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박상일 ( Sang Ill Park ),최형일 ( Hyung Il Choi ),정경훈 ( Kyung Hoon Cheong ),정원삼 ( Won Sam Jeong ),김난희 ( Nan Hee Kim ),이종국 ( Jong Kuk Lee ),오남승 ( Nam Seung Oh ) 조선대학교 공학기술연구원 2008 공학기술논문지 Vol.1 No.2
Quantitative evaluation for the sound source to predict the noise in the field point for the Road Traffic Noise was conducted. The traffic noise level and frequency characteristics as per types of cars for wave process until the noise reaches the field point was measured. 1. Frequency Characteristics while Driving Under freely flowing conditions of traffic, when you drive a bus on a public road, the traffic noise level showed a change of 6.2 dB(Z) from 83.1 dB(Z) to 89.3 dB(Z).The change of traffic noise level was 6.3 dB(Z) from 81.7 dB(Z) to 88 dB(Z) when a van was driven, and 10.8 dB(Z) from 79.5 dB(Z) to 90.3 dB(Z) when a one-ton truck was driven. Also, the change of traffic noise level was 18.6 dB(Z) from 81.3 dB(Z) to 99.9 dB(Z) when a motorcycle was running. All vehicles except for the motorcycle showed similar noise levels of 31.5, 500, 1 k and 2 kHz. The bus showed the highest noise level at 63 Hz and 125 Hz, and a van and an 11 ton truck showed the highest levels at 125 Hz. The one-ton truck was measured at 63 Hz for the highest noise level. The motorcycle was measured at 250 Hz with the highest noise level of 96.7 dB(Z) and at 500 Hz with 95.5 dB(Z), indicating the highest noise level among specific vehicles. 2. Characteristic of Frequency upon Departure The noise level when an urban bus stops to depart was 94.6 dB(Z), which is higher than that of stoppage and driving. When a bus stops, the normal car have an influence on the noise level, and after departure, it brings out the highest noise at 250 Hz and 500 Hz, which is caused by noises from the engine and exhaust. The noise level when a normal car stops to depart was higher than that of stoppage and driving at 85.7 dB(Z). It is high at 63 Hz as it is being reduced from 250 Hz. While a normal car is stopping, higher noise is made at 31.5 Hz, which is considered to be caused by engine noise.