• 환경위생공학
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• 제9권2호
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• pp.50-57
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• 1994

Densities of total and injured coliforms in treated water( TW ) and three tap water salt pies( Taps Kl, K2 and K3) of Ku- eui water treatment plant and one tap water sample( Tap T) of Tuk- do water treatment plant were measured 23 times from 1991 to 1992. Coliform regrowth in the water distribution system occurred three times during the study period. When the regrowth episode occurred, injured coliforms were always but total coliforms were not always detected in treated water. Mean densities of total coliforms in TW, and Taps Kl, K2, K3 and T were 0.8, 2.3, 1.9, 1.4 and 2.1 cfu/100mℓ by membrane filtration method using m- TF agar and those of injured coliforms were 3.4, 2.8, 2.5, 2.7 and 2.9 c1u/100mℓ using mondo- LES agar. The injury rates of TW and Taps Kl, K2, K3 and T were 89.5,77.4,67.9, 82.8 and 75.9%, respectively. The high injury rate of coliform bacteria in Seoul water supply can cause regrowth problems in distribution systems due to the repair of injured cells under an appropriate condition. It is recommended the injured coliforms should be measured in drinking water since they can lead to a significant underestimation of total coliforms and result in an inaccurate evaluation of the potential health risks.

• 융합신호처리학회논문지
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• 제8권3호
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• pp.211-216
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• 2007

대형 정수장에서 개인수도꼭지까지 전체 급수 설비에서 수질은 반드시 먹는 물 수질기준을 만족해야 한다. 그러나 현재까지도 수돗물의 공급과정은 과학적으로 모니터링 되거나 관리되지 못하고 있다. 수돗물 특히 대부분의 작은 규모의 정수장은 항상 다양한 오염원 및 불순물 등에 노출되어 있다. 최근 일부 대형 정수장이나 배수지 등에 수질감시 시스템이 사용되고 있다. 특히 인터넷을 이용한 수질 모니터링 방법이 일부 지방자치단체에 도입되었으며 이 시스템은 해당 지역주민들이 언제 어디서나 수질을 확인할 수 있도록 되어있다. 그러나 이 시스템, 즉 대형 시스템에 사용되는 이 방법은 매우 높은 비용을 필요로 하고 이로 인해 아파트, 공공시설, 소규모의 지하저수조 및 고가(高架)저수조와 같은 소규모 급수설비에는 적용하기가 곤란하다. 따라서 본 연구에서는 저가의 개별 수질측정 센서모듈에 대한 통합시스템을 제안한다. 개발된 통합 시스템과 인터넷상에서 동작하는 모니터링 프로그램을 이용하여 저수조 시스템 관리자는 음용수에 대한 수질 특성치를 실시간으로 관리할 수 있다. 또한 제안된 시스템이 모듈화 되어있기 때문에 크고 작고의 규모에 관계없이 저비용으로 다양한 저수조나 정수장에 쉽게 설치할 수 있다.

• 융합신호처리학회논문지
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• 제10권3호
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• pp.207-213
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• 2009

정수장에서 수도꼭지까지 전체적인 물 공급 체계에서 수돗물의 수질은 먹는 물 기준에 적합해야 하지만 수돗물 공급과정에서 수질 모니터링과 충분한 관리가 이루어지지 않고 있다. 특히 대부분의 소규모 저수조(지하저수조 또는 고가(高架)저수조)의 수도관은 다양한 오염원에 노출되어 있다. 최근의 수질 모니터링 시스템은 몇몇 대형 정수장과 배수지 등에 설치되어 운영하고 있다. 특히 인터넷을 이용한 수질 모니터링은 언제 어디서나 주민들이 확인할 수 있도록 몇몇 지방자치단체에서 채택하고 있다. 이러한 시스템을 구축하는 것은 대규모 시설을 필요로 하기 때문에, 아파트, 공공건물, 소규모 지하저수조 또는 고가저수조와 같은 규모가 적은 물 공급시설에는 제한적으로 적용된다. 본 연구에서는 저렴한 각각의 수질센서 모듈을 집적화하여 개발한 다항목 수질계측기를 이용하여 인터넷에서 운용되는 온라인 모니터링 프로그램을 개발하였다. 저수조 관리자는 온라인으로 먹는 물의 수질 측정값을 모니터링할 수 있다. 제안된 다항목 수질측정기를 집적화하였으며, 저수조의 크기와 관계없이 저가로 다양한 저수조에 쉽게 적용할 수 있는 시스템이다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권1호
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• pp.12-18
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• 2011

