• Proceedings of the KSME Conference
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• 2000.04a
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• pp.19-24
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• 2000

Stress corrosion crack growth is simulated after assuming a small axial surface crack inside a S/G tube. Internal pressure and residual stresses are considered as applied forces. Stress intensity factors along crack front, variation of crack shape and crack growth rate are obtained and discussed. It is noticed that the aspect ratio of the crack is not depend on the initial crack shape but depend on the residual stress distribution.

• Steel and Composite Structures
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• v.51 no.2
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• pp.103-116
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• 2024

Based on the consistent couple stress theory (CCST), we develop a unified formulation for analyzing the static bending and free vibration behaviors of functionally graded (FG) microscale beams (MBs). The strong forms of the CCST-based Euler-Bernoulli, Timoshenko, and Reddy beam theories, as well as the CCST-based sinusoidal, exponential, and hyperbolic shear deformation beam theories, can be obtained by assigning some specific shape functions of the shear deformations varying through the thickness direction of the FGMBs in the unified formulation. The above theories are thus included as special cases of the unified CCST. A comparative study between the results obtained using a variety of CCST-based beam theories and those obtained using their modified couple stress theory-based counterparts is carried out. The impacts of some essential factors on the deformation, stress, and natural frequency parameters of the FGMBs are examined, including the material length-scale parameter, the aspect ratio, and the material-property gradient index.

• Journal of Korean Academy of Nursing
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• v.5 no.2
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• pp.29-37
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• 1975

The purpose of this study was to measure the extent of stress existing in hospitalized patients which might play an important part in delaying recovery of patients. The study was conducted July l0th through 16th, 1975; a total of 146 patients from 2 general hospitals in Seoul were sampled. Questionnaire, formulated by the researcher, were used to gather necessary information concerning stress in accordance with the physical, psychological, economical and social variables. Data were analysed by mean stress score, and the significances were tested by Critical Ratio. The results were as follows ; 1. No significant difference was revealed in accordance with sex, however, male patients showed higher stress scores on the economic variables. 2. No. significant difference was apparent in accordance with marital status, however, the unmarried showed a tendency of higher stress scores at all variables. 3. Significant difference was revealed between the age group of 35-49 years and that of over 50 years; the age group of 18-34, and 35-49 years showed higher stress scores. 4. No. significant difference was revealed in accordance with previous experience of hospitalization, however, the group with previous experience tends to show higher stress scores in all variables. 5. No significant difference was revealed in accordance with the types of admission, however, group admitted on emergency showed higher stress scores compared to the group admitted plained in advance at social and economic variables. 6. No significant difference was revealed in accordance with the length of hospitalization, however, tendencies were apparent that the longer the length of hospitalization, the lower the mean stress scores.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.278-288
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• 1998

An efficient and useful method to improve the local stress field in a displacement-formulated finite element solution has been proposed using the theory of conjugate approximations for a stress field and the Loubignac's iterative method for a displacement field. Validity of the proposed method has been tested through three test examples, to improve the stress field and displacement field in the whole domain and the local regions. As a result of analysis on the test examples, it is found that the stress field in the local regions are approximated to those in the whole domain within a few iterations which have satisfied the original finite element equilibrium equation. In addition, it is found that the local stress field are by far better approximated to the exact stress field than the displacement-based stress field with the reduction of the finite-element mesh-size.

• Journal of Korean Biological Nursing Science
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• v.14 no.4
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• pp.249-257
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• 2012

Purpose: The purpose of this study was to examine the effects of phytoncide aromatherapy on stress, symptoms of stress and heart rate variability among nursing students. Methods: This study is a randomized control-group non-synchronized design. The experimental group (n=31) underwent phytoncide aromatherapy for 2 weeks, while the control group (n=31) received placebo therapy. The data were collected using self-administration questionnaires and measurement of heart rate variability (HRV) and analyzed using SPSS WIN 18.0 program. A p value <.05 was considered statistically significant. Results: Total score of stress, individual score of intrapersonal stress, and score of peripheral manifestations in symptoms of stress in the experimental group were significantly lower than those of the control group. All indices of HRV were significantly different between the two groups. LF norm and LF/HF ratio in the experimental group were significantly lower than those of the control group, and HF norm in the experimental group was significantly higher than that of in the control group. Conclusion: Based on these results, it can be suggested that phytoncide aromatherapy was effective in decreasing stress and peripheral manifestations of stress and changing in HRV among nursing students.

• Korean Journal of Adult Nursing
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• v.19 no.1
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• pp.1-11
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• 2007

Purpose: To identify the effects of the aromatherapy on stress of nurses working in operating room. Methods: The study design was nonequivalent control-group pretest-posttest design. The subjects were 45 nurses working in the operating room. Experimental group were 24 nurses in G Hospital and control group were 21 nurses in U Hospital. All of the subjects were measured of the subjective stress, stress responses and the job stress. For aromatherapy, lavender, bergamot, and ylang were mixed in the ratio of 2 : 2 : 1. Results: 1) "The subjective stress of experimental group is lower than that of the control group" was supported (t=-2.70, p=.01). 2) "The stress responses of experi-mental group is lower than that of the control group" was supported (t=-2.49, p=.01). 3) "The job stress of experimental group is lower than that of the control group" was supported (t=-7.97, p=.00). Conclusion: This study suggested that such aroma inhalation method could be effective on stress of nurses working in operating room.

