• Journal of the Korean Society of Safety
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• v.20 no.2 s.70
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• pp.127-132
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• 2005

The purpose of this study is to compare representative posture classification schemes of OWAS, RULA and REBA in terms of correctness for postural load. The comparison was based on the evaluation results by the three methods for 224 working postures sampled from steel, electronics, automotive, and chemical industries. The results showed that OWAS and REBA generally underestimated postural stress than RULA irrespective of industry type, work performed and whether or not leg posture is balanced. While about $71\%\;and\;73\%$ of the 224 posture were evaluated with the action category/level 1 or 2 by OWAS and REBA respectively, about $60\%$ of the postures were classified into the action level of 3 or 4 by RULA. The coincidence rate of postural stress category between OWAS and RULA was just $33.5\%$, while the rate between RULA and REBA was $46.0\%$. It is concluded from the findings of this study and the previous research that compared to OWAS and REBA, RULA more precisely evaluates postural stress.

• Journal of the Ergonomics Society of Korea
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• v.22 no.3
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• pp.57-73
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• 2003

Although body pressure distribution is sensitive to movements and is relatively simple to measure even in small space, there are few researches involving applications to driver's posture and its change. The main objective in this study is the application of body pressure distribution measurements for the prediction of the driver's posture and its change. This requires quantitative analyses of the dynamic body pressure distribution, which is the change of body pressure distribution with time. The experiment involved 16 male subjects who drove for 45 minutes in a seating buck. Measurement time, stature group, and lumbar support prominence were selected as independent variables, with subjective ratings of driver's discomfort, body posture data of hip, torso. knee angle, and body pressure data variables as dependent variables. The body pressure change variables and subjective ratings were found to increase as the measurement time increased and body pressure ratio variables reflected the torso angle. From the results and analysis of the body posture data and subjective rating results, it was predicted that the seats and the design of the lumbar supports used in the experiment was not fit for tall subjects, which could also be confirmed through the body pressure distribution data.

• International Journal of Clinical Preventive Dentistry
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• v.14 no.4
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• pp.235-240
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• 2018

Objective: The purpose of this study is to examine about dental hygienists' myofascial pain syndrome, lower back pain, carpal tunnel syndrome (CTS), medial and lateral epicondylitis, hand-arm vibration syndrom and work-related musculoskeletal syndrome (WMSD) experience and hygienists' posture, motion. Methods: The self-administered questionnaire was surveyed from June 1 to September 30 of 2018 targeting 280 dental hygienists in Gyeongnam province and 266 dental hygienists' answers were analyzed. Results: The average daily working hours of a dental hygienist was more than eight hours 59.0%, with an average of 33 patients per day. The average number of patients who receive treatment for more than 30 minutes is 15. The angle of motion of the subjective evaluation was above 60%. Medical position and form of movement were more than 50% above the standard level. Symptoms of posture and motion that cause WMSD were hand-arm vibration syndrome 68.1%, myofascial pain syndrome 58.6%, lower back pain 51.1%, CTS 50.4% in order. Experience WMSD related symptoms which dental hygienists experience were myofascial pain syndrome 92.9%, CTS 57.9%, lower back pain 56.4%, medial and lateral epicondylitis 37.2%, hand-arm vibration syndrome 24.4%. Conclusion: The above results showed the posture and motion of dental hygienists and were found that the experience rate which dental hygienists experience WMSD of myofascial pain syndrome, Lower back pain, and CTS was significantly more than 56%.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.341-346
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• 2013

Purpose: The purpose of this study was to evaluate whether a relationship exists between head posture and phoria, and usefulness in examining habitual head posture. Methods: Twenty two subjects (20 males and 2 females, mean age $23.6{\pm}2.7$ years) with abnormal phoria from participants randomized were enrolled in this study. For all subjects, testing included case history, cover test, refraction, phoria and vergence test. Habitual head posture (head posture, head tilt and face turn) was measured by Impression IST, and observed by examiners. Results: The abnormal head posture was revealed in some subjects with abnormal phoria. Spearman' correlation ($\rho$=0.524, p=0.045) showed significant correction between face turn and phoria at distance in 15 subjects with prism prescription. No significant relationship between head posture and phoria was found in subjects with abnormal phoria. The objective measurement and subjective observation of head posture showed insignificant correction but there was a distinct difference. The former was detail and the latter was discriminate. Conclusions: Presence of abnormal head posture was found in phoric subjects. The results indicate the need to observe habitual head posture at all major positions of gaze in phoria.

