• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.1-4
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• 2001

A new non-destructive fatigue prediction model of the composite laminates is developed. The natural frequencies of fatigue-damaged laminates under extensional loading are related to the fatigue lift of the laminates by establishing the equivalent flexural stiffness reduction as a function of the elastic properties of sublaminates. The flexural stiffness is derived by relating the $90^{\circ}$-ply elastic modulus reduction, and using the laminate plate theory to the degraded elastic modulus and the intact elastic modulus of other laminate. The natural frequency reduction model, in which the dominant fatigue mode can be identified from the sensitivity scale factors of sublaminate elastic properties, provides natural frequency vs. fatigue cycle curves for the composite laminates. Vibration tests were also conducted on $[\textrm{90}_{2}\textrm{0}_{2}]_s$ carbon/epoxy laminates to verify the natural frequency reduction model. Correlations between the predictions of the model and experimental results are good.

• Journal of Ocean Engineering and Technology
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• v.20 no.5 s.72
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• pp.82-88
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• 2006

This assessment is concerned with the fatigue strength of the tendon porch found in TLP. Lorge-scale fatigue tests with models constructed at 30% the size of the real structures have been carried out to investigate the fatigue behavior of the API 2W Grade 50 steel recently produced by POSCO. The fatigue life for the present test models was obtained based on the concept of nominal stress. A comparison of the present test results with those obtained by a numerical approach based on the structural analysis results has showngood agreement. The present results were also compared with the design curves in DnV RP-C203.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.648-653
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• 2007

In this study, we have generated fatigue load spectrum that is using to prediction of life time for the helicopter rotor blades. We derive utility helicopter missions for the sake of generating load spectrum. Helix and Felix are standard loading sequences which relate to the main rotors of helicopters with articulated and semi-rigid rotors respectively. We got scale factors which is applied to specific case and it did be obtained through the finite element analysis tools. The fatigue life of the rotor blade is estimated by using MSC/Fatigue. We suggest that generated our fatigue load spectrum in conjunction with small utility helicopter should use to rotor blade fatigue test of the korea helicopter program.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.12
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• pp.2055-2060
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• 2003

Striation is a typical pattern observed on the fatigue fracture surface and the spacing is known to correspond to a macroscopic fatigue crack growth rate, and many models for the predict in the formation of such striation have been proposed. However, these theories and methods can't be applied under random loading spectrum. In this study, the fatigue tests were carried out on aluminum alloy under random loading spectrum. The fatigue fracture surfaces were observed in the scanning electron microscope (SEM) and great quantities of SEM micrographs were synthesized and saved in computer system. The space and morphology of several large-scale striations, which are expected to from at the relatively greater load range in loading block, were observed. The crack length for each loading blocks was decided in consideration of regularity and repetition of those striations. It is shown that the applicability of fractographic methods on the fatigue fracture surface under random loading spectrum.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.1
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• pp.199-206
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• 2003

This paper presents the fatigue life of transverse joint of concrete pavement with the fatigue model test. A 1/12 scale model was used to satisfy the geometric load, material similitude, which are variables to the skew angel of transverse joint. From the test results by fatigue load 700kgf applied, we can have that the fatigue life of transverse joint with skew angle is better than that of transverse joint without skew angle. In addition, we can have that the fatigue life of skewed transverse joint with angle of 10 degree is better than that of skewed transverse joint with angle of 20 degree.

• Korean Journal of Occupational Health Nursing
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• v.21 no.3
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• pp.229-238
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• 2012

Purpose: The purpose of this study was to measure the fatigue of operating room nurses and examine factors contributing to their fatigue. Methods: The subjects of this study were 115 nurses who worked in operating rooms of three hospitals. Data were collected from September 15, 2009 to September 30, 2009. Fatigue and job stress were measured by using the Symptom's Fatigue Scale and the job stress measurement tools in operating room nurses. Results: The mean score of fatigue level was $3.10{\pm}0.61$. We analyzed fatigue according to characteristics of subjects and found that there were significant differences in marital status, number of children and sleeping hours in general characteristics. Career, daily participation hours in the surgery relating to job related characteristics. Significant positive correlations were found between job stress and fatigue(r=.233, p= .012). Three significant variables influencing fatigue of operation rooms nurses were job stress, daily participation hours in the surgery, and sleeping hours (Adj. $R^2$=0.284, F=4.773, p<.001). Conclusion: An integrative care program that takes job stress, daily participation hours in the surgery and sleeping hours into consideration is essential to reduce fatigue in operating room nurses.

