• Korean Journal of Materials Research
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• v.16 no.2
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• pp.80-84
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• 2006

The removal efficiency of Cu and Fe contaminants on the silicon wafer surface was examined to investigate the effect of cleaning solutions on the behavior of metallic impurities. Silicon wafers were intentionally contaminated with Cu and Fe solutions by spin coating and cleaned in different types of cleaning solutions based on $NH_4OH/H_2O_2/H_2O\;(SC1),\;H_2O_2/HCl/H_2O$ (SC2), and/or HCl/$H_2O$ (m-SC2) mixtures. The concentration of metallic contaminants on the silicon wafer surface before and after cleaning was analyzed by vapor phase decomposition/inductively coupled plasma-mass spectrometry (VPD/ICP-MS). Cu ions were effectively removed both in alkali (SC1) and in acid (SC2) based solutions. When $H_2O_2$ was not added to SC2 solution like m-SC2, the removal efficiency of Cu impurities was decreased drastically. The efficiency of Cu ions in SC1 was not changed by increasing cleaning temperature. Fe ions were soluble only in acid solution like SC2 or m-SC2 solution. The removal efficiencies of Fe ions in acid solutions were enhanced by increasing cleaning temperature. It is found that the behavior of metallic contaminants as Cu and Fe from silicon surfaces in cleaning solutions could be explained in terms of Pourbaix diagram.

• YAKHAK HOEJI
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• v.9 no.1_2
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• pp.18-22
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• 1965

A new organic reagent, 1-isonicotinoyl-2-furfurylidene hydrazine was synthesized from isonicotinic acid hydrazide and furfural, gives precipitate with copper(II), mercury(II) and argent(I), whereas, it gives a water soluble yellow complex with iron(III). Copper complex of the reagent is soluble in EtOH MtOH, pyridine, dioxane and dimethylformamide with green yellow coloration. The complex has a maximum absorption at 385 m.$\mu$ and molar ratio of copper; reagent was estimated as 1:1 by continuous variation method, slop method and chelate titration method. Molar extinction coefficient (9600) and apparant formation constant of this complex was spectrophotometrically determined. K=1.7 * $10^{7}$ (Babko's method) K=2.1 * $10^{7}$ (Anderson's method). This reagent reacted with copper so sensitive that it would be available for determination of Cu (II).

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.141-146
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• 2014

A series of bimetallic Cu-Zn/$SiO_2$ catalysts were prepared via thermal decomposition of the as-synthesized $CuZn(OH)_4(H_2SiO_3)_2{\cdot}nH_2O$ hydroxides precursors. This highly dispersed Cu-solid base catalyst is extremely effective for hydrogenation of ethyl acetate to ethanol. The reduction and oxidation features of the precursors prepared by coprecipitation method and catalysts were extensively investigated by TGA, XRD, TPR and $N_2$-adsorption techniques. Catalytic activity by ethyl acetate hydrogenation of reaction temperatures between 120 and $300^{\circ}C$, different catalyst calcination and reduction temperatures, different Cu/Zn loadings have been examined extensively. The relation between the performance for hydrogenation of ethyl acetate and the structure of the Cu-solid base catalysts with Zn loading were discussed. The detected conversion of ethyl acetate reached 81.6% with a 93.8% selectivity of ethanol. This investigation of the Cu-Zn/$SiO_2$ catalyst provides a recently proposed pathway for ethyl acetate hydrogenation reaction to produce ethanol over Cu-solid base catalysts.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.4
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• pp.235-240
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• 2017

The effect of particle sizes on the aerosol deposition (AD) of Cu films is investigated in order to understand the deposition behaviors of metal powder during the AD process. The Cu coatings fabricated by using $2{\mu}m$ Cu powders had a dense microstructure, a high deposition rate ($1.6{\pm}0.2{\mu}m/min$), and low resistance ($9.42{\pm}0.4{\mu}{\Omega}{\cdot}cm$) compared to that from using Cu powder with a particle size greater than $5{\mu}m$. Also, from estimating the internal micro-strain of Cu films, the Cu coatings fabricated by using $2{\mu}m$ Cu particles exhibited a high micro-strain value of $3.307{\times}10^{-3}$. On the other hand, the strain of Cu coatings fabricated with $5{\mu}m$ particles was decreased to $2.76{\times}10^{-3}$. These results seem to show that the impacted Cu particles are compressed and flattened by shock waves, and that their bonding is associated with the high internal micro-strain caused by plastic deformation.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.46-55
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• 1999

