Ergonomic Study of Mattress Firmness by Measuring Spinal Curve and Sleep Quality

Tetsuo Katsuura,Masaki Teshima,Yali Xia,Soomin Lee,Yoshika Takahashi,Ikuo Asai,Yoshihiro Shimomura 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5

We examined the influence of mattress firmness on the spinal curve, sleep quality, and subjective evaluations in healthy subjects. The firmness of the three equal parts of air /mattress was controlled by the air pressure in each part. In Experiment 1, we created nine air mattress conditions by setting the air pressure of each of the upper and middle parts at 4, 6, or 8 kPa, and that of the lower part at 6 kPa. We measured the spinal curves of 10 healthy young male subjects from the coccyx to the 7th cervical vertebra by a fiber optic-based 3D bend and twist sensor, while they laid down on their right side with the angle of the trunk and thigh at 135° (abbreviated as lying135°) and when they laid supine, in each of the nine mattress conditions. We found that the spinal curve during supine position with the conditions of lower part: 6 kPa, middle: 4 kPa, and upper: 6 kPa (“6:4:6”) was the most similar to that during lying135°, which makes the spinal curve natural. However, the subjective evaluation of "comfort of the mattress" by a visual analog scale (VAS) scored highest in the 6:4:8 condition. As Experiment 2, we compared sleep quality achieved with the 6:4:6 and 6:4:8 conditions over each of seven consecutive nights (three adaptation nights and four for analysis) in subjects’ homes. The sleep quality achieved by 20 healthy adult males and females was assessed by means of actigraphy, the standardized Oguri-Shirakawa-Azumi (OSA) Sleep Inventory (middle-aged version), and VAS subjective evaluations. The estimated sleep quality measured on the 6:4:6 mattresses was significantly higher than that on the 6:4:8 mattress. The VAS evaluations of "comfort of the lower back" and "comfort of the upper back" were also higher for the 6:4:6 mattress. There were no significant differences in the OSA scores between mattress conditions. Our results indicate that the 6:4:6 mattress condition, which appeared to provide a natural spinal curve, provided higher sleep quality and higher subjective evaluations during actual use compared to the 6:4:8 condition.

Ergonomic Study of Mattress Firmness by Measuring Spinal Curve and Sleep Quality

( Tetsuo Katsuura ),( Masaki Teshima ),( Yali Xia ),( Soomin Lee ),( Yoshika Takahashi ),( Ikuo Asai ),( Yoshihiro Shimomura ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

We examined the influence of mattress firmness on the spinal curve, sleep quality, and subjective evaluations in healthy subjects. The firmness of the three equal parts of air /mattress was controlled by the air pressure in each part. In Experiment 1, we created nine air mattress conditions by setting the air pressure of each of the upper and middle parts at 4, 6, or 8 kPa, and that of the lower part at 6 kPa. We measured the spinal curves of 10 healthy young male subjects from the coccyx to the 7th cervical vertebra by a fiber optic-based 3D bend and twist sensor, while they laid down on their right side with the angle of the trunk and thigh at 135º (abbreviated as lying135º) and when they laid supine, in each of the nine mattress conditions. We found that the spinal curve during supine position with the conditions of lower part: 6 kPa, middle: 4 kPa, and upper: 6 kPa (6:4:6) was the most similar to that during lying135º, which makes the spinal curve natural. However, the subjective evaluation of comfort of the mattress by a visual analog scale (VAS) scored highest in the 6:4:8 condition.

Effects of a Vertical and Horizontal Console Position on Operator Muscular Stress During Ultrasonic Diagnosis

( Hiroyuki Suzuki ),( Takayoshi Saito ),( Tetsuo Katsuura ),( Yoshihiro Shimomura ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

A diagnostic ultrasound system is an apparatus to aid in examination and diagnosis by displaying cross-sectional images of body tissues, their movements, and blood flow produced based on the intensities and phases of reflected echoes. Most the operators operate the probe by the right hand and the operation panel by the left hand during ultrasonic diagnosis in Japan. Ultrasound examinations tend to put sonographers in unnatural postures, which may lead to musculoskeletal disorders. In this study, we focused on the height and the horizontal positioning of the operation panel of the diagnostic ultrasound system to quantitatively assess the influence of panel height (work plane height) and work plane position on musculoskeletal stress during scanning in a sitting position. Eight subjects (6 males and 2 females) were asked to perform a simulated scanning task that involved touching 9 points on the operation panel at 4 different panel heights. Five subjects (2 males and 3 females) were asked to perform a simulated scanning task that involved touching fie points on the control panel, with the work plane set at different positions in space. Electromyograms of each part of the body and wrist joint angles indicated that the optimum height of the operation panel during scanning in a sitting position was elbow height, the least stressful position of the left hand was about 350 mm from the center of the trunk in the longitudinal (front-back) direction and 100 mm left of the center of the trunk in the lateral (right-left) direction.

