• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1862-1870
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• 2020

The purpose of this study is to investigate the effect of welding residual stress on operating stress in designing a nuclear turbine welded rotor. A two-dimensional axisymmetric finite element model is employed to calculate the residual stress before and after post weld heat treatment (PWHT), and then the superposition of residual stress after PWHT and operating stress at normal speed and overspeed were discussed. The investigated results show that operating stress can be affected significantly by welding residual stress, and the distribution trend of superposition stress at the weld area is mainly determined by welding residual stress. The superposition of residual stress and operating stress is linear superposition, and the hoop stress distribution of superposition stress is similar with the distribution of residual stress. With the increasing overspeed, the distribution pattern of the hoop superimposed stress remains almost unchanged, while the stress level increases.

• Journal of Society of Preventive Korean Medicine
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• v.13 no.2
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• pp.27-38
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• 2009

Objective : This study was to examine a relationship among subjective psychological stress, physical stress response and oxidative stress. Methods : The subjects were consisted of 87 healthy volunteers. To assess subjective psychological stress, SRI(stress response inventory) was completed. To assess psychological and physical stress response, HRV(Heart Rate Variability) were tested. To assess oxidative stress, d-roms(Derivatives of reactive oxygen metabolites test) test was conducted. Subjects were divided into 3 groups depending on SRI(Stress Response Inventory) score, low stress response(LSR: lower than 30 percentile), Medium(MSR: 30-70 percentile) and high stress response(HSR: higher than 70 percentile). The Relationship between Stress Response and Oxidative Stress was estimated by correlation and One-way ANOVA analysis. Results : There were no significant differences of demographic data among 3 groups. There was a significant difference of oxidative stress among 3 groups. Conclusion : Our results suggest that there is a weak positive correlation between subjective psychological stress and oxidative stress. There is a significant difference of oxidative stress between HSR group and LSR group.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.5
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• pp.467-476
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• 2016

In the present study, we examined the effect of pertussis toxin (PTX) administered centrally in a variety of stress-induced blood glucose level. Mice were exposed to stress after the pretreatment of PTX (0.05 or 0.1 mg) i.c.v. or i.t. once for 6 days. Blood glucose level was measured at 0, 30, 60 and 120 min after stress stimulation. The blood glucose level was increased in all stress groups. The blood glucose level reached at maximum level after 30 min of stress stimulation and returned to a normal level after 2 h of stress stimulation in restraint stress, physical, and emotional stress groups. The blood glucose level induced by cold-water swimming stress was gradually increased up to 1 h and returned to the normal level. The intracerebroventricular (i.c.v.) or intrathecal (i.t.) pretreatment with PTX, a $G_i$ inhibitor, alone produced a hypoglycemia and almost abolished the elevation of the blood level induced by stress stimulation. The central pretreatment with PTX caused a reduction of plasma insulin level, whereas plasma corticosterone level was further up-regulated in all stress models. Our results suggest that the hyperglycemia produced by physical stress, emotional stress, restraint stress, and the cold-water swimming stress appear to be mediated by activation of centrally located PTX-sensitive G proteins. The reduction of blood glucose level by PTX appears to due to the reduction of plasma insulin level. The reduction of blood glucose level by PTX was accompanied by the reduction of plasma insulin level. Plasma corticosterone level up-regulation by PTX in stress models may be due to a blood glucose homeostatic mechanism.

• Human Ecology Research
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• v.57 no.2
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• pp.295-305
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• 2019

This study examined the effects of social comparison orientation and stress coping styles on job-seeking stress experienced by university students. The participants of this study were 324 junior and senior students (151 males and 173 females) from six universities located in Seoul who were preparing for employment. They were asked to respond to a written questionnaire to measure research variables for the Job-Seeking Stress Scale, the Social Comparison Orientation Scale, and the Ways of Coping Checklist. The data were analyzed by means of descriptive statistics and a hierarchical multiple regression. The major findings of this study were as follows. First, social comparison orientation had a positive effect on job-seeking stress of university students, revealing that students with a high level of social comparison orientation were more likely to experience job-seeking stress. Second, both emotion-alleviation coping style and wishful thinking coping style increased level of job-seeking stress. In addition, problem-focused coping style had a negative influence on job-seeking stress, whereas social support seeking coping style had no significant effect on it. The results suggested that it would be possible to reduce job-seeking stress of university students by changing either social comparison or stress coping style.

