• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.4
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• pp.302-313
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• 2012

Concentrations of selected heavy metals (Al, Fe, Mn, Cr, Cu, Ni, Zn, Pb, As and Cd) in surface sediments from 96 sites in Masan and Jinhae Bay were studied in order to understand metal contamination. Results show that the surface sediments were mainly enriched by Cu (18-294 ppm), Zn (67-568 ppm), Pb (10-120 ppm) and Cd (0.2-3.5 ppm). The coastal zone of Masan Bay was significantly more contaminated than the non-coastal zone, and spatial distribution pattern suggested additional sources of heavy metal input in the coastal area. The enrichment ratio and geoaccumulation index ($I_{geo}$) have been calculated and the relative contamination levels assessed in the study area. The enrichment ratios of Cu, Zn, Pb and Cd in Masan Bay have been observed to be relatively high. $I_{geo}$ results reveal that the study area is not contaminated with respect to Fe, Mn, Cr and Ni; moderately to strongly contaminated with Cu, Zn and Pb; and strongly to strong contaminated with Cd. The high contents of Cu, Zn, Pb and Cd in the study area result from anthropogenic activities in the catchment area. Based on the eight different sediment quality guideline values from USA (ERL, ERM), Canada (TEL, PEL), Australia/New Zealand (ISQG-high, ISQG-low) and Hong Kong (ISQV-low, ISQV-high), sediment quality of Masan and Jinhae Bay was also assessed and characterized.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.1
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• pp.36-44
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• 2015

The spatial and temporal distribution of dissolved trace metals has been studied to identify trends in space and time and to evaluate the pollution status in a semi-closed bay (Gohyun bay), Korea. Surface seawater samples were collected over four seasons at 18 stations in the bay between 2003 and 2004 and once at 7 stations around a large shipyard in May 2004. The concentration of Cd, Co, Cu, Ni, Pb, and Zn in seawater in February and May were highly variable in space, showing the higher value relative to other season. Those metals concentrations were decreased from inner-to outer-stations. In around the shipyard, Cu, Pb and Zn showed the higher variability depending on time. Cu and Zn concentrations at the sites around the shipyard had 2 times higher values compared with the average of inner stations in Gohyun bay. The very high correlations between salinity and either Cu and Zn has been showed. Especially, there was a significant relationship between Cu and Zn. We recognize that the shipyard is major source of Cu and Zn in seawater. Therefore, marine environment management policy such as the prevention and control of heavy metal input from a shipyard is required.

• Applied Biological Chemistry
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• v.40 no.4
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• pp.347-351
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• 1997

Contents of heavy metals in sea waters, sediments, fishes, and shellfishes from Kunsan Changhang coastal areas were investigated. Average contents of heavy metals in sea water were Pb 2.35, Cd 0.52, Cu 2.09, Zn 13.65 and $Hg\;0.24\;{\mu}g/l$. Average contents of heavy metals in sediments were Pb 19.49, Cd 0.15, Cu 9.31, Zn 20.07 mg/kg, and $Hg{\;}13.6{\;}{\mu}g/l$. Average contents of Pb, Cd, Cu, Zn, and Hg in .Acantogobius hasta were 1.08, 0.05, 2.24, 58.14, and 0.151 mg/kg and those in Mugil cephalus were 1.63, 0.05, 1.51, 32.69, and 0.065 mg/kg. Accumulation ratios of Pb and Cu in Acantogobius hasta were similar to Mugil cephalus but accumulation ratios of Zn and Hg in Acantogobius hasta were higher 2 times than in Mugil cephalus. Average contents of Pb, Cd, Cu, Zn, and Hg in Cyclina sinensis were 1.03, 1.23, 6.83, 75.83, and 0.071 mg/kg and those in Ruditapes philippinarum were 0.93, 0.86, 5.90, 52.16, and 0.074 mg/kg. Accumulation ratios of heavy metals in shellfishes were in the order of Cu>Cd>Zn>Pb>Hg, irrespective of shellfishes kind.

• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.182-186
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• 2010

Effect of cobalt substitution on the sintering behavior and magnetic properties of a NiZnCu ferrite was studied. $Ni_{0.36-x}Co_xZn_{0.44}Cu_{0.22}Fe_{1.98}O_4(0{\leq}x{\leq}0.04)$ ferrite was fabricated by a solid stat reaction method. It was proposed and experimentally verified that $Co^{2+}$ substituted NiZnCu ferrite was effective on improving the quality factor and magnetic properties of NiZnCu ferrites for multilayer chip inductors. The ferrite was sintered without sintering aids, at $880{\sim}920^{\circ}C$, for 2 h and the initial permeability, quality factor, density, shrinkage, saturation magnetization, and coercivity were also measured. The quality factor (Q) was increased linearly up to x = 0.01 and decreased rapidly over x = 0.01. As the cobalt content increased, the initial permeability and density of the ferrites decreases. The initial permeability of toroidal sample for $Ni_{0.35}Co_{0.01}Zn_{0.44}Cu_{0.22}Fe_{1.98}O_4$ ferrites sintered at $900^{\circ}C$ was 130 at 1 MHz and quality factor was 230.

• Journal of the Korean Magnetics Society
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• v.17 no.6
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• pp.232-237
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• 2007

We have synthesized the low temperature sintered of Ni-Zn-Cu ferrite with nonstoichiometric composition a little deficient in $Fe_2O_3$ from $(Ni_{0.2}Cu_{0.2}Zn_{0.6})_{1+x}(Fe_2O_3)_{1-x}$. For low loss and acceleration of grain growth $TiO_2$ and $Li_2CO_3$ was added from 0.25 mol% to 1.0 mol%. The mixture of the law materials was calcinated and milled. The compacts of toroidal type were sintered at different temperature $(875^{\circ}C,\;900^{\circ}C,\;925^{\circ}C\;950^{\circ}C)$ for 2 hours in air followed by an air cooling. Then, effects of composition and sintering temperatures on the physical properties such as density, resistivity, magnetic induction, coercive force, initial permeability, and quality factor of the Ni-Zn-Cu ferrite were investigated. The density of the Ni-Zn-Cu ferrite was $4.85\sim5.32g/cm^3$, resistivity revealed $10^8\sim10^{12}\Omega-cm$. The magnetic properties obtained from the aforementioned Ni-Zn-Cu ferrite specimens were 1,300 gauss for the maximum induction, 4.5 oersted for the coercive force, 275 for the initial permeability, and 83 for the quality factor. The physical properties indicated that the specimens could be utilized as the core of high frequency range (involved microwave range) communication and deflection yoke of T.V.

• Economic and Environmental Geology
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• v.37 no.3
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• pp.335-345
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• 2004

Total and extractable contents of heavy metals were measured in sediment and seafood from Bukhang and Boggil-ri tidal flats along the Mokpo coastal area, south-western part of Korean peninsular in order to assess the degree of metal pollution, metal bioavailability and metal hioaccumulation. The metal concentrations, except Pb were found to be greater than the background concentrations of sediments indicating the progress of cumulative contamination by anthropogenic origin of metals. The order of extractable metal concentrations in sediments were Mn(32-53 mg/kg)＞Zn(14-42 mg/tg)＞Cu(2.5-17.0 mg/kg)＞Pb(2.4-6.8 mg/kg)＞Cd(0.5-0.7 mg/kg). However, the amount of metals associated with extractable fraction of sediments were significantly high in Bukhang relative to Boggil-ri. Significant bioaccumulation of all metals, except Pb were observed in seaweed and benthos. The order of bioaccumulation of metals were: in concentration; all biota commonly, Mn(129-374 mg/kg)＞Zn(19-106 mg/kg)＞Cu(6-87 mg/kg)＞Cd(4.6-7.6 mg/kg)＞Pb(0.2-3.7 mg/kg), in BCF; Enteromorpha, Cd＞Mn＞Cu＞Zn＞Pb, Ilyoplax deschampsi, Cu＞Cd＞Mn＞Zn＞Pb, Urechis unicinctus, Cd＞Zn＞Mn＞Cu＞Pb. Some metal concentrations of Enteromorpha, especially Cu, Zn, weakly Pb in bukhang, Mn, Cd in boggili-ri, were correlate well with concentrations in sediment, indicating relatively more contaminated by the anthropogenic origin of metals in each tidal flat. The results clearly indicate that the seafood of bukhang, even of Boggili-ri known as clean area, are contaminated with metals.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.313-316
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• 2008

