• Journal of Energy Engineering
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• v.25 no.4
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• pp.176-183
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• 2016

This study relates to a polymer electrolyte membrane for improved performance fuel cell, were researched with respect to properties required for driving a fuel cell. The bis(4-fluorophenyl)phenyl phosphine oxide was sulfonated using fuming sulfuric acid. Synthetic hydrophilic oligomer and the hydrophobic oligomer and the block copolymers were prepared via aromatic nucleophilic substitution polycondensation. A block copolymer structure and degree of sulfonation was analyzed by $^1H$-NMR and gel permeation chromatography(GPC) analysis. Thermal stability was confirmed by thermogravimetric analysis(TGA), block copolymer was stable at high temperature(>$200^{\circ}C$), The ion conductivity was measured in order to demonstrate the performance of fuel cell. Synthesis membrane was the increase of temperature was improved conductivity up to 58 mS/cm due to the influence of the developed ion clusters. The phase separation of the polymer was observed to make AFM analysis.

• Research in Plant Disease
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• v.7 no.1
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• pp.1-7
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• 2001

An isolate of Cucumber mosaic cucumovirus(CMV) was isolated from Hydrangea macrophylla for. otaksa(Sieb. et Zucc. ) Wils. showing mosaic symptoms, and designated as Hm-CMV. Hm-CMV was characterized by the tests of host range, physical properties, serological properties, RNA and coat protein compositions, and reverse transcription and polymerase chain reaction (RT-PCR) analysis. Twelve species in 4 families were used in the host range test of Hm-CMV and could be differentiated from Y-CMV used as a control CMV by the ringspot and line pattern on inoculated leaves of several tobacco plants. Thevirus produced local lesions on inoculated leaves of Chenopodium amarticolor, C. quinoa and Vigna unguiculata. The physical properties of the virus were as follows; thermal inactivation point(TIP) was 60$\^{C}$, dilution end point (DEP) was 10$\^$-3/, and longevity in vitro (LIP) was 3∼4 days. Hm-CMV was serologically identical to Y-CMV. SDS-polyaciylamide gel electrophoresis(SDS-PAGE) showed one major protein band of about 28 kDa. In RNA or dsRNA analysis, Hm-CMV consisted of four RNA or dsRNA species, but satellite RNA was not detected. In RT-PCR using CMV-common primer and CMV subgroup I-specific primer, bothe amplified expected size of about 490 bp and 200 bp DNA fragments from Hm-CMV, respectively. Restriction enzyme analysis of the 490 bp RT-PCR products using EcoR I and Msp I showed that Hm-CMV belonged to CMV subgroup I. However, Hm-CMV could be differentiated from other CMV subgroup I isolates by RNA fingerprinting by arbitrarily primed polymerase chain reaction (RAP-PCR).

• Polymer(Korea)
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• v.29 no.4
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• pp.350-356
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• 2005

Poly(methyl methauylate)/montmorillonite nanocomposites were incorporated into acrylic bone cement in order to improve the mechanical properties and reduce the exotherm of acrylic bone cement. The nanocomposites were prepared using a suspension polymerization and characterized by scanning electron microscopy, X-ray diffraction, trans-mission electron microscopy, gel permeation chromatography, particle size analyzer and electron dispersive spectroscopy. The acrylic bone cements with poly (methyl methacrylate)/nanocomposite s were prepared and their thermal and mechanical properties were characterized. The prepared polymeric beads were composed of polymer-intercalated nanocomposites with partially exfoliated MMT layers, and the mean diameter of them was $50\~60$ fm with the spherical shape. The maximum setting temperature of the acrylic bone cements decreased from 98 to $81\~87^{circ}C$. The mechanical strengths and moduli of the acrylic bone cement with 0.1 $wt\%$ MMT were increased. compared to that without MMT. However, the mechanical properties were generally decreased with increasing incorporated MMT amounts. It is presumably due to the bubbles in nanocomposite beads generated during polymerization.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.534-538
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• 2017

