• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.86-86
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• 2021

온천천은 부산광역시 금정구, 동래구, 연제구를 흐르는 도심 하천으로 부산 시민들의 도심 속 산책길, 자전거 길 등으로 활용되는 도시하천이다. 그러나 온천천 양안의 동래 곡저 평야가 시가지화 되고 온천천 발원지인 금정산 주변에서 무허가 상수도를 사용하고 각종 쓰레기와 하수의 유입으로 인해 하천 전체가 하수관으로 변해왔다. 이에 따라 부산광역시는 온천천 정비 계획을 시행하여 하천 정비와 함께 자동측정망을 설치하여 하천의 DO (dissolved oxygen), 탁도, TDS농도 등 자료를 수집하고 있다. 그러나 자동측정망으로 쌓여가는 데이터를 활용하여 DO농도 예측은 거의 이뤄지지 않고 있다. DO는 하천의 수질 오염 정도를 판단하는 수질인자로 역사적으로 하천 연구의 주요 연구 대상이 되어 왔다. 본 연구에서는 일 자료 뿐만 아니라 시 자료를 기반으로 RNN-LSTM 알고리즘을 활용한 DO예측을 시도하였다. RNN-LSTM은 시계열 학습에 뛰어난 알고리즘으로 인공신경망의 발전된 형태인 순환신경망이다. 연구에 앞서 부산광역시 보건환경정보 공개시스템으로부터 받은 자료 중에서 교정, 보수 중, 비사용, 장비전원단절 등으로 인해 누락데이터를 2014년 1월 1일부터 2018년 12월 31일의 데이터 전수조사 후 이상데이터를 확인하여 선형 보간하여 데이터를 사용하였다. 연구에서는 Google에서 개발한 딥러닝 오픈소스 라이브러리인 텐서플로우를 활용하여 부산광역시 금정구 부곡동에 위치한 부곡교 관측소의 DO농도를 시간 또는 일 예측을 하였다. 일 예측 학습에는 2014년~ 2018년의 기상자료(기온, 상대습도, 풍속, 강수량), DO농도 자료를 사용하였고, 시 예측 학습에는 연속된 자료가 가장 많은 2015년 3월 ~ 12월까지의 데이터를 활용하여 연구를 진행하였다. 모형의 검증을 위해 결정계수(R square)를 이용하여 통계분석을 실시하였다.

• Journal of Microbiology and Biotechnology
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• v.18 no.4
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• pp.718-724
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• 2008

Dissolved oxygen (DO) and shear stress have pronounced effects on hyaluronic acid (HA) production, yet various views persist about their effects on the molecular weight of HA. Accordingly, this study investigated the effects of DO and shear stress during HA fermentation. The results showed that both cell growth and HA synthesis were suppressed under anaerobic conditions, and the HA molecular mass was only $(1.22{\pm}0.02){\times}10^6 Da$. Under aerobic conditions, although the DO level produced no change in the biomass or HA yield, a high DO level favored the HA molecular mass, which reached a maximum value of $(2.19{\pm}0.05){\times}10^6 Da$ at 50% DO. Furthermore, a high shear stress delayed the rate of HA synthesis and decreased the HA molecular weight, yet had no clear effect on the HA yield. Therefore, a high DO concentration and mild shear environment would appear to be essential to enhance the HA molecular weight.

• Water for future
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• v.17 no.2
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• pp.85-97
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• 1984

Measuring the river flow and water quality in the midstream of the Nakdong River, the natural purification status in examined through the analyses of the elements which affect the variation of dissolved oxygen, and DO model is evaluated to the midstream reach of the river. The major results of this study are as follows; the pruification factor of the of the river is relatively high, it is worried over eutrophication considering much production of algae, and it is evaluated that important factor affecting the DO value computed by the proposed DO model are in order of reaeration coefficient, carbonaceous BOD and deoxygenation constant.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.7-10
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• 2003

Factors affecting filtration performance were investigated in a Sequencing Batch Reactor (SBR) coupled with a submerged microfiltration module. Special bioreactors for aerobic and anoxic phases, respectively, were specifically designed in order to differentiate tile effect of Dissolved oxygen (DO) from that of mixing intensity on membrane filterability. DO concentration as well as mixing intensity proved to have a major influence on the membrane performance regardless of the SBR phase. A higher DO concentration resulted in a slower rise in TMP, corresponding to less membrane fouling.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.86-88
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• 1996

A method is presented for the development of the PC-based measurement system on the 6 cathodes-single anode type multi-functional oxygen electrodes for detecting various components of the solution by measuring the dissolved oxygen(DO) concentration. The system is consisted with the 6 channel sensor signal modyfing circuits for the sensor and the PC interface circuits using the single chip microprocessor 80c196kc. Typical polarograms for the DO probes under test using this sensor circuits are presented. This system covers wide range of measuring time from 300sec to over 16 hour in one measurement step by programming the 9 monitor disply mode.

