Experimental Study on Leak-induced Vibration in Water Pipelines Using Fiber Bragg Grating Sensors

김대길,이아람,박시웅,여찬일,배철호,박형준 한국광학회 2022 Current Optics and Photonics Vol.6 No.2

Leak detection is one of the most important challenges in condition monitoring of water pipelines. Fiber Bragg grating (FBG) sensors offer an attractive technique to detect leak signals. In this paper, leak measurements were conducted on a water distribution pilot plant with a length of 270 m and a diameter of 100 mm. FBG sensors were installed on the pipeline surface and used to detect leak vibration signals. The leak was demonstrated with 1-, 2-, 3-, and 4-mm diameter leak holes in four different pipe types. The frequency response of leak signals was analyzed by fast Fourier transform analysis in real time. In the experiment, the frequency range of leak signals was approximately 340–440 Hz. The frequency shifts of leak signals according to the pipe type and the size of the leak hole were demonstrated at a pressure of 1.8 bar and a flow rate of 25.51 m 3 /h. Results show that frequency shifts detected by FBG sensors can be used to detect leaks in pipelines.

음향방출 및 가속도 신호를 이용한 지하매설 상수도배관의 누수지점 탐지연구

이영섭,윤동진,정중채 한국비파괴검사학회 2003 한국비파괴검사학회지 Vol.23 No.3

지하매설 상수도 배관의 누수는 사회적, 환경적 그리고 경제적 문제를 야기시킨다. 이러한 누수에 대한 적절한 대응책의 하나로서 배관의 누수지점에 대한 탐지 및 수리가 해당될 것이다. 누수음은 배관의 누수지점의 식별에 좋은 탐지원이다. 비록 청음봉, 층음기 또는 지상마이크로폰과 같은 누수음으로 누수지점을 탐지하는 몇가지의 방법이 있어 왔지만, 그들은 그렇게 효율적인 도구들은 아니었다. 본 논문에서는, 좀 더 쉽고 효율적인 방법을 제공할수도 있는 음향방출센서와 가속도계를 사용한 누수위치탐지를 다룬다. 누수지점 탐지를 위해 센서로 부터의 입력신호에 대한 필터링, 신호처리 및 알고리듬을 기술하였다. 120 미터 길이의 배관이 실험을 위해 설치가 되었고, 실험결과들은 음향방출센서와 가속도계가 누수지점의 정밀탐지에 이용될 수 있음을 보여 주었다. 누수지점의 탐지에 극히 중요한 지하매설배관 속의 유체의 음파 전파속도에 관한 이론적 해석 또한 기술되었다. Leaks in underground pipelines can cause social, environmental and economical problems. One of relevant countermeasures against leaks is to find and repair of leak points of the pipes. Leak noise is a good source to identify the location of leak points of the pipelines. Although there have been several methods to detect the leak location with leak noise, such as listening rods, hydrophones or ground microphones, they have not been so efficient tools. In this paper, acoustic emission(AE) sensors and accelermeters are used to detect leak locations which could provide an easier and more efficient method. Filtering, signal processing and algorithm of raw input data from sensors for the detection of leak location are described. A 120 m-long pipeline system for experiment is installed and the results with the system show that the algorithm with the AE sensors and accelerometers offers accurate pinpointing of leaks. Theoretical analysis of sound wave propagation speed of water in underground pipes, which is critically important in leak locating, is also described.

LTE-M1 센서를 이용한 상수도관 누수감지 신호 특성 연구

오병근 ( Oh Byoung Geun ) 한국수처리학회 2021 한국수처리학회지 Vol.29 No.4

In this study, the frequency and shape characteristics of the sounds of leaks in water pipes were analyzed using an LTE-M1 sensor. We verified the relevance through frequency analysis and cross correlation analysis of the leakage signals for metal(STS) pipes and PE pipes. By processing the leakage signal detected by the sensor to determine the frequency bandwidth from 0 ~ 5120 Hz, it was found that the leak signal is strongest in the range of 200 ~ 400 Hz. Therefore, the specific frequency range of the leak sound was confirmed from 200 to 400 Hz. The intensity was attenuated with increasing distance from the leakage point. When comparing to the metal pipe and the PE pipe, the range of the frequency did not differ much, but the intensity of the frequency signal in the metal pipe was relatively high. The leak-detecting frequency band in which the leak occurs in pipes indicated that the strength of the leak signal weakens as it moves away from the leak point. These studies can be used as basic data to analyze the frequency characteristics of leaks and apply them to future technologies such as artificial intelligence, big data, IoT, and 5G to find leak points.