In this study, the molecular weight controlled pitches derived from pyrolyzed fuel oil (PFO) were prepared using solvent extraction and were carbonized. Electrochemical characteristics of lithium battery anode materials were investigated using these petroleum pitches. Three pitch samples prepared by the thermal reaction were 3903 (at $390^{\circ}C$ for 3 h), 4001 (at $400^{\circ}C$ for 1 h) and 4002 (at $400^{\circ}C$ for 2 h). The prepared hexane insoluble pitches were analysed by XRD, TGA, SEM and Gel permeation Chromatography (GPC). The electrochemical characteristics of the PFO-derived pitch as an anode material were investigated by constant current charge/discharge, cyclic voltammetry and electrochemical impedance tests. The coin cell using pitch (4001) and the electrolyte of $LiPF_6$ in organic solvents (EC : DMC = 1 : 1 vol%, VC 3 wt%) has better initial capacity (310 mAh/g) than that of other pitch coin cells. Also, this carbon anode showd a high initial efficiency of 82%, retention rate capability at 2 C/0.1 C of 90% and cycle retention of 85%. It was found that modified pitches improved the cycling and rate capacity performance.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.308-313
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• 1999

Total polar lipid produced from the soybean oil and lard by heating with different surface area at $185^{\circ}C$ were measured by silica gel column chromatography. Further, the polar lipid was fractionated by high performance size exclusion chromatography-evaporative light scattering detector (HPSEC-ELSD). The HPSEC system was composed of two GPC columns $(100\;{\AA}\;and\;500\;{\AA})$ and a THF mobile phase. With this system it was possible to fractionate into the free fatty acid, diglyceride, triglyceride monomer, triglyceride dimer and triglyceride polymers. The triglyceride monomer, triglyceride dimer and triglyceride polymers significantly increased as the heating time and surface area increased. But diglyceride and free fatty acid did not increased as the heating time and surface area increased. Triglyceride polymer (r>0.93), triglyceride dimer (r>0.97), triglyceride monomer (r>0.95) showed a high correlation with polar lipid content. On the other hand, diglyceride (r<0.68) and free fatty acid (r<0.76) were not significantly correlated with the polar lipid content. These results indicated that a major oxidative components formed during thermal oxidation were triglyceride polymers and triglyceride dimer and triglyceride monomer.

• Korean journal of applied entomology
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• v.23 no.1 s.58
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• pp.15-21
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• 1984

The virus infecting French bean (Phaseolus vulgaris L.) was identified as Bean Common Mosaic Virus(BCMV) based on the host range, symptomatology, serology, morphology of virus particles and inclusion bodies. Isolates of BCMV were obtained from seeds of P. vulgaris collected at Suweon, Jangsu and Jinju in Korea. French bean produced vein clearing, mosaic, stunting and leaf curling. Symptom of Chenopodium quinoa was local lesions on the inoculated leaves, not on the upper leaves. The electron micrograph of the virus from French bean was flexuous approximately 750nm in length. Cylindrical and pinwheel cytoplasmic inclusion bodies were observed in French bean leaf infected by BCMV. BCMV from the French bean was transmitted through seed and green peach aphid, Myzus persicae. The thermal inactivation point was $55\~60^{\circ}C$, dilution end point was $10^{-3}\~10^{-5}$ and longevity in vitro was $2\~3$ days for BCMV from French bean. The isolates of BCMV reacted positively against BCMV antiserum. The extract of BCMV infected bean leaves, Azukibean mosaic virus (AZMV) and Cowpea aphid borne mosaic virus(CaMV) also reacted with BCMV antiserum, however, BCMV and CaMV showed the spur in agar gel diffusion test.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.65-65
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• 2012

