• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.344-352
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• 2019

Drought stress caused by global climate change is a serious problem for rice cultivation. Increasingly frequent abnormal weather occurrences could include severe drought, which could cause water stress to rice during the seedling stage. This experiment was conducted to clarify the effects of drought during the seedling period on yield and quality of rice. Drought conditions were created in a rain shelter house facility. The drought treatment was conducted at 3, 10, and 20 days after transplanting. Soil water content was measured by a soil moisture sensor during the whole growth stage. In this study, we have chosen 3 rice cultivars which are widely cultivated in Korea: 'Haedamssal' (Early maturing), 'Samkwang' (Medium maturing), and 'Saenuri' (Mid-late maturing). The decrease in yield due to drought treatment was most severe 3 days after transplanting because of the decrease in the number of effective tillers. The decrease in grain quality due to drought treatment was also most severe 3 days after transplanting because of the increased protein content and hardness of the grains. The cultivar 'Haedamssal' was the most severely damaged by water stress, resulting in about a 30% yield loss. Drought conditions diminished the early vigorous growth period and days to heading in early-maturing cultivars. The results show that drought stress affects yield components immediately after transplanting, which is a decisive factor in reducing yield and grain quality. This study can be used as basic data to calculate damage compensation for drought damage on actual rice farms.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.336-343
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• 2019

Wet direct-seeding (WDS) is an important method for improving the competitiveness of rice production in South Korea. We analyzed the optimum direct-seeding date to establish the rice standing rate in each area and selected suitable areas for WHS by considering the heading stage limit date for improving cultivation safety. As a result, the rice direct-seeding date to control weedy rice was around 5.15, 5.17-5.19, and after 5.20 in southern Youngnam, southern Honam, and the Middle Coast areas, respectively. However, the optimum seeding date for good standing rice was in late March in most areas. Analyzing by area, most of the southern plains and parts of the central inland plain are suitable for WHS. However, most parts of Gwangwon-do, and the northern parts of Chungbuk, Gyeongbuk, and Yeonghonam areas are not suitable for WHS, and should therefore avoid WHS.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.441-451
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• 2019

This study was conducted to investigate the crop characteristics of 181 sweetpotato germplasms collected from Korea and overseas. The longest shoot vine length was observed in IT232211 (354.8 cm) and the shortest shoot vine length was observed in IT232185 (32 cm). The maximum numbers of shoot branches and nodes were produced by IT232091 (23.0) and IT232174 (67.8), respectively. Differences in Rapid Visco Analyser profiles were observed for pasting parameters such peak, trough, final, breakdown, and setback viscosities; and pasting temperature. The peak and breakdown viscosities were highest in IT232050 and IT232010, at 338.3 and 207.2 Rapid Visco Unit (RVU), respectively. The trough viscosity was lowest in IT232019 at 103.8 RVU. IT232101 had the highest final viscosity (284.6 RVU), and IT232192 had the highest setback viscosity (81.7 RVU). IT232197 had the highest pasting temperature at 86.8℃, and that of IT232134 was lowest at 72.7℃. To evaluate functional substance content, we analyzed 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and total polyphenol content. The highest frequency proportion of starch was in the 10%-15% range (50.8% of the plants), followed by the 5%-10% range (38.1% of the germplasms). Sugar content ranged from 13.5 to 33.3% (23.2% on average); the highest frequency proportion of sugar was in the 20%-25% range (56.9% of the germplasms), followed by the 25%-30% range (25.4% of the germplasms). The highest frequency proportion of water was in the 70%-80% range (52.5% of the germplasms), followed by the 60%-70% range (44.2% of the germplasms). Our results provide basic data for the selection of useful resources and for the development of new sweetpotato varieties.

• Cartoon and Animation Studies
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• s.36
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• pp.437-467
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• 2014

This study is intended to reveal reading comic books helps improve creativity. Though the long-lasting negative recognition towards comic books has positively changed these days, we need a ground upon which the social recognition needs improvement in that children's comic books have been used as a learning tool. Its introduction points out that there has been shortage of empirical researches on comic book reading, and as one of the empirical research methods, presents a method of comparative analysis on comic book reading, school study, and creativity tests via survey. The theoretical background in the 2nd chapter, first, puts emphasis on the significance of the creativity theory among all the other theories related to creativity, which focuses on problem-solving capacity. Second, it theoretically reviews the meaning which 'fun' and 'interest' have in development of creativity in the context of developmental process of the modern educational theories. Third, it empathizes that traits of reading comic books start off with 'fun' and 'interest', that awareness of reality gets expanded via the process of characters making their way through a strange world with empathy and absorption, and that comic book reading has to do with creativity. Fourth, it presents a model questionnaire with which to study relationship between comic books and creativity in an empirical way. The analysis on the survey outcome in the 3rd chapter shows, first, that smart students read many comic books, not to mention that studying helps improve creativity, which indicates above all, comic book reading and improvement of creativity are not negatively related, but are mutually complementary. Second, that creativity enhanced by reading comic books is higher than that enhanced by studying, which may mean comic book reading is more effective than studying in developing creativity. It has drawn a conclusion based upon these results, that reading comic books bears positive efficacy on both studying and developing creativity. Standing on this conclusion, it proposes it necessary to develop methods by grades of educating how to read comic books and to provide a recommended list of comic books to read.

