• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.639-644
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• 2011

A simple and highly sensitive chemiluminescence method to determine norfloxacin (NFLX) has been proposed by measuring the chemiluminescence (CL) intensities using a flow injection (FI) system. The CL intensity of the luminol-$H_2O_2$ system is strongly enhanced by the addition of Cu (II) in alkaline condition. The CL intensity is substantially increased after the injection of NFLX into the luminol-$H_2O_2$-Cu (II) system. The enhancement effect is attributed to a catalytic effect of Cu (II) due to the interaction with NFLX which forms a complex with the catalyst. Under the optimal conditions, the sensitizing effect of the CL intensity is proportional to the concentration of NFLX in the range of $1.5{\times}10^{-9}-5.9{\times}10^{-7}molL^{-1}$ (r = 0.9994) with a detection limit ($3{\sigma}$) of $2.98{\times}10^{-10}molL^{-1}$. The proposed method had good reproducibility with the relative standard deviation (RSD, n = 5) of 1.6% for $1{\times}10^{-7}molL^{-1}$ of NFLX. The possible reaction mechanism of the CL reaction is also discussed. This method has been successfully applied for the determination of trace amount of NFLX in pharmaceutical preparations and serum samples.

• Journal of Korea Soil Environment Society
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• v.2 no.3
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• pp.31-38
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• 1997

Temporal and spatial comparisons of acid mine drainage contaminated waters are difficult because of the complex physico-chemical nature of the pollutant. In the present study, an acid mine drainage index has been developed and evaluated for the assessment of surface waters. AMD index is calculated using a modified arithmetic weighted index using seven parameters which are most indicative of AMD contamination, i. e. pH value, sulphate, iron, zinc, aluminum, copper and manganese. Weighting is used to express the relative indicator value of each parameter. The proposed AMD index is used to quantify contamination from acid mine drainage over ten different old mine sites and assess the degree of impact on surface on surface waters. As a result of AMD evaluation, the Sukbong Mine located near the Moonkyung province showed lowest AMD value indicating the worst acid mine drainage quality. In overall, Youngdong mine sites showed higher contaimination compared to the other mine sites including Youngsuh, Choongbu, Suhbu and Nambu area.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1833-1836
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• 2008

Recently as the micro surface features become higher and diverse in their shapes, the releasing of the molded features becomes more crucial for manufacturing of the micro patterned products. The higher aspect ratio of the features or more complex shape of the features results in larger releasing force, elongation or cohesive failure of the features during the releasing. Another issue would be the uniformity of the released surface features after molding, especially for applications with large area surface. The micro patterned optical film, one of typical applications for micro surface features, consists of two layers, the thermoplastic base film and the micro formed UV resin layer. Therefore two interfaces are typically involved during the forming of this micro featured film; one is between the base film and the UV resin and another is between the resin and the pattern master. To improve the releasing of the molded surface features, the adhesive characteristic was investigated at these two interfaces. A PET film was used as a base film and two UV curable resins with different surface energy were prepared for different adhesiveness. Also the two different pattern masters were employed; one is made from brass-copper alloy and fabricated with PMMA. The adhesiveness at each interface was measured for some combinations of these base film, UV resins and the masters and the effect of this adhesiveness on the releasing was investigated.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.2
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• pp.137-145
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• 2000

Carcinogenesis is a multi-stage process that generally consists of at least three steps; initiation, promotion, and progression. If one of these carcinogenic steps were suppressed or delayed, the cancer could be prevented. Cancer chemoprevention is defined to be inhibition or reversal of the carcinogenic process by the specific chemical agents and is a novel approach to cancer management alternative to conventional chemotherapy. Chlorophylln(CHL), a water-soluble derivative of chlorophyll, containing sodium and copper, has been known to be strong antimutagen in several test systems, but its mechanism of antimutagenic action is unknown. In the present experiment, the possibility of CHL as chemopreventive drugs on 7,12-dimethylbenz[a]anthracene(DMBA)-induced hamster buccal pouch carcinogenesis was investigated by mutagenicity test, carcinogenicity test, and frequency or spectrum of H-ras mutations in the both of DMBA-induced and chlorophylln-pretreated-DMBA induced tumor by polymerase chain reaction and non-isotopic restriction fragment length polymorphism. The treatment of CHL reduced the yields and multiplicity of the 0.5% DMBA-induced tumor, 86% to 62.5% and $3.7{\pm}0.6$ to $1.4{\pm}0.3$, respectively. The occurrence of histidine revertant by $20{\mu}mole$ DMBA was inhibited 25.6 to 81.7% by 1 to $5{\mu}M$ CHL in a dose-dependent manner. The mutation rates of H-ras gene in DMBA-induced and CHL-pretreated-DMBA induced tumor were 96%, 94% of which the most mutations were in codon 12/13. These results suggest that CHL inhibits the carcinogenic action of DMBA by the formation of complex between CHL and DMBA or the inhibition of the activation of DMBA in vivo. But CHL did not affect the mutation rates or its spectrum in already formed tumor.

