• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.218-223
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• 2011

Seated human subjects have been exposed to vertical vibration so as to investigate six-axis biodynamic response. Sixteen males were exposed to random vertical vibration in the frequency range(3~40Hz) at one vibration magnitude(0.224m/$s^2$ r.m.s.). Forces were measured in the vertical, fore-and-aft, lateral, roll, pitch and yaw direction on the seat. The median of cross-axis apparent mass magnitude in the fore-and-aft direction could reach up to 20% of the apparent mass magnitude at resonance frequency. And the median of apparent eccentric mass magnitude in the roll direction could reach up to 15% of the apparent eccentric mass magnitude in the pitch direction at resonance frequency. But cross-axis apparent mass in the lateral direction and apparent eccentric mass in the yaw direction showed very small.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.10
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• pp.897-904
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• 2011

When whole-body is exposed to vertical vibration, asymmetry shape of human body affects the response on the translational(fore-aft, lateral, vertical) and rotational(roll, pitch, yaw) motion. While the translational motion has been studied with various titles, it has been rare to study the rotational motion of human body exposed to vertical excitation because of lack of experimental equipment. This study was performed by using a 6-axis force plate installing strain gage type sensors for the rotational response. Sixteen male subjects were exposed to vertical vibration on rigid seat in order to investigate apparent mass of three translational motion and apparent eccentric mass of three rotational motion. Random signal was generated to make excitation vibration which was on an effective frequency range of 3~40 Hz, and magnitude of 0.224 m/$s^2$ r.m.s. The frequency range and magnitude used was selected for the vibration of passenger vehicle on idling condition. As the result, cross-axis apparent masses of fore-and-aft and lateral direction were not significant showing 20 % and 3 % of vertical apparent mass relatively. And apparent eccentric mass of pitch motion was dominant when compared to that of roll and yaw motion, which is reasoned by asymmetry direction of human body sitting on a seat.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.12
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• pp.1121-1127
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• 2010

Human characteristic responding to idle vibration on passenger vehicle was studied to find if affected by seating posture of passenger. When twelve male subjects are exposed to moderate vertical vibration of 0.224 $m/s^2$ r.m.s. at frequency range from 3 Hz to 40 Hz, it was found that seating posture significantly affects to biodynamical characteristics, apparent mass and apparent eccentric mass, at most range of idle vibration frequency(20~40 Hz). The supported thigh contact on rigid seat showed bigger values in the two biodynamical characteristics than the average thigh contact. The bigger apparent mass and apparent eccentric mass in the seating posture of the supported thigh contact can be assumed more strengthened muscle at the frequency range.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.455-460
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• 2012

Thirteen taxi drivers as the subject in the experiment were exposed to vertical vibration which is controlled on a rigid seat reflecting vibration on passenger vehicle. They were employed not only to get human response of objective measurement but also to make subjective evaluation of the vibration. The subjective evaluation was estimated using the absolute discomfort threshold of the controlled vibration, which was achieved with the three-down one-up method that is widely used in the field of psychophysics. As the result, apparent mass and apparent eccentric mass as objective human response tend to gradually decrease when frequency of the vibration increases. The absolute discomfort threshold was increased in case of increasing the frequency. Concludingly, the subjective discomfort evaluation is highly correlated with the objective human responses at the range of idle vibration on passenger vehicle.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.5
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• pp.422-428
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• 2012

Thirteen taxi drivers as the subject in the experiment were exposed to vertical vibration which is controlled on a rigid seat reflecting vibration on passenger vehicle. They were employed not only to get human response of objective measurement but also to make subjective evaluation of the vibration. The subjective evaluation was estimated using the absolute discomfort threshold of the controlled vibration, which was achieved with the three-down one-up method that is widely used in the field of psychophysics. As the result, apparent mass and apparent eccentric mass as objective human response tend to gradually decrease when frequency of the vibration increases. The absolute discomfort threshold was increased in case of increasing the frequency. Concludingly, the subjective discomfort evaluation is highly correlated with the objective human responses at the range of idle vibration on passenger vehicle.