To investigate the natural reduction characteristics of radon with a short half-life (3.82 day) in drinking Qgroundwater, we analyzed the changes of radon concentrations of groundwater, waters in storage tanks, and tap waters from the small-scale groundwater-supply systems (N = 301) by LSC (Liquid Scintillation Counter). We also analyzed the concentrations of uranium (half-life 4.5 billion years) in the waters by ICP/MS to compare with natural reduction of radon concentration. The radon concentrations of 68 groundwater-supply systems occupying 22.6% of the total samples exceeded the US EPA's Alternative Maximum Contaminant Level (AMCL : 4,000 pCi/L), with the average radon concentration of 7,316 pCi/L (groundwaters), 3,833 pCi/L (tank waters) and 3,407 pCi/L (tap waters). Compared to the radon levels of pumped groundwaters, those of tank and tap waters naturally reduced significantly down to about 50%. Especially, in case of 29 groundwater-supply systems with the groundwater radon concentrations of 4,000~6,000 pCi/L, average radon concentrations of the tank and tap waters naturally decreased down to the AMCL. Therefore this study implies that radon concentrations of drinking groundwater can be effectively reduced by sufficient storage and residence in tanks.

• 환경위생공학
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• 제8권1호
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• pp.67-80
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• 1993

This survey was carried out to take the status of seawater intrusion into groundwater wells located in the eastern area of Chejudo, to get the elementary data which may evaluate the level of would-be groundwater contamination, and to perform effective the effort that will supply the clear water for the residents. The sampling sites were northeastern districts of Haengwon, Handong, and Sangdo, southeastern districts of Susan, Nansan, and Samdal, and northwestern districts, as reference, of Aewol, Keumnung, Panpo, Kosan, Shindo, and Bosung. We collected the samples from the public tap water by month, and analysed electrical conductivity, sodium(Na), potassium(K), magnesium(Mg), calcium(Ca), bicarbonate($HC0_{3^-}$), and items of the criteria as drinking water. In the northeastern districts we also added the sampling sites to survey the fluctuations of dissolved solids according to distance from seashore, including two private boreholes and one public tap water of Dukchun. The result is as follows 1) In the northeastern district, the concentration of chloride ion showed large fluctations from 40mg/l to 100mg/l, but suitable for the criteria of drinking water. It was thought that the drought influenced. 2) In the Sangdo of the northeastern districts, similar tendancy to Hangwon and Handong was showed only in the concentration of chloride ion, but different tendancy was showed in chloride-bicarbonate ratio, calcium-magnesium ratio, and sodium adsorption ratio(SAR). Considering these facts, it was not thought that seawater intruded. 3) The components of Na and Cl showed rapid slope in the northeastern districts above 3km from seashore. 4) In the northwestern districts as reference, the concentration of chloride ion fluctuated slightly according to the sampling sites and dates, and the concentration of nitrate-nitrogen in some sites exceeded the criteria of drinking water. These were thought that the surface contaminants rather than the intrusion of seawater influenced mainly the groundwater, considering the correlation(r=0.732) of chloride ion and nitrate-nitrogen. 5) Then we must consider the regional characteristies of soil profile in order to prevent the contamination of groundwater, and moniter also the movement of main components within the sol1 profile, not only the research of the intrusion of seawater.

• 대한환경공학회지
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• 제31권6호
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• pp.460-466
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• 2009

간이상수도 시스템에서 공급하는 식수는 일정한 잔류 약품(염소)량을 유지해야 하기 때문에 물과 약품의 혼합방법은 매우 중요하다. 본 연구에서는 물과 약품의 혼합방법을 최적화하기 위하여, 4가지 모델에 대한 농도분포 및 혼합지수를 구하였다. 그중 2가지 모델에 대해서는 혼합효과가 높게 나타났다. 하나는 지하수 공급 파이프 중앙에 약품을 공급하는 모델이고, 또 다른 하나는 약품공급 파이프 하류에 반원형태의 블록을 설치한 모델이다. 이러한 모델들은 유동의 확산 및 교란을 야기시켜 혼합효과를 증가시키는 결과를 가져왔다. 이와 같은 수치해석 결과는 최적의 혼합효과를 얻기 위한 시스템을 설계하는데 도움이 될 것으로 기대된다.

