• Journal of Korean Academy of Nursing
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• v.46 no.4
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• pp.523-533
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• 2016

Purpose: This study was done to examine physical, psycho-social, and individual factors influencing musculoskeletal symptoms among Korean military trainees. Methods: Using a correlation study design, military trainees who had completed almost of all the basic combat training (BCT) days were recruited from two military training units selected by convenience sampling. Data from 415 participants were analyzed. Results: Prevalence of musculoskeletal symptoms was 29.6% defined as a participant having pain or discomfort in one or more body parts during training hours for more than seven consecutive days. Back/pelvic (10.8%), knees (10.1%), shoulders (7.7%), feet/toes (5.6%), ankles (4.8%) were prone to musculoskeletal symptoms. Musculoskeletal symptoms appeared to be related to physical exertion during BCT, stress during BCT, social support from fellow trainees, or previous musculoskeletal injuries. In the logistic regression model, physical exertion during BCT (OR=2.27, 95% CI: 1.42~3.65), stress during BCT (OR=1.79, 95% CI: 1.15~2.78), and previous musculoskeletal injuries (OR=1.58, 95% CI: 1.01~2.47) were the significant factors affecting prevalence of musculoskeletal symptoms. Conclusion: Findings indicate that physical exertion and psycho-social stress should be managed to prevent musculoskeletal symptoms in military trainees with more attention being given to trainees having a history of musculoskeletal injuries.

• Safety and Health at Work
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• v.7 no.3
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• pp.237-243
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• 2016

Background: This study examined the relationship between interhandle distances and upper limb exertion during simply pushing and pulling of a cart with four swivel wheels, defined by a roll box pallet (RBP) in a Japanese industrial standard. Methods: Six healthy young male participants were asked to push and pull an RBP at a distance of 5.2 m under six conditions corresponding to different interhandle distances (40 cm, 60 cm, and 80 cm) and weights (130 kg and 250 kg). The upper limb exertion was studied by shoulder abduction and flexion, and elbow flexion, as well as surface electromyogram (EMG) in shoulder extensor, and elbow flexor and extensor. Participants were required to provide subjective evaluations on operability after each trial. Results: Subjective operability indicated that a narrower interhandle distance had a better operability for pushing. Interhandle distance was also related to upper limb exertion especially for pushing. A narrow interhandle distance caused smaller shoulder adduction but larger elbow flexion. The normalized EMG data revealed that muscular activity became smaller with a narrow interhandle distance in shoulder extensor. During the pulling task, elbow flexion was smaller at a narrow interhandle distance, although subjective operability and normalized EMG were not significantly varied. Conclusion: A wider interhandle distance, such as 80 cm, was not suitable in the forwardbackward movement of the RBP. Therefore, this study concluded that an interhandle distance of 40 cm would be suitable for pushing and pulling an RBP to protect the workers' hands against the risk of injury by installing inner handles.

• Safety and Health at Work
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• v.9 no.2
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• pp.144-148
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• 2018

Background: The objective of this study is to find temporal trends in the associations between cardiovascular disease and occupational risk factors in the context of the Canadian population. Methods: Population data were analyzed from the Canadian Community Health Survey (CCHS) collected between 2001 and 2014 for trends over time between heart disease and various occupational risk factors: hours worked, physical exertion at work, and occupation type (management/arts/education, business/finance, sales/services, trades/transportations, and primary industry/processing). Results: We found no significant difference in the average number of hours worked/wk between individuals who report having heart disease in all years of data except in 2011 ($F_{1,96}=7.02$, p = 0.009) and 2012 ($F_{1,96}=8.86$, p = 0.004). We also found a significant difference in the degree of physical exertion at work in 2001 ($F_{1,79}=7.45$, p = 0.008). There were statistically significant results of occupation type on self-reported heart disease from 2003 to 2014. Conclusion: Canadian data from the CCHS do not exhibit a trend toward an association between heart disease and the number of hours worked/wk. There is an association between heart disease and physical exertion at work, but the trend is inconsistent. The data indicate a trend toward an association between heart disease and occupation type, but further analysis is required to determine which occupation type may be associated with heart disease.

