• Journal of Ocean Engineering and Technology
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• v.18 no.6 s.61
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• pp.84-90
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• 2004

Fatigue tests were conducted on SM45C steel using hour-glass shaped smooth tubular specimen under biaxial loading in order to investigate the crack formation and growth at room temperature. Three types of loading systems, were employed fully-reserved cyclic torsion without a superimposed static tension or compression fully-reserved cyclic torsion with a superimposed static tension and fully-reserved cyclic torsion with a superimposed static compression. The test results showed that a superimposed static tensile mean stress reduced fatigue life however a superimposed static compressive mean stress increased fatigue life. Experimental results indicated that cracks were initiated on planes of maximum shear strain whether or not the mean stresses were superimposed. A biaxial mean stress had an effect on the direction that the cracks nucleated and propagated at stage 1 (mode II).

• Korean Journal of Community Nutrition
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• v.2 no.2
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• pp.169-178
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• 1997

Thin study measured dietary intakes in late pregnancy and psychological stress during the period of gestation and examined the roles of diet and psychological stress in pregnancy weight gain and infant birth weight. Study subjects were 98 pregnant women who delivered infants at 2 general hospitals in Taejon city. Mean weight gain during pregnancy was 14.6$\pm$4.89Kg. Mean infant birth weight was 3.39$\pm$0.62kg in males and 3.28$\pm$0.43Kg in females. Mean energy and protein intake levels were adequate, but mean iron and calcium intakes were only 61.2$\pm$14.9% and 79.1$\pm$18.2$\%$ of RDA, respectively. Fat intake which constitutes 22.0$\pm$4.3$\%$ of total energy intake, and animal protein intake which constitutes 22.0$\pm$4.3$\%$ of total energy intake, and animal protein intake which constitutes 53.7$\%$ of total protein intake were moderately high. Though mean energy, fat, animal protein, and meat protein intakes in the low psychological stress group were higher than those in the middle or high stress group, psychological stress did not significantly affect pregnancy weight gain and infant birth weight. High intakes of nutrients except for dairy protein, iron, and niacin were associated with higher pregnancy weight gain and high intakes of protein and meat protein were associated with higher infant birth weight. It is concluded that dietary intakes during pregnancy has effects on pregnancy weight gain and infant birth weight, and psychological stress has no direct effect on them.

• Journal of Oriental Neuropsychiatry
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• v.2 no.1
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• pp.51-69
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• 1991

This experiment was conducted to study anti-stress effects of Guibiondamtang on several measures of stress, which were number of lever pressing, weight changes, water intake and gastroduodenal ulcer. The following results were observed: 1. There were no significant differences between the control group and the sample group in total number of lever pressing. And no significant differences were observed in the shock duration and the shock length. 2. The median water intake during the stress was 25ml for the sample group and 17ml for the control group and the difference was not statistically significant. 3. The median body weight losess after the psychological stress was given were 28g for the sample group and 35g for the control group and the difference was not statistically significant. 4. The mean frequencies of gastric ulcers induced by the psychological stress were 0.3 for the sample group and 2.3 for the control group and the difference was statistically significant. 5. The mean lengths of gastric ulcers induced by the psychological stress were 0.3mm for the sample group and 2.8mm for the control group and the difference was statistically significant. 6. The mean ratings of gastric ulcers induced by the psychological stress were 0.7 for the sample group and 1.9 for the control group and the difference was stastically significant. Thus it may be concluded that Guibiondamtang has an antistress effect.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.7-16
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• 2010

Stress history increases the residual horizontal stress of granular soil and, consequently, the penetration resistance. This study analyzes the effect of stress history on the cone resistance ($q_c$), horizontal stress index ($K_D$) and dilatometer modulus ($E_D$) of CPT and DMT from calibration chamber specimen in OC as well as NC state. Test results show that the normalized cone resistance by mean effective stress correlates well with the relative density and the state parameter, whereas the normalized cone resistance by vertical effective stress is a little affected by stress history. The influence of stress history is more reflected on $K_D$ than $E_D$ and $q_c$. The $K_D/K_0$, in which the effect of stress history on $K_D$ is compensated by the at-rest coefficient of earth pressure, $K_0$, is related to relative density, state parameter and the normalized cone resistance by mean effective stress. It is also observed that the normalized dilatometer modulus by mean effective stress ($E_D/{\sigma}_m'$) shows a unique correlation with the state parameter, regardless of stress history.

• Journal of Korean Academy of Nursing
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• v.23 no.3
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• pp.431-452
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• 1993

