• Journal of the Ergonomics Society of Korea
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• v.32 no.6
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• pp.511-516
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• 2013

Objective: The objective of this study is designing an optimal hand tool through maximum grip force study accordance to the hand grip span. Background: In order to prevent musculoskeletal diseases, studies on hand tool design are proceeding based on grip strength, finger force, and contribution of individual finger force on total grip strength. However, experimental apparatus using a tool that is actually used in work place was almost non-existent. Method: 19 males were participated in an experiment. Using the load cell inserted real plier, finger force, grip strength, and subjective discomfort rate of both hands (dominant and non-dominant) were measured in 5 different hand grip span(45mm, 50mm, 60mm, 70mm, and 80mm). Results: There was significant difference(p<0.001) of total grip strength, individual finger force and subjective discomfort rating according to various hand grip span(45, 50, 60, 70, and 80mm). Also, statistically significant different(p<0.001) was shown between the dominant hand and non-dominant hand. In addition, individual finger force in maximum grip was in order of middle finger, ring finger, index finger, and little finger. Conclusion: Optimal grip span of pliers that exerting maximum grip strength is 50~60mm. Application: This finding is expected to be used for designing proper pliers.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.3
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• pp.77-86
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• 2019

The purpose of this study was to reveal how the agility of fingers directly involved in the use of mobile phones, a necessity for modern people, is related to the amount of text usage. To find out, 95 people who agreed to the purpose of this research without any limitation on visual and upper-geometry were selected. The research period was from June 27, 2018 to July 31, 2018. The evaluation tool used in this study was Grooved Pegboard, a standardized evaluation tool that measures hand dexterity, and the general characteristics of examinees such as age, text message amount, and a hand that using for text messages were investigated through interviews. Since text input methods vary depending on mobile phone types, unfamiliar methods of typing mobile phone characters can affect the speed of texting. As a result, there were significant differences in hand dexterity between age and gender. The rate of texting and hand dexterity were statistically significantly faster than those in their 20s and 30s (p<0.05), and in gender, women showed significantly faster texting and hand dexterity than men (p<0.05). However, it was not statistically significant to text usage and to the dexterity of the hand.

• Journal of the Ergonomics Society of Korea
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• v.26 no.1
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• pp.29-37
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• 2007

This study was performed to evaluate the characteristics of transmitted vibration to hand-arm system under different work posture while operating a light-weighted powered hand grinder. For the experiment, 8 different types of wrist posture (natural, unlar-flexion, radual-flexion, flexion, extension, complex posture, and etc.) and 3 types of feed force (20[N], 50[N], 70[N]) were considered. 10 male subjects were employed to polish metal plate with a hand grinder. All of them were normal and healthy with no history and symptom of the work related musculoskeletal disorders in the dominant hand. Vibration acceleration data were recorded with sampling rate, 2048[Hz]. In addition, unweighted overall R.M.S. acceleration at the tool and wrist, and transmissibility between them were used to evaluate factors from the recorded tri-axial vibration acceleration. The results indicate that transmissibility of natural wrist posture was significantly higher than others. In addition, as the feed force becomes larger, the vibration was transmitted in large quantities to hand-arm system through radius.

• 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.

• The Transactions of the Korea Information Processing Society
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• v.6 no.12
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• pp.3435-3446
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• 1999

The application of Computer Aided Design (CAD) tool to rehabilitative surgery of the hand is a new field of endeavor. It is considered that there are currently no existing systems designed to assist the orthopedic surgeon in planning complex procedures such as tendon transfer operations. Most tendon transfer operations are performed by surgeons on the basis of knowledge and experience gained through years of practice. However, with the help of this computer graphics-based CAD tool for planning tendon paths, the planning and the evaluation for the best operation on patients' hands also may be possible. The purpose of this study was to model kinematically the structure of the hand and design a prototype tendon path planning tool with a standard computer graphics library, in order for surgeons to perform tendon transfer surgery more objectively and quantitatively.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.2
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• pp.103-114
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• 2023

