• Title, Summary, Keyword: Stress Relaxation Test

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Rheological Properties of Acorn Flour Gels by Stress Relaxation Test (응력완화 검사(stress relaxation test)에 의한 도토리묵의 물리적 특성)

  • 김영아;이혜수
    • Korean journal of food and cookery science
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    • v.1 no.1
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    • pp.53-56
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    • 1985
  • The rheological models of acorn flour gels with different concentrations were investigated by stress relaxation test. The analysis of relaxation curves by successive residual method revealed that the rheological behavior of acorn flour gels could be expressed by the 7-element, generalized Maxwell model. The equilibrium modulus and modulus of elasticity increased by the increment of acorn flour concentration.

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The Effects of Relaxation on Stress and Blood Pressure Induced by Cognitive Distress Game among College Students (대학생에게 적용한 이완요법이 인지압박게임으로 인해 유발된 스트레스와 혈압에 미치는 영향)

  • Song, Mi-Ryeong;Kim, Sung-Hee
    • Journal of Korean Biological Nursing Science
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    • v.12 no.1
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    • pp.8-15
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    • 2010
  • Purpose: The purpose of this study is to investigate the effects of relaxation on stress and blood pressure of the college students induced by a cognitive distress game. Methods: The subjects for this research were 18 individuals whose stress index scores were below 4.0 (Asan city). The 18 subjects were divided into two, 9 students were assigned to the experimental group and the other 9 students to the control group randomly. Survey was used to gather data to recognize general characteristics and the level of stress and blood pressure were measured before and after cognitive distress game and relaxation. The gathered data were analyzed with frequency, $X^2$-test, Wilcoxon signed ranks test and Mann Whitney U test using SPSS 14.0 program. Results: Both level of stress and blood pressure displayed a statistically significant difference pre and post cognitive distress game. Relaxation had a statistically significant effect on level of stress. Relaxation, however, did not have statistically significant effect on blood pressure. Conclusion: The above results suggest that while relaxation was effective in reducing level of stress for college students, and therefore recommendable as a means to deal with stress. However, to investigate the effects on physiological index such as blood pressure, further research is needed.

Stress Relaxation Test of Granite under Water-Saturated Triaxial Condition (화강암의 응력완화현상에 관한 수침삼축시험)

  • 서용석
    • The Journal of Engineering Geology
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    • v.10 no.3
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    • pp.217-223
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    • 2000
  • Microcracks that consist of quarry planes of granite are an essential factor affecting the long-term behavior of granite. In this paper, fine-grained granite distributed in the Tsukuba area of Japan was selected and microcracks were measured by using scanline method. In addition, a new relaxation testing equipment was developed to carry out stress relaxation test under water-saturated triaxial condition. Based on the relaxation test results with the initial stress level of 75%, the axial stress is decreased by 39%-49% just after the start of the tests, and the totally relaxed stress is 10∼24 MPa in 190 ERT (Elapsed relaxation time, hour). In addition, the relaxed stress is increased with the density of cracks which are parallel to axial load direction.

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A Study on the Mathematical Modeling of Human Pharyngeal Tissue Viscoelasticity (인두조직의 점 탄성특성의 수학적모델링에 관한 연구)

  • 김성민;김남현
    • Journal of Biomedical Engineering Research
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    • v.19 no.5
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    • pp.495-502
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    • 1998
  • A mathematical model of viscoelasticity on the material property of human pharyngeal tissue utilizing Y.C. Fung's Quasi-linear viscoelastic theory is proposed based on cyclic load, stress relaxation, incremental load, and uniaxial tensile load tests. The material properties are characterized and compared with other biological materials' results. The mathematical model is proposed by combining two characteristic functions determined from the stress relaxation and uniaxial tensile load tests. The reduced stress relaxation function G(t) and elastic response function S(t) are obtained from stress relaxation test and uniaxial tensile load test results respectively. Then the model describing stress-time history of the tissue is implemented utilizing two functions. The proposed model is evaluated and validated by comparing the model's cyclic behaviour with experimental results. The model data could be utilized as an important information for constructing 3-dimensional biomechanical model of human pharynx using FEM(Finite Element Method).

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Evaluation of Internal Stress and Dislocation Velocity in Creep with 25Cr-20Ni Stainless Steels (25Cr-20Ni계 스테인리스강의 크리프 변형중 내부응력과 운동전위밀도의 평가)

  • Park, In-Duck;Ahn, Seok-Hwan;Nam, Ki-Woo
    • Proceedings of the KSME Conference
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    • pp.296-301
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    • 2004
  • By the purpose to investigate the change of internal stress and mobile dislocation density in creep, the stress relaxation test is carried out in the condition of each strain. Mobile dislocation density increased until it reached minimum creep rate and after that, it decreased and internal stress didn't have the change approximately until it reached minimum creep rate and after that, it decreased. The stress relaxation rate is fast and approached zero after 1.5 seconds after the beginning of the stress relaxation. And the larger the applied stress is, the larger the internal stress is. By the evaluation of mobility of dislocation, the dislocations glide viscously in STS31OJlTB but it is the dislocations glide viscously which N passes by cutting Cr atom rather than typical viscosity movement after calculating mobility of dislocation.