• Membrane and Water Treatment
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• 제13권1호
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• pp.39-49
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• 2022

Seawater desalination is doubtlessly a viable option to supply fresh drinking water. Nevertheless, RO (reverse osmosis) desalination plants in specific areas may be intermittently operated to match the imbalance between water demand and supply. Although a handful of works have been done on other membrane systems, few studies have attempted to mitigate fouling in intermittent RO systems. Accordingly, the objectives of this paper were to examine the effect of the intermittent operation on RO fouling; and to compare four intermittent operation modes including feed solution recirculation, membrane storage in the feed solution, deionized water (DI) recirculation, and membrane storage in DI water. Results showed that intermittent operation reduced RO fouling under several conditions. However, the extents of fouling mitigation were different depending on the feed conditions, foulant types, and membrane lay-up methods. When the feed solution was recirculated during the lay-up, the restoration of the flux was less significant than that by the feed solution feed-up. The use of deionized water during the lay-up was effective to restore flux, especially when the feed solution contains scale-forming salts (CaSO₄) and/or colloidal silica.

• 한국환경과학회지
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• 제21권9호
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• pp.1031-1041
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• 2012

This study was carried out to investigate the characteristics of disinfection by-products (DBPs-trihalomethanes (THMs), haloacetic acids (HAAs) and haloacetonitriles (HANs) formation in chlorination of principal raw waters used for drinking water on Jeju Island, Korea. The domestic water supply of other area and humic acid solution (HA) were used as a reference point. The effects of chlorine contact time, solution temperature and pH on DBPs formation potential (DBPFP) were investigated for raw waters. In addition, the effect of $Br^-$ was studied for HA. The DBPFP (THMFP, HAAFP and HANFP) were increased with increasing chlorine contact time. Comparing the individual DBPFPs for raw waters, they decreased in the order of HAAFP > THMFP ${\geq}$ HANFP. As the solution temperature was increased, the THMFP, HAAFP and HANFP increased. With increasing the solution pH, the THMFP was increased, but HAAFP and HANFP were decreased. With the addition of 0.3 mg/L $Br^-$ for HA, the DBPFP was increased and the major chemical species changed: from trichloromethane to dibromochloromethane and tribromomethane for THMs; from dichloroacetic acid and trichloroacetic acid to tribromoacetic acid for HAAs; and from dichloroacetonitrile to dibromoacetonitrile for HANs.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.679-685
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• 2005

In Korea, water management policy had been successfully conducted until late 1980's. During the period, fundamental needs of human-being, such as requirements of drinking and irrigation waters and flood protection for living, had been satisfied. However, most of recent water problems occurred after the late 1980's such as water quality management and new water resources development, have been unresolved and accumulated. Because, our water governing institutions have become ineffective as water management issue has been changed gradually from fundamental human needs such as water supply and/or flood protection to complex/integrated issues, for example, river restoration. To solve those water problems accumulated, we needs a new paradigm of water governing institution such as setting up national water management committee and river basin committee, in order to coordinate water-related ministries' policies and establish national water resources planning in an integrated format.

• 환경위생공학
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• 제17권1호
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• pp.57-62
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• 2002

Carbon cast iron and Zinc coated steel were the most widely used portable water of supply and distribution Pipeline system. The leaching of red water in portable water could produce sericus environmental sanitary problems. Due to the red water was the most alternative to inner scale of metal pipeline. So this study was conducted the impact of red water on scale products, and was evaluated by the corrosive metal contaminants of 20 fears over. Surface tests, metal surface composition measurements of samples XRF, XRD, and SEM(EDS), analysis were used to investigate the corrosion characteristies of carbon cast iron and Zinc coated steel. As the contaminants of Fe increased the red water of carbon castiron pipe increased due to the scale products amount of $Fe_2O_3$ (Hemite).