• Journal of the Ergonomics Society of Korea
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• v.31 no.2
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• pp.281-289
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• 2012

Objective: The purpose of this study is to evaluate the potential risk of shoulder muscle at particular working postures in sitting. Background: The cause of shoulder pain needs to be specifically studied in relation with particular shoulder postures to prevent shoulder MSDs in workplace. Method: In this study MVC, fatigue and subjective workload were investigated depending on the change of shoulder posture. An experiment was designed to evaluate the six shoulder muscles at nine shoulder postures including the combination of 30(adduction), 0, 30(abduction) degrees and 60, 90, and 120 degrees of shoulder flexion. Surface electrodes were attached to the middle trapezius, inferior middle trapezius, anterior deltoid, posterior deltoid, serratus anterior and teres major. Thirteen subjects participated in the experiment. Dependent variables were RPE (rating of perceived exertion), MVC(maximum voluntary contraction) and MPF(mean power frequency) shift by EMG (electromyography). Results: The middle trapezius and inferior middle trapezius were not significantly fatigued at all postures. The decline of MPF slope was less than 10% at all postures. The anterior deltoid was significantly fatigued all postures. The decline of MPF slope was more than 10% at all postures. The posterior deltoid was significantly fatigued 30 degrees of adduction and 90 degrees of flexion. And, neutral and 30 degrees of abduction postures were fatigued more than 90 degrees of flexion. The serratus anterior was significantly fatigued except for 30 degrees of adduction and 60 degrees of flexion posture. The teres major was significantly fatigued except for neutral and 60 degrees of flexion, 30 degrees of abduction and 60 degrees of flexion posture. Conclusion: It was found that a certain muscle was fatigued fast at particular posture compared to other muscles, which would mean that a certain shoulder muscle at particular posture could be easily exposed to the risk of musculoskeletal disorders than other muscles. Application: It is expected that the result can be applied to design workplace using shoulder muscles.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.20 no.2
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• pp.15-20
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• 2014

Objective: The purpose of this study was to investigate the effects of sling exercise on the cervical lordotic angle, craniovertebral angle, and head rotation angle among adolescents in the forward head posture. Methods: The subjects include 22 adolescents that recorded a mild level or higher on the posture evaluation index by New York State. They were randomly divided to the hand exercise group (n=11) and the control group (n=11). The former group participated in the sling exercise program three times a week over four weeks in total with each session lasting 60 minutes, whereas the latter group was not included in the program. The cervical lordotic angle, craniovertebral angle, and head rotation angle were measured before and after the intervention. Results: The study compared the cervical lordotic angle between the two groups before and after sling exercise and found that the sling exercise group made an increase of $7.36^{\circ}$ from $21.91^{\circ}$ to $29.27^{\circ}$ after the intervention(p<.05). As for the comparison results of the craniovertebral angle, the sling exercise group made an increase of $5.64^{\circ}$ from $48.91^{\circ}$ to $54.55^{\circ}$ after the intervention (p<.05). As for the comparison results of the cranial-rotation angle, the sling exercise group made an decrease of $-7.73^{\circ}$ from $148.82^{\circ}$ to $141.09^{\circ}$ after the intervention (p<.05). The control group showed no differences before and after the intervention (p>.05). Conclusion: Those findings indicate that the application of sling exercise in the forward head posture can be a good program to maintain the right posture and improve or prevent an abnormal posture and raise a need for more clinical applications and ongoing researches.

