The pressure sensor had been widely used to effectively monitor the flow status of the water distribution system for ensuring the reliable water supply to urban residents for providing the prompt response to potential issues such as burst and leakage. This study aims to present a method for evaluating the performance of pressure sensors in an existing water distribution system using transient data from a field pipeline system. The water distribution system in Y District, D Metropolitan City, was selected for this research. The pressure data was collected using low-accuracy pressure sensors, capturing two types of data: daily data with 1Hz and high-frequency recording data (200 Hz) according to specific transient events. The analysis of these data was grounded in the information theory, introducing entropy as a measure of the information content within the signal. This method makes it possible to evaluate the performance of pressure sensors, including identifying the most sensitive point from daily data and determining the possible errors in data collected from designated pressure sensors.

본 연구는 난방온실의 온도분포 균일화를 위한 기초자료 제공을 목적으로 온수난방 방식의 토마토 재배 온실 에서 난방실험을 통하여 난방배관의 표면온도와 실내기온 사이의 상관관계를 분석하고, 난방배관의 열전달특성 분석과 난방배관 배치의 개선을 통하여 난방배관 표면온도의 편차를 줄이고 균일도를 향상시키기 위한 방안을 도출하였다. 서로 다른 두 온실의 온도분포를 분석하여 최대편차와 균일도를 검토한 결과, 온수의 유량이 많고 난방배관의 길이가 짧게 배치된 온실의 온도편차가 작고, 균일도는 높은 것으로 나타났다. 또한 순환팬을 가동한 경우에 온도편차는 작아지고 균일도가 개선되는 것을 확 인할 수 있었다. 난방배관의 표면온도와 실내기온 사이의 상관관계를 분석한 결과, 두 온실 모두에서 유의적인 (p<0.01) 정적 상관관계가 있는 것으로 나타났다. 온수난방 온실에서 실내기온의 분포는 난방배관 표면온도의 분포에 영향을 받는다는 것을 확인할 수 있었고, 온도편차 가 최소화 되도록 난방배관을 배치함으로써 실내기온 분포의 균일도를 개선할 수 있는 것으로 판단되었다. 난방 배관의 열전달 특성을 분석한 결과 배관의 길이가 길어 지면 온도편차는 커지고, 관내의 유속이 빨라지면 온도 편차는 작아지는 것으로 나타났다. 따라서 지선배관의 길이가 짧아지도록 난방배관을 배치하고, 관내의 유속을 제어함으로써 온실의 온도분포와 환경의 균일성을 개선 할 수 있을 것으로 판단되었다. 국내 온실에서 가장 많 이 사용하고 있는 튜브레일(40A) 방식의 온수난방시스 템에서 하나의 지선배관에서의 온도편차를 3oC 이내로 조절하기 위해서는 관내의 유속이 0.2, 0.4, 0.6, 0.8, 1.0m·s-1일 때 난방배관의 길이는 각각 40, 80, 120, 160, 200m 이내로 제한해야 하는 것으로 분석되었다.

Waterworks facilities inevitably experience some amount of leakage even if there is a lot of investment or state-of-the-art technology that is applied such as DMA(District Metered Area) system construction, leakage detection, repair, pipe rehabilitation, etc. The primary reason is the leakage is naturally restored over time. In the UK, this restoration characteristic is defined as NRR(Natural rate of rise of leakage) and used to decision making for prioritizing active leakage control of DMAs. However, this restoration characteristic is well recognized, but researches on NRR in the water distribution system are insufficient in Korea. In this study, the estimation method of NRR was developed suitable for applicating in Korea considering of SCADA data, water infrastructure, and water usage patterns by modification of the UK's NRR method. The proposed method was applied to 9 DMAs and verified it's applicability by comparing with the other water loss performance indicators. It is expected that the proposed method can be used to support decision making for sustainable NRW(Nor-revenue water) management in the water distribution system.

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.

