• 한국재난정보학회 논문집
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• 제16권1호
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• pp.144-154
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• 2020

연구목적: 본 논문은 밸브의 누수 상태를 확인하기 위한 모니터링 시스템을 위하여 개발된 스마트 볼트의 적용성에 대한 기초 연구이다. 연구방법: 스마트 볼트에 내장된 변형률 센서와 가속도 센서를 이용하여 모의 누수 탐지 실험을 실시하였다. 연구결과: 스마트 볼트는 볼트 조임토크 기준에 부합하였으며 허용인장응력 범위 내에서 거동을 하여 상수도 체결부 적용에 부합되는 것으로 나타났다. 그리고 모의 누수 실험결과 밸브 누수 지점에선 60Hz 대역의 누수 신호가 탐지 되었으며, 메인관 누수에서는 상대적으로 고주파수 대역의 누수 신호도 탐지되었다. 결론: 모의 배관이 구속되지 않은 상태에서 전체적으로 연성진동이 이뤄진 것으로 보인다. 스마트 볼트를 통해 밸브 누수 신호의 감지에 대한 가능성을 확인하였다.

• 대한전자공학회논문지SP
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• 제48권3호
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• pp.125-131
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• 2011

상수도 누수 탐지 시스템은 상수관로상의 누수 발생을 탐지하고 누수 위치를 추정하여 그 결과를 관제 서버로 알리는 시스템이다. 기존의 누수 탐지는 일반적으로 사용자가 직접 장비를 들고 이동하면서 누수 발생 탐지를 하는 방식으로 진행하기 때문에 작업 속도도 느리고 작업자의 경험에 많은 부분을 의존해야 한다. 또한 누수 탐지의 정확도를 높이기 위해서는 물 사용이 적은 심야시간에 탐지를 해야 하기 때문에 작업에 어려움이 따른다. 본 논문에서는 센서네트워크를 이용한 무선 누수 탐지 시스템을 제안하였다. 제안된 시스템에서 각 누수 탐지 장치는 무선 네트워크를 형성하여 탐지 결과를 주고받으며 이를 통하여 탐지의 신뢰성을 높였다. 또한 정확한 탐지를 위하여 상수도관의 수중음의 특성을 분석하고 누수음을 분리해내는 사전 신호처리 과정을 제안하였다. 마지막으로 누수 위치를 추정하기 위해서는 두 지점에 설치된 누수 탐지 장치의 시간 동기가 매우 중요한데 본 논문에서는 GPS에서 제공하는 1PPS(1 Pulse Per Second) 신호를 이용하여 정확한 시간 동기를 획득하였다. 본 시스템은 남양주시의 상수관로상에 적용하여 그 성능을 검증하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.276-276
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• 2018

In this paper the potential of the Principle Component Analysis(PCA) technique that can be used to detect leaks in water pipe network blocks was evaluated. For this purpose the PCA was conducted to evaluate the relevance of the calculated outliers of a PCA model utilizing the recorded pipe flows and the recorded pipe leak incidents of a case study water distribution system. The PCA technique was enhanced by applying the computational algorithms developed in this study. The algorithms were designed to extract a partial set of flow data from the original 24 hour flow data so that the variability of the flows in the determined partial data set are minimal. The relevance of the calculated outliers of a PCA model and the recorded pipe leak incidents was analyzed. The results showed that the effectiveness of detecting leaks may improve by applying the developed algorithm. However, the analysis suggested that further development on the algorithm is needed to enhance the applicability of the PCA in detecting leaks in real-world water pipe networks.

• 상하수도학회지
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• 제33권2호
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• pp.159-167
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• 2019

In this paper the potential of the principal component analysis(PCA) technique for the application of detecting leaks in water pipe networks was evaluated. For this purpose the PCA was conducted to evaluate the relevance of the calculated outliers of a PCA model utilizing the recorded pipe flows and the recorded pipe leak incidents of a case study water distribution system. The PCA technique was enhanced by applying the computational algorithms developed in this study which were designed to extract a partial set of flow data from the original 24 hour flow data so that the effective outlier detection rate was maximized. The relevance of the calculated outliers of a PCA model and the recorded pipe leak incidents was analyzed. The developed algorithm may be applied in determining further leak detection field work for water distribution blocks that have more than 70% of the effective outlier detection rate. However, the analysis suggested that further development on the algorithm is needed to enhance the applicability of the PCA in detecting leaks by considering series of leak reports happening in a relatively short period.

• 상하수도학회지
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• 제35권1호
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• pp.15-25
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• 2021

In this study, a method of leakage detection was proposed to locate leak position for a reservoir pipeline valve system using wavelet coherence analysis for an injected pressure wave. An unsteady flow analyzer handled nonlinear valve maneuver and corresponding experimental result were compared. Time series of pressure head were analyzed through wavelet coherence analysis both for no leak and leak conditions. The leak information can be obtained through either time domain reflectometry or the difference in wavelet coherence level, which provide predictions in terms of leak location. The reconstructed pressure signal facilitates the identification of leak presence comparing with existing wavelet coherence analysis.

