• Journal of Life Science
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• v.31 no.3
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• pp.330-337
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• 2021

This study was conducted to investigate the potential of Stewartia koreana as oral healthcare materials. The antibacterial activity of ethanol extracts from leaves and branches of S. koreana against oral bacteria was confirmed. The leaf and branch extracts (1 mg/disc) showed antibacterial activity against P. gingivalis only among several tested oral bacteria. The leaf extracts showed higher antibacterial activity, with values similar to those of chlorhexidine, which was used as a positive control. The MIC of the leaf extract against P. gingivalis was 0.4 mg/ml and showed bacteriostatic action. The inhibitory effects of the extract on biofilm formation and on gene expression related to biofilm formation by P. gingivalis were determined by biofilm biomass staining, scanning electron microscopy (SEM), and qRT-PCR analysis. The biofilm production rate and cell growth of P. gingivalis in the cultures treated with 0.2-2.0 mg/ml of S. koreana leaf extracts were significantly decreased in a concentration-dependent manner. The inhibitory effect on the formation of P. gingivalis biofilms at concentrations of 1 mg/ml was confirmed by SEM. The qRT-PCR analysis showed concentration-dependent suppression of the fimA and fimB gene expression associated with fimbriae formation in the cultures treated with 0.2-2.0 mg/ml S. koreana leaf extract. These results support the conclusion that S. koreana leaf extracts can be used as oral healthcare materials derived from natural materials, as demonstrated by the antibacterial action and inhibition of biofilm formation of P. gingivalis.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.4
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• pp.330-336
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• 2022

It is likely that the heading would occur early when air temperature increases. In 2022, however, the heading date was delayed unusually, e.g., by 3 to 5 days although temperature during the vegetative growth stage was higher than normal years. The objective of this study was to identify the cause of such event analyzing weather variables including average temperature, sunshine hours, and day-length for each growth stage. The observation data were collected for medium-late maturing varieties, which has been grown at crop yield experiment sites including Daegu, Andong, and Yesan. The difference in heading date was compared between growing seasons in 2021 and 2022 because crop management options, e.g., the cultivars and cultivation methods, were identical at those sites during the study period. It appeared that the heading date was delayed due to the difference in temperature responsiveness under a given day-length condition The effect of the temperature increase on the heading date differed between the periods during which when the day-length was more than 14.3 hours before and after the summer-solstice.. The effect of the temperature decrease during the period from which the day-length decreased to less than 14.3 hours to the heading date was relatively greater. This merits further studies to examine the response of rice to the temperature change under different day-length and sunshine duration in terms of heading.

• Journal of agriculture & life science
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• v.44 no.2
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• pp.7-15
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• 2010

This study was conducted to investigate the bacteriological and physiological quality of seawater and surface sediments in Sacheon Bay of Korea from January to September in 2009. During the study period, the means of temperature was range from 5.3 to $24.9^{\circ}C$ (mean $17.7{\pm}0.4^{\circ}C$), transparency range from 1.4 to 2.5 m (mean $1.8{\pm}0.5m$), suspended solid ranged from 16.2 to 35.8 mg/L (mean $24.2{\pm}2.2mg/L$), chemical oxygen demand ranged from 1.42 to $3.29mgO_2/L$ (mean $2.06{\pm}0.55mgO_2/L$), dissolved oxygen ranged from 6.7 to 9.5mg/L (mean $7.9{\pm}0.6mg/L$), respectively. Seafood, if eaten raw, carries the risk of food poisoning. Seafood poisoning is often cause by pathogenic microorganism originating from fecal contamination, such as Salmonella sp., Shigella sp. and norovirus. Fecal coliforms are an important indicator of fecal contamination. Therefor, data on fecal coliform are very important for evaluating the safety of fisheries in coastal areas. So, we investigated the sanitary indicate bacteria. In this study, 56 sea water samples were collected from the Sacheon Bay, and total and fecal coliforms were compared and analyzed. The coliform group and fecal coliform MPN's of sea water in Sacehon Bay were ranged from <1.8~7,900 MPN/100mL (GM 214.7 MPN/100mL) and <1.8~330 MPN/100mL (GM 9.7 MPN/ 100mL), respectively. Total coliforms were detected in 75.0% of the samples and 76.2% of the total coliforms were fecal coliforms. During the study period, the means of water content, ignition loss, COD, and acid volatile sulfates in sediments in Sacheon Bay were $53.28{\pm}2.58%$, $9.38{\pm}0.42%$, $14.23{\pm}3.36mgO_2/g$, $0.09{\pm}0.07mgS/g$, respectively.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.678-688
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• 2021

