• Resources Recycling
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• v.23 no.1
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• pp.33-39
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• 2014

In this study, the solubility of Cu, which is a main metal component of wasted PCB, in $CaO-SiO_2-Al_2O_3-MgO$ slag system was investigated. Each 20 grams of Cu chips and the quaternary slag manufactured was placed in an carbon crucible and melted for 10 hours in the temperature between 1673 K and 1825 K to confirm the equilibrium state. The oxygen partial pressure was controlled by the ratio of CO and Ar gas in the range of $10^{-17.23}$ to $10^{-15.83}$ atm. The concentration of Cu in the slag increased with increasing oxygen partial pressure, slag basicity, and MgO content in the slag. The concentration of Cu in the slag decreased with increasing temperature. The Cu dissolution reaction in the slag is an exothermic reaction.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.440-440
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• 2012

Nanomaterials have emerged as new building blocks to construct light energy harvesting assemblies. Size dependent properties provide the basis for developing new and effective systems with semiconductor nanoparticles, quantized charging effects in metal nanoparticle or their combinations in 2 and 3 dimensions for expanding the possibility of developing new strategies for photovoltaic system. As top-down approach, we developed a simple and effective method for the large scale formation of self-assembled Cu(In,Ga)$Se_2$ (CIGS) nanostructures by ion beam irradiation. The compositional changes and morphological evolution were observed as a function of the irradiation time. As the ion irradiation time increased, the nano-dots were transformed into a nano-ridge structure due to the difference in the sputtering yields and diffusion rates of each element and the competition between sputtering and diffusion processes during irradiation. As bottom-up approach, we developed the growth of CIGS nanowires using thermal-chemical vapor deposition (CVD) method. Vapor-phase synthesis is probably the most extensively explored approach to the formation of 1D nanostructures such as whiskers, nanorods, and nanowires. However, unlike binary or ternary chalcogenides, the synthesis of quaternary CIGS nanostructures is challenging because of the difficulty in controlling the stoichiometry and phase structure. We introduced a method for synthesis of the single crystalline CIGS nanowires in the form of chalcopyrite using thermal-CVD without catalyst. It was confirmed that the CIGS nanowires are epitaxially grown on a sapphire substrate, having a length ranged from 3 to 100 micrometers and a diameter from 30 to 500 nm.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.4
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• pp.244-252
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• 1994

The morphological changes of primary solid particles as a fuction of process time on Al-Si alloys during semi-solid state processing with a shear rate of 200s were studied. In hypereutectic Al-15.5wt%Si alloy, it was observed that primary Si crystals are fragmented in the early stage of stirring and morphologies of primary Si crystals change from faceted to spherical during isothermal shearing for 60 minutes. In quaternary Al-12.5wt%Si-2.9wt%Cu-0.7wt%Mg alloy system, it was observed both primary silicon and ${\alpha}$-alumunum particles. Microstructural evolution of primary Si crystals was similar to that of the hypereutectic Al-Si alloy but equiaxed ${\alpha}$-Al dendrites are broken into nearly spherical at the early stage of shearing and later stage of the isothermal shearing ${\alpha}$- Al particles are slightly coarsoned by Ostwald ripening. Mechanical properties of Al-Si-Cu-Mg alloy were compared to those from other processes (squeeze casting and gravity casting). After T6 heat treatment, comparable values of hardness were obtained while slightly lower compressive strength values were observed in rheocast alloy. The elongation, on the other hand, exhibited significant increasement of 15% over gravity cast alloy.

• Analytical Science and Technology
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• v.7 no.1
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• pp.25-31
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• 1994

As for analytes which did not represent the differences of the selectivity on the stationary and mobile phase, secondary chemical equilibrium theory was applied to study pH effects on the separation of alkylphenols. Mobile phase was consisted of an aqueous sodium carbonate-bicarbonate buffer and acetonitrile. The maximum selectivity for adjacent peak pairs was predicted from those values of $k^{\prime}_{HA}/k^{\prime}_{A-}$ and ${\Delta}pK$. The optimum pH determined by this method was 11.18 pH and solvent selectivity were considered at the same time to invoke the full range of selectivity effects possible for separations. Quaternary mixture composed of methanol, acetonitrile, tetrahydrofuran and water was adjusted to optimum pH 11.18. As the statistical simplex technique of an overlapping resolution map (ORM) was used to predict the optimized solvent system. The optimum solvent, which gives complete separation of alkylphenols, was determined as follws MeOH : ACN : THF = 14.4 : 81.8 : 2.8.

