• Journal of the Ergonomics Society of Korea
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• v.28 no.3
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• pp.41-47
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• 2009

The purpose of this study, during the lifting task was researching the difference and a relationship between the ground reaction force and the grip strength by change of position. After grip strength has measured in symmetry position and asymmetry position at 45cm and 75cm of height of hand, ground reaction force was measured by same attitude lifting wooden box. We analyzed the difference of grip strength and ground reaction force in each position change. The results of grip strength, the grip strength of both hand were significant difference that in study subject symmetry and asymmetry position (p<0.01). The results of symmetry lifting task, the study subjects was significant difference of the ground reaction force difference by height (p<0.05). Asymmetry lifting task was significant difference of ground reaction force difference by direction of rotation was changed (p<0.01). The result of it will rotate with non-dominant hand side of lifting tasks from height 75cm where it easily maintains a balance possibility and decreasing the load of the hand. Therefore, from the workshop in the work people, it will be between the height 75cm and non-dominant hand side of trunk rotatory direction in the lifting tasks. Future study is necessary researched about the change of grip strength when the height of the hand is higher, and the difference of the ground reaction force when the change of weight.

• PNF and Movement
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• v.20 no.1
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• pp.73-81
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• 2022

Purpose: The aim of this study was to present specific criteria for setting goals for hand rehabilitation by comparing the degree of difference in grip force, coordination, and dexterity between the dominant and non-dominant hand according to gender. Methods: We recruited 100 healthy adults in their 20s and 30s. A handheld digital dynamometer was used to evaluate the grip force of each of the dominant and non-dominant hand, a chopsticks manipulation test was used to evaluate coordination, and the Purdue Pegboard test was used to evaluate agility. Results: In all subjects, the grip force, coordination, and dexterity showed statistically significant difference (p <0.01) between the dominant and non-dominant hand. In the comparison according to gender, both male and female dominant and non-dominant hands showed statistically significant differences in grip force, coordination, and dexterity (p <0.01). In the comparison according to grip force, there was a statistically significant difference between the dominant and non-dominant hand, and men showed stronger result values in both hands compared to women (p <0.01). In the comparison according to coordination, there was no statistically significant difference between the dominant and non-dominant hand in men and women (p >0.05). In the comparison according to dexterity, there was a statistically significant difference between the dominant and non-dominant hand, and women were shown to be faster in performance time with both hands, compared to men (p <0.01). Conclusion: Differences according to gender exist in grip force and dexterity but not coordination, and differences between dominant and non-dominant hand exists across all measurements. The results suggest setting a recovery goal according to dominance and gender during rehabilitation of hand function.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.125-131
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• 2007

The purpose of this study was to evaluate the difference in grip force and angular kinematic variables between elite (handicap${\leq}2$) and novice golfers. Three-dimensional motion analysis system with synchronized grip force measurement system was used. The participants consisted of two groups based on their playing ability: 10 elite golfers and 10 novice golfers. Each subject performed 5 putting strokes at the distance of 1, 3, and 5m with randomly selected order. During entire putting phase, elite group showed relatively constant grip force but novice group showed continuously increasing grip force pattern. There existed a clear difference in the trajectory of shoulder line between two groups. As for novice group the rotational center did not converge into one point, for elite group the rotational center converged into precise single point. And there was a clear difference pattern in anterior-posterior directional movement at shoulder between two groups. These difference might be helpful for improving consistent putting skills.

• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.569-578
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• 2017

Objective: The purposes of this experiment are an analysis of accuracy between target force level and subjective rating for the Target Force Level and an analysis of the patterns of subjective rating depending on target force level when there is no feedback from males for analysis. Background: The study of perceived exertion about the static contraction is processed with using among the matching procedure method between contralateral limbs, Exertion vs. Borg CR-10 scale and Exertion vs. %MVC (Maximum Voluntary Contraction). However, when there is no feedback, there is lack of the study on whether the subject can distinguish the subjective rating of the force depending on the target force levels. Method: Total 30 males, healthy subjects are measured the maximum grip strength, MVC, and then, each subject is measured the subjective rating and the accuracy with the random target force level (10, 20, 30, 40, 50, 60, 70, 80, and 90% MVC). Results: In the MVC study, males exerted 256.87N (${\pm}51.33$). In the subjective rating of grip strength increased for each Target Force Level (9 levels), higher subjective rating evaluated (p<0.05). In accuracy examination between target force level and subjective rating of grip strength by each %MVC, 10, 30, 40, 50, 70, 90% target force levels showed accurate strength (p>0.05). However, at 20% target force level, the subjects evaluated less subjective rating of grip strength than the target force (Underestimation), and at 60% and 80% target force level, the subjects evaluated more subjective rating of grip strength than the target force (Overestimation) (p<0.05). Conclusion: In the experiment, the MVC showed 256.87N (${\pm}51.33$) for the male adults and as the subjective rating value increased for each Target Force Level (9 levels), higher subjective rating evaluated (p<0.05). Moreover, the results of the accuracy test between target forces and subjective rating of the subjects showed that most participants rated a fairly accurate assessment of subjective rating of grip strength for Target Force Level (9 levels), except for 20%, 60%, and 80%MVC. Application: This experimental result would be used for basic data for the subjective rating of grip strength pattern by the target force level when the voluntary muscle is contracted.

