• Analytical Science and Technology
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• v.13 no.6
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• pp.810-814
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• 2000

The open-chain hexadentate $N_4$, $O_2$ ligands 1, 15-bis(2-hydroxybenzyl)-2, 6, 10, 14-tetraazapentadecane (BSATPD. 4HCl) has been synthesized as its tetrahydro-chloride salt and characterized by EA, IR, NMR, and Mass spectrum. Its protonation constants ($logK_n{^H}$) and stability constants ($logK_{ML}$) for $Cu^{2+}$, $Ni^{2+}$, $Co^{2+}$ and $Zn^{2+}$ ions were determined in aqueous solution by potentiometry and compared with those of analogous $N_4$, $O_2$ ligands contain ethtylenic spacers or propylenic spacers, which make six-membered chelate rings between the aliphatic nitrogen atoms.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.45-46
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• 2015

Se 원소가 포함된 $CuIn_xGa_{1-x}Se_2$(CIGS) 단일 스퍼터링 타겟을 이용하여 후처리 공정없이 단일 스퍼터링 공정만으로 CIGS 흡수층 박막을 증착하여 소자 특성을 확인하였다. 단일 CIGS 흡수층 공정이 적용된 CIGS 박막태양전지 소자(유리기판/Mo/단일 CIGS 흡수층 박막/CdS/i-ZnO/Al-doped ZnO/Ni-Al grid)에서 10.0%의 태양광 변환 효을을 달성하였으며, 이는 기존의 복잡한 공정구조를 해결하여 대면적 양산화 CIGS 제조 공정에도 적용할 수 있음을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.274-275
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• 2005

The tensile strain dependency of critical current in YBCO coated conductors was examined at 77K and in the self magnetic field. A commercially available YBCO sample with Cu stabilizer layer was supplied. There existed a peak in the relation between the Ie and tensile strain, and the reversible variation of $I_c$ with applied tensile strain was found. In the neutral axis Ni alloy RABiTS-$Y_2O_3$/YSZ/$CeO_2$ buffered YBCO tape, the $I_c$ recovered reversibly until the applied strain reached to about 0.5%, representing that a significant residual compressive strain induced during cooling to 77 K influenced the axial strain tolerance of YBCO conductors. To investigate the strain and stress influence on the $I_c$, the stress-strain characteristics of YBCO conductors measured at 77 K were discussed.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.158-164
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• 1996

This survey was conducted to investigate the distribution of heavy metal contents in medicinal plants and soils. Plant and soil samples were collected at 254 sites(Angelica gigas : 81, Astragalus membranceus : 38, Platycodn glandiflorum : 36, Paeonia albilora : 34, Codonopsis lanoceolata : 32, Ligusticum chuanxiong : 17, Bupleurum falcatum : 16, respectively) over the country, Soil texture, pH values and heavy metal content of soils and medicinal plants were evaluated as major factors. Soil texture classification showed that sandy loam, loam, loamy sand and silt loam were 46.1%, 26.0%, 19.3% and 8.6% of the total, respectively. The contents of O.M, Ex.Ca. Ex.Mg and EC value were higher in loamy(sandy loam, loam and silt loam)soils than in sandy(loamy sand)soils, but available $P_2O_5$ contents of loamy sand soils were higher than those of sandy loam, loam, and silt loam. The contents of Cd, Cu, Pb, Zn and Ni in soil were high in loamy soils, while Cr content was high in loamy silt soils. The contents of Cu and Cr in Angelica gigas were high in loamy soils, and those of Pb in Astragalus membranceus, Paeonia albiflora and Codonopsis lanoceolata were high in sandy loam soils. Correlation coefficients between heavy metal contents in medicinal plants and their soils with soil texture were positively correlated in sandy loam and loam at Cu, loam at Zn, sandy loam, loam and loamy sand at Cr, respectively. Correlation coefficients between pH value of the soils and contents of Cd, Zn and Ni in medicinal plants were negatively correlated, but those of Cd, Pb, Zn and Ni in soils were positively correlated.

