• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.162-175
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• 2000

The present study was carried out to clarify the distribution of rotifera with salinity variation during the period from February 1998 to July 1999. Rotifera consists of 27 genera and 88 species, from the maximum occurrence of 39 species in November, 1998 to the minimum of 21 species March, 1998. With 32 dominant species, Keratella cochlearis cochlearis, K. cochlearis f. tecta, Ascomorpha saltans saltans and Asplanchna (s. str.) priodonta priodonta occurred predominantly. Distribution of Rotifera related to salinity showed that 36 species occurred in the freshwater zone, 3 species in the mixo-oligohaline zone ($0.5{\sim}5.0%_o$) and mixo-mesohaline zone ($5.1{\sim}28.0%_o$) respectively, on the other hand 2 species (Asplanhna (s. str.) priodonta priodonta, Synchaeta oblonga) in all zones. Average abundance by salinity ranged from $1,273\;ind./m^3$ ($25.0{\sim}28.0%_o$ to $16,259\;ind./m^3$ ($15.1{\sim}20.0%_o$. The percentage composition calculated effect by stepwise multiple regression of the pearson correlation coefficient value of environmental factors and Rotifera abundance (station $1{\sim}4$) revealed that it was 74.32% in BOD, 72.15% in COD, 69.77% in conductivity, 65.87% in $Cl^-$ and 58.27% in chlorophyll a. Also, (Station $5{\sim}12$) revealed 9.11% in $Cl^-$, 7.67% in TP and 6.20% in chlorophyll a.

• Korean Journal of Ecology and Environment
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• v.50 no.4
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• pp.422-431
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• 2017

The biogeochemical information of riverine organic matter gives a detailed and integrated recording of natural and anthropogenic activity within a watershed. To investigate the changes in quality and quantity of organic carbon transporting from mountain to ocean via river channels, we estimated the concentrations of dissolved (DOC) and particulate organic carbon (POC), and then traced the source origin of POC using stable carbon isotopes ratio before and after summer rainfalls in the Tamjin River and Ganjin Bay, Korea. Along the small watershed, a total of 13 sites including headwaters, dam reservoir, river and estuary were established for the study. We found some interesting findings in the aspect of distribution of DOC/POC concentration changing their origin sources dynamically flowing downstream. In particular, the river channel transport downstream mainly DOC to river mouth, although upper dam reservoir increased POC concentration by phytoplankton production in summer. Whereas, in the river mouth and estuary, POC was dominated not only by local supply from nearby reed saltmarsh, but also by marine phytoplankton production, respectively. The findings can contribute to increasing the understanding of riverine organic carbon transport in upper large dam and lower open estuary system.

• Journal of Food Hygiene and Safety
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• v.12 no.1
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• pp.9-14
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• 1997

Vibrio mimicus is a closely related species with V. cholerae, and has been reported to be associated with gastrointestinal infections. Although extraintestinal infections of these vibrios have also been reported in Japan and Southeast Asia. But little research papers on V. mimicus was reported in Korea. Therefore, we tried to isolate V. mimicus from the environmental sea water from April to July in Pusan, Korea. Among the isolated strains, we selected the strongest hemolytic strain and then named V. mimicus SM-9. In this paper, we checked the antibiotic susceptibility and psychrotrophic characteristics of the isolated strain. Hemolytic activity of the hemolysin produced by the isolated strain was also measured. V. mimicus was not detected from the sea water samples in April and May, but its detection rate was relatively high in June and July in Pusan, Korea. The bacteriological characteristics of V. mimicus SM-9 were Gram-negative rods, motile, oxidase positive, Voges-Proskauer negative and sucrose negative. In 23 kinds of antibiotics susceptibility test, V. mimicus SM-9 showed susceptibility to the most of antibiotics submitted while it was resistive against lincomycin, oxacillin, rifampin and vancomycin. Hemolytic activity of the hemolysin produced by V. mimicus SM-9 was highest in stationary phase of the growth curve in BHI broth at 37$^{\circ}C$ and its activity was reached 18 HU per $m\ell$ of culture supernatant. For checking the psychrotrophic property of V. mimicus SM-9, the decreasing rate of the strain in phosphate buffer solution and yellowtail flesh homogenate was examined during the storage at 4, 0, -4 and -2$0^{\circ}C$. The decreasing rates of the selected strain stored in phosphate buffer solution were greater than those in fish homogenate. Decreasing rates of V. mimicus SM-9 stored in phosphate buffer solution were not significantly different by the storage temperatures. The viable cell counts of the strain were decreased as 5 log cycles after 120 hours at all the tested temperatures. While decreasing numbers of the strain in fish homogenates were 2*4 log cycles after 120 hours. The decreasing pattern of the strain numbers were very slow after 200 hours at all the stored temperatures.