• Korean Journal of Poultry Science
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• v.47 no.1
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• pp.29-37
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• 2020

This study was performed to investigate the effect of mixed rearing of male and female chickens on the stress response in Korean native chickens. To identify the degree of the stress response, heterophil-lymphocyte ratio (H/L ratio), heat shock protein genes (HSPs) expression, and intracellular nuclear DNA damage rate were analyzed before and after the mixed rearing of male and female chickens. The results showed that the H/L ratio of chickens after mixing males and females was more than thrice as higher than before mixing (P<0.001), but the differences between males and females were not significant. HSP-70, HSP90-α, and HSP90-β expression levels were 2.5 to 3.4 times higher after mixing male and female chickens, compared to before mixing (P<0.01). In the mixed rearing of male and female chickens, the increase in HSPs expression in females was higher than in males. Comet indicators in intracellular DNA damage rate analysis showed a significant increase after mixing male and female chickens compared to before mixing (P<0.001). However, there was no significant difference between males and females with respect to DNA damage rate. Taken together, these results suggest that male and female mixed rearing acts as a strong external stressor in both male and female chickens.

• Journal of the Korean Geotechnical Society
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• v.22 no.2
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• pp.5-17
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• 2006

In order to investigate the stabilizing effect of nails against sliding, a series of model tests were carried out. The apparatus of model test was designed to perform the model test of soil slope reinforced by nails. The instrumentation system was used to measure the deflection behavior of nails during slope failure. As a result of model tests, the quantity and the occurred position of the maximum bending stress are changed according to the area ratio and the inclination angles of nails. The maximum stabilizing effect against sliding of nails is presented at 0.7$\%$ of the area ratio because the biggest maximum bending stress occurs at this time. But, the stabilizing effect of nails decreases with more than 0.7$\%$ of the area ratio. In the same condition of the area ratio, the stabilizing effect of nails is excellent at -10$^{circ}$ of the inclination angles of nails. The sliding surface can be predicted on the basis of the position of the maximum bending stress in each nails. The shape and depth of sliding surface are changed according to the area ratio and the inclination angles of nails.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.2
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• pp.252-256
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• 2007

This study was carried out to determine the effect of vitamin E and vitamin C on the performance of Japanese quails (Coturnix coturnix japonica) reared under heat stress during the growth and egg production period. A total of 810 seven-day-old Japanese quails were used in the trial. The birds received a diet with either three levels of vitamin E (DL-${\alpha}$Tocopheryl acetate) (60, 120 and 240 mg/kg of diet) and vitamin C (ROVIMIX STAY-C 35) (60, 120 and 240 mg/kg of diet). Live weight on day 35 and weight gain were the lowest in the group of chicks on a combination of 60 mg of vitamin E and 60 mg of vitamin C, whereas the highest live weight was demonstrated in chicks on a combination of 240 mg of vitamin E and 240 mg of vitamin C (p<0.01). The effects of treatments on cumulative feed consumption, feed conversion ratio, age at 5% lay, sexual maturity weight, rate of lay and mean egg weight values were found to be significant (p<0.01). The highest feed consumption, feed conversion ratio, age at 5% lay, sexual maturity weight, rate of lay and mean egg weight values were found in the group on a combination of 240 mg of vitamin E and 240 mg of vitamin C. The effect of treatments on the mortality ratio was found to be insignificant (p>0.01). The cost of supplementing diets with vitamin E and vitamin C is very low. Therefore such a combination of supplement can offer a potential protective management practice in preventing heat stress related losses in performance of Japanese quails.

• Journal of the Korean Institute of Gas
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• v.15 no.5
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• pp.37-41
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• 2011

This paper presents the strength safety of a hydrogen gas composite fuel tank, which is analyzed using a FEM based on the criterion of US DOT-CFFC and Korean Standard. A hydrogen gas composite tank in which is fabricated by an aluminum liner of 6061-T6 material and carbon fiber wound composite layers of T800-24K is charged with a filling pressure of 70MPa and a gas storage capacity of 130 liter. The FEM results indicated that von Mises stress, 255.2MPa of an aluminum liner inner tank is low compared with that of 95% yield strength, 272MPa. And a carbon fiber stress ratio of a composite fuel tank is 3.11 in hoop direction and 3.04 in helical direction. These data indicate that a carbon fiber gas tank is safe in comparison to that of a recommended criterion of 2.4 stress ratio. Thus, the proposed composite tank with 130 liter capacity and 70MPa filling pressure is usable in strength safety.