• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.700-704
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• 2009

A simulation study on SCR(steam carbon dioxide reforming) in gas-to-liquid(natural gas to Fischer-Tropsch synthetic fuel) process was carried out in order to find optimum reaction conditions for SCR experiment. Optimum operating conditions for SCR process were determined by changing reaction variables such as temperature and $CH_4/steam/CO_2$ feed ratio. Simulation was carried out by Aspen Plus. During the simulation, overall process was assumed to proceed under steady-state conditions. It was also assumed that physical properties of reaction medium were governed by RKS(Redlich-Kwong-Soave) equation. Optimum simulation variables such as temperature and feed ratio were determined by considering $H_2/CO$ ratio for FTS(Fischer-Tropsch synthesis), $CH_4$ conversion, and $CO_2$ conversion. Simulation results showed that optimum reaction temperature and $CH_4/steam/CO_2$ feed ratio in SCR process were $850^{\circ}C$ and 1.0/1.6/0.7, respectively. Under optimum temperature of $850^{\circ}C$, $CH_4$ conversion and $CO_2$ conversion were found to be 99% and 49%, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.268-273
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• 2014

$Y_2O_3$ ceramic specimens were fabricated from the granular powder, obtained by spray drying process from the slurry. The slurry was prepared by mixing PVA binder, NaOH for Ph control, PEG and $Y_2O_3$ powder. The $Y_2O_3$ specimen was shaped in size of ${\phi}14mm$ and then sintered at $1650^{\circ}C$. The characteristics, microstructure, densities and plasma resistance of the $Y_2O_3$ specimens were investigated with the function of forming pressure and sintering time. $Y_2O_3$ specimens were exposed under the $CHF_3/O_2/Ar$ plasma, the dry etching treatment of specimens was carried out by the physical reaction etching of $Ar^+$ ion beam and the chemical reaction etching of $F^-$ ion decomposed from $CHF_3$. With increasing sintering time, $Y_2O_3$ specimens showed relatively high density and strong resistance in plasma etching test.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.4
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• pp.494-499
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• 2010

In this study, Sargassum coreanum was enzymatically hydrolyzed to prepare water-soluble extracts by using five carbohydrates (Viscozyme, Celluclast, AMG, Termamyl and Ultraflo) and five proteases (Protamex, Kojizyme, Neutrase, Flavozyme and Alcalase) and their potential antioxidant activity were evaluated. The Celluclast and Neutrase extracts of Sargassum coreanum exhibited better DPPH radical scavenging activities (92.42% and 92.78%, respectively) and hydrogen peroxide ($H_2O_2$) scavenging activities (58.28% and 57.97%, respectively) compared to those of other enzymatic extracts. These results suggest that Sargassum coreanum would be a good raw materials for antioxidant and enzymatic hydrolysis would be a good strategy to prepare antioxidant extracts from seaweeds.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.5
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• pp.509-515
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• 2012

In this study, ${\gamma}-Al_2O_3$ nanoparticles were synthesized by using coflow hydrogen diffusion flames. The synthesis conditions were varied with using several oxygen concentrations in the oxidizing air. The particle characteristics of the flame-synthesized $Al_2O_3$ nanoparticles were determined by examining the crystalline structure, shape, and specific surface area of the nanoparticles. The measured maximum centerline temperature of the flames ranged from 1507.8 K to 1998.7 K. The morphology and crystal structure of the $Al_2O_3$ nanoparticles were determined from SEM images and XRD analyses, respectively. The particle sizes were calculated from measured BET specific surface areas and ranged from 25 nm to 52 nm. From XRD analyses, it was inferred that a large number of the synthesized nanoparticles were ${\gamma}-Al_2O_3$ nanoparticles including ${\theta}-Al_2O_3$ nanoparticles.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.104-104
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• 2017