• Biomolecules & Therapeutics
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• v.12 no.4
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• pp.242-249
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• 2004

The main aim of this study was to investigate stress related activities of Sun-ginseng extract as a candidate for anti-stress-related functional supplement by comparing its effect to those of red ginseng, which is also known to alleviate stress. Normal group was not exposed to stress while the control group was exposed to stress. Rats were orally administered once a day with 200 mg red ginseng (RG) extract, 100 or 200 mg Sun-ginseng (SG) extract/kg body weight. Mice were given water containing 400 mg red ginseng extract, 200 or 400 mg SG/100 mL potable water. Rats were given supplements for 5 days without stress, and 5 days with restraint and electroshock stress. After final stress, stress-related behavioral changes of experimental animals were recorded and levels of blood corticosterone were measured. Mice were given supplements for 5 days through drinking water, and then fatigue related motor activity were recorded. SG-supplementation partially blocked stress effect on locomotion and elevated plus maze test in rats, and also partially blocked stress-induced behavioral changes such as freezing, burrowing, smelling, facewashing, grooming and rearing behavior in rats. SG-supplementation decreased blood corticosterone level which is increased by stress in rats. Effects of SG may not be modulated by GABAnergic nervous system. SG-supplementation prolonged swimming time and staying time on the wire and rotarod wheel in mice. These results suggest that SG partially protects living organisms from stress attack in some cases and thus has the potential to be used as a functional food to alleviate stress response.

• Geomechanics and Engineering
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• v.16 no.2
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• pp.113-124
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• 2018

Under repeated loading, the residual stresses within the subgrade and subsoil can accelerate the deformation of the road structures. In this paper, a series of laboratory cyclic loading model tests and small-scale model tests were conducted to investigate the dynamic stress response within soils under different loading conditions. The experimental results showed that a dynamic stress accumulation effect occurred if the soil showed cumulative deformation: (1) the residual stress increased and accumulated with an increasing number of loading cycles, and (2) the residual stress was superimposed on the stress response of the subsequent loading cycles, inducing a greater peak stress response. There are two conditions that must be met for the dynamic stress accumulation effect to occur. A threshold state exists only if the external load exceeds the cyclic threshold stress. Then, the stress accumulation effect occurs. A higher loading frequency results in a higher rate of increase for the residual stress. In addition to the superposition of the increasing residual stress, soil densification might contribute to the increasing peak stress during cyclic loading. An increase in soil stiffness and a decrease in dissipative energy induce a greater stress transmission within the material.

• Journal of Korean Biological Nursing Science
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• v.21 no.3
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• pp.178-187
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• 2019

Purpose: The purpose of this study was to investigate how college students' perceived stress, cognitive stress, and somatization affect their heart rate variability (HRV). Methods: This study is a cross-sectional survey research on 191 university students, registered at the G University. The perceived stress scale (PSS) and cognitive stress response scale, were used to assess level of stress. The somatization symptom scale of the Symptom Check List 90 (SCL-90), was used to assess level of somatization caused by stress. To assess heart rate variability (HRV), we conducted a five-minute test using a pulse wave analyzer, to analyze short-term HRV. Results: The SCL-90 somatization score had relatively high positive correlation (p< .001) with cognitive stress, but low positive correlation (p< .001) with perceived stress. Cognitive stress response had low negative correlation (p< .001) with 1nSDNN and 1nRMSSD among HRV parameters. Perceived stress was not correlated with HRV. Multiple regression analysis showed that variables of perceived stress, cognitive stress, and somatization symptoms, could not explain HRV. By contrast, one of the HRV indicators, 1nSDNN, was affected by age, gender, and aggressive-hostile thought, the latter being a subscale of the cognitive stress response scale. Conclusion: This study suggests that stress evaluation for people in early adulthood will be more effective, if the evaluation examines cognitive stress and heart rate variability.

• The Journal of Korean Obstetrics and Gynecology
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• v.18 no.4
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• pp.85-105
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• 2005