• 상하수도학회지
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• 제31권5호
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• pp.459-469
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• 2017

A real scale leakage test facility was developed to study the leak signal characteristics of water supply pipelines, and then leak tests were carried out. The facility was designed to overcome the limited experimental circumstances of domestic water supply pipeline experimental facilities. The length of the pipeline, which was installed as a straight line, is 280m. Six pipes were installed on a 70m interval with different pipe material and diameters that are DCIP(D200, D150, D100, D80), PE(D75) and PVC(D75).The intensity of the leakage is adjusted by changing the size of the leak hole and the opening rate of ball valve. Various pressure conditions were simulated using a pressure reducing valve.To minimize external noise sources which, deteriorate the quality of measured leak signal, the facility was built at a quiet area, where traffic and water consumption by customers is relatively rare. In addition, the usage of electric equipment was minimized to block out noise and the facility was operated using manual mode. From the experimental results of measured leakage signal at the facility, it was found that the signal intensity weakened and the signal of high frequency band attenuated as the distance from the water leakage point increased.

• Corrosion Science and Technology
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• 제3권6호
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• pp.233-239
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• 2004

Primary water stress corrosion cracking of steam generator tubings occur on many tubes in pressurized water reactors(PWRs), and they are repaired using sleeves or plugs. In order to develop proper repair criteria, it is necessary to know the leak behavior of the tubes, which have stress corrosion cracks. Crack development tests were carried out on the tubes at room temperature, and leak rate and burst pressure were measured on the degraded tubes at room temperature and a high temperature. No leakage was detected on the tubes where 100 % through wall crack developed, at 1560 psi, which is an operating pressure difference of pressurized water reactors(PWRs). In some tests, leak rates of the tubes increased with time at a constant internal water pressure. A test tube showed a very small amount of leakage at 2700 psi in a high temperature pressure test at $282^{\circ}C$, but it disappeared after the pressure increased slightly. Even cracks are 100 % through wall, they need to open in order to reach a certain amount of leak rate at the operating pressure difference.

• Nuclear Engineering and Technology
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• 제33권4호
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• pp.423-440
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• 2001

For sodium cooling liquid metal reactors during the last 25 years, it was most important to verify the safety of the steam generator, which absolutely requires a water leak detection system with fine sensitivity and response. This study describes the structure and leak classification of the HAMMER (Korea Advanced Liquid Metal Reactor) steam generator, compared with other classifications, and explains the effects of leak development. The requirements and experimental situations for the development of the KALIMER acoustic leak detection system (KADS) which detects micro leaks, not intermediate leaks, are introduced. We proposed four frequency bands, 1∼8kHz, 8∼20kHz, 20∼40kHz and 40∼200kHz, split effectively for analyzing the detected acoustic leak signals obtained from the sodium-water reaction model or water model in the mock-up system.

• 비파괴검사학회지
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• 제35권1호
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• pp.31-38
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• 2015

스마트 워터 그리드와 같은 지하매설 상수도 배관망을 구성할 때 누수 지점에 대한 지능적 탐지는 중요한 요소이다. 이런 지능형 배관망의 구성에는 많은 수의 누수탐지센서를 일정한 간격으로 설치하는 것이 필요하며 이들 센서에서 계측되는 신호를 분석해서 누수 유무 및 누수발생시 그 지점의 추정을 신속히 할 수 있어야 한다. 그래서 본 연구에서는 특히 두 지점에서 동시에 누수가 발생하는 경우에 대해 그 센서가 측정한 신호가 가지는 특성 및 두 누수지점 동시 추정 가능성을 심도있게 분석하였다. 즉, 센서간 거리가 315.6 m 인 100A 사이즈의 주철관 상수도 배관에 대해 두 지점 동시 누수시 각각의 개별 센서신호를 계측하였으며, 그 신호를 기반으로 주파수 특성 및 상호상관함수 등의 분석을 통해 두 지점의 누수탐지에 대해 기술하였다.

• 한국정밀공학회지
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• 제23권11호
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• pp.50-57
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• 2006

The water leak in water-cooled generator stator windings can generate the serious accidents such as insulation breakdown and it brings a generator to the unexpected sudden outage. Accordingly, it is important to diagnose the water absorption of them for the effective operation of power plant. Especially, the capacitance value which is measured for diagnosis is very small so the special diagnosis methods like stochastic theory are needed. KEPRI developed the water absorption test equipment and diagnosis technology for them. The developed diagnosis technology is applied to the real system and the results of water absorption test for stator windings are agreed to them of water leak test.