• Journal of Korean Society of Steel Construction
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• v.9 no.1 s.30
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• pp.95-105
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• 1997

Structures subjected to strong seismic excitation may undergo inelastic deformation cycles. The resulting cumulative fatigue damage process reduces the ability of structures and components to withstand seismic loads. Yet, the present earthquake resistance design methods focus mainly on the maximum displacement ductility, ignoring the effect of the cyclic responses. The damage parameters closely related to the cumulative damage need to be properly reflected on the aseismic design methods. In this study, two cumulative damage assessment methods derived from the plastic fatigue theory are investigated. The one is based on the hysteretic ductility amplitude, and the other is based on the dissipated hysteretic energy. Both methods can consider the maximum ductility and the cyclic behavior of structural response. The validity of two damage methods has been examined for single degree of freedom structures with various natural frequencies against two different earthquake excitations.

• Structural Engineering and Mechanics
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• v.49 no.2
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• pp.203-223
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• 2014

The extensive use of prestressed reinforced concrete (PSC) highway bridges in marine environment drastically increases the sensitivity to both fatigue-and corrosion-induced damage of their critical structural components during their service lives. Within this scenario, an integrated method that is capable of evaluating the fatigue reliability, identifying a condition-based maintenance, and predicting the remaining service life of its critical components is therefore needed. To accomplish this goal, a procedure for fatigue reliability prediction of PSC highway bridges is proposed in the present study. Vehicle-bridge coupling vibration analysis is performed for obtaining the equivalent moment ranges of critical section of bridges under typical fatigue truck models. Three-dimensional nonlinear mathematical models of fatigue trucks are simplified as an eleven-degree-of-freedom system. Road surface roughness is simulated as zero-mean stationary Gaussian random processes using the trigonometric series method. The time-dependent stress-concentration factors of reinforcing bars and prestressing tendons are accounted for more accurate stress ranges determination. The limit state functions are constructed according to the Miner's linear damage rule, the time-dependent S-N curves of prestressing tendons and the site-specific stress cycle prediction. The effectiveness of the methodology framework is demonstrated to a T-type simple supported multi-girder bridge for fatigue reliability evaluation.

• The Journal of Internal Korean Medicine
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• v.28 no.4
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• pp.791-796
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• 2007

Objective : This study was conducted to find the relationship between syndrome-differentiation and Sasang-constitution in chronic fatigue patients. Methods : The subjects were 72 adults with chronic fatigue who visited Dunsan Oriental Hospital of Daejeon University between March 2007 and April 2007. Their main complaint was fatigue for longer than 6 months and they did not have any physical or mental problems. We measured their fatigue degree by using Chalder fatigue scale and health habits. To evaluate relationship between syndrome-differentiation with sasang-constitution, The patients were divided into four syndrome-differentiations, such as liver and kidney asthenia of Yin, spleen and kidney deficiency of Yang, deficiency of lung and spleen qi, and deficiency of heart and spleen blood. We also diagnosed Sasang-constitution by using Questionnaire for Sasang Constitution Classification II (QSCCII). Results : Among the 72 patients, 41.4%, 34.5% and 24.1% of belonged in Soyangin, Soeumin and Taeumin respectively. Interestingly, we found a meaningful correlation between syndrome-differentiation and physiological function by Sasang-constitution. Conclusion : The result may help Oriental medicine understanding and treatment of chronic fatigue-related diseases and patients.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.108-113
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• 2004

According to our fatigue tests carried out at 20 Hz, R=0.1 on transversely butt~welded joints, fatigue strengths of as-welded specimens, that is, specimens having residual stress are higher than those of annealed specimens in short life range, but vice verse in long life range. This behavior seems to be concerned mainly with residual stress relaxation by applied loading. After analyzing the welding process, we conducted finite element analysis to quantify the degree of residual stress relaxation. By taking into account residual stress relaxation, modified Goodman diagram, and nominal stress, we evaluated the fatigue life of the welded joint from the S-N curve for the parent material. The estimated results are in a good agreement with the experimental results.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.141-146
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• 2012

Aluminum alloys have been used with various thicknesses suitable for light weight of structure. It is known that the thickness effect of material is an important factor affecting fatigue crack propagation under constant fatigue stress condition. In this work, we presented the behavior of fatigue crack propagation in thin plate compared to thick plate Al 2024-T3 alloy with referred thickness effect in a correlative equation determined by the shape factor and the loading factor. We chose two factors that are used in the correlative equation with considering that the experiments were carried out under a constant fatigue stress condition. The thickness ratio of thin plate compared to thick plate and the equivalent effective stress intensity factor ratio depending on thickness were chosen as shape and loading factors. A correlative equation is utilized to determine the equivalent effective stress intensity factor range of thin plate and identify the degree of increasing phenomenon of fatigue life in thin plate compared to thick plate.

• Journal of Korean Academy of Nursing
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• v.36 no.6
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• pp.925-932
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• 2006

Purpose: The purpose of this study was to identify the relationship between depression, perceived stress, fatigue and anger in clinical nurses. Method: A descriptive survey was conducted using a convenient sample. Data was collected by questionnaires from four hundred clinical nurses who worked at a university hospital. Radloff's CES-D for depression, Cohen, Kamarck & Mermelstein's Perceived Stress Scale, VAS for Fatigue, and Spielberger's STAXI for anger were used. The data was analyzed using the pearson correlation coefficient, students' t-test, ANOVA, and stepwise multiple regression with SPSS/WIN 12.0. Result: The depression of clinical nurses showed a significantly positive correlation to perceived stress(r=.360, p=.000), mental fatigue(r=.471, p=.000), physical fatigue(r=.350, p=.000), trait anger(r=.370, p=.000), anger-in expression(r=.231, p=.000), and anger-control expression(r=.120, p=.016). There was a negative correlation between depression and age(r=-.146, p=.003). The mean score of depression of nurses, 26, was a very high score and 40.8% of clinical nurses were included in a depression group. The main significant predictors influencing depression of clinical nurses were mental fatigue, trail anger, perceived stress, anger-in expression, and state anger, which explained about 32.7%. Conclusion: These results indicate that clinical nurses with a high degree of perceived stress, mental fatigue and anger-in expression are likely to be depressed.

