• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.665-672
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• 1997

We applied mechanical alloying process by ball milling to produce molybdenum silicides $MoSi_2$ and $Mo_5Si_3$ using a mixture of elemental molybdenum and silicon powders at room temperature. The intermetallic compound MoSi$_3$ have been obtained by ball milling of $Mo_{33}Si_{67}$ mixture powders for 100 h, which is transformed to single $MoSi_2$ phase by subsequent heat treatment up to $725^{\circ}C$. The grain size of the $MoSi_2$ powders thus obtained was 19 nm, being approximately four times smaller than that of the commercial alloy. The intermetallic compound $MoSi_2$ with grain size of 30 nm have been also obtained by ball milling of $Mo_{62}Si_{38}$ mixture powders for 500 h, which is transformed to single $MoSi_2$ phase by heating up to $1000^{\circ}C$. We believe that the retarded ball milling time for the formation of $MoSi_2$ phase is attributed to its complicated crystal structure and large unit cell. The finer grain size in the ball-milled molybdenum silicides powders is expected to improve room-temperature mechanical properties for high-temperature structural materials.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.234-238
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• 2015

The separation of nitrogen heterocyclic compound (NHC) contained in a model coal tar fraction was compared by the methanol and formamide extraction. The model coal tar fraction comprising four kinds of NHC (NHCs : quinoline, iso-quinoline, indole, quinaldine) and three kinds of bicyclic aromatic compound (BACs : 1-methylnaphthalene, 2-methylnaphthalene, dimethylnaphthalene), biphenyl and phenyl ether was used as a raw material. The aqueous solution of methanol and formamide were used as solvents. A batch-stirred tank was used as the raw material - a solvent contact unit of this work. Independent of the solvent used, the distribution coefficient of NHCs sharply increased by decreasing the initial volume ratio of water to the solvent and increasing the equilibrium operation temperature, whereas, the selectivity of NHCs in reference to BACs decreased. Decreasing the initial volume ratio of solvent to feed resulted in deteriorating distribution coefficients, but the selectivity of NHCs in reference to BAC was almost the constant. The distribution coefficient of NHCs by the methanol extraction was 3~5 times higher than that of NHCs by the formamide extraction, inversely, the selectivity of NHCs based on BACs by the formamide extraction was 3~7 times higher than that of NHCs by the methanol extraction. Furthermore, two different solvent extraction methods by adding the extraction processing speed to the balance between solvency and selectivity of NHCs were compared.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.5
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• pp.374-380
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• 2014

To estimate greenhouse gas (GHG) emission, the inventory of rice cultivation at the farming without agricultural chemicals was established from farmers in Gunsan, Jeonbuk province in 2011~2012. The objectives of this study were to calculate carbon footprint and analyse the major factor of GHGs. To do this, we carried out a sensitivity analysis using the analyzed main factors of GHGs and estimated the mitigation potential of GHGs. Also we suggested agricultural methods to reduce GHGs that can be appled by farmers at this region. At the farming system without agricultural chemicals, carbon footprint of rice production unit of 1 kg was 2.15 kg $CO_2.-eq.kg^{-1}$. Although the amount of carbon dioxide ($CO_2$) emission was the largest among GHGs, methane ($CH_4$) emission had the highest contribution to carbon footprint on rice production system when it was converted to carbon dioxide equivalent ($CO_2-eq.$) multiplied by the global warming potential (GWP). Main source of $CO_2$ emission in the rice farming system without agricultural chemicals was combustion of fossil fuels used by agricultural machinery. Most of the $CH_4$ was emitted during rice cultivation practice and its major emission factor was flooded paddy field in anaerobic condition. Also, most of the $N_2O$ was emitted from rice cultivation process. Major sources of the $N_2O$ emission was application of fertilizer such as compound fertilizer. As a result of sensitivity analysis in energy consumption, diesel had the highest sensitivity among the energy inputs. With the reduction of diesel consumption by 10%, it was estimated that $CO_2$ potential reduction was about 2.0%. With reducing application rate of compound fertilizer by 10%, the potential reduction was calculated that $CO_2$ and $N_2O$ could be reduced by 0.5% and 0.9%, respectively. At the condition of 10% reduction of silicate and compost, $CO_2$ and $CH_4$ could be reduced by 1.5% and 1.6%, respectively. With 8 days more drainage than the ordinary practice, $CH_4$ emission could be reduced by about 4.5%. Drainage and diesel consumption were the main sources having the largest effect on the GHG reduction at the farming system without agricultural chemicals. Based on the above results, we suggest that no-tillage and midsummer drainage could be a method to decrease GHG emissions from rice production system.