• Research in Plant Disease
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• v.16 no.2
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• pp.109-114
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• 2010

The occurrence factors of Rice stripe virus (RSV) in Chungcheongbukdo were analyzed by investigating the viruliferous insect rate (VIR) of overwintered small brown plant hopper (SBPH), the population density of SBPH, the infection rate of natural host plants, and the occurrence rate of RSV on rice paddy fields at the 3 areas of Cheongwon, Jincheon, and Boeun in 2008 and 2009. The average VIR of overwintered SBPH was 0.0% in 2008 and 1.1% in 2009. From SBPH collected on early June in 2009, VIR was higher as 1.4% at Jincheon and 4.2% at Boeun than those of overwintered SBPH, and this higher VIR might relate stronlgy with the adult population of SBPH immigrated from China. The populations of SBPH at Cheongwon, Jincheon and Boeun in 2008 were 3.8, 7.5 and 20.8 Head/$m^2$, respectively. However, those of Cheongwon and Jincheon increased up to about two folds as 8.4 and 13.1 in 2009. No RSV was detected on the natural host plants including barley. The factors involved in RSV occurrence were affected negatively by the low VIR of overwintered SBPH, the low population of overwintered SBPH, the low infection rate of RSV on the natural host plants, and the clean cultivation environment in Chungcheongbukdo.

• Korean Journal of Organic Agriculture
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• v.21 no.3
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• pp.413-422
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• 2013

This experiment was conducted to clarify the effect of double layer mulching on reducing the labor required to weed control and Leaf sheath training of the garlic cultivation. Six mulching methods(non-mulching, transparent P.E., rice hull+transparent P.E., sawdust+transparent P.E., rice straw+transparent P.E., black P.E. film+ transparent P.E.) were used for the experiment, and transparent P.E film was removed on April 10. Weed occurrence was in the order of black P.E. film< transparent P.E

• Journal of Korea Water Resources Association
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• v.33 no.3
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• pp.299-306
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• 2000

Korea IS one of countries to be predicted short of water in the 21st century. The government has been investigating various alternatives to resolve the problems including construction of reservoirs. Freshwater retention techniques using boom and skirt system is one of them. It is very difficult to intake water in the estuaries of south and west coast of Korea because a big tide penetrates into an upstream river. Thus, means or retaining and keeping separate freshwater from seawater could potentially be helpful in solving the water supply problems. In this study, the proposed means to achieve freshwater retention is by use of floating boom and skirt systems. The hydraulic viability of these systems in taking advantage of natural stratification tendencies between the fresh and seawaters has been investigated through hydraulic experiments. It is found that freshwater retention capacity depends on skirt length and the opening beneath the skirt. The choice of skirt length IS very important to optimize freshwater storage because longer skirt lengths cause faster mixing and shorter lengths retain less volume. Results show that the freshwater retention volume generally increases as the length of the skirt increases. However, they show that water storage might be insufficient if skirts were either too long or too short.

