• Journal of the Ergonomics Society of Korea
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• v.26 no.2
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• pp.157-165
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• 2007

The Work-Related Musculoskeletal Disorders (WMSDs) can be occurred by various factors such as repetition, forceful exertions and awkward postures. Especially, occurrences of the WMSDs on the waist and lower limb are reported in workplaces, demanded standing postures for a long time, in service and manufacturing industry. The static and standing postures without movement for a long time increase work loads to the lower limb and the waist. Accordingly, anti-fatigue mat or anti-fatigue insole is used as a preventing device of the WMSDs. However anti-fatigue mats are limited in space and movement. In this study, multi-elastic insoles are designed and shown the effects of the workload reduction for a long time under the standing work. The foot pressures and EMG (Electromyography) are measured at 0 hour and after 2 hours by 6 health students in their twenties. The 6 prototype insoles are designed with three elastic (Low, Medium and High). These insoles are compared with no insole (insole type 7) as control group. The EMG measurement was conducted to waist (erector spinae muscle), thigh (vastus lateralis muscle) and calf (gastrocnemius muscle). The foot pressure is analyzed by mean pressure value and the EMG analysis is investigated through MF (Median Frequency), MPF (Mean Power Frequency) and ZCR (Zero Crossing Rate). The results of the foot pressure show that the multi-elastic insoles had smaller foot pressure value than that of no-insole. Moreover, Insole 2 and Insole 3 have the smallest increasing rate in foot pressure. The EMG results show that the multi-elastic insoles had smaller EMG shift value than that of no-insole in 2 hour, and then shift value shows the smallest value in Insole 2. Therefore, this study presents that the multi-elastic insoles have reducing effects of the work load for a long time standing work in both side of foot pressure and EMG.

• Physical Therapy Korea
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• v.28 no.3
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• pp.215-226
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• 2021

Background: Robot-assisted gait training (RAGT) is an effective method for walking rehabilitation. Additionally, the body weight support (BWS) system reduces muscle fatigue while walking. However, no previous studies have investigated the effects of RAGT with BWS on isokinetic strength of quadriceps and hamstring muscles. Objects: The purpose of this study was to investigate the effects of torque, work, and power on the quadriceps and hamstring muscles during RAGT, using the BWS of three conditions in healthy subjects. The three different BWS conditions were BWS 50%, BWS 20%, and full weight bearing (FWB). Methods: Eleven healthy subjects (7 males and 4 females) participated in this study. The Walkbot_S was used to cause fatigue of the quadriceps and hamstring muscles and the Biodex Systems 4 Pro was used to measure the isokinetic torque, work, and power of them. After RAGT trials of each of the three conditions, the subjects performed isokinetic concentric knee flexion and extension, five at an angular velocity of 60°/s and fifteen at an angular velocity of 180°/s. One-way repeated analysis of variance was used to determine significant differences in all the variables. The least significant difference test was used for post-hoc analysis. Results: On both sides, there were significant differences in peak torque (PT) of knee extension and flexion between the three BWS conditions at an angular velocity of 60°/s and 180°/s conditions. A post-hoc comparison revealed that the PT in the BWS 50% was significantly greater than in the BWS 20% and the FWB and the PT in the BWS 20% was significantly greater than in the FWB. Conclusion: The results of this study suggest that the lower BWS during RAGT seems to lower the isokinetic torque, work, and power of the quadriceps and hamstring muscles because of the muscle fatigue increase.

