• IE interfaces
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• v.17 no.2
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• pp.218-225
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• 2004

This study aims to investigate effect of external load and motion repetitiveness on perceived discomfort. An experiment was performed for measuring discomfort scores at varying conditions, in which external load, motion repetitiveness and arm posture were employed as experimental variables. The arm posture was controlled by shoulder flexion and abduction, and by elbow flexion. Fifteen healthy college-age students without history of musculoskeletal disorders voluntarily participated in the experiment. The results showed that the effect of external load, motion repetitiveness and shoulder posture on discomfort were statistically significant, but that elbow posture did not significantly affect discomfort ratings. The effect of external load was much larger than that of any other variables, and that of repetitiveness was second only to external load. Discomfort scores significantly increased linearly as the levels of external load and motion repetitiveness increased. This implies that although they were not fully reflected in the existing posture classification scheme such as OWAS, RULA, etc., the effect of external load and motion repetitiveness should be taken into consideration for precisely quantifying work load in industry. Based on regression analysis, equivalent values of external load and motion repetitiveness in terms of discomfort scores were provided, which would be useful for better understanding the degree of their effect on work load.

• Journal of The Korean Society of Integrative Medicine
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• v.4 no.4
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• pp.83-90
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• 2016

Purpose : Recommended posture according to the location of operating teeth have been standardized in dental clinic to prevent musculoskeletal disorder. However, clinicians do not comply with this rule in many cases. This study investigated the effects of operating posture on cranio-cervical range of motion (CROM) and muscles activity of neck and upper extremity. Methods : Sixteen healthy dental hygiene students were participated. During operating posture (3 recommended and 3 experimental postures which were set front, side, back, respectively), CROM in the fronal and sagittal plane were measured by Cervical Range of Motion Instrument and muscle activities of Sternocleidomastoid, upper trapezius, middle deltoid, extensor carpi radialis, brachioradialis, and abductor pollicis brevis were measured by Pocket EMG system. Result : CROM were significantly decreased in recommended posture in comparison with experimental posture (p<.05). In addition, muscle activity of middle deltoid was significantly decreased in recommended front posture. Moreover, brachioradialis and extensor carpi radialis showed the same result in recommended back posture (p<.05). Conclusion : Recommended posture is close to neutral posture and to reduce muscle fatigue and overuse, which may considered as a preventing musculoskeletal disorder and partially explain its efficacy in dental clinic.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.5
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• pp.688-696
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• 2003

The casing oscillator used for basic construction of buildings, factories and bridges is a construction machine, which rotates and rolls the casing to insert it into the ground. It is very important that the casing is positioned perpendicular to the sea level regardless of the slope of the ground. In this paper, we present a new casing oscillator that doesn't need additional work to level the ground for the casing insertion. The kinematic analysis fur work space of a casing oscillator is presented and carried out with auto-balancing of the casing oscillator using posture feedback control.

• Journal of the Ergonomics Society of Korea
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• v.30 no.4
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• pp.473-480
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• 2011

Objective: This paper presents the results of a literature review undertaken to analyze the types and risk factors of unsafe posture in accordance with the crops and the working position and to introduce various ergonomic intervention approaches. Background: There is clear and consistent evidence that agricultural work has been rated as one of the dangerous occupations in the world. A considerable number of adverse health conditions, including musculoskeletal disorders(MSDs) are related to agricultural work. Method: An agricultural work requires squatting, kneeling, and bending(stooping) postures for significant periods of the work day which due to a wide variety of activities such as planting, cultivating and harvesting various agricultural products. Thus, each of these postures is analyzed in detail to recommend the improvement methods. Results: Various unsafe postures in agricultural works are revealed and analyzed. It is proven that ergonomics intervention has the potential benefits to reduce MSDs among agricultural workers. Two types of ergonomic intervention methods were discussed to improve unsafe working postures, engineering controls and administrative controls. Conclusion & Application: As a concluding remark, this article can be used as a reference manual for the agricultural workers and also used to raise the research community's awareness to the risk of unsafe working postures for workers in agriculture.

