• 대한금속재료학회지
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• 제46권7호
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• pp.412-419
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• 2008

Creep behavior of the squeeze infiltrated AS52 Mg matrix composites reinforced with 15 vol% of aluminum borate whiskers($Al_{18}B_4O_{33}w$) fabricated squeeze infiltration method was investigated. Microstructure of the composites was observed as uniformly distributed reinforcement in the matrix without any particular defects of casting pores etc.. Creep test was carried out at the temperature of 150 and $200^{\circ}C$ under the applied stress range of 60~120 MPa. The creep resistance of the composite was significantly improved comparing with the unreinforced AS52 Mg alloy. The creep behavior of composites might be interpreted with the substructure invariant model successfully for the composite. Threshold stress of the composite exist for the creep deformation of the composite. The analysis of the creep behavior of the composite with threshold stress indicated that creep deformation was controlled by the lattice diffusion process of AS52 Mg matrix at given effective stresses and temperatures. Activation energy was also calculated to check lattice diffusion controlled creep behavior of the composite.

• 가정과삶의질연구
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• 제23권4호
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• pp.27-34
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• 2005

The purpose of this study was to identify the patterns of coping with marital conflict and child-rearing stress among mothers of young children. The participants were 166 mothers of children who were between 3 years and 7 years of age, living in the North Kyongsang Province. Paired t-test, ANOVA, Scheffe' test, Pearson's correlation and partial correlation analyses were conducted for this study. The results of this study were as follows. (1) In those situations where the participants experienced marital conflict and child-rearing stress, they were more likely to use an avoidance coping strategy than an approach coping strategy. (2) Among the mothers who were experiencing marital conflict or child-rearing stress, the group that suffered a higher level of stress was more likely to employ an avoidance coping strategy. However, there were no differences in the approach coping behavior by the level of stress. (3) When the level of marital conflict and child-rearing stress were controlled, approach coping behavior with marital conflict was still moderately correlated with approach coping behavior with child-rearing stress.

• 대한간호학회지
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• 제34권2호
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• pp.213-224
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• 2004

Purpose: This study was aimed to evaluate the effect of progressive muscle relaxation training using biofeedback on perceived stress, stress response, immune response and climacteric symptoms, Method: This was a crossover, pre-post test design, The study subjects are 36 middle-aged women who were selected at 2 public health centers, The independent variable was Biofeedback training for 4 weeks, twice a week and home training for 4 weeks, Dependent variables were perceived stress, stress response, immune response, and climacteric symptoms measured with Hildtch's scale (1996), Result: Progressive muscle relaxation training using biofeedback was not effective in reducing perceived stress, but it was shown to be effective in reducing physiological stress responses such as pulse rate and EMG, Though blood pressure and skin conductance were repeatedly down, and skin temperature slowly increased, there were no statistically significant differences. Progressive muscle relaxation training using biofeedback was not effective in reducing serum cortisol, enhancing immune responses, or decreasing climacteric symptoms. Conclusion: The findings point to a pressing need for further, well-controlled and designed research with consideration in selection of subjects and instruments, frequency of measurements, the sampling method, and intervention modalities.

• BMB Reports
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• 제31권2호
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• pp.201-208
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• 1998

Amino acid analogs, like other inducers of stress response, induce the synthesis of stress proteins in mammalian cells. In this study, Drosophila Kc cells, in which translation is tightly controlled during stress response, was treated with proline analogs, L-azetidine-2-carboxylic acid (AzC) and 3,4-dehydro-L-proline (dh-P). Kc cells exposed to AzC or dh-P induced the synthesis of several proteins which had the same molecular weights as known heat shock proteins. However, in Kc cells, normal protein synthesis still continued in the presence of amino acids analogs unlike in heat-shocked cells. For the induction of stress response, the incorporation of dh-P into the protein was not essential, but the incorporation of AzC was. The stress protein synthesis was regulated mainly at the transcriptional level by AzC, whereas it was regulated by dh-P at the transcription level and possibly posttranscription level. During recovery, the stress protein synthesis stopped sooner in analog-treated cells than in heat-shocked cells even though the accumulated amount of Hsp70 was much less in proline analogstreated cells. It could be concluded that the proline analogs, AzC and dh-P, induced stress response through a different mechanism from heat shock.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.133-141
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• 2006

The Low cycle fatigue behavior of 11.7Cr-1.1Mo heat-resisting steel has been investigated under strain-controlled conditions with mean stresses at room temperature and $300^{\circ}C$. For the tensile mean stress test, the initial high tensile mean stress generally relaxed to zero at room temperature, however, at $300^{\circ}C$ initial tensile mean stress relaxed to compressive mean stress. Low cycle fatigue lives under mean stress conditions are usually correlated using modifications to the strain-life approach. Based on the fatigue test results from different stain ratio of -1, 0, 0.5, and 0.75 at room temperature and $300^{\circ}C$, the fatigue damage of the steel was represented by using cyclic strain energy density. Total strain energy density considering mean stress indicated well better than not considering mean stress at $300^{\circ}C$. Predicted fatigue life using Smith-Watson-Topper's parameter correlated fairly well with the experimental life at $300^{\circ}C$.