• Corrosion Science and Technology
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• v.7 no.2
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• pp.119-124
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• 2008

Steel is generally not corrosion resistant to water with formation of non protective rusts on its surface. Rusts are composed of iron oxides such as $Fe_3O_4$, $\alpha-$, $\beta-$, $\gamma-$and ${\delta}-FeOOH$. However, steel, particularly weathering steel containing small amounts of Cu, Ni and Cr etc., shows good corrosion resistance against rural, industrial or marine environment. Its corrosion rate is exceedingly small as compared with that of carbon steel. According to the exposure test results undertaken in outdoor environments, the atmospheric corrosion rate for weathering steel is only 1 mm for a century. Atmospheric corrosion for steels proceeds under alternate dry and wet conditions. Dry condition is encountered on steel surface on fine or cloudy days, and wet condition is on rainy or snowy days. The reason why weathering steel shows superior atmospheric corrosion resistance is due to formation of corrosion protective rusts on its surface under very thin water layer. The protective rusts are usually composed of two layer rusts; the upper layer is ${\gamma}-FeOOH$ termed as lepidocrocite, and inner layer is nano-particle ${\alpha}-FeOOH$ termed as goethite. This paper is aimed at elucidating the atmospheric corrosion mechanism for steel in comparison with corrosion in bulky water environment by use of empirical data.The summary is as follows: 1. No corrosion protective rusts are formed on steel in bulky water. 2. Atmospheric corrosion for steel is the corrosion under wetting and drying conditions. Corrosion and passivation occur alternately on steel surface. Steel, particularly weathering steel with small amounts of alloying elements such as Cu, Ni and Cr etc. enhances forming corrosion protective rusts by passivation.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.10
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• pp.4761-4767
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• 2016

Objective: The use of Shamma (smokeless tobacco) by certain groups is giving rise to health problems, including cancer, in parts of Saudi Arabia. Our objective was to determine metals levels in Shamma using inductively coupled plasma mass spectrometry (ICP-MS). Methods: Thirty-three samples of Shamma (smokeless tobacco) were collected, comprising four types: brown Shamma (n = 14.0), red Shamma (n = 9.0), white Shamma (n = 4.0), and yellow Shamma (n = 6.0). All samples were collected randomly from Shamma users in the city of Najran. Levels of 11 elements (Al, As, Cd, Co, Cr, Cu, Li, Mn, Ni, Pb, and Zn) were determined by ICP-MS. Results: A mixed standard (20 ppb) of all elements was used for quality control, and average recoveries ranged from 74.7% to 112.2%. The highest average concentrations were found in the following order: Al ($598.8-812.2{\mu}g/g$), Mn ($51.0-80.6{\mu}g/g$), and Ni ($23.2-53.3{\mu}g/g$) in all four Shamma types. The lowest concentrations were for As ($0.7-1.0{\mu}g/g$) and Cd ($0.0-0.06{\mu}g/g$). Conclusions: The colour of each Shamma type reflects additives mixed into the tobacco. Cr and Cu were showed significant differences (P < 0.05) among Shamma types. Moreover, Pb levels are higher in red and yellow Shamma, which could be due to use (PbCrO4) as yellow colouring agent and lead tetroxide, Pb3O4 as a red colouring agent. The findings from this study can be used to raise public awareness about the safety and health effects of Shamma, which is clearly a source of oral exposure to metals.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.16.2-16.2
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• 2011

Graphene has attracted significant attention due to its unique characteristics and promising nanoelectronic device applications. For practical device applications, it is essential to synthesize high-quality and large-area graphene films. Graphene has been synthesized by eloborated mechanical exfoliation of highly oriented pyrolytic graphite, chemical reduction of exfoliated grahene oxide, thermal decomposition of silicon carbide, and chemical vapor deposition (CVD) on metal substrates such as Ni, Cu, Ru etc. The CVD has advantages over some of other methods in terms of mass production on large-areas substrates and it can be easily separated from the metal substrate and transferred to other desired substrates. Especially, plasma-enhanced CVD (PECVD) can be very efficient to synthesize high-quality graphene. Little information is available on the synthesis of graphene by PECVD even though PECVD has been demonstrated to be successful in synthesizing various carbon nanostructures such as carbon nanotubes and nanosheets. In this study, we synthesized graphene on $Ni/SiO_2/Si$ and Cu plate substrates with CH4 diluted in $Ar/H_2$ (10%) by using an inductively-coupled PECVD (ICPCVD). High-quality graphene was synthesized at as low as $700^{\circ}C$ with 600 W of plasma power while graphene layer was not formed without plasma. The growth rate of graphene was so fast that graphene films fully covered on substrate surface just for few seconds $CH_4$ gas supply. The transferred graphene films on glass substrates has a transmittance at 550 nm is higher 94%, indicating 1~3 monolayers of graphene were formed. FETs based on the grapheme films transferred to $Si/SiO_2$ substrates revealed a p-type. We will further discuss the synthesis of graphene and doped graphene by ICPVCD and their characteristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.1
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• pp.17-22
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• 2017