• Microbiology and Biotechnology Letters
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• v.40 no.1
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• pp.43-49
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• 2012

In this study, we investigated the antibacterial activity and stability of a cream containing Hippophae rhamnoides leaf extract. The MIC values of ethyl acetate fraction from an H. rhamnoides leaf on Escherichia coli, Pityrosporum ovale, Propionibacterium acnes and Staphylococcus aureus were 0.5%, 0.25%, 0.25% and 0.06%, respectively. Stability evaluations, pH, viscosity and absorbance of the cream containing 0.25% ethyl acetate fraction of H. rhamnoides, were performed. The cream was measured under 4 different temperature conditions under sunlight at 2-week intervals for 12 weeks. The viscosity and pH were measured by a comparison of the experimental cream with a similar control cream. The H. rhamnoides extract was found to have contributed to the stability of the emulsion product via a protective effect in maintaining the viscosity of the cream against sunlight. The absorbance variations of the experimental cream at 270 nm were, under sunlight; $45^{\circ}C$, $37^{\circ}C$, $25^{\circ}C$, and $4^{\circ}C$. In addition, any change in color or smell was not observed through the 12 weeks of the experimental period. These results indicated that the cream containing 0.25% ethyl acetate fraction of H. rhamnoides leaf extract was stable. Accordingly, this suggests that further study is needed to provide additional information for manufacturers, who are seeking the application of the extract to improve anti-oxidant and antibacterial activities and the stability of cosmetic products.

• Microbiology and Biotechnology Letters
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• v.40 no.1
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• pp.57-65
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• 2012

Antifungal compounds from Bacillus polyfermenticus CJ6 were purified using SPE, preparative HPLC, and reverse phase-HPLC. Antifungal compounds from B. polyfermenticus CJ6 were separated into three fractions (8, B, C) using preparative HPLC. LC/MS analysis of antifungal peaks suggested that B. polyfermenticus CJ6 produces lipopeptides; two kinds of iturin A ($C_{14}$, $C_{15}$), three kinds of surfactins ($C_{13}$, $C_{14}$, $C_{15}$), four kinds of fengycin A ($C_{14}$, $C_{15}$, $C_{16}$, $C_{17}$) and two kinds fengycin B ($C_{16}$, $C_{17}$). The antifungal activity of fraction 8, which was presumed as inturin A, was found to be stable after the pH, heat or proteolytic enzyme treatment, but it was unstable at 50-$70^{\circ}C$ for 24 hr. The antifungal activity of fraction B, which presumed as surfactins and fengycin A, was found to be stable after the heat treatment, but it was unstable in the pH 3.0 and after the protease (type I) or ${\alpha}$-chymotrypsin treatment. The antifungal activity of fraction C, which was presumed as fengycin A and B, was found to be stable in the pH 3.0-9.0 range and the heat treatment, but it was unstable with the treatment of protease (type I). The amino acid composition of the purified peaks 8-1 and 8-2 were Asx, Tyr, Gln, Pro, and Ser in a molar ratio of 3:1:1:1:1, which showed the same amino acid composition as iturin. From these results, we confirmed that antifungal compounds from B. polyfermenticus CJ6 most likely belonged to iturin A as well as surfactins and fengycins. As lipopeptides are known to act in a synergistic manner, the antifungal compounds from B. polyfermenticus CJ6 might have potential uses in biotechnology and biopharmaceutical applications.

• Microbiology and Biotechnology Letters
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• v.42 no.1
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• pp.73-81
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• 2014

Salsola collina, also known as Russian thistle, is widely distributed in and around waste facilities, roadsides, and drought and semi-drought areas, and is used as a traditional folk remedy in Chinese medicine for the treatment of hypertension. In this study, we have evaluated the anti-oxidative and anti-cancer activities of the ethanol extract of S. collina Pall. (EESC), and the molecular mechanisms of its anti-cancer effects on human colon carcinoma HT29 cells. EESC exhibited anti-oxidative activity through DPPH radical scavenging capacity and showed cytotoxic activity in a dose-dependent manner in HT29 cells. After EESC treatment, HT29 cells altered their morphology, becoming smaller and irregular in shape. EESC also induced cell accumulation in the G2/M phase in a dose-dependent manner, accompanied by a decrease of cell population in the G1 phase. The G2/M arrest by EESC was associated with the increased expression of cyclin-dependent kinase (CDK) inhibitor p21 and Wee1 kinase, which phosphorylates, or inactivates, Cdc2. EESC treatment induced the phosphorylation of Cdc2 and Cdc25C, and inhibited cyclin A and Cdc25C protein expression. In addition, S arrest was induced by the highest concentration of EESC treatment, associated with a decrease of cyclin A and Cdk2 expression. These findings suggest that EESC may possess remarkable anti-oxidative activity and exert an anti-cancer effect in HT29 cells by cell cycle regulation.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1159-1170
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• 2000