• Economic and Environmental Geology
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• v.29 no.1
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• pp.87-103
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• 1996

The purposes of this research are to investigate the pollution level of heavy metals due to the urbanization and industrialization in the satellite cities of Seoul, and to assess the chemical species and the sources of heavy metals in highly contaminated soils and dusts. Soil and dust samples were collected from the Uijeongbu and the Koyang cities, which are northern and the northwestern satellite cities of Seoul metropolitan city, respectively. Relatively high pH values($6.3{\sim}9.9$) were found in roadside soils compared with agricultural and forest soils. Difference in pH values of soils was not identified between before and after rainy seasons. In spite of no specific pollution sources in the above cities, the contents of Cu, Pb, and Zn in soils and dusts were much higher than the world average contents. The metal levels in dusts were higher than those in soils, but the metal concentration in dusts was significantly decreased after rainy season. Pollution index was high(> 1.0) in the areas of heavy traffic, industrial complex, and city centres. There is an appreciable proportion of total Zn in exchangeable/water-acid soluble fraction. Copper is predominantly associated with reducible and oxidizable phases, whereas Pb is largely in reducible association. It is concluded that the mobility and bioavailability of metals are high in the order of Zn >> Cu > Pb, on the basis of characteristic particle morphology and chemical composition, Pb-containing particles are originated probably from the automobile exhaust, particularly in heavy traffic areas. The metallic forms and iron-oxide associated forms of Cr, Ni, Cu, Zn, and Pb can be assessed as industrial origin.

• Journal of the Korean Society of Visualization
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• v.7 no.2
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• pp.17-21
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• 2010

This paper presents the fabrication and performance measurement of a temperature sensor array on a flexible substrate attachable to a curved surface using MEMS technology. Specifically, the fabrication uses the well-developed printed circuit board fabrication technology for complex electrode definition. The temperature sensor array are lifted off with a $10{\times}10$ matrix in a $50\;mm{\times}50\;mm$ to visualize temperature distribution. Copper is used as temperature sensing material to measure the change in resistances with temperature increase. In a thermal oven with temperature control, the temperature sensor array is Characterized. The constant slope of resistance change is obtained and temperature distribution is measured from the relationship between resistance and temperature.

• Journal of Wetlands Research
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• v.12 no.3
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• pp.15-20
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• 2010

The contamination loadings generated in Changwon City are coming into Masan Bay through the Bongam tidal flat except the loadings collected and transferred by sewer lines to the wastewater treatment plant. The recovery of waterbirds, shellfishes, and fishes has been quite well recognized in recent years after the first implementation of Masan Bay TPLM (Total Pollution Loads Management) in Korea. This tidal flat has been conserved by the cooperation of several stakeholders and utilized as an ecosystem field site for in situ education. A large industrial complex has been operated since 1970's, therefore increasing the level of pollutants in estuary and costal sediments, especially by heavy metals. Zinc, copper, and lesd contamination of sediment was revealed at higher level by Clean-up guideline (MOMAF) or heavily polluted level by SQC (USEPA). There was a significant difference between two sites at the 95% confidence level, which implies no homogeneity in the processes of transport and deposition even at 500 m of distance. The heavy metal concentrations in the Bongam sediments have been gradually decreased with comparing the data of 2006, and 2009.

