Exploring the appropriate test methods to examine the efects of frefghter personal protective equipment on mobility

손수영,Satoshi Muraki,Yutaka Tochihara 한국의류학회 2022 Fashion and Textiles Vol.9 No.1

This study aimed to ascertain the appropriate test methods for the investigation of the efect of personal protective equipment on mobility of frefghters. Nine male volunteers performed a physical performance test (crawl, obstacle course, side-to-side jumps, heavy-object drag, and step-ups), functional balance test (functional reach, timed up and go, and wooden plank time), range of motion test, and subjective evaluation under four clothing conditions with diferent weights and combinations of personal protective equipment. The results showed that physical performance, functional balance ability, and joint angles signifcantly declined with increased weight of personal protective equipment. On subjective evaluation, wearing heavy personal protective equipment increased perceived exertion and discomfort on movement. Our results proved that some of our test methods, including the obstacle course, side-toside jumps, functional reach, timed up and go, range of motion test, and subjective evaluation, can be used to examine the mobility of personal protective equipment wearers. The fndings of this study provide an efective guide for researchers and frefghters regarding the evaluation of mobility with personal protective equipment, as well as for manufacturers in the development of enhanced, comfortable personal protective equipment.

보조적인 힘이 근장력 변동성의 크기와 불규칙성에 미치는 영향

최지원,Satoshi Muraki,Ping Yeap Loh 대한인간공학회 2024 大韓人間工學會誌 Vol.43 No.4

Objective: This study aims to observe how force output patterns alter when assistive force is provided during mechanically assisted force coordination with isometric elbow flexion. Background: Force coordination between humans and assistive robots requires human muscle force to be released in response to mechanical assistance. However, little is known about how motor performance of muscle force release with assistive force is different from the one without assistance. This study investigated how force variability parameters of coefficient of variation (CV) of force output, sample entropy, and stabilization time alter during isometric force control with assistive force. Method: Eleven male participants (mean: 24.4; SD: 1.5) participated in this experiment. Electromyography electrodes were placed on the surfaces of biceps and triceps muscles. The participant maintained an isometric elbow flexion force of 47N with the dominant arm along a linear trajectory shown on a screen. Under the conditions of assistive force provision, the assistive force was gradually provided as 25% or 50% of the isometric force for 0.5s by operating the actuator so that the participant could release their muscle force. Under the conditions where assistive force was not provided, the participant released their isometric force by 25% or 50% along with the visual guidance on the screen. From the manual force output, release stabilization time of force control was calculated and the CV and sample entropy were computed to represent size of force variability and time-series data irregularity, respectively. Results: Regardless of whether assistance was provided, the activation of biceps and triceps brachii muscles decreased after force release. This study found that compared to the visually guided conditions, mechanically assisted conditions showed a lower CV, longer stabilization time, and higher sample entropy. When the muscle force was greatly released (50% release of the isometric force), a longer stabilization time and greater CV were observed, but the entropy was lower compared to the slight muscle force release (25% release). Conclusion: This study suggests that when the magnitude of force release is relatively large, the size of force variability increases, while the irregularity decreases. This could imply that humans probably have potential adaptability for greater assistive force provided during mechanically assisted force coordination. Application: The results of the current study can be used to determine the amount of assistive force provided during human-robot collaboration.

The Effects of Touch Button Size to the Operability of Touchscreen

( Jinghong Xiong ),( Satoshi Muraki ),( Kiyotaka Fukumoto ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

The present study investigated the influence of button size on the operability of a touch panel screen and compared this influence between young adults and the elderly. Twenty-one young adults (age: 22.3±1.5 years) and twenty elderly people (age: 68.1±4.9 years) operated the interface of a touch panel screen with their right index finger. It displayed 0-9 numeric square buttons at 6 different size conditions (6, 8, 10, 12, 14 and 16 mm). Smaller buttons at and below 10 mm increased the operation time and error rate, and decreased the subjective overall operability. The influence of button size was greater in the elderly than in the young adults. The reaction positions were located to the right of the center of the button, which made the reaction position approach the right outline of the button, especially for smaller buttons. These results suggest that smaller buttons should be avoided in interfaces on touch panel screens, especially those used by the elderly.

