• International Journal of Automotive Technology
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• 제8권1호
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• pp.67-73
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• 2007

This study analyzes the interior noise that is generated during acceleration of a passenger car in terms of car body structure and panel contribution. According to the transfer method, interior noise is classified into structure-borne noise and air-borne noise. Structure-borne noise is generated when the engine's vibration energy, an excitation source, is transferred to the car body through the engine mount and the driving system and the panel of the car body vibrates. When structure-borne noise resonates in the acoustic cavity of the car interior, acute booming noise is generated. This study describes plans for improving the car body structure and the panel form through a cause analysis of frequency ranges where the sound pressure level of the rear seat relative to the front seat is high. To this end, an analysis of the correlation between body attachment stiffness and acoustic sensitivity as well as a panel sensitive component analysis were conducted through a structural sound field coupled analysis. Through this study, via research on improving the car body structure in terms of reducing rear seat noise, stable performance improvement and light weight design before the proto-car stage can be realized. Reduction of the development period and test car stage is also anticipated.

• 대한음성학회지:말소리
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• 제48호
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• pp.141-153
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• 2003

Researches into robust recognition in noise environments, especially in car environments, are being carried out actively in speech community. In this paper we will report on three types of corpora that SiTEC (Speech Information TEchnology & industry promotion Center) has created for research into speech recognition in car noise environments. The first is the recordings of 900 Korean native speakers, distributed according to gender, age, and region, who uttered application words in car environments. The second is the collections of mixed noise in 3 car types by model while setting up various noise patterns which can be obtained with the car engine on or off, at different driving speed, and in different road conditions with windows open or closed. The third is the recordings of simulated speech by HATS (Head and Torso Simulator) in car environments with the internal and external noise factors added. These three types of recordings were all made through synchronized 8 channel microphones that are fixed in a car. The creation and applications of these corpora will be reported on in detail.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.447-453
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• 2009

The interior noise of the High Speed Train(HST) is analyzed by applying the statistical energy analysis (SEA) method. The interior of each vehicle is divided lengthwise into nine cavities. Since the rolling noise and aerodynamics noise are expected to be dominant noise sources, they are treated as the noise sources in the model. To further simplify the model, curtains and seats are excluded. The simulation runs involving one-car, three-car and five-car trains are conducted. The maximum predicted noise level is 98.4dB. The results also show that the predicted noise levels are within 0.23% of each other. The results imply that it is not necessary to estimate the interior noise of the train by constructing multiple-car train models. The noise estimate based on just one-car train can be optimal with respect to the computational effort and modeling time.

• 대한산업공학회지
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• 제42권1호
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• pp.73-79
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• 2016

The purpose of this study is to understand human sensory and emotional response according to car noise. This study investigated human stress levels from car noise based on the data of electro-encephalogram (EEG) and subjective evaluation analysis data. Since there are few previous works on the effect of car noise on human's reaction, more profound research about the effect of car noise on driver's emotion would be worth performing. Subjects were exposed to five different kinds of car noises. EEG data were collected while the subject was exposed to noise. In order to process EEG data, FFT analysis was used to separate the collected EEG data into ${\alpha}$-wave and ${\beta}$-wave. Also, survey was performed to carry out subjective evaluation. The results of the subjective evaluation were closely correlated to those found in the EEG signal analysis. The results from this study may provide useful information for mitigating car noise induced stress.

• 한국소음진동공학회논문집
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• 제24권11호
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• pp.854-860
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• 2014

Workers engaged in car inspection works have been exposed to many occupational hazards including noise, particulate matter, and volatile organic substances. Noise-induced hearing loss(NIHL) is one of the leading health hazards among Korean workers. The aim of this study is to evaluate the noise levels in several car inspection shops by introducing the evaluation methods of KMOEL/OSHA and ACGIH. Six sites in central area of Korea were selected to monitor the noise levels of workers by personal and area sampling methods for two consecutive days in spring, summer, fall and winter seasons. Dosimeters have been used for this noise monitoring program. Obtained noise levels by the evaluation method according to KMOEL/OSHA are the range of 50.2~88.2 dB(A), these are lower than KOEL/OSHA standards level of 90 dB(A). But highest noise by ACGIH's evaluation methodology is recorded 92.3 dB(A) and is greater than NIHL standard level of 85 dB(A). So that many workers may be exposed to the dangerous noise environment. The higher the car inspection loads daily, the higher the noise levels in the sites. Seasonal fluctuation of noise levels at the process might give monitoring results with high variations. Area noise levels showed higher than those of personal sampling, which illustrate some high noise spots in the car inspection areas.

• 소음진동
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• 제9권5호
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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.

• 소음진동
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• 제8권4호
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• pp.706-714
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• 1998

The purpose of this study is to analyse the main factors and attributes of psychological evaluation to noise. For this purpose, a psycho-acustic experiment was conducted by using the method of rating scale. 52 subjects were participated in the experiment, 20 stimuli were presented to subjects in random order with 23 adjectives. As a result of factor analysis, it was found that the primary factors for evaluating the quality of noise subjectively are four factors of unpleasantness, intensity, irregularity, and sharpness. And, as a result of MDPREF(multi-dimensional analysis of preference data), it was found that the noise sources including the factors of unpleasantness, intensity, and irregularity are related to the sounds of hammering in construction field, car horn, road traffic, idling of car, and printing by computer printer, and the factor of sharpness are the sounds of car siren, claps of thunder, car horn, and snowstorm etc.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.591-592
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• 2007

• 대한음성학회:학술대회논문집
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• 대한음성학회 2004년도 춘계 학술대회 발표논문집
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• pp.231-234
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• 2004

This paper describes an efficient method for improving the noise-robustness in speech recognition in a running car by considering wind noise. In driving car, mainly three kind of noises engine noise, tire noise and wind noise, are severely affect recognition performance. Especially wind noise is an important factor in driving car with window opened. We analyzed wind noise in various driving conditions that are 60, 80, 100 km/h with window fully opened, window half opened. We clarified that the recognition rate is significantly degenerated when the wind noise components in the frequency range above 200 Hz are large. We developed a preprocessing method to improve the noise robustness despite of wind noise. We adaptively changed the cutoff frequency of the front-end high-pass filter from 100 through 200 Hz according to the level of the wind noise components. By this method, the recognition rate is considerably improved for all kind of driving conditions

• 항공우주시스템공학회지
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• 제4권2호
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• pp.10-15
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• 2010

Aerodynamic noise is becoming the major source of annoyance for modern cars recently and is caused by many different noise sources in a car. Appropriate CFD technologies, therefore, have been developed to resolve the noise problems related with aerodynamics. It is necessary for designers to fully understand the relationship between vehicle aerodynamics and wind noise acoustics. In this study, we simulate the flow fields around two different shapes of side mirror models of passenger car and analyze the noise phenomena around one side mirror model that has lower drag than the other model using Fluent 6.3.