This study was done to determine the effect of music therapy on stress and quality of life in patients undergoing hemodialysis. The research design was a nonequivalent control group pre -post test design. The subjects consisted of 21 patients who received hemodialysis in two hospitals located in Kwang Ju. The fourteen receiving treatment in one hospital were assigned to the experimental group and the seven in the other hospital to the control group. Data were gathered from December 14, 1992 to January 16, 1993 through questionnaires and physiological measurement. Data were analyzed by the SAS package using frequency, t-test, paired t-test and Pearson Prod uct - Moment Correlation Coefficient. The results of this study are summarized as follows ; 1. There were no significant differences between the two groups on stress scores and quality of life scores before the treatment. 2. The mean score on the psychological stress scale for the patients undergoing hemodialysis was 2.48 out of a maximum mean score of four, the items with high stress scores were “feeling of weakness and annoyed by everything”, “limitation of food”, “limitation of fluid”, “change in skin color” in that order. The psychological category showed the highest stress score followed by developmental, scoioeconomic and physiological stress categories in that order. 3. In the experimental group, post - test diastolic blood pressure decerased significantly(t=3.24, p=0.0064), but in the control group pre and post - test diastolic blood pressure were not different. 4. There was no difference between the two groups on the pre and post -test psychological stress scores or the depression scores. 5. The mean score of quality of life for patients undergoing hemodialysis was 2.75 out of a maxi-mum mean score of five. The category of ‘emtional state’ showed the highest score followed by ‘self - esteem’, ‘physical state and function’, ‘economic life’, ‘relationship with neighbors’ and ‘family relationship’ categories in that order. There was no significant difference in the pre and post - test quality of life scores between the two groups. 6. Hypothesis 1 that patients undergoing hemodialysis who received music therapy would have less stress than patients undergoing hemodialysis who did not receive music therapy is divided into two sub - hypotheses. 1) The first sub-hypothesis that patients undergoing hemodialysis who received music therapy would have less physiological stress than patients undergoing hemodialysis who did not receive music therapy was partly supported. Among three physiological stress indices (pulse, systolic blood pressure, diastolic blood pressure), only diastolic blood pressure decreased significantly after the treatment in the experimental group. 2) The second sub-hypothesis that patients undergoing hemodialysis who received music therapy would have less psychological stress than patients undergoing hemodialysis who did not receive music therapy was not supported. Psychological stress score and depression score were not significantly different before and after the treatment. 7. Hypothesis 2 that patients undergoing hemodialysis who received music therapy would have a higher quality of life score than patients undergoing. hemodialysis who did not received music therapy was not supported. There were no significant changes in the quality of life scores before and after the treatment.

• Journal of the Korean Statistical Society
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• v.18 no.2
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• pp.125-134
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• 1989

This paper presents optimum simple step-stress accelerated life test plans for the case where the test process is observed periodically at intervals of the same length. Two types of failure data, periodically observed complete data and periodically observed censored data, are considered. An exponential life distribution with a mean that is a log-linear function of stress, and a cumulative exposure model for the effect of changing stress are assumed. For each type of data, the optimum test plan which minimizes the asymptotic variance of the maximum likelihood estimator of the mean life at a design stress is obtained and its behaviors are studied.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1989.10a
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• pp.29-33
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• 1989

An extended model for the assessment of fatigue reliability of steel structures In the presence of residual stresses Is developed. The model explicitly Includes the uncertainties of the lean stress and residual stress in terms of the zero-mean equivalent stress-range. It Is assumed that the fatigue life of welded Joints follows the Weibull distribution. Based on the numerical illustrations, It Is shown that the probability of fatigue fat lure and the allowable stress-range for fatigue design could be significantly affected by the presence of residual stresses. This effect may be represented through the mean stress at the welded joints.

• Journal of the Korean Society of Safety
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• v.10 no.2
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• pp.120-128
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• 1995

The fatigue failure of rail is a principal source of derailment accidents. The reduction of fatigue failures can be achieved by Intensive track maintenance and periodic safety assessments for the railway. For the safety assessments, it is required to have more accurate knowledge for fatigue behavior such as the crack initiation, propagation, crack growth rate and the remaining service life in rail. In this paper, the mean stress effects for the fatigue behavior of rail steel are studied. For this study, the fatigue test is conducted and some equations for fatigue evaluation are applied and compared. From the results, we can see that the fatigue crack growth rate is the more increased as the men stress Is the more increased, the mean stress effect is represented well by the combination of stress intensity factor range and maximum stress intensity factor and Crooker and Range's equation represented by ${\Delta}K, K_{max}$ is the best fit for fatigue evaluation and safety assessment of rail.

• Journal of computational fluids engineering
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• v.16 no.4
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• pp.28-38
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• 2011

Large eddy simulation(LES) of fully developed turbulent pipe flow has been performed to investigate the effect of Reynolds number on the flow field at $Re_{\tau}$=180, 395, 590 based on friction velocity and pipe radius. A dynamic subgrid-scale model for the turbulent subgrid-scale stresses was employed to close the governing equations. The mean flow properties, mean velocity profiles and turbulent intensities obtained from the present LES are in good agreement with the previous numerical and experimental results currently available. The Reynolds number effects were observed in the mean velocity profile, root-mean-square of velocity fluctuations, Reynolds shear stress and turbulent viscosity.

• The Journal of Korean Academic Society of Nursing Education
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• v.25 no.1
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• pp.125-135
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• 2019

Purpose: This study was conducted to determine the mediator effect of social support in the association between stress for college life and depression among nursing students. Methods: The participants of the study were 201 university students in A and C cities. Self-report questionnaires were used to measure the variables. In the data analysis, the SPSSWIN 25.0 program was utilized for descriptive statistics, Pearson's correlation, Sobel test and multiple regression analysis. Results: Mean scores of stress for college life, depression and social support were 2.56, 4.12 and 0.61, respectively. Stress for college life and depression showed a significant positive correlation (r=.60, p<.001), while depression and social support showed a significant negative correlation (r=-.46, p<.001). Lastly, stress for college life and social support showed a significant negative correlation (r=-.55, p<.001). The analysis of the mediator effect of social support in the association between stress for college life and depression showed that social support had a significant mediator effect. Conclusion: Among nursing students, social support may be a mediator in the association between stress for college life and depression. Therefore, strategies for nursing intervention to improve social support should be developed for nursing students.