• Advances in concrete construction
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• 제12권5호
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• pp.411-418
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• 2021

Roller compacted concrete (RCC) used in the island reef airport runway will be subjected to the coupling actions of the fatigue impacts and the salt spray cycles, which will accelerate the deterioration of runway concrete and even threaten the flight safety. A cyclic impact testing machine and a climatic chamber were used to simulate the low-velocity fatigue impact and the salt spray cycles, respectively. The physical properties, the microstructures and the porosity of RCC were investigated. The results show the flexural strength firstly increases and then decreases with the increase of the fatigue impacts and the salt spray cycles. However, the decrease in the flexural strength is significantly earlier than the compressive strength of RCC only subjected to the salt spray cycles. The chlorine, sulfur and magnesium elements significantly increase in the pores of RCC subjected to 30000 fatigue impacts and 300 salt spray cycles, which causes the decrease in the porosity of RCC. The coupling effects of the fatigue impacts and the salt spray cycles in the later period accelerates the deterioration of RCC.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.1025-1028
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• 2005

Generally, fiber-reinforced composites have the highest possibilities of impact damages with external object collisions. Also, resulting in fatigue fracture considering the continued impact load. For the reasons mentioned above, the accurate understanding of interactions between the impact of composites and the fatigue load will be essential to understand the safety level of material structures. Furthermore, the composite materials and structures, due to the geometrical effect, vary the life in connection with the impact-fatigue. Therefore, I have reached the point that a focus of this study will be to evaluate fatigue fracture characteristics by the impacts-fatigue load of fiber-reinforced composites. Thus, in this paper, I have tried to work on impacts-fatigue load causing aspects and impact characteristics through impact-fatigue test on HTV-5Hl Black 9250 material made- structure, along with to evaluate the expected lift of real structures, the FEM analysis was carried out.

• 한국임상보건과학회지
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• 제6권2호
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• pp.1156-1170
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• 2018

Purpose. This study was conducted to analyze fatigue and subjective oral health status in the employees in educational institutions and provide basic data for the development of a program for the promotion of oral health. Methods. As for the subjects, this study conducted a survey with 468 educational personnel in elementary, middle, and high schools in the Daegu-Gyeongbuk area from March through June 2016 and utilized 407 copies finally. As for the items on the survey, this study conducted an investigation on their general characteristics, fatigue, and subjective oral health status(halitosis, xerostomia, temporomandibular disorder) with the self-administered method. With the data collected, this study conducted frequency analysis, t-test, ANOVA, and multiple regression analysis, using SPSS 20.0 statistical program, and the statistical significance level was .05. Results. As a result of this study, it turned out that by sex, fatigue was higher in women(4.59 points); by the place of work, those in 'elementary school' had higher fatigue(4.59 points); and by health condition and oral health status, most of them responded that they were 'not healthy'(4.81 and 4.84 points, respectively) and there was a statistically significant difference (p<.05). As for the correlation between fatigue and subjective oral health status, there were positive(+) impacts on halitosis(=.248, p<.001), xerostomia(=.097, p<.05), and temporomandibular disorder(=.148, p<.01), so it turned out that there was a correlation between fatigue and subjective oral health status. Conclusion. Based on the result of an analysis of the impacts of the fatigue level on subjective oral health status, it is judged that it would be necessary to continue to build up a program that can promote the oral health status of the educational personnel. In addition, it is necessary to conduct studies continuously for the development and application of a program for the change in lifestyle and behavior that can lower their fatigue.

• 한국콘텐츠학회논문지
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• 제20권7호
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• pp.547-559
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• 2020

소셜네트워크 시스템(SNS)은 긍정적인 영향과 부정적인 영향을 동시에 주고 있으며, 사람들의 생활과 뗄 수 없는 존재가 된 지 오래되었다. 본 연구에서는 서로 다른 문화권 남녀들의 SNS 피로감을 분석함과 동시에 그러한 피로감이 SNS를 중단하려는 의도와는 어떠한 관계가 있는지도 알아봤다. 연구결과, (a) 여성들이 SNS 활동으로 인한 상대적 박탈감과 평판 걱정, (b) 동양 문화권의 참여자들은 관계 부담, (c) 서양 문화권의 참여자들은 사생활 염려에 관한 피로감을 느끼고 있는 것으로 드러났다. 마지막으로 SNS 피로감과 중단 의도는 통계적인 유의한 관계가 없었으며, 이는 사람들이 피로감을 느낌에도 불구하고 SNS를 중단하고 싶은 마음은 없다는 것으로 해석된다. 이번 연구에서 문화와 성별이 SNS에 대한 사람들의 피로감에 영향을 준다는 것을 밝혔으며, 피로감에도 불구하고 일부의 사람들만이 SNS를 중단한다는 것이 드러났다.

• 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.

