• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.4
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• pp.18-26
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• 1996

Based on experimental analysis, the characteristics of pulsating pressure wave propagation is clarified by testing of 4-stroke gasoline engine. The pulsating pressure wave in exhaust system is generated by pulsating gas flow due to working of exhaust valve. The pulsating pressure wave is closely concerned to the loss of engine power according to back pressure and exhaust noise. It is difficult to exactly calculate pulsating pressure wave propagation in exhaust system because of nonlinear effect. Therefore, in the first step for solving these problems, this paper contains experimental model and analysis method which are applied two-port network analysis. Also, it shows coherence function, frequency response function, back pressure, and gradient of temperature in exhaust system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.72-78
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• 1996

Based on experimental analysis, the characteristics of pulsating pressure wave propagation is clarified by testing of 4-stroke gasoline engine. The pulsating pressure wave in exhaust system is generated gyulsating gas flow due the working of exhaust valve. The pulsating pressure wave is closely concerned to the loss of engine power according to back pressure and exhaust noise. It is difficult to exactly calculate pulsating pressure wave nonlinear effect. Therefore, in the first step for solving these problems, this paper contains experimental model and analysis method which are applied two-port network analysis. Also, it shows coherence function, frequency response function. back pressure, and gradient of temperature in exhaust system.

• Ocean and Polar Research
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• v.31 no.4
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• pp.389-399
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• 2009

Subsurface pressure gauge has many advantages in measuring a wide range of wave spectra in coastal waters from wind waves to long waves. However, a shortcoming of the gauge is related to the difficulties in recovering surface wave spectra from subsurface pressure records. In this study, the effect of current on the pressure transfer function of the pressure gauge, and hence on the surface wave energy spectrum, was investigated by analyzing the subsurface pressure data based on the linear wave theory. For this purpose, laboratory experiments were carried out in a wave-current flume. Subsurface pressure records, as well as the surface elevation data, were obtained simultaneously under different wave and current conditions. Pressure transfer functions were obtained and compared with those estimated from the linear wave theory, both with and without inclusion of the current-effect. It was established that wave spectra obtained from subsurface pressure gauge were in closer agreement with those from surface wave gauge when current-effect on the pressure transfer function was taken into consideration for analysis.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.1
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• pp.77-84
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• 1998

Based on experimental analysis, the characteristics of pulsating pressure wave propagation is clarified by testing of 4-stroke gasoline engine. The pulsating pressure wave in exhaust system is generated by pulsating gas flow due to working of exhaust valve. The pulsating pressure wave is closely concerned to the loss of engine power according to back pressure and exhaust noise. It is difficult to exactly calculate pulsating pressure wave propagation in exhaust system because of nonlinear effect. Therefore, in the first step for solving these problems, this paper contains experimental model and analysis method which are applied two-port network analysis. Also, it shows coherence function, frequency response function, back pressure, and gradient of temperature in exhaust system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.244-245
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• 2014

Recently, the studies on submerged breakwater are increased due to needs considering the quality of water and the scenic view. In this paper, waves coming to permeable submerged breakwater coming with oblique angle are computed numerically by using wave pressure function. The wave pressure function throughout the analytical region including the fluid and submerged breakwaters is used. An unknown quantity expressed by the wave pressure function is simulated by boundary element method. The maximum reflection coefficient shows the tendency of decrease with the increase of oblique angle and The reflection coefficient shows the tendency of increase with the increase of the values of the linear dissipation coefficient and the added mass coefficient. It is means that the reflection coefficients are strongly dependent on the oblique angle and resistance coefficients.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.6
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• pp.422-432
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• 2013

A System Identification method to develop parametric models linking free surface elevation and wave pressure is presented and two models are built allowing for either wave pressure or free surface elevation simulation. Linear, time invariant model structures with static nonlinearities are assumed and solutions are sought in a form of autoregressive model with extra input (ARX). An arbitrary chosen free-surface elevation and wave pressure dataset is used for estimation of the models, which are subsequently verified against datasets with similar pressure gauge depth but different free-surface elevation spectra due to different meteorological conditions. It is shown that free-surface simulation using System Identification methods can perform better than traditional linear transfer function derived from linear wave theory (LTF), while wave pressure simulation quality using presented methods is generally similar to that obtained with corrected LTF.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.149-153
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• 2005

In the cardiovascular system, the waveform of the pulsatory blood pressure appears variously due to the cardiac impulse and compliance of blood vessels and arm tissue. We have constructed a blood pressure simulator to investigate effects of mechanical properties of artery walls and tissue on blood pressure measurements. The blood pressure simulator is designed to reproduce wave forms of blood pressure in human arteries. To minimize tracking error, we use a linear control valve, and adapt a hybrid control scheme which consists of a feedback controller and a feedforward controller. Any form of the pressure wave can be reproduced, changing function of the wave form in the computer connected to the simulator for control. From experiments, it has been shown that the simulator reproduces wave forms very well, and that the hybrid scheme adapted is superior to the feedback controller.

• Journal of computational fluids engineering
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• v.19 no.3
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• pp.8-13
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• 2014

In this study, wave characteristics coming with oblique incident angle to permeable trapezoidal submerged breakwater on the porous seabed are calculated by using boundary element method. This numerical analysis, based on the wave pressure function, is analyzing the continuity in the analytical region including fluid and structure. From the comparison of the reflection coefficients and damping coefficient, the results of this study are in good agreement with the existing results. The peak values of reflection coefficient obtained by permeable trapezoidal submerged breakwater on the porous seabed are smaller than those of permeable trapezoidal submerged breakwater on the non-porous seabed. The velocity vector in front of permeable trapezoidal submerged breakwater on the porous seabed is smaller than that in front of permeable trapezoidal submerged breakwater on the non-porous seabed with out the energy loss.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.275-276
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• 2013

This analysis method is based on the wave pressure function with the continuity in the analytical region including fluid and porous structures. Wave profiles coming with oblique angle to permeable submerged breakwater on the porous seabed are computed numerically by using boundary element method. When compared with the existing results for the oblique incident wave, the results of this study show good agreement. The results indicate that wave profiles own high dependability regarding the change of oblique incident waves and permeable submerged breakwater on the porous seabed. Therefore, the analysis method of this study are estimated to be applied as an accurate numerical analysis referring to oblique incident waves and permeable submerged breakwater on the porous seabed in real sea environment.

• Journal of Navigation and Port Research
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• v.37 no.3
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• pp.283-289
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• 2013

Wave profiles coming with oblique angle to trapezoidal submerged breakwater on the porous seabed are computed numerically by using a boundary element method. The analysis method is based on the wave pressure function with the continuity in the analytical region including fluid and structure. When compared with the existing results on the oblique incident wave, the results of this study show good agreement. The fluctuation of wave profiles is increased in the rear of the submerged breakwater due to the increase of the transmission coefficient, as the incident angle increases. In addition, in the case of the wave profiles passing over the submerged breakwater on porous seabed, it is able to verify that the attenuation of wave height occurs more significantly due to the wave energy dissipation than that of passing over the submerged breakwater on the impermeable seabed. The results indicate that wave profile own high dependability regarding the change of oblique incident waves and porous seabed. Therefore, the results of this study are estimated to be applied as an accurate numerical analysis referring to oblique incident waves and porous seabed in real sea environment.