• Korean Journal of Ecology and Environment
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• v.54 no.3
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• pp.240-246
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• 2021

The Chironomidae is a benthic macroinvertebrate commonly found in freshwater ecosystems, along with Ephemeroptera and Trichoptera, which can be used for environmental health assessments. There are approximately 15,000 species of Chironomidae worldwide, but there are limited studies on species identification of domestic Chironomidae larvae. In the present study, we carried out species classification of the Chironomidae larvae that found in Jeju's tap water purification plants using morphological characteristics and genetic identification based on cytochrome c oxidase subunit I (COI) gene of the mitochondrial DNA. Body shape, mentum, antenna, mandible in the head capsule, and claws were observed in the larvae for morphological classification. Analysis of 17 larvae collected from faucets and fire hydrants of domestic tap water purification plants revealed the presence of two species, including 14 Orthocladius tamarutilus and 3 Paratrichocladius tammaater. These results will aid the use of the criteria information about species classification of the Chironomidae for water quality management in water purification plants and diversity monitoring of freshwater environments.

• Analytical Science and Technology
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• v.15 no.2
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• pp.172-179
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• 2002

Determination were performed for the presence of three common environmental endocrine disrupting compounds (EDC), namely nonylphenol (NP), octylphenol (OP), di(2-ethylhexyl)phthalate (DEHP) in rainwater, distilled water, millipore water, groundwater, tap water, and bottle water in market, using OASIS cartrige extraction and GC/MS-SIM. Octylphenol was not detected in any water samples. The order of nonylphenol concentrations were increased in rainwater < millipore water < distilled water < groundwater < tap water < bottle water. The concentration of nonylphenol in bolltle water was $0.44{\mu}g/L$(ppb) at highest. Di(2-ethylhexyl)phthalates were detected in every water samples, and the concentrations were to be $1.70{\sim}2.92{\mu}g/L$ in rainwater, $8.7{\sim}31.7{\mu}g/L$ in distilled water, $0.6{\sim}5.6{\mu}g/L$(mean: $2.5{\pm}0.3{\mu}g/L$) in millipore water, and that were very stable values than other waters, $1.1{\sim}6.0{\mu}g/L$ in groundwater at near Jeonju, $3.1{\sim}5.8{\mu}g/L$ by means in tap water, $0.5{\sim}67.6{\mu}g/L$ in bottle water from market. The concentration of DEHP in bottle water samples from market were in higher than USEPA regulation at over 40%.

• Korean Journal of Microbiology
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• v.31 no.3
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• pp.255-260
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• 1993

The Enterobacter cloacae biofilms developed on slide glasses and galvanized-iron coupons were applied to test the attached bacterial resistance to chlorination. The chlorine resistances of biofilm bacteria grown on the slide glasses and galvanized-iron coupons were 14 and 480 times that of the suspended bacteria, respectively. The chlorine resistance of particleattached bacterial populations was 48 times that of suspended bacterial populations. The biofilm bacterial densities developed on the slide glasses and galvanized-iron coupons which were immersed in the flowing tap water for 75 days were $4.75 {\times} 10^{4}$ and $1.12 {\times} 10^5 cfu/cm^{2}$ It is concluded that main mechanisms of enteric or HPC bacterial resistance to chlorination in tap waters are bacterial attachment or . adsorption to particles or bacterial aggregations and formation of biofilms on the inner wall of distribution systems by escaped bacteria from chlorination in water treatment processes, which results in bacterial regrowth in water distribution systems.

• Analytical Science and Technology
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• v.23 no.6
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• pp.551-559
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• 2010

This study was conducted to establish an analytical method for the determination of seven nitrosamines in chlorinated tap water by precolumn derivatization followed by high performance liquid chromatography coupled with fluorescence detection. The derivatization procedure was optimized for denitrosation and dansylation, and then two extraction methods, liquid-liquid extraction (LLE) with dichloromethane and solid phase extraction (SPE), were compared. The SPE method employing the optimized derivation procedure showed higher extraction recovery (54.4-88.7%) and reproducibility (1.9-19.4%) than the LLE method (51.4-87.7% and 4.2-33.3%, respectively). The method detection limits were between 0.5 and 4.4 ng/L. When chlorinated water samples were collected from two treatment plants and ten household taps, and analyzed for nitrosamines, Nnitrosodimethylamine (NDMA) was the major compound found between 26.1 and 112 ng/L.

• Journal of Environmental Health Sciences
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• v.3 no.1
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• pp.48-52
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• 1976

A study was carried out to investigate the sanitary condition of 107 wells in Jungil Ri, Kyunggi province and Daeso Ri, Choongbuck province, from July 1, to August 30, 1975. In this study, coliform groups were examined by the membrane filter method as well as general sanitary condition, pH value, ammonia nitrogen, hardness and water temperature. The following results were obtained: 1. Average value of general sanitary condition in the wells were 15$\circ$C in temperature, pH 6.4, hardness 124ppm and Cl ion 34ppm. 2. Coliform group was positive at all out of 30 open wells and 33 out of 45 pumped wells, while only 7 out of 32 tap water in the simple typed water supply system showed the evidence of coliform groups. 3. The positive rate of ammonia nitrogen revealed 13% out of 107 wells and that of nitrite nitrogen was 36.4% and 6 wells rate of 5.6% were ammonia nitrogen and nitrite nitrogen positive at same time. 4. Colflorin group positive of 32 tap water in the simple typed water supply system 3(27%) out of 11 samples with no residual chlorine, 3(17%) out of 17 with 0.1 to 0.5ppm, 1 out of 3 with 0.6 to 1.0 ppm and none out of 1 with 1.1 to 1.5 ppm.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.4
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• pp.187-202
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• 2023

