• Structural Engineering and Mechanics
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• v.35 no.3
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• pp.283-299
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• 2010

This paper addresses the numerical simulation of fatigue crack growth in arbitrary 2D geometries under constant amplitude loading by the using a new finite element software. The purpose of this software is on the determination of 2D crack paths and surfaces as well as on the evaluation of components Lifetimes as a part of the damage tolerant assessment. Throughout the simulation of fatigue crack propagation an automatic adaptive mesh is carried out in the vicinity of the crack front nodes and in the elements which represent the higher stresses distribution. The fatigue crack direction and the corresponding stress-intensity factors are estimated at each small crack increment by employing the displacement extrapolation technique under facilitation of singular crack tip elements. The propagation is modeled by successive linear extensions, which are determined by the stress intensity factors under linear elastic fracture mechanics (LEFM) assumption. The stress intensity factors range history must be recorded along the small crack increments. Upon completion of the stress intensity factors range history recording, fatigue crack propagation life of the examined specimen is predicted. A consistent transfer algorithm and a crack relaxation method are proposed and implemented for this purpose. Verification of the predicted fatigue life is validated with relevant experimental data and numerical results obtained by other researchers. The comparisons show that the program is capable of demonstrating the fatigue life prediction results as well as the fatigue crack path satisfactorily.

• Journal of muscle and joint health
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• v.6 no.1
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• pp.136-152
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• 1999

The purposes of this study were to identify the prevalence of fatigue. and factors influencing fatigue in women with rheumatoid arthritis. The subjects were 124 patients with rheumatoid arthritis. Most of all patients felt fatigue and mean score measured by Multidimensional Assessment of Fatigue was relatirely high. Fatigue was positively correlated with pain intensity, the number of pain sites, functional disability, depression. and sleep quality. A hierachical regression model was used to determine the variance which accounts for fatigue. Pain intensity, depression. sleep quality accounted for fatigue significantly. This finding indicates that pain influences fatigue through depression and sleep quality ; depression through sleep quality. The causative factors could be identified by further study of structural eqation model.

• Child Health Nursing Research
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• v.22 no.4
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• pp.363-369
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• 2016

Purpose: Fatigue in mothers of hospitalized children is an important component for her child's health. This study was done to identify factors influencing fatigue in mothers of hospitalized children. Methods: A descriptive correlation study design was used. Participants were 157 mothers of hospitalized children in a university hospital located in one city. Data were analyzed using t-test, ANOVA, Pearson correlation coefficients and stepwise multiple regression. Results: Mean score for fatigue in mothers of hospitalized children was $2.11{\pm}0.53$. There were significant differences in scores for fatigue in these mothers according to education, sleep satisfaction, and family support. Multiple regression analysis showed that the important factors related to fatigue in mothers of hospitalized children were parenting stress (${\beta}=.44$), hours of sleep (${\beta}=-.25$), and age (${\beta}=-.21$). These factors explained 38% of the total variance. Conclusion: Research results suggest that nursing interventions for mothers of hospitalized children are needed in order to improve the comfort and health of the mothers and facilitate the recovery of their child.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.11 no.2
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• pp.220-225
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• 2004

Purpose: The purpose of this study was to test the reliability and validity of FAI and to apply it in Korea. Method: Data were collected from 180 middle-age women. The questionnaire, which was originally developed by Schwartz, Jandorf & Krupp, was analyzed using Cronbach's a and factor analysis. Results: Cronbach's a for the FAI was .9198. As a result of item analysis, 27 items were selected from the total of 29 items, Items that showed low correlation with the total scale were excluded. Six factors were fixed from the data analysis performed using principle component analysis and varimax rotation. These six factors account for 65.3% of total variance. The first factor was global fatigue severity, and the second one was fatigue consequences. The other factors were method of fatigue reduction, fatigue caused by exercise, fatigue caused by routine activity, and fatigue caused by stress and depression, sequentially. Conclusion: The reliability and validity of FAI were verified.

• Journal of muscle and joint health
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• v.6 no.1
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• pp.73-84
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• 1999

This study was conducted to identify the characteristics of fatigue and its influencing factors in patients having chronic arthritis. The subjects of this study were 120 patients who visited a Rheumatis Center of H University Hospital. Data were collected from Aug. 9, 1997 to Feb. 5, 1998. For analysing data, SPSS/Win was used for descriptive statistics & Pearson's correlation coefficient, and Lisrel 8.0 was for path analysis. The findings were as follows : 1. Mean score of subjective fatigue was 5.36 and it means moderate degree of fatigue. 2. Fatigue showed positive relationship with pain & depression, and it showed negative relationship with ADL & self efficacy. 3. Fatigue was influenced by pain and depression. and was not influenced by ADL and self efficacy directly. But ADL and self efficacy influenced on fatigue through pain and depression indirectly. According to this findings. the significant influencing factors of fatigue were pain and depression, therefore the development of nursing intervention for relieving pain and depression would be needed.

• Journal of Korean Biological Nursing Science
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• v.5 no.2
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• pp.5-12
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• 2003

Purpose : The purpose of this study was to identify the relationship between fatigue and physiological factors in patients on hemodialysis. Method : Data were collected between June 1 and 7, 2003 using a structured questionnaire which included general characteristics, Visual Analogue scale and laboratory result. Result : Fatigue score changes is the mean of predialysis fatigue score was 4.36 and postdialysis fatigue score 4.66. There were statistically significant differences in score of postdialysis to sex, education and admission. The relationship between predialysis fatigue and interdialytic weight gain showed a positive correlation. The relationship between postdialysis fatigue and Cr showed a negative correlation. Conclusion : Nursing Management program should be developed to fatigue factors in patients on hemodialysis.