• Steel and Composite Structures
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• v.22 no.2
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• pp.353-368
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• 2016

This paper extends our recent work on the fatigue behavior of stud shear connectors in steel and recycled tyre rubber-filled concrete (RRFC) composite beams. A series of 16 fatigue push-out tests were conducted using a hydraulic servo testing machine. Three different recycled tyre rubber contents of concrete, 0%, 5% and 10%, were adopted as main variable parameters. Stress amplitudes and the diameters of studs were also taken into consideration in the tests. The results show that the fatigue lives of studs in 5% and 10% RRFC were 1.6 and 2.0 times greater of those in normal concrete, respectively. At the same time, the ultimate residual slips' values of stud increased in RRFC to highlight its better ductility. The average ultimate residual slip value of the studs was found to be equal to a quarter of studs' diameter. It had also been proved that stress amplitude was inversely proportional to the fatigue life of studs. Moreover, the fatigue lives of studs with large diameter were slightly shorter than those of smaller ones and using larger ones had the risk of tearing off the base metal. Finally, the comparison between test results and three national codes was discussed.

• Korean Journal of Occupational Health Nursing
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• v.20 no.3
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• pp.261-269
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• 2011

Purpose: The purpose of this study was to investigate occupational stress and fatigue level of neonatal nurses and to assess relationship between the two of them. Methods: Subjects were 109 neonatal nurses working at 2 university hospitals and 9 women's hospitals in D city, and the data were analyzed using descriptive statistics and binary logistic regression analysis by the SPSS/WIN 15.0. Results: The mean score of nurses' occupational stress level was 3.22, and the highest was 'night shift' among the 7 subcategories, and fatigue level was 62.0, and the highest was physical fatigue in configuration field. In logistic regression analyses, 'heavy workload' and 'inadequate physical environment' led to most occupational stress. Conclusion: In addition to significantly higher levels of occupational stress of neonatal nurses, the cumulative fatigue also resulted in decreased quality of nursing, job satisfaction and nursing productivity; therefore, appropriate number of nurses and improvement of work environment is necessary. Furthermore, to reduce the occupational stress and fatigue, we should try to develop adequate clinical guidelines and intervention strategies and apply them in neonatal care unit.

• Steel and Composite Structures
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• v.25 no.1
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• pp.57-65
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• 2017

The fatigue fracture of studs is the main reason for failure of composite beams based on massive engineering practices. Hence, studying the laws of cracks initiation and propagation are of great directive significance. eXtended Finite Element Method (XFEM) is an effective method in solving moving discontinuous problems in recent years. This paper extends our recent work on the fatigue damage analysis of stud shear connectors in the steel and crumble rubber concrete (RRFC) composite beams based on XFEM. The process of crack initiation to failure of the stud is simulated and an effective calculation criteria for the fatigue life of the composite beams is put forward. After the reliability of the numerical analysis is verified based on tests results, the extensive parametric study is conducted concerning effects of different rubber contents, shear connection degrees and the stress amplitudes. Results show that with the increasing rubber contents and shear connection degrees, the fatigue lives of composite beams increase obviously. Furthermore, the relationship between the fatigue life of the stud at the edge of the shear span and the whole composite beams is studied. Finally, the S-N curves of the single stud and the whole composite beams are put forward based on XFEM.

• Journal of the Korea Safety Management & Science
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• v.14 no.4
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• pp.51-58
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• 2012

This study attempted to evaluate the direct and indirect effect of emotional labor, job and psychosocial stress, and fatigue of beauty industry workers on their musculoskeletal diseases. The findings of this study showed that, among the workers with perceived symptoms of musculoskeletal diseases, the body part with the most commonly occurring symptom was the shoulder, followed by neck, low back, wrist, arm, foot and knee. As for the effect of work-related psychological factors on musculoskeletal diseases, it was found that the workers with musculoskeletal diseases were more affected by emotional labor and fatigue than non-symptom workers. It was also shown that when their job stress increased, the fatigue level also increased, though their psychosocial stress decreased. In addition, it was found that both direct and indirect effects of emotional labor on fatigue were high, and the indirect effect of job stress through fatigue on musculoskeletal diseases was significant.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.3
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• pp.241-249
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• 2003