• Journal of Korean Physical Therapy Science
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• v.4 no.2
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• pp.391-397
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• 1997

The purposes of this study were to determine wether knee muscular fatigue affects on one-leg static standing balance. Sixty four healthy subjects were used for this study : 44 men and 20 women, with an average age of 19.52. One leg static standing balance was measured at pre-fatigue and post-fatigue by an instrumented balance assessment system(kinesthetic ability training balance platform) which is commercially available for testing or training balance. Isokinetic exercises were used to evoke muscle fatigue at 180 degree/see by Cybex 1200. One leg static standing balance ability was significantly decreased after knee muscular fatigue. Although these phenomenons were not clearly understood, these results have important implications for rehabilitation in fatigable patients. These results suggest that the excessive fatiguing during rehabilitation in patients with fatigable disease may increase risk of reinjury and falling injury due to balance disturbance. Further studies are required to determine the physiological mechanisms of muscle fatigue that can play in decreasing one-leg static standing balance ability.

• Child Health Nursing Research
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• v.23 no.4
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• pp.459-469
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• 2017

Purpose: Nurses experience burnout related to various factors. For this descriptive research job stress, compassion satisfaction, and compassion fatigue were examined as to their relationship to burnout in nurses from children's hospital. Methods: The participants were 305 nurses working in children's hospital. Self-report questionnaires were used to measure job stress, compassion satisfaction, compassion fatigue and burnout. Results: Nurses in children's hospital experienced a greater than moderate degree of job stress, compassion satisfaction, compassion fatigue and burnout, whereas differences existed according to general characteristics. Job stress, compassion fatigue and burnout showed a significant positive correlation and results of compassion fatigue and burnout were similar. Also, job stress, compassion satisfaction and compassion fatigue were associated with burnout in nurses working in children's hospital. Conclusion: Findings indicate that as longer work experience is accompanied by higher job stress and burnout, it is necessary to develop intervention programs to reduce burnout among career nurses exposed to greater job stress in children's hospital.

• The Journal of Korean Physical Therapy
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• v.18 no.1
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• pp.1-10
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• 2006

Purpose: This study was to investigate how induced microcurrent shoes affect relief of feet pain, which often occurs to persons who are more than fifty years old and how they prevent fatigue of feet generated during everyday life. The subjects of this study were comprised af five males and five females, who agreed with this research and ate more than fifty years old. And they all have plantar faciitis and pain in their feet. Methods: Subjects ware the induced microcurrent shoes far more than 4 hours everyday during the test. When they wore those shoes, they also wore the specially produced shacks made of silver-mixed thread and they were asked to avoid serious exercise. Prior to starting test and after the test, assessments were carried out two times. In the examination before the test, general shoes were used and in examination after the test, induced microcurrent shoes used. Muscle fatigue was measured by electromyography(MP150, Biopac, USA). When the walking rate of subjects on a treadmill was increased from 2.Km/h to 3Km/h for 10 minutes, muscle activities of a lower leg were measured during the whale walking process by MP150 remote monitoring system(TEL 100C). And pain was measured by VAS. Results: The results are as follows. 1. Comparisons of VAS before and after experimentation showed that degree of pain was significantly decreased(p < .05). 2. Degree of fatigue of Tibialis anterior was significantly decreased after 6 weeks of treatment(p < .05). 3. Degree of fatigue of Soleus was slightly decreased after 6 weeks of treatment, but did not show significant difference (p > .05). Conclusion: The above results suggest that induced microcurrent shoes is helpful decreasing fatigue of feet and relief of feet pain.

• Women's Health Nursing
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• v.7 no.4
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• pp.461-472
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• 2001

A study was done to identify mothers' perception of fatigue in postpartum period. Questionnaires were collected from 267 normal postpartum mothers in Korea from July to December 2000. The questionnaires used to measure mothers' fatigue were "Subjective Symptoms of Fatigue Test" designed by Research Committee of Industrial Fatigue in Hygienic Association of Japan Industry. The collected data were analyzed by SPSS-Win. The results revealed that The average fatigue score of subjects was 1.70; Physical fatigue had the highest value with a mean of 1.89, followed by psychological fatigue with a mean score of 1.62, neuro-sensory fatigue was rated lowest with a mean of 1.58. Sorting out the subjects fatigue level per a week during Sweeks, 6th week after postpartum had the highest value with a mean of 1.85. Degree of fatigue was also compared with the respect to the general characteristics of mothers: There were statistically significant differences according to mothers' job (t=-2.021, p=.046), sleeping time (t=2.771, p=.006), having a nap (t=-2.132, p=.034), baby character (F=3.089, p=.047), baby sex (t=-2.054, p=.041), having a person who help domestic affairs (t=2.292, p=.023). Therefore variable nursing intervention should be provided to alleviate the fatigue according to the postpartum period. Especially the nursing intervention program to alleviate the physical fatigue is needed.