• Nuclear Engineering and Technology
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• v.45 no.7
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• pp.929-940
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• 2013

Environmental fatigue of the metallic components in light water reactors has been the subject of extensive research and regulatory interest in Korea and abroad. Especially, it was one of the key domestic issues for the license renewal of operating reactors and licensing of advanced reactors during the early 2000s. To deal with the environmental fatigue issue domestically, a systematic test program has been initiated and is still underway. The materials tested were SA508 Gr.1a low alloy steels, 316LN stainless steels, cast stainless steels, and an Alloy 690 and 52M weld. Through tests and subsequent analysis, the mechanisms of reduced low cycle fatigue life have been investigated for those alloys. In addition, the effects of temperature, dissolved oxygen level, and dissolved hydrogen level on low cycle fatigue behaviors have been investigated. In this paper, the test results and key analysis results are briefly summarized. Finally, an on-going test program for hot-bending of 347 stainless steel is introduced.

• Research in Community and Public Health Nursing
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• v.31 no.4
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• pp.447-458
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• 2020

Purpose: The purpose of this study was to identify the effects of auricular acupressure therapy on sleep disorder and fatigue in menopausal women. Methods: The study design was a non-equivalent control group pretest-posttest design. The participants were 40~60 years old women, assigned to the experimental group (n=25) or the control group (n=27). Auricular acupressure using vaccaria seeds was administered to the experimental group. The sessions continued for 6 weeks. Outcome measures included Pittsburgh sleep quality index, sleep meter, sleep diary, fatigue assessment instrument, serum cortisol, and serum serotonin. Results: Menopausal women in the experimental group showed significant increases in deep sleep, light sleep, serotonin level and sleep duration compared with the control group. Also, the experimental group reported decreases in PSQI, sleep latency, awakening time, fatigue and cortisol level compared with the control group. Conclusion: Results show that auricular acupressure using vaccaria seeds is considered as an effective treatment for sleep disorder and fatigue in menopausal women. We conclude that it can be used as a nursing intervention method proven to reduce sleep disorder and fatigue in menopausal women.

• Journal of Korean Academy of Nursing
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• v.45 no.4
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• pp.587-594
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• 2015

Purpose: To identify the effects of foot reflexology massage on fatigue, stress and depression of postpartum women. Methods: A nonequivalent control group pre-post design was used. A total of 70 women in a postpartum care center were recruited and were assigned to the experimental group (35) or control group (35). Foot reflexology massage was provided to the experimental group once a day for three days. Data were collected before and after the intervention program which was carried out from December, 2013 to February, 2014. Data were analyzed using Chi-square test, Fisher's exact test, and t-test. Results: The level of fatigue in the experimental group was significantly lower than the control group (t= - 2.74, p=.008). The level of cortisol in the urine of women in the experimental group was significantly lower than the control group (t= - 2.19, p=.032). The level of depression in the experimental group was significantly lower than the control group (t= - 3.00, p=.004). Conclusion: The results show that the foot reflexology massage is an effective nursing intervention to relieve fatigue, stress, and depression for postpartum women.

• Korean Journal of Pharmacognosy
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• v.47 no.3
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• pp.258-263
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• 2016

In this study, we tested anti-fatigue effect of Kyung-Ok-Ko (KOK). We examined the exercise performance effects of KOK (600 mg/kg) at 2nd, 3rd and 4th week. The exercise performance of KOK treated group was significantly improved than that of vehicle control (VC) group on grip strength (2nd week), exhausted time of treadmill (3rd week) and exhausted time of weight loaded swimming (4th week). We also investigated the effects of KOK on the change of fatigue parameters in blood, skeletal muscle and liver after swimming exercise. KOK significantly reduced lactate level and enhanced glucose level in blood. Equally KOK significantly increased glycogen in skeletal muscle. However, the glycogen level of KOK in the liver was not significantly increased compared to VC group. These results show that supplementation of KOK may improve the anti-fatigue activity and exercise capacity.

• Korean Journal of Occupational Health Nursing
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• v.8 no.2
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• pp.162-168
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• 1999

To investigate industrial fatigue and low back pain, the questionaire survey for subjective symptoms of fatigue and low back pain was carried out 305 nurses in general hospital in Korea. Nurses participated to this study were divided into low back pain group(LBP) and control group, according to the self-reports by written questionaires. The subjective sysptoms of fatigue comprised three groups of 10 items each, representing dullness and sleepiness(level of cerebral activation), difficulty in concentration(level of motivation) and bodily projection of fatigue. The resultant data were processed for $x^2$-test, t-test to confirm the associations. The results were as follows: 1. 28 items of fatigue subjective symptoms exept two item, 'feel thirsty and 'feel ill', were directly associated with low back pain. 2. The percentage of fatigue complaint were significantly higher in LBP group than control. 3. Of the 30 items of fatigue subjective symptoms, the highest percentage was accounted for 'legs feel heavy', 'eye strain', 'feel stiffness in the neck or the shoulders' followed by 'feel like lying', 'whole body feels tired', 'feel a pain in the low back', 'feel drowsy' and in the order of sequence. 4. The average weighted score for the first group of fatigue items(dullness and sleepiness) was the largest among three groups and was followed by the second group(difficulty in concentration) and the third group (bodily projection of fatigue) in the order of sequence, suggesting the heavier mental and shift work stress of the female workers.