Research on Rapid Detection Method of Pipeline Leakage Based on The Transient Flow Method

You Fu,Biao Chen 한국유체기계학회 2023 International journal of fluid machinery and syste Vol.16 No.2

This paper presents a numerical simulation of a leaking pipeline and verifies the method's applicability using existing experimental data. The method involves generating reflected waves at the leak point by using pressure waves generated by fast valve closure, which causes aberrations in the pressure signal at the valve. The different times of aberration at different leak locations can be used to determine the location of the leak. Furthermore, the time domain information of the pressure signal is refined using the wavelet transform method to capture sudden changes in the pressure signal, which improves the accuracy of the leakage position. This method was tested for different leak locations, sizes, and pipeline wave speed conditions, resulting in accurate detection with an error of less than 1%. When there are multiple leak locations in the pipeline system, the method has a high degree of recognition of the existence of multiple leak locations and can accurately detect the location of each leak. Additionally, the effect of different valve closing times on the pressure waveform of pipeline leaks was studied, demonstrating that slow valve closure can detect the occurrence of a leak in the pipeline, while fast valve closure can be used to locate the leak.

KAL: kernel-assisted non-invasive memory leak tolerance with a general-purpose memory allocator

Jeong, Jinkyu,Seo, Euiseong,Choi, Jeonghwan,Kim, Hwanju,Jo, Heeseung,Lee, Joonwon John Wiley Sons, Ltd. 2010 SOFTWARE-PRACTICE & EXPERIENCE Vol.40 No.8

<P>Memory leaks are a continuing problem in the software developed with programming languages, such as C and C++. A recent approach adopted by some researchers is to tolerate leaks in the software application and to reclaim the leaked memory by use of specially constructed memory allocation routines. However, such routines replace the usual general-purpose memory allocator and tend to be less efficient in speed and in memory utilization. We propose a new scheme which coexists with the existing memory allocation routines and which reclaims memory leaks. Our scheme identifies and reclaims leaked memory at the kernel level. There are some major advantages to our approach: (1) the application software does not need to be modified; (2) the application does not need to be suspended while leaked memory is reclaimed; (3) a remote host can be used to identify the leaked memory, thus minimizing impact on the application program's performance; and (4) our scheme does not degrade the service availability of the application while detecting and reclaiming memory leaks. We have implemented a prototype that works with the GNU C library and with the Linux kernel. Our prototype has been tested and evaluated with various real-world applications. Our results show that the computational overhead of our approach is around 2% of that incurred by the conventional memory allocator in terms of throughput and average response time. We also verified that the prototype successfully suppressed address space expansion caused by memory leaks when the applications are run on synthetic workloads. Copyright © 2010 John Wiley & Sons, Ltd.</P>

Role of Barium Swallow in Diagnosing Clinically Significant Anastomotic Leak following Esophagectomy

Simon Roh,Mark D. Iannettoni,John C. Keech,Mohammad Bashir,Peter J. Gruber,Kalpaj R. Parekh 대한흉부외과학회 2016 Journal of Chest Surgery (J Chest Surg) Vol.49 No.2

Background: Barium swallow is performed following esophagectomy to evaluate the anastomosis for detection of leaks and to assess the emptying of the gastric conduit. The aim of this study was to evaluate the reliability of the barium swallow study in diagnosing anastomotic leaks following esophagectomy. Methods: Patients who underwent esophagectomy from January 2000 to December 2013 at our institution were investigated. Barium swallow was routinely done between days 5–7 to detect a leak. These results were compared to clinically determined leaks (defined by neck wound infection requiring jejunal feeds and or parenteral nutrition) during the postoperative period. The sensitivity and specificity of barium swallow in diagnosing clinically significant anastomotic leaks was determined. Results: A total of 395 esophagectomies were performed (mean age, 62.2 years). The indications for the esophagectomy were as follows: malignancy (n=320), high-grade dysplasia (n=14), perforation (n=27), benign stricture (n=7), achalasia (n=16), and other (n=11). A variety of techniques were used including transhiatal (n=351), McKeown (n=35), and Ivor Lewis (n=9) esophagectomies. Operative mortality was 2.8% (n=11). Three hundred and sixty-eight patients (93%) underwent barium swallow study after esophagectomy. Clinically significant anastomotic leak was identified in 36 patients (9.8%). Barium swallow was able to detect only 13/36 clinically significant leaks. The sensitivity of the swallow in diagnosing a leak was 36% and specificity was 97%. The positive and negative predictive values of barium swallow study in detecting leaks were 59% and 93%, respectively. Conclusion: Barium swallow is an insensitive but specific test for detecting leaks at the cervical anastomotic site after esophagectomy.

