• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.146-146
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• 2021

A contamination event occurring in water distribution networks (WDNs) needs to be handled with the appropriate mitigation strategy to protect public health safety and ensure water supply service continuation. Typically the mitigation phase consists of contaminant sensing, public warning, network inspection, and recovery. After the contaminant source has been detected and treated, contaminants still exist in the network, and the contaminated water should be flushed out. The recovery period is critical to remove any lingering contaminant in a rapid and non-detrimental manner. The contaminant flushing can be done in several ways. Conventionally, the opening of hydrants is applied to drain the contaminant out of the system. Relying on advanced information and communication technology (ICT) on WDN management, warning and information can be distributed fast through electronic media. Water utilities can inform their customers to participate in the contaminant flushing by opening and closing their house faucets to drain the contaminated water. The household draining strategy consists of determining sectors and timeslots of the WDN users based on hydraulic simulation. The number of sectors should be controlled to maintain sufficient pressure for faucet draining. The draining timeslot is determined through hydraulic simulation to identify the draining time required for each sector. The effectiveness of the strategy is evaluated using three measurements, such as Wasted Water (WW), Flushing Duration (FD), and Pipe Erosion (PE). The optimal draining strategy (i.e., group and timeslot allocation) in the WDN can be determined by minimizing the measures.

• Journal of Preventive Medicine and Public Health
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• 제38권4호
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• pp.457-464
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• 2005

Objectives : An outbreak of salmonellosis occurred among the student s and staff of D primary school in Yeongcheon-si, 2004. This investigation was carried out to prevent any recurrence of this outbreak and to study the infection source and transmission of the salmonellosis. Methods : The authors conducted a questionnaire survey among 1,205 students and staff members from D primary school about the ingestion of the school lunch and drinking water, and the manifestation of their symptoms. The author examined rectal swabs, the tap water and microorganism cultures, and we also investigated the dining facility and water supply facility. Results : The diarrheal cases were defined as the confirmed cases or the persons who had diarrhea more than one time with symptoms such as fever, vomiting and tenesmus. The diarrheal attack rate was 28.0%. Ingestion of fried bean curd with egg had a significantly high association with the diarrheal attack rate (p<0.05), and the relative risk of the fried bean curd with egg was 10.68 (95% CI=3.88-29.41), as was determined by logistic regression analysis. The bacterial counts in the tap water of the food preparation room and toilet (first floor) exceeded the maximum permissible counts. S. Enteritidis bacteria were only cultured from the fried bean curd with egg of all the supplied foods on September 3, 2004. Conclusions : The major cause of salmonellosis was presumed to be the contaminated bean curd via contaminated tap water due to a water leak of a school water pipe. This contaminated bean curd was under prepared, which allowed the S. Enteritidis to survive and multiply prior to its ingestion.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권5호
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• pp.10-19
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• 2012

The aim of this study was to examine chemical and isotopic compositions of groundwater and lake water near an area contaminated by petroleum and to evaluate influence of petroleum on them during the period from March to August 2011. In dry season, $Ca^{2+}$ and $SO{_4}^{2-}$ were dominant in the groundwater and lake water and $Ca^{2+}$ and $HCO{_3}^-$ were significant in wet season. ${\delta}^{18}O$ and ${\delta}D$ of the groundwater and lake water were plotted near LMWL (${\delta}D=8.06{\delta}^{18}O+12.5$). ${\delta}^{18}O$ and ${\delta}D$ of the lake water did not show seasonal variation. However, ${\delta}^{18}O$ and ${\delta}D$ of the groundwater were enriched in wet season compared with those in dry season because of influence of small ponds around wells where evaporation losses were slightly experienced. Redox condition of most lake water was oxidation environment in contact with the atmosphere during the study period. However, redox condition of groundwater was transitional environment in dry season and oxidation environment in wet season because of influence of contaminant such as petroleum. In some groundwater, the concentrations of $NO{_3}^-$ in some groundwater were less than 1 mg/L because of denitrification. Also, $NO{_3}^-$ showed positive correlation with $SO{_4}^{2-}$ and weak negative correlation with $HCO{_3}^-$, because of influence of denitrification.

