• 한국물환경학회지
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• 제29권5호
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• pp.598-609
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• 2013

Spatial and temporal distribution of environmental factors and epilithic diatom communities in major rivers (30 rivers and 58 sampling points) of the Korean peninsula were surveyed each one time before (May) and after the monsoon (October) 2012. The stream of the east harbor (EAST), the south harbor (SOUTH), and the west harbor (WEST) was sampled in order. Over the survey, a total of 284 taxa were classified, and the number of diatom species in each harbor did not show significant changes after the monsoon, but a biomass significantly decreased. Results also showed that EAST deterioration of water quality and chlorophyll-a after the monsoon, was opposite to SOUTH. Five major dominant species including Nitzschia inconspicua, which contained higher biomass over the survey, were common species which widely distributed in brackish water. Indicator Species Analysis showed that a large number of clean water species in EAST and polluted water species in SOUTH and WEST were emerged respectively. In sum, the Asian monsoon significantly decreased a biomass of epilithic diatoms and water qualities over the harbors (lower stream) in the Korean peninsula, but did not change the major species indicating water quality.

• 환경위생공학
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• 제9권1호
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• pp.17-28
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• 1994

There are many possibilities that may lead to low quality of drinking water Recently, some unknown deposits in tap water raised a lot of public concern regarding the safety of drinking water in Seoul. We analyzed the quality of tap water from several areas of Seoul, including the area where public complaints about tap water were high. The results shows that the quality of tap water in Seoul was good, well below the environmental standards. Only the tap water from the area with high public complaints showed turbidity higher than that of other area. Also, result shows that component of deposit in tap water was Al, Fe, Mn, and Zn. Based on the research result we propose several measures that might help to reduce the amount of deposit in tap water as follows : 1 Using coagulant aid when coagulating or adjusting pH when filtering. 2. Replacing old water pipeline with new corrosive- resistant one. 3. Increasing water treatment efficiency by enhancing water treatment system such as automation of water treatment system adjusting production capacity, and improving operational condition of filler basin. 4. Chlorine disinfection at the distribution reservoir would help maintaining the same pH level and chlorine concentration throughout the water pipeline and reduce corrosion of pipe.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.162-162
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• 2019

Water Distribution Network (WDN) is a critical infrastructure to be maintained ensuring proper water supply to wide-spread consumers. The WDN consists of pipes, valves, pumps and tanks, and these elements interact each other to provide adequate system performance. If elements fail by internal or external interruptions, it may result in adverse impact to water service with different degree depending on the failed element. To determine an appropriate maintenance priority, the critical elements need to be identified and mapped in the network. In order to identify and prioritize the critical elements in WDN, an element-based simulation approach is proposed, in which all the elements composing the WDN are reviewed one at a time. The element-based criticality is measured using several resilience indexes that are newly developed in this study. The proposed resilience indexes are used to quantify the impacts of element failure to water service degradation. Here, three resilience indexes are developed, such as User Demand Severity, Economic Value Loss and Water Age Degradation, each of which intends to measure different aspects of consequences, such as social, economic, and water quality, respectively. For demonstration, the proposed approach is applied to a benchmark water network to identify and prioritize the critical elements.

• 상하수도학회지
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• 제19권4호
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• pp.487-496
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• 2005

Chlorine bulk decay tests were carried out by bottle test under controlled conditions in a laboratory. Experiments were performed at different temperatures: $5^{\circ}C$, $15^{\circ}C$, $25^{\circ}C$, and the water temperatures when samples were taken from the effluent just before entering to its distribution system. 38 bulk tests were performed for water of Al (water treatment plant), 4 bulk tests for A2 (large service reservoir), and A3(pumping station). Residual chlorine concentrations in the amber bottles were measured over time till about 100 hours and bulk decay coefficients were evaluated by assuming first-order, parallel first-order, second-order. and $n^{th}-order$ reaction. The $n^{th}-order$ coefficients were obtained using Fourth-order Runge-Kutta Method. A good-fit by the average coefficient of determination ($R^2$) was first-order ($R^2=0.90$) < parallel first-order ($R^2{_{fast}}=0.92$, $R^2{_{slow}}=0.95$) < second-order ($R^2=0.95$) < $n^{th}-order$ ($R^2=0.99$). But if fast reaction of parallel first-order bulk decay were applied to the effluent of large service reservoir with ca. 20 hours of travel time and slow reaction in the water distribution system following the first 20 hours, parallel first-order bulk decay would be best and easy for application of water quality modeling technique.

