• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.48-53
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• 2012

This paper is purposed to develop portable electric instrument to select NI-9223(National instrument comp.) and clamp meter(HIOKI comp.), which can be used in developing electric instrument, to detect leakage current(ZCT) and current(CT) signals. In this paper, The electric instrument that can interface with current and leakage current instrument(HIOKI 9283), is developed by NI-9223 of NI comp.. HIOKI clamp meter can measure current signals certainly by high-sensitivity of 10 ${\mu}A$ resolution(leakage current : at 10 mA range) and current 1~200A range. The NI-9223 use four 16-bit analog-to-digital converters(ADCs) for true simultaneous sampling at up to 1 MS/s per channel. NI-9223 can synchronize all analog input modules installed in the same chassis to share the same start clock and/or sample clocks. The monitoring program is developed by SignalExpress of LabVIEW. The monitoring program are developed to analyze at simultaneous sampling on electrical signals such as leakage current(ZCT) and current(CT). The developed system verification tests were conducted, and portable electric instrument can be used in place which requires analysis of the actual electrical signal.

• Fire Science and Engineering
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• v.30 no.4
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• pp.103-110
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• 2016

While the demand for the gas system fire extinguishers increases every year, there are insufficient safety measures for assessing the extinguishing performance, such as system safety and reliability in the preparation of increasing demand, which has emerged as a social problem. One of the most critical causes of accidents occurring with the gas extinguishing system is pressure leakage from the extinguishing agent storage container. This is considered to be one of the critical factors on which the success of fire suppression depends. In this study, its safety measure was studied, Because it was deemed urgently necessary. The newly developed pressure leakage monitoring system is a system monitoring storage condition, pressure, leakage and discharge of the storage container related to agent concentration, which is one of the critical factors for fire suppression. This was developed to be applicable to the $CO_2$ and HFC-23 systems. Therefore, for structural safety analysis, the safety performance was verified by the fluid structure coupling analysis of the safety problems that may occur when the pressure leakage monitoring system is applied to the gas fire extinguisher. For analysis programs, the FloEFD program from Mentor Graphics was used for computational fluid dynamics analysis and ABAQUS from Dassault Systems was used for structural analysis. From the result of numerical analysis, the structure of $CO_2$ did not develop plastic deformation and its safety was verified. However, plastic deformation and deviation issue occurred with the HFC-23 monitoring system and therefore verified the structural safety of pressure leakage monitoring system by data obtained from redesigning and adjusting the condition of numerical interpretation three times.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.107-112
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• 2017

In recent years, electric shock accidents due to electric leakage currents of household appliances such as computers, TVs, refrigerators, and LED lights are continuously occurring in homes and industrial buildings. And it is not easy to check the leakage current of each household appliances connected in parallel at the rear end of the module. In addition, the leakage current flowing through the path of the normal current other than the existing current leakage circuit breakers are installed in the distribution box, only the function to cut off the power when the leakage. Therefore, there are various disasters such as electric shock and fire caused by short circuit of household appliances, and the risk of such leakage current is seriously presented. In this paper, we propose a method to implement a leakage monitoring system that can be monitored at all times using Zigbee communication based on IEEE 80215.4, which has advantages in low power and low cost among short range wireless communication systems.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.2
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• pp.14-20
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• 2011

The end of design lifetime for Wolsong unit 1 will be reached on 20th November in 2012. So the license renewal documents for the continuous operation of Wolsong unit 1 is under reviewing now. Major components of primary system such as pressure tubes, feeder pipes including delayed neutron monitoring system tubing are being replaced and many components of secondary system are also being repaired. In this paper, the assessment on the wear degradation of delayed neutron monitoring system tubing(on the other hand, DN tube was called) was performed for the ageing management of the same component. The wear defects of this component was one of causes that resulted in heavy water leakage accidents. Therefore design specifications of Wolsong uint 1 and heavy water leakage accidents of pressurized heavy water reactors were reviewed and causes of wear defect for DN tubes were analyzed. Wear propagation equations based on the heavy water leakage history were made and the proper repairing time was possible to be expected if the continued operation was considered. Finally design change items of DN tubes that were conducted for the long term operation of Wolsong unit 1 are introduced.

