• Journal of the Korea Safety Management & Science
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• v.13 no.2
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• pp.83-90
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• 2011

It has been very important to have an exact evaluation for risk factors in order to prevent WMSDs(Work-related Musculoskeletal Disorders). However, most WMSDs evaluation methods have always been some problems of possibilities associated with subjective evaluation. Therefore, this study tried to conduct a sort of usability analysis on three major evaluation methods(OWAS, RULA, REBA). Specifically, major subjects in the study consisted of three parts as follows; comparison of the results between experienced and inexperienced observers, analysis for the consistency of the results in terms of different evaluation times, and analysis for the consistency of the results in terms of different job characteristics(based on the part of the automobile). The results of the study were summarized as follows; 1) There was statistically significant difference of the results by RULA and by REBA between experienced and inexperienced observers. This might be due to the fact that experienced observers have had better ability to detect the important working posture during evaluation. However, the results by OWAS did not give any significantly different results between experienced and inexperienced observers, 2) All three checklists applied by experienced subjects did not show any single result significantly different in terms of different evaluation times. This might have to do with high intra-observer reliability from some of previous studies, 3) The five parts of an automobile were selected as five major jobs with different job characteristics in the automobile industry. Specifically, they were door part, front part(hood, etc.), inside part(dash board, seats, etc.), rear part(trunk etc.), and bottom part. All three methods did not show any significant differences for the results from each observers. Further study on this subject would eventually provide a sophisticated evaluating guidelines for WMSDs regarding determination of observer-specific evaluation, identification of repetitive number of evaluations for stable results for each checklist, determination of job-specific evaluation methods, and so on.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.88-94
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• 2013

The purpose of this study is to find out the difference of foot pressure according to the firefighter's work postures for providing the basic information to prevent Musculoskeletal disorders. This study was conducted by 9 male firefighters. Work postures were selected for rescuee handling, fire hose and hydraulic rescue equipment work postures. These were divided into 3 position, "High", "Middle" and the postures of taking out and letting down hydraulic rescue equipment were analyzed as starting point and end point respectively. Foot Pressure was used to analyze contact area, peak pressure, and maximum force in terms of work postures, and compared between fire hose and hydraulic rescue equipment work postures. The results of foot pressure are as follows. According to the results of rescuee handling work postures, one person handling posture showed wide contact area and foot pressure showed the highest at right foot. Accoridng to the (High), (Middle), (Low) postures of fire hose, the results didn't show the difference among the contact area, peak pressure and maximum force. As the results of hydraulic rescue equipment work postures, (Low) postures showed the highest in terms of the right foot of contact area, peak pressure and maximum force and (High) postures showed the highest in left foot. The increase of foot pressure lead to be inconvenience of low extremity and muscle fatigue for maintaining postural control cause pain. Thus, it is necessary to design insole-equipped working shoe for reduce the impulse and effect of foot during the rescuee handling work which standing out as foot pressure.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.2
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• pp.184-197
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• 2021

The purpose of this study was to investigate the characteristics related to the musculoskeletal disorders in pediatric dentists and general dentists. This study was conducted based on the survey results of a total of 109 dentists who have been working for the last year. Forty - three pediatric dentists and 66 general dentists were surveyed through online survey tool. Both pediatric dentists and general dentists mainly complained of musculoskeletal disorders in the neck, shoulders, wrists, and back. Most pediatric dentists usually suffered from back pain due to their unbalanced posture while giving dental treatments. Pediatric dentists in sedative treatment felt more pain in particular part of their body, such as neck and shoulder. Regular exercise and stretching for the prevention of musculoskeletal disorder have been shown to mainly relieve pain in the back but no other parts in their body.

