• Journal of the Korean Institute of Gas
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• v.8 no.2 s.23
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• pp.54-60
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• 2004

In this paper, the maximum von Mises stress and maximum displacement of the corner protection and secondary bottom structures have been analyzed using a finite element analysis technique. The design criterion of the comer protection is 1,500Pa for a normal nitrogen gas purging process at the beginning stage of start-up procedure. This pressure is very safe for the structure safety of the comer protection and secondary bottom plates. The corner protection and secondary bottom plates fabricated by $9\%$ nickel steel sheet may plastically be distorted and fractured for the increased gas pressure of 8,475Pa, which produces the maximum von Mises stress of 833MPa and maximum displacement of 1.9m at the center of secondary bottom plate.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.104-108
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• 2018

Experimental studies have been done to examine the aging characteristics by regulator diaphragms of gas pressure, governor room of city gas. Various testing samples with different service periods were manufactured. The results of SEM observation indicated that the surface and thickness of the samples tested were slightly sensitive to the service periods. It was found that as the service periods increased, the tensile strength of diaphragm samples decreased. For samples over 25 years of service, the strength decreased to approximately 60 % of that of new diaphragms. It was also found that as the service periods increased, the elongation increased.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.17 no.1
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• pp.8-17
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• 2021

The seat leakage test is required after the maintenance work on the valve seat. Either the test has been performed outside of the plant after cutting the valve from the pipe system or the simplified test has been performed so far. It was unable to perform the test at the plant site because it is hard to make a steady pressure on the valve inlet when it is installed in the pipe. This research aims to perform the leakage test in the nuclear power plant while it is installed in the pipe system. The mock-up test is performed by pressurizing the leak-off pipe on the valve body. The result is compared with traditional test result by pressurizing the valve inlet. Furthermore the chamber mock-up tests are performed under various conditions. The leak rate by the developed test using the leak-off pipe is found to be similar but greater than the leak rate by the existing test method. It implies that the test using the leak-off pipe is more conservative than the existing test. The methodology and the equipment which this paper suggests that on-site seat test is possible and the application of the technology could reduce the time and cost for the valve maintenance work significantly.

• Fire Science and Engineering
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• v.12 no.4
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• pp.21-30
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• 1998

The safety of LPG vessel storage has been simply designed and controled with blast wave barrier structure concept regardless of its quantity or hazardous situation. The limit of regal controls on LPG vessel storage need to be identified in terms of safety buffer distance from LPG explosion. The level of overpressure effect and heat radiation to the neighbouring structure and human activity required to be estimated to find the gap between existing controls on such storage. PHAST and IAEA manual for risk rankings and assessment had been applied to get the required safety distance for neighbouring facilities, Japanese legal control for such facilities were also investigated. To this context the issues on LPG vessel storage required additional safety distance between existing blast wave barrier structure and safety separation distances.

• Korean Journal of Dental Materials
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• v.45 no.4
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• pp.275-286
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• 2018

The purpose of this study was to evaluate the effect of needle tip design and position, and irrigant flow rate on apical pressure (AP) during root canal irrigation. Five human mandibular premolars were instrumented up to #35 (0.06 taper) using nickel-titanium rotary instruments. Three different needles according to change of needle tip design (notched, side-vented, and flat) were positioned at the point of 1, 3, and 5 mm from the apical constriction (needle tip position). For each needle tip design and position, APs were measured with varying flow rates of 0.05, 0.1, 0.2, and 0.3 ml/s. When the other conditions were controlled, AP increased with decreasing needle tip position or increasing irrigant flow rate (p<0.05). The AP of flat needle was the highest, followed by notched, side-vented needle for the same needle tip position and irrigant flow rate. The APs at needle tip position of 1 mm or with more than 0.1 ml/s flow rate were higher than central venous pressure (5.88 mmHg) for all conditions. Flat needle was not recommended for clinical use due to sharp increase of AP with changing needle tip position and irrigant flow rate. For safe and effective root canal irrigation, irrigant should be applied with the needle tip position of 3 mm and flow rate of less than 0.05 ml/s.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.49-56
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• 2012

Rupture disks are a kind of safety device in high pressure equipment and they are used to control rupture pressure in the solid rocket motor. In this paper, a series of rupture experiments was performed using rupture disks made of AISI 316L and rupture pressure of rupture disks was calculated through various assumptions in relation between elasto-plastic material properties and true stress-strain curve. Experiment and FEA indicated rupture pressure is determined by size of rupture disks. As a result of elasto-plastic analysis, only multi-linear stress-strain curve was able to calculate meaningful estimations. Experimental results also showed rupture location are decided by the size of rupture disks. Experimental and FEA results will be applied to control rupture pressure of disks.

• The Korean Journal of Applied Statistics
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• v.29 no.7
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• pp.1385-1398
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• 2016

A pressurizer is a major equipment system in a nuclear power plant (NPP) and controls the reactor cooling system pressure within the allowable range. Faults in the pressurizer can be critical to the NPP; therefore, early fault detection in the pressurizer is significant for NPP safety. This study applies Mahalanobis Taguchi system (MTS), which is one of the promising pattern classification methods, based on the Mahalanobis distance concept and Taguchi quality engineering theory to the early fault detection problem of the pressurizer pressure control system. We conducted experiments using data from full scope NPP simulator based on a pressurizer pressure transmitter faults scenario to validate the faults detection performance of MTS. As a result, MTS can rapidly detect the faults compared to conventional faults detection based on single sensor monitoring.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.146-149
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• 2014

Compared to Butane tank, the propane tank should have a higher compressive strength due to its higher vapor pressure. In this study, a theoretical analysis was performed to evaluate the effect of change in the geometry of bottom plate on the mechanical property of tank, and an experiment was also carried out to observe the propensity of the deformation and failure of the vessel using hydraulic pressurizing device. The compressive strength of the vessel was observed to improve 1.5-2.5 MPa as the curvature of the bottom plate was decreased 62 mm and the thickness of the bottom plate was increased 0.25 mm. This study are expected to provide viable information conducive to achieve on-going development of a small vessel for the pressurized propane gas.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.4
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• pp.393-401
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• 2002

Pipelines in power plants, nuclear facilities and chemical industries are often affected by corrosion effects. It is important to inspect the internal defects in pipelines in oder to guarantee safe operational condition. We have taken relatively much time, cost and manpower to use conventional NDT methods because these methods are contact measuring methods. In this paper, we used digital shearography, a laser-based optical method which allows full-field measurement of surface displacement derivatives. This method has many advantages in practical use, such as low sensitivity to environmental noise, simple optical configuration and real time measurement. The experiment was performed with pressure vessels which has different internal cracks and detected internal cracks in the pressure vessels at a real time using phase shifting method.

• Fire Science and Engineering
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• v.24 no.3
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• pp.139-144
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• 2010

Recently, evacuation safety of building resident become the major concern, as the building has been higher and more complicated. Many high-rise multi use buildings are under construction in Korea. Required evacuation time using stairway is longer in high-rise buildings, moreover it is impossible for the disabled to evacuate by using stairway. For this reason the study on the effectiveness of using elevator for evacuation is progressing. This study shows the pressure change in various types of hoistway when elevator is moving. Experiments were performed in 4 different types of hoistway, and showed big difference in pressure change between the type of hoistway. The pressure change in single hoistway that have one car is bigger than that in multi hoistway that have multi cars. The results of this study can be used for the study of elevator piston effect as basic data.