• 가정∙방문간호학회지
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• 제17권2호
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• pp.127-134
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• 2010

Purpose: This study was done to identify the effects of stress management program on perceived stress, geriatric depression, and somatic symptom in elderly Korean subjects. Methods: A pre-post test design with a nonequivalent control group was used. Fifty elderly Korean subjects with mild depression were recruited from the registerants at four public senior citizen centers within S-gu in Seoul. They were randomly allotted to the experimental group(n=25) and control group(n=25). The intervention was performed for one hour each week at each center for 5 weeks. The effects were measured by Perceived Stress Scale, Geriatric Depression Scale-Korean, and Patient Health Questionnaire-15. Results: Perceived stress and depression were significantly reduced in experimental group. The somatic symptom was not significantly different in the experimental group. Conclusion: The stress management program may have merit in improving mental health of elderly Koreans, although this conclusion is equivocal pending further well-controlled studies that include mediation techniques such as conversion therapy and health gymnastics.

• 대한간호학회지
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• 제16권2호
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• pp.36-43
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• 1986

The main purpose of this study was to explore the effect of the stress of hospitalization on the sleep pattern. Additionaly, this study was also to demonstrate how Johnson's nursing model may be applied to as nursing process. 104 hospitalized patients on surgical and medical wards were asked to rate 49 stress producing events associated with experience of hospitalization and sleep pattern scale. Five university hospitals were used as the setting for this study. Data for the study were collected by patient interview during hospitalization, self-reports and review of charts. For the analysis of the data, the pearson's correlation analysis of covariance and regression analysis were used. The results of this study were stated as follows; 1. The mean of the hospital stress scores was 111.261(S.D.=26.160). This means that the level of the hospitalization stress is high. The mean of the sleep pattern scores was 12.204(S.D. =2.615) This means that the characteristic's of the sleep pattern is poor. 2. The relationship between the hospitalization stress and sleep pattern was statistically significant at .01 level. 3. The effect of the hospitalization stress influenced strongly on the sleep pattern after sex, trait anxiety as covariates controlled. 4. The hospitalization stress revealed a 12% pre-diction as an influenced factor for the sleep pattern. Therefore, It can he said that the hospital stress did contribute significantly to the characteristics of the sleep pattern. Johnson's model can he also said that it is useful for the the assessment and diagnosis in nursing process.

• 농업과학연구
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• 제46권3호
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• pp.637-643
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• 2019

The aim of the present study was to evaluate the effect of the induced heat stress on physiological response and serum biochemical parameters involving glucose, cholesterol, blood urea nitrogen (BUN), non-esterified fatty acids (NEFA), and cortisol in Holstein calves. Ten calves were kept in a climate controlled room (air temperature $37^{\circ}C$ and 90% humidity from 09:00 to 19:00) for three days. Those animals were given a one-day adaptation period. During the treatment period, we measured the skin temperature six times. Following the treatment periods, blood samples were collected before the experiment began (09:00) and at the end of the stress period (19:00). To aid analysis of the biochemical parameters, also we monitored the rectal temperature. The results, exhibited that both rectal and skin temperature showed increase in the heat stress-induced animals as compared with unstressed animals. Moreover, we noticed that the levels of BUN and NEFA increased in the blood serum of heat stress induced animals when compared with un-stressed ones. From these results, we concluded that the physiological and biochemical changes in the calves were induced by heat stress. Hence, the present study findings could be employed as base line data for development of stress reduction techniques in the dairy industry.

• Korea-Australia Rheology Journal
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• 제12권3_4호
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• pp.151-155
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• 2000

A semiconducting poly(naphthalene quinone) radical (PNQR) was synthesized from Friedel-Craft acylation between naphthalene and phthalic anhydride and used as dispersing particles of a dry-base electrorheological (ER) material in silicone oil. Under an applied electric field (E), the dynamic yield stress (${\tau}_{dyn}$) of this ER fluid, obtained from a steady shear experiment with a controlled shear rate mode, was observed to increase with $E^{1.45}$ Based on this relationship, we propose a universal correlation curve for shear viscosity, which is independent of E using a scaling analysis.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.69-72
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• 1997

The indentation process in the Vickers hardness test is a kind of controlled local plastic deformation. Vickers hardness is defined as indenting force per unit area indented by a pyramid-shaped diamond at the hardness test. That is a measure of mechanical resistance against indentation of a rigid body into the deformable material. Therefore it is well known that Vickers hardness has a direct relation with the flow stress of the strain-hardened tmaterial. This relation is theoretically investigated and the result is given for use in practice.