Objectives: This study was conducted to evaluate hand-arm vibration (HAV) exposure levels due to the use of power hand tools and to evaluate the determinants in the automobile assembly process. Methods: The exposure level to HAV was evaluated for 30 work lines in five assembly processes (body, engine, chassis, door, and design) that use air-powered tools and battery-powered tools and operate in circulation for two hours. The 2-hr equivalent energy vibration acceleration, A (2), of the task was measured. The 8-hr equivalent energy vibration acceleration, A (8), was estimated in consideration of the number of tasks that can be performed per day by each process. In addition, a survey on the working environment was conducted with workers exposed to vibration. Results: The geometric mean of the HAV exposure level, A (2), for a total of 30 tasks was 2.51 m/s², and one case was 10.30 m/s², exceeding TLV (2hr). The HAV exposure level of A (8) was evaluated from 1.03 m/s² to 5.36 m/s². A (2) showed a statistically significant difference (P<0.01) for each process, and the chassis process (GM=3.90 m/s²) was the highest. The larger the tool size and the longer the tool length, the higher was the vibration acceleration when using a battery-powered tool than an air-powered tool (P<0.01). Battery-powered tool users showed higher dissatisfaction on all items than did air-powered tool users. Conclusions: As a result of this study, it is necessary to implement a program to reduce the HAV exposure levels.

• Journal of the Korea Society of Computer and Information
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• v.27 no.11
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• pp.165-172
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• 2022

This paper proposes a method to derive the time points for helpful intervention based on conclusions drawn from a previous study which collected data during barista training performed by students with developmental disabilities. To identify this intervention time, this study utilized distance information between the hand of a student and each barista tool in a virtual reality space. If the cumulative distance from a student's hand to the key barista tool is relatively longer than the cumulative distance to other barista tools, it is highly likely that the student is not using the key barista tool, which must be used to successfully complete the given task. In other words, the distance information signals the task is not being properly performed and represents the intervention time to help the student. As a result of verifying a hypothesis through statistical analysis, this study found that the relationship between the success or failure of a student's training and the cumulative distance between the student's right hand and the key barista tool was statistically significant, but not for the left hand.

• Therapeutic Science for Rehabilitation
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• v.2 no.2
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• pp.61-66
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• 2013

Objective : The purpose of this study was to analysis of disparity between bilateral hand movement when performing activity of daily living using accelerometer. Methods : The subjects of this study included 6 healthy adults. The assessment tool used Jebsen Hand Function Test and accelerometer. The subjects performed 7 sub-tests after wearing accelerometer around wrist. Results : Among sub-tests, writing was the only significantly correlated with difference between dominant and non-dominant hand(t=-2.394, p<.05). Further, non-dominant hand (M=2476.2, SD=802.2) showed more movement than dominant hand(M=1456.2, SD=667.6). Conclusion : This results indicated that accelerometer is useful tool for assessment of bilateral hand movement. Considering demographic characteristics, various subject group, further study is needed.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.151-157
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• 1996

Postural tremor of the upper arm in a static posture was measured to provide guidelines of hand tool weight. Three types of camera recording postures were selected. Postural tremor was measured on five levels of tool weights; no weight, 400g, 800, 1200g, and 1600g. For each conditions, upper arm postural tremor was measured together with EMG of biceps, deltoid, and pectoralis major, and Borg's CR-20 scale ratings of perceived exertion. Results of the experiment are as follows; Frequency analysis of tremor revealed that increased amplitude of frequency band of 2-4Hz and 10-14Hz was observed. Postural tremor of the upper arm maintained the initial level until fatigue developed. After the development of fatigue, the rate of the change of postural tremor was significantly increased. Different tool weights and hand postures showed different rate of tremor increase. And time to fatigue and the corresponding endurance time was positively correlated with Borg's RPF scores.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2430-2432
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• 2002

We made a master hand which can be used as tool for getting grasping data. By using the data from the master hand, we analyzed grasping patterns of human hands. Based on this analyzed results, we developed an grasping algorithm for some particular hand actions. To develop the above algorithm, we programmed a 3D simulation S/W using Visual C++. And we made a slave hand to prove the validity of the proposed algorithm.