• Asian Oncology Nursing
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• v.7 no.1
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• pp.3-13
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• 2007

Purpose: The purpose of this study was to identify the relationship of fatigue and functional status in patients with cancer. Method: The data were collected from August, 15 to October, 10, 2005. The subjects were recruited from three university hospitals and two general hospitals in B, U, and S cities in Korea. Fatigue was measured using the Fatigue Scale for Cancer Patients, and Functional Status was measured using the Karnofsky Performance Status Index. Result: 1) The mean score of fatigue was $79.72{\pm}21.25$(range: 26-130), and the mean score of functional status was $79.33{\pm}13.02$. 2) There were significant differences in the scores of fatigue by sex, age, marital status, employment, major care-giver, pain, and period after diagnosis. 3) There were significant differences in the scores of functional status by employment, major care-giver, pain, stage of cancer, period after diagnosis, and type of cancer. 4) There was a significant negative correlation between fatigue and functional status (r= -.472, p= .000). Conclusion: Increase in fatigue was associated with decrease in functional status in patients with cancer. Nurses must assess fatigue and functional status when caring for the cancer patients, and provide nursing intervention to relieve fatigue and to improve functional status.

• Asian Oncology Nursing
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• v.5 no.2
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• pp.87-96
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• 2005

Purpose: The purpose of this study was to identify the relationship between fatigue and nutritional status in gastric cancer Design. A correlational and crossectional study design was used. Method: Fatigue was measured using the Revised Piper Fatigue Scale. The parameters for nutritional status consisted of BMI, Hb, Hct, total protein, albumin and lymphocyte count. Result: The mean score of fatigue was $94.31{\pm}22.08(mean\;average\;4.48{\pm}1.00)$. The subdimensional scores of fatigue revealed $34.15{\pm}8.76$ for behavior/severity, $22.00{\pm}7.93$ for cognitive/mood, $21.67{\pm}5.56$ for sensory, and $20.81{\pm}6.69$ for affective. And the level of BMI, Hb, & Hct were under the normal ranges. In the ancillary analysis, there was a significant difference on the fatigue scores by the groups of present diet(F=3.343, P=.026). Age, types of treatments, period after diagnosis and weight change were related to nutritional status. There was a significant negative correlation between fatigue and nutritional status(r=-.371, P=.004). Conclusion: Considering the relationship between fatigue and nutritional status, nurses can identify the risk group most vulnerable to fatigue and malnourishment in order to provide appropriate interventions for them.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.543-554
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• 2016

This study examined the fatigue and its association with job stress among male workers engaged in small-scale manufacturing industries. The study subjects were 553 male workers under 50 members of manufacturing industries. The study survey was a structured questionnaire of the Korean Occupational Stress Scale (KOSS) and Multidimensional Fatigue Scale (MFS) during April, 2015. The data were analyzed using the SPSS ver 21.0 program. The results showed that the high risk fatigue group was significantly higher in the high risk group of job stress than in the normal group of job stress. Fatigue was positively correlated with job stress. The odds ratio of the high risk fatigue group were increased significantly in the high risk group of job stress than in the normal group of job stress. The factors of influence with explanatory powers of 27.7% on fatigue included age, marital status, educational level, subject health status, sleeping time, drinking coffee, job tenure, shift work, visiting out-patient department, sense of satisfaction in job life, and job stress. Fatigue was associated with the sociodemographic characteristics, health behavior related characteristics, job-related characteristics, and job stress.