• Environmental Analysis Health and Toxicology
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• v.16 no.4
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• pp.223-226
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• 2001

Acetanilide is a High Production Volume Chemical, which is produced about 2,300 tons/year in Korea as of 1998 survey. Most is used as an intermediate for synthesis of pharmaceuticals and dyes. The chemical is one of seven chemicals, which are under the frame of OECD SIDS program sponsored by National Institute of Environmental Research of Korea. Regarding the information on the environmental fate. bioconcentration is one of important factor to estimate the environmental tranfer. However, measurement of bioconcentration needs high expense and time. For this reason, OECD recommends to use BCFWIN model to estimate bioconcentration of organic chemicals, BCFWIN estimates the bioconcentration factor (BCF) of an organic compound using the log octanol-water partition coefficient (Kow) of the compound. Structures are entered into BCFWIN through SMITES (Simplified Molecular Input Line Entry System) notations. The BCFWIN method classifies a compound as either ionic or non-ionic. ionic compounds include carboxylic acids, sulfonic acids and salts of sulfonic acids, and charged nitrogen compounds (nitrogen with a + 5 valence such as quaternary ammonium compounds). All other compounds are classified as non-ionic. In this study, bioaccumulation of acetanilide was estimated using BCFWIN model based on SMIIES notation, chemical name data and partition coefficient as one of environmental fate/distribution of the chemical elements.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2000.05a
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• pp.19-19
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• 2000

;Ultramafic xenoliths found in alkali basalts from Jeju-do, Korea are mostly spinel Iherzolites composed of olivine, orthopyroxene, clinopyroxene and spinel. A subordinate amount of spinel harzburgites and pyroxenites are also found. Temperatures for these xenoliths were estimated from the compositions of coexisting pyroxenes (Wood '||'&'||' Banno 1973; Wells 1977; Bertrand '||'&'||' Mercier 1985; Brey '||'&'||' Kohler 1990), the AI-solubility in orthopyroxene coexisting with olivine and spinel (Sachtleben '||'&'||' Seck 1981; Webb '||'&'||' Wood 1986), and from Fe/Mg partitioning between olivine and spinel (Ballhaus et al. 1991). Temperature estimates from the thermometers by Wells (1977) and Brey and Kohler (1990) are compatible. Average equilibrium temperatures by these two methods for spinel peridotites range from 890 to 1030$^{\circ}$C. Pressures for spinel peridotites were estimated from the geobarometer by Kohler and Brey (1991) derived from the equilibrium Ca content of olivine coexisting with clinopyroxene, and fall within the range of 12.9 to 26.3 kbar. The combination of the thermometer by Brey and Kohler (1990) and the geobarometer by Kohler and Brey (1991) yields P- T estimates for Jeju-do spinel peridotites that fall in experimentally determined spinel lherzolite field in CFMASCr system (O'Neill 1981). These P-T data sets have been used to construct the Quaternary Jeju-do geotherm, which is significantly different from the conventional conductive geotherm. The xenolith-derived geotherm has a higher T gradient at low P (13 kbar) than at high P, which may be due to perturbation of the conductive heat flow by magma underplating or overplating at the crust-mantle boundary. Temperature estimates and statistics on the xenoliths indicate that the crust/mantle boundary in Jeju-do lies at about 11 kbar (~39 km). Spinellherzolite is inferred as a main constituent rock of the uppermost lithospheric mantle beneath Jeju-do. Pyroxenites were intercalated in peridotites in similar depth and temperature as re-equilibrated veins or lens.

• Current Photovoltaic Research
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• v.3 no.3
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• pp.101-105
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• 2015

ZnO is gathering great interest for large square optoelectrical devices of flat panel display (FHD) and solar cell as a transparent conductive oxide (TCO). Herewith, Mg and IIIA (Al, In) co-doped ZnO films were prepared on SLG substrate using RF magnetron sputtering system. The effect of variation of atomic weight % of Mg and ZnO have been investigated. The atomic weight % Al and In are of 3% and kept constant throughout. The numbers of samples were prepared according to their different contents, which are $M_{3%}AZO_{94%}$, $M_{4%}AZO_{93%}-(MAZO)$ and $M_{3%}IZO_{94%}$, $M_{4%}IZO_{93%}-(MIZO)$ respectively. A RF power of 225 W and working pressure of 6 m Torr was used for the deposition at $300^{\circ}C$. All of the two thin film show good uniformity in field emission scanning electron microscopy image. $M_{3%}AZO_{94%}$ thin film shows overall better performance among the all. The film shows the best lowest resistivity, carrier concentration, mobility and Sheet resistance and is found to be are of $8.16{\times}10^{-4}{\Omega}cm$, $4.372{\times}10^{20}/cm^3$, $17.5cm^2/vs$ and $8.9{\Omega}/sq$ respectively. Also $M_{3%}AZO_{94%}$ thin film shows the relatively high optical band gap energy of 3.7 eV with high transmittance more than 80% in visible region required for the better solar cell performance.

