• Journal of Environmental Health Sciences
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• v.29 no.3
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• pp.21-27
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• 2003

The purpose of this study was to investigate the distribution and characteristics of heavy metals in the fallout dust deposits at the middle and high schools. We collected the samples at 60 schools in Kongju, Incheon and Daejeon on from September to November, 2001, and analyzed Cadmium(Cd), Copper(Cu), Lead(Pb) and Zinc(Zn) from them. Zn was the highest level as 551 $\pm$ 79.9 ppm, and the next order were Pb, Cu, and Cd as 146.0 $\pm$ 15.2 ppm, 98.7 $\pm$ 14.4 ppm and 5.21 $\pm$ 0.76 ppm, respectively. The rates of schools exceeding the soil environmental standards were 56.3% in Cd, 53.3% in Zn, 51.5% in Pb, and 31.7% in Cu, respectively. Cd and Pb were the highest levels at schools in Daejeon as 6.30 $\pm$ 0.87 ppm and 171 $\pm$ 26.1 ppm, respectively. Cu and Zn were the highest levels at schools in Incheon as 176.2 $\pm$ 55.8 ppm and 919.8 $\pm$ 185.7 ppm, respectively. At Incheon, Cu and Zn levels were significantly higher than Kongju(p=0.04l), and Daejeon(p=0.016), respectively. Total pollution index(PI) of heavy metals was 1.51 $\pm$ 0.16. PI was 2.00 $\pm$ 0.51 on Incheon, 1.50 $\pm$ 0.13 on Daejeon, and 0.92 $\pm$ 0.24 on Kongju. Correlations were 0.675 (p<0.05) between Cu and Cd, 0.663(p<0.05) between Cu and Zn, and 0.477 between Cd and Pb. In conclusion, Among heavy metals in the fallout dust deposits at schools, Cu and Zn were the highest levels at Incheon, Cd and Pb were the highest levels at Daejeon.

• Journal of Nutrition and Health
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• v.24 no.4
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• pp.326-336
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• 1991

Present study was to investigate the effect of dietary vegetable sources such as carrot, peahull and squash on mineral balance of Na, K, Ca, Fe, Cu, Zn and Mg in mice. It would also determine if the kind, level and feeding period of vegetables can affect the mineral balance. One hundred and thirty mice weighing $29{\sim}30g$(8 weeks of age) were randomly selected. Ten mice were fed their standard diet, and the others were divided into three experimental groups that were fed standard diet supplemented with carrot, peahull and squash. Mineral intake and urinary and fecal excretion of minerals were measured to investigate the effect of the kind, level and feeding period of vegetables on absorption rate and balance of minerals. Body-weight gain was increased in high peahull diet group compared to the control. No significant difference was observed for feed efficiency ratios between different experimental groups and urine volume was increased by vegetable fed group. Na, Ca, Fe, and Cu intake were lower in high squash-diet fed soup. K intake was higher in carrot fed mice, and Zn, and Mg intake were higher in peahull fed mice. Absorption rate and balance of mineral in control group resulted in positive balance while experimental groups showed negative. The kind of vegetable, feeding level and feeding period affected the intake of Na, K, Ca, Cu and absorption rate of Cu, Zn and balance of K, Cu, Zn to negative. In spite of the higher intake of t Zn and Mg, in experimental groups the absorption rate showed negative balance.

• 한국해양학회지
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• v.18 no.1
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• pp.29-42
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• 1983

This stidy was intended to investigate the heavy metal contents in the bottom sediments of the continental shelt around the Jeju Island and ot the southern coastal area of the Korean Peninsula. For this study 39 bottom sedinent samples were taken from the study area using Phleger gramity corer and Snapper. The average contents of heavy metals were 59.1 ppm Zn, 362.6 ppm Mn, 63.8 ppm Cr, 15.7 ppm Pb, 10.0 ppm Co, 28.9 ppm Ni, 10.5 ppm Cu, and 2.7% Fe in the surficial sediments around the Jejr Island; and 79.ppm Zn, 384 ppm Mn, 8.6 ppm Pb, 17.8 ppm Ni, 23.2 ppm Cu, and 1.59 % fe in those of nearsgore of the southern coastal area respectively. The heavy metal contents were higher in the northwestern part around the Jeju Island compared to those in other region. However, these tendencies were not the result of pollution, but of the differences of grain size of the sedimenrs. In the nearshore of the southern coast, the heavy metal contents did not show any geographical tendency. However, those of Masan and Jinhae Bays wew higher than those of the other region. These seemed to be caused by waste disposal from the industrial compsex located at the adjacent land. Nevertheless these values of heavy metal content except for Zn and Cu in Masan Bay and inner bay of Jinhae are lower than the average values of the each world-wide data of the nearshore sedimentl. The pair correlations of the cach heavy metal elements were calculated by regressino analysis using VAX 780 computer. the following pair elements, such as Zn-Cu, Ni-Cu, Fe-cu, Cr-Cu, Co-Zn, Ni-Zn, Cr-Zn, Ni-Co, Fe-Co, Cr-Co, Fe-Ni, Cr-Ni and Cr-Fe show closely posetive linear correlations in the sediments around the Jeju Island. In general, the heavy metal content increases in proportion to the increase of the mean values of the grain size of the sediments around the Jeju Island. In the southern coastal area, in gineral, thepair correlations of each heavy metal elements did not southern coastal area, in general, the pair correlatttttions of rach heavy metal elements did not show any positive correlation except for the positive linear correlations of Cu-Zn, Cu-ni and Ni-Mn. It is interpreted as a result of the differences of the physecochemical environment of the sampling sites and also of the influences of the ondustrial wastes from the manufacturing factores located at the coastal zone of the study area.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.74.2-74.2
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• 2000

