• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2731-2736
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• 2013

We report a new tetrameric supramolecular Cu(II) complex ($Cu_4L_4$ = tetrakis(N,N'-bis(salicylidene)-2,2'-ethylenedianiline)Copper(II)) with a Schiff-base ligand ($H_2L$ = N,N'-bis (salicylaldimine)-1,2-ethylenediamine) containing two N,O-bidentate chelate groups. Though the copper sites of $Cu_4L_4$ are non-coupled, the complex exhibits a unsually high catecholase-like activity ($k_{cat}=935h^{-1}$) when the $Cu_4L_4$ solution is treated with 3,5-di-tert-butylcatechol (3,5-DTBC) at basic condition in the presence of air. Combined information obtained from UV-VIS and EPR measurements could lead the suggestion of the reaction pathway in which the substrate may bind to Cu(II) ions by anti-anti didentate bridging mode.

• Journal of Korean Society for Quality Management
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• v.39 no.3
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• pp.422-431
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• 2011

The number of mobile telecommunication service subscribers has been over 50 millions as of the end of Nov. 2010. And the number of used mobile phones has been growing continuously caused by shortened life cycle of products and competing between service providers, which is about 21 millions for only one year, 2010 in Korea. However, the quality level of reverse logistics network for used mobile phones is very low and statistics show that the collection ratio of them has not been over 40%. The current low collection ratio can be one of the significant causes of environment destruction due to the cumulated growth. Accordingly new practical alternative recovery systems are required in addition to the current one with EPR(Extended Producers Responsibility). In this paper, suggested are alternative policies to improve the quality level of reverse logistics network for used mobile phones effectively. ENR(Extended Network service providers Responsibility) is representative of them.

• Preventive Nutrition and Food Science
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• v.14 no.1
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• pp.43-48
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• 2009

Current study investigated phytochemical compositions and antioxidant capacity of Korean leafy vegetables including chajogi, gomchwi, meowi and sseumbagwi. ${\beta}$-carotene, total soluble polyphenol, total flavonoids contents were determined, and antioxidant capacity were evaluated by various methods. ${\beta}$-carotene, total soluble polyphenol, total flavonoids contents in gomchwi were significantly higher (as much as 19 folds) compare to other vegetables (p<0.05). Sseumbagwi extract ($100{\mu}g/mL$) was removed 78.6% of superoxide radicals in xanthin-xanthin oxidase system measured by EPR. Gomchwi showed the highest nitrate scavenging activity as 94.3% at pH 1.2. In SOD-like activity, chajogi, gomchwi, and meowi were evaluated in the range of $12.6{\sim}24.5%$. All samples were revealed to prevent the reaction of ferrous chloride during 9 days, which were comparable ability with 125 mg/100 g of ${\alpha}$-tocopherol. The rich phytochemical contents of gomchwi and sseumbagwi influenced to high antioxidant capacity.

• Journal of the Korean Society for Heat Treatment
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• v.21 no.3
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• pp.150-156
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• 2008

The effects of austenitizing temperature in a range of $1000{\sim}1150^{\circ}C$ on the corrosion resistance in 420J2 stainless steel tempered at $150^{\circ}C$ were investigated by an electrochemical uniform corrosion test in a solution of 0.5M $H_2S0_4$. Pitting test and DL-EPR test for intergranular corrosion were carried out in a solution of 3.5% NaCl and 0.5M $H_2S0_4$ + 0.01 M KSCN respectively. In uniform corrosion test, specimens austenitized below $1100^{\circ}C$ showed similar corrosion current density and passive current density, whereas specimens austenitized at $1150^{\circ}C$ showed a little higher values. Pitting potential slightly increased with an increase of austenitizing temperature. The degree of sensitization, DOS, also slightly increased with an increase of austenitizing temperature, reaching the highest degree at $1150^{\circ}C$. It was expected that the increase of DOS was due to the larger grain size rather than the dissolved precipitates in the matrix.

• Macromolecular Research
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• v.15 no.4
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• pp.343-347
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• 2007

Novel composite membranes, which delivered high separation performance for propylene/propane mixtures, were developed by coating inert poly(ethylene-co-propylene) rubber (EPR) onto a porous polyester substrate, followed by the physical distribution of $AgBF_4$. Scanning electron microscopy-wavelength dispersive spectrometer (SEM-WDS) revealed that silver salts were uniformly distributed in the EPR layer. The physical dispersion of the silver salts in the inert polymer matrix, without specific interaction, was characterized by FT-IR and FT-Raman spectroscopy. The high separation performance was presumed to stem from the in-situ dissolution of crystalline silver ionic aggregates into free silver ions, which acted as an active propylene carrier within a propylene environment, leading to facilitated propylene transport through the membranes. The membranes were functional at all silver loading levels, exhibiting an unusually low threshold carrier concentration (less than 0.06 of silver weight fraction). The separation properties of these membranes, i.e. the mixed gas selectivity of propylene/propane ${\sim}55$ and mixed gas permeance ${\sim}7$ GPU, were stable for several days.

