• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1720-1725
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• 2008

Because of the continuous increasing of energy consumption, metallic pipelines are widely used to supply services to customers such as gas, oil, water, etc. Most common metallic pipelines are underground and are now frequently being installed in nearby electric power lines. In recent years, buried gas pipeline close to power lines can be subjected to hazardous induction effects, especially during single line to ground faults. because it can cause corrosion and it poses a threat to the safety of workers responsible for maintenance. Accordingly, it is necessary to take into consideration for analysis of induced voltage on gas pipelines in transmission lines. This paper analyzed the induced voltage on the gas pipelines due to the 154kV transmission lines in normal case and in different faulty case conditions using EMTP (Electro-Magnetic Transients Program).

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.1
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• pp.92-99
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• 1998

Unsteady flow problems created by hydraulic transients in pipeline systems with pump are of significant importance because they can cause excessive pressure, cavitation, vibration and noise. In this paper, an analysis of transient flow for the pump pipelines is developed by means of the characteristic method. The calculated results of the program to simulate water hammer due to sudden valve closure in a simple pipeline are compared with those of the analytical method. Expecially the water hammer due to power failure in pump pipeline system with surge tank was simulated. As the results, both the upsurge and the downsurge along the pipeline are reduced.

• Journal of Mechanical Science and Technology
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• v.20 no.3
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• pp.426-434
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• 2006

The impact of leakage was incorporated into the transfer functions of the complex head and discharge. The impedance transfer functions for the various leaking pipeline systems were also derived. Hydraulic transients could be efficiently analyzed by the developed method. The simulation of normalized pressure variation using the method of characteristics and the impulse response method shows good agreement to the condition of turbulent flow. The leak calibration could be performed by incorporation of the impulse response method with Genetic Algorithm (GA) and Harmony Search (HS). The objective functions for the leakage detection can be made using the pressure-head response at the valve, or the pressure-head or the flow response at a certain point of the pipeline located upstream from the valve. The proposed method is not constrained by the Courant number to control the numerical dissipation of the method of characteristics. The limitations associated with the discreteness of the pipeline system in the inverse transient analysis can be neglected in the proposed method.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.85-91
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• 2008

The deviation of measured pressures in pipeline networks from normal or reference pressures is useful information for judging the operation of the pipeline networks. A cost-effective monitoring of pipeline networks including a leak detection capability can be realized when transient pressure variation is accurately predicted using measured conditions at supply- and demand-sides of the networks. In this study, a pipeline network analysis program was developed based on one-dimensional flow equations for compressible fluids. The validity of the present analysis was demonstrated by simulating the flow in a straight pipeline and comparing the results with the previously reported ones. Pressure and flow rate transients in several simple city-gas pipeline networks were also analyzed to show the usefulness of the developed program.

• International Journal of Fluid Machinery and Systems
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• v.8 no.1
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• pp.55-62
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• 2015

This study aims to present a hydraulic transitory study as MOC applications for solving the Saint-Venant equations in two case studies: 1) in a penstock of a small hydropower system as a simple pipeline in the case of valve-closure in the downstream boundary with a reservoir in the upstream boundary; and 2) for discharge propagation into a channel by velocity and depth of the flow channel along space evaluation. The proposed methodology by Chaudry [5] concerning the development of hydrodynamic models was used. The obtained results for first and second case study has been confirmed that MOC numerical approach is useful for several engineering purposes, including cases of hydraulic transients and discharge propagation in hydraulic systems.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.269-277
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• 2009

The current paper focuses on the analysis of transient cavitating flow in pressurised polyethylene pipes, which are characterized by viscoelastic rheological behaviour. A hydraulic transient solver that describes fluid transients in plastic pipes has been developed. This solver incorporates the description of dynamic effects related to the energy dissipation (unsteady friction), the rheological mechanical behaviour of the viscoelastic pipe and the cavitating pipe flow. The Discrete Vapour Cavity Model (DVCM) and the Discrete Gas Cavity Model (DGCM) have been used to describe transient cavitating flow. Such models assume that discrete air cavities are formed in fixed sections of the pipeline and consider a constant wave speed in pipe reaches between these cavities. The cavity dimension (and pressure) is allowed to grow and collapse according to the mass conservation principle. An extensive experimental programme has been carried out in an experimental set-up composed of high-density polyethylene (HDPE) pipes, assembled at Instituto Superior T$\acute{e}$cnico of Lisbon, Portugal. The experimental facility is composed of a single pipeline with a total length of 203 m and inner diameter of 44 mm. The creep function of HDPE pipes was determined by using an inverse model based on transient pressure data collected during experimental runs without cavitating flow. Transient tests were carried out by the fast closure of the ball valves located at downstream end of the pipeline for the non-cavitating flow and at upstream for the cavitating flow. Once the rheological behaviour of HDPE pipes were known, computational simulations have been run in order to describe the hydraulic behaviour of the system for the cavitating pipe flow. The calibrated transient solver is capable of accurately describing the attenuation, dispersion and shape of observed transient pressures. The effects related to the viscoelasticity of HDPE pipes and to the occurrence of vapour pressures during the transient event are discussed.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.69.2-69.2
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• 2013

The direct detection of gravitational wave has a very important meaning as a basis for verification of the theory of relativity. Several laser interferometer detectors have attempted to detect GW directly (e.g. LIGO, VIRGO), but positional accuracy of GW detector is too wide (about 10~100sq deg) to find which objects emit GW. One of the main sources of GW is gamma-ray burst which can be detected even in electromagnetic wave. Then to verify Gamma-ray burst object as a GW source, we proceed EM follow-up observation with wide field of view. A first program initiating EM follow-ups to possible transients GW events has been developed and exercised by LIGO and VIRGO community in association with several partners. Using QUEST optical data, we tested the method of cross-convolution recommended by EM follow-up community. We will describe the results of that test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.12 s.243
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• pp.1574-1585
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• 2005

In this paper, a spectral element model is developed for the uniform straight pipelines conveying internal unsteady fluid. Four coupled pipe-dynamics equations are derived first by using the Hamilton's principle and the principles of fluid mechanics. The transverse displacement, the axial displacement, the fluid pressure and the fluid velocity are all considered as the dependent variables. The coupled pipe-dynamics equations are then linearized about the steady state values of the fluid pressure and velocity. As the final step, the spectral element model represented by the exact dynamic stiffness matrix, which is often called spectral element matrix, is formulated by using the frequency-domain solutions of the linearized pipe-dynamics equations. The FFT-based spectral dynamic analyses are conducted to evaluate the accuracy of the present spectral element model and also to investigate the structural dynamic characteristics and the internal fluid transients of an example pipeline system.

• Proceedings of KOSOMES biannual meeting
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• 2009.06a
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• pp.177-178
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• 2009

Hydraulic Transients would be occurred since pressure is increased or decreased when water speed inside of pipeline is rapidly changed A study on water hammer has become more important because the pumping stations were big and the systems conveying the fluid through the large and long transmission pipelines were complex. In this study, the method of characteristic line was adopted to evaluate the valve-induced water hammer phenomena in a pumps feedwater system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.925-928
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• 2005

In this paper, a spectral element model is developed for the uniform straight pipelines conveying internal unsteady fluid. The spectral element matrix is formulated by using the exact frequency-domain solutions of the pipe-dynamics equations. The spectral element dynamic analyses are then conducted to evaluate the accuracy of the present spectral element model and to investigate the vibration characteristics and internal fluid transients of an example pipeline system.