• Journal of Korean society of Dental Hygiene
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• v.19 no.5
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• pp.665-676
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• 2019

Objectives: The purpose of the study was to analyze the association between indirect vision skills and neck, shoulder, and back pain in dental hygienists. Methods: This cross-sectional study included 85 dental hygienists working full-time at dental clinics. A survey was performed for musculoskeletal symptoms in the neck, shoulders, and back of the subjects. The O'Connor tweezer dexterity test was performed using a mirror to evaluate their indirect vision skills. For statistical analyses, the t-test and one-way analysis of variance were performed. Results: The neck was the most common region of musculoskeletal pain (89.4%). The most intense pain was experienced in the neck (70.6%) and right shoulder (60.0%). Neck pain (20.0%) caused the most interference with clinical practice. Indirect vision skills were lower in the group with severe pain in the left shoulder or with high interference in work due to the left shoulder pain (p=0.026 and p= 0.017, respectively) or right shoulder pain (p=0.004). Conclusions: In this study, neck pain was a major musculoskeletal symptom among dental hygienists, and poor indirect vision skills were associated with the development of shoulder pain. Therefore, to prevent such musculoskeletal symptoms, dental hygienists should become proficient in indirect visualization, which enables a balanced and neutral posture.

• Korean Journal of Applied Biomechanics
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• v.33 no.1
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• pp.1-9
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• 2023

Objective: This study identifies the difference among the heights of a chair's backrest (High, Mid, No), the biomechanical changes chair users undergo over time, and the variables that can measure musculoskeletal disorders, eventually providing information on the appropriate type of backrest. Method: Eleven healthy subjects in their 20s and 30s who had no experience with musculoskeletal disorders or surgical operations within the last 6 months participated in this study. Computer typing tasks were randomly designated and performed according to the type of chair backrest, and evaluation was performed for Flexion-Relaxation Ratio (FRR) analysis after the computer typing tasks. This study used eight infrared cameras (sampling rate: 100 Hz) and nine-channel electromyography (sampling rate: 1,000 Hz). ANOVA with repeated measures was conducted to verify the results, with the statistical significance level being α = .05. Results: Although there was no significant difference in craniovertebral angle (CVA), this study showed time and interaction effects depending on the height of the backrest (p<.05). When working without the backrest, the head-spine angle was lower compared to the chairs with backrest, based on the computer work. As for the head angle, the higher the back of the chair was, the less the head flexion and the body angle became, whereas the body flexion became less when there was a backrest. In addition, the body flexion increased over time in all types of backrests (p<.05). The muscle activity of the upper body tended to be high in the high backrest chair. On the other hand, a lower muscle activity was found with a low backrest. Conclusion: These results show that a chair is more ergonomic when the body angle is correctly set without bending and when it is supported by a low backrest. Accordingly, this study determines that the backrest affects shoulder and neck musculoskeletal disorders during typing and that medium-height backrest chairs can help prevent musculoskeletal disorders, contrary to the expectation that high-backrest chairs are preferable.

• Safety and Health at Work
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• v.14 no.1
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• pp.66-70
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• 2023

Background: Online teaching and learning extend the duration of using gadgets such as mobile phones and tablets. A prolonged usage of these gadgets in a static position can lead to musculoskeletal disorders (MSD). Therefore, this study aims to identify the risk factors related to musculoskeletal symptoms while using gadgets during work from home due to the COVID-19 pandemic. Method: A cross-sectional survey with online-based questionnaires was collected from the University of Indonesia, consisting of lecturers, students, and managerial staff. The minimum number of respondents was 1,080 and was defined by stratified random sampling. Furthermore, the dependent variable was musculoskeletal symptoms, while the independent were age, gender, job position, duration, activity when using gadgets, and how to hold them. Result: Most of the respondents had mobile phones but only 16% had tablets. Furthermore, about 56.7% have used a mobile phone for more than 10 years, while about 89.7% have used a tablet for less than 10 years. A multivariate analysis found factors that were significantly associated with MSD symptoms while using a mobile phone, such as age, gender, web browsing activity, work, or college activities. These activities include doing assignments and holding the phone with two hands with two thumbs actively operating. The factors that were significantly associated with MSD symptoms when using tablets were gender, academic position, social media activity, and placing the tablet on a table with two actively working index fingers. Conclusion: Therefore, from the results of this study it is necessary to have WFH and e-learning policies to reduce MSD symptoms and enhance productivity at work.

