• Steel and Composite Structures
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• 제43권4호
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• pp.465-481
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• 2022

This paper presents a comprehensive integrity assessment of welded structural components, including uniform high- and low-cycle fatigue assessment of welded plate joints and fatigue-induced fracture assessment of welded plate joints. This study reports a series of fatigue and fracture tests of welded plate joints under three-point bending. To unify the assessment protocol for high- and low-cycle fatigue of welded plate joints, this study develops a numerical damage assessment framework for both high- and low-cycle fatigue. The calibrated damage material parameters are validated through the smooth coupon specimens. The proposed damage-based fatigue assessment approach describes, with reasonable accuracy, the total fatigue life of welded plate joints under high- and low-cycle fatigue actions. Subsequently, the study performs a tearing assessment on the ductile crack extension of the fatigue-induced crack. The tearing assessment diagram derives from the load-deformation curve of a single-edge notched bend, SE(B) specimen and successfully predicts the load-crack extension relation for the reported welded plate joints during the stable tearing process.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2600-2609
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• 2021

Low cycle fatigue behaviors of SA508-3 low-alloy steel were investigated in room-temperature air, high-temperature air and in light water reactor (LWR) water environments. The fatigue mean curve and design curve for the low-alloy steel are developed based on the fatigue data in room-temperature and high-temperature air. The environmental fatigue model for low-alloy steel is developed by the environmental fatigue correction factor (F_en) methodology based on the fatigue data in LWR water environments with the consideration of effects of strain rate, temperature, and dissolved oxygen concentration on the fatigue life.

• Asian Pacific Journal of Cancer Prevention
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• 제15권22호
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• pp.9891-9898
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• 2014

Background: This study was planned in an attempt to develop scales for the assessment of fatigue in pediatric oncology patients aged 13-18 and also for their parents. Materials and Methods: In collecting the study data, we used the Child and Parent Information Form, Visual Fatigue Scale, Scale for the Assessment of Fatigue in Pediatric Oncology Patients Aged 13-18 and the Scale for the Assessment of Fatigue in Pediatric Oncology Patients Aged 13-18 for Parents. We also used Pearson correlation analysis, Cronbach alpha coefficient, factor analysis and ROC analysis for the study data. Results: In this study, the total Cronbach alpha value of the parent form was 0.99, the total factor load was 0.72-0.94 with 95% the total variance being explained. The cutoff point of the parent form is 73 points. The total Cronbach alpha value of the child form was 0.99, the total factor load was 0.82-0.95, with 89.4% of the total variance being explained. The cutoff point of the child form was 75.5 points. Conclusions: This study suggests that the Scale for the Assessment of Fatigue in Pediatric Oncology Patients Aged 13-18 and the Scale for the Assessment of Fatigue in Pediatric Oncology Patients Aged 13-18 for Parents are valid and reliable instruments in assessing the fatigue symptoms of children in Turkey.

• 한국항공운항학회지
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• 제27권2호
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• pp.47-53
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• 2019

The development of the aviation industry and the changes in the military operation mission environment are demanding more long - distance operation (long - time flight), and such a flying environment is a risk factor for fatigue - related accidents. For the aviation related organizations such as ICAO and FAA, fatigue risk management system (FRMS) are applied along with flight time restriction regulations to prevent fatigue related accidents. The most important process in FRMS is fatigue risk management. Fatigue risk management systematically manages fatigue through scientific fatigue risk data collection and fatigue risk assessment. The purpose of this study is to applicate the assessment of scientific fatigue risk management to pilots of airplanes engaged in long flight. We reviewed the current state of risk management and FRMS through previous research. We also developed fatigue risk management indicators and examined the validity of internationally recognized fatigue risk data collection methods and fatigue risk assessment tools. There are 134 mission (flight) data used for development. In order to verify the indicators, the fatigue risk score between the items was assigned through pair-wise comparison. In addition, the verify test results were normalized.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1125-1131
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• 2009

This paper presents the evaluation of fatigue life for a journal box attached to rolling stock bogie under random dynamic loading condition. Because a journal box was under random dynamic loading conditions, the fatigue life assessment due to these loads requires the analysis considering the multiaxial effect of random dynamic loading. To do this work, the finite element analysis has been conducted to calculate random dynamic response using multiaxial acceleration data. Then, the fatigue life assessment of component has been conducted using vibration fatigue analysis applying the power spectral densities of the responses obtained through the FEA The results of fatigue life assessment were compared to the damage from the strain measurement. This study shows that can be evaluated the fatigue life assessment considering real service condition about a component attached to rolling stock bogie.

