• 비파괴검사학회지
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• 제28권2호
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• pp.151-156
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• 2008

반도체나 디스플레이 제조 등 진공공정의 리크검출에는 질량분석기형(mass spectrometer type) 헬륨 리크검출기(leak detector)가 사용되고 있다. 이 기기를 이용해서 안정된 측정값을 얻기 위해서는 장치 내부에 내장된 투과형(permeation type) 표준리크(standard leak)를 이용해서 자주 spectrometer를 교정해야 한다. 본 연구에서 질량분석기형 리크검출기의 비교교정 장치의 개발과 교정방법에 대한 연구결과를 언급하였다. 따라서 이 기술을 이용하면 질량분석기형 리크검출기를 구비하고 있는 현장에서도 표준리크의 비교교정이 가능하게 된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.84-89
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• 2003

Water leak is one of topics with great concern in Korea and many other countries, because of decreasing water supplies and the deterioration of old pipeworks. Correlation techniques have been widely used in leak detection of water pipes, which allow to locate a leak point based on the correlation of leak noise at two sites along water pipes. In this study, both the cross-correlation method and the conventional arrival time difference method are applied in order to analyze and to locate a leak point of a water pipe. In experiment, a 150 m of whole length waterwork pipeline system was constructed in a ground, and several types of leak noise were installed on the pipeline in order to control leak condition. Both the cross-correlation technique and the arrival time difference method showed favorable results at leak detection with the experimental pipeline system.

• 한국소음진동공학회논문집
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• 제14권2호
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• pp.95-104
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• 2004

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, accelermeters aroused 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 120m-long and a 70m-long experimental pipeline systems are installed and the results with the systems show that the algorithm with the accelerometers offers accurate pinpointing for leaks location detection. Theoretical analysis of sound wave propagation speed of water in underground pipes, which is critically important in leak locating, is also described.

• Nuclear Engineering and Technology
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• 제47권3호
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• pp.332-339
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• 2015

The leak before break (LBB) concept is widely used in designing pipe lines in nuclear power plants. According to the concept, the amount of leaking liquid from a pipe should be more than the minimum detectable leak rate of a leak detection system before catastrophic failure occurs. Therefore, accurate estimation of the leak rate is important to evaluate the validity of the LBB concept in pipe line design. In this paper, a program was developed to estimate the leak rate through circumferential cracks in pipes in nuclear power plants using the Henry-Fauske flow model and modified Henry-Fauske flow model. By using the developed program, the leak rate was calculated for a circumferential crack in a sample pipe, and the effect of the flow model on the leak rate was examined. Treating the crack morphology parameters as random variables, the statistical behavior of the leak rate was also examined. As a result, it was found that the crack morphology parameters have a strong effect on the leak rate and the statistical behavior of the leak rate can be simulated using normally distributed crack morphology parameters.

• Current Optics and Photonics
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• 제6권2호
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• pp.137-142
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• 2022

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 m³/h. Results show that frequency shifts detected by FBG sensors can be used to detect leaks in pipelines.

• 비파괴검사학회지
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• 제7권1호
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• pp.7-17
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• 1987

Leak detection testing for the pipeline system was performed by the acoustic emission method. It was found that the detected signal spectrum was influenced by the frequency response of sensors and pressure changes. AE parameters and frequency spectrum distributions were used to analyze the leak signals. The slope rise time of AE parameters were the important factors for distinguishing leak signals. The amplitude of leak signal was more affected by the changes of leak, rate and pressure than those of leak type.

• 한국가스학회지
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• 제10권3호
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• pp.27-33
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• 2006

본 논문에서는 가스 파이프라인 내의 누출 현상이 파이프라인 출구 압력 변화에 미치는 영향을 분석하였다. 경사진 지형적 영향을 고려하기 위하여, 보정된 Weymouth 식이 본 연구에서 사용되었다. 누출 영향을 분석하기 위하여, 수평관, 상향 및 하향 경사관 각각에서 누출 현상이 없을 경우와 누출 현상이 발생할 경우에 대하여 출구 압력과 입구 압력에 대한 출구 압력 비율을 비교하였다. 그 후, 누출 위치가 출구 압력에 미치는 영향에 대하여도 모든 파이프라인 경사각에 대하여 분석하였다.

• 항공우주기술
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• 제11권2호
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• pp.103-108
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• 2012

발사체의 신뢰성과 추진제 또는 가스의 누설은 매우 밀접한 상관관계를 갖는다. 본 논문에서는 누설에 대한 정성적인 분석을 위한 누설량의 정의와 각 단위계의 변환 관계를 소개하였다. 또한 누설량에 영향을 미치는 인자를 분석하였다. 발사체 기밀시험에 사용하는 가스의 품질 요구조건과 발사체 또는 부품의 기밀을 확인하기 위한 여러 가지 시험 방법을 소개하였다. 아울러 발사체의 추진시스템에 대한 기밀시험에서 사용된 방법과 절차를 간략히 기술하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.821-826
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• 2003

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 the location of leak points of pipelines. Although there have been several methods to detect the leak location with leak noise, such as listening rods, hydrophones or ground microphones, they were not so efficient tools beca. In this paper, two accelermeters are used to detect leak locations which could provide an easier and efficient 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.

• 대한기계학회논문집A
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• 제26권5호
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• pp.864-871
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• 2002

Acoustic emission(AE) technique has been applied to not only mechanical property testing but also on-line monitoring of the entire structure or a limit zone only. Although several AE devices have already been developed for on-line monitoring, the price of these systems is very high and it is difficult for the field to apply yet. In this study, we developed a specially designed PC-based leak detection system using A/D board. In this paper, AE technique has been applied to detect leak for heat exchanger by analyzing the characteristics of signal obtained from leak. It was confirmed that the characteristics of the signal generated by the turbulence of gas in the heat exchanger is narrow band signal having between 130-250kHz. Generally, the amplitude of leak signal is increased as the leak size increasing, but showed no significant change at frequency characteristic. Leak source location can be found by determining for the paint of highest signal amplitude by comparing with several fixed sensors. In this paper, AE results are compared with the PC-based leak detection system using A/D board.