Purpose : Investigate the effects of Chungganhaewooltang(CHT) on immobilization-stress or cold-stress in C576BL/6J mice. Methods : Male C57BL/6J 30 mice of weighting 18${\pm}$2g, were divided into sixs groups including the immobilization-stress group(5heads), after immobilization-stress CHT oral administration(500mg/kg) groups(5heads), cold-stress group(5heads) and after cold-stress CHT oral administration(500mg/kg) groups(5heads). then we observed changes in the serum histamine and corticosterone level and changes immune system Results : Immobilization-stress or cold-stress increased the serum level of histamine and corticosterone. CHT decreased the serum level of histamine and corticosterone increased by cold-stress. CHT inhibited the release of histamine from mast cells at the concentration of 0.1 mg/ml. In addition, immobilization-stress or cold-stress decreased the cell viability of murine thymocytes and splenocytes. CHT increased the cell viability of thymocytes decreased by immobilization-stress or cold-stress, but did not affect the cell viability of splenocytes decreased by immobilization-stress or cold-stress. Also immobilization-stress or cold-stress increased DNA fragmentation of thymocytes and splenocytes. CHT decreased DNA fragmentation of thymocytes increased by immobilization-stress or cold-stress, but did not affect DNA fragmentation of splenocytes increased by immobilization-stress or cold-stress. Immobilization-stress increased the population of thymic $CD4^+$ cells. CHT decreased the population of thymic $CD4^+$ cells increased by immobolization-stress. Immobilization-stress or cold-stress decreased the population of $B220^+$ cells and increased the population of $thy1^+$ cells. CHT decreased the population of $thy1^+$ cells increased by immobilization-stress or cold-stress. Immobilization-stress or cold-stress increased the population of splenic $CD4^+$ cells and $CD8^+$ cells. CHT decreased the population of splenic $CD4^+$ cells increased by immobolization-stress or cold-stress. Immobilization-stress or cold-stress decreased the production of ${\gamma}-interferon$(IFN) interleukin(IL)-2 and IL-4. CHT enhanced the production of ${\gamma}-IFN$ decreased by immobilization-stress or cold-stress but did not affect the production of IL-2 and IL-4 decreased by immobilization-stress or cold-stress. Furthermore, Immobilization- stress or cold-stress decreased the phagocytic activity of peritoneal macrophages and the production of nitric oxide. CHT enhanced the phagocytic activity and nitric oxide production decreased by cold-stress. Conclusion : CHT may be useful for the prevention and treatment of stress via suppression of serum histamine and corticosterone level and enhancement of immune response.

• The Journal of Korean Obstetrics and Gynecology
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• v.19 no.4
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• pp.93-116
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• 2006

Purpose : This study is to examine the effects of Hwaganjeon water extract(HGJ) on immobilization-stress or cold-stress in BALB/C mice. Methods : We have Hwaganjeon water extract(HGJ) by freeze-dryer & melt it by a saline solution. We feed HGJ 500mg/Kg to 5mice, and add immobilization-stress by putting mice in plastic cylinder 10 hours, and add cold-stress by putting mice in $4^{\circ}C$ cold room 6 hours. Results : 1. HGJ decreased the serum level of histamine and corticosterone increased by immobilization-stress or cold-stress. HGJ inhibited the release of histamine from mast cells at the concentration of 1 mg/ml. 2. HGJ did not affect the cell viability of thymocytes decreased by immobilization-stress or cold-stress, but increased the cell viability of splenocytes decreased by immobilization-stress or cold-stress. 3. HGJ decreased the population of splenic $CD4^{+}$ and $CD8^{+}$cells increased by immobolization-stress or cold-stress. 4. HGJ enhanced the production of ${\gamma}$-interferon(IFN) and interleukin(IL)-2 decreased by immobilization-stress or cold-stress. Conclusion : These results indicate that HGJ may be useful for the prevention and treatment of stress via suppression of serum histamine and corticosterone level and enhancement of immune response.

• YAKHAK HOEJI
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• v.49 no.4
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• pp.291-298
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• 2005

Gardenia Jasminoides(GJ) is traditionally used for treatment of hepatic disease, insomnia, anxiety, and inflammatory disease. The aim of this study is to examine effects of GJ extract in response to stress. Animals of the normal group were not exposed to any stress and the control group were exposed to stress. The rats of the Ginseng and GJ supplementary group were orally administered once a day with 100mg of red ginseng extract, 100mg of GJ extract/kg body weight. The mice were given water containing 200mg of red ginseng extract, 200mg of GJ extract/100ml potable water. Animals were given supplements for 7 days without stress, and then were given supplements for 5 days with restraint and electroshock stress. After loading final stress, we examined stress related behavioral changes of experimental animals and measured the levels of blood corticosterone. GJ-supplementation partially blocked the stress effect on locomotion and elevated plus maze test in rats, and also partially blocked stress-induced behavioral changes such as freezing, burrowing, face-washing, smelling and rearing behavior in rats. The effect was almost equipotent to Ginseng's effect. GJ-supplementation didn't influence on fatigue related behavior or physical stress resistance. GJ-supplementation decreased the levels of blood corticosterone which is increased by stress in rats. These results suggest that GJ protects partially the living organism from stress attack and it has the potential to be used as a functional material to alleviate stress response.