• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.191-194
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• 2005

Recently the heavy weight impact noise transmitted slab vibration has been recognized as an important issue. The aim of this study is to find the path of vibration transmission, comparing the numerical analysis with the field test results. Additionally the effect of stiffening beam element under slab, as a method to increase the stiffness of slab, will be shown concerning natural frequencies.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.767-770
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• 2006

To predict vibrational energy density of simple structural-acoustic coupled systems in medium-to-high frequency ranges, Power Flow Finite Element Method(PFFEM) is used, and PFFEM sofiware, PFADS has been developed for the vibration predictions and analysis of coupled system structures in medium-to-high frequency ranges. However, it needs to consider vibro-acoustic coupled analysis to get more accurate results. Prior to implement vibro-acoustic coupled analysis functions in PFADS, research on vibro-acoustic coupled analysis using PFFEH is performed for simple models. These predictions include the indirect transmission path associated, and also the direct transmission path, and the formulation is extended to structural system model by using appropriate modifications to structural-acoustic and acoustic-acoustic joint matrices. Concerning the waves in plate and acoustic, it is possible to calculate the structural-acoustic full matrix of a model using PFFEM, and the formulations developed are implemented for two rooms surrounded by plates.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.8
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• pp.805-815
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• 2008

Transfer path analysis(TPA) and panel contribution analysis(PCA) have been used widely to reduce interior noise of mechanical systems. TPA enables us to decompose interior noise into air-borne and structure-borne noises and estimate the path contribution of noise sources. PCA is also used to identify the noise contribution of each sub-panel in vibro-acoustic systems. In this paper, TPA and PCA are applied to wheel loader, one of the heavy construction equipments. Firstly, TPA for air-borne noise is conducted to estimate the contribution of air-borne sources using pressure transfer function. Thereafter, TPA for structure -borne noise is employed to verify the results of air-borne source quantification through the synthesis of two results. Secondly, PCA is performed by both TPA using pressure transfer function between panels inside the cabin and boundry element method(BEM) for the cabin of wheel loader with various boundary conditions. As a results, it was found that TPA conducted by experiments and PCA accomplished by both experiments and BEM are very effective methods in analyzing the path and contribution of the noises for reducing an interior noise level in the wheel loader system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.439-440
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• 2012

New analysis methods complement classical approaches in the vehicle NVH development by reducing and accelerating iteration steps to obtain a target sound. Therefore, tools are required that allow an integrative approach of sound engineering and structural analysis and enable a precise simulation and modification based on measured data. The Response Modification Analysis (RMA) is such a hybrid solution, which provides indications of relevant transfer paths taking into account the sensitivity of response channels to modifications of reference channels.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.02a
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• pp.10-15
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• 2000

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.6 s.111
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• pp.582-592
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• 2006

This paper presents experimental and analytic methods to reduce interior noise generated by car axle. The test vehicle has a whine noise problem at passenger seats. In order to identify transfer path of interior axle noise, the vibration path analysis, the modal analysis and running modal analysis are systematically employed. By using these various methods, it has been founded that the interior noise generated by car axle was air borne noise. To reduce and predict axle noise, various structural modifications are performed by using FEM and BEM techniques, respectively. Through the modification of the axle structure, the air borne noise of the axle was reduced 3$\sim$4 dBA level.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.648-649
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.594-595
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• 2012

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.613-614
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• 2013

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.2
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• pp.176-184
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• 2013

Quantification of road noise is a challenging issue in the development of tire noise since its transfer paths are complicated. In this paper, a simplified model to estimate the road noise is developed. Transfer path of the model is from wheel to interior. The method uses the wheel excitation force estimated throughout inverse method. In inversion procedure, the Tikhonov regularization method is used to reduce the inversion error. To estimate the wheel excitation force, the vibration of knuckle is measured and transfer function between knuckle and wheel center is also measured. The wheel excitation force is estimated by using the measured knuckle vibration and the inversed transfer function. Finally interior noise due to wheel force is estimated by multiplying wheel excitation force in the vibro-acoustic transfer function. This vibro-acoustic transfer function is obtained throughout measurement. The proposed method is validated by using cleat excitation method. Finally, it is applied to the estimation of interior noise of the vehicle with different types of tires during driving test.