• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.251-259
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• 2016

This study examined the DO concentration distribution and ORP distribution using microbubbles on pilot-scale aeration tanks. As a result of MLSS mixing and oxygen transfer phenomenon using microbubbles, different DO concentrations were observed depending on the circulation of the liquid with the microbubble supply location on the lateral of an aeration tank. The simulation results of CFD (computational fluid dynamics) program showed that MLSS mixed with a microbubble supply in the middle the reactor is much better than on the left side of the reactor. A single reactor containing an anaerobic, anoxic, and aerobic zone, was evaluated without partition according to the location of the microbubble supply based on the experiments and CFD analysis. MLSS was separated into solid-liquid by the microbubble supply in the aeration tank. Consequently, selecting the appropriate microbubble size is important for MLSS mixing and was maintained at the proper DO concentration for biological treatment.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.203-206
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• 2007

부유녹조와 갯버들 및 부레옥잠이 수질에 미치는 영향을 탐구하기 위해 5월 초에서 6월 말까지 실험실 수조의 수질변화를 고찰하면서 얻은 결과는 다음과 같았다. 부영양화가 진행되는 물에 수변식물인 갯버들과 수생부엽식물인 부레옥잠은 상호 혹은 단독으로 작용하여 DO, pH, SS, 탁도, 입자수 농도, Chl a 농도를 어느 시점에서 큰 폭으로 감소시켰고 갯버들과 부레옥잠의 상호작용시 그 효과가 가장 크게 나타났다. 부유녹조 단독으로는 DO와 pH 등을 서서히 감소시켰다. 이 결과로부터 갯버들 및 부레옥잠은 부유녹조와 경쟁관계가 되어 수질개선에 상당한 영향을 미칠 수 있는 것으로 추정된다.

• Korean Journal of Remote Sensing
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• v.31 no.6
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• pp.549-560
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• 2015

With the global scale impact of atmospheric $CO_2$ in global warming and climate system, it is necessary to monitor the $CO_2$ concentration continuously on a global scale, where satellite remote sensing has played a significant role recently. In this study, global monthly $CO_2$ concentrations obtained by satellite remote sensing were compared with ground-based measurements at Anmyeon-do and Gosan Korean Global Atmosphere Watch Center. Atmospheric $CO_2$ concentration has increased from 371.87 ppm in January 1999 to 405.50 ppm in December 2013 at Anmyeon-do station (KMA, 2013). Comparison of the continuous measurements by flask air sampling at Anmyeon-do shows the same trend and seasonal variations with those of global monthly mean dataset. Nevertheless, the trends of $CO_2$ over Northeast Asia showed the higher than those of global and the trends also changes with different slope. $CO_2$ products derived from Greenhouse Gases Observing Satellite (GOSAT) and Atmospheric Infrared Sounder (AIRS) were compared with ground-based measurement at Anmyeon-do. The monthly mean values of GOSAT and AIRS data are systemically lower than those obtained at Anmyeon-do, however, the seasonal cycle of satellite products present the similar trend with values of global and Anmyeon-do. The accuracy of $CO_2$ products from GOSAT and AIRS were evaluated statistically for two years from January 2011 to December 2012. GOSAT showed good correlation with the correlation coefficient, RMSD and bias of 0.947, 5.610 and -5.280 to ground-based measurements respectively, while AIRS showed reasonable comparison with 0.737, 8.574 and -7.316 at Anmyeon-do station, respectively.

• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.195-202
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• 2012

Three-season field study was conducted to investigate the distribution of monoterpene(10) and air anion in ambient air at five forests. ${\alpha}$-Pinene, camphene, sabinene, ${\beta}$-pinene, myrcene, terpinolene, limonene, 1,8-cineol, linalool, and camphor were quantified in the samples collected. The highest 4-hour mean concentration of total monoterpene were ${\beta}$-pinene+myrcene as 958 pptv at Juknokwon dominated by bamboo and ${\alpha}$-pinene (524 pptv), limonene (445 pptv) at Wood Land and Suncheon Bay, respectively. The seasonal means were observed to peak during spring with their maximum at Wood Land and Seonam Temple and during summer at Juknokwon and Suncheon Bay. The 24 hour concentration mean of atmosphere standards were found with much lower values than those by law. The highest concentrations of air anion were measured $400{\sim}3,000ea{\cdot}mL^{-1}$ through the sites. There is no significant correlation between the concentration of monoterpene and air anion.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.327-332
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• 2002

식물조직배양용 바이오리액터내 배양액의 pH, DO 농도를 on-line으로 계측하고 제어하기 위한 시스템을 개발하여 시스템의 성능시험과 경시간격별 배양액의 농도변화를 계측하였으며, 주요 연구결과는 다음과 같다. 가. 복수의 바이오리액터내 배양액의 pH, DO 농도를 전극을 이용하여 on-line으로 계측하며, 농도의 계측값과 목표값을 비교하여 피드백으로 제어할 수 있는 시스템을 개발하였다. 나. 배양액의 농도변화를 계측한 결과 pH는 배양초기 5.0에서 배양이 경과됨에 따라 서서히 떨어져 2개월 후에는 3.8까지 떨어지는 것으로 나타났다. 다. 배양액의 성분중 배양초기에는 암모니아태 질소의 흡수가 질산태 질소보다 많이 이루어져 구근으로부터 H+이온을 유출시킴으로 pH의 값이 떨어지는 것으로 나타났다. 라 오염이 발생한 리액터내의 배양액 성분은 pH의 값이 3이하로 떨어졌으며, 이로부터 배양액의 오염경보를 할 수 있는 것으로 나타났다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.62 no.4
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• pp.2-7
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• 2020

• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.38-44
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• 2013

To construct the system controlling the aeration volume for D wastewater treatment plant effectively, the fluctuation of aeration volume was analyzed with changes of factors of the influent. As a result, the range of aeration volume was wide to maintain the certain concentration of DO, and the key factor to decide the aeration volume was found to be the temperature, F/M ratio, the loading rate of $BOD_5$ and T-N of the influent. Among the factors, the temperature of the influent had the most decisive effect on the aeration volume. The result showed that $45.8m^3/h$ of the aeration volume was needed with an increase of $1^{\circ}C$ of the influent, and the effect of the season was considered. Since the temperature of the influent is affected by a change of season, same as F/M ratio, the loading rate of the influent and the concentration of MLSS, it seemed that the change of the temperature of the influent affects the aeration volume even more. Therefore, it is preferable to consider the loading rate of the influent and F/M ratio altogether, rather than considering only one factor when deciding aeration volume.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.166-166
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• 2021

국내·외 유해화학물질 유출로 인한 하천오염사례가 많이 일어나고 있다. 이때 수질의 농도측정은 직접 도섭으로 하천의 정보 대한 정보를 취득하기 어렵기 때문에 간접적인 방법으로의 정보취득이 중요시 되어야 한다. 그에 따른 방법으로 주입식의 표면부자를 활용한 방법 이용한 수질농도 측정방법 등이 있다. 하지만 이런 농도추정은 이동확산으로 인한 변위가 커지게 되어 시간간격 설정에 대한 어려움 등이 있고, 수질오염에 대한 추적이 가능할 수 있을지에 대한 분석연구가 필요하다. 따라서 이러한 수질농도의 대한 분석을 실시하여 고성능 GPS전자부자를 이용한 추적이 필요하다. Lab-Scale에서 GPS 전자부자를 이용하여 수질정보취득에 일반항목인 수온, PH, EC, DO을 측정함으로써 일반항목에 대한 상관관계와 그에 따른 관계곡선을 제시하고, 고성능 GPS 전자부자를 이용한 측정결과와 YSI를 이용한 측정결과를 비교분석하여 농도경향에 대한 추적으로 오염물질이나 유해화학물질의 정보전달을 통해 원인분석 및 예상경로를 파악할 수 있다. 또한 간접적인 측정을 통해 진행되고 실시간으로 정보를 취득할 수 있기 때문에 수질측정에 접근성 및 안정성 까지 확보할 수 있다. 더 나아가 홍수시 사용뿐만 아니라 기본에 사용되는 수질측정 방법의 한계점까지 보완할 수 있다. GPS 전자부자의 지속적인 연구는 향후 하천 측정 시스템에 많은 도움을 줄 것으로 사료된다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.6
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• pp.581-585
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• 1986

A growth experiment of the Israeli strain of common carp (Cyprinus carpio) under varying dissolved oxygen levels in the recirculating water system was conducted at the Fish Culture Experiment Station of the National Fisheries University of Pusan from August 28, 1985 to September 17, 1985. Five tanks with a capacity of $5m^3$ of water each were used under the same condition of water parameters except for dissolved oxygen levels which were designed to maintain at 2.0, 2.5, 3.0, 3.5 and 4.0 mg/l ranges. The weight of fish in the beginning was about 300g and each tank was stocked with 200kg of fish. DO level of 3.5mg/l was found to be the best level with a feed coefficient of 1.57 and a daily growth rate of $1.411\%$ whereas 4.mg/l showed a slightly decreased performance of 1.63 and $1.365\%$ respectively. The amounts of feed consumed in 3.5 and 4.0mg/l DO levels were almost the same. Below 3.0mg/l DO levels the growth rate markedly decreased. Furthermore, in 2.0 and 2.5 mg/l groups, the fish did not accept feed vigorously and after feeding the fish usually concentrated around the inflow point showing oxygen deficiency response, The experiment indicates that the DO range of 3.5 to 4.0mg/l is the optimum level for the best growth at $27.5^{\circ}C$. DO concentration above these levels is considered a waste of energy resulting in uneconomical performance, and on the other hand, below these levels, the carp certainly shows a poor growth performance.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.2
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• pp.220-228
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• 2007

In this study, effective simultaneous nitrification and denitrification reaction was accomplished in a completely mixed single bioreactor. As the important factors on the reaction, optimal DO concentration and effective range of influent C/N ratio was investigated with the synthetic wastewater. Experimental results show that stable nitrogen removals were accomplished with 0.5 mg/L DO concentration and over 7 C/N ratio. Nitrogen removal efficiency of the real municipal wastewater was low with 0.5 mg/L DO concentration because of its low C/N ratio. The increment of the C/N ratio at the inflow of the municipal wastewater with addition of external carbon source (glucose) over 7(up to 14) shows over 70% nitrogen removal in the single bioreactor.