• Journal of the Korean GEO-environmental Society
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• v.11 no.9
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• pp.15-25
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• 2010

The main objective of this study was to offer informations about long-term seepage behavioral characteristics and to find a leakage safety management method for Juam Dam and Imha Dam, a central cored rockfill dams in Korea by the evaluating the automatically monitored leakage data. In the water leakage monitoring of fill dam, the generation of abnormal water leakage is difficult to directly detect due to the effect of outside factors such as the component of rainfall inherent in the observation value. Therefore, conventionally estimation methods of water leakage quantity were applied by multiple regression analysis considering reservoir water level, rainfall, etc.. However, the estimated error of rainfall component is relatively big in these method. This paper identifies the seepage characteristic of each dams which is not directly affected by rainfall through the hydrograph separation analysis and 3 dimensional analytical method, and thinks a leakage management method. It was noticed that two dams had site specific seepage behaviour features and were in stable state with the decreasing leakage quantity. It was also found that hydrograph separation method might be applicable to leakage safety management method.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.155-162
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• 2019

To reduce the secondary damage caused by leakage accidents in plant piping systems, a constant surveillance system is necessary. To ensure leaks are promptly addressed, the surveillance system should be able to detect not only the leak itself, but also the location of the leak. Recently, research to develop new methods has been conducted using cameras to detect leakage and to estimate the location of leakage. However, existing methods solely estimate whether a leak exists or not, or only provide two-dimensional coordinates of the leakage location. In this paper, a method using multiple cameras to detect leakage and estimate the three-dimensional coordinates of the leakage location is presented. Leakage is detected by each camera using MADI(Moving Average Differential Image) and histogram analysis. The two-dimensional leakage location is estimated using the detected leakage area. The three-dimensional leakage location is subsequently estimated based on the two-dimensional leakage location. To achieve this, the coordinates (x, z) for the leakage are calculated for a horizontal section (XZ plane) in the monitoring area. Then, the y-coordinate of leakage is calculated using a vertical section from each camera. The method proposed in this paper could accurately estimate the three-dimensional location of a leak using multiple cameras.

• Transactions on Electrical and Electronic Materials
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• v.7 no.5
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• pp.247-251
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• 2006

The traction DC feeder cable is one of the key devices for the safety operation of subway system, but for low voltage DC feeder cable (<3000 V) for subway, little attention has been paid by investigators on its online monitoring technology. With an introduction of cable laying and operation environment for the cable, this paper investigated the on-line monitoring technology of 1500 V DC feeder cable of subway. Firstly, in the text, the fault model of 1500 V DC cable was proposed based on the analysis of the fault type of the DC feeder cable, and then put forward synthetically on-line monitoring discharge signal and DC leakage current signal to assess DC feeder cable insulating state. The results of laboratory experiment prove that the proposed methods are feasible and can be implemented on-line monitor on DC feeder cable of subway.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.473-475
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• 2001

We report the state of the development of monitoring system for 72.5kV GIS. In the first, the usual outline of the monitoring and diagnostic system for GIS was mentioned, and the detailed specifications and state of development were also described. Especially, we present items of monitoring for GIS such as the operating counter of CB, the leakage condition of $SF_6$ gas, the surge counter of LA and the leakage current of LA.

• Geophysics and Geophysical Exploration
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• v.9 no.2
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• pp.155-162
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• 2006

An abnormal seepage flow, which is mainly caused by the piping, is one of the major reasons for embankment dam failure. A leakage detection is therefore a vital part of an embankment dam's monitoring. Resistivity method, which is an efficient tool to detect leakage zones, has been used all over the world for an embankment dam's monitoring. Although the resistivity method gives us very useful information about the leakage problem, there is no more quantitative interpretation than the low resistivity zones in the 2-dimensional resistivity section are regraded simply as the anomalous seepage zones. Recently, resistivity monitoring technique is applied for the detection of leakage zones. However, its interpretation still remains in the stage of presenting the resistivity ratio itself. An increased seepage flow increases a porosity and an increasing porosity decreases the dam's stability. Therefore, the porosity is one of the major factors for an embankment dam's stability. Based on Archie's experimental formula, we try to evaluate a porosity distribution from the resistivity data which is obtained on the dam's crest. We also attempt to represent a procedure to evaluate a safety index of the embankment dam from the resistivity monitoring data.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.5
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• pp.422-429
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• 2013

It is of great importance to localize leakages in complex pipelines for assuring their safety. A sensor array that can detect where leakages occur enables us to monitor a wide area with a relatively low cost. Beamforming is a fast and efficient algorithm to estimate where sources are, but it is generally made use of in free field condition. In practice, however, many pipelines are placed in a closed space for the purpose of safety and maintenance. This leads us to take reflected waves into account to the beamforming for interior leakage localization. Beam power distribution of reflected waves in a closed space is formulated, and spatial average is introduced to suppress the effect of reflected waves. Computer simulations and experiments ensure how the proposed method is effective to localize leakage in a closed space for structural health monitoring.