• Journal of the Ergonomics Society of Korea
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• v.30 no.5
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• pp.637-644
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• 2011

Objective & Background: When applying various evaluation tools that analyze work posture risk through observation, accurate measurement of body flexion angle is very important. Method: This study investigated differences and appropriateness of 5 different existing reference points commonly used in the analysis of the work posture. Twenty five ergonomist and trained professionals were participated in this study. A Same flexion angle was utilized for the evaluation of risk assessment of musculoskeletal disorders using five different reference points to investigate the degree of difference between them. To investigate how different the observers' preferred flexion angle measuring methods were compared to the ISO 11226 Reference Posture, a virtual body model was constructed using the Poser 6.0 program. Six types of body flexion postures were constructed, and since neck flexion differs according to body angle, five types of neck flexion postures were constructed with the trunk bending $20^{\circ}$ forward, making up a total of 30 virtual flexion postures. Results: Results showed that the observers used personally preferred reference points instead of reference points recommend in the evaluation tools. Also the results revealed the their seems to be 6 types of flexion angle for the trunk and 11 types of measurement methods for the neck flexion angle in the form of personally preferred reference points. The results showed that a mean difference of $14^{\circ}$($4{\sim}23^{\circ}$) occurred in the trunk, and a mean difference of $20^{\circ}$($-8{\sim}51^{\circ}$) occurred in the neck. To increase accuracy when using the 5 evaluation tools in combination, the ISO 11226 standards, observers' preferred flexion posture standards, and common flexion posture standards of the evaluation tools were compared with the reference points of the 5 evaluation tools. Results showed considerable variance in angle difference for each evaluation tool. Conclusion: According to the results of this study, considering the angle difference between the flexion angle reference points of the evaluation tool and the reference points selected by the observers, it is concluded that instead of personally preferred reference points, the standardized reference points to enhance the accuracy and the objectivity. Application: The result of this study can be used as reference guide to develop the standardized reference point in the future.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.117-126
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• 2018

The purpose of this study was to examine the relationship between the working posture and symptoms of musculoskeletal disorders of dental hygienists during scaling. The subjects in this study were 264 selected dental hygienists. A convergence study was implemented using questionnaire that was prepared to cover general characteristics, health care, the work of scaling, working posture and subjective musculoskeletal symptoms. As for data analysis, R 2.15.1 was employed. As a result of analyzing the collected data, the rate of good working posture during scaling stood at 29.9 percent; roughly good posture, at 37.5 percent; incorrect posture, at 32.6 percent. Regarding the area of the body in which they complained of musculoskeletal symptoms, the shoulders were 3.32-fold more mentioned than any other area(OR,3.32;95%CI, 1.58~6.98); the foot, 2.97-fold more(OR,2.97;95%CI, 1.18~7.48); the hands, 2.84-fold more(OR,2.84:95%CI, 1.35~5.98); the neck, 2.82-fold more(OR, 2.82;95%CI, 1.35~5.91); the back, 2.41-fold more(OR,2.41;95%CI, 1.02~5.68). The findings of the study that demonstrate the importance of good working posture are expected to make a contribution to the improvement of work environments, the development of efficient preventive programs and the preparation of sustained educational plans, and it's necessary in the future to make a research study by including psychosocial factors.

• Journal of Biosystems Engineering
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• v.36 no.3
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• pp.223-230
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• 2011

Physiological signals such as body temperature, heart rate, blood pressure and heart rate variability and biomechanical workload for stress analysis were investigated during the cherry tomato harvesting work in a greenhouse. The skin temperatures raised $0.05^{\circ}C$/min, $0.03^{\circ}C$/ min, and $0.08^{\circ}C$/min in standing, stooping and squatting postures, respectively. Breath rate significantly increased from 18 to 28 breaths/min during the cherry tomato harvesting work. As the heart rate during the work ranged from about 72 to 110 beats/min (bpm), the cherry tomato harvesting work appeared to be a light intensity task of less than 110 bpm. The worker's average energy consumption rate in three positions during 43 min working time was 65.74 kcal (91 kcal/h in 70 kg). This was a light intensity of work, compared to 75 kcal/h in 70 kg of basic metabolic energy consumption rate of a worker with 70 kg weight; The maximum shear force on the disk (L5/ S1) due to static workload in the cherry tomato harvesting work was 446 N in the stooping posture, 321 N in the squatting posture and 287 N in the standing posture. Acute stress index expressed with the heart rate variability, increased parasympathetic activation up to about 70 while workers were doing most agricultural work in this study. This study provided a system to measure quantitatively workers' physiological change, kinematics and kinetic factors without any restrictions of space in the greenhouse works.