• Journal of the Ergonomics Society of Korea
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• v.35 no.5
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• pp.361-370
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• 2016

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.

• Physical Therapy Korea
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• v.27 no.2
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• pp.118-125
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• 2020

Background: Lateral epicondylitis (LE) is the most common chronic musculoskeletal pain condition of the upper extremities. LE is often related to forceful grip activities that require isometric contraction of the wrist extensors. A previous study evaluated the effect of the diamond taping technique on grip strength and pain; however, there has been no report on the change in the electromyography (EMG) findings of wrist extensors. Objects: The aim of this study was to investigate the effect of diamond taping technique, using a rigid tape, on the EMG activities of the extensor carpi radialis (ECR) during grip activities. Methods: Twenty-four healthy subjects (mean age = 21.50 ± 2.76 years) volunteered to participate in this study. The subjects were instructed to perform forceful grip activities with and without diamond-type taping on the origin area of the ECR. Grip strength tests were performed at 100%, 75%, 50%, and 25% for maximal isometric contraction force. EMG data were collected from the ECR. Repeated measure analysis of variance was used to analyze the effect of grip force and taping (with and without). Statistical significance levels were set at α = 0.05. Comparison of the results with and without taping at different grip force were analyzed using independent t-test. Statistical significance levels were set at α = 0.01. Results: Statistically significant association was observed between the taping application and forceful grip activity as revealed by the EMG data of the ECR (p < 0.05). EMG of the ECR significantly reduced for all muscle strength levels (p < 0.01) after taping. Conclusion: This study shows an impressive effect of the diamond taping technique, using rigid tape, on wrist extensors during grip activities. Decreasing muscle activity via this taping approach could be utilized to enhance pain-free grip force and reduce pain in patients with LE. Our study suggested that this taping technique could be considered as an effective management strategy of LE.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.4 s.97
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• pp.404-411
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• 2005

To increase accurateness and reliability of the evaluation of power tool vibration transmitted to an operator, it is necessary to measure the grip and feed forces during the measurement of hand-transmitted vibration. In the study a system was invented to measure the vibration and the grip and/or feed force, which consists of a measurement handle and a PC with a data acquisition system and the corresponding software. Strain gauges and an accelerometer were mounted on the handle surface for the simultaneous measurement of the forces and the vibration. The program in the system makes it possible to monitor the grip and feed force during the tool operation so that the operator keeps the applying forces within the pre-determined range. Investigating the vibration total values, frequency-weighted root-mean-square accelerations at the handle, obtained in repetition for each power tool with control of the grip and feed force showed more consistency than those measured without force control. By using the system the experimenter can reduce random error of the measured vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.689-694
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• 2004

To increase accurateness and reliability of the evaluation of power tool vibration transmitted to an operator, it is necessary to measure grip and feed forces during the measurement of hand-transmitted vibration. In the study a system was invented to measure the vibration and the grip and/or feed force, which consists of a measurement handle and a PC with data acquisition system and the software. Strain gauges and an accelerometer were mounted on the handle for the simultaneous measurement of the forces and the vibration. The program in the system makes it possible to monitor the grip and feed force during the tool operation so that the operator keeps the applying forces within the pre-determined range. Investigating the vibration total values, frequency-weighted root mean square accelerations at the handle, obtained at various conditions with control of the grip and feed force showed more consistency than those measured without force control. By using the system the experimenter can reduce uncertainty of the measured vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.1038-1042
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• 2003

In order to evaluate dynamic impedance of a hand-arm system it is necessary to measure the hand-transmitted vibration and the reaction force at the same time while gripping the vibrating handle. In the study a device was developed to measure both the vibration and the force. The device consists of a measurement handle with four strain gauge and two accelerometers and a PC based control system with a program for the signal processing and evaluation of the hand-transmitted vibration and reaction force. The handle was installed on the vibration shaker so that it can move by the generated signal from the control system. As an application of the system dynamic reaction force and the frequency weighted acceleration at the handle attached to the shaker were measured at various grip force and feed force. This system will be very useful in the area of impedance measurement and the evaluation of performance of anti-vibration gloves.

• Korean Journal of Applied Biomechanics
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• v.15 no.2
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• pp.113-117
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• 2005

As a preliminary study of finding the relationship between the force at the grip and the success rate during putting stroke, the putting grip sensor system using FSR sensors was developed. The system consisted of the hardware which had the sensor part with 8 sensors per putting glove and data acquisition part as well as the software which had the real-time monitoring program and the offline post-processing program. After experiments with elite-golfer using this system, it is possible to suggest the proper force ranges at the grip during putting stroke.