Effects of a vertical and horizontal console position on operator muscular stress during ultrasonic diagnosis

Hiroyuki Suzuki,Takayoshi Saito,Tetsuo Katsuura,Yoshihiro Shimomura 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5

A diagnostic ultrasound system is an apparatus to aid in examination and diagnosis by displaying cross sectional images of body tissues, their movements, and blood flow produced based on the intensities and phases of reflected echoes. Most the operators operate the probe by the right hand and the operation panel by the left hand during ultra -sonic diagnosis in Japan.Ultrasound examinations tend to put sonographers in unnatural postures, which may lead to musculoskeletal disorders. In this study, we focused on the height and the horizontal positioning of the operation panel of the diagnostic ultra -sound system to quantitatively assess the influence of panel height (work plane height) and work plane position on musculoskeletal stress during scanning in a sitting position. Eight subjects (6 males and 2 females) were asked to perform a simulated scanning task that involved touching 9 points on the operation panel at 4 different panel heights. Five subjects (2 males and 3 females) were asked to perform a simulated scanning task that involved touching five points on the control panel, with the work plane set at different positions in space. Electromyograms of each part of the body and wrist joint angles indicated that the optimum height of the operation panel during scanning in a sitting position was elbow height, the least stressful position of the left hand was about 350 mm from the center of the trunk in the longitudinal (front–back) direction and 100 mm left of the center of the trunk in the lateral (right–left) direction. The height of the operation panel during scanning in a sitting position affects the stress on the forearm and shoulder. We indicated that the optimum height of the operation panel was elbow height. The longitudinal position of the control panel during scanning in a sitting position affected the stress in the left forearm and left lumbar regions. The lateral position of the control panel during scanning in a sitting position affected the stress in the left shoulder rgion.We indicated that the least stressful position of the left hand was these on the horizontal positioning of the operation panel.

生体情報によるエアコンの自動制御について

? 元慶(Shan Yuanqing),岩永光一(Iwanaga Koichi),原田一(Harada Hajime),勝浦哲夫(Katsuura Tetsuo) 한국디자인학회 1997 디자인학연구 Vol.- No.22

The Influence of Laterality during Gait Cycle on Manual Pushing

Kadek Heri Sanjaya,Yoshika Takahashi,Soomin Lee,Yoshihiro Shimomura,Tetsuo Katsuura 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5

The objective of this study was to investigate the influence of laterality in various speeds of gait cycle on manual pushing which has been given less attention. The participants of this study were 17 healthy males, 6 of them were left-handers. They performed trials by pushing a wall force plate during walking on a treadmill in three speeds: 1.5, 3, and 4 km/h. The participants were instructed to push at no less than 50% of their maximum static pushing force. Electromyogram (EMG) data was collected bilaterally from tibialis anterior, soleus, lumbar erector spinae and triceps brachii muscles. Time series analysis was normalized into gait cycle which was described as time between heel strike and just before the next heel strike of the same foot and it consisted of 100 data points. To show symmetry, cross-correlation function analysis from the left and right gait cycle variables were compared. Asymmetrical gait cycle period was only observed among right-handers at 3 km/h speed where right gait cycle had longer time than left gait cycle. Pushing force symmetry index was not changed in all of the three speeds in both right-handers and left-handers. Pushing force exertion showed asymmetry in between left and right gait cycle in 4 km/h pushing. The activation pattern of tibialis anterior, soleus and lumbar erector spinae muscles did not show any significant change due to different speeds of manual pushing. However, triceps brachii showed differences due to speeds among left-handers. The better understanding of laterality on manual pushing will help in not only better design of manual pushing tools and tasks but also on its application beyond manual materials handling.

The Influence of Laterality during Gait Cycle on Manual Pushing

( Kadek Heri Sanjaya ),( Yoshika Takahashi ),( Soomin Lee ),( Yoshihiro Shimomura ),( Tetsuo Katsuura ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

The objective of this study was to investigate the influence of laterality in various speeds of gait cycle on manual pushing which has been given less attention. The participants of this study were 17 healthy males, 6 of them were left-handers. They performed trials by pushing a wall force plate during walking on a treadmill in three speeds: 1.5, 3, and 4 km/h. The participants were instructed to push at no less than 50% of their maximum static pushing force. Electromyogram (EMG) data was collected bilaterally from tibialis anterior, soleus, lumbar erector spinae and triceps brachii muscles. Time series analysis was normalized into gait cycle which was described as time between heel strike and just before the next heel strike of the same foot and it consisted of 100 data points. To show symmetry, cross-correlation function analysis from the left and right gait cycle variables were compared. Asymmetrical gait cycle period was only observed among right-handers at 3 km/h speed where right gait cycle had longer time than left gait cycle. Pushing force symmetry index was not changed in all of the three speeds in both right-handers and left-handers. Pushing force exertion showed asymmetry in between left and right gait cycle in 4 km/h pushing. The activation pattern of tibialis anterior, soleus and lumbar erector spinae muscles did not show any significant change due to different speeds of manual pushing.

ヒト肩用動作測定器の開発

下村義弘(Shimomura Yoshihiro),岩永光一(Iwanaga Koichi),原田一(Harada Hajime),勝浦哲夫(Katsuura Tetsuo) 한국디자인학회 1997 디자인학연구 Vol.- No.22