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관상어 치어의 먹이원인 물벼룩 증식에 적합한 배양재료의 선정과 수질환경 특성
공병욱,김기범,김현진,송승현,서하나,박상진,정정조 한국환경기술학회 2020 한국환경기술학회지 Vol.21 No.2
The purpose of this study is to select the optimal culture materials for the growth of water flea and decide the adoption time of fry by understanding the change of dissolved oxygen in the water environment for ornamental fish culture in mud pond. From the result of determining the water quality according to the culture materials, pH was maintained in the range of 7.1 to 8.3 for all materials and conditions. In the case of fowl droppings, rice straw and fertilizer, the change of DO concentration was relatively small, but in the case of rice bran, fish food and yeast, the DO concentration tended to increase rapidly with time. The concentration of Chl-a was not changed significantly in fowl droppings and rice straw, but it increased rapidly after about 15 days in rice bran, fertilizer, fish food, and yeast. In the case of fowl droppings, the number of daphnia population increased from 5 days with the maximum after 15 days, and then remained stable. In the case of fertilizers, the population was less than 5 inds/10mL, which was the smallest. In the case of rice bran (0.6, 1.0, 3.0 g/L), fish food (0.3, 0.6, 1.0 g/L), and yeast (0.3, 0.6, 1.0 g/L), the number of daphnia increased rapidly after 15 days. There was a tendency that the number of individuals was about 2~3 times higher than that of fowl droppings. Rice straw and fertilizers were not suitable for the culture of water flea. Judging the criteria for the adoption time of the fry based from the DO (5 mg/L or more) and the number of daphnia (more than 5 inds/10mL), it seems appropriate to adopt the fish fry after 10 to 15 days from the fowl droppings addition. However, in the case of rice bran, fish food, and yeast, it is appropriate to adopt the fry about 25 days after addition.
공병욱,강성태,이연수,Gong, Byeong-Uk,Gang, Seong-Tae,Lee, Yeon-Su 재료연구소 2010 機械와 材料 Vol.22 No.2
석탄화력발전소의 효율향상은 스팀온도 및 압력의 증가를 통해 꾸준하게 이루어지고 있으며, 이러한 고효율의 화력발전은 사용 연료의 감소 뿐 아니라 $SO_x$, $NO_x$, $CO_2$ 등의 환경 가스배출을 감소시키는 효과도 있다. 이에 따라 운전조건을 고온, 고압화하려는 노력이 전 세계적으로 꾸준히 전개되고 있으며, 경제성 있고 높은 고온특성을 갖는 터빈 및 보일러 소재확보 여부가 발전소 건설 가능성을 결정하는 가장 주요한 요소 중 하나로 작용하고 있다. 본 고에서는 USC(Ultra Super Critical) 조건에 사용하기 위한 소재의 개발과정과 현대 사용되고 있는 다양한 발전용 고온소재의 특징에 대해 기술하고자 한다.
순천만 연안습지의 토양환경에 따른 염생식물의 분포 특성
공병욱,이원준,박명현,이우진,서하나,라덕관,정정조 한국환경기술학회 2019 한국환경기술학회지 Vol.20 No.1
The purpose of this study is to investigate the characteristics of soil environment of halophytes habitats and to provide information for restoration and management of halophytes in the Suncheon Bay. We investigated the characteristics of soil environment from August 2016. Specific conclusions derived from this study are as follows. Soil of Phragmites communis habitats was silty clay of muddy facies which are mixed with silt and clay. It was shown 54.8 % of water contents, 7.6 of pH, 15.8 psu of salinity and 28.8 mS/cm of electric conductivity. Organic matter, T-N and available phosphate of it were shown range of 5.8~9.8 %, 0.5~1.3 mg/g and 7.6~9.6 mg/kg, respectively. Habitats of Suaeda japonica was silty clay in common with Phragmites communis. It was shown 39.9 % of water contents, 7.2 of pH, and salinity and electric conductivity of it were relatively high as 18.1 psu and 33.7 mS/cm. Organic matter, T-N and available phosphate of it were shown range of 5.3~6.8 %, 0.6~0.8 mg/g and 7.7~8.5 mg/kg. Habitats of Scirpus planiculmis had similar environment of Phragmites communis, while Carex scabritolia was inhabited on sand of soil. Soil texture of non-vegetation was silty clay, and soil environment was shown similar condition to halophytes habitats in most items. But salinity and electric conductivity of it were highest as 26.9 psu and 48.4 mS/cm in surveyed area. The reason for it is that the influx of fresh water has an adverse environment and salt accumulation can be easily done due to the influence of seawater. For efficient management, restoration and conservation, improvement measures related to smooth circulation of fresh and sea water through topographic restoration will be needed.