• Journal of Welding and Joining
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• 제2권1호
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• pp.49-57
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• 1984

The influence of weld defect, residual stress and microstructure on the Low Cycle Fatigue(L. C. F.) behaviour of AISI 304L austenitic stainless steel weldment has been studied. The specimens were welded by shielded metal are welding process, post weld heat treated(PWHT) at 900.deg.C for 1.5hrs, and tested under total strain controlled condition at room temperature. The results of the experiment showed that weld defect affected the L.C.F. behaviour of weldment deleteriously compared to the residual stress or microstructure, and it reduced the L.C.F. life about 70-80%. The PWHT exhibited beneficial effect on the L.C.F. behaviour and increased the L.C.F. life about 120%. This enhancement by PWHT was attributed to the removal of residual stress and recovery of weld metal ductility. The cyclic stress flow of as welded specimens showed intermediate cyclic softening, whereas those of heat treated specimens showed continuous cyclic hardening, and this difference was explained in terms of the residual stress removal and dislocation behaviour. Scanning electron microscopy studies of fatigue fracture surface showed that weld defects of large size and near weld surface were detrimental to the L.C.F. behaviour of weldment.

• 소성∙가공
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• 제17권8호
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• pp.558-563
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• 2008

The initial strain, the applied stress exponent, the activation energy, and rupture time in AZ31 magnesium alloy have been measured in order to predict the deformation mechanism and rupture life of creep over the temperature range of 423-443K. Creep tests were carried out under constant applied stress and temperature, and the lever type tester and automatic temperature controller was used for it, respectively. The experimental results showed that the applied stress exponent was about 9.74, and the activation energy for creep, 113.6KJ/mol was less than that of the self diffusion of Mg alloy including aluminum. From the results, the mechanism for creep deformation seems to be controlled by cross slip at the temperature range of 423-443K. Also the higher the applied stress and temperature, the higher the initial strain. And the rupture time for creep decreased as quadratic function with increasing the initial strain in double logarithmic axis.

• Nuclear Engineering and Technology
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• 제47권5호
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• pp.633-645
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• 2015

In order to analyze the mechanical properties of two-way different configurations of prestressed concrete members subjected to axial loading, a finite element model based on the nuclear power plant containments is demonstrated. This model takes into account the influences of different principal stress directions, the uniaxial or biaxial loading, and biaxial loading ratio. The displacement-controlled load is applied to obtain the stress estrain response. The simulated results indicate that the differences of principal stress axes have great effects on the stress-strain response under uniaxial loading. When the specimens are subjected to biaxial loading, the change trend of stress with the increase of loading ratio is obviously different along different layout directions. In addition, correlation experiments and finite element analyses were conducted to verify the validity and reliability of the analysis in this study.

• 한국환경복원기술학회지
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• 제1권1호
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• pp.54-62
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• 1998

This study measured the shearing resistance of the roots of the Sasamorpha purpurascens, Miscanthus sinensis, Lespedeza cyrtobotrya by the tensile strength gained through their individual tensile test for the Root Reinforcement Model. The results to have measured this stress by experiment are as follows. 1) The mean root diameter of the Lespedeza cyrtobotrya used for this experiment was 2.19mm and the mean tensile stress was calculated as $929.489kgf/cm^2$. As for the Sasamorpha purpurascens, its mean root diameter was 1.727mm, and the mean tensile stress was $292.069kgf/cm^2$. And as for the Miscanthus sinensis, its mean root diameter was 0.814mm, and the mean tensile stress was $696.947kgf/cm^2$. And so, it was grasped that Lespedeza cyrtobotrya was highest in tensile stress. 2) ${\Delta}Cr(kg/cm^2)$ of the shearing resistance calculated by estimating the areal ratio of roots at $10^{-3}$ is $1.069kg/cm^2$ in Lespedeza cyrtobotrya, $0.336kg/cm^2$ in Sasamorpha purpurascens, and $0.801kg/cm^2$ in Miscanthus sinensis. That is, Lespedeza cyrtobotrya has the highest shearing resistance. However, since a precise analysis of the controlled factors of the slope analyses are demanded for more accurate dynamic analyses, the future demands a study on this.