• Journal of the Korean Chemical Society
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• v.23 no.3
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• pp.152-160
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• 1979

The promoting effect of Ba or Sr addition was investigated for furfural hydrogenation reaction over copper-chromium oxide catalysts. X-ray diffraction patterns showed the appearance of $BaCrO_4$ and $SrCrO_4$ phases in Ba, and Sr promoted copper-chromium oxide catalysts. For both Ba and Sr promoted catalysts, the activity decline with reaction time was much smaller compared to that of unpromoted catalyst and copper-chromium oxide catalyst dispersed on silica, reproducible EPR signals of Cr(V) were observed when CO was adsorbed. The promoting effect of Ba addition can be interpreted in terms of active sites dispersion and stabilization.

• International journal of advanced smart convergence
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• v.9 no.1
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• pp.70-81
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• 2020

Plastics that we use and simply throw away have a life span of about 500 years and barely decompose. The practice of producing and using common plastics needs to be challenged. Until now, they have been useful in the industrial structure of mass production, but it can be said that there is a lack of research into new materials to introduce and apply in terms of material recycling. As a result of this, we have come to the uncomfortable realization of the fact that we cannot incinerate or reuse these precious resources indiscriminately. No matter how well-designed a product is, it has a competitive advantage if production and consumption activities, waste, collection, sorting and treatment are considered in terms of a continuous cycle, and in this respect, Extended Producer Responsibility (EPR) can help. We are implementing the EPR system, and active industrialization in the field of recycling is required, which is also a challenge for producers to participate actively in recycling and seek to save and recycle resources in design and manufacturing. Against this backdrop, We would like to examine the possibilities, through various studies and developments on product design of recyclable materials, which is being conducted mainly in Europe. In particular, we would like to examine the methods, and value of solving environmental problems and the active efforts to achieve this in the design world, and in particular the case of product design using recycled plastics.

• Parasites, Hosts and Diseases
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• v.49 no.2
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• pp.183-185
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• 2011

The present study was performed to determine the prevalence of Enterobius vermicularis among preschool children in Gimhae-si, Korea. A total of 6,921 preschool children in 76 kindergartens were examined using the cellotape perianal swab method. The overall egg positive rate (EPR) was 10.5%. The EPR in boys was higher than that in girls (adjusted odds ratio (AOR): 1.5, P<0.001), and it was higher in rural than in urban children (AOR: 1.2, P=0.022). The present study confirmed that the prevalence of E. vermicularis infection is fairly high among preschool children in Gimhae-si. Therefore, systematic control and preventive measures should be adopted to reduce morbidity associated with this nematode infection.

• Journal of the Korean Chemical Society
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• v.28 no.2
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• pp.109-113
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• 1984

The effects of various supports on the activity and the selectivity for the ethylene oxidation was investigated over$ Ag/{\alpha}-Al_2O_3$ and $Ag/SnO_2$ by Auger, EPR spectroscopy and reaction studies. The results indicate that over $Ag/SnO_2$ catalyst O- chemisorbed on $SnO_2 $participates in the complete oxidation of ethylene lowering the selectivity for the formation of ethylene oxide.

• Journal of the Korean Ceramic Society
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• v.34 no.6
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• pp.583-590
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• 1997

The effects of Mn2O3 and Y2O3 additives on the microstructure and dielectric properties of Sr(Zr, Ti)O3 have been investigated. Powders with Sr(Zr1-xTix)O3(0$\leq$x$\leq$0.1) composition were prepared by the conventional solid state processing from commercial TiO2 and precipitation-processed ZrO2. The powders containing sintering additives of Mn2O3 and Y2O3 were compacted and then sintered at 1,55$0^{\circ}C$ for 4 h to get>97% relative density. Mn2O3 suppressed the grain growth and Y2O3 enhanced the density of sintered body. The oxidation state of Mn ions were determined by a chemical wet method and EPR spectroscopy. Mn ions were present as Mn2+ and Mn4+ in SrZrO3, while as Mn3+ and Mn4+ in Ti-substituted Sr(Zr, Ti)O3. With the substitution of Ti, the lattice parameters of SrZrO3 decreased and its dielectric constant increased with remarkable decrease in Q value. The dielectric constant of Sr(Zr, Ti)O3 was in the range of 30 to 40, Q values 1,200~5,400 at 6 GHz and temperature coefficient of resonant frequency -67~100 ppm/K.