• Journal of Advanced Marine Engineering and Technology
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• 제22권5호
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• pp.635-642
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• 1998

In automobile exhaust system. Internal pressure pulsation and shell vibration greatly affect the surface sound radiation. This noise is emitted from the muffler outer shell due to the pulsation of the exhaust gas pressure. This paper describes an analytical study of these characteristics as influenced by exhaust system structure. An exhaust simulator was used for generating the pressure pulsation. The relationship between shell vibration and radiated noise was used for generating the pressure pulsation. The relationship between shell vibration and radiated noise was identified by finding FRF.

• 한국자동차공학회논문집
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• 제4권3호
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• pp.40-49
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• 1996

With the advance of the standard of living, the demand on automobile goes beyond the simple transportion equipment, therefore the interior noise reduction has been the important factor for improvement of the ride quality. Idling noise is a major vehicle characteristic determining occupant comfort. In the present research two approaches for noise source identification based on theory for multi-input system have been investigated. The concept of the frequency response function and the multi-dimensional spectral analysis were used to estimated the spectra of the noise source.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.217-222
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• 2006

Internal combustion engine is the main source of environmental pollutants and therefore advanced technology is required to reduce harmful elements from the exhaust gases all over the world. Especially, when the exhaust gas is released front the automotive muffler, exhaust noise has many bad influence on the surrounding environment. In order to reduce the exhaust noise, it is necessary that automotive muffler must be designed for best exhaust efficiency. The sound insulation room was installed for the analysis of an acoustics characteristics of the noise from automotive muffler, in this study. Exhaust gas noise, noise distribution characteristics, pressure and temperature of exhaust gas were investigated with the change of annulus temperature of air cooled annulus automotive muffler and cooled annulus automotive muffler. The following results were obtained with this study. From the frequency analysis of automotive muffler, high noise distribution was observed in the range $100{\sim}2000Hz$. It means that the noise in this range has an dominate influence for the overall noise. Noise reduction of automotive muffler was affected by the temperature of annulus. It is caused the result that the high temperature and pressure of exhaust gas are changed lower by the drop of annulus temperature. The tendencies of noise, the temperature and pressure of exhaust gas are similar to the performance curve of engine. Exhaust gas pressure is determined by the r.p.m. of engine and affected by the cooling performance of automotive muffler.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.680-685
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• 2006

The latest trend in the automotive industry demands the development of high stiffness car bodies and the securement of inter-system performance for low vibration and noise vehicles. This demand, however, conflicts with need for light weight design and greater fuel efficiency, thus raising the importance of optimization design to satisfy both developmental goals. We chose two European medium sedans, which has gasoline engine and diesel one, to elucidate the noise characteristics of diesel passenger cars, whose sales have been increasing in both Korea and Europe. In the present study a systematic experiment was conducted to analyze the noise characteristics in diesel cars. we made it possible for differentiating car management according to customer demand while allowing for improved commercial feasibility. it was possible to improve interior noise by 2 dB(A) on average sound pressure level. As a result, by 4% higher on articulation index(AI).

• 한국자동차공학회논문집
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• 제2권6호
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• pp.29-37
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• 1994

Active noise control of random noise which propatate in the vehicle cabin as a form of spherical wave is the target of this study. In the previous study, the adaptive algorithm for adaptive controller is presented for the application in active noise control system. And for the preliminary study of adaptive active noise control in vehicle cabin as a real system, a computer simulation is performed on the effectiveness of the adaptive algorithm in the amplitude of the pressure fluctuation. This work studies the implementation of multi-channel feedforward adaptive algorithm for the reduction of the noise inside a vehicle cabin using a number of secondary sources derived by adaptive filtering of reference noise source. Multi-channel adaptive feedforward algorithm are verified in numerical simulation and semi-experimental justification of developed system is made on a domestic passenger car. In the results of semi-experimental study, the noise of specific region in the interior of automobile are reduced for the appreciabe sound pressure level in the operating engine rpm and finally this study suggests the capabilities of the real time active noise control in 3 dimensional acoustic fields.

• 전자공학회논문지
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• 제54권6호
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• pp.117-122
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• 2017

전기자동차 파워트레인에서 발생되는 소음은 주로 모터의 전자기력 불균형에서 오는 소음과 기어 장치의 기계 시스템에서 발생되는 소음으로 구분될 수 있다. 이 소음들은 일반적 연소 엔진음 보다는 작지만, 조용한 배경 소음 때문에 더 거슬리는 소리가 될 수 있음에도 불구하고 그 소음의 특성이나 저감 방법은 널리 알려져 있지 않다. 본 논문에서는 전기차 개발단계 혹은 완성단계에서 적용할 수 있는 전달 경로에 감쇠 수동형 패치를 부착하여 소음을 저감하는 방법을 제시하고자 한다. 먼저, 모터 소음은 모터의 동적 특성에 따라 영향을 받으며 또한 모터 토크와 어떠한 상관성을 가지는 지를 보여준다. 또한, 모터 보다는 감속기의 표면이 더 소음에 취약한 부위라는 사실을 실험적으로 보여준다. 마지막으로, 주요 소음 전달경로인 드라이브 샤프트나 감속기 하우징 표면에 패치를 부착하여 실차 평가하였으며 실험 결과는 가속보다는 감속 조건에서 소음이 저감되는 영향이 크다는 것을 보여준다.

• 한국산학기술학회논문지
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• 제20권3호
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• pp.570-575
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• 2019

능동 머플러는 자동차 머플러의 배기소음을 저감하기 위하여 능동 소음 제어 기법을 적용하여 구현된다. 기존의 보편적인 Filtered_x LMS 알고리즘은 음향 궤환이 존재할 경우 제어필터의 차수가 매우 커지고 수렴성이 악화되는 문제가 있다. 이를 보완할 수 있는 Recursive LMS 알고리즘은 적응필터의 적응과정에서 쉽게 발산할 수 있어 적용이 제한되어 왔다. 본 논문에서는 수렴 성능과 계산량 부담이 개선되도록 1차 경로와 2차 경로 전달함수의 구조를 IIR 필터로 설계하였으며 IIR 필터 구조의 단점인 안정성 확보를 위해 안정화 필터 알고리즘을 적용하였다. 안정화 필터 알고리즘은 적응과정 중에 음향 궤환에 해당하는 전달함수의 극점이 발산하는 것을 방지하기 위하여 극점을 단위원 내부로 끌어 당기는 역할을 수행한다. 이러한 방법으로 능동 머플러 시스템의 계산량 절감과 수렴성능을 향상시킬 수 있다. 제안한 시스템의 유용성을 보이기 위하여 가변 환경인 디젤 엔진의 배기음향을 대상으로 기존의 Filtered_x LMS 알고리즘과 제안한 시스템과의 성능을 비교하여 그 우수성을 보였으며, 계산량은 절반 이하, 수렴 특성은 4배 이상의 성능을 보였다.