수지진동에서의 진동강도, 손잡이온도, 소음 및 미는 힘의 복합효과에 따른 악력 및 지단피부온의 변화

Koh, Kyung-Sim,Griefahn, B.,Fritz, M.,Brode, P. 대한예방의학회 1994 Journal of Preventive Medicine and Public Health Vol.27 No.4

Recent studies reveal that grip forces during the hand-arm vibration are most significant for the genesis of vibration-induced white linger syndrome. Therefore, exerted grip forces and skin temperatures of fingers were regarded as dependent variables in experiments and the effects of grip temperature, noise, pushing force, vibration and the combined effect of vibration and pushing force were studied. The objectives of the present study were, first, to varify and compare the changes of grip force affected by grip temperature, noise, pushing force, vibration and the combined effect of vibration and pushing force and, second, to observe the reaction of finger skin temperature affected by above factors. Forty-six healthy male students ($25.07{\pm}2.85$) participated in five systematically permuted trials, which endured 4 minutes each other. Experiments were executed in a special chamber with an air temperature of 21C. In each experiments, the subjects were exposed to five experiment types: (1) grip force of 25N only, (2) pushing force of 50N, (3) acceleration of vibration $7.1m/sec^2(z-direction)$, (4) pink noise of 95 dB (A) and (5) combination of pushing force 50N and acceleration of vibration $7.1m/sec^2$. A repeated-measures analysis of variance (ANOVA) was performed on the grip force to test whether it was affected by noise, pushing force, vibration and pushing force. The present results show that vibration was significantly related to the increase of grip force, but the other factors, such as pushing force, noise and grip temperature had no signigicant influence on the increase of grip force, and that the reaction of finger skin temperature were significantly affected by the skin temperature at start of experiment and grip temperature, not grip force and other experimental conditions. Therefore, we suggest that the management for decreasing the grip force is meaningful to prevent the occurrence of Hand-arm vibration syndrome (HAVS).

Kinematic characteristics of grip force in patients with cervical spondylosis

Lee, Bumsuk,Noguchi, Naoto,Kakiage, Daiki,Yamazaki, Tsuneo korean Academy of Physical Therapy Rehabilitation 2015 Physical therapy rehabilitation science Vol.4 No.2

Objective: The aim of this study was to objectively evaluate sensory disturbance in cervical spondylosis using grip force and investigate the relationship between the grip force and upper extremity function. Design: Cross-sectional study. Methods: Eleven cervical spondylosis patients with paresthesia conducted grip and lift tasks using a precision grip with the tips of the thumb and index finger on either side. The sum of the grip force used during the first four seconds was calculated and defined as the total grip force. The cutaneous pressure threshold of the fingers, the pinch power, the grip power and three subtests of the Simple Test for Evaluating Hand Function (STEF) were also assessed. Correlations between the total grip force and cutaneous pressure threshold, pinch power, grip power, and STEF subtest times were evaluated. Results: We found that the total grip force correlated with the cutaneous pressure threshold (p<0.05). Moreover, the total grip force of the dominant thumb correlated with the results of the three STEF subtests (p<0.05). There were no significant correlations between the total grip force and pinch/grip powers. Conclusions: We found that the total grip force correlated with cutaneous pressure threshold and upper extremity function. The results suggest that the total grip force could serve as an objective index for evaluating paresthesia in cervical spondylosis patients, and that the impaired ability of the upper extremity function is related to grip force coordination.

Original Article : Kinematic characteristics of grip force in patients with cervical spondylosis

( Bum Suk Lee ),( Naoto Noguchi ),( Daiki Kakiage ),( Tsuneo Yamazaki ) 물리치료재활과학회 2015 Physical therapy rehabilitation science Vol.4 No.2

Objective: The aim of this study was to objectively evaluate sensory disturbance in cervical spondylosis using grip force and investigate the relationship between the grip force and upper extremity function. Design: Cross-sectional study. Methods: Eleven cervical spondylosis patients with paresthesia conducted grip and lift tasks using a precision grip with the tips of the thumb and index finger on either side. The sum of the grip force used during the first four seconds was calculated and defined as the total grip force. The cutaneous pressure threshold of the fingers, the pinch power, the grip power and three subtests of the Simple Test for Evaluating Hand Function (STEF) were also assessed. Correlations between the total grip force and cutaneous pressure threshold, pinch power, grip power, and STEF subtest times were evaluated. Results: We found that the total grip force correlated with the cutaneous pressure threshold (p<0.05). Moreover, the total grip force of the dominant thumb correlated with the results of the three STEF subtests (p<0.05). There were no significant correlations between the total grip force and pinch/grip powers. Conclusions: We found that the total grip force correlated with cutaneous pressure threshold and upper extremity function. The results suggest that the total grip force could serve as an objective index for evaluating paresthesia in cervical spondylosis patients, and that the impaired ability of the upper extremity function is related to grip force coordination.