• Journal of Wetlands Research
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• v.12 no.3
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• pp.129-144
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• 2010

We have studied the changes of the environmental and vegetational factors according to the hydro-seral stages in the shoreline of the lagoons, Korea. We have divided seral stages into 7 stages from open water stage to the stratified forest stage considering as the characteristics of water body, dominance of submerged and emergent plant, and development of the shrub, subtree and tree layer. According to the successional stage, water depth gradually decreased and water quality changed from seawater to brackish water and from brackish water to fresh water, organic matter in a soil layer gradually increased, and the litter layer grew up. As the development of the vegetation structure, the life-form of the vascular plants changed as follows; open water ${\rightarrow}$ submerged plant and floating-leaved plant ${\rightarrow}$ emergent plant and submerged plant ${\rightarrow}$ emergent plant ${\rightarrow}$ emergent plant, mesophyte and scrub ${\rightarrow}$ mesophyte. In the late seral stage, the 3 different forest types were established by the water retention or drainage and nutrient accumulation of the soil layer. Salix dominant forest developed in the wetted sites, the forest type dominated by Pinus thunbergii, Carex pumila and mesophytes developed in the well drained sites causing by sand substrate, and the forest type dominated by the planted or ruderals such as Pinus densiflora, Robinia psedo-acacia, Festuca ovina, Setaria viridis ect. developed in the sites composed of forest soil introduced by artificial reclamation.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.9 no.2
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• pp.147-152
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• 2006

Purpose: Efficacy of the new rotavirus vaccines ($Rotarix^{(R)}$, $RotaTeq^{(R)}$) recently developed can be affected by the rotavirus genotypes prevalent in communities. We performed this study to identify the recent distribution of rotavirus genotypes prevalent in Jeju. Methods: Genotyping of human rotaviruses was performed using 81 samples collected from 154 inpatients and outpatients with rotavirus gastroenteritis at Cheju National University Hospital between July 2005 and June 2006. All six (1, 2, 3, 4, 8, 9) G serotypes were identified by amplification of segments of the gene for VP7 using the reverse transcription-polymerase reaction (RT-PCR). Results: The results of RT-PCR for 81 samples were all positive. G typing of the VP7 protein showed that G1 was the most dominant circulating genotype (65.5%) followed by G2 (14.8%), G3 (13.6%), G8 (1.2%), G9 (1.2%), G4 (0%), and a combination of G1/G3 (3.7%). Conclusion: This distribution of rotavirus VP7 genotypes in Jeju is different from that in other domestic areas; the most dominant circulating genotype was G1.

• Journal of the Korean Vacuum Society
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• v.7 no.1
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• pp.51-58
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• 1998

ZnS and TB-doped ZnS (ZnS:Tb) thin films were grown by traveling wave reactor atomic layer epitaxy (AKE) and characterized using materials and surface analysis techniques. $ZnCl_2$, $H_2$S,and tris(2,26,6-tetramethyl-3,5-heptandionato) terbium ($Tb(TMHD)_3$) were used as the precursors in the growth of ZnS:Tb films. The dependence of Cl content in ZnS films on growth temperature was investigated using Rutherford backscattering spectrometry. The Cl content decreased from approximately 9 at.% to 1 at. % as increasing the growth temperature from 400 to $500^{\circ}C$. The segregation of Cl in near surface region was also observed by depth profiling using Auger electron spectroscopy. Scanning electron microscopic studies showed that the ALE-grown ZnS and ZnS:Tb film during ALE process using $Tb(TMHD)_3$was also investigated. Approximately 1 at.% of O in ZnS:Tb(0.5 at.%) film which showed a good crystallinity of hexagonal 2H structure.

• Journal of Animal Science and Technology
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• v.51 no.2
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• pp.129-134
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• 2009

The aim of this study was to estimate genetic parameters and annual trends on the racing performance of Thoroughbred horses by a statistical analysis of the resulting records. We used the racing results of 245,979 observations for 13,458 horses recorded in 19 years of race held at Seoul and Busan racing tracks, provided by Korea Racing Authority. After a careful adjustment of some variables such as racing times, jockey and trainer numbers and the average prize a horse won, we selected significant factors that explain the result of racing records of a horse by stepwise AIC and BIC methods. The estimated heritability and repeatability were 0.322 and 0.332, respectively. The average of annual phenotypic and genetic improvement was -0.166 seconds and -0.161 seconds, respectively. Based on the statistical approach, we established reasonable animal model of well-set variables, which is important in the study on estimating performance of racing horses.