• Physical Therapy Rehabilitation Science
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• 제10권2호
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• pp.141-146
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• 2021

Objective: This study was at investigated the effects of manual lymphatic drainage (MLD) on stress and pain in patients with postoperative breast cancer. Design: A randomized controlled trial. Methods: A total of twenty-two patients with postoperative breast cancer voluntarily participated in the study. Subjects were randomly assigned to the MLD groups (n=12) and rest groups (n=12). The intervention was conducted in each group for twenty minutes a day, five times a week, for four weeks. Before and after the intervention, the participants measured sympathetic nerve, parasympathetic nerve, and pain by using a sphygmograph and short-form McGill pain questionnaire.An independent t-test was used to analyze pretest and posttest changes between the groups, a paired t-test was used to analyze pre-posttests within each group. Results: After analyzing, the MLD group has been shown a significant decrease in the sympathetic nervous system (p<0.05), a significant increase in the parasympathetic nervous system (p<0.05), and a significant increase in pain (p<0.05). However, the rest group was no significant difference between pre and post. Conclusions: The results of this study confirmed that MLD techniques are an effective method in reducing stress and pain in patients with postoperativebreast cancer. And it is thought that can be used as basic data and to develop programs on stress and pain management reduction for patients with breast cancer.

• 한국융합학회논문지
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• 제11권2호
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• pp.361-373
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• 2020

본 연구의 목적은 국내에서 혈액투석환자를 대상으로 적용된 스트레스 중재프로그램을 메타분석하여 스트레스 중재프로그램의 효과를 확인하고, 스트레스 중재 방법의 특성과 경향을 파악하기 위함이다. 분석대상연구는 총 10편으로 MINORS를 사용하여 문헌의 질평가를 실시하였으며, Comprehen sive Meta Analysis Version 3.0 및 Review manager version 5.3을 활용하여 자료를 분석하였다. 연구의 질 평가 점수는 21.2점이었으며, 중재프로그램의 심리적 스트레스에 대한 효과크기는 -.72, 생리적 스트레스 중 코티졸의 효과크기는 -.52로 보통의 효과를 보였다. 하위그룹 분석에서 음악요법, 아로마요법, 투석 중 중재, 개인중재, 1회당 60분 이상의 중재, 총 10~20회기 중재의 효과가 더 컸다. 본 연구 결과를 활용하여 추후 효과적인 스트레스 중재프로그램을 구성할 수 있을 것이며, 추후 혈액투석환자를 대상으로 한 무작위배정 실험연구가 더 필요하다.

• 한국재료학회지
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• 제25권11호
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• pp.630-635
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• 2015

The fatigue strength of a nickel-base superalloy was studied. Stress-controlled fatigue tests were carried out at $700^{\circ}C$ and 5 Hz using triangular wave forms. In this study, two kinds of testing procedures were adopted. One is the conventional tension-zero fatigue test(R = 0). The other was a procedure in which the maximum stress was held at 1000 MPa and the minimum stress was diverse from zero to 1000 MPa at 24 and $700^{\circ}C$. The results of the fatigue tests at $700^{\circ}C$ indicate that the fracture mechanism changed according to both the mean stress and the stress range. At a higher stress range, ${\gamma}^{\prime}$ precipitates are sheared by a/2<110> dislocation pairs coupled by APB. Therefore, in a large stress range, the deformation occurred by shearing of ${\gamma}^{\prime}$ by a/2<110> dislocations, which brought about crystallographic shear fracture. As the stress range was decreased, the fracture mode gradually changed from crystallographic shear fracture to gradual growth of fatigue cracks. At an intermediate stress range, as it became more difficult for a/2<110> dislocation pairs to shear ${\gamma}^{\prime}$ particles, cracks started to propagate in the matrix, avoiding the harder ${\gamma}^{\prime}$ particles. High mean stress induced creep deformation, that is, ${\gamma}^{\prime}$ particles were sheared by {111}<112> slip systems, which led to the formation of stacking faults in the precipitates. Thus, the change in fracture mechanism brought about the inversion of the S-N curves.

