have been studied. Results are as follows; 1) The viscosity of the emulsions and the molecular weight of the polymers have maximum values at a constant HLB value of emulsifiers, but their stabilities show minimum point at the value with the titration with the three kinds of mono, bi, tri-valent electrolytes. These results are agreed on the theory of Greth & Wilson in which the properties of polymer emulsions depend upon the HLB system of emulsifiers. 2) The viscosity of the emulsions and the molecular weights of the produced polymers increase more in the case of blending of Aerosol 22 to Noigen EA-160 than of the separate using. 3) The coagulation effects of the divalent electrolytes($ex,\;Ca^{++},\;Zn^{++}$) are contrast to the effects of monovalent($ex,\;Na^+$) and trivalent($ex,\;Al^{+++}$) in the emulsions with Aerosol 18 or Aerosol 22 which have more than two hydrophilic groups. It seems that the stability of the O/W emulsions by electrolytes is directly related to the parameters of surface physical chemistry such as surface geometry of surface chemical constitution of polymer particles.

• Current Research on Agriculture and Life Sciences
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• v.14
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• pp.111-122
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• 1996

S. chibaensis J-59 produced an extracellular xylanase in a CSL medium composed of 1.5% com steep liquor, 0.1% $MgSO_4{\cdot}7H_2O$, 0.012% $CoCl_2{\cdot}6H_2O$, and 0.15% glucose containing xylan. but it did not produce in the culture medium containing xylose. The production of enzyme reached to a maximum level (0.83 uints/ml) when bacteria were cultured in 2.5 l jar fermentor for 48hrs at $30^{\circ}C$ and pH 7.0. Furthermore, S. chibaensis J-59 produced an intracellular glucose isomerase in a medium containing xylan and/or xylose. Xylanase was purified 29-fold over the culture supernatants of S. chibaensis J-59 by ammonium sulfate fractionation, chromatography on DEAE-Sephadex A-50, and gel filtration on Sephadex G-200. The purified enzyme is a monomeric enzyme with a native molecular mass of 25 kDa and a subunit molecular mass of 25 kDa. The purified enzyme requires $Mg^{2+}$ for activity, $Ca^{2+}$, $Co^{2+}$ is not an inhibitor but inhibit by $Fe^{3+}$, $Hg^{2+}$, and $Cu^{2+}$, sodium dodecyl sulfate, N-bromosuccinide. Pattern of hydrolysis demonstrated that the xylanase was an endo-splitting enzyme able to break down birchwood xylan at random giving xylobiose, xylotriose and xylotetrose as the main end products.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.21-27
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• 2011

The comparison work was conducted for the methanol steam reforming among commercial Cu-based catalysts, viz. ICI-M45, which is for the methanol synthesis, MDC-3 and MDC-7, which are for the water-gas shift reaction. The catalytic activity for the water-gas shift reaction was also compared over three catalysts. Among them, MDC-7 showed the highest methanol conversion and formation rate of hydrogen and carbon dioxide at 473 K for the methanol steam reforming. To find out any promotional effect between ICI-M45 and MDC-7, three different packing methods with these two catalysts were examined. However, no synergistic effect was observed. The catalytic activity for watergas shift reaction decreased in the following order: MDC-7 > MDC-3 > ICI-M45. The highest activity of MDC-7 for the methanol steam reforming as well as the water-gas shift reaction can be due to its high surface area, copper dispersion, and an adequate Cu/Zn ratio.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.2
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• pp.85-93
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• 2013

This study has been carried out to elucidate the characteristics of the dissolution for Thermal Decomposed Solid Waste of uranium-bearing sludge (TDSW), the removal of impurities by an alkalization in a nitric acid dissolving solution of TDSW, and the selective removal (/recovery) of uranium by an acidification in an carbonate alkali solution, respectively. TDSW generated by thermal decomposition of U-bearing sludge which was produced in the uranium conversion plant operation, was stored in KAERI as a solid-powder type. It is found that the dissolution of TDSW is more effective in nitric acid dissolution than oxidative-dissolution with carbonate. At 1 M nitric acid solution, TDSW was undissolved about 30wt% as a solid residue, and uranium contained in TDSW was dissolved more than 99%. In order to the alkalization for the nitric acid dissolving solution of TDSW, carbonate alkalization is more effective with respect to remove the impurities. At the carbonate alkali solution controlled to about 9 of pH, Al, Ca, Fe and Zn co-dissolved with U in dissolution step was removed about $98{\pm}1%$. On the other hand, U could be recovered more than 99% by an acidification at pH about 3 in a carbonate alkali solution, which was nearly removed the impurities, adding 0.5M $H_2O_2$. It was found that uranium could be selectively recovered (/removed) from TDSW.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.2
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• pp.231-237
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• 2006

The extracellular enzyme alginase produced by Bacillus licheniformis AL-577 was purified by ion chromatography on CM-Cellulose column, DEAE-Sepharose column, and followed by gel filtration on Sephadx G-100 column. The optimum pH and temperature for the activity of the purified enzyme were 6.0 and $35^{\circ}C$, respectively. The enzyme was stable at the pH range of $6.0\~9.0$ and at $20^{\circ}C$. The molecular weight of the enzyme was estimated to be about 25,500 daltons by SDS-polyacrylamide gel electrophoresis. NaCl was required for high activity of the enzyme. The enzyme was inhibited by $Ba^{2+},\;Co^{2+},\;Cu^{2+},\;Fe^{2+},\;Mg^{2+},\;Zn^{2+},\;NH_4^+$, EDTA, L-cysteine, and 2-mercaptoethanol, while stimulated by DTT, O-phenanthroline, $K^+$ and $Li^+$. This enzyme was proposed to be an alginase specifically degrading alginic acid.