The Effects of Touch Button Size to the Operability of Touchscreen

Jinghong Xiong,Satoshi Muraki,Kiyotaka Fukumoto 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5

The present study investigated the influence of button size on the operability of a touch panel screen and compared this influence between young adults and the elderly. Twenty-one young adults (age: 22.3±1.5 years) and twenty elderly people (age: 68.1±4.9 years) operated the interface of a touch panel screen with their right index finger. It displayed 0-9 numeric square buttons at 6 different size conditions (6, 8, 10, 12, 14 and 16 mm). Smaller buttons at and below 10 mm increased the operation time and error rate, and decreased the subjective overall operability. The influence of button size was greater in the elderly than in the young adults. The reaction positions were located to the right of the center of the button, which made the reaction position approach the right outline of the button, especially for smaller buttons. These results suggest that smaller buttons should be avoided in interfaces on touch panel screens, especially those used by the elderly.

The observation of children`s holding position to redesign elementary school chair for easy carrying and moving

Lu’lu’ Purwaningrum,Satoshi Muraki 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5

Objectives. Carrying and moving chairs enable and improve learning activities at school, which leads to better quality of education. At elementary schools in Indonesia and other developing countries, only one size of chair has been used for all ages and grades, therefore, making it heavy for younger children. The objective of the present study was to observe the motion of carrying and moving an elementary school chair by children. Methods. A total of 41 children consisting of 16 Indonesian and 25 Japanese children (17 boys and 24 girls) aged 6, 7, 8 and 9 participated in this study. We used three elementary school chairs (1 Indonesian and 2 Japanese chairs). The participants carried and moved the chairs 3 m with an ordinary speed, and were allowed to hold any part of the chair that was convenient for them. We recorded their motion when carrying and moving the chair. Results. The chair was carried at the side or in front of the child’s body, and the chair being in a lateral position is the most popular method of carrying and moving (75%). In all methods, participants showed a preference in using two particular chair parts to hold the chair. Conclusions. Careful consideration is needed on the design of elementary school chairs from the perspective of the main methods and holding pattern for carrying and moving them, especially heavy chairs that are used in elementary schools in Indonesia.

Deformation of Median Nerve during Active and Passive Wrist Holding at Proximal Carpal Tunnel

( Ping Yeap Loh ),( Satoshi Muraki ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

The first objective of this study was to identify the deformation of the median nerve cross-sectional area (MNCSA) at different wrist active and passive holding positions. The second objective was to compare the wrist circumference, wrist width, and wrist depth between dominant and non-dominant hands. A total of eight right-handed healthy male adults (age 27.0 ±3.5 years) participated in this study. Ultrasound examination was performed at the proximal carpal tunnel to examine the median nerve on the transverse plane. A total of three wrist positions were examined, namely, wrist neutral, wrist flexion 30°, and wrist extension 30°, in active and passive holding positions for both dominant and non-dominant hands. Paired t-test showed significant differences between dominant (D) and non-dominant (ND) hands in wrist circumference, wrist width, and wrist depth (D = 39.6 ± 2.8 mm, ND = 38.3 ± 2.7 mm, p<0.01). The differences of MNCSA between dominant and non-dominant hands were significant (p<0.001) at both active (D = 7.93 ± 0.63 mm2, ND = 6.98 ± 0.42 mm2) and passive holding positions (D = 8.22 ± 0.72 mm2, ND = 7.06 ± 0.44 mm2). Two-way repeated-measures ANOVA showed that wrist flexion 30° and wrist extension 30°caused significant reductions in MNCSA when compared with wrist neutral (p<0.001) in both active and passive holding positions.

Deformation of Median Nerve during Active and Passive Wrist Holding at Proximal Carpal Tunnel

Ping Yeap LOH,Satoshi MURAKI 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5

The first objective of this study was to identify the deformation of the median nerve cross-sectional area (MNCSA) at different wrist active and passive holding positions. The second objective was to compare the wrist circumference, wrist width, and wrist depth between dominant and non-dominant hands. A total of eight right-handed healthy male adults (age 27.0 ± 3.5 years) participated in this study. Ultrasound examination was performed at the proximal carpal tunnel to examine the median nerve on the transverse plane. A total of three wrist positions were examined, namely, wrist neutral, wrist flexion 30°, and wrist extension 30°, in active and passive holding positions for both dominant and non-dominant hands. Paired t-test showed significant differences between dominant (D) and non-dominant (ND) hands in wrist circumference (D = 15.9 ± 0.6 cm, ND = 15.7 ± 0.6 cm, p<0.05), wrist width (D = 56.3 ± 3.6 mm, ND = 54.0 ± 2.1 mm, p<0.05), and wrist depth (D = 39.6 ± 2.8 mm, ND = 38.3 ± 2.7 mm, p<0.01). The differences of MNCSA between dominant and non-dominant hands were significant (p<0.001) at both active (D = 7.93 ± 0.63 mm<SUP>2</SUP>, ND = 6.98 ± 0.42 mm<SUP>2</SUP>) and passive holding positions (D = 8.22 ± 0.72 mm<SUP>2</SUP>, ND = 7.06 ± 0.44 mm<SUP>2</SUP>). Two-way repeated-measures ANOVA showed that wrist flexion 30° and wrist extension 30° caused significant reductions in MNCSA when compared with wrist neutral (p<0.001) in both active and passive holding positions. However, wrist active and passive holding did not have a significant effect on MNCSA changes. In conclusion, our findings showed that significant reduction of MNCSA was associated with wrist flexion-extension motion and there was significant bilateral asymmetry in physical characteristics of the wrist.

