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Riding comfort on the seat is one of the important factors for vehicle comfort. To analyze riding comfort, there were some models for predicting human vibrations in the past studies. On the other hand, it is strongly affected by human body motion caused by vehicle excitation during driving especially low frequency, but it is difficult to predict human motion due to an unclear mechanism of muscle reflex. The purpose of this study is to construct virtual riding comfort testing simulation based on virtual prototyping of the seat. In this study, a virtual occupant model that predicts occupant motion on the seat against external excitation including muscle reflex for maintaining sitting posture constructed. The whole body was modeled as 15 segments biomechanical model (1D) with wobbling mass. Each joint has passive elastic torque and damping torque springs. Human body surface was modeled as rigid shape.

An anatomically detailed elderly human body model is under development. Using the anthropometric database of domestic nation-wide size survey, SizeKorea, a standard size and shape of 50th %tile elderly was constructed. Through the local recruitment process, a male volunteer with 71 years of age, 163cm of height and 63kg of weight has been selected. The exterior (skin) geometries were acquired from whole body 3D laser scan. And the geometries of interior (skeleton and organ) were reconstructed using CT scanning in a supine posture, and then adjusted in an occupant posture based on X-ray, and Ultrasonic data. A particular attention has been paid into the combining process of exterior and interior geometries especially for joint articulation positions since they were measured at different postures (sitting vs. supine).

Discomfort models play a significant role in ergonomic simulation. More detailed and specific discomfort models are required for older drivers who represent the fastest-growing segment of the driving population. Owing to the physical degradation, various biomechanical discomfort factors should be incorporated into the model to properly evaluate discomfort for the older population group. In this experimental study we attempted to identify and quantify biomechanical factors that affect the older drivers' discomfort ratings. Different egress motion strategies (e.g., with and without using assist devices) were designed to induce various physical activities. The corresponding discomfort ratings were then produced. From the kinematic analysis using a digital human body model with reconstructed egress motion, the hip abduction was found to have the most statistically significant effect on the discomfort rating.

Both experimental and numerical simulations were attempted to investigate postural changes of sitting occupants such as seat back pressure distribution and lordotic curvatures of lumbar spine with the different configurations of lumbar support. Using the detailed anatomical digital human body models, a fairly good quantitative prediction on the increase and transfer of peak pressure to lumbar region and the lordotic curvature raise of the lumbar spine as the support prominences was obtained.

New human body models have been developed with recent anthropometry for riding comfort simulation. External geometry of the models was acquired from the three dimensional whole body laser scanning of recruited volunteers in a driving position. The selection criteria for volunteers with standard size and shape were derived from a statistical factor analysis of the SizeUSA database. As a practical application of the model in a design process, comfortable driving postures were constructed by using the Cascade Prediction Model (CPM) which takes into account both interior package layout and the driver's anthropometry.

In order to improve the biofidelity of a finite element human body model, previously introduced as PAM-Comfort model, the modeling of lumbar spine, buttock and trunk back flesh and abdominal part have been updated. The modeling of the lumbar spine has been improved for its mechanical characteristics of articulation. The modeling of abdominal part has been switched with solid mesh from the air-bag with membrane elements to enhance the mass distribution feature of the model. The mesh quality of buttock and trunk back flesh became finer for a more accurate prediction of seating pressure distribution. The new features of the model were verified by the experimental data with human subjects.

In order to assess the seating comfort design of a vehicle seat system, a full finite element occupant model, with anatomically precise features and deformable tissues, has been developed. This paper describes the experiments which were performed in order to assess the biofidelic accuracy of this model. First, static pressure distribution measurements, with human volunteers, have been performed. People of different morphological types were asked to sit on a PU foam cushion with various postures, which were captured by photographs and X-Ray measurements. Pressure sensors were used to determine the corresponding pressure distribution patterns. Then, the FE occupant model was used to simulate the same experiments, and the numerical results were compared to the experimental ones.

Crash injuries in lower extremities are usually not fatal but may result in long-term impairment and immobility. Current understanding of these injuries is still quite limited from the biomechanical point of view. It is known that they occur often during frontal offset collisions in which intrusion of the toe pan and instrument panel frequently occur but are not always associated with their causation. Assessment of these injuries using the Hybrid III dummy is limited because of its limited biofidelic structure and inaccurate injury criteria. Accordingly, THOR-LX, the retrofit of the lower leg of the Hybrid III, has been introduced with an improved design for ankle motion and capacity of injury prediction. In this study, the different ankle joint characteristics and outcomes of both the Hybrid III and the THOR/LX have been quantitatively analyzed for an NCAP 40% offset crash with a small size sedan.

Whiplash injuries due to automotive collisions have occupied a major portion of the insurance claims in Korea and other nations. In this study, a survey of head restraint use in the field was performed by measuring the positions of head restraints in 1,100 passenger vehicles in the downtown and outskirts areas of Seoul. Using an international protocol published by the Research Council for Automobile Repairs (RCAR), 19% of the measured head restraint positions were evaluated as “good” and 36% were evaluated as “poor”. This result differentiates a recent report of the improvement in design of head restraints geometry and reveals that motorists are not appropriately utilizing head restraints. Statistical analysis of the survey results revealed valid correlations between the measurements and subjective questions. Simulations with various parameters such as impact speed, direction and head restraint positions were also performed utilizing an FE human model.