This study compared the adsorption characteristics of heavy metal ions by crab shell, treated crab shell with 2N-HCl, treated crab shell with 4%-NaOH, chitin and chitosan.Using crushed crab shell, the heavy metal ions removal rates of $Cd^{2+}$ and $Zn^{2+}$ were about 70-80% in 45minutes, but the removal rates of $Cu^{2+}$, $Cr^{6+}$ and $Pb^{2+}$ was less than 10%, 10% and 30%, respectively. For the by-products crab shell by 2N-HCl treatment, it was shown that the removal rates of $Cu^{2+}$ and $Pb^{2+}$ were about 70-80% in 45minutes reaction. But, some problems were observed, that the contained protein in crab shell was changed into gel in the mixing solution after a few hours. For the by-products of crab shell by 4%-NaOH treatment, the removal rates of Pb and Zn were about 90% in 45 minutes, and those of capacity of chitin and chitosan powder was better than those of the other by-products. The more adding to the adsorbent dosages increased the removal rates, and the adsorption reaction was rapidly occurred in a few minute. Using 1.0 wt% chitin powder, the heavy metal removal rates were ordered $Cu^{2+}$(94%) > $Zn^{2+}$(89%) > $Cd^{2+}$(88%) > $Pb^{2+}$(77%) > $Cr^{6+}$(58%) in 45 minutes. Using 1.0 wt% chitosan powder, the heavy metal removal rates were ordered $Cu^{2+}$(99%) > $Pb^{2+}$(96%) > $Cd^{2+}$(79%) > $Zn^{2+}$(71%) > $Cr${6+}$(46%) in 45minutes. The degree of degree of deacetylation by prepared chitosan was 91%.The Freundlich adsorption isotherm of $Cu^{2+}$, $Cd^{2+}$ and $Zn^{2+}$, when it was applied to 1.0 wt% chitosan powder in minutes, can be acceptable very strictly. The equation constant (1/n) for $Cu^{2+}$, $Cd^{2+}$ and $Zn^{2+}$ were 0.54 0.41 and 0.23 respectively.

• Polymer(Korea)
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• v.39 no.2
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• pp.235-239
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• 2015

In this work, we evaluated catalytic activity of LiOH, $Cu(acac)_2$ and n-butyltin hydroxide oxide hydrate in the early stage of the melt transesterification of isosorbide and bisphenol A as diol monomers and diphenylcarbonate for the melt polymerizaiton of polycarbonate. $Cu(acac)_2$ proved to be the most active catalyst for homopolymerization process, while the catalytic activity of LiOH was higher than the others in case of melt copolymerization depending on the catalytic mechanism and chemical structure of catalyst. We suggested that evaluation of catalytic activity can be used for selection of catalyst system in bio-based copolymerization of polycarbonate.

• 보존과학연구
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• s.24
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• pp.131-152
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• 2003

In ancient times, many kinds of different inorganic pigments were used as colorants for making objects. These pigments are still evidentin well known objects such as Danchung, mural painting and Buddhist painting. This study discusses the results obtained from an analysis of the pigments used on the Buddha pigments. The results can be briefly summarized as below; Firstly, the microcrystalline structures revealed on the cross section of analyzed pigments, samples of which were taken from various parts of Buddha pigments show that different sizes and shapes of pigment particle were used for different purposes such as coloring, toning of the pigments. The arrangement of pigments and their usages are varied according to the owner temples and the place where it was created. Secondly, a result of the analysis on the composition and structure of the pigments shows that the main components in their composition are: Red pigments - Red lead($Pb_3O_4$) and Cinnabar(HgS)Green pigments - Malachite[$CuCO_3$.$Cu(OH)_2$] and Prussian Blue[$Fe4(Fe(CN)_6)_2$]Gold pigments - pure gold(Au)Yellow pigments - Orpiment($A_s2S_3)White pigments - Lead Cyanamide[$Pb_3(CO_3)_2(OH)_2]Ultramarine pigments - Azulite[$Cu_3(CO_3)_2(OH)_2]Especially, we knew that pigments used on the Ssanggye temple not repaired to the artificial synthetic pigment

• 보존과학연구
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• s.28
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• pp.121-147
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• 2007