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.389-402
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• 1999

Single crystal of Li2Cu1-xMxO4 (M=Ni, Zn) are promising as a substrate to realize superconducting electronic devices. The distribution coefficients of Ni and Zn to the Cu site in La2CuO4 (LCO) were estimated by the zone melting technique to grow high quality single crystals of La2Cu1-xMxO4(M=Ni, Zn). The distribution coefficient value of Ni was estimated to be 4.2 and that of Zn was estimated to be 0.66, respectively. Suitable solvent compositions were determined using these values to grow single crystals by he traveling floating zone (TSFZ) method. Single crystal of LCO, La2Cu1-xMxO4(M=Ni(x=0.01, 0.02, 0.03, 0.04), Zn(x=0.01, 0.02, 0.03) of high homogeneity were grown. The behaviors of the magnetization of these as-grown crystals do not indicate superconductivity except LCO. Ni or Zn substitution can make LCO non superconductor. This fact suggest that single crystals substituted by Ni or Zn are useful as substrate crystals.

• Journal of Korea Foundry Society
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• v.29 no.6
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• pp.265-269
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• 2009

The optimum RRA heat treating conditions and SCC (stress corrosion cracking) resistance of semi-solid Al-Zn-Mg-Cu alloy fabricated by inclined cooling plate were compared with those of conventional mould cast alloys. The non-stirring method characterized by using a cooling plate can effectively eliminate dendritic structure and form a fine globular semisolid microstructure in as-cast Al-Zn-Mg-Cu alloy and the SCC resistance of semi-solid Al-Zn-Mg-Cu alloy was higher than that of conventional mold cast alloy. Also, after retrogressed treatment at RRA heat treatment of semi-solid Al-Zn-Mg-Cu alloy, retrogressed treatment time has increased more than 10 minutes at $180^{\circ}C$ to recovery the T6 heat treatment strength.

• Transactions on Electrical and Electronic Materials
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• v.13 no.6
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• pp.305-309
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• 2012

In this study, ZnO nanorods and $SnO_2$-CuO heterogeneous oxide were grown on membrane-type gas sensor platforms and the sensing characteristics for carbon monoxide (CO) were studied. Diaphragm-type gas sensor platforms with built-in Pt micro-heaters were made using a conventional bulk micromachining method. ZnO nanorods were grown from ZnO seed layers using the hydrothermal method, and the average diameter and length of the nanorods were adjusted by changing the concentration of the precursor. Thereafter, $SnO_2$-CuO heterogeneous oxide thin films were grown from evaporated Sn and Cu thin films. The average diameters of the ZnO nanorods obtained by changing the concentration of the precursor were between 30 and 200 nm and the ZnO nanorods showed a sensitivity value of 21% at a working temperature of $350^{\circ}C$ and a carbon monoxide concentration of 100 ppm. The $SnO_2$-CuO heterogeneous oxide thin films showed a sensitivity value of 18% at a working temperature of $200^{\circ}C$ and a carbon monoxide concentration of 100 ppm.

• Journal of Surface Science and Engineering
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• v.41 no.3
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• pp.109-113
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• 2008

High strength 7xxx series Al-Zn-Mg alloy have been investigated for using light weight automotive parts especially for bump back beam. The composition of commercial 7xxx aluminum has the Zn/Mg ratio about 3 and Cu over 2 wt%, but this composition isn't adequate for appling to automotive bump back beam due to its high resistance to extrusion and bad weldability. In this study the Zn/Mg ratio was increased for better extrusion and Cu content was reduced for better welding. With this new composition we investigated the effect of composition on the resistivity against stress corrosion cracking. As the Zn/Mg ratio is increased fracture energy obtained by slow strain rate test was decreased, which means degradation of SCC resistance. While the fracture energy was increased with Cu contents although it is below 1%, which means improvement of SCC resistance. These effects of composition change on the SCC resistivity were identified by observing the fracture surface and crack propagation.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.94-94
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• 2003

• Solar Energy
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• v.17 no.3
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• pp.51-57
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• 1997

Cu-doped ZnTe thin films have been grown by hot-wall evaporation. The electrical conductivity of the intrinsic ZnTe film was of p-type and as low as $10^{-6}({\Omega}{\cdot}cm)^{-1}$. As the doped Cu concentration was increased, the electrical conductivity was increased. up to $10^2({\Omega}{\cdot}cm)^{-1}$, but the mobility was decreased a little. The heavily doped sample shows the metal-like electrical resistivity.