• Journal of Environmental Health Sciences
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• v.27 no.1
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• pp.27-35
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• 2001

This aim of the work presented in this paper is to investigate the factors that affcet chlorine decay and to develop functional relationships that can be used to enhance the durability of network models. predictive relationships were established that correlated the rate of chlorine decay to the various water conditions such as DOC, N $H_3$-N, initial chlorine, contact time, temperature and pH values. Free chlorine residual decreased with increasing temperature, DOC, N $H_3$-N, reaction time and chlorine dose. At 2$0^{\circ}C$, pH 7, The initial chlorine demand per mg as DOC/L and mg as N $H_3$-N/L was about 0.43, 2.69 mg/$\ell$ respectively at 180 minutes contact time. The Reaction between chlorine and humic acids was lasted intil 48hr, but the reaction between chlorine and N $H_3$-N was almost completed in 180 min. When the temperature is raised by 1$0^{\circ}C$, chlorine is more consumed about 0.25 mg/$\ell$ in the absence of organic substances and it is more consumed about 3.4 mg/$\ell$ in the presence of humic acid (5 mg/$\ell$) in water at pH 7 for 180 min. Regression Analysis created the resulting prediction equation for the chlorine decay in a SPSS package of the computer system. The model is as follows; $C_{t}$=1.239+0.707(Co)-0.000529(Time)-0.0112(Temp)+0.02227(pH)-0.42(DOC)-2.132(N $H_3$-N).).

• Journal of Aquaculture
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• v.16 no.3
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• pp.151-158
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• 2003

This study was conducted to estimate the effects of residual chlorine dioxide ($CIO_2$) in chlorinated seawater on survival and physiological responses (hematocrit: Ht, hemoglobin: Hb, serum electrolyte and glucose levels, and osmolality) of olive flounder, Paralichthys olivaceus. All the flounders were exposed for 10 min to different concentrations of residual $CIO_2$ just after chlorination for 1 min in each experimental aquarium (EA). ClO$_2$-free seawater was continuously supplied to each EA after 10 min exposure to $CIO_2$. By means of probit analysis, the median lethal times (LT$_{50}$, min) of flounder exposed to 0.43 and 0.51 ppm $CIO_2$, were at 103 and 32 min, respectively. In the range from 0.34 to 0.51 ppm $CIO_2$, the values of Ht, Hb, electrolytes and osmolality of fish exposed to $CIO_2$ were significantly elevated as elapsed time and residual concentrations of $CIO_2$ increased after chlorination. The levels of Ht, Hb, electrolytes and osmolality in flounder exposed to 0.27 ppm $CIO_2$ were not significantly different compared to control fish, which were maintained in $CIO_2$-free seawater; however, the levels of serum glucose were significantly increased with elapse times.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.4
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• pp.255-259
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• 1979

Depuration of extraneous substances such as bottom deposit, feces and coliforms from live oyster has been studied. Coliform accumulation of bottom cultured oysters was much higher than that of raft or long line cultured oysters. When the depuration tank designed in this study was adopted, the depuration rate could be diminished to about $50\%$ within one hour treatment. Tho most effective conditions of the tank water for depurating live oysters wer $22^{\circ}C$ in temperature, 8.80 in pH and below about 2 ppm of residual chlorine concentration.

• Environmental Analysis Health and Toxicology
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• v.12 no.3_4
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• pp.23-29
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• 1997