The service life of steel bridges can be assured only when their strength, serviceability and fatigue safety are fulfilled. However, at the present time, the continuous research for fatigue of steel bridges is desperately required since not much research work has been done so far. In this study, a guideline on the fatigue design is suggested for the practical purpose in order to establish the long-term safety of steel bridges against fatigue. The continuous steel truss bridge was analyzed for the cumulative reversals of the actual traffic, stress ranges and fatigue strength. From the results, the domestic fatigue design procedure was found to be fairly overestimated in comparison to the design code of other foreign countries. Therefore, it is necessary to review the current fatigue design specifications and have the new and rationalized design criteria in the future domestic fatigue design guidance.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.741-747
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• 2022

Fatigue lowers an individual's ability and makes it difficult to perform work. As fatigue accumulates, concentration decreases and thus the possibility of causing a safety accident increases. Awareness of fatigue is subjective, but it is necessary to quantitatively measure the level of fatigue in the actual field. In previous studies, it was proposed to measure the level of fatigue by expert judgment by adding objective indicators such as bio-signal analysis to subjective evaluations such as multidisciplinary fatigue scales. However this method is difficult to evaluate fatigue in real time in daily life. This paper is a study on the fatigue classification model that determines the fatigue level of workers in real time using speech data recorded in the field. Machine learning models such as logistic classification, support vector machine, and random forest are trained using speech data collected in the field. The performance evaluation showed good performance with accuracy of 0.677 to 0.758, of which logistic classification showed the best performance. From the experimental results, it can be seen that it is possible to classify the fatigue level using speech signals.

• Safety and Health at Work
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• v.5 no.4
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• pp.216-221
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• 2014

Background: Mental health complaints are quite common in health care employees and can have adverse effects on work functioning. The aim of this study was to evaluate an e-mental health (EMH) approach to workers' health surveillance (WHS) for nurses and allied health professionals. Using the waiting-list group of a previous randomized controlled trial with high dropout and low compliance to the intervention, we studied the pre- and posteffects of the EMH approach in a larger group of participants. Methods: We applied a pretest-posttest study design. The WHS consisted of online screening on impaired work functioning and mental health followed by online automatically generated personalized feedback, online tailored advice, and access to self-help EMH interventions. The effects on work functioning, stress, and work-related fatigue after 3 months were analyzed using paired t tests and effect sizes. Results: One hundred and twenty-eight nurses and allied health professionals participated at pretest as well as posttest. Significant improvements were found on work functioning (p = 0.01) and work-related fatigue (p < 0.01). Work functioning had relevantly improved in 30% of participants. A small meaningful effect on stress was found (Cohen d = .23) in the participants who had logged onto an EMH intervention (20%, n = 26). Conclusion: The EMH approach to WHS improves the work functioning and mental health of nurses and allied health professionals. However, because we found small effects and participation in the offered EMH interventions was low, there is ample room for improvement.

• Korean Journal of Social Welfare
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• v.69 no.2
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• pp.271-294
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• 2017

Social workers empathized with clients'distress, feel concerned for clients in distress, and try to reduce their distress. This is called compassion. Compassion is an essential component of social work practice. However, compassion results in both positive results and negative results. The purpose of this study is to evaluate the Korean version of ProQOL which was developed to measure compassion satisfaction and compassion fatigue of helping professionals, to identify levels of compassion satisfaction/fatigue of the participants, and to divide the participants into clusters by clustering variables which are compassion satisfaction/fatigue. A total of 284 social workers residing in Seoul and Surrounding areas participated in this study. Confirmatory factor analysis confirmed that the Korea version of ProQOL is composed of compassion satisfaction factor and compassion fatigue factor as reported in a previous study. Its reliability and validity were satisfactory. The level of participants'compassion satisfaction was above moderate and their level of compassion fatigue was below moderate. Those who are older, have graduate education, have more years of work experience, or have higher positions have more compassion satisfaction. Cluster analysis divided the participants into 3 clusters. Cluster 1 is characterized by moderate compassion satisfaction and low compassion fatigue, Cluster 2 is characterized by low compassion satisfaction and moderate compassion fatigue, and Cluster 3 is characterized by high compassion satisfaction and high compassion fatigue.