• Magazine of the Korean Society of Agricultural Engineers
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• v.21 no.3
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• pp.83-91
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• 1979

This study was conducted in order to find out the performance of rice transplanters in accordance with the change of the trans-planting days after pudding and the water depth flooding the paddy field at the time of transplanting : and thus to select the optimum paddy field preparation procedures for an efficient utilization of rice transplanters. The performance factors of the two different types of rice transplanters were measured during the first 6 consecutive days after puddling and with 3 different levels of water depth flooding the paddy fields. The results of this study were analysed and summarized as follows : 1. Wheel sinkage decreased very rapidly from 0 to 2 days after puddling and slowly from 3 to 5 days after puddling. 2. The depth of the test cone penetration decreased rapidly during the first few days after puddling. It was 17.8cm just after puddling, and decreased to 13.4cm one day after puddling. After 2 days, the rate of decrease was dampened, and after 5 days it kept constant value of 9.2cm. 3. Two days after puddling, the hill interval was 15.8cm (98.75% of the preset value) for broadcasted seedling rice transplanter with 3cm flooding depth : This value was the closest to the pre-adjusted value of 16cm. The general performance of broadcasted-seedling type rice transplanter was better than that of strip-seedling type rice transplanter. 4. Usually the working performance of a rice transplanter is evaluated with uniformity and adjustability of the hill intervals. The hill interval was the most uniform and closest to the pre-set value of 16cm when planted two days after puddling with 3cm of water depth. When it was inavoidable to plant 4 days after puddling with stripseedling type rice transplanter, it is advisable to let the water flooded somewhat deeper. 5. The percentage of missing hills including floating and burried seedlings was the highest just after puddling and ie decreased substancially until 3 days after puddling and then it increased again. Hence, the optimal time transplanting is to be between 2 and 3 days after puddling. 6. Better postures of planted seedlings were found when planter 2 days after puddling than 3 days after puddling. Six cm of flooding water depth always gave the best results with respect to the postures of planted seedlings. Broadcasted-seedling rice transplanter, in general, showed better posture of planted seedlings than did strip-seedling type rice transplanter. 7. Judging from the above results, the optimal conditions will be 3cm of flooding depth and transplanting between 2 and 3 days after puddling.

• Journal of National Security and Military Science
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• s.9
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• pp.313-340
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• 2011

The National Defense Reformation bill of "National Defense Reformation 2020" which have been constantly disputed and reformed by the government went through various levels of complementary measures after the North Korean sinking on the Republic of Korea (ROK) Naval Vessel "Cheonan". The final outcome of this reform is also known as the 307 Plan and this was announced on the 8th March. The reformed National Defense Reformation is to reduce the number of units and military personnel under the military structure reformation. However, in order for us to undertake successful National Defense Reformation, the use of privatized civilian resources are essential. Therefore according to this theory, the ROK Ministry of National Defense (MND) have selected the usage of privatized resources as one of the main core agenda for the National Defense Reformation management procedures, and under this agenda the MND plans to further expand the usage of private Especially the MND plans to minimize the personnel resources applied in non-combat areas and in turn use these supplemented personnel with optimization. In order to do this, the MND have initiated necessary appropriate analysis over the whole national defense section by understanding various projects and acquisition requests required by each militaries and civilian research institutions. However for efficient management of privatized civilian resources, first of all, those possible efficient private resources which can achieve optimization will need to be identified, and secondly continuous systematic reinforcements will need to be made in private resource usage legislations. Furthermore, we would need to consider the possibility of labor disputes because of privatization expansion. Therefore, full legal and systematic complementary measures are required in all possible issue arising areas which can affect the combat readiness posture. There is another problem of huge increase in operational expenses as reduction of standby forces are only reducing the number of soldiers and filling these numbers with more cost expensive commissioned officers. However, to overcome this problem, we would need to reduce the number of positions available for active officers and fill these positions with military reserve personnel who previously had working experiences with the related positions (thereby guaranteeing active officers re-employment after completing active service). This would in tum maintain the standards of combat readiness posture and reduce necessary financial budgets which may newly arise. The area of maintenance, supply, transportation, training & education duties which are highly efficient when using privatized resources, will need to be transformed from military management based to civilian management based system. For maintenance, this can be processed by integrating National Maintenance Support System. In order for us to undertake this procedure, we would need to develop maintenance units which are possible to be privatized and this will in turn reduce the military personnel executing job duties, improve service quality and prevent duplicate investments etc. For supply area, we will need to establish Integrated Military Logistics Center in-connection with national and civilian logistics system. This will in turn reduce the logistics time frame as well as required personnel and equipments. In terms of transportation, we will need to further expand the renting and leasing system. This will need to be executed by integrating the National Defense Transportation Information System which will in turn reduce the required personnel and financial budgets. Finally for training and education, retired military personnel can be employed as training instructors and at the military academy, further expansion in the number of civilian professors can be employed in-connection with National Defense Reformation. In other words, more active privatized civilian resources will need to be managed and used for National Defense Reformation.