MFFM System을 이용한 손가락 별 파지 폭들의 변화에 따른 악력 및 개인 선호도에 대한 연구

김대민(Dae Min Kim),공용구(Yong?Ku Kong) 대한인간공학회 2008 大韓人間工學會誌 Vol.27 No.3

Individual finger/total grip forces, and subjective preferences for various individual finger grip spans (i.e., four fingers had identical grip spans or different grip spans) were evaluated by using an "Adjustable Multi-Finger Force Measurement (MFFM) System". In this study, three grip spans were defined as follows: a 'favorite grip span' which is the span with the highest subjective preference; a 'maximum grip span' which is the span with the highest total grip force; a 'maximum finger grip span' which is a set of four grip spans that had maximum finger grip forces associated with the index, middle, ring, and little fingers, respectively. Ten males were recruited from university population for this study. In experiment I, each participant tested the maximum grip force with five grip spans (45 to 65㎜) to investigate grip forces and subjective preferences for three types of grip spans. Results showed that subjective preferences for grip spans were not coincidence with the performance of total grip forces. It was noted that the 'favorite grip span' represented the lowest total grip force, whereas the 'maximum finger grip span' showed the lowest subjective preferences. The individual finger forces and the average percentage contribution to the total finger force were also investigated in this study. The findings of this study might be valuable information for designing ergonomics hand-tools to reduce finger/hand stress as well as to improve tool users' preferences and performance.

수공구 손잡이 형태에 따른 청ㆍ노년층의 악력과 손가락 힘 및 편안함 분석

공용구(Yong?Ku Kong),손성태(Seong?Tae Sohn),김대민(Dae?Min Kim),정명철(Myung?Chul Jung) 대한인간공학회 2009 大韓人間工學會誌 Vol.28 No.2

The purpose of this study was to evaluate aging (young and old), gender (male and female), and handle shape effects on grip force, finger force, and subjective comfort. Four handle shapes of A, D, I, and V were implemented by a multi-finger force measurement (MFFM) system which was developed to measure every finger force with different grip spans. Forty young (20 males and 20 females) and forty old (20 males and 20 females) subjects participated in twelve gripping tasks and rated their comfort for all handles using a 5-point scale. Grip forces were calculating by summation of all four forces of the index, middle, ring and little fingers. Results showed that young males (283.2N) had larger gripping force than old males (235.6N), while young females (151.4N) had lower force than old females (153.6N). Young subjects exerted the largest gripping force with D-shape due to large contribution of the index and middle fingers and the smallest with A-shape; however, old subjects exerted the largest with I-shape and the smallest with V-shape due to small contribution of the ring and little fingers. As expected, the middle finger had the largest finger force and the little finger had the smallest. The fraction of contribution of index and ring fingers to grip force differed among age groups. Interestingly, young subjects provided larger index finger force than ring finger force, whereas old subjects showed that larger ring finger forces than index finger force in the griping tasks. In the relationship between performance and subjective comfort, I-shape exerting the largest grip force had less comfort than D-shape producing the second largest grip force. The findings of this study can provide guidelines on designing hand tool handle to obtain better performance as well as users' comfort.

The Effects of Direction on the Maximal Grip, Pusing, Pulling, and Twisting Forces

Jangwhon Yoon,Ali Shiekhzadeh,Dan Formosa,Scott Shim 대한인간공학회 2012 대한인간공학회 학술대회논문집 Vol.2012 No.11

Objective: The aims of this study were to understand the effects of task direction on the output (pushing, pulling, and clockwise and counter clockwise twisting) and the maximal grip forces and to explore the relationship between the grip and the output forces. Background: Thoughtful handle design improves the productivity and prevents the work-related musculoskeletal disorders. Method: Eighteen healthy volunteers without any history of neuromuscular disorders were recruited. A custom-made handle and a load cell measured the grip force and the output for three seconds. Force measurements along the vertical, coronal and sagittal axes were randomly repeated three times and averaged. The data were analyzed using the repeated measures ANOVA for the effects of task direction on the output and the maximal grip forces and simple linear regression for the relationship between the grip and the output forces. Results: There was no significant effect of direction on the output and grip forces. The pulling force was greatest and the pushing force was smallest in all directions. The order of grip force was pushing, pulling, clockwise twisting, and counter clockwise twisting in all directions. The output and grip forces were highly correlated in all directions. The regression coefficient of grip force was greatest in pulling and smallest in clockwise twisting. Conclusion: Findings of this study suggests that a smart handle design can improve the productivity more in pushing and pulling than twisting tools. Application: It can be valuable information for product designers to develop more productive hand tools and to prevent the musculoskeletal disorders in the upper extremities.