Effects of pH value and deposition time on the electrical properties of (NMC) Ni-Mn-Cu-O and (NMCC) Ni-Mn-Cu-Co-O thin films were investigated. The NMC and NMCC films were prepared by spin spray method. The crystal structure and thickness of the annealed films were changed by the pH value and deposition time, respectively. A single phase of cubic spinel structure was confirmed for the annealed films deposited from solutions with pH 7.6. The resistivity of the annealed films was affected by the crystal structure and microstructure. The TCR (temperature coefficient of resistance) was dependent on the $Mn^{3+}/Mn^{4+}$. Typically, the resistivity of $70.5{\Omega}{\cdot}cm$ and TCR of -3.56%/K at room temperature were obtained for NMCC films deposited from solutions with pH 7.6 for 5 min, and annealed at $450^{\circ}C$ for 3 h.

• Korean Journal of Microbiology
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• v.23 no.3
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• pp.177-183
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• 1985

Some properties of an extracellular cytosine deaminase produced from Arthrobacter sp.JH-13 were examined after 20-80% of ammonium sulfate fractionation. Among some substrates, this enzyme utilized cytosine and 5-fluorocytosine as a substrate. The optimum pH and temperature for the activity of this enzyme were found to be near 8.0 and $40^{\circ}C$, respectively. The ensyme was more stable in 0.2M of Tris-HCl buffer than 0.2M of potassium phosphate buffer. The enzyme was generally stable below $50^{\circ}C$, but inactivated completely at $70^{\circ}C$. 1mM of $Fe^{3+},\;K^+\;and\;Na^+$ increased the enzyme activity, but 0.01mM of $Co^{2+},\;Cu^{2+},\;Ni^{2+},\;Hg^{2+},\;Ag^{2+},\;Zn^{2+},\;Ba^{2+},\;and\;Mg^{2+}$ markedly inactivated the enzyme activity. 0.1mM of p-chloromercuribenzoate, trichloroacetic acid, and N-ethylmaleimide compleyely inhibited the enzyme activity, but 0.1mM of 2-mercaptoethanol slightly increased the enzyme activity.

• Korean Journal of Materials Research
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• v.10 no.8
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• pp.569-574
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• 2000

To improve the ductility of $Al_3Hf$ and $Al_3Ta$ intermetallic compounds, which are the potential temperature structural materials, the mechanical alloying behaviour and the effect of ternary additions on the $Ll_2$ phase formation were investigated. During the mechanical alloying by the SPEX mill, the $Ll_2$ $Al_3Hf$ intermetallic compound was formed after 6 hours of milling in AL-25%Hf system. In AL-25%Ta system, however, only the $D0_{22}$ $Al_3Ta$ intermetallic compound was formed until 30 hours of milling and the $Ll_2$ phase was not observed. In AL-12.5%M-25%Ta(M=Cu, Zn, Mn, Fe, Ni) systems, the additions of Cu and Zn had no effect on the $D0_{22}$ structure of the binary $Al_3Hf$ and the additions of Mn, Fe and Ni produced the amorphous phase. Therefore it was considered that these ternary additions could not overcome the energy difference between $Ll_2$ and $D0_{22}$ structures in the $Al_3Hf$ intermetallic compound. In AL-12.5%M-25%Hf(M=Cu, Zn, Mn, Fe, Ni)systems, the additions of Cu and Zn did not affect the $Ll_2$ structure of the binary $Al_3Hf$ but the additions of oMn, Fe and Ni produced the amorphous phase as they did in AL-12.5%M-25%Ta systems. Therefore, it was considered that the Ni, Mn and Fe additions promote the formation of amorphous phase in $Al_3X$ intermetallic compounds.