This study focuses on the application of a new measurement method that quantifies the residual color of filtered water using a spectrocolorimeter after filtering the discolored substances. It was confirmed through the color and turbidity cross-test that the discolored substances cannot be measured effectively with the current legal color and turbidity test method. Therefore, the National Institute of Environmental Research's filter testing method, which involves filtering the sample through 0.45 ㎛ filter and visually inspecting the color, was improved. A membrane filter colorimetry (MFC) method was established by measuring the color difference (ΔE*ab(65)) of the filtered filter using a spectrophotometer and expressing it as filter color unit (FCU). Using the MFC method, the FCU for reference materials such as iron and manganese, as well as field samples, was measured. The results showed a high correlation with turbidity, and the color difference patterns varied depending on the type of reference materials and field samples. This indicates that the MFC method is an effective new measurement method of discolored tap water.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.1
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• pp.47-56
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• 2023

This study describes the successful synthesize strategy for the silica nanoparticles utilizing various water sources, including tap, industrial, and stream waters without using deionized water. Also, as-synthesized silica nanoparticles are employed as dispersive materials for the electro-responsive smart fluid application. Specifically, homogeneous silica nanoparticles with sizes of 500-700nm are successfully prepared in large scale at once (ca. 12.0 g) with the described experimental method and showing similar structural and chemical characteristics with silica nanoparticles synthesized using the deionized water. The size of silica nanoparticles are varied according to the ion conductivity differences of tap, industrial, stream water, and deionized water. The size of silica nanoparticles decresed with the increased ion conductivity, indicating the ion suppression of growth of silica nanoparticles. Moreover, as-synthesized silica nanoparticles from various water sources of electro-responsive characteristic are investigated by the smart fluid application. The smart fluids containing silica nanoparticles synthesized by tap, industrial, and stream water exhibited higher shear stress compared to the deionized water, owing to the more rigid fibril-like structures formed by the smaller silica nanoparticles. Conclusively, uniform silica nanoparticles from various water sources without any purification are able to successfully prepared without usage of deionized water and resulting silica nanoparticles manifested higher electro-responsive performance.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.9
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• pp.900-904
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• 2010

Polyvinyl chloride (PVC) hoses, polyethylene hose and silicone hose for tap water were tested with respect to migration of phenolic compounds to water. The highest concentrations (0.36~1.97 mg/L) of total phenolic compounds were observed in the test water from PVC hoses. Increasing residual Cl concentration from 0 to 0.5 mg/L or increasing water temperature from 4 to $25^{\circ}C$ increased 3~3.2 times and 100~104 times for migrated total phenolic compounds concentrations, in respectively. A major migrating phenolic compounds from PVC hoses were bisphenol-a (BPA) and it was observed that the concentration of migrating phenolic compounds in the order: DEHP > 2-chlorophenol > 2,4,6-trichlorophenol > 2,4-dichlorophenol from PVC hoses.

• Korean Journal of Medicinal Crop Science
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• v.23 no.4
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• pp.292-297
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• 2015

This study was carried out to have the basic and applied informations relating to develop the cultivation methods and to increase the productivity and quality of ginseng. 1 to 6 year old ginsengs of Jakyung cultivar were cultivated and the content and synthetic amount of carbohydrates were investigated with different plant tissues, growth stages, and years old. The concentration of total carbohydrates at six year old ginseng including water soluble and water insoluble carbohydrates was about 18.9%, 42.9%, and 43,6% in leaves, tap roots, and lateral roots, respectively. Water soluble carbohydrate of tap and lateral roots was slightly decreased from August until September, and then increased on November, whereas its water insoluble carbohydrate was increased from August to September and then decreased on November. Comparing with the content of carbohydrates of 1 to 6 year old ginsengs, it was continuously increased from one year old ginseng until five year old ginseng, however it was not increased much in six year old ginseng. The highest content of carbohydrates was at five year-old in all tissues of ginseng. Water soluble and water insoluble carbohydrates were significantly shown different in leaves, stems, tap roots, and lateral root at different growth stages and with different years old. The content of water soluble carbohydrate in the leaves was remarkedly higher compared to that of water insoluble carbohydrate, while in the root the content of water insoluble carbohydrate was clearly higher compared to the water soluble carbohydrate. Comparing with the synthetic amount of carbohydrates, water soluble carbohydrates was higher in the shoot than that in the root, whereas water-insoluble carbohydrates higher in the root than that in the shoot. Carbohydrates which would be utilized in ginseng tissues for short and long-term periods as major energy were appeared differently in between shoot and root, with different growth stages, and years old.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.313-324
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• 2011

Several complaints from consumers on red or turbid waters were often filed at the same places although various efforts were made to improve water quality in the drinking water plant. The red water problems were occurred due to corrosion of main water pipe, especially at extremity. The low concentrations of chlorine indicating poor water quality were detected at the problematic location. To solve the poor water quality at the extremity, flushing techniques, i.e., conventional flushing, unidirectional flushing, and continuous flushing, were recently practiced. In this study, effects of conventional flushing on water qualities were examined by comparing turbidity and residual chlorine before and after flushing. In addition, more detailed analyses on water qualities at the tap water were conducted to learn a reduction pattern during flushing. Five items from geographic information system of water distribution were used to obtain a relationship with water quality, washing duration or amounts of washing water. The flushing was effective to meet the National Drinking Water Quality Standard with simple and relatively short time operation. The key operational parameter in flushing was amounts of washing water which should be estimated based on water quality of the consumer's tap water. The positive relationship between the residual chlorine and pipe length implied that detention time in the pipeline was the main cause of the complaints. More experiments on effectiveness of flushing are needed to determine reasonable strategies of flushing.