• Journal of the Society of Disaster Information
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• v.16 no.1
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• pp.144-154
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• 2020

Purpose: This paper is a fundamental study on the applicability of the smart bolt developed for monitoring system to detect the leakage of water supply valve. Method: A leak detection experiments were conducted using the smart bolt having embedded strain sensors and accelerometer. The smart bolt used in study meets the allowable criteria of torque and tensile stress for water supply system, and it can be applied to a joint of the water supply valve by behaving well within the allowable limits. Result: As a result of the simulated leak tests, a leak signal at the valve leak point was detected in a band of 60Hz, and the main pipe leaking point was observed to produce a leak signal having much higher frequency than that of the valve leak point. This seems to result in a total coupled vibration under unconfined conditions of the pipes. Conclusion: The smart bolts appeared applicable to detecting a leaking signal from the water supply valve.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.14-18
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• 2021

Electric Vehicle industry requires high technologies to stabilize apparatuses for the Coolant heater manufacturing. Vibrations of Leak Machine are one of the most critical factors for causing delivered of the defective product or poor inspection, which are the main reasons of the defects. In this study, the structure of the Leak Machine was analyzed through the experiment and the computer simulation to investigate the main reasons of the vibrations, and further to alter the design for the improved stability. And that design alterations were applied to the machine to identify the effects of those alterations. The result of the study shows that design alterations of the Leak Machine can effectively suppress about 97.8% of the vibrations, and further can improving the Inspection precision of the Coolant heater.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.406-408
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• 2019

The motor applied to electric water pump used in automobiles is the canned type motor structure. The rotor, which is the driving component of the motor, is located in the bulkhead structure of the plastic injection molding, and rotates while immersed in the antifreeze. Plastic Injection Stator is placed on the outside of the bulkhead structure so that the rotor can rotate. The configuration of the rotor consists of magnet, core and shaft. In the case of magnet and core, it is very important to keep the parts sealed because it is a material that is corroded by moisture. When mounted on a vehicle, it must be capable of driving at $120^{\circ}C$ ambient conditions and should not leak under pressure of 1 bar or more. In this paper, we designed and implemented a Leak inspection automation system using helium to check the defects of the electric water pump developed satisfying this condition.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.180-188
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• 1994

This study was designed to investigate qualitatively whether respirators now being used in workplaces tit workers iflfaces well or not. Leak sites were determined after exposing the subjects to fluorescent aerosol and were analyzed by gender, brand and manufacturing nation. The results were as follows ; 1. Among those leak sites which were classified into four areas(nose, cheek, lip and chin), test aerosol was mostly deposited on the nose and the cheek areas. 2. The mean number of leak sites observed from the female subjects were 2.3 while the number were 2.2 from the male subjects. The most frequently observed leak site was nose and followed by chin, lip and cheek in descending order of frequency. 3. Among different brands of respirators, different leak sites were observed. Test subjects wearing the Sand N brands were more heavily exposed than those of wearing the D and M brands. 4. No significant difference of the number of leak sites were found between Korean-made and American-made masks. However, the most frequent leak site observed for the Korean-made ones was the nose area while it was the chin area for the American-made ones. 5. Analyses of 97 leak sites by shape showed that 27(27.8%) were point types, 54(55.7%) diffuse types and 16(16.5%) streamline types. 6. Test subjects indicated that the facepieces of Korean-made respirators were harder and smaller in size than those of American-made one. The most comfortable respirator selected was the respirator by the N Co. and the most uncomfortable one was the respirator by the D Co. This study suggests that many half-mask respirators now being used in the workplaces may not fit to workers well. Therefore, when selecting respirators, employers are advised to test respirators if they fit to workers well. And manufacturers are recommended to produce effective and comfortable respirators tested qualitatively and quantitatively not only in the laboratory but also in the field.

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.40-49
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• 2016

When a leak occurs in the buried pipelines, The leak locations are able to detected by using the vibration sensors. These leak detection system, intended for incompressible fluid, such as water, are of using the wave propagation velocity and a signal arrival time delay between the sensors. In this paper, to develop a leak location detection system for a compressible fluid such as gas, the conventional detection methods have been studied, improved, and verified through the experiment using the compressed air. It confirmed that it is possible to detect the leak location for compressible fluid in the buried pipelines and to be applicable to the development of a leak location detection system in buried pipelines for gas.

• Journal of The Korean Society of Clinical Toxicology
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• v.4 no.2
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• pp.122-127
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• 2006

Purpose: It is not easy to detect carbon monoxide (CO) leakage, and CO-intoxicated patients do not show a specific set of symptoms. The aims of this study are to clinically evaluate patients with CO gas intoxication from a CO leak at an underground shopping center, and to discuss the establishment of a disaster prevention plan. Methods: A total of 51 patients intoxicated by CO gas exposure in a gas disaster at a underground shopping center in Seoul on September 8, 2006 were enrolled in this study, and the patients' medical records were retrospectively reviewed. Results: The mean patient age was $29.4{\pm}6.3$. The initial mean COHb level was $14.98{\pm}6.97%$. The number of patients with COHb greater than 25% was three, and six patients experienced a syncopal attack. Only one patient-was treated with hyperbaric oxygen therapy. However, none of the patients complained of severe neurologic or cardiovascular symptoms. Conclusion: The symptoms of CO intoxication are non-specific and difficult to define, and the detection of CO leak-age is difficult. Thus, workplaces should be equipped with leakage sensors and automatic alarm systems and should have develop disaster prevention plans.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.6
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• pp.469-476
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• 2008

Condition based maintenance(CBM) for the preventive diagnosis of important equipments related to safety or accident in power plant is essential by using the suitable methods based on actual power plant conditions. To improve the reliability and accuracy of the measured value at the minute leak situation, and also to monitor continuously internal leak condition of power plant valve, the development of a diagnosis and monitoring technique using multi-measuring method should be performed urgently. This study was conducted to estimate the feasibility of multi-measuring method using three different methods such as acoustic emission(AE) method, thermal image measurement and temperature difference$({\Delta}T)$ measurement that are applicable to internal leak diagnosis for the power plant valve. From the experimental results, it was suggested that the multi-measuring method could be an effective way to precisely diagnose and evaluate internal leak situation of valve.

• 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.

• Nuclear Engineering and Technology
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• v.30 no.5
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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.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2019.05a
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• pp.341-342
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• 2019