Sorghum (Sorghum bicolor (L.) Moench.) is one of the most important crops for human and animal nutrition. Nonetheless, sorghum has a cyanogenic glucoside compound which can be degraded into hydrogen cyanide, toxic to humans and animals even with tiny amount. In consequence, breeding materials with a low cyanide level has been a top priority in sorghum breeding programs. To fulfill our long-term goal, we are screening sorghum accessions with low cyanide level, which would be an important breeding material for food safety. We collected seeds of various sorghum accessions and analyzed relevant metabolites to find useful breeding materials of sorghum accessions containing low cyanide. Fourteen wild relatives were obtained from the University of Georgia in US, a reference accession BTx623, and three local varieties from National Agrobiodiversity Center of Rural Development Administration in Korea, and one wild species from the Wild Plant Resources Seed Bank of Korea University in Korea. Sorghum plants were grown in plastic greenhouse under natural conditions. After growing, leaf samples were harvested at different developmental stages: seedling phase, vegetative phase (right before flowering), and reproductive phase (ripening). Using collected samples, quantification analysis were performed by an HPLC system for three metabolites (dhurrin, 4-hydroxybenzaldehyde, and 4-hydroxyphenylacetic acid) in sorghum plants. Prior to metabolome analysis, specific experimental condition for HPLC system was set to be able to separate three metabolites simultaneously. Under this condition, these metabolites were quantified in each accession by HPLC system. We observed that the metabolite contents were changed differently by developmental stages and accessions. We clustered these results into five groups as patterns of their contents by developmental stages. Most of accessions showed that 4-hydroxybenzaldehyde content was very high at seedling stage and decreased rapidly at vegetative phase. Interestingly, the patterns of dhurrin content were very different among clusters. However, 4-hydroxyphenylacetic acid content was maintained at low levels by developmental stages in most accessions. The results would demonstrate how dhurrin and alternative degradation pathways are differentiated in each accession.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.3
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• pp.122-126
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• 2012

The properties of Al-doped ZnO (AZO) films were investigated as a function of $H_2/(Ar+H_2)$ gas ratio using an AZO (2 wt% $Al_2O_3$) ceramic target in a radio frequency (RF) magnetron sputtering system. The deposition process was done at $200^{\circ}C$ and in $2{\times}10^{-2}$ Torr working pressure and with various ratios of $H_2/(Ar+H_2)$ gas. During the AZO film deposition process, partial $H_2$ gas affected the AZO film characteristics. The electron resistivity (${\sim}9.21{\times}10^{-4}\;{\Omega}cm$) was lowest and mobility (${\sim}17.8\;cm^2/Vs$) was highest in AZO films when the $H_2/(Ar+H_2)$ gas ratio was 2.5 %. When the $H_2/(Ar+H_2)$ gas ratio was increased above 2.5 %, the electron resistivity increased and mobility decreased with increasing $H_2/(Ar+H_2)$ gas ratio in AZO films. The carrier concentration increased with increasing $H_2/(Ar+H_2)$ gas ratio from 0 % to 7.5 %. This phenomenon was explained by reaction of hydrogen and oxygen and additional formation of oxygen vacancy. The average optical transmission in the visible light wavelength region over 90 % and an orientation of the deposition was [002] orientation for AZO films grown with all $H_2/(Ar+H_2)$ gas ratios.

• Korean Journal of Microbiology
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• v.45 no.1
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• pp.17-25
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• 2009

We studied soil components, methane production, the number of methanogens, and T-RFLP patterns dependent on agricultural methods with the change of seasons. There is no regular increase or decrease tendency of the most soil components followed by sampling period. And the water content in soil was higher in October than May. Also a lot of methanogens existed in soil, and acetotrophs were relatively of smaller number than hydogenotrophs and formate utilizing methanogens using MPN (most probable number) enumeration. In the experiment using the formate, it was used from the first week, and only a minute amount was detecte after four weeks. However in the acetate, it was increased until the third week, and after that was consumed. And there was higher methane production for all soil samples which administered with the hydrogen spike. The activity of methanogens was higher in the organic and low-agrichemical agricultural method samples, and the organic agricultural method had high methanogen activity among the other samples. A result of T-RFLP pattern of mcrA gene digested with Sau96I, methanogen community have a little relation with agricultural methods and seasons. This results also agreed to no critical difference the soil components dependent on agricultural methods, but some analytical data have a positive relationship with a agricultural methods. Therefor we could concluded that the comparison study of community for soil bacteria sufficiently could be useful for the microbiological indicator.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.292-302
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• 2009