• Journal of Life Science
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• v.30 no.5
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• pp.452-459
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• 2020

This study was conducted to investigate the total lignin content and anti-oxidant activity in extracts of defatted sesame seeds (DSS) fermented with 15 strains of Bacillus subtilis. The anti-oxidant activities of DSS were analyzed both before and after fermentation. The total lignan content of the DSS extracts fermented with BCH3678 (1,613.8 mg/l) and BCH3572 (1,599.5 mg/l) were relatively high compared to other strains. Anti-oxidant activity was determined according to phenolic compound and flavonoid content and DPPH radical scavenging rate; the highest total phenolic compound content was provided by the DSS with SRCM103716 at 2,803.3 mg GAE/g which returned total flavonoid content of 1,553.1 mg/g as strong correlation of its anti-oxidant activity. The DSS extract fermented by SRCM103716 at 37℃ for 24 hr showed the highest DPPH scavenging rate at 66.5%. The fermented DSS extracts, regardless of strain, demonstrated higher anti-oxidative activity than the unfermented control, and these results suggest that such extracts could be useful as a potential source of bioactive compounds.

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1067-1074
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• 1995

Reaction of arachno-S2B7H8- with either THF or 1,2-dimethoxyethane upon refluxing condition results in the formation of the previously known compound hypho-S2B7H10-. Protonation of hypho-S2B7H10- with HCl/Et2O generates hypho-2,5-S2B7H11 in good yield. This hypho-S2B7H10- anion has been employed to generate a series of new nido-, arachno-, and hypho-metalladithiaborane clusters. Reaction of the anion with Cp(CO)2FeCl results in direct metal insertion and the formation of a complex containing the general formula (η5-C5H5)FeS2B7H8. Spectroscopic studies of nido-6-CpFe-7,9-S2B7H8 Ⅰ demonstrated that compound Ⅰ was shown to have an nido-type cage geometry derived from an octadecahedron missing one vertex, with the iron atom occupying the three-coordinate 6-position in the cage and the two sulfurs occupying positions on the open face of the cage. Reaction of hypho-S2B7H10- with CoCl2/Li+[C5H5]- gave the previously known complex arachno-7-CpCo-6,8-S2B6H8 Ⅱ. Also, the reaction of the anion with [Cp*RhCl2]2 gave the complex arachno-7-Cp*Rh-6,8-S2B6H8 Ⅲ, the structure of which was shown to be that of complex Ⅱ. The similarity of the NMR spectra of Ⅱ and Ⅲ suggest that Ⅲ adopts cage structure similar to that previously confirmed for Ⅱ. A series of 9-vertex hypho clusters in which the sulfur atoms are bridged by different species isoelectronic with a BH3 unit, such as HMn(CO)4 or SiR2 have been prepared. Compounds Ⅳ,Ⅴ and Ⅵ are each 2n+4 skeletal electron systems and would be expected according to skeletal electron counting theory to adopt hypho-type polyhedral structures derived from an icosahedron missing three vertices. The complex hypho-1-(CO)4Mn-2,5-S2B6H9 Ⅳ was obtained by the reaction of the anion with (CO)5MnBr and has been shown from spectroscopic data to consist of a (CO)4Mn fragment bound to the two sulfur atoms S2 and S5 of hypho-S2B7H10-. Also, similar hypho-type complexes hypho-1-R2Si-2,5-S2B6H8 (R=CH3 Ⅴ, R=C6H5 Ⅵ) have been prepared from the reaction of hypho-S2B7H10- with R2SiHCl.

• Smart Media Journal
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• v.11 no.5
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• pp.17-25
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• 2022

Korean part-of-speech taggers decompose a compound morpheme into unit morphemes and attach part-of-speech tags. So, here is a disadvantage that part-of-speech for morphemes are over-classified in detail and complex word types are generated depending on the purpose of the taggers. When using the part-of-speech tagger for keyword extraction in deep learning based language processing, it is not required to decompose compound particles and verb-endings. In this study, the part-of-speech tagging problem is simplified by using a Head-Tail tokenization technique that divides only two types of tokens, a lexical morpheme part and a grammatical morpheme part that the problem of excessively decomposed morpheme was solved. Part-of-speech tagging was attempted with a statistical technique and a deep learning model on the Head-Tail tokenized corpus, and the accuracy of each model was evaluated. Part-of-speech tagging was implemented by TnT tagger, a statistical-based part-of-speech tagger, and Bi-LSTM tagger, a deep learning-based part-of-speech tagger. TnT tagger and Bi-LSTM tagger were trained on the Head-Tail tokenized corpus to measure the part-of-speech tagging accuracy. As a result, it showed that the Bi-LSTM tagger performs part-of-speech tagging with a high accuracy of 99.52% compared to 97.00% for the TnT tagger.

