• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.420-425
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• 2006

Nano sized mixed metal hexagonal ferrite powders with improved magnetic properties have been prepared by sol-gel method using propylene oxide as a gelation agent. To obtain the desired ferrite, two different metal ions were used. One of the ions has only +2 formal charge. The key step in the processes is that hydrated $Ba^{2+}$ or $Sr^{2+}$ ions are hydrolyzed and condensed at the surface of the previously formed $Fe_{2}O_{3}$ gel. In this processes, all the reaction can be finished within a few minutes. The magnetic properties of the produced powder were improved by heat treatment. The highest values of the magnetic properties were achieved at temperature $150^{\circ}C$ lower than those of the previously published values. The highest observed values of coercivity and the saturation magnetization of Sr-ferrite and Ba-ferrite powder were 6198 Oe, 5155 Oe and 74.4 emu/g, 68.1 emu/g, respectively. The ferrite powder annealed at $700^{\circ}C$ showed spherical particle shapes. The resulting spheres which were formed by the aggregation of nanoparticles with size 3~5 nm have diameter around 50 nm. The powder treated at $800^{\circ}C$ showed hexagonal-shaped grains with crystallite size above 500 nm.

• Journal of Energy Engineering
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• v.29 no.1
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• pp.58-62
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• 2020

Among the exhaust gas, Carbon dioxide which is a causative factor in greenhouse effect. We study for synthesis of propylene carbonate with carbon dioxide which is captured and utilized in commercially valuable. The Experiment was proceeded as pilot scale with using homogeneous organic catalyst which is able to produce propylene carbonate in commercial and reaction conditions. Optimization condition for concentration of catalyst and reaction temperature, pressure was studied. We confirm that this process is eco-friendly method and commercial application due to the mild condition and also catalyst has a competitive price, reusability.

• Clean Technology
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• v.17 no.1
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• pp.37-40
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• 2011

Some ionic liquids are suitable for catalysts and solvents which are applicable to $CO_2$ fixation reaction converting $CO_2$ to carbonate. Using the ionic liquids, the synthesis process will become greener and simpler because of easy catalyst recycling and unnecessary use of volatile and harmful organic solvents. In this work, the synthesis of propylene carbonate from propylene oxide using carbon dioxide and ionic liquids were measured at high pressures up to ~140 bar and at temperatures between $60^{\circ}C$ and $80^{\circ}C$. As a results, we found the optimum condition and obtained the maximum yield under that condition.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.54-56
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• 2006

Single-well-gas-sparging tests were developed and evaluated for assessing the feasibility of in-situ aerobic cometabolism of trichloroethylene (TCE), using propane as a growth substrate. To evaluate transport characteristics of dissolved solutes [sulfur hexafluoride (SF6) or bromide (non-reactive tracers), propane (a growth substrate), ethylene, propylene (nontoxic surrogates to probe for CAH transformation activity), and DO], push-pull transport tests were performed. Mass balance showed about 90% of the injected bromide and about 80% of the injected SF6 were recovered, and the recoveries of other solutes were comparable with bromide and slightly higher than SF6. A series of Gas-Sparging Biostimulation tests were performed by sparging propane/oxygen/argon/SF6 gas mixtures, and temporal ground water samples were obtained from the injection well under natural gradient 'drift' conditions. The decreased time for propane depletion and the longer time to deplete SF6 as a conservative tracer indicate the progress of biostimulation. Gas-Sparging Activity tests were performed. .Propane utilization, DO consumption, and ethylene and propylene cometabolism were well demonstrated. The stimulated propane-utilizers cometabolized ethylene and propylene to produce ethylene oxide and propylene oxide, as cometabolic by-products, respectively. Gas-Sparging Acetylene Blocking tests were performed by sparging gas mixtures including acetylene to demonstrate the involvement of monooxygenase enzymes. Gas substrate degradation was essentially completely Inhibited in the presence of acetylene, and no production of the corresponding oxides was also observed. The Gas-Sparging tests supports the evidences that the successive stimulation of propane-oxidizing microorganisms, cometabolic transformation of ethylene and propylene by the enzyme responsible for methane and propane degradation.

