• Proceedings of the KSME Conference
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• 2001.06a
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• pp.871-876
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• 2001

One-touch fittings are important components that can make a quick and tight connection between pneumatic pipe systems. In this study, the stress analyses with various working pressures on these one-touch fittings are carried out using finite element method. Material properties, to use the stress analyses, are measured by the universal tester and digital Vickers hardness tester. The stress analyses on the circular shell spring forced by various pressures(100, 150, 200, 250kpa) and on the main body due to the fluid-structural interaction are investigated. Results show that the stresses of one-touch fitting are concentrated to supported part of main body and the soundness of a circular shell spring with maximum pressure 250kpa was confirmed.

• Fire Science and Engineering
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• v.30 no.3
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• pp.55-61
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• 2016

In this study, to determine whether it is possible to apply Polyethylene (PE) compound pipe, which was developed to solve the problem caused by the corrosion of the fire protection piping currently in usein water based fire extinguishing systems, we performed an actual mockup fire test. Since no test standard was available related to the developed compound pipe, we compared and analyzed domestic and international technical materials and test standards and selected suitable fire test standards to evaluate the performance of the PE compound pipe. we applied two fire test standards to the PE compound pipe, viz. those for CPVC and metallic pipes, and conducted a total of 6 experiments to evaluate its performance. According to the results of the first and second fire tests based on the test standard for the CPVC pipe, neither the fitting nor the piping was damaged or deformed and no leakage was observed in the pressure test, which was performed for 5 minutes. For the fire test based on the metallic pipe test standard, a total of 4 experiments were conducted. The first two experiments were conducted to simulate the wet piping system. In the results of this fire test, neither leakage nor rupture was observed from the PE compound pipe and no damage was caused, such as the secession of the PE material. However, in the next two experiments, which simulated the dry system, the PE compound pipe suffered damage and rupture, including deformation before the fire fighting water was discharged. Therefore, we found that the piping performance of the PE compound pipe did not undergo any deterioration, including fusion, deformation, or damage, in the wet piping system simulated fire test.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.234-239
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• 2003

A cylindrical shape object is widely used as a mechanical part and a water pipe or an oil pipeline which are of cylindrical shape are widely used in the infrastructure. In order to handling such objects automatically using a robot, the posture i.e. orientation in 3D space should be recognized. However, since there is no edge or vertex in the pipe, it is very difficult task for the robot. In this paper in order to guide the robot, two kind of algorithms which find the axis using the measured range data from the robot to the object surface are to be developed. The algorithms are verified using both the simulated range data and the measured one.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.337-345
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• 2009

This paper investigates the reliability of district heating pipes at thermo-elastic fatigue loading. District heating pipes, subjected to $120^{\circ}C$ and $16kg_f/cm^2$ due to water distributing service through inside the pipes, should endure long term cyclic thermal-mechanical loadings. The heating pipes are the co-centric tubes of steel pipe, poly urethane(PUR) insulator, and high density poly ethylene(HDPE) case. On installation, foam pad is externally wrapped for accommodating stress reduction near the bend sections of pipes. However, there have been frequent reports on the failures of bend sections in the middle of long term service. This study scrutinizes the observed failures near the bend sections through applying the finite element methods. Specially in this study, heating pipes are studied on the influence of foam padding on failures and proposed new designs for reinforced bend without foam pad.

• Corrosion Science and Technology
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• v.20 no.6
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• pp.403-411
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• 2021

In this study, the reliability of a commercial ER-type corrosion sensor was evaluated under an accelerated corrosion environment to verify its suitability for application in monitoring of ship's seawater piping system. A closed-loop pump piping testbed was designed and constructed to compare the wall thickness reduction of the pipe and the response from the sensor. The sensor was attached inside the pipe near the outlet of the pump that was exposed to a 3.5% NaCl solution with or without copper accelerated acetic acid (CASS). The results demonstrated that the presence of CASS significantly increased the corrosivity of the solution as well as the thickness reduction of the pipe, as expected. On the other hand, the corrosion products formed by the solution with CASS were thicker compared with those without CASS. The sensor response to temperature variation was found to be a clear linear relationship for the solution without CASS but there was a non-linear relationship where CASS was present.

