• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.2
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• pp.191-206
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• 2007

The general theoretical solutions for the wavespeed and damping derived in Part 1 of this work, are incorporated into the computer code. In this paper the code is used in a parametric study of the influence of excitation frequency and variations in material properties on propagation velocity and damping. Compressional wave velocity for waves of the first kind is shown to vary as a function of the frequency-permeability product, with a zone where wavespeed transitions from a lower bound value to a higher bound value with increasing values of the product. Damping is seen to be a maximum where the rate of change in wavespeed is greatest. Waves of the second kind also show a transition in wavespeed from near zero at low values of the frequency-permeability product to an upper bound value at higher values of the product.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.2
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• pp.95-103
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• 2007

An analytical closed-form solution for wave propagation velocity and damping in saturated porous media is presented in this paper The fully coupled field model with compressible solid Brains and pore water were used to derive this solution. An engineering approach for the analysis of fully saturated porous media was adopted and closed-form solutions for one dimensional wave propagation in a homogeneous domain were derived. The solution is highly versatile in that it considers compression of the solid grains, compression of the pore water, deformation of the porous skeleton, and spatial damping and can be used to compute wavespeeds of first and second kind and damping coefficients in various geologic materials. This solution provides a means of analyzing the influence of material property variations on wavespeed and attenuation. In Part 2 of this work the theoretical solution is incorporated into the numerical code and the code is used in a parametric study on wave propagation velocity and damping.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.6
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• pp.803-812
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• 1998

In this study, testing equipment with which several kinds of valves can be tested was composed. Two kinds of tilting check valves and a swing check valve were tested to analyze their dynamic characteristics. The results of the experiment showed that the tilting check valves protected the pump but that the swing check valve could not protect the pump when the reverse flow rate was high. Also the dynamic equation of the tilting check valve was formulated and simulated using system characteristic constant t$_{c}$ and one method of predicting t$_{c}$ by comparing the results of the simulation with the results of the experiment was proposed.sed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.591-595
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• 1997

In analysis of piping vibration of petrochemical plant, the forcing functions mainly depend upon the equipment working mechanism and vibration resources in the piping systems. In general, harmonic function is used for the system with rotary equipments. Mechanical driving frequencies, wave functions, and response spectrum are used for reciprocating compressors, surge vibration of long transfer piping, and seismic/wind vibration, respectively. In this study, for the spray injection case inside the pipe, forcing function was modeled, in which two different fluids are distributed uniformly. To confirm the results, the scheme used for the forcing function was applied for real piping system. The vibration mode of the real system was consistent with the 4th mode obtained by simulation using the forcing function formulated in this study.

• Journal of the Korea Society for Simulation
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• v.10 no.4
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• pp.1-10
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• 2001

For the simulation of piping vibrations in petrochemical plants, forcing functions mainly depend upon the equipment working mechanism and vibration resources in the piping systems. In general, harmonic function is used to simulate rotary equipment. Mechanical driving frequencies, wave functions, and response spectrum are used to simulate reciprocating compressors, surge vibration of long transfer piping, and seismic/wind vibration, respectively. In this study, the general suggestions for forcing functions were reviewed and proposed the forcing function to simulate the spray injection system inside the pipe in which two different fluids are distributed uniformly. To confirm the results, the scheme was applied for a real piping system. The vibration mode of the real system was consistent with the 4th mode (26.725 Hz) obtained by simulation using the forcing function presented in this study.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.235-239
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• 2004

Sound transmission either as airborne or structure borne is a potential problem that occurs in buildings either from sources within or from outside. With the expansion of real estate activities in countries like India, the need to attend sound insulation requirements also assumes greater dimensions. The focus of this research is on studying the sound transmission characteristics of building structures made of hollow blocks, neocrete block, aerocon block and prefabricated panels such as Ferrocement panel. The tests were carried out the blocks with and without plastering and their sound reduction index was measured at one-third octave frequencies. In the case of ferrocement panels, different types of systems were tested in the TL suite. Panels with cavity, with cavity ties, with insulation, with stiffeners and with plasterboard were investigated. Sound reduction index of these panels was measured with additional quantities like longitudinal wavespeed, and loss factors (internal and total loss factor). Tests were also conducted on Cypcrete wall panel and Sandwiched wooden panel in a similar way. Theoretical investigations were carried out using Statistical Energy Analysis (SEA) for the above systems. Sound reduction index was then compared between the predicted and the measured values.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.177-183
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• 2002

The field tests on the waterhammer were carried out in the pump pipeline system with an air chamber. The effects of the input variables and the design parameters for the air chamber were investigated by both the numerical calculations and the experiments. Because the waterhammer problems as a result of the pump power failure were the most important, these situations were carefully studied. Among the input variables used in the waterhammer analysis, the polytropic exponent, the discharge coefficient and the wavespeed had influence on the simulated results in that order, and were calibrated in comparison with the experimental results. As the initial air volume in a vessel increased, the period of waterhammer increased and the pressure variation decreased, resulting from the reduction of the rate of pressure change in the air chamber. Using smaller orifice in the bypass pipe, the pressure rise was suppressed in some degree and the pressure surge was dissipated more rapidly as time passed. The simulations were in fairly good agreement with the measured values until 1∼2 periods of waterhammer. Not only the maximum and minimum pressures in the pipe1ine but also those occurring times were reasonably predicted. The computer program developed in this study will be useful in designing the optimum parameters of an air chamber for the real pump pipeline system.