• Science of Emotion and Sensibility
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• v.20 no.2
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• pp.103-116
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• 2017

We studied the actual condition of work environment and work morale according to the type of employment of service workers by using the raw data of the Fourth Work Environment Survey (2014) conducted by the Institute of Occupational Safety and Health. In this study, the condition of work environment were composed of work posture, emotional labor, and work autonomy. Also, dimensions related to work morale were composed of competence, job satisfaction, social support, and job stress. In addition, the employment was classified into three types of regular workers, temporary workers, and daily workers. The results showed that temporary and daily workers were more likely to work in a less favorable environment than regular workers, and there was a close correlation between work environment and work morale. Based on this study, it is possible to know about the actual situation and problems of the service workers, and it is hoped that company can search for measures to increase the working environment and work morale of the workers in order to provide better service.

• Korean Journal of Rural Living Science
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• v.8 no.1
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• pp.7-13
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• 1997

In this study we examined the greenhouse worker's work load to test the efficiency of the developed vehicles (hand operated vehicle (HV), simple battery-powered autonomous vehicle (AV)). The subject of this study were healthy adult females who had experience in growing crops. We measured workers' heart rate, blood Pressure. rectal temperature, mean skin temperature, oxygen consumption and blood lactate level as a physiological index of work load. The results of this study are as follows : The test group using experimental vehicle showed the lower heart rate (mean$\pm$S.D. for HV, AV respectively 74$\pm$5, 75$\pm$3 beats/min, p＜0.01) than the control group (84$\pm$8beat/min) not using experimental vehicle and the lower systolic blood Pressure (HV, AV respectively 109$\pm$8, 109$\pm$9 mmHg, p＜0.01) than the control group (121$\pm$11 mmHg), and lower rectal temperature(HV, AV respectively 37.0$\pm$0.1, 36.8$\pm$0.2$^{\circ}C$, p＜0.01) than the control group (37.0$\pm$0.2$^{\circ}C$), and the less oxygen consumption (HV, AV respectively 2.13$\pm$0.09, 1.66$\pm$0.52$m\ell$/kg/min, p＜0.01) than the control group(2.43$\pm$0.12$m\ell$/kg/min), and the lower blood lactate level (HV, AV respectively 2.03$\pm$1.00, 1.66$\pm$0.52mmol, p＜0.01) than the control group (2.43$\pm$0.12mmol). Judging from these results, these experimental vehicles for greenhouse workers can be confirmed as a useful tool. It is suggested that these vehicles would alleviate the peasant's syndrome including muscle fatigue and musculoskeletal disease usually caused by working in an uncomfortable posture.