• Journal of Korea Water Resources Association
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• v.35 no.2
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• pp.149-159
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• 2002

The monthly water quality data measured at 19 stations located in the Sapkyo reservoir watershed were clustered into 2 to 7 clusters and factor analysis was conducted to characterize the water quality, using the information obtained from cluster analysis. The result of cluster analysis shows that Sapkyo reservoir and each stream (Sapkyo stream, Muhan stream and Kokkyo stream) in Sapkyo reservoir watershed hove their own water quality characteristics. The result of water quality analysis indicates that the concentration of suspended solids from Sapkyo reservoir is much higher than those of other streams, and which is probably because of increment of phytoplankton biomass with rich nutrient flowing Into Sapkyo reservoir from the upper stream of watershed. Furthermore, the concentrations of biochemical oxygen demand and chemical oxygen demand were 3.5 to 4.8 times and 1.7 to 2.5 times those of other streams, respectively. The overall water quality of Sapkyo reservoir watershed was considered to exceed eutrophic condition. Based on factor analysis, the water quality characteristics of Sapkyo stream and Muhan stream were closely related with farm land and residence. The water quality of Kokkyo stream was influenced by superabundant organic matter flowing from Chonan city and district wastewater treatment plant located in the upper stream of Kokkyo stream. The water quality factor influencing Sapkyo reservoir was closely related with water quality factors of other three streams.

• Korean Journal of Agricultural Science
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• v.26 no.1
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• pp.77-83
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• 1999

The populations of microorganisms adhered on rice straws which had been ricked in the fields around Chungchong areas during the winter season from February to March in 1998 were investigated. The number of mesophilic bacteria including bacilli was generally high in the middle part of straw. And it appeared to be higher in the samples from rural areas than those from suburb. Thermophilic bacteria and actinomycetes were rarely to be detected in most samples. Coliform bacteria were detected in a few samples which collected from Kwanpyong-dong of Taejon-city, Jangpyong-meun and Jungsan-meun of Chongyang-koon, indicating that these areas were contaminated by sewage and livestock wastes. Following the fermentation of Chungkukgang employed the middle parts of straws from Mok-meun of Chongyang-koon as a source of microbial inoculum, qualities of the fermented products such as amino-nitrogen content, viscosity and protease activity, were examined: the application of rice straws resulted in better qualities of the fermented products when compared to the control, however the methods of application appeared to have little or no effect on the quality.

• Journal of Embryo Transfer
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• v.23 no.4
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• pp.257-261
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• 2008

The objective of present study was to investigate the effect of seasons on reproductive performance of Hanwoo and Holstein heifers. Heat stress in summer or cold stress in winter stress to Hanwoo and Holstein heifers may bring reproduction failure, which would pose an important economic loss, even around Daegwallyeong region located in high mountainous area. Seasonal differences in the serum levels of LH, FSH and progesterone ($P_4$) in response to environmental factors (hot and cold) out of 20 pubertal Hanwoo heifers in Daegwallyeong, Gangwon Province and 20 non-lactating Holstein heifers in Chonan city of Republic of Korea at 2-3 years of age were compared. Blood samples for hormonal analysis were from jugular vein after detection of estrus repeatedly over four seasons within four-week intervals (Spring: May to June, Summer: July to August, Autumn: October to November and Winter: January to February). In Hanwoo heifer population, averages of LH and FSH concentration in spring and in summer were greater compared to those in winter (p<0.05). LH or FSH levels tended to be greater (p=0.06) in spring and less (p=0.09) in winter compared to the levels in autumn. Only in summer, cattle seemed to show lower LH or FSH secretion (p<0.05). Similar to the results in Hanwoo heifers, the serum concentrations of LH and FSH in Holstein heifers decreased further by heat stress in summer when P 4 levels were high during luteal phase. The results demonstrate significant effect of summer heat on reproduction of Hanwoo or Holstein heifers. Although parameters indicating the extent of heat stress were not measured in this study, we suggest that serum hormone levels could be considered as successful indicators of summer heat stress condition for Hanwoo and Holstein heifers even under rather cool summer climate.