• Journal of the Korean Vacuum Society
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• v.22 no.3
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• pp.156-161
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• 2013

We fabricated transparent conductive electrodes with silver (Ag) nanofibers by electrospinning process. Ag nanofibers have high aspect ratio and fused junctions which result in low sheet resistance. Electrospinning is a fast and efficient process to fabricate continuous one-dimensional (1D) nanofibers. Ag/polymer ink were prepared in polymer matrix solution by a sol-gel method. Then, Ag/polymer nanofibers precursors are heated at $200{\sim}500^{\circ}C$ in air for 2 h to eliminate partially the polymers. The topographical features of the Ag nanofibers were characterized by FE-SEM, and the electrical property was analyzed through I-V measurement system. Finally, optical property was measured using UV/VIS spectroscopy. The transparent conductive electrodes with Ag nanofibers exhibited a sheet resistance (Rs) of $250{\Omega}/sq$ at a transparency (T) of 83%. Transparent conductive films, contain the Ag nanofibers as conductive materials, have good electrical, optical, and mechanical properties. Therefore, it is expected to be useful for the application of flexible display in the future.

• Journal of the Korean Magnetics Society
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• v.17 no.5
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• pp.183-187
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• 2007

Compounds of multiferroic materials $YMn_{2-x}Fe_xO_5$ (x = 0.00, 0.01) were prepared using the sol-gel method. The crystallographic, magnetic and electric properties are studied using x-ray diffraction (XRD), neutron diffraction, vibrating sample magnetometer (VSM) and physical property measurement system (PPMS). The crystalline structure of $YMn_2O_5$ was found to be orthorhombic (Pbam) at room temperature. The lattice constants of $YMn_2O_5$ were determined to be $a_0=7.275\;{\AA},\;b_0=8.487\;{\AA},\;c_0=5.674\;{\AA}$. The lattice constants not changed with Fe concentrations. Our data demonstrate the correlation of magnetic and electric properties in $YMn_2O_5$ materials.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.314-319
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• 2013

In this study, nitrogen doped $TiO_2$ ($N-TiO_2$) coated on an activated carbon pellet (ACP) was prepared using sol-gel and the solid state heat treatment of urea to improve the removal property of volatile organic compounds (VOCs). To explore the visible light photocatalytic activity of the ACP under the light emitting diods (LED), the removal property of benzene gas was characterized by gas chromatography. The SEM and BET results show that the increment of titanium tetra isopropoxide contents leads to the increased $TiO_2$ coating amount of ACP surface and decreased specific surface area. From the results of benzene gas removal, the breakthrough time of ACP10 increased about 2 times compared to that of the ACP. The improved performance was attributed to the $N-TiO_2$ coating on ACP surface, which could be more effective to remove benzene gas under the condition of LED lamp.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.10a
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• pp.39-41
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• 2011

