• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1488-1493
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• 2004

The purpose of the present work is to develop a compressed air discharging system to eject a projectile from the underwater. For the flow analysis of compressed air tank, projectile ejection tube, and pipe system, the air is assumed as an ideal gas, undergoing 1-dimensional axisymmetric, compressible flow, the Fanno flow analysis was applied. The commercial Fluent code was used to solve 3-D Navier-Stokes equation of the internal flow within the valve. The dynamics of the projectile within the ejection tube was assumed 1-degree of freedom. The calculations were performed to four cases of valve opening area ratio, i.e., 25%, 50%, 75%, and 100% opening area, at both depths of 10m and 50m. The results were shown as the figures of time variation of pressure of the compressed air tank and projectile ejection tube. The velocity and distance of the projectile were also predicted.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1070-1072
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• 2003

In this paper, Firstly, it is shown that the high vibration source of piping system is the pulsation transmission of pipe line element ,such as, orifice plate, valves and the control valve is a broad band source and the branch wall and the cavity have vortex frequency Secondly, in order to decrese the turbulence vibration of piping system, the practical analysis of piping flow by EFD have been developed and its effectiveness is investigated as applying it at piping system practically.

• Journal of computational fluids engineering
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• v.14 no.1
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• pp.35-44
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• 2009

To adequately analyze flows in pipe or duct network system, traditional node-based junction coupling methods require the junction loss which is specified by empirical or analytic correlations. In this paper, a new finite volume junction coupling method using a ghost junction cell is developed by considering the interchange of linear momentum as well as the important wall-effect at junction without requiring any correlation on the junction loss. Also, boundary treatment is modified to preserve the stagnation enthalpy across boundaries, such as pipe-end and the interface between junction and branch. Also, the computational accuracy and efficiency of the Godunov-type finite volume schemes are investigated by tracing the total mechanical energy of rapid transients due to sudden closure of valve at downstream end.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.3
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• pp.230-237
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• 2020

In order to design a diesel engine system and predict its performance, it is necessary to analyze the gas flow of the intake and exhaust system. A gas flow analysis in three-dimensional (3D) format needs a high-resolution workstation and enormous time for analysis. Therefore, the method of characteristics (MOC) was used for a gas flow analysis with a fast calculation time and a low-resolution workstation. An experiment was conducted on a single cylinder diesel engine to measure pressure in cylinder, intake pipe and exhaust pipe. The one-dimensional (1D) gas flow was analyzed under the same conditions as the experiment. The engine speed, valve timing and compression ratio were the same conditions and the intake pressure was inputted as the experimental results. Bent pipe such as an exhaust port that cannot be realized in 1D was omitted. As results of validation, the cylinder pressure showed accuracy, but the exhaust pipe pressure exhibited inaccuracy. This is considered as an error caused by the failure to implement a bent pipe such as an exhaust port. When analyzed in 3D, calculation time required 61 hours more based on a model of this study. In the future, we intend to implement a bent pipe that cannot be realized in 1D using 3D and prepare a method to supplement reliability by using 1D-3D coupling.

• Journal of Energy Engineering
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• v.7 no.2
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• pp.202-208
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• 1998

As in the other industrial processes, a nuclear power plant involves a steam relieving process through which condensable steam is discharged and condensed in a subcooled pool. An analysis of steam discharge transients was carried out using the method of characteristics to determine the flow characteristics and dynamic loads of piping that are used for structural design of the piping and its supports. The analysis included not only the steam flow rate but also the flow rates of the air and water which originally exist in the pipe. The analytical model was developed for a uniform pipe with friction through which the flow was discharged into a suppression pool. Including the combinations of system elements such as reservoir, valve and branching pipe lines. The piping flow characteristics and dynamic loads were calculated by varying system pressure, pipe length, and submergence depth. It was found that the dynamic load, water clearing time and water clearing velocity at the water/air interface were dependent not only on the system pressure and temperature but also on the pipe length and submergence depth.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.69-74
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• 1999

Upland Irrigation Network Analysis System(UINAS) used Object-Oriented Programming (OOP). The results of using OOP is definition of objects and class hierarchy for UINAS, Objects of UINAS are consist of the Pipe , Sprinkler, Valve , Pump, Tee , Bend and Contractions. The classj hierarchy have cooperative design for FEM in analysing the irrigation network. Therefore UINAS have a flexiblility in additioning the network components.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.1
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• pp.114-122
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• 2018

In this paper, we propose new water pressure measurement system to measure the water pressure of water pipe laid underground beneath the manhole efficiently. For this purpose, we installed water pressure sensor(IoT) which has built-in bluetooth module at valve of water pipe. The proposed system can be managed through collected data which measured at sensor and then transmitted to smart phone through bluetooth connectivity and re-transmitted to server on this system. By checking out water pressure data stored in server from remote location, the persons in charge can confirm the leakage of water pipe or propriety of water pressure in management area. By this procedure, they can detect the existence of condition of water pipe and manage water pressure of water pipe efficiently.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.19-24
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• 2004

A great deal of exhaust gas inside a combustion room goes out through exhaust pipe but residual gas, is called 'Blow by gas', enters the crankcase through a small gap between the piston and the cylinder wall. Here, if the crankcase isn't vented, this causes many bad effects such as lubricant oil contamination, corrosion by that and crankcase explosion by rising pressure. So most automobiles are constituted with a PCV(Positive Crankcase Ventilation) system to prevent previous problems. PCV valve is the most important part in this ventilation system. When companies are manufacturing new cases, engineers are designing it depending on their experiments than theoretical knowledges. Much efforts and times are needed for new development. This study will show quantitative results to increase the possibilities.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.4
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• pp.66-73
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• 2005

A great deal of exhaust gas inside a combustion room goes out through exhaust pipe. But residual gas 'Blowby gas' enters the crankcase through a small gap between the piston and the cylinder wall. Here, if the blowby gas isn't vented, this causes many bad efffcts such as lubricant oil contamination, corrosion by that and crankcase explosion by rising pressure. So most automobiles are constituted with a PCV(Positive Crankcase Ventilation) system to prevent previous problems. PCV valve is the most important part in this ventilation system. When companies are manufacturing new cases, engineers are designing it depending on their experiments than theoretical knowledges. Much efforts and times are needed for new development. This study will show quantitative results to increase the possibilities for the optimal design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.569-576
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• 2002

A case history is presented pertaining to piping fatigue by vibrations and sustain stresses in the hydraulic oil supply system for control valves in a 200MW thermal power plant that ultimately resulted in pipe rupture. The Piping was designed to supply the hydraulic oil for turbine control valves. Testing and analyses were performed on the system to develop solution to repair work on failures.