• 한국도로학회논문집
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• 제15권4호
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• pp.75-83
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• 2013

PURPOSES: The purpose of study is to understand the characteristic of driving noise from the front and rear tire for effective active noise cancellation application. METHODS : As literature review, noise measurement methods were reviewed. Noise measurement conducted at three kind of section by road slope using CPX(Close Proximity Method). Noise data was compared by total sound pressure level and 1/3 octave band frequency sound pressure level. Also, each section was compared by T-test using SPSS. RESULTS : In the case of the uphill section, it was shown that the sound pressure level of the front tire at Sugwang-Ri and Sinchon-RI sections was higher than that of the rear tire in low and high frequency band. In the case of high slope section of Sangsaek-Ri, the sound pressure level of the front tire was higher than that of the rear tire in high frequency. Also, in the case of the downhill section, it was shown that the sound pressure level of the front tire at Sugwang-Ri and Sinchon-RI sections was higher than that of the rear tire in low frequency band. However, the sound pressure levels of both the front and rear tires were approximately the same in the high slope section of Sangsaek-Ri. The result of T-test showed that total sound pressures of the front and rear tires were not different from each other in the case of high slope and high speed. CONCLUSIONS: Road slope was not an important variable for effective active noise cancellation.

• 한국소음진동공학회논문집
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• 제17권5호
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• pp.398-404
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• 2007

In this study, the sensitivity of annoyance was investigated by the subjective jury test for the variations of the frequency components along with various sound pressure levels of sixteen environmental noise sources. Annoyance was, also, evaluated for the road traffic noises. Sound pressure levels were $54{\sim}84\;dB$ which individually divided frequency components with eight bands of equally three bark bands. The results show that vehicle traffic noise is recognized as the most serious environment noise source. The sensitivity of human perception of annoyance in frequency bands is quite different from A-weighting curve. The annoyance found out to be more sensitive in high frequency region and reached its maximum in 3.4 kHz.

• 한국도로학회논문집
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• 제15권4호
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• pp.95-105
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• 2013

PURPOSES: The purpose of this study is to research the influence of road traffic noise by road slope through the analysis of the field road traffic noise and determine consideration of road slope in the case of appling active noise cancellation. METHODS: This study measures vehicle's noise by the NCPX method at the three field sections such as uphill, downhill, and flatland. Total sound pressure and sound pressure level by the 1/3 octave band frequency are calculated through the raw field data. Total sound pressure level is compared by ANOVA test and T test statistically. The results obtained are compared in accordance with the road slope and the progress of the uphill section. RESULTS : The noise characteristic of early, medium, and last parts of uphill was found to be consistent when the vehicle was travelling uphill section. The result of statistical test, it was shown that total sound pressures are not different each other. According to the comparison by the geometry, sound pressure of the uphill section was higher than those of the flatland and downhill section in high frequency band. By the result of statistical test, total sound pressure are different according to geometry in the case of high vehicle speed. In the comparison result by road slope, each sound pressure level was found to be consistent in total frequency. However, total sound pressure proportionally increased according to road slope. CONCLUSIONS: It is found that the effect of road slope on noise generation was little in this experimental sites.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.12-18
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• 2014

This paper describes about the development of new concept's rear wheel guards for the reduction of Road Noise in the passenger vehicle using test. The new wheel guards are proposed by various frequency chamber concept and different textile layers concept. Two wheel guards were verified by small cabin resonance test and vehicle test. Through new developing process without vehicle test, Result of road noise will be expected when new concepts and materials of wheel guard is applied into automotive vehicle. As a result of the application of Aimed Helmholtz and Multi-layers concept, this paper classifies the road noise, cost and weight are reduced by new concepts and the solutions are adopted into the 2 cars.