The recycling rate of recovered paper in Korea is the highest in the world, 92%, but remanufacturing yield is low due to the extremely poor quality of the paper. The poor quality, in turn, influences to the reject amount in deinking process. To increase the yield of old newspaper recycling process, hydrophobic degree of inorganic pigments of deinking stock must be reduced. To determine the hydrophobicity, Pitch Potential Deposit Tester (PDT) was newly designed and applied with respect to the SB latex property of various quality used in Korea; its hydrophobic degree according to Tg, gel content, charge and particle size of latex and optimum designing condition of SB latex. And below are the conclusions: 1. The reason of excessive reject from old newspaper deinking process for total amount of printed ink is loss of inorganic pigments. When lipase, a biochemical catalyst, was applied with the purpose of preventing inorganic pigments loss about more than 70% of total reject weight and promoting hydration of pulp for deinking, deinking process yield of pre flotation secondary stage increased remarkably without any changes of deinking efficiency. 2. Lipase improved deinking stock by cutting ester linkage on surface of hydrophobic materials to promote its hydration. From this, it reached the conclusion that hydration degree of stock exercises significant effect on flotation deinking process yield. 3. Inorganic alkali promotes hydration of deinking stock. But there have been needs for more fundamental measures other than inorganic alkali of promoting hydration for yield improvement. For this, this study intended to find out reasons of chemical properties change on surface of hydrophobic material by change of pH. 4. Pitch Deposit Test (PDT) was performed for understanding principle of why surface of coating flake from OMG is hydrophobic and why it becomes hydrophilic when pH of stock is alkaline. As a result of this test, it is determined that swelling property by change of pH of latex film, which were used as coating adhesive is the reason for hydrophobic change. 5. Hydrophilicity of coating flake increased with hydrophilic pigments. And as more of SB Latex adhesive was used and higher of calcium hardness of stock became, its hydrophilicity decreased. SB Latex adhesive film is reformed by mechanical friction. For having hydrophilicity under neutral pH, strong bruising action such as kneading is required. 6. Because swelling of adhesive film decreases as Tg of SB latex gets lower and mean diameter gets smaller, it shows hydrophobicity under neutral pH. This lowers hydrophilicity of coating flake, which leads to easy elimination with flotation reject on DIP process. Therefore, for improving future flotation yield, it is necessary to develop to use eco-friendly clean SB latex by raising Tg and increasing mean diameter for recycling, and as a result, to reduce excessive loss of coating flake as a reject from deinking process.

• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.337-344
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• 1996

Gel-type yogurt was prepared from egg white powder (EWP), casein and glucose. The effects of EWP on acid production and growth of Lactobacillus were studied. The effect of EWP on sensory properties and volatile aroma compounds were also studied. Acid production by Lactobacillus in EWP (1-3%, W/V) was significantly lower than that by Lactobacillus in milk (control). However, the increase of EWP content from 1 to 3% increased acid production significantly, Number of viable cells of L. acidophilus at 24 hrs in milk and EWP containing samples (1-3%) was $3.1{\times}10^4/ml\;and\8.3{\times}10^7-3.6{\times}10^2/ml.$ respectively Sample containing lower amount of EWP generally showed lower number of viable cells. Sensory property of EWP samples (1-3%) was showed lower than that of milk yogurt (reference). However, sensory property of samples containing EWP 2% or 3% was significantly better than that of sample containing EWP 1%. Though the composition of volatile aroma compounds was slightly different from sample to sample, gas chromatographic analysis detected acetone, ethanol, diacetyl and acetoin in samples fermented by L. acidophilus.

• Resources Recycling
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• v.23 no.1
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• pp.48-57
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• 2014

In this study, we have investigated the influence of the nature of solvent on the grafting reaction of maleic anhydride onto polyethylene wax obtained as a by-product in a high density polyethylene plant. The results show that the grafting ratio in xylene as a solvent was higher than toluene. This is because xylene has excellent monomer solubility, swelling property and miscibility. It has been also observed that grafting degree shows an initial jump in percentage of grafting with increasing amount of solvent, from 0% v/w to 200% v/w giving maximum grafting in 200% v/w and then slightly decreases on further increase in the amount of solvent and becomes almost constant. It can be also seen that gel content was not formed under the use of solvent. It means that solvent prevented cross-linking reaction due to chain transfer reactions to solvent molecules. Studies of melt viscosity at $140^{\circ}C$ showed that viscosity increased after grafting of maleic anhydride onto polyethylene wax.

