• 식물병연구
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• 제27권4호
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• pp.149-154
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• 2021

Pseudoperonospora cubensis는 오이를 포함한 박과작물에 강한 병원성을 나타낸다. 이러한 노균병의 친환경 방제를 위하여 이산화염소수를 적용하였는데, 희석 분무살포하는 경우에 41.2%의 방제효과가 있었지만, 가열연막살포한 경우에는 80.9%의 높은 방제효과를 얻을 수 있었다. 이러한 결과로 노균병과 같이 습도에 큰 영향을 받는 병해의 친환경 방제 시 연막 방제는 기존의 희석살포 방제법보다 더욱 효과적으로 적용 가능한 것을 확인할 수 있었다.

• 전기전자학회논문지
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• 제6권2호
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• pp.146-151
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• 2002

본 논문은 RTOS를 이용하여 정수장의 염소투입을 실시간으로 제어할 수 있는 시스템을 제안하였다. 기존 정수장의 염소투입방식은 유량방법을 이용하여 제어하였으며 계절이나 시간 또는 물의 사용량과 같은 외부환경에 대한 적절한 제어가 불가능 하였다. 따라서 본 논문에서는 유량방법과 잔류염소방식의 2가지 방법으로 시스템을 설계하고, RTOS의 각 태스크는 외부 환경 변화를 실시간으로 체크하여 염소농도 조절에 이용되는 연산의 보정값을 조절할 수 있도록 프로그램 하였다. 제안한 시스템을 2곳의 정수장에 설치하고 설정을 1.2ppm으로 하여 실험한 결과 1.21ppm의 평균값을 유지하였으며 최대, 최소의 편차 또한 0.3ppm으로 기존 정수장보다 우수한 성능을 나타내었다.

• Environmental Engineering Research
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• 제19권4호
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• pp.375-380
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• 2014

Macro fouling due to blue mussels (Mytilus edulis) has affected negatively on the operation efficiency and eventual system failure of offshore structures and coastal power stations. A certain range of chlorine (0.05, 0.1, 0.3, 0.5, 0.7 and 1.0 mg/L) was applied on the mussel larvae to identify the survival rate with respect to various exposure times under laboratory condition. The ciliary movement of the larvae was used to check their survival. The 1.0 mg/L of chlorine shows to 97% of larvae mortality whereas 0.7 mg/L of chlorine shows only 16% of larvae mortality. Minimum exposure times for 100% larvae mortality ranged from 300 to 20 min for increasing concentrations of chlorine (0.05~1.0 mg/L). It was found that 1 mg/L of chlorine was 4 times more efficient than 0.7 mg/L of that, and 15 times more than 0.05 mg/L of chlorine dose. Data collected and analyzed here will help plant operators to optimize chlorine dosage and its scheduling.

• Membrane and Water Treatment
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• 제10권6호
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• pp.395-404
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• 2019

The influence of chlorine on marine bacterial communities was examined in this study. A non-chlorine-adapted marine bacterial community (NCAM) and a chlorine-adapted bacterial community (CAM, bacterial community treated with $0.2mg-Cl_2/L$ chlorine) were cultivated for 1 month. A distinct difference was observed between the NCAM and CAM, which shared only eight operational taxonomic units (OTUs), corresponding to 13.1% of the total number of identified OTUs. This result suggested that chlorine was responsible for the changes in the marine bacterial communities. Kordiimonas aquimaris was found to be a chlorine-resistant marine bacterium. The effect of intermittent chlorination on the two marine biofilm communities formed on the reverse osmosis (RO) membrane surface was investigated using various chlorine concentrations (0, 0.2, 0.4, 0.6 and 0.8 mg $Cl_2/L$). Although the average number of adherent marine bacteria on the RO membrane over a period of 7 weeks decreased with increasing chlorine concentration, disinfection efficiencies showed substantial fluctuations throughout the experiment. This is due to chlorine depletion that occurs during intermittent chlorination. These results suggest that intermittent chlorination is not an effective disinfection strategy to control biofilm formation.

• 상하수도학회지
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• 제21권5호
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• pp.601-607
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• 2007

In order to maintain constant residual chlorine in sedimentation basin, It is necessary to develop real time prediction model of residual chlorine considering water treatment plant data such as water qualities, weather, and plant operation conditions. Based on the operation data acquired from K water treatment plant, prediction models of residual chlorine in sediment basin were accomplished. The input parameters applied in the models were water temperature, turbidity, pH, conductivity, flow rate, alkalinity and pre-chlorination dosage. The multiple regression models were established with linear and non-linear model with 5,448 data set. The corelation coefficient (R) for the linear and non-linear model were 0.39 and 0.374, respectively. It shows low correlation coefficient, that is, these multiple regression models can not represent the residual chlorine with the input parameters which varies independently with time changes related to weather condition. Artificial neural network models are applied with three different conditions. Input parameters are consisted of water quality data observed in water treatment process based on the structure of auto-regressive model type, considering a time lag. The artificial neural network models have better ability to predict residual chlorine at sediment basin than conventional linear and nonlinear multi-regression models. The determination coefficients of each model in verification process were shown as 0.742, 0.754, and 0.869, respectively. Consequently, comparing the results of each model, neural network can simulate the residual chlorine in sedimentation basin better than mathematical regression models in terms of prediction performance. This results are expected to contribute into automation control of water treatment processes.