• Journal of Society of Preventive Korean Medicine
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• v.19 no.2
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• pp.67-74
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• 2015

Objective : The aim of this study was to investigate fatigue-related factors including socio-demographic variables and life styles among workers in the automobile manufacturing industry. Method : The subjects were 22,937 individuals who had received health examination by Korean Medical doctors and responded to questionnaires for 8 months from March to November in 2011. The fatigue index was measured by heart rate variability (HRV) in an automobile manufacturing industry. A multivariate analysis with SPSS version 19.0 was used to examine the relationship between fatigue and other factors including ages, smoke consumption, drinking frequency, exercise frequency, occupational category, conjugal condition. Results : In comparison between normal and very bad level of fatigue, factors of ages, smoking, drinking, and exercise showed significant difference(p<0.05). In addition, when normal and bad fatigue were compared, ages, smoking, exercise also produced significant difference(p<0.05). Furthermore, in normal and good level of fatigue comparison, occupation and smoking yielded significant difference(p<0.05). Finally, in other comparisons between normal and very good fatigue, exercise, smoking and occupation revealed significant difference(p<0.05). Conclusion : The results of this study suggest that age increase affects fatigue negatively, whereas exercise and drinking of once or twice per a week can have positive correlations.

• Korean Journal of Adult Nursing
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• v.15 no.1
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• pp.33-44
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• 2003

Purpose: The purpose of this study was to identify the patterns and related factors of fatigue in patients with breast cancer undergoing radiotherapy. Method: 31 women with breast cancer receiving radiotherapy were recruited from the out-patient radiologic clinic of the university hospital in Seoul, Korea over a period of 3 months. Data was collected prospectively concerning three points for $5\frac{1}{2}\;-\;6\frac{1}{2}$ weeks : before radiotherapy(T1), 2 weeks after starting radiotherapy(T2) and the completion of radiotherapy(T3). Data were analysed by repeated measure ANOVA, Pearson correlaton, and multiple regression. Result: 1. Score of fatigue increased significantly over the course of radiotherapy. 2. Score of symptom distress and emotional distress increased and functional status scores decreased significantly over time. 3. Fatigue was positively related with symptom distress and emotional distress and negatively related with functional status over the course of radiotherapy. 4. At T2, emotional distress explained 24.7% of the variation in fatigue. At T3, symptom distress(41.9%) and emotional distress(7.2%) explained the variance in fatigue. Conclusion: The results of this study provided evidence that fatigue increased over the course of radiotherapy and symptom distress and emotional distress were influencing factors of fatigue in this group. The results of this study suggest that comprehensive intervention strategy for fatigue should be developed to maintain quality of life during and following radiotherapy considering these factors.

• Research in Community and Public Health Nursing
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• v.22 no.4
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• pp.420-428
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• 2011

Purpose: The purpose of this study was to investigate the relations between fatigue and work-related factors in workers. Methods: A total of 204 subjects aged between 21 and 59 were selected through convenient sampling. Data were collected with a self-reported questionnaire from May 20 to 31, 2011. Collected data were analyzed with SPSS/WIN 17.0. Results: Difference in fatigue according to general characteristics was significant according to duty type. Difference in fatigue according to occupational characteristics was significant according to work intensity, work speed, demand of work concentration, work space, physical environment, largest weight by hands, vibration, visual demand of work, difficulty of work practice, work stress, and rest hours in holiday. There was a positive correlation between fatigue and occupational characteristics. Stepwise multiple regression analyses showed that educational level, work intensity, and rest hours in holiday were the strongest factors associated with fatigue ($R^2$=.363 p<.001). These factors explained fatigue by 36.3%. Conclusion: The findings of this study may be useful in understanding workers' fatigue and developing more specific fatigue relief programs.

• Korean journal of aerospace and environmental medicine
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• v.31 no.2
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• pp.38-44
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• 2021

Purpose: This study aimed to identify the prevalence of fatigue and its associated factors leading to the fatigue among Korean commercial airline pilots. Methods: An anonymous, web-based questionnaire collecting data on sleep related characteristics was completed by airline pilots. The final 1,029 samples of completed questionnaires were analyzed. The association of the risk factors with fatigue was determined using logistic regression analysis. Results: The prevalence of fatigue was 60% (Fatigue Severity Scale index≥3.2), disturbed sleep 28% (Pittsburgh Sleep Quality Index≥9), daytime sleepiness 17% (Epworth Sleepiness Scale≥10), and sleep apnea (Berlin Questionnaire≥2) 11%. The fully adjusted logistic regression showed that quality of life (odds ratio [OR]=0.16, confidence interval [CI]=0.11-0.24), daytime sleepiness (OR=1.26, CI=1.18-1.34), sleep quality (OR=1.44, CI=1.29-1.61), mental workload (OR=1.10, CI=1.05-1.14), vigorous physical activity (OR=0.82, CI=0.72-0.92), late starts (OR=1.25, CI=1.06-1.46) and average weekly flying hours (OR=1.02, CI=1.00-1.03) were associated with higher levels of fatigue. Conclusion: Lower quality of life, disturbed sleep, more subjective sleepiness, shorter sleep duration, higher mental workload, less vigorous physical activity, frequent late starts, and longer flying hour were shown to be risk factors for fatigue in airline pilots. These findings should be taken into account in the development of sleep and fatigue countermeasures for airline pilots.