상수도 배관에서 두 지점의 동시 누수에 따른 신호특징 분석

이영섭(Young-Sup Lee) 한국비파괴검사학회 2015 한국비파괴검사학회지 Vol.35 No.1

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. Intelligent leak detection is an essential component of a underground water supply pipeline network such as a smart water grid system. In this network, numerous leak detection sensors are needed to cover all of the pipelines in a specific area installed at specific regular distances. It is also necessary to determine the existence of any leaks and estimate its location within a short time after it occurs. In this study, the leak signal properties and feasibility of leak location detection were investigated when concurrent leaks occurred at two points in a pipeline. The straight distance between the two leak sensors in the 100A sized cast-iron pipeline was 315.6 m, and their signals were measured with one leak and two concurrent leaks. Each leak location was described after analyzing the frequency properties and cross-correlation of the measured signals.

지하매설 상수도배관의 누수지점 탐지를 위한 탄성파 검출연구

이영섭,윤동진,정중채,이승석 한국비파괴검사학회 2003 학술대회 논문집 Vol.- No.1

Leaks in underground pipelines can cause social, environmental and economical problems. One of a good contermeasures of leaks is to find and repair of leak points of pipes. Leak noise is a good source to identify thc location of leak points of pipelines. Although there have been several methods to detect thc leak location with leak noise, such as listening rods, hydrophones or ground microphones, they were not so efficient tools. In this paper, two accelermeters are used to detect leak locations which could provide an easier and effcient method. The filtering, signal processing and algorithm is described for the detection of leak location. A 120m-long pipeline system for experiment is installed and the results with the system show that the algorithm with the two accelerometers gives very accurate pinpointing of leaks. Theoretical analysis of sound wave propagation speed in underground pipes is also described.

여성 긴장성 요실금 환자에서 Stress Leak-Point Pressure와 Maximal Urethral Closure Pressure의 비교

