• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.623-624
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• 2009

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.203-208
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• 2002

In order to reduce the booming noise caused by first bending mode of a drive shaft, this paper proposes a simulation program for prediction of the bending mode frequency of any tubular shaft. This program consists of a pre-processor for modeling of geometrical shape of the drive shaft with boundary conditions of various joints, a processor for constructing of global finite element matrices using beam elements and an eigen-solver based on MATLAB program. Using this simulation program, the effective and accurate FE model far a shaft attached to vehicle can be obtained by aid of database for stiffness of each joint. Thus the resonance frequencies and mode shapes of a shaft can be calculated accurately. Because the effect of the resonance on interior noise can be verified, more improved shaft will be proposed at the early stage of design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.10a
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• pp.282-287
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• 1994

본 연구에서는 연구대상 차량의 소음저감 방안을 마련하기 위하여 차체의 진동 및 차실의 음향 특성해석, 연성해석을 수행하였다. 차실 음향특성을 나타내는 음향모드는 유한요소 해석으로부터 결정하였다. 이때 해석결과를 확인하기 위하여 음향모드를 측정, 수치해석결과와 비교하였다. 차실소음의 가진 특성을 갖는 차체의 진동특성은 모드시험을 통해서 결정하였다. 결정된 이들 모드들의 연성해석은 연성해석 전용 컴퓨터 프로그램을 사용하여 수행하였고, 그 결과를 소음실험 결과와 비교하여 Booming 소음에 기여가 큰 차체 panel부위를 결정하였다. 기여가 큰 panel의 진동특성 변경시 소음효과를 측정하여 구조변경 방안을 검토하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.1009-1012
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• 2004

Recently, the concern on sound qualify (SQ) is on the steep increase in the fields of vehicle and home appliance and over the fast few decades a considerable number of studies have been conducted on SQ evaluation. As a result, basic procedure for SQ evaluation has been already suggested. Although most interesting sounds have time-varying features, however, little is known about their SQ evaluation. The purpose of this study is to systematize a method for SQ evaluation of non-stationary sound. For this, various listening tests procedure for non-stationary sound is introduced and it is attempted to find out correlation between various SQ metrics and subjective data obtain from listening test. Booming of car interior noise in acceleration is used as an example and finally, representative value is obtained for the interesting sensation of non-stationary sound.

• International Journal of Safety
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• v.7 no.1
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• pp.5-9
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• 2008

For the purpose of controlling the coupling between the car body panels and passenger compartment, experimental investigation of an acoustic cavity with an air gap is carried out to reveal how the air gap influences the acoustic modal characteristics of the cavity. The acoustic modal characteristics of the cavity is closely related with the booming noise. The experimental results show that a very small air gap can change the acoustic modal characteristics of the cavity and, as a result, the air gap can be an important factor in controlling the booming noise for comfortable and safe passenger compartment.

• International Journal of Safety
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• v.5 no.1
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• pp.17-23
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• 2006

An investigation was carried out to determine the effect of the thickness of the air-gap installed between the roof metal sheet and the headliner on booming noise in passenger cars. In addition, a way of offering quieter driving condition to drivers and passengers was studied. It was found that a very thin air-gap corresponding to approximately 3/100 of the height of the passenger compartment causes noticeable change in the coupled resonance frequencies and acoustic responses. Furthermore, a guideline is proposed for determining an optimal air-gap thickness during design stage of the air-gap beneath the roof metal sheet for reducing booming noise.

• Journal of KSNVE
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• v.9 no.5
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• pp.998-1004
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• 1999

The passenger car manufacturer should meet more and more strict requirements of customers on noise and vibration problems. It is proven that the Taguchi method is a powerful tool for improving the product quality in many areas. This paper employs the Taguchi method to reduce low-frequency booming noise in a passenger car. Selection of object function is very important to minimize interaction effects in the Taguchi method. We select logarithmic-scaled sound pressure level as an object function, which is commonly used to analyze the noise and vibration signals. The optimum noise level predicted with additive-model assumption agrees well with the test results. In addition, the optimum level is lower than the initial one by about 5 dB without any adverse effects. The results show that the Taguchi method can be applied efficiently to solve the noise problem in the passenger cars.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.12
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• pp.106-113
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• 1997

While driving, the low frequency interior noise below 200Hz causes the main component that irritates the auditory acoustic sense. But these passive control methods bring out increment in cost and weight of the vehicle and result in low efficiency. Recently, various ANC(Active Noise Control) methos to suppress the low frequency noise began to launch into application. In this study, we implemented the active noise control system for passenger vehicle to cancel the engine booming noise using DSP-based control unit, 4 micorphones, and 2 speakers. We used MEFX-LMS (Multiple Error Filtered X-Least Mean Square) algorithm since it can be easily implemented in real time. Also, MEFX-RLS algorithm was taken to enhance the suppression of the harmonic components of the engine booming noise inspite of its computational complexity. The performance of two adaptive algorithms were analyzed with experimental resutls.

• Journal of KSNVE
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• v.10 no.3
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• pp.480-485
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• 2000

This paper presents the application of the substrctural analysis based on the frequency responses for the prediction of the interior noise in a car. The complex trimmed body with the high modal density is presented by the experimental data. Finite element model presents the powertrain and its subframes with the lower modal density. The substructural analysis based on the frequency responses combines the frequency response functions from the numerical analysis and the experiments. It describes the interior noise successwfully. Using this method we can pick up the most dominant paths for the booming noise and predict the effects of the design changes easily.

• Journal of KSNVE
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• v.9 no.4
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• pp.785-794
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• 1999

The panel contribution analysis to reduce interior booming noise of a passenger car is carried out using both experimental method and numerical one. The accelerations of panels are measured on the outer surface of car body during operation. The acoustic characteristic of cavity is represented by two different ways. One is the acoustic transfer function obtained by experiment with reciprocal manner. The other is the boundary element model and numerical results of the model are calculated using SYSNOISE. The results from numerical method show more good agreement with measured sound pressure levels than the experimental one. Contributions of panels for interior noise are ranked and structure of the car is reinforced according to the results, which shows that the panel contribution analysis is a powerful tool to lessen structure-borne noise of passenger vehicle.