Copper zinc tin sulfide ($Cu_2ZnSnS_4$, CZTS) is a very promising material as a low cost absorber alternative to other chalcopyrite-type semiconductors based on Ga or In because of the abundant and economical elements. In addition, CZTS has a band-gap energy of 1.4~1.5eV and large absorption coefficient over ${\sim}10^4cm^{-1}$, which is similar to those of $Cu(In,Ga)Se_2$(CIGS) regarded as one of the most successful absorber materials for high efficient solar cell. Most previous works on the fabrication of CZTS thin films were based on the vacuum deposition such as thermal evaporation and RF magnetron sputtering. Although the vacuum deposition has been widely adopted, it is quite expensive and complicated. In this regard, the solution processes such as sol-gel method, nanocrystal dispersion and hybrid slurry method have been developed for easy and cost-effective fabrication of CZTS film. Among these methods, the hybrid slurry method is favorable to make high crystalline and dense absorber layer. However, this method has the demerit using the toxic and explosive hydrazine solvent, which has severe limitation for common use. With these considerations, it is highly desirable to develop a robust, easily scalable and relatively safe solution-based process for the fabrication of a high quality CZTS absorber layer. Here, we demonstrate the fabrication of a high quality CZTS absorber layer with a thickness of 1.5~2.0 ${\mu}m$ and micrometer-scaled grains using two different non-vacuum approaches. The first solution-processing approach includes air-stable non-toxic solvent-based inks in which the commercially available precursor nanoparticles are dispersed in ethanol. Our readily achievable air-stable precursor ink, without the involvement of complex particle synthesis, high toxic solvents, or organic additives, facilitates a convenient method to fabricate a high quality CZTS absorber layer with uniform surface composition and across the film depth when annealed at $530^{\circ}C$. The conversion efficiency and fill factor for the non-toxic ink based solar cells are 5.14% and 52.8%, respectively. The other method is based on the nanocrystal dispersions that are a key ingredient in the deposition of thermally annealed absorber layers. We report a facile synthetic method to produce phase-pure CZTS nanocrystals capped with less toxic and more easily removable ligands. The resulting CZTS nanoparticle dispersion enables us to fabricate uniform, crack-free absorber layer onto Mo-coated soda-lime glass at $500^{\circ}C$, which exhibits a robust and reproducible photovoltaic response. Our simple and less-toxic approach for the fabrication of CZTS layer, reported here, will be the first step in realizing the low-cost solution-processed CZTS solar cell with high efficiency.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.363-370
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• 2016

Lightweight geopolymers are more readily produced and give higher fire resistant performance than foam cement concrete. Lowering the density of solid geopolymers can be achieved by inducing chemical reactions that entrain gases to foam the geopolymer structure. This paper reports on the effects of adding different concentrations of aluminum powder on the properties of cellular structured geopolymers. The apparent density of lightweight geopolymers has a range from 0.7 to $1.2g/m^3$ with 0.025, 0.05 and 0.10 wt% of a foaming agent concentration, which corresponds to about 37~60 % of the apparent density, $1.96g/cm^3$, of solid geopolymers. The compressive strength of cellular structured geopolymers decreased to 6~18 % of the compressive strength, 45 MPa of solid geopolymers. The microstructure of geopolymers gel was equivalent for both solid and cellular structured geopolymers. The workability of geopolymers with polyprophylene fibers needs to be improved as in fiber-reinforced cement concrete. The lightweight geopolymers could be used as indoor wall tile or board due to fire resistance and incombustibility of geopolymers.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.418-424
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• 2016

This study is an experimental study on the recycling of bottom ash in coal ash discharged from a thermal power plant. Bottom ash has limited research on recycling because it has more porous and higher water absorption ratio than fly ash. In this paper, the bottom ash was pulverized to a specific surface area of $4,000cm^2/g$ in order to use as a binder, and the flow, compressive strength test and microstructure analysis of the bottom ash based geopolymer mortar were performed. The flow measurement results of the geopolymer mortar showed that the flow rate was improved by increasing mixing water as the molar concentration of activator was increased. Compressive strength increased with increasing curing temperature and molar concentration. Through the microstructure analysis, we could confirm the geopolymer gel produced by the reaction of the condensation polymerization. It is considered that it is possible to make the bottom ash based geopolymer concrete through proper molar concentration of activator and high temperature curing.

• Journal of the Korean Electrochemical Society
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• v.3 no.3
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• pp.146-151
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• 2000

So fine cobalt oxide xerogel powders were prepared by using a unique solution chemistry associated with the sol-gel process. The effect of thermal treatment on the crystalinity, particle structure, and corresponding electrochemical properties of the resulting xerogel remained amorphous as $Co(OH)_2$ up to $160^{\circ}C$ With an increase in the temperature above $200^{\circ}C$, both the surface area and pore volume decreased sharply, because the amorphous $Co(OH)_2$ decomposed to form CoO that was subsequently oxidized to form crystalline Co304. In addition, the changes in the crystallinity, and particle structure all had significant but coupled effects on the electrochemical properties of the xerogels. A maximum capacitance of 192F1g was obtained for an electrode prepared with the $CoO_x$ Xerogel calcined at$150^{\circ}C$, which was consistent with the maxima exhibited in both the surface area and pore volume. This capacitance was attributed solely to a surface redox mechanism.