Evaluation of the Contributions of Individual Finger Forces in Various Submaximal Grip Force Exertion Levels

Yong-Ku Kong,Inseok Lee,Juhee Lee,Kyungsuk Lee,Kyeong-Hee Choi 대한인간공학회 2016 大韓人間工學會誌 Vol.35 No.5

Objective:The aim of this study is to evaluate contributions of individual finger forces associated with various levels of submaximal voluntary contraction tasks. Background: Although many researches for individual finger force have been conducted, most of the studies mainly focus on the maximal voluntary contraction. However, Information concerning individual finger forces during submaximal voluntary contraction is also very important for developing biomechanical models and for designing hand tools, work equipment, hand prostheses and robotic hands. Due to these reasons, studies on the contribution of individual finger force in submaximal grip force exertions should be fully considered. Method: A total of 60 healthy adults without any musculoskeletal disorders in the upper arms participated in this study. The young group (mean: 23.7 yrs) consisted of 30 healthy adults (15 males and 15 females), and the elderly group (mean: 75.2 yrs) was also composed of 30 participants (15 males and 15 females). A multi-Finger Force Measurement (MFFM) System developed by Kim and Kong (2008) was applied in order to measure total grip strength and individual finger forces. The participants were asked to exert a grip force attempting to minimize the difference between the target force and their exerted force for eight different target forces (5, 15, 25, 35, 45, 55, 65, and 75% MVCs). These target forces based on the maximum voluntary contraction, which were obtained from each participant, were randomly assigned in this study. Results: The contributions of middle and ring fingers to the total grip force represented an increasing trend as the target force level increased. On the other hand, the contributions of index and little fingers showed a decreasing trend as the target force level increased. In particular, Index finger exerted the largest contribution to the total grip force, followed by middle, ring and little fingers in the case of the smallest target force level (5% MVC), whereas middle finger showed the largest contribution, followed by ring, index and little fingers at the largest target force levels (65 and 75% MVCs). Conclusion: Each individual finger showed a different contribution pattern to the grip force exertion. As the target force level increase from 5 to 75% MVC, the contributions of middle and ring fingers showed an increasing trend, whereas the contributions of index and little fingers represented a decreasing trend in this study. Application: The results of this study can be useful information when designing robotic hands, hand tools and work equipment. Such information would be also useful when abnormal hand functions are evaluated.

Development of DFM(Double-Handle Force Measurement) System For Measuring Individual Finger Forces

Yong Ku Kong,Dae Min Kim,Cheol Min Lim,Min Tae Seo 대한인간공학회 2011 대한인간공학회 학술대회논문집 Vol.2011 No.10

Objective: The purpose of this study was to develop DFM(Double-handle Force Measurement) System for measuring grip strength and individual finger force. Background: A handle shape has not been considered in man previous studies of grip strengths. Accordingly, Design of double-handle tools on ergonomic aspect have many limitations. Methods: In this study, five grip span of A-type was used for measuring total grip force, individual finger force, and finger force distributions. Ten males were recruited from University population for this study. Each participants were asked to exert their maximum grip strength with 3 repetitions for five grip spans(45, 50, 55, 60, 50mm). Results: The highest grip strength was performed on 45mm and 50mm grip spans. On the other hand, among the entire finger, middle and ring fingers showed the highest force as well as distribution to the total finger force. Discussions: The findings of this study might be important information, basically, for designing ergonomic doublehandle tool type.

Effect of Task Direction on the Maximal Pushing, Pulling, Twisting, and Grip Forces

Jangwhon Yoon 대한인간공학회 2016 大韓人間工學會誌 Vol.35 No.5

Objective:The aims of this study are to understand the effects of task (pushing, pulling, and clockwise and counter clockwise twisting) direction on the maximal output and their grip forces and to explore the relationship between the maximal output and the grip forces. Background: Knowing the normative maximal grip force is not enough to design a good hand tool. The industrial designers should understand the required grip forces in various motions toward a specific direction to make an effective and efficient hand tool. Method: Eighteen healthy volunteers participated in the series of isometric maximal output force tests. A custom-made force measuring equipment collected the output and the grip forces for three seconds. Force measurements along the vertical, coronal and sagittal axes were randomly repeated three times. Results: The pulling was strongest and the pushing was weakest in all directions. The effect of motion on the output forces varied in different directions. The corresponding grip force increased in the order of pushing, pulling, clockwise twisting, and counter clockwise twisting in all directions. The maximal output and their grip forces were highly correlated but the relationship was affected by motion and direction. The regression coefficient was greatest in pulling and smallest in clockwise twisting. Conclusion: The effect of motion on the output forces varied in different directions. The maximal output and their grip forces were correlated but the relationship was affected by motion and direction. Application: Findings of this study can be valuable information for industrial designers to develop more productive hand tools and work stations to help preventing the musculoskeletal disorders at work.

BT50용 스핀들 공구 파지력 검사를 위한 힘센서 개발

이대건 ( Dae-geon Lee ),김갑순 ( Gab-soon Kim ) 한국센서학회 2021 센서학회지 Vol.30 No.1

In this paper, we describe the development of a force sensor to measure the tool gripping force of the BT50 spindle. The force sensor for a BT50 must be installed inside the gripping force tester; hence, it must be of an appropriate size and have a rated capacity suitable for measuring the gripping force. So, the structure of the force sensor for BT50 was modeled, the size of the sensing part was determined by structural analysis, and the force sensor was manufactured by attaching a strain gauge. The characteristic test results of the manufactured force sensor, indicated that the nonlinearity error, hysteresis error, and reproducibility errors were each within 0.91%, Therefore it was determined that the manufactured force sensor can be used for checking the spindle tool gripping force.