• Food Science of Animal Resources
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• v.37 no.2
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• pp.228-241
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• 2017

Hematological, chemical and functional characteristics of porcine, chicken and duck blood were evaluated. A porcine blood sample showed the most abundant red blood cell, hemoglobin concentration, packed cell volume and plasma protein content as well as its freeze-dried blood possessed the highest contents of protein, fat, Cu and Cr with the highest percentage of heme iron (p<0.05). Unlike porcine blood, chicken blood showed a well balance in some essential amino acids, specifically for a higher isoleucine content (p<0.05). Furthermore, it possessed the highest contents of carbohydrate, Zn and non-heme iron (p<0.05). The most rapid response to form a strong gel, especially at $70^{\circ}C$ and $80^{\circ}C$, was found in chicken blood, followed by duck and porcine blood, respectively. The result of emulsion activity index (EAI) and emulsion stability index (ESI) at the low protein concentration indicated that chicken blood had the most superior emulsion properties (p<0.05). Regarding duck blood, it exhibited the highest content of Mg and Mn (p<0.05). Moreover, duck blood had similar foaming properties to porcine blood in which they showed higher values than chicken blood (p<0.05). Specific characteristics of blood were therefore diminished by animal species in which this information could be used as food supplementation or product development based on their potential applications.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.791-797
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• 1998

As organosilicon based preceramic polymer, new zirconium hybridized polycarbosilane having a good thermal stability and forming stage was synthesized. Oxidative stability(infusibility) and mechanical property of this polymer during the thermal curing process and heat treatment were examined. Prepared zirconium hybridized polycarbisilane (PZC) was spun into fiber at $250{\sim}270^{\circ}C$. Spinnability of PZC polymer having a molecular weight of 1000 to 1400 and having a dispersity<2 was good. The thermal curing process of the PZC fiber was done at 140 to $200^{\circ}C$. The mechanical properties of PZC ceramic fiber depend on curing temperature of PZC as precursor of PZC ceramic fiber. It was found that the optimum curing temperature was variable with the molecular weight of PZC. The cured PZC fiber need constant gel fraction to have good tensile strength.

• Journal of Microbiology and Biotechnology
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• v.4 no.2
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• pp.113-118
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• 1994

A bacterial strain NS-83 isolated from soil was able to produce an extracellular thermostable protease. The strain was identified as Pseudomonas aeruginosa based on its morphological and physiological characteristics. A thermostable protease from this strain has been purified to homogeneity as judged by SDS-PAGE and isoelectric focusing. The purification procedures included hydrophobic interaction, ion exchange, and gel filtration chromatography. The $M_r$ and the pl of the enzyme were 32,000 and 5.9, respectively. The optimal pH at 55$^{\circ}C$ and the optimal temperature at pH 7.0 were 8.0 and 60$^{\circ}C$, respectively. The D-values of the enzyme at 60, 65, and 70$^{\circ}C$ were 22, 2.1, and 0.75 hrs, respectively. The enzyme activity was significantly inhibited in the presence of 1 mM o-phenanthroline or EDTA, suggesting that the enzyme is metalloprotease. The $K_m$, and $V_{max}$ for Hammarsten casein were found to be 3.2 mg/ml and 0.918 unit/ml, respectively. These enzymatic properties were similar to those of elastase produced from P. aeruginosa IFO 3455, but the enzyme was clearly different from the reported elastase, in respect to $Ca^{++}$ effects on enzyme-thermostability. This property, together with amino acid composition analysis, confirmed that the enzyme differs from the known P. aeruginosa elastase.

• Journal of the Korean Chemical Society
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• v.44 no.1
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• pp.60-67
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• 2000

The wavelength of the surface plasmon absorption depends on the dielectric matrix. $TiO_2/SiO_2$ complex oxide films doped with Au nanoclusters were prepared by sol-gel spin-coating method using $Ti(OPr^i)_4$, $Si(OEt)_4$, and $HAuCl_4{\cdot}7H_2O$. The wavelength of the maximum absorption of Au nanoehrsters in the $TiO_2/SiO_2$ thin films was obtained with lineality from 540 nm to 615 nm depending on the molar ratio of $TiO_2$. The particle sizes and structures of these nanoclusters have been identified through a TEM and X-ray diffraction patterns. The dielectric constants of $TiO_2/SiO_2$ thin films were calculated from the experimental results.