The wet oxidation of phenol has been investigated at temperatures from 150 to $250^{\circ}C$ and oxygen partial pressures from 25.8 to 75.0 bar with initial pH of 1.0 to 12.0 and initial phenol concentration of 10 g/l. Chemical Oxygen Demand COD has bee measured to estimate the oxidation rate. Reaction intermediates have been identified and their concentration profiles have been determined using liquid chromatography. The destruction rate of phenol have shown the first-order kinetics with respect to phenol and the changes in COD during wet oxidation have been described well with the lumped model. The impact of various homogeneous catalysts, such as $Cu^{2+}$, $Fe^{2+}$, $Zn^{2+}$, $Co^{2+}$ and $Ce^{3+}$ ions, on the destruction rate of phenol and COD has also been studied. The homogeneous catalyst of $CuSO_4$ has been found to be the most effective for the destruction of phenol and COD during wet oxidations. The destruction rate of formic acid formed during wet oxidations of phenol have increased as increasing temperature and $CuSO_4$ concentration. The final concentrations of acetic acid which has been formed during wet oxidations and difficult to oxidize have increased with reaction temperature and with decrease in the catalyst load.

• The Korean Journal of Pesticide Science
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• v.13 no.2
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• pp.63-69
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• 2009

New morpholinylcarbonylmethyl-2-phenylimino-1,3-thiazolines 2(X=O) and piperidinylcarbonylmethyl-2-phenylimino-1,3-thiazolines 3(X=C) to which morpholinyl or piperidinyl functional group were introduced at C-4 side chain of the 2-phenylimino-1,3-thiazoline scaffold were synthesized to investigate the effect of NH hydrogen of 2-phenylimino-1,3-thiazoline-4-acetanilide derivatives on the antifungal property against rice blast. Synthesized 30 compounds were screened against 6 kinds of typical plant fungi. Treatment of ketene dimer with chlorine followed by the reaction of morphorine or piperidine without isolation of the intermediate acetoacetylchloride gave $\gamma$-chloro-$\beta$-keto derivatives. These were reacted with thioureas to give morpholinylcarbonylmethyl-2-phenylimino-1,3-thiazolines and piperidinylcarbonylmethyl-2-phenylimino-1,3-thiazolines respectively in good yield (27-98%). The compound 3j, in which two fluorine atoms are substituted at ortho and para position of phenyl group of 2-phenylimino moiety and piperidinyl group is substituted at C-4, showed the highest antifungal activity (100 ppm, 90%). This result suggested that the substituent at C-4 of the 2-phenylimino-1,3-thiazolines may play a supplementary role to show the antifungal activity against rice blast.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.486-492
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• 2009

Wet oxidations (WO) of quinoline in aqueous solution were carried out at $225^{\circ}C$ and $250^{\circ}C$. In the WO at $250^{\circ}C$, quinoline was degraded completely within 30 min and the reduction in total organic carbon (TOC) of 63% was achieved during 120 min. However, the rate of the reduction in TOC was only 13% within 240 min during the WO at $225^{\circ}C$. Nicotinic and acetic acid were found to be main intermediates formed during the oxidation of quinoline. With the addition of the homogeneous catalyst $CuSO_4$ or more easily oxidizable phenol, WOs of quinoline were also carried out under moderate conditions at $200^{\circ}C$. The catalytic WO with $CuSO_4$ of 0.20 g/L showed the destruction rates of quinoline and TOC comparable to those in the WO at $250^{\circ}C$. The WOs of quinoline-phenol mixture exhibited induction periods to degrade quinoline and phenol during which free radicals were produced to initiate WOs. With increasing initial concentrations of phenol at a given initial concentration of quinoline, the induction periods in the destructions of quinoline and phenol became shorter and the reduction in TOC increased from 60% to 75% during 180 min of the WOs. The reduction rate of an induction period decreased as increasing the initial concentration ratio of phenol to quinoline. On the other hand, phenol degradation in the WOs of quinoline-phenol mixtures required a longer induction period and proceeded slower compared to the case of the WO of phenol.