• Physical Therapy Korea
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• v.6 no.3
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• pp.22-37
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• 1999

It was recently reported that exercise-induced fatigue is related to joint position sense although some controversy remains. The purposes of this study were to examine the effect on the accuracy of reproducing the knee angles after a fatiguing isokinetic quadriceps exercise at four different levels (10%, 30%, 50%, and 70% of maximal force) and to find the optimal exercise level without causing knee joint proprioception impairment. Forty healthy women, ages 19 to 27, were randomly assigned to four experimental groups. Before and after the exercise, accuracy of positioning with respect to auditory feedback for specific angles was estimated by calculating the mean errors between specific angles and reproduction angles. Fatigue was measured by EMG signals displayed by a frequency spectrum analysis during the quadriceps exercise. Results showed that there was no significant difference in accuracy of the knee joint positioning sense following the exercises in group 1, group 2, and group 3 (10%, 30%, and 50% of maximal force, respectively); the exception being group 4 (70%). Fatigue level was significantly increased in group 4 but there were no significant increases of fatigue level in group 1, group 2, or group 3. The results concluded that the optimal exercise level to acquire the therapeutic exercise effectiveness without position sense impairment was at 50% of maximal force. Further studies using large sample size and patient groups with poor knee joint proprioception would be needed to confirm this conclusion and to clarify the possibility of clinical applications.

• Korean Journal of Adult Nursing
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• v.23 no.4
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• pp.386-396
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• 2011

Purpose: This study was conducted to examine the level of physical activities at time points of pre-illness and current treatment, and the differences in body mass index (BMI), anxiety, depression and fatigue according to their physical activity in cancer patients undergoing chemotherapy. Methods: The survey was used with 126 cancer patients undergoing daily chemotherapy at injection room, cancer clinic of C University Hospital in G city. Data were collected from June to September, 2009 using a structured questionnaire. The data were analyzed by descriptive statistics, chi-square, Fisher's exact test and t-test using SPSS/WIN15.0. Results: The significant increase in physical activity was reported from pre-illness to the time in treatment (${\chi}^2$=69.027, p<.001). The anxiety level of the group with increased physical activity was significantly lower than those who did not (t=-2.218, p =.028). There were no significant differences in BMI, depression, and fatigue according to physical activity. Conclusion: The level of physical activity was significantly associated with the anxiety level of the cancer patients undergoing chemotherapy. Cancer patients should been encouraged regular physical activity during chemotherapy treatment. And an appropriative nursing intervention should be established in order to motivate cancer patients to increase physical activity.

• Journal of Ocean Engineering and Technology
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• v.6 no.1
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• pp.140-147
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• 1992

Corrsion fatigue test was performed under rotated bending in 3.5% NaCl aqueous solution having a temperature from 278.deg.K in order to investigate the effects of aqueous solution remperature on the corrosion fatigue fracture of raw material steel(SS41) and dual phase steel that was produced from SS41 by a series of heat treatment. Corrosion fatigue life decreases remarkably with increase in solution temperature or with decrease in stress level. The corrosion fatigue life and the crack propagation rate at 303.deg.K show the similar behaviors with those at 318.deg.K, which is assumed to be caused by concentration polarization phenamena. The number and the lengths of microcracks increase with increase in solution temperature, so they lead to the decrease in corrosion fatigue life.

• Steel and Composite Structures
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• v.23 no.2
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• pp.239-250
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• 2017

In the concept of two-parameter fatigue failure criterion, the material fatigue failure is determined by the damage degree and the current stress level. Based on this viewpoint, a residual strength degradation model for stud shear connectors under fatigue loads is proposed in this study. First, existing residual strength degradation models and test data are summarized. Next, three series of 11 push-out specimen tests according to the standard push-out test method in Eurocode-4 are performed: the static strength test, the fatigue endurance test and the residual strength test. By introducing the "two-parameter fatigue failure criterion," a residual strength calculation model after cyclic loading is derived, considering the nonlinear fatigue damage and the current stress condition. The parameters are achieved by fitting the data from this study and some literature data. Finally, through verification using several literature reports, the results show that the model can better describe the strength degradation law of stud connectors.

• Journal of Ship and Ocean Technology
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• v.11 no.1
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• pp.25-35
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• 2007

This paper is concerned with the fatigue strength assessment of tendon porch found which is categorized as the special structural member in TLP. Large-scale tendon porch specimens have been designed and fabricated with API 2W Gr.50 steel recently produced by POSCO. Fatigue test has been carried out for three tendon porch specimens under various load level. Fatigue strength has been evaluated based on the nominal stress range and the results are compared with the fatigue design curve of DnV RP-C203. From the present experimental study, it has been found that the porch specimens satisfy the fatigue design rule although test was carried out under the positive stress ratio. It can be, therefore, said that the API 2W steel produced by POSCO possess sufficient fatigue strength.