• 센서학회지
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• 제24권1호
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• pp.6-9
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• 2015

Conventional leak detectors are widely based on helium gas sensors. However, the usage of hydrogen sensors in leak detectors has increased because of the high prices of helium leak detectors and the dearth in the supply of helium gas. In this study, a hydrogen leak detector was developed using solid-state hydrogen sensors. The hydrogen sensors are based on Park-Rapp probes with heterojunctions made by oxygen-ion conducting Yttria-stabilized zirconia and proton-conducting In-doped $CaZrO_3$. The hydrogen sensors were used for determining the potential difference between air and air balanced 5 ppm of $H_2$. Even though the Park-Rapp probe shows an excellent selectivity for hydrogen, the sensitivity of the sensor was low because of the low concentration of hydrogen, and the oxygen on the surface of the sensor. In order to increase the sensitivity of the sensor, the sensors were connected in series by Pt wires to increase the potential difference. The sensors were tested at temperatures ranging from $500-600^{\circ}C$.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.65-71
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• 2001

In this paper, acoustic omission technique(AE) 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 searching for the point of highest signal amplitude by comparing wi th several fired sensors.

• 한국안전학회지
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• 제15권2호
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• pp.59-62
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• 2000

Almost accidents related with gas have started with the leakage of LPG(Liquefied Petroleum Gas) in the open air. But experimental data of LPG leak jet are difficult to find because the safety of experiment is hard to secure and its phenomenon is not steady but transitional. This study is focused on the phenomena of injection jet of liquid butane to the open air. Simple experiment shows that only liquid butane jet in the open air is possible due to the slow vaporization because of low temperature difference between the liquid and air and low vapor pressure of liquid butane. Comparing with the water, 25~40% more liquid butane flow through the tube under the same pressure difference driving.

• 설비공학논문집
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• 제26권2호
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• pp.91-96
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• 2014

An acoustical model for detecting the leak location in a buried gas pipeline has been developed. This model is divided into an experimental model for sound diagnosis, and a theoretical model for sound prediction, which is based on the transfer matrix method, representing the sound pressure and the volume velocity as state variables. The power spectrum is measured by attaching only one microphone to the closed end pipe. It has been shown that the response magnitude of acoustic pressure signals calculated by the acoustical model depends upon the thickness and diameter of a pinhole. The validity for the acoustical model has been verified through a comparison between the measured and calculated results.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.282-288
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• 1997

The purpose of this paper is to predict the situation of leak in closed space using an Artificial Neural Network (ANN). The existing system can't monitor the whole He situations with on/off signals. Especially the first stage of data determines the leak spot and intensity is disregarded in gas accidents. To complement these faults, a new prototype of monitoring system is proposed. Ihe system is composed of'sensing systenL data acquisition system computer, and ANN implemented in software and is capable of identifying the leak spot and intensity in closed space. The concentration of gas is measured at the 4 different places. The network has 3 layers that are composed of 4 input Processing Element (PE),24 hidden PEs, md 4 output PEs. The ANN has optimum condition through several experiments and as a consequence the recognition rate of93.75% is achieved finally

• Nuclear Engineering and Technology
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• 제30권5호
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• pp.403-415
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• 1998

The CANDU 6 reactor assembly consists of an array of 380 pressure tubes, which are installed horizontally in a large cylindrical vessel, the Calandria, containing the low pressure heavy water moderator. The pressure tube is located inside the calandria tube and the annulus between these tubes, which forms a closed loop with $CO_2$ gas recirculating, is called the Annulus Gas System(AGS). It is designed to give an alarm to the operator even for a small pressure tube leak by a very sensitive dew point meter so that he can take a preventive action for the pressure tube rupture incident. To judge whether the operator action time is enough or not in the design of Wolsong 2,3 & 4, the Leak Before Break(LBB) assessment is required for the analysis of the pressure tube failure accident. In order to provide the required data for the LBB assessment of Wolsong Units 2, 3, 4, a series of leak detection capability tests was performed by injecting controlled rates of heavy water vapour. The data of increased dew point and rates of rise were measured to determine the alarm set point for the dew point rate of rise of Wolsong Unit 2. It was found that the response of the dew point depends on the moisture injection rate, $CO_2$ gas flow rate and the leak location. The test showed that CANDU 6 AGS can detect the very small leaks less than few g/hr and dew point rate of rise alarm can be the most reliable alarm signal to warn the operator. Considering the present results, the first response time of dew point to the AGS $CO_2$ flow rate is approximated.

