• Journal of Preventive Medicine and Public Health
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• v.38 no.1
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• pp.71-81
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• 2005

Objective : To elucidate the correlates of self-rated fatigue in Korean employees. Methods : The data for 10,176 (men, 7,984; women, 2,192; mean age, 34.2; SD: 8.8) employees recruited from a nationwide sample were examined. A structured questionnaire was used to measure the participants' fatigue, sociodemographics (sex, age, education, and marital status), job-related characteristics (work duration, grade at work, work hours, shiftwork, employment type, and magnitude of workplace), and health-related habits (smoking, drinking, coffee intake, and exercise). Two types of measurement for fatigue were used to evaluate the magnitude of fatigue: self-rated question and a standardized measurement tool (Multidimensional Fatigue Scale: MFS). Results : According to the self-rated fatigue, 32% of employees reported that they felt fatigue for the past two weeks, and 9.6% of males and 8.7% of females had experienced excessive fatigue (6 months or more). Hierarchical multiple regression analysis showed that fatigue measured by MFS was more common in women, younger, college or more graduated, single, and employees who do not regularly exercise. Fatigue was also associated with long work hours, and the size of the workplace (<1,000 employees). Conclusions : These results suggest that fatigue has been considered as a common complaint, and that it is affected by job-related factors like work hours and the workplace size as well as sociodemographics or health-related behaviors. Further research is needed to clarify the effects of fatigue on adverse health outcomes, work performance, work disability, sick absence and medical utilization, and to examine the relationship of job characteristics (e.g.: work demand, decision latitude) to fatigue.

• Annals of Occupational and Environmental Medicine
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• v.35
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• pp.32.1-32.10
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• 2023

Background: Although many studies have been conducted on worker fatigue and sickness absence, the association between fatigue and sickness absence is unclear in Korean workers. This study was conducted to investigate the effect of worker fatigue on future sickness absence. Methods: The study was conducted on workers who received medical check-ups at a university hospital for two consecutive years (2014-2015). During check-ups in the first year, the Fatigue Severity Scale (FSS) was used to assess fatigue levels, and during check-ups in the second year, sickness absence was surveyed to determine whether they had been absent from work due to physical or mental illness during previous 12 months. The χ² test was used to analyze relationships between sociodemographic and occupational characteristics, fatigue levels, and sickness absence. Odds ratios (ORs) were calculated by logistic regression analysis controlled for confounding factors. Results: A total of 12,250 workers were included in the study, and 396 (3.2%) workers experienced more than one day of sickness absence during the study period. Adjusted ORs for sickness absence were 3.35 (95% confidence interval [CI]: 2.64-4.28) in the moderate-fatigue group and 6.87 (95% CI: 4.93-9.57) in the high-fatigue group versus the low-fatigue group. For men in the moderate- and high-fatigue groups, adjusted ORs for sickness absence were 3.40 (95% CI: 2.58-4.48) and 8.94 (95% CI: 6.12-13.07), and for women in the moderate- and high-fatigue groups, adjusted ORs for sickness absence were 2.93 (95% CI: 1.68-5.10) and 3.71 (95% CI: 1.84-7.49), respectively. Conclusions: Worker fatigue is associated with sickness absence during the following 12 months, and this association appears to be stronger for men than women. These results support the notion that sickness absence can be reduced by evaluating and managing work-related fatigue.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.111.1-111.1
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• 2005

• Journal of Korean Society of Steel Construction
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• v.29 no.3
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• pp.193-204
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• 2017

Fatigue strength of temporary steels and painted structural steels corroded under outdoor atmospheric environments is not clear. In this study, fatigue tests were carried out on steel plates which were cut off from 7-year-old temporary structural member under subway construction environment and from 75-year-old Yeongdo bridge member under marine atmospheric environment. After removing corrosion production on the steel surface, 3-dimensional surface geometry of the corroded steel was measured at intervals of $1.0{\times}1.0mm$, and corrosion characteristics such as minimum, maximum and mean values of residual thicknesses were calculated. From the fatigue test and FEM analysis results, the relationship between corrosion characteristics and fatigue behavior was presented, and change in fatigue strength of the unpainted and painted steels corroded in outdoor environments was also presented.

• Smart Structures and Systems
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• v.14 no.3
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• pp.469-477
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• 2014

As a kind of intelligent materials, conductive asphalt concrete has a broad application prospect including melting ice and snow on the pavement, closing cracks in asphalt concrete, sensing pavement damage, and so on. Conductive pavement will be suffered from fatigue failure as conventional pavement in the process of service, and this fatigue damage of internal structure can be induced by electrical signal output. The characteristics of electrical signal variation of conductive asphalt concrete in the process of fatigue cracking were researched in this paper. The whole process was clearly divided into three stages according to resistance changes, and the development of fatigue damage wasn't obvious in stage I and stage II, while in stage III, the synchronicity between the resistance and damage began to appear. Thus, fatigue damage variable D and initial damage value $D_0$ represented by the functions of resistance were introduced in stage III. After calculating the initial damage value $D_0$ under different stress levels, it was concluded that the initial damage value $D_0$ had no noticeable change, just ranged between 0.24 and 0.25. This value represented a critical point which could be used to inform the repair time of early fatigue damage in the conductive asphalt pavement.