A large variety of mineral pigments has been used for Korean paintings and it has known that organic pigments have been used together on the Buddhist painting and the portrait. Haehakbando-do, which is from Honolulu Academy Museum in the United States, 12-fold screen was commissioned by Court of the late Joseon Dynasty in order to pray for the King's longevity. Therefore, it seems that all material used including pigments were selected very carefully and a great deal of technical effort was gone into its process. The purposes of this research were to estimate the pigments and the contributory elements of each color used on Haehakbando-do, in accordance with the conservation treatment carried out by Gochang Conservation Institute throughout last year. Without extracting sample, property of pigment was measured by nondestructive method, X-ray spectral analysis, and by comparing with the data about ancient pigments. In spite of the limited range of pigment analysis by nondestructive method, it should be noted that this method would not cause damage to the cultural properites. White pigment was found in all colored parts except the background, so it can be suggested that white color was used as a grounding of other color pigments. This would be flake white[$2PbCO_3{\cdot}Pb(OH)_2$] as Pb was found. Pb was the only element could be found in yellow, however, it can be organic pigment like Gamboge as same as background. Red would be Cinnabar (HgS) as hydrargyrum (Hg) was detected. For the light purple in cloud, organic pigments were probably used since any element is not detected except for Pb, which is used for background. It is possible that green color is the mixture of Malachite[$CuCO_3{\cdot}Cu(OH)_2$] and Azurite [$2CuCO_3{\cdot}Cu(OH)_2$], which share Cu as their main element. Azurite[$2CuCO_3{\cdot}Cu(OH)_2$] was used for bluish pigments. Black is carbon compound. For gold, solid gold (Au) was detected. It shows that gold was gilded on the flake white background. Red painted on the frame of screen was identified as Cinnabar (HgS) and the gold pattern was solid gold (Au). The supporting leg of folding screen was made of brass because both copper and zinc were detected. In conclusion, white pigment was used as grounding of all colors of Haehakbando-do, and specific pigments were used for each color. Additionally, result from the analysis of several pigments shows that mineral pigment and organic pigment, or different mineral pigments were mixed to make various colors.

• Journal of Powder Materials
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• v.16 no.4
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• pp.280-284
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• 2009

The pressureless sintering behavior of $Al_2O_3$/Cu powder mixtures, prepared from $Al_2O_3$/CuO and $Al_2O_3$/Cu-nitrate, has been investigated. Microstructural observation revealed that $Al_2O_3$ powders with nano-sized Cu particles could be synthesized by hydrogen reduction method. The specimens, pressureless-sintered at $1400^{\circ}C$ for 4 min using infrared heating furnace with the heating rate of $200^{\circ}C$/min, showed the relative density of above 90%. Maximum hardness of 16.1 GPa was obtained in $Al_2O_3$/MgO/Cu nanocomposites. The nanocomposites exhibited the enhanced fracture toughness of 4.3-5.7 $MPa{\cdot}m^{1/2}$, compared with monolithic $Al_2O_3$. The mechanical properties were discussed in terms of microstructural characteristics.

• Economic and Environmental Geology
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• v.52 no.6
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• pp.529-539
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• 2019

In this study, heavy metal removal and precipitation characteristics with pH change were studied for artificial acid mine drainage. Artificial acid mine drainage was prepared using sulfates of iron, aluminum, copper, zinc, manganese which contained in acid mine drainage from abandoned mines. The single and mixed five heavy metal samples of Fe, Al, Cu, Zn, and Mn were prepared at initial concentrations of 30 and 70 mg/L. Fe and Al were mostly removed at pH 4.0 and 5.0, respectively, and other heavy metals gradually decreased with increasing pH. Concentration changes with increasing pH show generally similar trend for single and mixed heavy metal samples. The effect of removing heavy metals from aqueous solutions is not related to the initial concentration and depends on the pH change. XRD were used for mineral identification of precipitates and crystallinity of the mineral tended to increase with increasing pH. The precipitates that produced by decreasing the concentration of heavy metals in the aqueous solution composed of Fe-goethite(FeOOH), Al-basaluminite(Al₄(SO₄)(OH)₁₀·4H₂O), Cu-connellite(Cu₁₉(OH)₃₂(SO₄)Cl₄·3H₂O) and tenorite(CuO), Zn-zincite(ZnO), and Mn-hausmannite(Mn₃O₄).