• Macromolecular Research
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• v.16 no.5
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• pp.473-480
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• 2008

In this study we investigated bacterial and cell adhesion to poly(propylene carbonate) (PPC) films, that had been synthesized by the copolymerization of carbon dioxide (a global warming chemical) with propylene oxide. We also assessed the biocompatibility and biodegradability of the films in vivo, and their oxidative degradation in vitro. The bacteria adhered to the smooth, hydrophobic PPC surface after 4 h incubation. Pseudomonas aeruginosa and Enterococcus faecalis had the highest levels of adhesion, Escherichia coli and Staphylococcus aureus had the lowest levels, and Staphylococcus epidermidis was intermediate. In contrast, there was no adhesion of human cells (cell line HEp-2) to the PPC films, due to the hydrophobicity and dimensional instability of the surface. On the other hand, the PPC films exhibited good biocompatibility in the mouse subcutaneous environment. Moreover, contrary to expectation the PPC films degraded in the mouse subcutaneous environment. This is the first experimental confirmation that PPC can undergo surface erosion biodegradation in vivo. The observed biodegradability of PPC may have resulted from enzymatic hydrolysis and oxidative degradation processes. In contrast, the PPC films showed resistance to oxidative degradation in vitro. Overall, PPC revealed high affinity to bioorganisms and also good bio-degradability.

• Proceedings of the Korean Fiber Society Conference
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• 1996.10a
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• pp.190-194
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• 1996

• Proceedings of the Korean Fiber Society Conference
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• 1997.10a
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• pp.76-80
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• 1997

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.120-123
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• 1993

This paper describes the deposition and characteristics of electrochromic tungsten oxide thin films for electrochromic smart windows. Tungsten Oxide thin films(WO$_3$) are deposited by thermal evaporation techniques. By varying deposition parameters, WO$_3$ thin films exhibit different optical properties. The electrochromic devices are consist of ITO glass/ WO$_3$ thin films/ LiClO$_4$-propylene carbonate electrolyte/ counter electrode. The electrochromic properties of tungsten oxide thin films with different deposition condition ale investigated.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.2
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• pp.423-428
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• 1999

Potato starches were hydroxypropylated with 2.5, 5.0, 7.5, and 10.0% propylene oxide(PO) to improve mechanical properties of starch polyethylene film. Starch polyethylene cast films were prepared that contained 5% or 10% of the hydroxypropylated potato starch. Mechanical properties of these films were measured and compared to those of the films containing native potato starch. DS(degree of substitution) increased proportionally as propylene oxide concentration increased. Relative crystallinity in X ray diffraction patterns was decreased and starch granule observed by scanning electron micro scopy was destroyed by severe hydroxypropylation. In color properties of films, b value was not significantly different in the films but 5% starch polyethylene films with 2.5 PO starch showed the lowest L and a value. Tensile strength and strain energy of the films except the film containing 10.0 PO starch were higher than those of the containing native starch.

• Bulletin of the Korean Chemical Society
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• v.12 no.1
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• pp.26-31
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• 1991

Facile and efficient syntheses of terpenic perfumeries cis-jasmone, dihydrojasmone, and tetrahydrojasmone have been investigated. Cis-jasmone was synthesized by successive metallation followed by alkylation of acetone N,N-dimethylhydrazone with (Z)-2-penten-1-yl tosylate (or 2-pentyn-1-yl tosylate) and propylene oxide in one flask to give a ketonic alcohol, which was oxidized to the corresponding diketone, followed by base-catalyzed intramolecular aldol condensation to give a regioselective cyclization product. Dihydrojasmone and tetrahydrojasmone could be conveniently obtained from 2-octanone. The dimethylhydrazone of the ketone was lithiated with butyllithium and reacted with propylene oxide to give a ketonic alcohol, which was oxidized to a diketone, followed by base-catalyzed intramolecular cyclization to afford dihydrojasmone. Tetrahydrojasmone was prepared by converting the ketonic alcohol into corresponding iodoketone, followed by base-catalyzed intramolecular cycloalkylation to furnish an odoriferous product.