• Fire Science and Engineering
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• v.31 no.4
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• pp.86-94
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• 2017

In the present study, a Cook Book method and a Static System Analysis method were compared with each other on the basis of a seismic design criteria of fire-fighting facilities and analyzed. The Cook Book method is analyzed by dividing a pipeline in each same section. In this method, a stress analysis is not possible except for the section analyzed in such a way that a brace is designed according to the weight of pipe, water and pipe fitting. To the contrary, in case of the Static System Analysis method, the stress analysis for the whole pipeline can be performed because the whole pipeline is regarded as a single structure. For the fatal stress values locally generated, it is necessary to actively perform a pipeline analysis by installing a device capable of locally relieving the stress of the pipeline. In Korea, only the Cook Book method is provided as the seismic design criteria of fire-fighting facilities, which causes many problems with diversification of seismic design. Thus, it is necessary to apply the seismic design method of the pipeline by using various kinds of engineered Static System Analysis methods.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.101-106
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• 2012

The press bulging process is very useful and productive method to produce round-type mechanical components which have not been able to be manufactured because of limitation of the conventional press technology. The application of the press bulging process has expanded very quickly in the hydraulic and electronic industry and more recently it has been used to produce other mechanical parts such as the automobile and shipping parts. This expanding application also has brought some unsolved problems and leads many researchers to put their effort into the die design of the press bulging process. In this study, to obtain the optimum die shape for the press bulging process, various process parameters have been considered such as corner radius, bulging height, pressing length, and forming load, etc. The main interest of this paper is to verify the press bulging process which has more than 4.0 in height-length ratio. From this aspect, Finite Element analysis shows great ability to simulate the precise deformation process and gives us manufacturing database. Consideration of strain, stress, and strain-rate for the various cases has been also taken to keep the forming load within a particular range.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4763-4768
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• 2014

Recently, aluminum pipes have been used instead of steel pipes for open and shut machines in vinyl housing because of its corrosion-resistance and light weight. In particular, the light weight is very useful for fitting and removal by human resources. On the other hand, an aluminum pipe is weak in winter because aluminum has a larger thermal expansion coefficient than steel. This study examined the freezing and bursting of aluminum pipes by numerical analysis. The mechanical-thermal deformation characteristics were analyzed under the condition of ice volumetric expansion in aluminum pipes reaching 50%. From numerical analysis, large stresses above the yield stress occurred in aluminum pipe after ice expanded in the net diameter immediately. In addition, the freezing and bursting of aluminum pipes was predicted around an ice volumetric expansion of 6 - 7% because the thickness of the aluminum pipe reached an aluminum elongation ratio of 17%. Therefore, it is recommended that aluminum pipes be sealed perfectly to prevent water flow in the pipe. These results suggest that it is very difficult to prevent freezing and bursting of aluminum pipes by water freezing in the pipe.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.10
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• pp.1219-1230
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• 2004

Comparing to the gravimetric and volumetric method, the flowmeter calibration based on the master meter method is relatively economical and convenient, especially for high flowrate. The uncertainty of flow quantity and flowrate using the master meter method was evaluated according to the GUM (Guide to the Expression of Uncertainty in Measurement). In order to apply for the wider flow range, two master meters (electromagnetic flow meter) were employed as reference flowmeters. The uncertainty of the master meter was obtained by combining the statistical variation of the repeated measurements and the variation of fluid density and pipe material due to temperature and pressure changes were scrutinized. for a practical application, the uncertainty of calibrator, whose measuring capacity of 1000 ㎥/h obtained by employing two 500 ㎥/h electromagnetic How meters, was evaluated. The uncertainty budget shows the quantitative contribution of each uncertainty component to the overall uncertainty of the calibrator. As a result, it was found that the dominant uncertainties were from the master meter, which was evaluated statistically, and from the process of least squares fitting. On the contrary, the uncertainties arising from the variation of the fluid density and the pipe volume due to the temperature and pressure were negligible.

• Fire Science and Engineering
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• v.24 no.6
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• pp.89-97
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• 2010

In recent fire protection system, the pipings should be light weighted, seismic proof and wrought with non-welding method. The light weighted stainless steel pipes and fittings, satisfying these requirements, are already used as a fire protection system in Germany, Netherland, Taiwan, Australia, United States and Japan. Accordingly, performance evaluation tests were carried out to determine whether or not the fittings can be used in the pipings. As the performance evaluation tests, we conducted vibration test, water hammering test, bending test and fire test. With the results of the tests, we concluded that the fittings can be used in the fire protection system, and that the life expectancy of the fittings exceeds that of buildings.