• Women's Health Nursing
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• v.6 no.3
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• pp.427-438
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• 2000

The purpose of this study was to collect basic data the health care of postpartum women. Three hundred seventy five women who were 3 days postpartum were enrolled at two university hospitals. Data were collected from April 1999 to November, 1999 using a questionnaire titled 'Symptom Table on Fatigue Perception' designed by the Fatigue Research Committee of Japan. The collected data were scored by the use of mean and standard deviation according to the subjective symptoms of fatigue and each item was analyzed independent variable by the t-test and the ANOVA test. The results were as follows: 1. The average fatigue score of subjects was 1.61. Physical fatigue had the highest value with a mean of 1.82, followed by neuro-sensory fatigue with a mean score of 1.54, psychological fatigue was rated lowest with a mean of 1.45. 2. With the respect to the general characteristics of subjects, there were statistically significant differences in difficulty of labor (t=2.335. p=.020), sleeping time (t=2.340. p=.020) and desirability of pregnancy (t=2.409. p=.018).

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.18 no.2
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• pp.62-69
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• 2005

Objective: This study is to explore the various aspects of the fatigue perceived by patients with Bell's palsy Method: 33 patients who were diagnosed as Bell's palsy were sequentially interviewed and examined Results: The results were as follows 1. The mean average fatigue score of subjects was $1.79{\pm}0.41$ : the physical fatigue revealed the highest value with a mean of $1.84{\pm}0.50$, followed by neurosensory fatigue with a mean of $1.77{\pm}0.42$, psychological fatigue with a mean score of $1.76{\pm}0.54$. 2. With the respect to the general characteristics of subjects, there were statistically significant differences in the patients' fatigue perception by age and the amount of sleeping time. Conclusions: We needed the further study about the relation between fatigue and Bell's palsy

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.1
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• pp.45-50
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• 1997

It is not clearly known how surface defects or inclusions of a medium carbon steel affect a fatigue strength. In this study, we used SM35C specimens with spheroidized cementite structure to eliminate dependence of micro structure of fatigue crack. The investigation was carried out by behavior of crack closure at non-propagation crack and effect of the fatigue limit according to the artificial defects size. Experimental findings are obtained as follows : (1) Fatigue crack initiation point of medium carbon steel with spheroidized cementite structure is at the surface defects. (2) Non-propagating crack length of smooth specimen is equal to the critical size of defect. (3) Considering the opening and closure behavior of fatigue crack, the defect shape results in various crack opening displacement, while it does not affects the fatigue limit level of medium carbon steel with spheroidized cementite structure. (4) The critical length of the non-propagation crack of smooth specimen is the same as critical size of defect in transient area which determines threshold condition in steel with spheroidized cementite structure.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.136-142
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• 2004

Effects of Nb(Niobium) contents and solution annealing on the strength and fatigue lift of 18%Ni maraging steel commonly using in aircraft, space field, nuclear energy, and vehicle etc. were investigated. Also the fatigue life stress intensity factor were compared experiment result and FEA(finite element analysis) result. The more Nb content, the higher or the lower fatigue lift on base metal specimens or solution annealed specimens showing that the fatigue life was almost the same. The maximum stresses of X, Y, and Z axis direction showed about 2.12${\times}$10$^2$MPa, 4.40${\times}$10$^2$MPa and 1.32${\times}$10$^2$MPa respectively. The Y direction stress showed the highest because of the same direction as the loading direction. The fatigue lives showed about 7% lower FEA result than experiment result showing almost invariable error every analyzed cycle. Stress intensity factor of the FEA result was lower about 3.5∼10% than that of the experiment result showing that the longer fatigue crack length, the higher error. It considered that the cause for the difference was the modeled crack tip having always the same shape and condition regardless of the crack growth.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.149-155
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• 2005

The rotating components such as turbine rotors in service are generally subjected to multiaxial cyclic loading conditions. The prediction of fatigue lift for turbine rotor components under complex multiaxial loading conditions is very important to prevent the fatigue failures in service. In this paper, axial and torsional low cycle fatigue tests were preformed for 3.5NiCrMo steels serviced low pressure turbine rotor of nuclear power plant. Several methods to predict biaxial fatigue life such as Tresca, von Mises and Brown & Miller's critical plane approach were evaluated to correlate the experimental results for serviced NiCrMoV steel. The fracture mode and fatigue characteristics of NiCrMoV steel were discussed based on the results of fatigue tests performed under the axial and torsional test conditions. In particular, the Brown and Miller's critical plane approach was found to best correlate the experimental data with predictions being within a factor of 2.