• Journal of the Korean Society of Safety
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• v.24 no.2
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• pp.83-88
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• 2009

The objective of this paper was to evaluate the effectiveness of horizontal, vertical, asymmetric and coupling multipliers for manual material handling. Lifting tasks with 5 different horizontal distances ($30{\sim}70cm$) for 6 vertical distances(ankle, knee, waist, elbow, shoulder and head height) were experimented. The muscle activity and muscle exertion level during asymmetric load handling(without trunk flexion) was experimented. Lifting tasks with and without handle tote box for three postures(straight, bending, right angle posture) were experimented. The degrading tendency did not appeared almost in $60{\sim}70cm$ interval's horizontal distance. As a result of ANOVA, MVC paid attention to horizontal and vertical distance but cross effect was insignificant(p<0.01). The change of the MVC according to the horizontal, vertical distance appeared similar from of RWL. The results of normalized MVC measurement were decreased about 16%, 24%, 34% respectively as the asymmetry angle was $30^{\circ}$, $60^{\circ}$, $90^{\circ}$. RMS EMG values of right erector spinae muscles were decreased as the work posture went to $90^{\circ}$ and those of left erector spinae muscles were increased until the asymmetry angle was $40^{\circ}$ but decreased continually over $40^{\circ}$. 7 subjects, activities of left and right latissimus dorsi muscles were maintained constantly, while for remainer, those were irregular. MVC reduced maximum 23% by type of handle. MVC was highest in straight posture, but was lowest in right angle posture. As a result of ANOVA, MVC paid attention to posture, coupling(p<0.01). To all handle types, biceps brachii activity was increased in right angle posture, but reduced in straight posture. Based on the results of this study, it is suggested that the NIOSH guideline should not be directly applied to Korean without reasonable reexamination. In addition, we need to afterward study through an age classification.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.9-14
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• 2022

In this study, we propose a method for moving a device such as a flexible air sculpture while stably maintaining the user's desired posture. To accomplish this, a robot system with a structure of a mobile robot capable of running according to a given trajectory was studied by applying the PI algorithm and horizontal maintenance posture control using IMU. The air sculptures used in this study often use thin strings in a fixed posture. Another method is to put a load on the center of gravity to maintain the posture, and it is a system with flexibility because it uses air pressure. It is expected that these structures can achieve various results by combining flexible structures and mobile robots through the convergence process of digital sensor technology. In this study, posture control was performed by fusion of the driving technology of AGV(Automatic Guided Vehicle),, a field of robot, and technologies applying various sensors. For verification, the given performance evaluation was performed through an accredited certification test, and its validity was verified through an experiment.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.596-605
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• 1994

An efficient measurement and evaluation system for hand tool tasks will provide a practical solution to the problem of designing and evaluating manual tool tasks in the workplace. Few studies on the biomechanical analysis of hand postures and tool handling tasks exist because of the lack of appropriate measurement techniques for hand force. A measurement system for the finger forces and joint angles for analysis of manual tool handling tasks was developed in this study. The measurement system consists of a force sensing glove made from twelve Force Sensitive Resistors and an angle-measuring glove (Cyberglove$\^$TM/, Virtual technologies) with eighteen joint angle sensors. A biomechanical model of the hand using the data from the measurement system was also developed. Systems of computerized procedures were implemented integrating the hand posture measurement system, biomechanical analysis system, and the task analysis system for manual tool handling tasks. The measurement system was useful in providing the hand force data needed for an existing task analysis system used in CTD risk evaluation. It is expected that the hand posture measurement developed in this study will provide an, efficient and cost-effective solution to task analysis of manual tool handling tasks. These tasks are becoming increasingly important areas of occupational health and safety of the country.

• The Journal of Korean Physical Therapy
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• v.5 no.1
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• pp.9-15
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• 1993

The purpose of this study was to describe the difference of weight distribution between healthy persons and low back pain patients during normal standing posture and to help the evaluation of weight bearing. 30 healthy persons and 30 low back pain patients being treated as hospitals in Taegu area participated in this study. The results were 2.63kg id the difference of weight distribution of healthy group and 3.04kg in low back pain group. This study was not significantly different between healthy and low back pain group.