The main reason of applying chlorination is to sterilize microbes existing in the drinking water treatment. But chlorination could lead to the formation of disinfection by-products (DBPs) by the reaction of free chlorine with humic substance in the water. Especially the DBPs including trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and haloketones (HKs) exist in the tap water. The US environmental protection agency (US EPA) defines that trihalomethanes, dichloroacetic acid, trichloroacetic acid, and dichloroacetonitrile among DBPs are probable/possible human carcinogens. US EPA suggests maximum contaminant levels (MCLs) for THMs (80$\mu$g/L) and HAAs (60$\mu$g/L) in drinking water. In Korea, THMs in drinking water has been surveyed but DBPs in general has not been studied in drinking water practically. Therefore only THMs have been regulating as criteria compounds since 1990 but neither HAAs nor HANs. Researches on HAAs are yet to be found. HAA formation potentials(HAAFPs) have not been practiced. HAAs depends on the characteristics of water sources by chlorination. In this study, HAAFPs from three distinct sources were investigated by laboratory chlorination experiments. This study was performed to measure the level of HAAs in drinking water in Seoul area. At April 1996, after collecting the raw waters from the three sites with the different properties, the water samples were chlorinated at various conditions(pH 5.5, pH 7.0 and without pH adjustment) in the state of raw water to have 0. 5mg/L of residual chlorine concentration. And the raw water, treated water, and tap water of water treatment were collected to measure the HAAs concentration. The quantitative analysis of HAAs was conducted by US EPA methods.

• Journal of environmental and Sanitary engineering
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• v.10 no.1
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• pp.106-125
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• 1995

Recently, in accordance with elevation of life style and economics, the public demand became increasingly concerned about drinking water quality. Without an adequate supply of safe water, healthy and comfortable life could not exist. Therefore, the purpose of this study is to provide the guidelines and the basic informations to enable supply of clean, tasty and healthy drinking water acceptable for various demands. We analyzed the quality of tap water, mineral water, purified tap water using home tap water purifier. And we researched on the sense of the public complaint over the tap water. We proposed several items relating to the comfortableness of water quality and the target value. Also we presented a case of water supply system for purity and the points at problem The items and target value are as follows 1. turbidity : not more than 1 degree 2. dry residue : $30~200{\;}mg/{\ell}$ 3. hardness : $10~100mg/{\ell}$ 4. free carbon dioxide : not more than $20mg/{\ell}$ 5. $KMnO_{4}$ consumption not more than $3mg/{\ell}$ 6. odor threshold not abnormal 7. residual chlorine : not more than $0.4mg/{\ell}$ 8. water temperature' not more than $20^{\circ}C$ 9. manganese : not more than $0.01mg/{\ell}$ 10. iron : not more than $0.02mg/{\ell}$ 11. aluminum : not more than $0.1mg/{\ell}$

• Korean Journal of Materials Research
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• v.22 no.1
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• pp.8-15
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• 2012

Silicon-based thin film was prepared at room temperature by an electrochemical deposition method and a feasibility study was conducted for its use as an anode material in a rechargeable lithium battery. The growth of the electrodeposits was mainly concentrated on the surface defects of the Cu substrate while that growth was trivial on the defect-free surface region. Intentional formation of random defects on the substrate by chemical etching led to uniform formation of deposits throughout the surface. The morphology of the electrodeposits reflected first the roughened surface of the substrate, but it became flattened as the deposition time increased, due primarily to the concentration of reduction current on the convex region of the deposits. The electrodeposits proved to be amorphous and to contain chlorine and carbon, together with silicon, indicating that the electrolyte is captured in the deposits during the fabrication process. The silicon in the deposits readily reacted with lithium, but thick deposits resulted in significant reaction overvoltage. The charge efficiency of oxidation (lithiation) to reduction (delithiation) was higher in the relatively thick deposit. This abnormal behavior needs to clarified in view of the thickness dependence of the internal residual stress and the relaxation tendency of the reaction-induced stress due to the porous structure of the deposits and the deposit components other than silicon.

