We reported ergonomic practice for the development of a swing chair to induce drowsiness and relaxation. In the process of functional examination and improvement of the chair, we examined not only the chair angles but also the swinging amplitude to enhance the effect of using the chair. The subsequent verification process suggested that drowsiness and relaxation could be induced by adjusting the position and swinging speed of the chair according to an individual’s preference. Finally, the developed swing chair was commercialized and sold, and a survey of its customers confirmed that they were highly satisfied with the product. From these practices, the role and issues of ergonomics will be discussed in terms of developing products that have an impact on the human body and mind.

Oral cavity is an important part of human body, and oral health is the basis of overall health. Oral diseases can interact with systemic diseases. This study aimed to investigate whether there is a correlation between pulse wave indices measured by photoplethysmography （PPG） and salivary secretion by analyzing data collected from two healthy adult female subjects. The results revealed a significant negative correlation between the integral of the pulse wave index and the integral of salivary secretion within individuals. In other words, pulse wave measurements can be used to evaluate the environmental and human conditions that affect saliva secretion has been demonstrated, salivation, making it easier to design a meaningful lifestyle for oral hygiene.

We report the results of psychological evaluation of a floor wiper developed in accordance with the consumer needs for gap cleaning of floors. Specifically, we examined the effect of cleaning floors with this wiper on mood and usability in two experiments. Participants cleaned the floor of a dining-like environment, including gaps between the furniture. They used two different floor wipers under two conditions, a） an easy-wiper condition in which participants used a wiper that targeted the gaps, and b） a difficult-wiper condition in which participants used a wiper that occasionally got stuck in the gaps. Mood ratings were taken before and after. After the cleaning, the usability of wiper was also measured. The results showed that positive mood increased, and negative mood decreased under the easy-wiper condition compared to the difficult-wiper condition after the cleaning task （Experiment 1）. In Experiment 2, the positive/negative mood differences between the tool conditions were smaller in an environment with fewer obstacles. The usability was generally higher in the easy-wiper than in the difficult-wiper conditions. The present study identified that floor cleaning with a wiper, compatible with the floor-cleaning environment, improved the post-cleaning moods. These results could be derived from the processing fluency of haptic maneuvering of wipers.

This study was aimed at investigating the effects of the trunk rising angle on pressure sensation and subjective postural stability when sitting at a desk with the prone posture, such as for napping during office or school hours. Eighteen healthy young adults took a 15-min prone posture at a desk using a support base at a tilt angle of 60°, 45°, or 30° to adjust the trunk rising angle （angle between the trunk and the horizontal plane） or without a base （control condition）. Satisfaction was significantly higher under all support base conditions than under the control condition. In addition, the 60° condition showed the largest trunk rising angle and significantly lesser pressure sensation and higher subjective postural stability compared to the control condition. These results suggest that, when napping with the prone posture at a desk, a moderate trunk rising angle is recommended based on body pressure and postural stability, and a pillow or other nap accessory that enables this posture may be used.