• 지질공학
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• 제20권1호
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• pp.25-33
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• 2010

연구지역의 오염된 대부분의 지하수는 상부의 오염된 천부지하수가 지하수공내로 유입되면서 질산성질소로 오염되었다. 공내 카메라 검층 결과 오염된 공들은 그라우팅 불량과 찢어진 유공관으로 인하여 오염된 천부지하수가 공내로 유입되어 지하수질을 악화시켰다. 오염된 천부지하수는 야외 지질조사시 확인된 동남동-서북서 방향, 북북서 방향, 북서-남동 방향, 남북 방향의 단층 및 절리, 파쇄대를 따라서 공내로 유입되었다. 금번 연구의 목적은 질산성질소로 오염된 지하수 공에 대하여 압축패커 기법을 이용하여 상부 오염물질 유입을 차단함으로써 지하수 수질개선 여부를 평가하는 것이다. 본 연구를 위하여 연구지역내 46개소의 지하수공을 대상으로 질산성질소 분석용 시료를 채취하였다. 질산성질소 함량이 10 mg/L 이상으로 먹는물 수질기준을 초과하거나 먹는물 수질기준에 가까운 공은 9개소로 전체 시료수의 약 20%이다. 압축패커 장치를 설치한 후 모든 공들의 질산성질소 함량이 설치 전에 비하여 26~81% 감소되었다.

• 한국환경농학회:학술대회논문집
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• 한국환경농학회 2009년도 정기총회 및 국제심포지엄
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• pp.344-344
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• 2009

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2004년도 학술대회지
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• pp.107-125
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• 2004

A bioremediation of petroleum-contaminated soil in Korea was evaluated for the optimization of enhanced biodegradation and the minimization of effects of seasonal variations, The short-term bioremediation in combination of biopile pretreatment and landfarming was performed by lowering contaminated levels and overcoming the inhibiting factors in the rainy and winter seasons. A microbial density was maintained with indigenous microbial addition for bioaugmentation and with fertilizers for biostimulation. A lesser volatile and biodegradable fraction due to their abiotic removals following the biopile pretreatment was effectively removed by the laterally applied landfarming. The optimal temperature in greenhouse was maintained by buffering of the soil temperature even with slight decreases in removal rates during the winter and extensive leaching of nutrients and contaminants was restricted with adjusting the water contents during the Korean rainy season. Although the tilling process was effective for biodegradation with aeration only, the simultaneous treatment due to apparent mixing of nutrients and microbes more favorably degraded the petroleum than the sequential treatment.

• 한국환경보건학회지
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• 제24권3호
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• pp.63-69
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• 1998

The treatment of soils and water contaminated with MTBE using the Fenton oxidation was investigated. The effects of dosage of $H_{2}O_{2}$, and Fe$^{2+}$ concentrations, and solution pH on transformation and mineralization in soil were evaluated. Generation of TBA and acetone following Fenton-oxidation of MTBE in water and generation of acetone following Fenton-oxidation of TBA were observed. Therefore TBA and acetone are degradation intermediates of MTBE. There was a large difference of treatment efficiency in Fenton oxidation of MTBE between soil and water system. This may be caused by the complex nature of soil, soil organic matter which can consumed OH $\cdot$ radicals, and interacting with inorganic-soil constituents. The pH of soil was observed to have a significant effect on the chemical oxidation efficient of MTBE in soil The data demonstrated that optimal pH range were pH 3~4 and around 6. The soil batch studies demonstrated that treatment efficiency of MTBE was enhanced by adding additional ferrous salts but Fenton-oxidation occurred in no additional iron which indicated that iron in soil can catalyze the Fenton-oxidation. The most effective parameter of Fentonoxidation was $H_{2}O_{2}$/Fe$^{2+}$ ratio which theocratical ratio is 0.5. The optimal range of this ratio was found to be 0.6~2.3. In evaluating effect of $H_{2}O_{2}$ dosage on treatment efficiency, the increase of $H_{2}O_{2}$ did not always lead to increase of decompositions of MTBE in soil. Fenton oxidation was effective in destroying MTBE in aqueous extracts of contaminated soil and water. Experimental data provided evidence that the Fenton oxidation can effectively remediate MTBE-contaminated water and soil.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권4호
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• pp.1-7
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• 2013