It is necessary to improve the ambient air quality through the proper treatment and control of pollutants by designating air pollutants to regulatory ones. Especially, human took a concern for particulate matters which raised visibility reduction, public health effects and injury of property for urban areas. In order to reduce the effect of particulate matters, we need to establish proper control strategies based on the concentration characteristics of particulate matters. In this study. to evaluate the characteristics of $PM_{2.5}$ and $PM_{10}$. thirty-eight samples of $PM_{2.5}$ and $PM_{10}$ were collected at Nam-Gu sampling site where continuous air monitoring system has been operated, from May, 1999 to November, 1999, and their concentrations for the mass and anion components($Cl^-$, $NO_3{^-}$, $SO_4{^{2-}}$) were analyzed. The important conclusions obtained in this study were as followings. Total average mass concentrations of $PM_{2.5}$ and $PM_{10}$ were 35.016 and $50.293{\mu}g/m^3$ respectively. and $PM_{2.5}/PM_{10}$ ratio was calculated 0.692. Total average concentrations of anion components in $PM_{2.5}$ were $1.581(Cl^-)$, $3.690(NO_3{^-})$ and $12.825(SO_4{^{2-}}){\mu}g/m^3$ and those in $PM_{10}$ were $2.471(Cl^-)$, $5.819(NO_3{^-})$ and $14.414(SO_4{^{2-}}){\mu}g/m^3$ respectively. From the correlations analysis. the correlation coefficient between mass concentration of $PM_{2.5}$ and $PM_{10}$ was calculated as 0.945. The correlation coefficients between $PM_{2.5}$ and anion components were analyzed as $Cl^-$(0.025), $NO_3{^-}$(0.788) and $SO_4{^{2-}}$(0.500) respectively, and the correlation coefficients between $PM_{10}$ and anion components were analyzed as $Cl^-$(-0.019), $NO_3{^-}$(0.806) and $SO_4{^{2-}}$)(0.535) respectively.

• Microbiology and Biotechnology Letters
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• v.48 no.2
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• pp.205-214
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• 2020

Cyanobacteria are microorganisms which have important roles in the nitrogen cycle due to their ability to fix nitrogen in water and soil ecosystems. They also produce valuable materials that may be used in various industries. However, some species of cyanobacteria may limit the use of water resources by causing harmful algal blooms in water ecosystems. Many culture collection depositories provide cyanobacterial strains for research, but their systematic preservation is not well-developed in Korea. In this study, we developed a method for the cryopreservation of the cyanobacteria Trichormus variabilis (syn. Anabaena variabilis), using alginate microcapsules. Two approaches were used for the experiments and their outputs were compared. One of the methods involved the cryopreservation of cells using only a cryoprotectant and the other used the cryoprotectant within microcapsules. After cryopreservation for 35 days, cells preserved with both methods were successfully regenerated from the initial 1.0 × 10⁵ cells/ml to a final concentration of 6.7 × 10⁶ cells/ml and 1.1 × 10⁷ cells/ml. Irregular T. variabilis shapes were found after 14 days of regeneration. T. variabilis internal structures were observed by transmission electron microscopy (TEM), revealing that lipid droplets were reduced after cryopreservation. The expression of the mreB gene, known to be related to cell morphology, was downregulated (54.7%) after cryopreservation. Cryopreservation using cryoprotectant alone or with microcapsules is expected to be applicable to other filamentous cyanobacteria in the future.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.39-46
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• 2011

NO oxidation is an important prerequisite step to assist the selective catalytic reduction (SCR) at low temperatures ($<200^{\circ}C$). Therefore, we conducted the lab- and bench-scales experiments appling the sodium chlorite powder ($NaClO_2(s)$) for the oxidation of NO to $NO_2$ and the carbon-based catalyst for the reduction of $NO_x$ and $SO_2$; the lab- and bench-scales experiments were conducted in laboratory and iron-ore sintering plant, respectively. In the lab-scale experiment, known concentrations of $NO_x$ (200 ppm), $SO_2$ (75 ppm), $H_2O$ (10%) and $NH_3$ (400 ppm) in 2.6 L/min were introduced into a packed-bed reactor containing $NaClO_2(s)$, then gases produced by the reaction with $NaClO_2(s)$ were fed into the carbon-based catalyst (space velocity = $2,000hr^{-1}$) at $130^{\circ}C$. In the bench-scale experiment, flue gases of $50Nm^3/hr$ containing 120 ppm NO and 150 ppm $SO_2$ were taken out from the duct of iron-ore sintering plant, then introduced into the flow reactor; $NaClO_2(s)$ were injected into the flow reactor using a screw feeder. Gases produced by the reaction with $NaClO_2(s)$ were introduced into the carbon-based catalyst (space velocity = $1,000hr^{-1}$). Results have shown that, in both lab- and bench-scales experiments, NO was oxidized to $NO_2$ by $NaClO_2(s)$. In addition, above 90% of $NO_x$ and $SO_2$ removal were obtained at the carbon-based catalyst. These results lead us to suggest that the combination of $NaClO_2(s)$ with the carbon-based catalyst has the potential to achieve the simultaneous removal of $NO_x$ and $SO_2$ at low temperature ($<200^{\circ}C$).