• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.534-537
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• 2011

This Paper present prediction Vehicle Interior Noise using ATF(Acoustic Transfer Function) and engine radiated sound power. This is useful tool to qualifying the effectiveness of Air-borne noise Path. Furthermore This method provide acoustic package performance of the vehicle and able to prepare frequency band to same segment or benchmarking vehicle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.646-649
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• 2008

This study deals with mechanism of relay operation and modeling of transfer function between impact force and sound pressure due to the impact force in order to reduce relay noise. A collision between a moving-contact and fix-contact produces impact noise. Therefore impact noise of relay is determined by not only excitation force but also transfer function from impact force to noise. In this study, we find mechanism of relay operation, make impact force model and measure characteristic of relay noise. And also we find transfer function of relay noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.356-360
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• 2007

Fuel sloshing in a vehicle fuel tank generates a reluctant low frequency noise, called slosh noise. To reduce slosh noise, whilst many approaches have used the Computational Fluid Dynamics method to first identify fuel behavior in a fuel tank, this paper applies the Transfer Path Analysis method. It is to find contribution of each transfer path from noise transfer function, vibration transfer function and acceleration. Then the final goal is to attenuate slosh noise by controlling them. To this aim, two types of models are studied. One is the decoupled model in which some of connection points of the fuel tank with the vehicle underbody are separated. The other is the modified model which is created by changing noise transfer function and acceleration from the original model. The analysis and validation test results show that the transfer path analysis can be an approach to enhancing slosh noise.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.8
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• pp.766-770
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• 2007

Fuel sloshing in a vehicle fuel tank generates a reluctant low frequency noise, called slosh noise. To reduce slosh noise, whilst many approaches have used the Computational Fluid Dynamics method to first identify fuel behavior in a fuel tank, this paper applies the Transfer Path Analysis method. It is to find contribution of each transfer path from noise transfer function, vibration transfer function and acceleration. Then the final goal is to attenuate slosh noise by controlling them. To this aim, two types of models are studied. One is the decoupled model in which some of connection points of the fuel tank with the vehicle underbody are separated. The other is the modified model which is created by changing noise transfer function and acceleration from the original model. The analysis and validation test results show that the transfer path analysis can be an approach to enhancing slosh noise.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.6
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• pp.803-807
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• 2010

The transfer function method is a widely used in the analysis of underwater radiated noise of ships because it is simple to implement and gives a simple way in the design stage requiring trade-off studies on various kinds of noise sources. In this study, a framework is implemented based on the transfer function method. The framework is interfaced to a software providing transfer functions of hull force to underwater radiated noise. The transfer function-based underwater radiated noise analysis approach is reviewed and the implemented framework structure is described. As an example, a numerical calculation of a virtual ship is carried out and its results are investigated in terms of applicability to real ship design project.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.501-506
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• 2007

Structure-borne noise is the interior noise that results from the low frequency vibrational energy transmitted through those body and joint parts. The relation between the excitation of powertrain and resultant interior sound must be analyzed in order to identify and predict the structure borne noise. The method of acoustic source excitation is preferred than the method of mechanical force excitation to measure the NTF(noise transfer function). Because acoustical method is more convenient and reliable. In this paper, to analysis and identify vehicle interior noise by powertrain is performed, and the vibro-acoustic transfer function is extracted from experimental measurement. These are important step of TPA(transfer path analysis) to identify effect of interior noise resulted from powertrain running excitation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.774-780
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• 2016

In this paper noise source and transfer path of tactical vehicle are analyzed with partial coherence function and spectrum analysis. Engine, transmission, structure panel and aerodynamic are main source of cabin noise. To reduce cabin noise, identifying transfer path of sources and analyzing their contribution is important. With modeling of transfer path and partial coherence function, transfer path and principal noise source can be identified. Engine/transmission and structural resonance are principal source of low frequency noise and by adding stiffener and sound absorbing material, resonance of vibration and inflow air problem can be solved.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.568-574
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• 2012

Turbulent boundary layer noise is already a significant contributor to sonar self noise. For developing acoustic window of sonar system to reduce self noise, a parametric study of design factors of acoustic window is presented. Distance of sensor array from acoustic window, material and damping layer are studied as design factors to influence in the characteristics of the transfer function of self noise. As the result these design factors make change the characteristics of transfer function slightly. Among design factors the location of sensor array is most important parameter in the self noise reduction.

• 대한공업교육학회지
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• v.34 no.1
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• pp.238-251
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• 2009

The noise itself that affects the sensor array is defined as the noise which happens in the place where the system is installed and the circumference noise which comes from the ocean. The array structure for detecting acoustic signal in the underwater effected turbulent layer flow noise. In this paper to design the conformal array spectral density function was introduced and several cases of flow induced noise which affect transfer function were simulated. Modified Corcos wall pressure model was used as turbulent boundary layer flow noise. The effect of noise has been reduced as integrated sum of transfer function has been reduced by decreasing elastomer thickness and density when kx is in low wave number area. Also the characteristics of transfer function by Corcos wall pressure displayed the product of frequency density function. This simulation results can be applied to the conformal array design in unmmaned underwater vehicle in the near future.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.2
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• pp.20-34
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• 2003

The good sea-keeping capability of the SWATH(Small Waterplane Area Twin Hull) ship has been attractive for research or surveillance vessels. Especially, for the naval ships accomplishing the underwater acoustic missions, it is necessary to access and minimize the underwater radiated noise level generated by the ships. Therefore, acoustic signature management and control are very important topics for these vessels. Underwater radiation pattern in the low frequency range is dominated by the tonals from the vibration of onboard machinery. In this work, the radiated noise level generated by the propulsion machine in the submerged hull is predicted using the transfer function technique and the hull transfer function for the submerged hull is determined by analyzing the longitudinal/circumferential stiffened infinitely long cylindrical shell and considering the empirical database of the previous vessels. It is confirmed that the transfer function technique can give useful information for identifying the noise source and estimating its contribution to the total radiatied noise level.