Subcritical water which acts as organic solvent with increasing temperature and pressure because dielectric constant and viscosity decrease can be used to remediate PAHs-contaminated soil. Factors influencing on extraction were studied with varying the water temperature $200{\sim}275^{\circ}C$, extraction time 0~90 min, flow rate 10~100 mL/min and pressure 3.9~10MPa. 300 g of soil sample which was contaminated with PAHs(naphthalene, phenanthrene, fluoranthene and pyrene; 423, 420, 539 and 428 mg/kg of initial concentration) was packed into the cell and placed to reactor and then the subcritical water was pumped through the cell for PAHs extraction. Naphthalene was removed almost 100% at relatively low temperature ($200^{\circ}C$). The removal rate of phenanthrene, fluoranthene, and pyrene increased by 8, 26, and 23% when the temperature increased from 200 to $275^{\circ}C$; and it was gradually increased as extraction time increased from 0 to 90 min. Decreasing removal rate when water flow rate increased from 10 to 30 mL/min, but there was no significant change after 30 mL/min. This is supposed due to channeling phenomenon. The pressure was not an effective factor for extraction of PAHs in this study. Based on the results, the importance of effective factor was in following sequence: temperature >> time > flow rate.

• 한국식품과학회지
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• 제19권6호
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• pp.543-549
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• 1987

식품에 수은이 오염(汚染)되었을 경우 수세(水沈) 및 조리(調理)중 수은함량에 어떠한 변화가 일어나는가를 알아보기 위해 수은 오염이 우려되는 쌀, 콩나물, 물고기가 사용되었으며 수은의 검출은 무염화(無炎火) 원자흡광법에 의해 측정되었다. 수은을 인위적으로 1ppm수준으로 오염시킨 쌀을 3회 수세시 전체 수은량의 24%가, 4회 수세시 31%가 감소되었으나 취반(炊飯)에 의해서는 유의적인 함량변화를 보이지 않았다. 수은 80ppm으로 오염된 콩나물을 3회 수세한 경우 수은잔류량의 약 26%가 감소하였으나 가열조리에 의해서는 전체 수은량의 감소가 없었다. 콩나물의 가열조리시 수은은 고형물에서 국물로 용출(溶出)되었으며 용출량은 가열시간, 소금농도와 첨가하는 물의 양에 따라 23-41%의 범위에서 다르게 나타났다. 수은 1ppm으로 오염된 물고기의 가열조리시 전체 수은량의 감소는 없었으나 이때 수은은 고형물에서 국물로 용출되었으며 용출량은 조리용수(調理用水)의 소금농도에 의해 2-10%의 범위에서 달리 나타났다. 물고기를 조리후 비가식부(非可食部)를 버리는 경우 오염(汚染)된 수은의 32%가 제거되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제9권3호
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• pp.1-11
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• 2004

매립지 침출수로 오염된 지반의 오염도 조사에 유전상수 측정기법의 적용성을 평가하기 위하여 매립지 침출수로 오염된 간극수를 포함한 사질토 지반의 유전특성을 분석하였다. 본 연구에서는 75kHz-12MHz 범위의 주파수에서 유전 상수를 실수부와 허수부로 구분하여 분석을 수행하였다. 유전상수 실수부는 공간전하분극과 배향분극의 발현정도에 영향을 받기 때문에 침출수 농도가 증가함에 따라 저주파 영역에서는 유전상수의 실수부 값이 증가하는 경향을 나타내었으나, 고주파 영역에서는 감소하는 경향을 나타내었다. 유전상수 허수부의 경우에는 측정 주파수에 관계없이 침출수의 농도가 증가함에 따라 전류전도에 의한 에너지 손실량이 증대되어 유전상수 허수부가 증가하는 경향을 나타내었다. 유전상수의 실수부와 허수부가 간극수 내 침출수 농도에 따라 변하는 것에 기초하여 유전상수 측정기법이 침출수로 오염된 지반의 오염도 평가에 효과적으로 적용될 수 있음을 확인하였다.