김대우,박석산 大韓泌尿器科學會 1997 Korean Journal of Urology Vol.38 No.10

소득금액변동통지 제도의 비판적 검토 및 대안

송동진,박훈 한국조세법학회 2018 조세논총 Vol.3 No.2

현행세법은 사외유출소득의 귀속자가 지배주주인 대표자인 경우 과세관청이 그 소득을 근로소득인 상여로 소득처분하도록 규정하고, 귀속불분명인 소득은 대표자에게 귀속한 것으로 의제한다(인정상여). 그 후속조치로 소득금액변동통지가 법인에게 송달된 시점에 법인이 문제된 소득을 소득처분에 의한 소득귀속자에게 소득을 지급한 것으로 의제된다. 현행세법의 소득금액변동통지 제도에는 다음과 같은 문제점이 있다. 첫째, 대표자에 대한 인정상여는, 대표자가 사외유출소득의 귀속자를 밝힐 수 없거나 자신에게 귀속하지 않았음을 밝힌 경우까지도 대표자귀속을 의제하는 과도한 불이익을 과함으로써 과잉금지원칙에 위배하여 재산권을 침해하는 것으로서 헌법에 위반된다. 대표자에 대한 인정상여 제도가 위헌인 이상, 그것을 전제로 한 소득금액변동통지의 지급의제도 위헌이라고 보아야 한다. 소득금액변동통지는 법인의 ‘지급’이 있었는지 의심스러운 사안이나 지급대상자가 불확실한 경우도 적용대상으로 하고 있고, 이는 원천징수의무를 지우기 위한 입법의 전제조건을 제대로 갖추지 못한 것이다. 둘째, 현행세법은 원천납세의무는 사외유출소득의 원인행위가 있었던 과세기간의 종료시점에 성립하는 것으로 하면서도, 원천징수의무는 소득금액변동통지의 시점에 성립하는 것으로 규정하고 있다. 이에 따라 원천납세의무와 원천징수의무의 성립시기에 큰 괴리가 발생할 수 있고, 이는 원천징수세율이 변경된 경우와 원천징수의무에 대한 제2차 납세의무자인 과점주주의 결정에 관하여 해석론상의 문제점을 야기한다. 셋째, 소득금액변동통지에 따르는 세액의 납부기한은, 사외유출시점에 소득이 지급된 것으로 처리하는 경우와 비교하면, 법인에게 원천징수세액의 납부기한을 유예하고 납부불성실 가산세를 면제해주는 셈이 된다. 사외유출된 소득이 지배주주에게 귀속되는 것은 배당의 지급으로 볼 여지가 충분하다. 사외유출이 제재를 받아야 할 행위임에도 편법적 방법으로 배당을 지급한 원천징수의무자에게 정상적인 배당의 지급보다 혜택을 부여하는 것은 부당하다. 넷째, 소득금액변동통지에 의하여 소득지급 의제의 효과가 생기는 점을 고려하여 대법원이 소득금액변동통지를 항고소송의 대상인 행정처분으로 보고 있기 때문에, 소득금액변동통지에 의한 원천징수에 대한 불복절차는 일반적인 원천징수에 대한 것과 확연히 다르게 되었다. 이로 인하여 원천징수에 관한 구제절차의 일관성이 상실되었다. 이러한 문제점을 해결하기 위해서는 현행세법을 다음과 같이 개정할 필요가 있다. 지배주주인 대표자에게 귀속된 사외유출소득은 상여가 아니라 배당으로 과세하는 것이 타당하다. 그 경우 법인소득의 사외유출을 실질적 배당의 지급으로 파악할 여지가 생기게 된다. 소득금액변동통지 제도를 폐지하고, 법인 소득의 사외유출을 실질적 배당의 지급으로 파악하여 법인의 원천징수의무를 인정하는 것이 합리적이다. 귀속불분명인 사외유출 소득은 인정상여처분에 의하여 대표자에 대한 귀속을 의제할 것이 아니라 간접사실에 의한 추인에 의하여 인정하거나 추정규정을 두는 것이 바람직하다. 그리고 이에 대응하여 법인의 대표자에 대한 소득의 지급을 추정하는 규정을 검토할 수 있다. When the income leaked from a corporation ("leaked-income") belongs to its representative of the corporation, the controlling shareholder, current tax law subscribes that the tax official decides the income as bonus which is labor income, and deems that the leaked-income whose holder is uncertain ("leaked-uncertain-income") is attributed to the representative director ("representative") (deemed-bonus). As a subsequent action the corporation is deemed to have paid the income to the person designated as holer by tax official's income decision at the time when the notice of change in income ("NCI") is served to the corporation. The NCI system in current tax law has problems as belows. Firstly, deemed-bonus for the representative is unconstitutional because it infringes proportionality and impairs property rights by imposing excessive disadvantage of deeming the income to belong to the representative even where he or she could not confirm the holder of the income or proves that the income does not belong to him or her. Since deemed-bonus for the representative is unconstitutional, deemed payment by NCI based on deemed-bonus for the representative is to be regarded as unconstitutional. NCI lacks the prerequisite for legislation to impose withholding tax for it covers the cases where whether there was a payment by corporation is dubious or the person paid by the corporation is uncertain. Secondly, current tax law provides that withholding tax liability is established at the time of NCI, while prescribing that the original tax liability is established at the end of the tax period when there was the causative act of leaked-income. Accordingly, big discrepancy can arise between the establishment timing of withholding tax liability and that of original tax liability, which gives rise to problems about the case when withholding tax rate changes and, determining the controlling (oligopoly) shareholder who is subject to the second stage tax liability for corporation's tax liability. Thirdly, due date for withholding tax accompanied by NCI is, when compared to the case of treating the leaked-income is paid at the time of leakage, on par with permitting grace period to the corporation and giving exemption to additional tax. It is highly plausible to see the leaked-income belonging to controlling shareholders as payment of dividend. It is unjust to vest advantages to the withholding liability holder who paid dividend expediently than regular payment of dividend despite income leakage from corporation is to be sanctioned. Fourthly, supreme court ruled that NCI is the object of administrative appellate litigation considering that the effect of deeming the income to be paid by NCI. Consequently the appellate procedure concerning withholding liability by NCI becomes quite different from that about general withholding liability, consistency of appellate procedures of withholding liabilities was impaired. To solve the problems above, current tax law needs to be amended as belows. It is appropriate to tax leaked-income belonging to controlling shareholder-representative not as bonus but as dividend. In that case there arises a possibility to treat the leakage of corporate income as substantive payment of dividend. It is resonable to abolish the system of NIC, and treat the leakage of corporate income as substantive payment of dividend and impose corporation withholding liability for it. And it is desirable to attribute leaked-uncertain-income to representative by taking into account all facts and considerations, or to introduce presumption clause rather than deeming leaked-uncertain-income to be attributed to representative by deemed-bonus clause. And in response to this clause presuming the payment of income to representative can be considered.