• 한국물환경학회지
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• 제32권6호
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• pp.520-527
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• 2016

Phycocyanin (PC) is one of the water-soluble accessory pigments of cyanobacteria species, and its concentration is used to estimate the presence and relative abundance of cyanobacteria. In laboratory experiments, PC content of field data were determined using Sarada's freeze-thaw method in algal bloom season. The effectiveness of three selected extraction methods (repeated freeze-thaw method, homogenization, power control) for PC were determined. The extraction efficiency of phycocyanin was the highest (of the methods compared) when a single freezing-thawing cycle was followed by pre-sonication. Applying this optimized method to surface water of Korean inland waters, the average concentration distribution was estimated at $2.9{\sim}51.9mg/m^3$. It has been shown that the optimized pre-sonication method is suitable to measure cyanobacteria PC content for the characterization of inland waters. The approach and results of this study indicates the potential of effective methods for remote monitoring and management of water quality in turbid inland waters using hyperspectral remote sensing.

• 해양환경안전학회지
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• 제15권4호
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• pp.315-328
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• 2009

1997년부터 2008년까지 12년 동안 가로림연안 수질환경의 특성과 장기변동 경향을 조사하였다. 3개 조사정점에서 수층(표층, 저층)별 및 계절별로 년 4회 수온, 염분, 부유물질, 화학적산소요구량, 용존산소, 영양염류, 클로로필 a에 대해 조사한 결과, 표층수와 저층수 간에 수온을 제외한 진조사항목에서 표 저층간의 차이가 없었다. 공간적 분포특성은 모든 조사항목에서 정점간 유의적인 차이가 없어 가로림만 중간부터 외측으로 원활한 해수교환이 이루어지고 있었다. 계절별로는 수소이온농도와 암모니아질소을 제외한 조사 항목에서는 유의성이 입증되었고, 정점별로 대체로 비슷한 변화폭을 나타내었다. 12년 동안 수질의 장기 변동은 네 그룹으로 구분되어 항목에 따라 부분적으로 차이가 있으나 전반적 장기 변동을 조사한 결과 근래에 들어 염분은 높아진 반면, 용존무기질소, 질산질소 및 화학적산소요구량 등이 감소하고 있어 담수의 유입이 거의 없는 대체로 양호한 수질상태를 유지하고 있으며 수산학적으로 매우 중요한 연안으로 앞으로 지속적인 보전이 요구된다.

• 한국막학회:학술대회논문집
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• 한국막학회 1997년도 심포지움시리즈 Jan-97 수처리용 분리막 기술 및 응용
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• pp.111-130
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• 1997

The lack of water resources is becoming worse due to water pollution with accelerated industrialzation and regional unbalanced distribution of water resources. In recent, the production water quality is decreasing because of the increased organic matters and soluble solids in the water sources for power plants. The purpose of this paper discribes the ststus and prospect of membrane application in electric power industry. So this study lies in developing a process which can produce high purity water by appluing RO(Reserve Osmosis) ahead of the IX(Ion Exchange) tower and evaluating the product water quality and the cost effectiveness. The capital and operating cost for the treatment of brackish water, sea water by RO were presented as a reference for the review on securing water source for the new plant site.