• Fashion & Textile Research Journal
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• v.20 no.6
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• pp.704-712
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• 2018

This study analyzed working postures using the Ovako Working Posture Analysis System (OWAS) to improve work clothes for construction workers. A video taken at a construction work site was stopped at regular intervals and the postures of relevant body parts proposed by OWAS was recorded. Additionally, based on analysis of the working postures code, the level of work action for each postures was classified from stage I to IV. General workers frequently straightened or bent forward at the waist, and used their legs to stand, bend, or walk. Wood workers moved extensively from the waist, keeping their legs relatively straight and their arms held below their shoulders, repeatedly tapping with a hammer weighing less than 10.0kg. Rebar bending workers mainly bent forward at the waist, with both legs bent or standing with one leg bent. Rebar transport and fixing workers walked with the waist straight, and occasionally one or both hands held above the shoulders. Their work also involved holding a hook, which weigh less than 10.0kg, in their hands, and the difficult task of lifting and placing long rebars, which weigh from 10.0 to 20.0kg or more. Concrete pouring workers bent or twisted their back to the side. Therefore, this study suggests that design goals should be different when developing workwear for each type of worker.

• Journal of the Korean Society of Safety
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• v.26 no.5
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• pp.81-88
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• 2011

The goal of this study was to determine whether food industry workers are exposed to musculoskeletal loads due to the work time, frequency, awkward postures and inappropriate workspace design. Three catering workers were evaluated based on job analysis and posture analysis. The results showed that the four most time-consuming tasks were arranging(17%), cooking(16%), handling before cooking(15%) and cutting(15%), and the four most frequent tasks were arranging(21%), cooking(18%), handling after cooking(16%) and handling before cooking(13%). The most common posture was a standing posture(73%) with neutral back(73%), and bent head(50%), left lower arm(71%), right lower arm(78%) and right hand(60%). The comparative analysis of subtasks for the risk levels of musculoskeletal disorders was conducted using the work time, frequency and cumulative time of the postures. The 'displaying' and 'handling after cooking' showed higher risk levels than other subtasks. In addition, the height and length of the tables were evaluated to be inadequate for the workers. It can be concluded that the working environments for catering workers of restaurants should be improved due to the high cumulative time of awkward postures of upper extremities.

• The Journal of Korean Physical Therapy
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• v.3 no.1
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• pp.123-149
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• 1991

This study has been attempted to be helpful for the back rehabilization of Korean workers by analyzing the general, occupational, social aspects of low back pain and to identify possible risk factors for back pain in White and Blue collar workers. The primary data were collected from 380 workers in Seoul city by means of a Questionnaire with random which was distributed from March 10 to 31, 1990. For the test of statistical significance, chi-square analysis was used to compare the back pain characteristics between above two groups. The results were as follows : 1. The incidence of low back pain in all walkers studied was $79.7\%$. The incidence of Blue collar with low back pain $(87.2\%)$ was higher than that of White collars $(75.0\%)$. 2. With regard to the relationship of back pain to the occupational characteristics, statistically significant differences were observed between workers with and without back pain concerning the job factors on work-time, job satisfaction, mental stress, chair fittness, work posture, work rotation, weight lifting, monotonous repetitive movements, vibration, and heavy noise (p<0.05). 3. With regard to the relationship of back pain to the social characteristics, there were no differences with respect to having car, personality types, drinking habits, and leisure-time activities. However, significant differences were showed between no pain and pain groups for the using bed, sleeping posture, traffic time amount, walking health state, smoking habits, and physical exercise (p<0.05). 4. The comparative analysis of back pain related to work factors showed highly significant differences with respect to mental stress, chair fittness, work posture, trunk rotation, weight lifting, monotonous repetitive work in White collar group (p<0.01) ; and job satisfaction, mental stress, trunk rotation, weight lifting, monotonus repetitive work, exposure to vibration and heavy noise in Blue collar group(p<0.01). 5. The comparative analysis of social factors in two groups showed differences with respect to the using bed, sleeping posture, walking amount, health state, physical exercise, smoking habits in White cellar group (p<0.05) ; and walking amount, traffic time amount, health state, smoking habits, physical exercise in Blue cellar group (p<0.05). 6. In regard to the general aspects of back pain between two groups, there were differences concerning etiolgy of back pain, counselling partners, treatment types, and sick-leaves(p<0.05), except pain duration, and awareness of back pain.