C. Stephanidis (Ed.): HCII 2014 Posters, Part II, CCIS 435, pp. 473–478, 2014. © Springer International Publishing Switzerland 2014 Relationship between Comfortable Feelings and Distribution of Seat Pressure in Sustaining a Sitting Posture for a Long Time Yasuyuki Matsushita, Noriaki Kuwahara, and Kazunari Morimoto Graduate School of Science and Technology Kyoto Institute of Technology Matsugasaki, Sakyo, Kyoto 606-85858, Japan {yasuoyasuoyasu,noriaki.kuwahara,morix119}@gmail.com Abstract. It is necessary to clarify the method for measuring a comprehensive evaluation from plurality criteria of the physical load when they sitting on a chair, because they cannot access their sitting posture during a continuous working. Further, in order to provide a chair that fits the user, it is important to find simple evaluation method of comfort when sitting on a chair. Further, in order to develop a good chair that fits to the users, it is important to find simple evaluation method on comfortable sitting conditions when sitting on a chair. The aim of this paper is to show some rating factors on comfort or discomfort when sitting on a chair for a long time. The experiment was carried out using an office chair. Body pressure distribution of the buttocks was measured by electrical seat sensor for an hour of one session. In addition, they were inter- viewed on five items of subjective evaluation every five minutes during an hour sitting situation. According to the experiments, we found that elapsed time and two feature values of the total load area of the body pressure distribution and the ratio of the particularly highly pressure area are effective to predict discom- fort. And we derived a regression equation to predict the increase of discomfort using the average pressure distribution when they are sitting. Keywords: chair, comfort, pressure, posture. 1 Introduction Workers, some occupations of clerical staff and programmers etc., spend a lot of time to sit on office chair during all day long. They do not become something of the physi- cal problem directly in compared to the senior persons because they can change the sitting posture by themselves and do not obstruct their bloodstream for maintain their posture. However, they get tired of keeping the same posture for a long time during all day, and it generates huge fatigue and pain to them. These situations will derive a low motivation and low efficiency of their works. We have to clarify the reason of their fatigue, pain and relations of decrease of the comfort, to occur by continuing sitting down of the chair for a long time because we