• Environmental Engineering Research
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• 제19권3호
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• pp.275-281
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• 2014

Aim of this study was to investigate biofilms attached in pipeline of water reuse from the MBR system treating sewage without chlorination in correlation to the outflow water quality. Two general pipe materials: polyvinyl chloride (PVC) and polyethylene (PE) were employed in the experiment. The peak growths were found at week 4 in both pipes. The maximum biofilms in PE pipe was $33mgVSS/cm^2$ with the growth rate of $4.75mgVSS/cm^2-d$ which was significant higher than that of PVC pipe. Biofilms examined by PCR-DGGE technique revealed five bacterial species in PE biofilms namely Sinorhizobium medicae WSM419, Sinorhizobium fredii NGR234, Geobacter sp. M18, Parachlamydia acanthamoebae UV-7, and Mycobacterium chubuense NBB4. The VSS concentrations in outflow had directly correlated to the biofilm attachment and detachment. High COD concentrations of outflow appeared during biofilm detaching phase. In summary, water quality of reuse water corresponded to the biofilms attachment and detachment in the pipeline.

• 상하수도학회지
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• 제23권6호
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• pp.763-768
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• 2009

Ozone is a strong oxidant and a powerful disinfectant. In general, it has been used in drinking water treatment during last 100years. Ozone dissolution features are defined by the two categories of ozone contactors, bubble-diffuser and sidestream ozone contactor. Currently, sidestream-injection systems are gaining in popularity but operating cost might be slightly higher. Sidestream ozone system dissolve ozone into a sidestream flow via an injection setup or in the main process flow stream in some sidestream arrangements. The sidestream flow is subsequently mixed with the main process flow stream, which is directed to a reation tank or pipeline for oxidation and disinfection reactions. The purpose of this study is to suggest optimal operating pressure, to figure out the static-mixer effect and to understand the microbubble characteristics of ozone to improve dissolution efficiency.

• 상하수도학회지
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• 제26권6호
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• pp.861-869
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• 2012

The chlorine's residual concentration prevents the regrowth of microorganism in water transport along the pipeline system. Precise prediction of chlorine concentration is important in determining disinfectant injection for the water distribution system. In this study, a pilot scale water distribution system was designed and fabricated to measure the temporal variation of chlorine concentration for three flow conditions (V = 0.88, 1.33, 1.95 m/s). Various kinetic models were applied to identify the relationship between hydraulic condition and chlorine decay. Genetic Algorithm (GA) was integrated into five kinetic models and time series of chlorine were used to calibrate parameters. Model fitness was compared by Root Mean Square Error (RMSE) between measurement and prediction. Limited first order model and Parallel first order showed good fitness for prediction of chlorine concentration.

• 상하수도학회지
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• 제32권2호
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• pp.115-122
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• 2018

Direct spring loaded pressure relief valve(DSLPRV) is a safety valve to relax surge pressure of the pipeline system. DSLPRV is one of widely used safety valves for its simplicity and efficiency. However, instability of the DSLPRV can caused by various reasons such as insufficient valve volume, natural vibration of the spring, etc. In order to improve reliability of DSLPRV, proper selection of design factors of DSLPRV is important. In this study, methodology for selecting design factors for DSLPRV was proposed. Dynamics of the DSLPRV disk was integrated into conventional 1D surge pressure analysis. Multi-objective genetic algorithm was also used to search optimum design factors for DSLPRV.

• 상하수도학회지
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• 제27권6호
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• pp.787-796
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• 2013

Sewer joint-related defect is one of the most common domestic sewer defects along with the lateral pipe problem. However, there are currently no criteria that precisely assess the joint-related sewer defects. Therefore, this study examined the joint-related sewer defects found in domestic circumstances, classified them according to the suggested defect code, and presented the examples of defect pictures. Each defect code was organized as the process of out of pipeline alignment (OPA) which shows the progress in deterioration. Each defect was classified into 5 grades depending on appropriate repair and rehabilitation method. The result of this study is expected to be useful for domestic CCTV inspectors to assess the sewer condition and helpful for managers to make a decision of repair and rehabilitation.

• 상하수도학회지
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• 제20권2호
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• pp.303-309
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• 2006

Yongdam reservoir located in Jeoliabuk-do has had a lot of concerns for its algal blooming since it has started to fill water. Many water utilities near Yongdam area use reservoirs even though they have some problems with certain algae that cause tastes and odors and clog filters. In this research, dissolved air flotation (DAF) technology was examined for feasibility for removal of algae. OAF can save the capital cost for its compactness, because its hydraulic loadings (overflow rates) are 10 times higher than sedimentation, and hydraulic detention times are much shorter, typically 5 to 15 minutes. As a result of this research, PAC is effective rather than Alum to DAF for pretreatment. Higher DOC plays an important role to change zetapotential negatively to inhibit destabilization of particle to coagulation. The length of pipeline to carry pressurized water into reactor does not affect reaction.