• 해양환경안전학회지
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• 제15권4호
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• pp.297-313
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• 2009

1972년부터 2006년까지 30년 동안 군산연안 수질환경의 특성과 장기변동 경향을 조사하였다. 6개 정점에서 수층(표층과 저층)별 계절별로 년 4회 수온, 염분, 부유물질, 화학적산소요구량, 용존산소, 영양염류에 대해 조사한 결과, 표층수와 저층수 간에는 화학적산소요구량 및 인산인을 제외한 모든 조사항목에서 표 저층 간의 차이가 컸었다. 공간적 분포특성은 수온과 용존산소 및 부유물질은 정점 간 차이가 없었으나, 그 외 조사항목에서는 정점 간 차이가 컸으며 주성분 분석결과 금강 하구역인 정점 1과 중간해역인 정점 2-4 및 비교적 외해측인 정점 5-6의 세 그룹으로 구분되었다. 계절별로는 화학적산소요구량과 부유물질을 제외한 조사 항목에서는 유의성이 입증되었고, 정점별로 차이가 있어 내측은 계절에 따른 변화가 큰 상태이었고 외해측으로 갈수록 변화폭이 줄어드는 경향이었다. 24년 동안 수질의 장기 변동은 표층 네 그룹, 저층 다섯 그룹으로 구분되어 항목에 따라 부분적으로 차이기 있었으나 전반적으로 염분, 수소이온농도 및 용존산소는 점차 증가하는 경향이었고 화학적산소요구량은 불규칙한 변곡선 형태이며, 영양염류는 증가하는 경향으로 근래에 약간 안정화되었다가 2006년에 다시 약간 증가하는 특징을 보여 경인연안, 아산연안 및 천수만과 마찬가지로 육수 유입의 원인에 기인한 것으로 사료된다.

• 한국대기환경학회지
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• 제4권2호
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• pp.57-66
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• 1988

Sandy dust phenomena was observed from April 19 to 23, 1988 in Seoul and suspended particulate was collected by Andersen air sampler during this period. The samples were analyzed for 16 components $(SO_n^{2-}, NO_3^-, Cl^-, PO_4^{3-}, NH_4^+, F^-, Al, Fe, K, Cu, Mn, Na, Pb, Mg, Ca, Cd)$. The conclusions are as follwes: 1. Total suspended particulate concentation during the period of sandy dust phenomena was 489 $\mug/m^3$ (ordinary times: 140-125 $mug/m^3$) 2. The water - soluble ion component concentration of suspended particulate during the period of sandy dust phenomena was few and the metal concentration of that was more than that of ordinary times. 3. The cumulative frequency distribution of suspended particulates in logarithmic diagram did not show similar to normal log distribution during the period of sandy dust phenomena. 4. $SO_4^{2-}, NO_3^-, Cl^-, and PO_4^{3-}$ was onsided to coarse particle, and $NH_4^+$ and F to fine particle in the size distribution of water - soluble ion components during the period of sandy dust phenomena. 5. Metal concentration was high and Al, Fe, Cu, Mn, Na, Mg, and Ca was onsided to coarse particle, and K, Pb, and Cd to fine particle in the size distribution of metal components. 6. During the period of sandy dust phenomena the quantity of respirable particle (< 1 $\mum$) was about 3 times and that of metal components were about 2 - 11 times than that of ordinary times. 7. The concentrations of $NO_3^-, Cl^-, NH_4^+$ at ordinary times were 1.1 - 4 time than that of the period of sandy dust phenomena.

• Journal of Advanced Marine Engineering and Technology
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• 제28권8호
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• pp.1195-1202
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• 2004

In this paper an experimental study was investigated for two-phase flow distribution in compact heat exchanger header. A test section was consisted of the horizontal bottom dividing header($\phi$: 5 mm, L: 80 mm) and 10 upward circular mini channels ($\phi$: 1.5 mm, L: 850 mm) using an acrylic tube. Three different types of tube intrusion depth were tested for the mass flux and inlet mass quality ranges of 50 - 200 kg/$m^2$s and 0.1 - 0.3, respectively. Air and water were used as the test fluids. The distribution of vapor and liquid is obtained by measurement of the total mass flow rate and the calculation of the quality. Two-phase flow pattern was observed, and pressure drop of each channel was measured. By adjusting the intrusion depth of each channel an uniform liquid flow distribution through the each channel was able to solve the mal-distribution problem.