• 한국안전학회지
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• 제14권2호
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• pp.11-18
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• 1999

Proper fatigue life prediction procedures are needed for mechanical structures which requires high durability and reliability. In this paper, a fatigue life prediction procedure has been developed for predicting fatigue life of moving structure under variable loadings. The developed procedure was efficiently applied for a fatigue life calculation of a container crane. Especially, the procedure is useful for safety assessment by computer simulation. A computer program was developed for fatigue life assessment by adopting the forementioned procedure.

• 국제강구조저널
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• 제18권4호
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• pp.1242-1251
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• 2018

Not all loads contribute to fatigue crack propagation in the welded detail of steel bridges when they are subjected to variable amplitude loading. For fatigue assessment, therefore, non-contributing stress cycles should be truncated. However, stress range truncation is not considered during typical fatigue reliability assessment. When applying the first order reliability method, stress range truncation occurs mismatch between the expected number of cycles to failure and the number of cycles obtained at the time of evaluation, because the expected number of cycles only counts the stress cycles that contribute to fatigue crack growth. Herein, we introduce a calibration factor to coordinate the expected number of cycles to failure to the equivalent value which includes both contributing and non-contributing stress cycles. The effectiveness of stress range truncation and the proposed calibration factor was validated via case studies.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.264-268
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• 2008

An assessment of creep-fatigue crack behavior is required to ensure the structural integrity for high temperature components such as fast breeder reactor structures or thermal power plant components operating at an elevated temperature. In this study, an evaluation of creep-fatigue crack growth has been carried out according to the French assessment guide of the RCC-MR A16 for austenitic stainless steel structures. The assessment procedures for creep-fatigue crack growth in the recent version of the A16 (2007 edition) have been changed considerably from the previous version (2002 edition) and the material properties (RCC-MR Appendix A3) have been changed as well. The impacts of those changes on creep-fatigue crack growth behavior are quantified from the assessments with a structural model. Finally the assessment results were compared with the observed images obtained from the structural tests of the same structural specimen.

• Safety and Health at Work
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• 제12권4호
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• pp.462-470
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• 2021

Background: Fatigue is pervasive, under-reported, and potentially deadly where flight operations are concerned. The aviation industry appears to lack a standardized, practical, and easily replicable protocol for fatigue risk assessment which can be consistently applied across operators. Aim: Our paper sought to present a framework, supported by real-world data with subjective and objective parameters, to monitor aircrew fatigue and performance, and to determine the safe crew configuration for commercial airline operations. Methods: Our protocol identified risk factors for fatigue-induced performance degradation as triggers for fatigue risk and performance assessment. Using both subjective and objective measurements of sleep, fatigue, and performance in the form of instruments such as the Karolinska Sleepiness Scale, Samn-Perelli Crew Status Check, Psychomotor Vigilance Task, sleep logs, and a wearable actigraph for sleep log correlation and sleep duration and quality charting, a workflow flagging fatigue-prone flight operations for risk mitigation was developed and trialed. Results: In an operational study aimed at occupational assessment of fatigue and performance in airline pilots on a three-men crew versus a four-men crew for a long-haul flight, we affirmed the technical feasibility of our proposed framework and approach, the validity of the battery of assessment instruments, and the meaningful interpretation of fatigue and work performance indicators to enable the formulation of safe work recommendations. Conclusion: A standardized occupational assessment protocol like ours is useful to achieve consistency and objectivity in the occupational assessment of fatigue and work performance.

• 대한간호학회지
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• 제27권3호
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• pp.489-502
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• 1997

Quality of life(QOL) and fatigue in cancer patients receiving the radiotherapy was assessed. The subjects were 46 cancer patients who daily attended the radiotherapy department. Assessment was done on four occassions : the first assessment was done on the treatment simulation visit, the second one was four weeks after treatment started, the third one at the completion of treatment and the last assessment was done between six and eight week following treatment. The results are as follows : The fatigue scores of the patients at each stage of assessment ranged from 5.49 points to 7.67 points and highest score was recorded at the third assessment that is, at the completion of treatment. The fatigue points showed an increase from the 1st. to 3rd. stage. However, at the 4th. stage, fatigue points decreased to the level at the first stage of assessment. QOL were assessed in three areas namely, physical, emotional and social /functional. The QOL scores in the physical area showed the highest score, followed by social /functional and emotional areas. The QOL scores decreased gradually to the third. stage of assessment thereafter recovered to the level of the first. stage. Correlation between QOL and fatigue scores during the treatment indicated that the level of QOL decreased as the level of fatigue increased. In particular, fatigue persisted after completion of the treatment and showed a significantly negative correlation with QOL. The present study strongly suggests that a strategy to restore the emotional well being level of the patient should be devised in order to improve QOL and reduce fatigue of patients receiving radiotherapy.