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The ride values of passenger cars are investigated for Korean subjects based on the vibration of the human bodies. When three subjects are excited by driving a vehicle on road, their responses of acceleration are measured at 12 points on their bodies according to Griffin's 12 axis system (3 translational axes on a seat surface, 3 rotational axes on a seat surface, 3 translational axes at the seat back and the 3 translational axes at the feet). Since one of the most important parameters for ride comfort is the level and duration of the root mean square acceleration experienced, the ride values, such as the seat effective amplitude transmissibility, the component ride value, and the overall ride value based on acceleration root mean square are evaluated for different four vehicles using frequency weighing functions and axis multiplying factors. The ride indices are also studied considering to the seat dynamic characteristics with subjects.

The ride values of seven cars(six passenger car and one RV car) are evaluated for 4 subjects based on the vibration of the bodies. And the seat qualities are investigated with the SEAT(seat effective amplitude transmissibility) value. The evaluated values are arranged as DB in html files. Since one of the most important parameters for ride comfort is the level and duration of the root mean square acceleration experienced, the acceleration responses of subjects are measured at 8 points on their bodies(3 Translational axes on the seat surface, 3 translational axes at the feet and 2 axes(x,z) at the backrest) when the subjects are excited by driving a vehicle on the road. The ride values such as the overall ride value, the component ride values and the seat effective amplitude transmissibility based on acceleration root mean square are evaluated for different seven vehicles using frequency weighting functions and axis multiplying factors.

This paper deals with the determination of the seat sponge parameters by using the estimated nine degree-of-freedom biodynamic model. The suggested nine DOF model has multiple outputs that include the major axes for evaluating the ride quality in vehicles such as z-axis of the floor, hip, and x-axis of the back, in addition to the z-axis of the head for describing the whole-body vibration. It is intended to resemble the sitting posture with backrest support. Three experiments were executed to validate the proposed models. The first one was to measure the acceleration of the floor and hip in z-axis, the back in x-axis, and the head in z-axis under exciter. From this measurement, the transmissibilities of each subject were obtained. The second one was the measurement of the joint position by the device having pointer, and contact point between human body and seat by pressure sensor. The third one was the dropping test to measure the seat and back cushion.