• 한국가스학회지
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• 제11권4호
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• pp.47-53
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• 2007

고압 가스 배관망의 안전관리는 매우 중요한 문제로 배관의 외적 손상으로 구멍이 생길 경우 발생하는 누출은 폭발 및 환경오염을 포함한 막대한 경제적 손실을 야기할 수 있다. 누출 검지를 위한 PLDS(Pipeline leak detection system린 기술로 저압확장파 검지 기술이 적용되고 있으며 본 논문에서는 CFD++ 상용코드를 활용하여 배관 누출시 유동특성을 이론적으로 해석하여 저압확장파의 발생 메커니즘과 음속으로 확장되는 전파특성을 규명하였다. 또한 긴 배관망에 적용하기 위한 1차원 해석 방법을 제시하고 신뢰성을 CFD해석 결과로 검증하였다.

• 한국안전학회지
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• 제35권5호
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• pp.15-21
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• 2020

Quantitative risk assessment (QRA) is used as a legal or voluntary safety management tool for the hazardous material industry and the utilization of the method is gradually increasing. Therefore, a leak frequency analysis based on reliable generic data is a critical element in the evolution of QRA and safety technologies. The aim of this paper is to derive the leak frequency function that can be applied more flexibly in QRA based on OGP report with high reliability and global utilization. For the purpose, we first reviewed the data on the 16 equipments included in the OGP report and selected the predictors. And then we found good equations to fit the OGP data using non-linear regression analysis. The various expectation functions were applied to search for suitable parameter to serve as a meaningful reference in the future. The results of this analysis show that the best fitting parameter is found in the form of DNV function and connection function in natural logarithm. In conclusion, the average percentage error between the fitted and the original value is very small as 3 %, so the derived prediction function can be applicable in the quantitative frequency analysis. This study is to contribute to expand the applicability of QRA and advance safety engineering as providing the generic equations for practical leak frequency analysis.

• 한국가스학회지
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• 제12권2호
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• pp.48-52
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• 2008

산업의 성장으로 가스사용량이 증가함에 따라 가스설비, 화학플랜트 등 시설 또한 점차로 증가하고 있으나, 가스에 대한 안전관리는 여전히 미흡한 실정이다. 공장과 가정에서 많이 사용되고 있는 메탄은 천연가스의 주성분으로 가연성이면서 폭발성가스이어서 그에 대한 안전관리도 매우 중요하다. 그 한 가지 방안으로 $3.2\;{\mu}m$ 중적외선 영역의 LED 및 PD를 이용하여 메탄가스누출검지시스템을 개발하고자 한다. 이 파장대역의 센서로 레이저를 이용할 경우 고열이 발생하여 초저온 냉각장치가 필요하나 LED는 상온에서 동작함으로 냉각장치가 필요 없다. 그래서 초소형이나 휴대용으로 구현이 가능하다. $3.2\;{\mu}m$ 부근의 파장대역은 $1.67\;{\mu}m$에 비하여 메탄흡수강도가 강하여서 극미량의 가스탐지가 가능하고 응답성 또한 빠르다. 본 연구에서는 이를 상용화하여 매설 및 노출배관 등 가스설비의 가스누출을 보다 정확하고 신속히 검지함으로써 사고를 미연에 방지하고 그 피해를 최소화하고자 한다.

• 한국가스학회지
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• 제23권2호
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• pp.17-27
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• 2019

화학물질의 사용 증대와 더불어 위험물 및 독성가스 누출 사고가 빈번하게 일어나고 있다. 그 중에서도 위험물 저장설비 사고는 누출이 감지되었을 때 대응하기 위한 초동 조치가 가장 중요하지만, 전적으로 조업자에 의한 경험에 비중이 크기 때문에, 잘못된 판단으로 인한 더 큰 물적, 인적 피해가 발생할 가능성이 높다. 본 연구는 기존 고정식 감지기를 통한 알람 발생 후 수동적인 대응을 취하는 현 접근 방식에서 벗어나, 오픈소스기술을 적용하여 쉽게 제작이 가능한 로봇 플랫폼에서 작동하는 이동식 센서를 활용한 능동적인 누출원 추적 시스템을 설계하였다. 아울러 프로토타입 시스템의 검증을 통해 누출 초기의 정확한 현장 상황파악 및 조기대응을 바탕으로 사고의 확산 및 피해 최소화의 기틀을 마련하고자 하였다.