• 상하수도학회지
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• 제19권3호
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• pp.363-369
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• 2005

This paper presents the integrated technique of water quality analysis and Geographic Information System(GIS) for assessing the variation of free chlorine residuals by water temperature and supply distance in Sangri water supply system in Daegu. GIS was utilized for mapping projectmap, extraction of a pipeline route, and supply distance. Free chlorine residual is analyzed every month for appraising the seasonal variation. As a result, free chlorine residuals are affected both water temperature and water supply distance, and it becomes worse as water temperature and water supply distance is increased. To maintain 0.4mg/l of free chlorine residual, initial dose concentration should be over 1.85mg/l in summer.

• 한국축산시설환경학회지
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• 제14권3호
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• pp.149-158
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• 2008

본 시험은 젖소농가에서 보유하고 있는 여러가지 형태의 착유시스템에 대하여 계절별 세척수의 발생량과 이화학적 특성을 알아보고자 바켓식, 파이프라인식, 텐덤식, 헤링본식 등 착유시스템 유형별로 각각 3농가를 선정하여 계절별로 조사를 실시하였으며, 그 결과는 다음과 같다. 1. 착유시스템 유형별 세척수 발생량은 텐덤식과 헤링본식에서 많았으며 바켓식이 적었다 (P<0.05). 2. 착유작업별 세척수 발생량은 착유기 세척에 가장 많은 량의 세척수를 사용하였으며 여름철의 경우 텐덤식 $398.8{\ell}$, 헤링본식 $407.7{\ell}$가 다른 착유시스템보다 많은 세척수를 사용하였다 (p<0.05). 3. 착유과정에서 발생하는 세척수 발생량을 조사한 결과, 평균 $15.4{\ell}$/두였으며, 계절별로는 여름이 $16.4{\ell}$로 가장 많은 세척수가 발생되었다. 4. 착유과정에서 발생하는 세척수의 $BOD_5$는 착유실 세척시 발생하는 세척수가 $906.4mg/\ell$로 가장 높았으며, 유두 세척시 가장 낮은 $212.4mg/\ell$로 나타났다. COD, SS 등도 착유실 바닥세척시 가장 높은 경향을 보였다. 5. 세척수의 이화학적 특성은 pH는 $7.3{\sim}8.2$의 범위로 착유작업 단계에 따라 차이를 나타내었으며, 착유작업 후 착유실 외부로 흘러나오는 배출수의 $BOD_5$, COD, SS, T-N, T-P는 각각 731.2, 479.0, 751.6, 79.1, $14.7mg/\ell$였다. 이상의 시험결과를 종합해 보면 착유시스템 유형별 세척수 발생량은 바켓식, 파이프 라인식, 텐덤식 및 헤링본식이 각각 143.9, 487.9, 914.0, $856.7{\ell}$로 조사되었으며, 착유과정에서 발생하는 세척수량은 착유우 두당 $15.4{\ell}$로 착유시스템 유형 및 착유우 사육두수에 따라 낙농가도 농가실정에 맞는 세척수 처리시설 및 용량을 확보해야 할 것으로 판단된다.

• 한국지반신소재학회논문집
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• 제15권4호
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• pp.9-16
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• 2016

2004년 일본의 니가타켄 츄에츠 지방의 나가오카, 오지야시에서 1,450개 이상의 지하구조물이 1.5m까지 부상하였다. 융기손상은 Lifeline 시스템의 일부인 하수 시스템의 흐름뿐만 아니라 교통흐름을 방해로 인해 심각한 문제를 야기 시킨다. 복구작업의 경우 손상된 하수 시스템의 오픈 컷 조사는 나가오카시 정부에 의해 수행되었다. 지진으로 인한 매설된 파이프 라인의 손상에 대한 중요한 데이터는 조사결과로부터 수집하였다. 본 연구는 지하 구조물의 부상량에 영향을 미치는 요인을 SPT 시추공 logs를 통해 손상된 지역의 위치와 파이프라인의 경사를 포함하는 데이터를 사용하여 조사하였다. 지하구조물의 부상과 영향을 받는 지역의 지질학적 특성 사이의 상관관계 분석을 통해 부상현상의 주요변수는 지하수의 깊이, 원지반에서의 점토층 두께, SPT N값인 것으로 밝혔다.

• 상하수도학회지
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• 제30권3호
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• pp.253-261
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• 2016

A variety of methods for detecting the location of an underground water pipeline are being used across the world; the current main methods used in South Korea, however, have the problems of low precision and efficiency and the limitations in actual application. On this, this study developed locator capable of detecting the location of a water pipe by the use of an IMU sensor, and technology for using the extended karman filter to correct error in location detection and to plot the location on the coordinate system. This study carried out a tract test and a road test as basic experiments to measure the performance of the developed technology and equipment. As a result of the straight line, circular and ellipse track tests, the 1750 IMU sensor showed the average error of 0.08-0.11%; and thus it was found that the developed locator can detect a location precisely. As a result of the 859.6-m road test, it was found that the error was 0.31 m in case the moving rate of the sensor was 0.3-0.6 m/s; and thus it was judged that the equipment developed by this study can be applied to long-distance water pipes of over 1 km sufficiently. It is planned to evaluate its field applicability in the future through an actual pipe network pilot test, and it is expected that locator capable of detecting the location of a water pipe more precisely will be developed through research for the enhancement of accuracy in the algorithm of location detection.