The Observation of Children`s Holding Position to Redesign Elementary School Chair for Easy Carrying and Moving

( Lu`lu` Purwaningrum ),( Satoshi Muraki ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

Objectives. Carrying and moving chairs enable and improve learning activities at school, which leads to better quality of education. At elementary schools in Indonesia and other developing countries, only one size of chair has been used for all ages and grades, therefore, making it heavy for younger children. The objective of the present study was to observe the motion of carrying and moving an elementary school chair by children. Methods. A total of 41 children consisting of 16 Indonesian and 25 Japanese children (17 boys and 24 girls) aged 6, 7, 8 and 9 participated in this study. We used three elementary school chairs (1 Indonesian and 2 Japanese chairs). The participants carried and moved the chairs 3 m with an ordinary speed, and were allowed to hold any part of the chair that was convenient for them. We recorded their motion when carrying and moving the chair. Results. The chair was carried at the side or in front of the child`s body, and the chair being in a lateral position is the most popular method of carrying and moving (75%).

Age-Related Changes in Walking Motion of Japanese Females

Irma Nur AFIAH,Hiroki NAKASHIMA,Satoshi MURAKI 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5

The purpose of this study was to investigate the effects of aging on gait parameters at two different speed conditions in Japanese females. This study involved 42 healthy Japanese females who were divided into three groups: (1) 14 younger females, mean age 22.3 ± 1.6 years, (2) 14 older females (65 to 75 years old), mean age 70.7 ± 1.8 years, and (3) 14 very old females (≥ 76 years old), mean age 78.2 ± 3.5 years. Various parameters were measured: basic gait parameters (speed of walking, right step length, left step length, step length, difference between right and left step lengths, ratio of step length to height, ratio of step length to lower-limb length, and cadence) and gait cycle parameters (time of swing phase, time of stance phase, time of one gait cycle, percentage of swing phase, and percentage of stance phase). The walking speeds in groups 1, 2, and 3 were 72 ± 5.4, 71.4 ± 7.3, and 69.7 ± 6.7 at the self-selected speed, and 91.3 ± 7.4, 86.2 ± 8.3, and 85.1 ± 9.1 m/min at the fast speed, respectively. In two-way repeated-measure ANOVA, all the parameters showed statistically significant effects of speed conditions (p<0.05), except the difference between right and left step lengths. Statistically significant effects of groups were found in right step length, left step length, step length, and difference between right and left step lengths (p<0.05). In addition, significant interactions between speed conditions and groups were found in the time of swing phase, time of stance phase, and time of one gait cycle (p<0.05). Under the self-selected speed condition among the three groups, posthoc pairwise Bonferroni-corrected comparison showed significant differences in right step length, left step length, step length, and difference between right and left step lengths (p<0.05). Under the fast speed condition, however, significant differences were only found in right step length, left step length, and step length (p<0.05).

Age-Related Changes in Walking Motion of Japanese Females: Basic Analysis of Gait Motion

( Irma Nur Afiah ),( Hiroki Nakashima ),( Satoshi Muraki ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

The purpose of this study was to investigate the effects of aging on gait parameters at two different speed conditions in Japanese females. This study involved 42 healthy Japanese females who were divided into three groups: (1) 14 younger females, mean age 22.3 ± 1.6 years, (2) 14 older females (65 to 75 years old), mean age 70.7 ± 1.8 years, and (3) 14 very old females (≥ 76 years old), mean age 78.2 ± 3.5 years. Various parameters were measured: basic gait parameters (speed of walking, right step length, left step length, step length, difference between right and left step lengths, ratio of step length to height, ratio of step length to lower-limb length, and cadence) and gait cycle parameters (time of swing phase, time of stance phase, time of one gait cycle, percentage of swing phase, and percentage of stance phase). The walking speeds in groups 1, 2, and 3 were 72 ± 5.4, 71.4 ± 7.3, and 69.7 ± 6.7 at the self-selected speed, and 91.3 ± 7.4, 86.2 ± 8.3, and 85.1 ± 9.1 m/min at the fast speed, respectively.