Maintaining adequate residual chlorine concentration is an important criteria to provide secure drinking water. The chlorine decay can be influenced by unstable flow due to the transient event caused by operation of hydraulic devices in the pipeline system. In order to understand the relationship between the transient event and the chlorine decay, the probability density function based on the water demand curve of a hypothetical water distribution system was used. The irregular transient events and the same number of events with regular interval were assumed and the fate of chlorine decay was compared. The chlorine decay was modeled using a generic chlorine decay model with optimized parameters to minimize the root mean square error between the experimental chlorine concentration and the simulated chlorine concentration using genetic algorithm. As a result, the chlorine decay can be determined through the number of transients regardless of the occurrence intervals.

Surge pressure is created by rapid change of flow rate due to operation of hydraulic component or accident of pipeline. Proper control of surge pressure in distribution system is important because it can damage pipeline and may have the potential to degrade water quality by pipe leakage due to surge pressure. Surge relief valve(SRV) is one of the most widely used devices and it is important to determine proper parameters for SRV’s installation and operation. In this research, determining optimum parameters affecting performance of the SRV were investigated. We proposed the methodology for finding combination of parameters for best performance of the SRV. Therefore, the objective function for evaluate fitness of candidate parameters and surge pressure simulation software was developed to validate proposed parameters for SRV. The developed software was integrated into genetic algorithm(GA) to find best combination of parameters.

This study attempts to draw factors for an analysis of the operation effect of a rechlorination facility and autodrain equipment for residual chlorine equalization by installing and operating a rechlorination facility and autodrain equipment in P City and analyzing the practical evaluation method and operation effect. For this purpose, this study selected three indicators for an analysis of the effectiveness of residual chlorine equalization and conducted a comparative analysis before and after the implementation of the residual chlorine equalization. As a result of estimation, ① the reduction of the residual chlorine concentration range from a water treatment plant to the pipe end was 16.0%; ② the total reduction of chlorination input was 18.0%; and ③ the reduction of the generation of disinfection by-products was 19.5%. In addition, this achieved enough residual chlorine equalization in the supply process and shows that it could successfully achieve the economic feasibility of investment in equipment and the reduction of the generation of disinfection by-products. Like this, it is judged that the three indicators suggested in this study will be used sufficiently as indicators of an analysis of the effectiveness of residual chlorine equalization according to the operations of the rechlorination facility and autodrain equipment.

In this study, determination methods of monitoring location in water distribution system were suggested and applied to real test bed. Small block of Gwangtan water distribution system is consisted of 582 pipes, 564 junctions, 1 reservoir, and 1 pump station. Small block of Ho Chi Minh water distribution system is consisted of 162 pipes, 148 junctions, and 1 reservoir. Two small block water distribution systems were analyzed by pressure contribution analysis method to determine the optimum monitoring locations. The pressure change was estimated at each junctions by the additional demand at a junction. From the results, the optimum monitoring location can be determined by rank of pressure contribution index at each junctions due to demand change at a junction.

It has been widely accepted that the pressure management of water distribution systems using pressure reducing valves(PRVs) would be an effective method for controlling leakages. A pressure reducing valve (PRV) regulates outlet pressure regardless of fluctuating flow and varying inlet pressure, thereby reducing leakage and mitigating the stress on the water distribution system. However, the operation of a PRV is vulnerable to its mechanical condition and hydraulic operability. In this research, the effect of PRVs installed in water distribution system are evaluated in terms of hydraulic pressure reduction and mechanical performance by analyzing measured pressure data with statistical approach. A statistical approach using the moving average filter and frequency analysis based on fourier transform is presented to detect abnormally operated PRVs that have been densely installed in water distribution system. The result shows that the proposed approach can be a good performance evaluation method by simply measuring pressures for the PRVs.