• Korean Journal of Materials Research
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• v.30 no.9
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• pp.453-457
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• 2020

Tomb No. 1 (Donghachong) of the Buyeo Neungsan-ri Tomb complex (listed as UNESCO World Heritage Site), is a royal tomb of the Baekje Sabi Period. One wooden coffin unearthed there is an important relic of the funerary culture of the Baekje. This study examines the production techniques of gilt-bronze objects attached to the wooden coffin excavated from Donghachong. The base metal of the gilt-bronze object is pure copper, with single α phase crystals in a heterogeneous form containing annealing twins; Au and Hg are detected in the gilt layer. We suggest that the surface of the forging copperplate is gilded using a mercury amalgam technique; it is thought that the annealing twins of the base material formed during the heat treatment process for the sheet metal. The gilt layer is three to five times thicker for the gilt-bronze objects found near the foot of the coffin than those near the head. We estimate the plating process is carried out at least three times because three layers are identified on the plate near the head. Therefore, it is likely that the materials and methods used to construct the gilt-bronze objects found in different parts of the coffin are the same, but the number of platings is different. This research confirms the metal crafting techniques used in Baekje by the examination of production techniques of these gilt-bronze objects. Further, our paper presents an important example of restoration and reconstruction for a museum exhibition, through effective use of scientific analysis and investigation.

• Bulletin of the Korean Chemical Society
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• v.24 no.3
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• pp.350-356
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• 2003

The mechanism of the decomposition of a bronchodilator, S-nitroso-N-acetyl-D,L-penicillamine (SNAP) by a bronchoconstrictor, aqueous sulfite, has been investigated in detail. The decomposition was studied using a conventional spectrophotometer at 336 nm over the ranges: 0.010 ≤ $[S^{IV}]_T$ ≤ 0.045 mol $dm^{-3}$, 3.96 ≤ pH ≤ 6.80 and 15.0 ≤ θ≤ 30.0 ℃, 0.60 ≤ I ≤ 1.00 mol $dm^{-3}$, and at ionic strength 1.00 mol $dm^{-3}$ (NaCl). The rate of reaction is dependent on the total sulfite concentration and pH in a complex manner, i.e., $k_{obs}\;=\;k_1K_2[S^{IV}]_T/ ([H^+]\;+\;K_2)$. At 25.0 ℃, the second order rate constant, $k_1$, was determined as $12.5\;{\pm}\;0.15\;mol^{-1}\;dm^3\;s^{-1}$. ${\Delta}H^{neq}\;=\;+32\;{\pm}\;3 kJ\;mol^{-1}\;and\;{\Delta}S^{\neq}\;=\;-138\;{\pm}\;13\;J\;mol^{-1}K^{-1}$. The N-nitrosohydroxylamine-N-sulfonate ion was detected as an intermediate before the formation of any of the by-products, namely, N-acetyl-D,L-penicillamine. The effect of concentration of aqueous copper(Ⅱ) ions on this reaction was also examined at pH 4.75, but there was no dependence on $[Cu^{2+}]$. In addition, the $pK_a$ of SNAP was determined as 3.51 ± 0.06 at 25.4 ℃ [I = 1.0 mol $dm^{-3}$ (NaCl)].

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1757-1762
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• 2006

A solvent sublation using salphen as a ligand was studied and applied for the determination of trace Ni(II), Co(II) and Cu(II) in water samples. The fundamental study was investigated by a solvent extraction process because the solvent sublation was done by extracting the floated analytes into an organic solvent from the aqueous solution. The salphen complexes of Ni(II), Co(II) and Cu(II) ions were formed in an alkaline solution of more than pH 8 and then they were extracted into m-xylene. It was known that the each metallic ion formed 1 : 1 complex with the salphen and the logarithmic values of extraction constants for the complexes were 3.3 5.1 as an average value. Based on the preliminary study, the procedure was fixed for the separation and concentration of the analytes in samples. Various conditions such as the pH of solutions, the influence of $NaClO_4$, the bubbling rate and time of $N_2$ gas, and the type of organic solvent were optimized. The metal-salphen complexes could be extracted into m-xylene from the solution of more than pH 8, but the pH could be shifted to acidic solution of pH 6 by the addition of $NaClO_4$. In addition, the solvent sublation efficiency of the analytes was increased by adding $NaClO_4$. The recovery of 97-115% was obtained in the spiked samples in which given amounts of 0.3 mg/L Ni(II), 0.8 mg/L Co(II) and 0.04 mg/L Cu(II) were added.