• 한국음향학회지
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• 제37권4호
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• pp.248-255
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• 2018

세단 타입에 비해 해치백 타입의 차량은 실링구조 확보에 어려움이 있기 때문에 후석에서 느껴지는 차폐성능이 열세한 것으로 알려져 있다. 차량의 차폐감 확보를 위해 강건한 실링 시스템과 충분한 흡음/차음 성능이 요구되지만 준중형 이하 세그먼트에서는 원가, 중량의 제약으로 인해 충분한 흡차음 사양 적용에 제한을 받고있어 효율적인 흡차음 사양의 적용이 요구되고 있는 실정이다. 본 연구에서는 정량적인 측정과 비교, 분석이 가능한 파워기반 소음감소(Power Based Noise Reduction, PBNR) 기반의 차음 윈도우 평가를 통해 준중형 해치백 차량의 후석 소음원의 전달 경로를 분석하고 후석 차폐성능 확보를 위한 흡차음 대안을 제시하였다.

• 한국소음진동공학회논문집
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• 제15권8호
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• pp.897-903
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• 2005

When driving on uniformly tining concrete pavement road, the whine noise which has high spectrum at the specific frequency related to the uniform tining space exist. In this paper, a randomization method of tining space for concrete pavements is proposed to reduce the whine noise. The proposed method is developed based on the LCG(linear congruential generator) algorithm. The design parameters used in the method are number of different tining space, ratio of each tining space, total linings of each size. sequence of actual tining under given constant drag length and texture. Monte Carlo simulations are used to validate the proposed method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.770-773
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• 2006

In order to remove the whine noise which has high frequency spectrum related to the uniform tinning space in concrete pavements, randomization study of the tinning space has been done. One of the random tinning space proposed by the authors in the previous study has been applied to the certain region of tile Daegu-Pohang high way construction. In this study, the vehicle interior noise and vibration have been measured in the proposed random tinning road and compared with the data measured in the uniform tinning road. The results show that the magnitude of the peak spectrum is decreased by 18dB(A), and the overall noize level decreased by 4dB(A).

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1735-1740
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• 2000

The aim of this study is to analyze the sound insulation performance of windows depending on the sound source types and to propose the noise control method in the apartment house. The regions where apartment houses are constructed are varied in the dominant noise sources such as aircraft noise, railway noise and road traffic noise. For the experiment, nine noise sources including pink noise were selected and recorded, which was used in the experiment by reproducing. As a result of this study, the sound insulation performance of window was found that when the frequency contents of the noise were high level in all frequency bands the difference of sound insulation performance was negligible, but when the frequency contents were low level at particular frequency band the difference of sound insulation performance was shown very differently.

• 한국음향학회지
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• 제35권4호
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• pp.288-294
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• 2016

타이어와 휠가드 사이의 공간은 타이어 패턴음의 전달경로가 된다. 본 논문에서는 타이어-휠가드 공간에서 발생하는 음향현상을 음장모드 분석과 휠 가드 표면에서 음압분포 가시화를 통해 규명하였다. 타이어 패턴음 저감을 위해 음향학적 댐퍼 역할을 수행하는 캐비티를 휠가드 표면상에 적용하였다. 실내소음은 2 dB(A) 감소하였는데, 본 연구에서 다룬 소음저감방법은 완성차 단계에서 원가/중량의 증가없이 실내음질을 개선하는 효과적인 방안이 될 것이라고 판단된다.

• 한국자동차공학회논문집
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• 제17권1호
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• pp.182-189
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• 2009

The noise from the sunroof can be divided into the low frequency buffeting noise and the high frequency turbulence noise generated when a car runs at the high driving speed. The wind deflector suppresses the buffeting noise generation by accelerating the vortex shedding from the front edge of sunroof opening, and guides the flow direction so that air can pass smoothly over the sunroof opening. To reduce the buffeting noise and the high frequency noise, it is very important to locate a deflector in a proper position depending on the driving speed and the sunroof opening width. The deflector's sectional shape also plays an important role in efficiently reducing the buffeting and high frequency noise. In this paper, we determined the optimum deflector's sectional shape and examined the flow characteristics behind a sunroof deflector through CFD analysis with changing the deflector height, the driving speed and the sunroof opening width. It is found that the deflector needs to be located in the higher location to control the buffeting noise by shedding the higher frequency vortices to accelerating vortices from the sunroof front edge. The deflector may act as a new noise source at the high driving speed, then it is desirable to put the deflector at the proper height to reduce the flow fluctuations and the noise generation. We also made a road test to verify CFD analysis results in this study.