• KSBB Journal
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• v.19 no.4
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• pp.269-273
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• 2004

A simple, fast and reproducible quantitative analysis method for sugar concentration composed in oligosaccharide mixture was developed. Two glass TLC plates were prepared per sample. After dipping one plate into the copper bicinchoninate reagent and the other plate into 5% sulfuric acid solution, both plates were baked in microwave oven until sugar spots were developed or the surface temperature of TLC plate becomes 60 to 70 $^{\circ}C$. The corrective factor values [F value =(the value of total sugar concentration converted as glucose unit/the value of reducing sugar concentration converted as glucose unit)/(polymerization degree of sugar)] of different molecular weight sugars were determined. Within the concentration of 0.25∼1.0 $\mu\textrm{g}$ in each sample loaded, the fructose-F (corrective factor value of fructose) was 0.45, yet for the higher concentration (2.5∼7.5 $\mu\textrm{g}$) fructose-F was 1.0. In case of glucose, in the range of 0.5∼7.5 $\mu\textrm{g}$, glucose-F was same as fructose-F, 1.0. However, as the molecular weight of sugar was increased, the F values were decreased in both maltodextrin and isomaltodextrin oligosaccharides in 0.5∼7.5 $\mu\textrm{g}$ of each sample loaded. Interestingly, F values were equal for the same molecular weight sugars, although the structures were different from each other. Using F value of each sugar, we could determine and compare the exact total sugar concentration of different molecular weight maltooligosaccharide and isomaltooligosaccharide. We also could determine if the unknown sugar was a reducing or non-reducing compound by using optimized TLC with microwave oven method.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.4
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• pp.464-469
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• 2007

This research was worked out to investigate fermentation and functional properties of Hahyangju. Hahyangju was brewed by traditional method and the changes in chemical component and microorganisms in wine mash were evaluated during brewing. In the course of the first mash brewing, the yeast cell number was the highest after 6 days fermentation, and contained 11% alcohol, 0.82% total acidity and 0.53% amino acidity The final product of Hahyangju contained 19.2% alcohol, 0.32% reducing sugar, 0.46% total acidity and 0.24% amino acidity. The major organic acid was lactic acid containing 680.04mg/100mL. The total phenolic compound contents and electron donating ability of Hahyangju were 263.16 ppm and 93.08%, respectively. Nitrate scavenging effect was measured at various PH (1.2, 3.0, 4.2, 6.0); the highest effect was at pH 1.2 as 90.26%. Angiotensin converting enzyme (ACE) inhibition activity and fibrinolytic activity of Hahyangju ware 87.5% and 19.1 unit, respectively.

• Journal of Life Science
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• v.19 no.9
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• pp.1271-1276
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• 2009

Unlike the traditional preparation method for Chungkukjang, we prepared Dua-Chungkukjang with soybean fermented at $40^{\circ}C$ after the soaking, germination and steaming process, and we studied the physico-chemical characteristics of Dua-Chungkukjang. Reducing sugar content in both traditional Chungkukjang and Dua-Chungkukjang increased sharply after 10 hr of fermentation, but it decreased slightly after that. Total nitrogen content in both traditional Chungkukjang and Dua-Chungkukjang increased slowly as fermentation took place. Total nitrogen content reached 3,500 mg% and 3,700 mg%, and soluble nitrogen compound reached 750 mg% and 1,800 mg% after 40 hr of fermentation, respectively. $\beta$-Glucosidase activity increased continuously as fermentation took place, and it reached 193, 223, 235 and 248 units in Dua-Chungkukjang while it reached 125, 178, 205 and 214 units in traditional Chungkukjang after 10 hr, 20 hr, 30 hr and 40 hr of fermentation. This means that $\beta$-Glucosidase activity in Dua-Chungkukjang was $1.2{\sim}1.5$ times higher than that in the control treatment, traditional Chungkukjang. Total isoflavone content was $101.44{\mu}g$/g and $365.92{\mu}g$/g for 10 hr of fermentation, and $225.98{\mu}g$/g and $441.37{\mu}g$/g for 40 hr in traditional Chungkukjang and Dua-Chungkukjang, respectively. Isoflavone content of Dua-Chungkukjang was 2-3.5 times higher than that of traditional Chungkukjang. Anthocyanin content also increased continuously as fermentation took place, and it reached 5.0 mg/g and 6.9 mg/g in traditional Chungkukjang and Dua-Chungkukjang after 40 hr of fermentation, respectively.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.349-353
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• 1999

A study was carried out to see the effects of phenol on the biological degradation of a wastewater containing 2,4-dichlorophenol and 2,4-dinitrophenol and the biodegradation kinetic coefficients of Eckenfelder's modified model for the activated sludge process. The system containing base mix (BM) which was formulated with essential energy sources and nutrients was run down and washed out when 2,4-dichlorophenol and 2,4-dinitrophenol was introduced into the base mix unit without acclimation to phenol. Whereas for the system acclimated to phenol, the treatment efficiency was 91.9% in terms of $BOD_5$ and treatability for each chemical of phenol, 2,4-dichlorophenol, and 2,4-dinitrophenol was 99.8%, 43.3% and 62.5% based on concentration, respectively. Additional BM was added into the combined unit containing phenol, 2,4-dichlorophenol, 2,4-dinitrophenol so that the better treatment efficiency was achieved for each compound. The biokinetic coefficient of Eckenfelder's modified model without phenol acclimation was not estimated because the system did not reach the steady state. Thc coefficient for the phenol acclimation was 12.44 /day, however it was changed as 46.91 /day in addition of both of phenol acclimation and 47 mg/l of BM. The results presented above could be useful for the process design and further study in the field of biodegradation of benzene derivatives.