• Journal of Environmental Science International
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• v.8 no.3
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• pp.349-354
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• 1999

The transfer function was introduced to establish the prediction method for the DO concentration at the intaking point of Kongju Water Works System. In the mose cases we analyze a single time series without explicitly using information contained in the related time series. In many forecasting situations, other events will systematically influence the series to be forecasted(the dependent variables), and therefore, there is need to go beyond a univariate forecasting model. Thus, we must bulid a forecasting model that incorporates more than one time series and introduces explicitly the dynamic characteristics of the system. Such a model is called a multiple time series model or transfer function model. The purpose of this study is to develop the stochastic stream water quality model for the intaking station of Kongju city waterworks in Keum river system. The performance of the multiplicative ARIMA model and the transfer function noise model were examined through comparisons between the historical and generated monthly dissolved oxygen series. The result reveal that the transfer function noise model lead to the improved accuracy.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.790-794
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• 1989

A novel control method involving an automatic tuning of digital PID controller parameters has been developed for better regulation of DO (dissolved oxygen) concentration in batch fermentation processes. Heuristic reasoning allows the PID controller to reach improved tuning decisions based upon the supervision of certain control performance indices in the same cognitive manner as in an expert control.

• Journal of People, Plants, and Environment
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• v.24 no.6
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• pp.609-617
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• 2021

Background and objective: The nanobubbles remain stable in water, and it increased dissolved oxygen (DO) in the water that promotes the seed germination and the plant growth. We evaluated the seed germination and growth of sprouts (radish, wheat, and barley) and leafy vegetables (red mustard and pak choi) when irrigated with various DO of nanobubble water (NB). Methods: The oxygen NB was generated by surface friction and treated in 4 levels: NB 0% (control, DO 9.21 mg·L^-1), NB 20% (DO 15.40 mg·L^-1), NB 33% (DO 20.93 mg·L^-1), and NB 100% (DO 39.29 mg·L^-1). Results: The root length of radish and wheat increased more in NB 33% than the control plot. The fresh weight increased in NB 33% compared to the control plot in radish and wheat, and both fresh and dry weight increased more in NB 20%, NB 33%, and NB 100% than the control plot of barley. The leaf length and width of red mustard decreased more in NB 33% and NB 100% than the control plot and NB 20%, which indicated the leaf compactness. The fresh and dry weight of shoot and root increased more in NB 100% than the control plot in red mustard. In pak choi, the shoot fresh weight increased more in NB 100% than the control plot. In leafy vegetables, the germination rate of red mustard in NB 100% was higher than the control plot, however, it was not significantly different between oxygen NB plots in sprout vegetables. Conclusion: The results showed that the root growth and biomass increased after applying NB 33% in sprout vegetables. The leaf growth properties as the number of leaves and leaf size were not significantly different or decreased in NB treatments compared to control plots, but NB 100% (DO 39.29 mg·L^-1) effectively increased the root growth and plant biomass in leafy vegetables.

• Journal of Aquaculture
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• v.8 no.4
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• pp.251-260
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• 1995

Experimental transportations of the olive flounder (Paralichthys olivaceus) seedlings (body weight $2.1\pm0.39g$) with polyethylene vinyl bag were Performed to study the change of dissolved oxygen (DO) during transportation, survival rate and feeding activity of seedlings after transportation. The distance and time required for the transportations were 272 km and 11 hours, respectively. DO was rapidly decreased within 3 hours (P<0.05) during the transportation of seedlings of 40 fish in 10l of sea water at $15.6\~17.8^{\circ}C$ of initial water temperature with 5 ml/l of initial DO. The decreasing tendency of DO (Y) according to elapsed time (X) was expressed an equation of $Y\;=\;2.7444X^{-0.4780}$ (r=0.8071). Feeding activity of the seedlings after transportation supplemented with oxygen and icepack besides above transport conditions was significantly higher than that of fish supplemented with icepack only (P<0.05). It was desirable to starve the seedlings for 36 hours before transportation. Survival rate of seedlings was greatly reduced, when the dissolved oxygen concentration was lowered below the range of $0.7\~0.94ml/l$ just after transportation.

• Journal of Environmental Impact Assessment
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• v.28 no.1
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• pp.49-62
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• 2019

Environmental changes can affect life-history traits, such as growth rate and reproduction, and organisms adapt on a given environmental condition to maximize ecological fitness. This study shows the effects of water temperature and dissolved oxygen level on early growth and accumulated damage in fish using a dynamic-state-dependent model. I have hypothesized that the level of foraging activity is related to growth and stress and so the optimal level can maximize reproductive success - ultimately, fitness. The critical temperature and dissolved oxygen (DO) is also defined as inducing the maximum growth rate at the level. So, the model predicts the highest growth rate at oxygen saturation and lower growth rate at lower or higher level of DO in water. Lower DO (i.e., hypoxia) causes slower growth rate through higher amount of accumulated stress whereas higher DO (i.e., hyperoxia) induces faster growth rate, but smaller body size. In addition, I show that there is lower impact when considering simple or independent environmental factors on environmental assessment. My findings suggest that multiple environmental factors as physiological ecology approach should be considered to improve impact assessment in environmental changes and a further study is needed to develop advanced assessment tools considering multiple environmental factors.