• 대한기계학회논문집A
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• 제33권2호
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• pp.99-107
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• 2009

This study produced a design curve and fatigue limit for a variation in volume ratio and reduction ratio of TiNi/Al composites. In many cases, stress-life curve does not indicate fatigue limit, so it was presented by probabilistic-stress-life curve. Goodman diagram was used to analyze the fatigue strength of materials with a finite life determined by repeated load and the fatigue strength of endurance limit with an infinite life. The fatigue experiment was conducted using the scenk-type plane bending specimen in same shape. The result of the fatigue test, which had been conducted under consistent stress amplitude, was examined. (i) The optimal condition for TiNi/Al in accordance with hot pressing (ii) Impacts of fatigue limit caused by a variation in reduction ratio and volume ratio of TiNi/Al composites (iii) Probability distribution for fatigue limit of TiNi/Al2024 and TiNi/Al6061.

• 동서간호학연구지
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• 제27권2호
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• pp.185-194
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• 2021

Purpose: This study aimed to investigate the effects of fatigue, anxiety, depression, and cognitive function on the quality of life of gastrointestinal cancer patients receiving chemotherapy. Methods: Data were collected from a total of 141 participants. The measurements used were Functional Assessment of Chronic Illness Therapy for fatigue (FACIT-F), Hospital Anxiety and Depression Scale (HADS) and Functional Assessment of Cancer Therapy for cognitive function (FACT-Cog). Results: Significant correlations were found among fatigue, anxiety, depression, cognitive function, and quality of life. The mean score of quality of life was 59.60 out of 108, and 68% of the variance in QOL was explained by fatigue, anxiety, depression, and cognitive function. Cognitive function was the most influential factor (β=.30), followed by anxiety (β=-.27), depression (β=-.24), and fatigue (β=-.18). We found that the better the cognitive function, the lower the anxiety and depression, and the lower the degree of fatigue, the higher the quality of life. Conclusion: A nursing program for managing the changes in fatigue, anxiety, depression, and cognitive function should be provided to enhance maintenance and the improvement of the quality of life for gastrointestinal cancer patients who receive chemotherapy.

• 종양간호연구
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• 제12권1호
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• pp.27-34
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• 2012

Purpose: This study was conducted to identify the impact of fatigue, pain, anxiety and depression on the quality of life (QOL) among breast cancer patients. Methods: This study was conducted from July 12th to July 20th, 2010. One hundred and fifty breast cancer patients were recruited from D city in Korea. The instruments used in this study were the fatigue, pain, anxiety, depression and the quality of life scales for patients with breast cancer. Data were analyzed using descriptive statistics, t-test, ANOVA, Pearson correlation coefficients and multiple regression with the SPSS/WIN 12.0 program. Results: The quality of life for cancer patients showed a significant relationship with fatigue, pain, anxiety and depression. The significant factors influencing quality of life were fatigue, pain, anxiety and depression that explained 65.6% of the variance. Conclusion: Patients with breast cancer experienced fatigue, pain, anxiety and depression which led to a negative effect on quality of life. The results suggest that intervention programs to reduce fatigue, pain, anxiety and depression could improve the quality of life for breast cancer patients.

• 대한조선학회 특별논문집
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• 대한조선학회 2017년도 특별논문집
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• pp.80-87
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• 2017

This paper is related to structural assessment considering the hydroelastic response of ultra large container ships, especially from whipping (bow or stern impacts) and from springing (resonance). In general, whipping contributes both to increased fatigue and extreme loading, while springing does mainly contribute to increased fatigue loading. To evaluate the hydroelastic response quantitatively with high accuracy, numerical code considering hydro-structure coupling was applied and fatigue strength of a 13,100 TEU class containership was verified. The segmented model test and full scale measurement were also needed to assess the effect of whipping and springing on the fatigue and extreme capacity in more realistic way and for verification of the numerical tools. With reference to class rule, fatigue assessment considering springing effect and extreme assessment considering whipping effect were introduced.

• 한국기계가공학회지
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• 제19권6호
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• pp.9-16
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• 2020

This study aims to assess the effects of specimen thickness (ST) on fatigue crack growth in the early stages of crack propagation and near failure in magnesium alloys. The analysis of variance (ANOVA) method was adopted because fatigue crack propagation in magnesium alloys exhibits statistical behavior. The equality of variance test and residual diagnostics were performed on the grown cracks to confirm the validity of ANOVA by verifying the normal distribution and mutual independence of the residuals and their homoscedasticity. ANOVA confirmed that ST heavily impacts crack growth; i.e., when ST is smaller, cracks grow faster in the early crack propagation stage and break more quickly before the formation of larger cracks. We found that ST significantly affects fatigue crack growth in the early crack propagation stage and near the failure stage in magnesium alloys. The regression model was also used to predict crack formation near the failure stage.