A CCTV inspection method has been widely used to assess sewer condition and performance, but Korea lacks a proper decision support system for prioritizing sewer repair and rehabilitation (R&R). The objective of this paper is to introduce the results that we have developed in the Sewer Condition Assessment and Rehabilitation Decision-making (SCARD) Program using MS-EXCEL. The SCARD-Program is based on a standardized defect score for sewer structural and hydraulic assessment. Priorities are ranked based on risk scores, which are calculated by multiplying the sewer severity scores by the environmental impacts. This program is composed of three parts, which are decision-making for sewer condition and performance assessment, decision-making for sewer R&R priority assessment, and decision-making for optimal budget allocation. The SCARD-Program is useful for decision-makers, as it enables them to assess the sewer condition and to prioritize sewer R&R within the limited annual budget. In the future, this program logic will applied to the GIS-based sewer asset management system in local governments.

When designing Water Distribution System (WDS), determination of life cycle for WDS needs to be preceded. And designer should conduct comprehensive design including maintenance and management strategies based on the determined life cycle. However, there are only a few studies carried out until now, and criteria to determine life cycle of WDS are insufficient. Therefore, methodology to determine life cycle of WDS is introduced in this study by using Life Cycle Energy Analysis (LCEA). LCEA adapts energy as an environmental impact criterion and calculates all required energy through the whole life cycle. The model is build up based on the LCEA methodology and model itself can simulate the aging and breakage of pipes through the target life cycle. In addition the hydraulic analysis program EPANET2.0 is linked to developed model to analyze hydraulic factors. Developed model is applied to two WDSs which are A WDS and B WDS. Model runs for 1yr to maximum 100yr target life cycle for both WDSs to check the energy tendency as well as to determine optimal life cycle. Results show that 40yr and 54yr as optimal life cycle for each WDS, and tendency shows the effective energy is keep changing according to the target life cycle. Introduced methodology is expected to use as an alternative option for determining life cycle of WDS.

The flushing is important to maintain good water quality in water main. It is a technique of using water velocity to remove sediments in water distribution system. The variety of water quality problems can occur in a distribution system, so too can a variety of benefits be gained by system flushing. In order to effectively perform the flushing, the contaminants to be removed to set up and it can be solved, it is necessary to ensure the proper flow rate. In this study, the removal of contaminants present in the inner water pipe attached loose deposits such as fine particles of granular activated carbon, sand and iron corrosion product sought to derive flow rates. Thus, the constant observation of using pilot plant scale water distribution plant for the movement of floating characteristics of particles were assessed.

In this paper we have studied the effect of water droplet size on nano-particle size distribution using SMPS(Scanning Mobility Particle Sizer)system. It can be seen that the unknown peak at >100 nm was caused by water droplets which did not dry completely when DI water was used as a solvent in the SMPS system. Therefore, it is important to dry water droplets generated from atomizer in the SMPS system when measuring the particle size distribution using less than 100 nm nano-particles in diameter. From this study, It can be concluded that the napion was a useful material as dryer ones and using EAG(Electro Aerosol Generator) as a particle generator was the most effective in reducing the effect of water droplets.

상수관망시스템의 운영목적은 탄력성을 높여 각종 비정상상황에 유연하게 대처할 수 있는 방향으로 점차 변화하고 있으며 이에 따라 비정상상황에 따른 단수구역 발생에 대한 사후대책 대비를 통한 탄력성 향상이 필수적이다. 이를 위한 가장 효율적인 방법은 수계전환에 따른 비상공급 수원 확보이며, 비상관로를 통하여 인접 배수블록으로부터 단수된 구역에 용수를 공급할 수 있다. 성공적인 비상연계 운영을 위해서는, 수리학적 해석을 통하여 시공간적인 측면에서의 공급성능을 평가해야 한다. 비상연계 시, 공간적인 범위를 결정하는 주요 요소는 관경, 위치 및 관저고와 같은 비상관로에 해당하는 제원이며, 시간적인 범위를 결정하는 주요 요소는 연계배수지의 용량과 정수장에 공급 가능한 추가수량이다. 본 연구에서는 A 시의 상수관망에 대하여 배수지 1지에 문제가 발생하여 타 배수지들로부터 비상연계를 받는 시나리오에 대하여 모의를 진행하였다. 배수지의 저류량 및 유입량에 대한 모의를 위하여 Advanced-Pressure Driven Analysis 모형을 사용하였으며, 수리해석 결과를 바탕으로 공급범위기준지표 및 공급시간기준지표를 산정하여 연계공급성능에 대한 다각도적인 평가를 진행하였다. 이에 비상연계에 대하여 소비자들이 실제 체감하는 공급성능을 시공간적인 측면에서 파악할 수 있었으며, 설계제원의 타당성에 대한 검토가 가능하였다. 이는 비상연계 성능향상을 위한 구조적 대책 및 비구조적 대책 수립에 대한 의사결정에 용이하게 활용될 수 있을 것으로 기대한다.