This study was conducted to provide growth characteristics and stand information in preparation for natural regeneration method and silvicultural treatment of seed tree method in Korean red pine stands by using the field inventoried data 18 years after the seed tree regeneration method in 2001 and analyzing the stand and sapling characteristics. The study area was located in the Research Forest of Kangwon National University, Chuncheon-si, Gangwon-do. In November 2018, we collected tree measurement factors, such as diameter at breast height (DBH), height, crown class, stem quality, tree age, and annual height increment on the established plots. We calculated the basal area, volume, height-diameter ratio (HD ratio), and additional stand density variables such as the relative density and %stocking to analyze the managed stands. The number of mother trees was 58 trees/ha, with a 17.7% stocking level, whereas the number of saplings was 2,330 trees/ha, with a 79.0% stocking level. In germination, the age distribution of saplings ranged from 2001 to 2007, with most belonging to 15-16 years. The development condition of saplings was 10 cm in DBH and 8 m in height. DBH and height were higher as the crown class is more dominant, and this difference was statistically significant in the analysis of variance and Duncan's multiple comparison test (p<0.0001). HD ratio ranged mostly between 80% and 90%, and more than 95% of sapling stems were of high quality, with a straight, unbroken top, non-sweep, and non-diseased stem. On average, the annual height increment of saplings was 21.9 cm at 1 year, 43.3 cm at 5 years, 54.3 cm at 10 years, and 64.3 cm at 15 years. The overall height growth with age increased smoothly. According to the analysis of covariance, the annual height growth by crown class differed significantly. The regression analysis parameters revealed that annual height growth increased with age and dominant crown class.

• Korean Journal of Breeding Science
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• v.50 no.4
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• pp.424-433
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• 2018

Watermelon (Citrullus lanatus) is an economically important vegetable crop all over the world, which has functional compounds such as lycopene and citrulline. Gummy stem blight caused by Didymella bryoniae is one of the most devastative diseases in watermelon. Single nucleotide polymorphisms (SNPs), which are genetic variations occurring between individuals with respect to a single base, were often used to construct genetic linkage maps and develop molecular markers linked to a variety of horticultural traits and resistance to several diseases. In this study, we developed high-resolution melting (HRM) markers based on SNPs generated from NGS resequencing of two parents in watermelon. Plant materials were C. lanatus '920533' (female and susceptible parent), C. amarus 'PI 189225' (male and resistant parent), and their $F_1$ and $F_2$ progenies. A total of 13.6 Gbp ('920533') and 13.1 Gbp ('PI 189225') of genomic sequences were obtained using NGS analysis. A total of 6.09 million SNPs between '920533' and 'PI 189225' were detected, and 354,860 SNPs were identified as potential HRM primer sets. From these, a total of 330 primer sets for HRM analysis were designed. As a result, a total of 61 HRM markers that have polymorphic melting curves were developed. These HRM markers can be used for the construction of SNP-based linkage maps and for the analysis of quantitative trait loci (QTLs) related to gummy stem blight resistance.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.489-496
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• 1997

This study was carried out to develop and investigate integrated mechanization system on polyethylene(P.E.) film mulching culture in sesame. Field trials were carried out to develop optimum mechanics for each step of manual operation in sesame culture and demonstrated those developed mechanics of sesame dibbling vinyl mulcher, sesame binder, sesame thresher and sesame grader at the farmer, s field of Hwasong (Kyunggi-do) in 1994 and 1995. Newly developed sesame dibbling vinyl mulcher brought saving manpower 280 hrs /ha for sowing and P.E. film mulching with it's 98％ of labour saving for the harvesting operation of sesame. Sesame Binder showed 93％ labour saving for cutting and binding with only 22 hrs /ha compared to 330 hrs /ha that of conventional. Sesame thresher was appeared to have 85％ effects of labour saving for threshing with completely dry sesame bundles at one time by 23 hrs /ha compared to 151 hrs /ha that of conventional. Sesame grader was appeared to have 72％ effects for sesame grain grading with 12 hrs /ha compared to that of conventional 54 hrs /ha. Grain yield of integrated mechanization culture system showed 6％ higher than that of coventional. Integrated mechanization culture system (sesame dibbling vinyl mulcher ＋ sesame binder ＋ sesame thresher ＋ sasame grader) showed 62％ of labour saving effects through whole steps of sesame culture by 472 hrs /ha compared to that of conventional 1, 230 hrs /ha.