This work sought to examine the suitability of twin roll strip casting for Ag-27%Cu-25%Zn-3%Sn brazing alloy (BAg-7A) and to investigate the mechanical properties and microstructure of the strip. The effect of aging heat treatment on the properties was also studied,. This new manufacturing process has applications in the production of the brazing alloy. XRD and microstructural analysis of the Ag-27%Cu-25%Zn-3%Sn strip represented eutectic microstructure of a Cu-rich phase and a Ag-rich matrix regardless of heat treatment. The results of mechanical tests showed tensile strength of 470MPa, a significant enhancement, and an 18% elongation of the twin roll casted strip, due mainly to the solid solution strengthening of Zn atoms (${\sim}20%$) in the Cu-rich phases. Tensile results showed gradually decreasing strengths and increasing elongation with aging heat treatment. Microstructural evolution and fractography were also investigated and related to the mechanical properties.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.270-273
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• 2007

In this report, Indium-free and Indium-reduced thin film materials for solar absorber were studied in order to search alternative materials for thin film solar cell. The films of $Cu_2ZnSnSe_4$ and $Cu_2ZnSnSe_2$ were deposited using mixed binary chalcogenides powders. From the film bulk analysis result, it is observed that Cu concentration is a function of substrate temperature as well as CuSe mole ratio in the target. Under optimized conditions, $Cu_2ZnSnSe_4$ and $Cu_2ZnSnSe_2$ thin films grow with strong (112), (220/204) and (312/116) reflections. Films are found to exhibit a high absorption coefficient of $10^4$ $cm^{-1}$. $Cu_2ZnSnSe_4$ film shows a 1.5 eV band gap. On the other side, an increasing of optical band gap from 1.0 eV to 1.25 eV ($CuInSnSe_2$) is found to be proportional with an increasing of Zn concentration. All films have a p-type semiconductor characteristic with a carrier concentration in the order of $10^{14}$ $cm^{-3}$, a mobility about $10^1$ $cm^{2{\cdot}-1.}S^{-1}$ and a resistivity at the range of $10^2-10^6$ ${\Omega}{\cdot}m$.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.315.1-315.1
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• 2014

The use of cellulose papers has recently attracted much attention in various device applications owing to their natural advantageous properties of earth's abundance, bio-friendly, large-scale production, and flexibility. Conventional metal oxides with novel structures of nanorods, nanospindles, nanowires and nanobelts are being developed for emerging electronic and chemical sensing applications. In this work, both ZnO (n-type) nanorod arrays (NRAs) and CuO (p-type) nanospindles (NSs) were synthesized on cellulose papers and the p-n junction property was investigated using the electrode of indium tin oxide coated polyethylene terephthalate film. To synthesize ZnO and CuO nanostructures on cellulose paper, a simple and facile hydrothermal method was utilized. First, the CuO NSs were synthesized on cellulose paper by a simple soaking process, yielding the well adhered CuO NSs on cellulose paper. After that, the ZnO NRAs were grown on CuO NSs/cellulose paper via a facile hydrothermal route. The as-grown ZnO/CuO NSs on cellulose paper exhibited good crystalline and optical properties. The fabricated p-n junction device showed the I-V characteristics with a rectifying behaviour.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.7
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• pp.584-588
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• 2009

Layered ZnS/$CaF_2$/ZnS/Cu film was deposited on glass substrate by using evaporation method. ZnS and $CaF_2$ were chosen as high and low refractive materials. Cu was used as mid-reflective layer. Reflectance with different optical thickness of $CaF_2$ ranging from $0.25{\lambda}\;to\;0.5{\lambda}$ were systematically investigated by using spectrophotometer. In order to expect the experimental results, the simulation program, the Essential Macleod Program(EMP) was adopted and compared with the experimental data. Based on the results taken by spectrophotometer, the ZnS/$CaF_2$/ZnS/Cu multi-layered thin film show the maximum reflectance of 80% at 625nm $(0.25{\lambda}\;in\;CaF_2)$ and 42% at 660nm $(0.5{\lambda}\;in\;CaF_2)$ respectively. As compared with the experimental results and simulation data, it was confirmed the experimental data is well matched with the EMP data.