• The Journal of Internal Korean Medicine
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• v.41 no.3
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• pp.293-305
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• 2020

Purpose: This study aimed to develop a questionnaire for the diagnosis of chronic fatigue syndrome (CFS) designed based on the systematic exertion intolerance disorder (SEID) criteria, and to validate the reliability of the questionnaire. Methods: A literature search on questionnaires for CFS diagnosis was conducted to develop a SEID questionnaire (SEID-Q27), followed by a pilot survey to identify the reliability of the questionnaire. Adults (Daejeon university personnel) with a Chalder fatigue scale (CFQ) score ≥15 were invited for the survey. We commenced the survey in November 2019 with a two weeks of interval for the test and retest method. The reliability of the questionnaire was investigated in three angles: 1. Cronbach's α, 2. correlations (r) of the questions, numerical rating scale (NRS), and visual analog scale (VAS), and 3. kappa (k) analysis. Results: Among the total 275 adults registered, 55 (20%) participants with a CFQ score ≥15 were invited, and 31 (11%) [15 male, 16 female] completed the questionnaire. The total Cronbach's α was 0.944 for the test and 0.949 for the retest. The reliability (r) of questions by CFQ score (≥15, ≥18, ≥20) ranged from 0.533-0.928 (p <0.05), and the r score of the NRS and VAS were the highest in CFQ scores ≥20, at 0.933 (p<0.001). The agreement rate of the SEID-Q27 between the test and retest was 87% (kappa k=0.743). Conclusions: The SEID-Q27 seems to be reliable. Further studies are needed to measure the validity of the tool and the cutoff point.

• The Journal of Internal Korean Medicine
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• v.41 no.6
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• pp.1015-1029
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• 2020

Purpose: This study assessed the validity of a questionnaire (SEID-Q27) for diagnosis of chronic fatigue syndrome (CFS), designed based on the systematic exertion intolerance disorder (SEID) criteria. Methods: Two groups of participants were recruited: 1. a non-CFS control group: adult university personnel with a Chalder fatigue scale (CFQ) score ≥15, and 2. a CFS patient group: patients from an online CFS community diagnosed with CFS (diagnostic code of G93.3) with the symptoms present. The survey ran from September to October, 2020. The validity of the questionnaire was investigated by factor analysis and receiver operator characteristic (ROC) analysis. Results: Among the 35 adults surveyed, 30 (86%) participants had CFQ scores ≥15 (15 males and 15 females) and 5 (14%) had a CFS diagnosis (2 males and 3 females). The total mean score was significantly different between the two groups (CFS: 6.8±2.2 vs. control: 4.4±2.4, p<0.05). The area under the curve (AUC) was 0.827. With a cut-off point 62, the sensitivity was 60%, specificity 97%, and the discriminant ability of the survey was 79%. Conclusions: The SEID -Q27 appears to be a useful instrument for the diagnosis of CFS using SEID criteria. However, further large-scale studies are needed with greater numbers of participants.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.2
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• pp.261-278
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• 1998

The paper represented the lower extremity muscle model as four rigid-body segments: trunk, shank, and foot. We transformed their tibial data into our shank data by rotating their tibial X and Y axes by 5.483 degrees, so the revised coordinate data used to translating the origin of their tibial reference frame to our shank reference frame. According to weight of subject, physiological cross-setional area(PCSA) of each lower extremity muscle was calculated by scaling those data by Brand. The objectives of this paper are to investigate the variations of the recruitment patterns of the lower extremity muscles, and to analyze the changes of the role assigned to each muscle during the seated foot operation. For exertion levels, the transition point of type F motor unit of each muscle is inferred by analyzing the electromyogram at the seated postures. Also, for predetermined seated foot operations exertion levels, the recruitment pattern and the changes of the role assigned are identified in the continuous exertion, by analyzing the electromyogram changes due to the accumulated muscle fatigue. This study can be used to design and to assess the pedals and foot-related equipments design.