• Korean Journal of Breeding Science
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• v.50 no.4
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• pp.478-484
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• 2018

A soybean cultivar "Chamol" for double cropping for use as soy-paste and tofu was developed using a pedigree method in 2011 as a cross between "Shinpaldal2" and "Keunol." A promising line, SS99502-2B-89-1-3-4-1-1, was selected and designated as "Milyang210". It was promising and showed good results from regional yield trials (RYTs) for 3 years from 2009 to 2011 and released with the name "Chamol." It has a determinate growth habit, white flowers, gray pubescence, yellow seed coat, yellow hilum, spherical seed shape, and large seeds (27.7 g per 100 seeds). The maturity date of "Chamol" was September 18 (100 day growing period) in RYT and it is suitable for double cropping with winter crops such as onion. "Chamol" was resistant to bacterial pustule and soybean mosaic virus and tolerant to lodging in fields. Furthermore, the average yield of "Chamol" was 2.51 ton/ha in the regional yield trials conducted for 3 years from 2009 to 2011.

• Journal of Aquaculture
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• v.21 no.4
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• pp.325-330
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• 2008

Two different Eelwardsiella tarda isolates, KFE and Edk-2, were obtained from Korea and Japan respectively. On the base of the previous results showing higher pathogenicity of E. tarda KFE compared to that of E. tarda Edk-2 isolate, we tried to determine the differences of antigenicities of these two isolates in loach which is one of the important species in freshwater aquaculture in Korea. Concentration of specific antibody in the serum appeared to be much higher in loach immunized with FKC of E. tarda Edk-2 than those found in loach immunized with FKC of E. tarda KFE. Cross-reaction analysis using agglutination test with normal and antigen-absorbed antisera implied the differences epitopes in the antigens of these E. tarda isolates. For the comparison of bactericidal activity of the produced antibody with different antigens, absorption analysis was performed and confirmed the presence of critical epitopes in the FKC of E. tarda KFE strain. The prophylactic agent, polysaccharide-bound protein (PS-K) injected 1 week before the artificial infection with E. tarda KFE isolates decreased the cumulative mortality in loach and would be on effective method to prevent the occurrence of bacterial infection including E. tarda.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.321-330
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• 2011

We experimentally investigated the effect of applied DC electric fields on the flame spread over polyethylene-coated electrical wire. The flame-spread rates over electrical wire with negative and positive DC electric fields from 0 to ${\pm}7$ kV were measured and analyzed. We compared the results for DC electric fields with previous results for AC electric fields. We explored whether or not various flame shapes could be obtained with DC electric fields and the main reason for the flame-spread acceleration, particularly at the end of the electrical wire, for AC electric fields. We found that DC electric fields do not significantly affect the flame-spread rates. However, the flame shape is mildly altered by the ionic wind effect even for DC electric fields. The flame-spread rate is relevant to the flame shape and the slanted direction in spite of the mild impact. A possible explanation for the flame spread is given by a thermal-balance mechanism and fuel-vapor jet.

• Journal of Environmental Impact Assessment
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• v.26 no.5
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• pp.315-330
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• 2017

The aim of this study is to examine the damage of plants in the islands due to the habitat and feeding of European rabbit (Oryctolagus cuniculus) and to suggest future management plan. The survey area Beomseom Island is found to be a vegetation distribution type that was formed secondary by the exposure of artificial interference except for evergreen vegetation distribution and European rabbit showed high habitat track density mainly in the lumbering area. Kkamakseom Island was identified as a severe vegetation distribution area due to interference, and European rabbit showed high habitat track density around deciduous broad leaved forests. Feeding plants of European rabbit was identified as a total of 12 families 17 breeds. Total 9 families 11 breeds were found in Beomseom Island while 5 families 6 breeds were found in Kkamakseom where most available food resources were loss to European rabbit. As for vegetation index of Beomseom Island, about 6.6% of total island area was declined and the vegetation index of Kkamakseom Island was reduced at most area of the island. In Kkamakseom Island, the area where EVI decreased to less than -0.008 unit/yr was reduced to 5.2%, and the area where it was reduced to -0.008 to -0.006 unit/yr in total was 13.32% of the total area. Thus, it was estimated to be seriously damaged by vegetation. Therefore, immediate management is required.