This study explodes the relationships between the height adjustment of bed sectors and subjective comfort depending on three types of sleeping positions. An adjustable bed system that regulates the heights of 8 adjustment sectors of the bed was developed. To evaluate the comfort of 9 body areas, subjective ratings were requested from 64 subjects ranging in age from 25 to 50. The subjects included 29 males and 35 females. For an objective evaluation, the patterns of pressure distribution were investigated according to the three sleeping positions. During two separate states (before bed adjustment and after bed adjustment), measurements of the adjusted bed height and pressure distribution, and subjective ratings according to three sleeping positions were performed. Based on the results of the adjusted heights of the 8 sectors in the bed, the subjects preferred the W-shaped sleeping posture in both the supine and side positions. However, the U-shaped sleeping posture was preferred in the prone position. With respect to these sleeping positions, the heights of sectors significantly correlated with the subjective ratings presented by the subjects, as well as the ratios of pressure. C 2009 Wiley Periodicals, Inc.
This study collected the data concerning preferred driving postures and adopted seat adjustment levels. Then, the relationships among drivers' body sizes, postural angles, positions and angles of the seat, and body pressure distribution were investigated. An experiment was conducted to find observed optimum driving posture, seat adjustment level, and body pressure. Thirty-six subjects (20 males, 16 females) were selected to be representative of the automotive driving population of Korea. The preferred ranges for optimum postural comfort of Korean were presented. Considering the relationships among body sizes, driving postures, and seat adjustment levels, there was trade-off on the comfortable driving posture between steering wheel handling and pedal operation. Estimation models on observed optimum driving posture and seat adjustment level were constructed. The developed models enable us to estimate the quantitative optimum driving posture and seat adjustment level with a certain driver's physical dimensions.
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