• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.792-796
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• 2013

A practical process to optimize engine mounts on construction equipment is presented in this research. Transmitted force from the engine is estimated by using stiffness of the mount rubber which varies with frequency, amplitude and pre-load, and by the engine excitation force that comes from piston mass and gas pressure and so on. The transmitted force is measured through TPA(Transfer Path Analysis) and is then compared with the estimated force. The optimum mount position and stiffness are solved using MATLAB. The result shows the improvement on engine mount vibration.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.3
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• pp.235-241
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• 2010

Engine Mount plays an important role which supports engine, isolates vibration from engine and blocks the vibration from road. Development of engine mount for NVH costs great a deal. So, the cost of development being reduced, the way developed effectively engine mount using DFSS technique is proposed in this paper. CTQ(critical to quality) is vibration and parameter is dynamic stiffness of mounts. The core parameters are selected with TPA(transfer path analysis) technique. It uses design of experiments(DOE) or Taguchi Methods to optimize parameter values and reduce variation. And then, this paper shows the result of improvement for vibration in the developing vehicle.

• 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

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.11
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• pp.1206-1212
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• 2008

This paper presents a the method for estimating the noise source contribution on the road noise of the vehicle in a multiple input system where the input sources may be coherent with each other. By coherence function method, it is found that the biggest part of the noise source in the road noise is generated by structural vibration on the mechanical-acoustic transfer functions of vehicles. This analysis is modeled as four input/single output system because the noise is generated with four wheels that mechanism of the road noise is very complicated. The coherence function method is proved to be useful tool for identifying of noise source. The overall levels of the interior noise be coherence function method are compared with those measured and calculated by the frequency response function approach using mechanical excitation test. The experimental results have shown a good agreement with the results calculated by the coherence function method when the input sources are coherent strongly each other. The estimation of the road noise indicates that significant coherent can be achieved in the vehicle interior noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.208-214
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• 2000

Reduction of structure-borne noise of the compartment in a car is an important task in automotive engineering. Transfer path analysis using vibroacoustic reciprocity technique or multiple path decomposition method has generally been used for structure-borne noise path analysis. These methods are useful in solving particular problem but do not quantify the effectiveness of vibration isolation of each isolator of a vehicle. To quantify the effectiveness of vibration isolation, the vibrational power flow has been used for a simple isolation system or a laboratory based isolation system. It is often difficult to apply the vibrational power flow technique to the complex isolation system like a car. In this paper, a simple equation is derived for calculation of the vibrational power flow of an isolation system with multiple isolators such as a car. It is successfully applied to not only quantifying the relative contributions of eighteen isolators but also reducing structure-borne noise of a passenger car. According to the results, the main contributor of eighteen isolators is the rear roll mount of an engine. The reduced structure-borne noise level is about 5dBA.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.854-859
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• 1994

As powertrain noise is better and better controlled, road noise inputs become more important. The interior road noise of a car is mainly induced by the wheels rolling over the road surface. Each of the four wheels act as an independent and uncorrelated excitation input. To rank the energy transfer form each input to the interior, a Transfer Path Analysis (TPA) needs to be made-which requires operational vibration measurements. However due to the multiple uncorrelated inputs, phase relations vary continuously. It is therefore necessary to separate the operational data into set of "independent phenomena" by means of a Principal Component Analysis (PCA). A TPA can then be carried out for each independent phenomenon. Operational deflection shapes referenced to these principal components share the physical phenomena. The details of the methodology are discussed and a discussion of the results on a car shows that the method gives accurate results for full vehicle testing.e testing.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.779-784
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• 2008

This paper presents a the method for estimating the noise source contribution on the road noise of the vehicle in a multiple input system where the input sources may be coherent with each other. By coherence function method, it is found that the biggest part of the noise source in the road noise is generated by structural vibration on the mechanical-acoustic transfer functions of vehicles. This analysis is modeled as four input/single output system because the noise is generated with four wheels that mechanism of the road noise is very complicated. The coherence function method is proved to be useful tool for identifying of noise source. The overall levels of the interior noise be coherence function method are compared with those measured and calculated by the frequency response function approach using mechanical excitation test. The experimental results have shown a good agreement with the results calculated by the coherence function method when the input sources are coherent strongly each other. The estimation of the road noise indicates that significant coherent can be achieved in the vehicle interior noise.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.3
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• pp.184-190
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• 2015

NVH engineering has become a hot issue due to radical technology changes and development in automotive industry since customers' expectations and needs for their vehicle is taken to a higher level. However, the source identification and quantification of the road noise within a vehicle is still not at the level where it needs to be to meet their expectations due to its' complex transfer path and difficulties in path optimization. The primary focus of this research is on direct force obtaining method at suspension hard points using suspension test rig. Directly obtained forces at suspension to body mounting points are critical and crucial for determining the effects of design changes of the suspension has on road noise performance. Direct force obtaining method has its limitation in sensor installation within an actual vehicle therefore, many has been indirectly calculating forces using full matrix inversion method or dynamic stiffness method. In this study, to circumvent this limitation, a suspension rig is used. Then, the suspension rig is verified through a comparative analysis of its dynamic behavior between the actual vehicle by cleat test on chassis dynamometer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.3
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• pp.17-24
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• 1999

This paper presents a method of ANC for transfonrer noise control utilizing a sproker and microphone pair. In this study, the main focus is on identifying the dynamic characteristics of speaker - amplifier microphone path. This study presents a theoretical method to identify the dynamic characteristics of speaker-microphone pairs. The transfer functions of microphone - speaker pair have been estimated utilizing sequential least square(SLS) algorithm. We identified the estimated transfer function has stable JXlles and zeros in z-plane. This paper also propose an architecture far the noise cancellation to which we applied the estimated transfer function.nction.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.1
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• pp.97-103
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• 2016

The sensitivity of interior noise that the passengers perceive is comparatively high in the train, and structure-borne and air-borne types of noises come into the train. In this paper, to analyze contributions of these noise sources operational transfer path analysis(OTPA) is used. OTPA has some advantages of executing the contribution rates of several sources simultaneously, and in this work, 29 points are measured while running. Transfer functions between reference measurement points and response measurement points are calculated by the singular value decomposition(SVD) and Principal component analysis(PCA) method, and the frequency characteristics of the noise source are successfully derived. Also the interior noise is predicted and compared with measurement data to show the reliability.