• Korean Journal of Microbiology
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• v.43 no.2
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• pp.106-110
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• 2007

The detection and distribution of Aeromonas in water supplies were investigated by using the USEPA Method 1605. Water samples were collected from the Han River, finished waters and tap waters supplied from Water Treatment Plants in Seoul monthly from July 2002 to December 2003. Aeromonas species in each water sample were quantified based on the development of yellow colonies on the surface of membrane filter using a selective medium (Ampicillin-Dextrin Agar with Vancomycin). The Quality Control (QC) for this study met the acceptance criteria of Method 1605. The concentrations of Aeromonas species in surface water samples ranged from $1.0{\times}10^{0}\;to\;9.8{\times}10^{3}\;CFU/ml$. Aeromonas species were found only in one tap water sample with concentration of 1 CFU/500 ml. No Aeromonas species were found in any finished water samples. Aeromonas species detected here were identified as A. salmonicida(51%), A. caviae(4.7%), A. schubertti(3.4%), A. sobria(3.8%), A. hydrophila(2.1%), and A. ichithiosmia(0.4%). A. salmonicida was the dominant species, which is of no significance to human health. Chlorine resistance of A. salmonicida was evaluated and as a result, 99.99% of A. salmonicida decreased after 30 seconds exposure at residual free chlorine 0.2 mg/L. These suggest that the waters supplied in Seoul may be safe against the pathogenic agent Aeromonas.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.4
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• pp.469-479
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• 2015

This study have been conducted to analyze the feasibility of establishing Contamination Warning System(CWS) that is capable of monitoring early natural or intentional water quality accidents, and providing active and quick responses for domestic C_water supply system. In order to evaluate the water quality data set, pH, turbidity and free residual chlorine concentration data were collected and each statistical value(mean, variation, range) was calculated, then the seasonal variability of those were analyzed using the independent t-test. From the results of analyzing the distribution of outliers in the measurement data using a high-pass filter, it could be confirmed that a lot of lower outliers appeared due to data missing. In addition, linear filter model based on autoregressive model(AR(1) and AR(2)) was applied for the state estimation of each water quality data set. From the results of analyzing the variability of the autocorrelation coefficient structure according to the change of window size(6hours~48hours), at least the window size longer than 12hours should be necessary for estimating the state of water quality data satisfactorily.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.3
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• pp.296-308
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• 2010

The peroxone process overcomes many of the limitations associated with conventional and advanced water treatment systems using chlorine disinfection and ozone oxidation processes. Ozone and hydrogen peroxide generate highly reactive hydroxyl free radical which oxidize various organic compounds and has highly removal efficiency. The key issue to operate peroxone process is developing the method to achieve high process effectiveness when scavengers that inhibit generation of OH radicals or consume OH radicals are co-existing in the process. Also many studies, to minimize inorganic oxidative by-products such as bromate and to reduce disinfection by-products after chlorination behind peroxone process, are needed. And we should consider the excess residual hydrogen peroxide in the water. On-line instruments and control strategies need to be developed to ensure effective and robust operation under conditions of varying load. If problems above mentioned are solved, peroxone process will be applied diversely for water treatment.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.1
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• pp.1-6
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• 2012

Down Stream K River has high COD (4-10 mg/L) and high $NH_3$-N concentration (3.5 mg/L during winter period). Although $NH_3$-N itself is not reported harmful at this level, it must be removed to meet drinking water standard (0.5 mg/L). We constructed a pilot plant modifying the processes of conventional drinking water facilities. Prechlorination and powdered activated carbon (PAC) dechlorination was adopted prior to a flocculation tank to remove ammonia and prevent disinfection byproducts (DBPs) formation. Also, GAC processes was included after sand filter to remove residual DOC. This pilot having a capacity of 36 ton/day was operated for one year. The GAC processes were successful to remove ammonia and many organic pollutants (DOC, MBAS, UV-254 nm absorbance, etc). Influent DOC concentrations were very high as 3~6 mg/L throughout the plant operation. It was impossible to achieve 1.0 mg/L effluent DOC, indicating that bed depth (2 m) should be increased to achieve more strict DOC quality standards. When $Cl_2$ dose was well controlled ($Cl_2/NH_3$-N ratio 10~11 on a weight basis), $NH_3$-N removal was 98% and THMs was very low possibly due to low free residual chlorine and PAC dechlorination.