• Restorative Dentistry and Endodontics
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• 제37권2호
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• pp.79-83
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• 2012

Objectives: The purpose of this study was to evaluate the relation between intentionally induced internal stress and cyclic fatigue failure of .06 taper ProFile. Materials and Methods: Length 25 mm, .06 taper ProFile (Dentsply Maillefer), and size 20, 25, 30, 35 and 40 were used in this study. To give the internal stress, the rotary NiTi files were put into the .02 taper, Endo-Training-Bloc (Dentsply Maillefer) until auto-stop by torque controlled motor. Rotary NiTi files were grouped by the number of induced internal stress and randomly distributed among one control group and three experimental groups (n = 10, Stress 0 [control], Stress 1, Stress 2 and Stress 3). For cyclic fatigue measurement, time for separation of the rotary NiTi files was recorded. The fractured surfaces were observed by field emission scanning electron microscope (FE-SEM, SU-70, Hitachi). The time for separation was statistically analyzed using two-way ANOVA and post-hoc Scheffe test at 95% level. Results: In .06 taper ProFile size 20, 25, 30, 35 and 40, there were statistically significant difference on time for separation between control group and the other groups (p < 0.05). Conclusion: In the limitation of this study, cyclic fatigue failure of .06 taper ProFile is influenced by internal stress accumulated in the files.

• Journal of Korean Biological Nursing Science
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• 제23권4호
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• pp.267-275
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• 2021

Purpose: The purpose of this study was to evaluate the effects of inhaled clary sage (Salvia sclarea L.) oil or linalyl acetate on patients' anxiety and stress levels before undergoing chemotherapy. Methods: Forty-five eligible participants were randomly assigned to inhale clary sage oil, or linalyl acetate, each at concentrations of 5% vol/vol in almond oil or pure almond oil (control). State-trait anxiety inventory (STAI), Stress rating scale, anxiety-visual analog scale (Anxiety-VAS), stress-visual analog scale (Stress-VAS), blood pressure, and heart rate were measured before and after the inhalation prior to undergoing chemotherapy. Results: Anxiety-VAS and Stress-VAS were significantly lower after than before inhalation of clary sage oil (p< .01 and p< .05, respectively) and linalyl acetate (p< .05 and p< .05, respectively), despite having no significant difference in the three groups compared with control group. Systolic (p< .05) and diastolic (p< .01) blood pressure before undergoing chemotherapy were significantly lower after than before inhalation of linalyl acetate, while there was no significant difference in after than before inhalation of clary sage oil, despite both reducing levels of anxiety and stress. Conclusion: These findings suggest that linalyl acetate inhalation may be inappropriate in lowering anxiety and stress in patients undergoing chemotherapy, despite its anxiolytic and antistress effects, while clary sage oil inhalation may be useful in reducing anxiety and stress in patients undergoing chemotherapy, which has a risk of hypotensive side effects.

• Journal of Ginseng Research
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• 제47권6호
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• pp.766-772
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• 2023

Background: Korean Red Ginseng (KRG) is an effective anti-stress treatment. In this study, we investigated the therapeutic potential effects of KRG on relieving stress in a general population using transcriptome analysis. Methods: We conducted an 8-week clinical pilot study on 90 healthy men who reported stress. The study was completed by 43 participants in the KRG group and 44 participants in the placebo group. Participants were randomized 1:1 to the KRG and placebo groups. We evaluated the stress by stress response inventory (SRI) at baseline and 8 weeks. The main outcomes were changes in the levels of neurotransmitters (NTs) and NT-related gene expression. NTs were analyzed using automated (GC) content, and levels of gene expression were measured by reads per kilobase of transcript per million mapped reads (RPKM). Results: The KRG group showed significantly preserved epinephrine decrease compared with placebo group at 8 weeks (changes in epinephrine, KRG vs. placebo; -1623.2 ± 46101.5 vs. -35116.3 ± 86288.2, p = 0012). Among subjects who higher SRI score, meaning stress increased compared to baseline, the KRG group showed a smaller decrease in serotonin than the placebo group (changes in serotonin, KRG vs. placebo; -2627.5 ± 5859.1 vs, -8087.4 ± 7162.4, p = 0.005) and a smaller increase in cortisol than the placebo group (changes in cortisol, KRG vs. placebo; 1912.7 ± 10097.75 vs. 8046.2 ± 8050.6 , p = 0.019) in subgroup analysis. Transcriptome findings indicated that KRG intake affects gene expression related with metabolism of choline, adrenalin, and monoamine. Conclusion: These findings suggest that KRG has beneficial effects on the amelioration of stress response in NTs, and this effect is more prominent in stressful situations. Further clinical studies are required to confirm the anti-stress effect of KRG.