• Journal of the Korean institute of surface engineering
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• v.45 no.6
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• pp.232-241
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• 2012

Cr-Ti-B-N coatings were synthesized by a hybrid coating system combining high power impulse magnetron sputtering (HIPIMS) and DC pulse magnetron sputtering from a $TiB_2$ and a Cr target in argon-nitrogen environment, respectively. By changing the power applied on the Cr and $TiB_2$ cathodes, the Cr-Ti-B-N coatings with various Ti/Cr ratio and B content were deposited. The phase structure, microstructure and chemical compositions of the Cr-Ti-B-N coatings were studied by X-ray diffraction (XRD), transmission scanning electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). With increase of Cr element in the coatings, the nanocomposite microstructure consisting of nano-sized (Cr, Ti) N crystallites and amorphous BN phase were obtained in the coatings. The microhardness of the Cr-Ti-B-N coatings exhibited a peak value of ~41 GPa for the $CrTi_{0.1}B_{0.4}N_{1.3}$, and then decreased with further increase of Cr content in the coatings, and all the coatings exhibited low friction coefficient. The oxidation and corrosion behavior of the Cr-Ti-B-N coatings revealed better properties due to the formation of a nanocomposite microstructure.

• Economic and Environmental Geology
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• v.11 no.3
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• pp.99-108
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• 1978

The Gum-Ho river basin is one of the densely populated area having more than 35% of the total population and it was also well irrigated since earlier days in the Nackdong river basin. Most of the easily developed source of surface water are fully utilized, and at this moment the basin is at the stage that no more :surface water can be made available under the present rapid development of economic condition. Since surface water supplies from the basin have become more difficult to obtain, the ground water resources must be thoroughly investigated and utilized greatly hereafter. In economic ground of the basin what part could ground water play? In what quantities and, for what uses could it be put? The answer to these questions can be relatively simple;the ground water resources in the basin can be put at almost any desired use and almost anywhere in the basin The area of the basin is at about $2088km^2$ in the middle part of Nackdong river basin and it is located along the Seoul-Pusan express highway. The mean annual rainfall is about 974.7mm, most of which falls from June to September during the monsoon. Accumulated is appeared approximately after every 8 year's accumlated dry period with the duration of 5 years. The water bearing formation in the basin include unconsolidated alluvial deposits in Age of Quaternary, saprolite derived from weathered crystalline rocks, Gyongsang sedimentary formations of the period from late Jurassic to Cretaceouse, and igneouse rocks ranging of the Age from Mesozoic to Cenozoic. The most productive ground water reservoir in the basin is calcareous shale and sandstones of Gyongsang system, which occupies about 66% of the total area. The results of aquifer test on Gyongsang sedimentary formation show that average pumping capacity of a well drilled into the formation with drilling diameter and average depth of $8{\frac{1}{2}}$ inch and 136m is $738m^3/day$ and also average specific capacity of those well is estimated $77.8m^3/D/M$. Total amount of the ground water reserved in the basin is approximately estimated at 37 billion metric tons, being equivalent 18 years total precipitations, among which 7 billion metric tons of portable ground water can be easily utilized in depth of 200 meters.

• Korean Journal of Food Science and Technology
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• v.35 no.2
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• pp.260-265
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• 2003

Transglutaminase (TG) was prepared from Streptomyces mobaraensis to improve texture and self-life of food. In preliminary experiments, texture of the dough was not improved due to the interference in microbial TG reaction by proteases present in the crude enzyme. Among the cation exchange resins tested for the removal of proteases, MonoPlus S 100 was the most efficient. Further purification steps with a quaternary ammonia salt resin and gel permeation chromatography effectively removed proteases from crude enzyme. Molecular weight of purified enzyme was about 38,000 on SDS-polyacrylamide gel electrophoresis. Farinograph data showed the addition of purified enzyme to wheat flour gave higher stability and lower weakness values those that of crude enzyme.