상수도관의 파열은 과도한 압력, 노후화, 온도변화나 지진 등에 의한 지반이동에 의해 발생한다. 상수도관 파열이 대규모 단수, 싱크홀 등과 같은 더 심각한 피해 이어지지 않도록 신속하게 탐지 및 대응하는 것이 중요하다. 본 연구에서는 상수도관 파열 탐지를 위해 개선 Western Electric Company (WECO) 방법을 개발하였다. 개선 WECO 방법은 통계적공정관리기법 중 하나인 기존 WECO 방법에 임계치 조정자(w)를 추가하여 대상 네트워크에 적합한 이상탐지 의사결정을 할 수 있도록 했다. 개발된 개선 WECO 방법을 미국 텍사스 오스틴 관망에 적용 및 검증하였다. 상수도관 파열 발생 시 측정한 비정상데이터와 수요량 변동만 고려한 정상데이터를 이용하여 기존 및 개선 WECO 방법을 비교하였다. 최적 임계치 조정자 w값을 결정하기 위해 민감도 분석을 수행하였으며, 다양한 계측시간 간격 데이터(dt = 5, 10, 15분 등)의 영향도 분석하였다. 각 경우 별 탐지 성능은 탐지확률, 오경보확률, 평균탐지시간을 계산하여 비교하였다. 본 연구에서는 도출된 결과를 바탕으로 WECO 방법을 실제 상수도관 파열 탐지에 적용하기 위한 가이드라인을 제공한다.

본 연구에서는 상수관망의 최적 수압모니터링 지점선정 알고리즘과 역추적 계산법을 이용한 누수탐지 알고리즘을 개발하였고 파일럿 플랜트에서 실험을 통해 검증하였다. 먼저 누수탐지를 위한 최적의 모니터링 지점선정을 선정하고 압력계를 설치하여 누수로 인한 압력변위를 측정하였다. 누수탐지를 위한 역추적계산법의 검증을 위하여 누수탐지를 수행하였고 파일럿플랜트에서 실제 재현된 누수의 지점과 누수량을 정확하게 산정하였다. 누수량을 0.0005 m3/s로부터 0.0018 m3/s까지 변화시키며 누수를 재현하였고 누수지점에 근접한 장소를 찾는데 성공하였다. 본 연구에 서는 실험을 통해서 누수탐지기법으로 사용된 역추적계산법이 유효함을 검증할 수 있었다.

The tap water is generally known to be corrosive in the pH range at 6.5 ~ 7.5. And the degree of corrosion varies depending on the types of raw water such as river surface water or lake water of the dam. Although several corrosion index represents the corrosivity of tap water, the typical corrosion indexes such as Langelier saturation index (LI) and calcium carbonate precipitation potential (CCPP) were calculated to monitoring the corrosive water quality about raw and tap water in water distribution system. To control the corrosive water quality, the correlation between corrosion index and water quality factors were examined. In this study, corrosion index (LI, CCPP) and the pH was found to be most highly correlated.