• Journal of the Ergonomics Society of Korea
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• v.32 no.6
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• pp.541-547
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• 2013

Objective: The aim of this study is to find the influence on muscle fatigue by changing an angle of neck while Shaker exercise. Background: Shaker exercise is commonly applied to dysphagia patients for strengthen suprahyoid muscle(SHM) and relaxing upper esophageal sphincter. Method: Experiments were conducted by measuring muscle fatigue with surface electromyography(SEMG) in case of neck $15^{\circ}$ and $50^{\circ}$ flexion, in addition to original method. For the study 30 undergraduate students were participated as subjects. Muscle fatigue was measured with variations of median frequency(MF) and median frequency slope(MFS) by attaching SEMG to 3 muscles. At the same time, perceived exertion was measured by using Borg's rating of perceived exertion(RPE). Results: A MF was increased when low angle in SHM, both male and female. It means that muscle fatigue was significantly decreased(p<.05). RPE was significantly increased when low angle(p<.01). Perceived exertion explained 15.2% of the variation of MF in SHM. And regression equation was, MF in SHM = 59.918 + (4,910 * RPE). Conclusion: The outcome shows that it is possible to use the efficient method which makes muscle fatigue decrease by reducing the angle of neck flexion. Application: The results might contribute to develop the effective Shaker exercise method.

• Proceedings of the ESK Conference
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• 1994.04a
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• pp.115-123
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• 1994

A man model can be used as an effective tool to design ergomonically sound products and workplaces, and subsequently evaluate them properly. For a man model to be truly useful, it must be integrated with a posture prediction model which should be capable of representing the human arm reach posture in the context of equipments and workspaces. Since the human movement possesses redundant degrees of freedom, accurate representation or prediction of human movemtn was known to be a difficult problem. To solve this redundancy problem, the psychophysical cost function can predict the arm reach posture accurately. But the joint discomfort that human feels at the joint can not be predicted since the effects of external factors on the joint discomfort is not known. In this study a psychophysical experi- ment using the magnitude estimation technique was performed to evaluate the effects of external factors such as joint, joint angle and Perceived Exertion Ratio on the joint discomfort. Results showed that the joint discomfort increased as the Perceived Exertion Ratio increased, but the relation is not linear and was affected not only by the joint but also by the joint angle for the same Perceived Exertion Ratio. The interaction effect of the joint and the joint angle was also significant. From the results it is needed to develope the cost function which can predict the joint discomfort considering the joint, joint angle and external load.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.60
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• pp.37-46
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• 2000

A biomechanical model of lower extremity in seated postures was developed to assess muscular activities of lower extremity involved in a variety of foot pedal operations. The model incorporated four rigid body segments with the twenty-four muscles to represent lower extremity This study deals with quasi-static movement to investigate dynamic movement effect in seated foot operation. It is found that optimization method which has been used for modeling the articulated body segments does not predict the forces generated from biarticular muscles and antagonistic muscles reasonably. So, the revised nonlinear optimization scheme was employed to consider the synergistic effects of biarticular muscles and the antagonistic muscle effects from the stabilization of the joint. For the model validation, three male subjects performed the experiments in which EMG activities of the nine lower extremity muscles were measured. Predicted muscle forces were compared with the corresponding EMG amplitudes and it showed no statistical difference. For the selection of optimal seated posture, a physiological meaningful criterion was developed for muscular load sharing developed. For exertion levels, the transition point of type F motor unit of each muscle is inferred by analyzing the electromyogram at the seated postures. Also, for predetermined seated foot operations exertion levels, the recruitment pattern is identified in the continuous exertion, by analyzing the electromyogram changes due to the accumulated muscle fatigue.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.56
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• pp.45-53
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• 2000

A laboratory experiment was conducted to investigate the effects of body posture and of different types of common non-powered hand tools on maximum volitional torque exertion capabilities of Korean. Fifteen males and 15 females were participated in the experiment. Each subject exerted maximum volitional torque in 15 different body postures while using five different common non-powered hand tools. Results of the data analysis showed that, for both males and females, the magnitude of torque exertion is significantly affected by the type of tool and posture. Also the result indicated that females exerted only about 51.5% of torque when compared to that of males. This result is different with the general findings in the field of ergonomics that the muscular strength of female is usually 65% to 75% of male. It suggests that application of same profile of muscular strength of female as in the western population should be carefully considered in oriental countries since females in this region may possess less physical capability compare to that of western females in terms of percentage muscular strength of males. Profiles of maximum torque capabilities of Koreans are provided.