• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.298-304
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• 2012

The development of low rolling resistance tire with weight reduction in tire and vehicle may induce high level of tire/road noise, especially the rumble road noise on rough road. In this paper, the design factor for good rumble noise is considered in view of tire and vehicle. For the 3 mid-sized sedans, the rumble noise is very sensitive to the test vehicle. And it is concluded that the tire with high tread part stiffness and low sidewall part stiffness shows best rumble noise performance, and the rumble noise is in trade-off relation with cavity resonance noise. So, it is desirable to select and change proper construction design factors to have good tire/vehicle rumble noise.

• International Journal of Highway Engineering
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• v.15 no.3
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• pp.31-36
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• 2013

PURPOSES: This study is to investigate a generated traffic noise when vehicle pass over a transverse rumble strip at toll plaza of highway. METHODS: To investigate traffic noise at toll plaza of highway, Pass-by method which is the most common used for measuring traffic noise was adopted and the traffic noise at toll plaza was measured for 10 min per hour for 11hours(13:00~24:00). RESULTS: The measured traffic noise by pass-by method was changed as function of the transverse rumble strip configuration. Generally, the maximum difference among three noise measurement sections was 7 dB(A). It might be related with traffic speed. Also, the measured traffic noise was strongly generated from a passenger car which was 2 axle. It means that the most of traffic noise on the road is generated at tire/pavement interface of the passenger car. CONCLUSIONS: The traffic noise was strongly related with vehicle speed and transverse rumble strip configuration on the road. For driver safety, the transverse rumble strip is definitely necessary. However, the complaints from residents near highway was increased by traffic noise from transverse rumble strip. Therefore, To satisfy both safety and reduction of traffic noise, the development of configuration of transverse rumble strip is necessary in the further study.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.201-206
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• 2012

PURPOSES: This study evaluated a measuring technique for tire-pavement interaction noise that uses a noble close proximity (NCPX) method as well as for noise level measured inside of a car (e.g., Inside Noise Level) in term of rumble strips constructed at a tall gate. METHODS: According to the measurements of NCPX and inside noise level (INL), 1/3 octave band frequency analysis and overall noise level calculation were conducted in order to evaluate noise levels of NCPX and INL, depending on types of rumble strips. RESULTS: The tested sections of general concrete pavement surface and two different types of rumble strips were evaluated, using 1/3 octave band frequency analysis and overall noise level. From the analyzed results, it can be concluded that rumble strips generate a relatively huge noise levels when compared to the concrete pavement surface. CONCLUSIONS: Noting that above 3 dBA different noise levels can let drivers know that they are getting close to toll gate; therefore, they should apply their brakes. Thus, the noise levels of rumble strips are required to be reduced, based on considering the neighbors living near toll gates.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.77-88
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• 1993

This paper shows the methods about an improvement of the sound quality, which is improvement for automobil market recently. Especially, the rumble noise in the passenger compartment makes driver uncomfortable. For an improvement of the rumble noise, in this paper, the increase of the number of balance weight of the crank shaft(from 4 to 8), the vibration constrainer of cylinder block and the flexible flywheel were applied to power plant. Among those kinds of applications, the application of the flexible flywheel to power plant makes not only the vibration of the engine mount boss reduce most effectly but also the interior noise. It also improves the sound quality and the rumble noise disappears in the passenger compartment.

• International Journal of Highway Engineering
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• v.15 no.6
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• pp.33-39
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• 2013

PURPOSES : This research investigates traffic noise characteristics as change the transverse rumble strips shape from rectangular to cylinder at toll plaza of highway. METHODS : The traffic noise was investigated at two different places at toll plaza of highway. One is modified grooving, another is employed cylinder shape of TRS instead of rectangular shape of TRS. A measurement of traffic noise was conducted at same location and time period. The traffic volume information was gotten from office of highway office and vehicle speed was measured by speed measuring device. The traffic noise measurement was conducted from 13:00 to 23:00 and by pass-by method. Also, the traffic noise was measured behind noise barrier. Various distance from noise barrier(7.5m, 30m, 50m) and different heights(1.2m, 3m, and 5m) were parameter for measurement of traffic noise in this study. RESULTS : The class 1 vehicle was contributed from traffic volume which was increased 1,500. However, the distribution of traffic speed didn't change compare to previous investigated period. From this study, It was found that the external traffic noise was changed as function of geometric shape of TRS. The external noise from modified grooving was less than 1.2dB(A) of the current TRS. A difference of traffic noise was 20dB(A) before and after barrier. It came from a noise barrier effect as reduction of traffic noise. According to investigate a traffic noise distribution near barrier, there is similar noise characteristic as function of height at 7.5m distance from noise barrier. Also, There is no different traffic noise between 30m and 50m from source of the noise of sound barrier. CONCLUSIONS : Based on this traffic noise investigation result, there is a clear characteristic difference as changed TRS shape. The traffic noise was reduced by changed TRS shape. Specially, traffic noise was decreased although the traffic volume was increase for same investigation time and period. It is implied that cylinder type of TRS significantly reduces the traffic noise. The specification of various TRS will be studied in the future.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.177-186
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• 2009

Rumble strip was introduced in highway pavement for driver's safety in Korea on 2000. With proving its effectiveness, total length of highway with rumble strip has increased. This research team suggested a modified form of the existing rumble strip, which was placed on new concrete pavement during construction. The modified construction equipment was applied on test section at PyungTeak-Eumsung highway with some performance experiments. Through the equation of stopping sight distance proposed AASHTO, the modified form is safer than the existing one due to 0.65m of extra width. The indoor noise test showed that the modified form $3.5{\sim}9dB(A)$ noisier than the main pavement, which wasn't applied by rumble method. Therefore, it was one of alternatives to prevent sleeping. The modified form made the frequency effected on man's eye. There were no differences of the noise and vibration between modified form and existing one. However, that driver who participated on operating test on that section felt that the former was safer than the latter. It can be concluded that modified form can be applied to the new concrete pavement, that will decrease traffic accident.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.377-382
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• 2003

In our previous study, we have developed sound quality index for steady rumbling sound of passenger car. In this paper, we will study sound quality index for transient rumbling noise. The subjective evaluation of rumbling sound can be indicated to objective parameters by sound metrics of psychoacoustics and principal rumble component. And artificial neural network can be estimated complexity and nonlinear characteristics of relation between subjective evaluation and sound metrics. We applied to sound metrics and artificial neural network to development of sound quality index for transient rumbling sound of passenger car.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.833-834
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• 2012

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.621-622
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• 2013

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.957-961
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• 2005

A satellite component must withstand vibration caused when launch vehicle acoustics and engine rumble transfer to it through its structural mount. Components shall be subjected to environmental tests after manufacturing process thus the environmental test conditions are needed for component level test including vibration and shock. This paper deals with derivation of component-level environmental test specifications, especially for solar panels of STSAT-2(Science & Technology SATellite-2). Sine sweep random vibration, and shock test conditions were generated for solar panels by assuming the satellite as single-degree-of-freedom system with a base excitation.