• Title/Summary/Keyword: 주파수 가중치 곡선

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Determination of the Frequency Weighting Curves for the Estimation of Discomfort by the Steering Wheel Vibration (조향휠 진동의 안락성 평가를 위한 주파수 가중치 곡선 결정)

  • 홍석인;장한기;김승한
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.1048-1052
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    • 2003
  • This study aims to derive frequency weighting curves for the estimation of driver's discomfort by steering wheel vibration in the vertical and rotational direction with respect to a steering column. Subjective tests for the determination of equal sensation curves, inverse of frequency weighting curves, for the two kinds of vibrations were performed using the sinusoidal signals with reference amplitudes from 0.2m/s$^2$ to 0.4 m/s$^2$ in the frequency range from 5㎐ to 100㎐. Twelve subjects joined at the tests, and median values of the twelve judgments were used to determine the frequency weighting curves. Second experiment was followed to determine relative magnitude between the two frequency weighting curves by direct comparison of discomfort due to the two kinds of vibrations at 50㎐, which showed discomfort by the rotational vibration was 1.5 times of that by the vertical vibration.

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Determination of Frequency Weighting Curves for the Evaluation of Steering Wheel Vibration (체감 진동량 평가를 위한 조향 휠 진동의 주파수 가중치 결정)

  • 홍석인;장한기;김승한
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.4
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    • pp.165-172
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    • 2003
  • This study aims to find frequency weighting curves for the evaluation of drivers' discomfort by vertical and rotational steering wheel vibration. Equal sensation curves, inverse of frequency weighting curves, were determined for the two kinds of vibrations respectively by using the sinusoidal signals with reference amplitudes from 0.2 to 0.4 m/s2 in the frequency range from 5 to 100 ㎐. Twelve subjects joined at the tests, and median values of the twelve judgments were used to determine the equal sensation curves. An experiment was followed to compare the relative sensation magnitude between the two kinds of equal sensation curves, which showed discomfort by the rotational vibration was 1.5 times of that by the vertical vibration at 50 ㎐.

Measurement of the hand-transmitted vibration using a miniature 3-axes accelerometer (초소형 3축 가속도계를 이용한 수전달 진동 측정에 관한 연구)

  • 송치문;장한기;김승한;채장범
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.1043-1047
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    • 2003
  • Most of the measurement and the evaluation of hand-transmitted vibration have been performed by using a small size single axis accelerometer between the handle and the hand palm or a three axis accelerometer attached on an adapter outside the hand(indirect measurement). It is most desirable for the correct evaluation of hand-transmitted vibration form the power tool handle to measure the acceleration between the handle surface and the hand palm in the three axis(direct measurement) as recommended in ISO 5349-1. In the study three axes acceleration measurement device was developed of which the thickness was less than 7mm so that it can be placed between the handle and the palm without any inconvenience during the measurement. To verify the performance of the developed device, measured acceleration by the two methods, direct and indirect, were compared in the study.

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Evaluation of phase velocity in model rock mass using wavelet transform of surface wave (표면파에 대한 웨이블렛 변환을 이용한 모형 암반의 위상속도 예측)

  • Lee, Jong-Sub;Ohm, Hyon-Sohk;Kim, Dong-Hyun;Lee, In-Mo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.10 no.1
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    • pp.69-79
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    • 2008
  • Prediction of ground condition ahead of tunnel face might be the most important factor to prevent collapse during tunnel excavation. In this study, a non-destructive method to evaluate the phase velocity in model rock mass using wavelet transform of surface wave was proposed aiming at ground condition assessment ahead of tunnel face. Model tests using gypsum as a rocklike material composed of two layers were performed. A Piezoelectric actuator with frequencies ranging from 150 Hz to 5 kHz was selected as a harmonic source. The acceleration history was measured with two accelerometers. Wavelet transform analysis was used to obtain the dispersion curves from the measured data. The experimental results showed that the near-field effects can be neglected if the distance between two receivers is chosen to be three times the wavelength. A simple inversion method using weighted factor based on the normal distribution was proposed. The inversion results showed that the predicted phase velocity agreed reasonably well with the measured one when the wavelength influence factor was 0.2. The depth of propagation of surface wave was from 0.42 to 0.63 times the wavelength. The range of wavelength varying with phase velocity in dispersion curve matched well with that estimated by inversion technique.

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