• 환경위생공학
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• 제6권2호
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• pp.33-47
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• 1991

1. Water supply treatment plants personnel could not test the water quality control, because most of them rely on the provincial health laboratories about water quality rely rant test. However, in future, plants have to been provided the facilities and equipment of water quality laboratory. 2. Chlorination methods are 89.5% of liquid chlorine and 10.5% of solid chlorine, and the cost per 1 $\m^{3}$ of chlorination is about 1.30 won which chlorination cost is very cheap as 1/142 of drinking water production cost. Input method of chlorine is 35% of automatic method, 56% of semi-automatic, and 9% of other methods, and this is no problem 3. Residual effects of chlorination, in the case of distilled water as a standardized material and 0.2 ppm of seperated residual chlorine, were continued 32 hours in $0^{\circ}C$, and 25 hour in $20^{\circ}C$, of water temperature and in the case of 0.4 ppm of seperated residual chlorine were continued 47 hours in $0^{\circ}C$ and 23 hours in $20^{\circ}C$. 4. In the case of 4 ppm of seperated residual chlorine, residual effects were continued 23 hours in $5^{\circ}C$, 90 hours in $10^{\circ}C$, 78 hours in $15^{\circ}C$, and 60 hours in $20^{\circ}C$ : by the temper; lure of water, continuing residual effects of chlorination are different, so we have to car for the warm season chlorination in the hider temperature. 5. Chlorination effects of drinking waters in the case of 0.4 ppm of seperated residual chlorine were continued 237 hours in $22^{\circ}C$ water : and in the case of rechlorination as 4 ppm of residual chlorine, continued 71 hours in $22^{\circ}C$ water.

• Corrosion Science and Technology
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• 제17권1호
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• pp.12-19
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• 2018

Langelier Index (LI) is used as a tap water corrosiveness index. Residual chlorine in tap water induces corrosion inside water pipes. This study takes a deeper look into the effect of residual chlorine in water pipes. Comparison between tap waters of Y and K water treatment plant (WTP) shows that the LI index of K WTP is lower than that of Y. However, the corrosion rate of Y WTP is higher than that of K WTP. This means that the higher the concentration of residual chlorine in tap water, the higher the corrosion rate of pipe materials. When calcium hydroxide was added to tap water, the corrosiveness index was improved and thus the corrosion rate reduced. It is possible to increase the disinfection efficiency by increasing the duration of residual chlorine and suppressing the rust generation of water pipes and to supply minerals. A guideline for corrosion control with residual chlorine should be set up. The effects of residual chlorine should be included in the corrosiveness index of tap water.

• 신재생에너지
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• 제4권2호
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• pp.81-86
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• 2008

Rotary kiln in cement work has been evaluated for a wide variety of organic wastes such as wood, used tyres, plastic wastes and automobile shredder residue (ASR). However the presence of chlorine hampers the use of ASR as fuel in rotary kiln. Therefore, the behavior characteristics of chlorine components in rotary kiln should be considered to develop an effective method for ASR treatment to recovery energy resources. The aim of this paper is to present the chlorine control system applied to a cement manufacturing process for ASR use as an alternative fuel. In this work, the simulation of bypass unit and cyclones for chlorine control in rotary kiln has been studied and compared with the operation results of field test.

• 상하수도학회지
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• 제22권2호
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• pp.213-218
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• 2008

Prediction models for post-chlorination require complicated information of reaction time, chlorine dosage considering flow rate as well as environmental conditions such as turbidity, temperature and pH. In order to operate post-chlorination process effectively, the correlations between inlet and outlet of clear well were investigated to develop prediction models of chlorine dosages in post-chlorination process. Correlations of environmental conditions including turbidity and chlorine dosage were investigated to predict residual chlorine at the outlet of clear well. A linear regression model and autoregressive model were developed to apply for the post-chlorination which take place time delay due to detention in clear well tank. The results from autoregressive model show the correlationship of 0.915~0.995. Consequently, the autoregressive model developed in this study would be applicable for real time control for post chlorination process. As a result, the autoregressive model for post chlorination which take place time delay and have multi parameters to control system would contribute to water treatment automation system by applying the process control algorithm.

• 상하수도학회지
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• 제20권1호
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• pp.86-93
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• 2006

In the drinking water treatment, the aesthetic and color problem are caused by the manganese which is occurring and present in the surface, lake and ground water. The most common treatment processes for removing manganese are known for oxidation followed by filtration. In this study, the manganese sand process was used for removing manganese with river bank filtrate as a source. In the manganese sand process, the residual chlorine and pH are important factors on the continuous manganese oxidation. In addition, space velocity (SV) and alum dosage are play a role of manganese removal. Even though manganese removal increased with increasing chlorine concentration, the control of residual chlorine is actually difficult in this process As the results of tests, the residual chlorine concentration as well as manganese removal were effectively achieved at pH 7.5. The optimum attached manganese concentration on manganese sand was confirmed to 0.3mg/L by the experimental result of a typical sand converting to manganese sand.