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Evaluation of Internal Stress and Dislocation Velocity in Creep with Austenite Stainless Steels (오스테나이트계 스테인리스강의 크리프 변형중 내부응력과 운동전위밀도의 평가)

  • Kim Hyun Soo;Nam Ki Woo;Park In Duck
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.2
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    • pp.214-219
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    • 2005
  • To investigate the change of internal stress and mobile dislocation density in the creep, stress relaxation test was examined from each strain range. Mobile dislocation density increased until it reached minimum creep rate but after that, it decreased. Internal stress did not change until it reached minimum creep rate but after that, it decreased. The stress relaxation rate is fast and approached zero later 1.5 seconds, which were begun in the stress relaxation. When the applied stress is large, the internal stress is large. It is cleared that dislocations glide viscously which N passes by cutting Cr atom rather than typical viscosity movement by the evaluation of mobility of dislocation in STS310J1TB.

The Effect of Progressive Muscle Relaxation using Biofeedback on Stress Response and Natural Killer Cell in first Clinical Practice of Nursing Students (바이오휘드백을 이용한 점진적 근육이완훈련이 스트레스반응과 면역반응에 미치는 효과)

  • Kim Keum-Soon
    • Journal of Korean Academy of Fundamentals of Nursing
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    • v.7 no.1
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    • pp.109-121
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    • 2000
  • Increasingly nursing science is embracing the concepts and methodology derived from psycho-neuroimmunology. It has been previously shown that stress increases and immune function declines in students undergoing examinations. To date, however, no many studies have been reported on stress levels, immune function and interventions in Korean students undergoing their first clinical nursing rotation. It was proposed that nursing students during their first clinical rotation experience increase in stress because of the novelty of the situation and their lack of clinical knowledge. It was also hypothesized that biofeedback and progressive relaxation, methods of self-regulation of involuntary autonomic nervous system responses, would reduce the stress response. The purpose of this study is to test the effectiveness of progressive muscle laxation using biofeedback The effectiveness of the experimental methods was tested by measuring the degree of symptoms of stress (SOS) and the values of ephinephrine, pulse rate, blood pressure and natural killer cells. The subjects of this study were thirty nursing students divided into two groups: experimental group was progressive muscle relaxation group using biofeedback and control group. This study was conducted for 8 weeks of clinical practice. Biofeedback training was done by software developed by J&J company (1-410 form for progressive muscle training). Progressive muscle relaxation training according to Jacobson's Theory was done by messaged word from biofeedback. The data was analyzed using Chronbach' ${\alpha}$ and t-test of the SPSS program and the significance level of statistics was 5%. The results of the study were : 1) The progressive muscle relaxation training using biofeedback was effective for the reduction of symptoms of stress(t=-4.248, p<.001) under clinical practice stress conditions. 2) The progressive muscle relaxation training using biofeedback was not effective for the values of epinephrine(t=-1.294, p=.206). 3) The progressive muscle relaxation training using biofeedback was effective for the reduction of systolic blood pressure (t=-2.757, p=.01). 4) The progressive muscle relaxation training using biofeedback was effective for the reduction of diastolic blood pressure (p=-2.032, 0=.05). 5) The progressive muscle relaxation training using biofeedback was not effective for the reduction of pulse rate(t=-15, p=.988). 6) The progressive muscle relaxation training using biofeedback was effective for the maintenance of natural killer cells (t=2.381, p=02). The first clinical rotation for student nurses is a stressful experience as seen by the rise in the SOS in the control group. Biofeedback using progressive muscle relaxation were effective in preventing the rise of symptoms of stress and the blood pressure means when comparing the pre to post clinical experience, The mean natural killer cell count was depressed in the control group but not significantly different in the experimental groups, It is proposed here that stress via the hypothalamic - pituitary - adrenal axis suppressed the NK cell count whereas the relaxation methods prevented the rise in stress and the resulting immune depression. We recommend relaxation techniques using biofeedback as a health promotion technique to reduce psychological stress. In summary. the progressive muscle relaxation training using biofeedback was effective for the reduction of symptoms of stress under clinical practice stress conditions.

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Stress Relaxation Properties of Cucumber under Bending Moment (휨 모멘트에 대한 오이의 응력이완(應力弛緩) 특성(特性))

  • Song, C.H.;Kim, M.S.;Park, J.M.
    • Journal of Biosystems Engineering
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    • v.18 no.3
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    • pp.262-269
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    • 1993
  • Stress relaxation behaviors of the cucumber under bending moment were tested with UTM at three levels of loading rate and initial deflection ratio. Sample cucumber was selected from three cultivars of cucumber, Cheongjangmadi, Baekdadagi, and Gyeousalicheongjang, because these cultivars are the most popular grown cultivars in Korea. When the bending moment was applied to the cucumber sample, the effective span between simple supports was held a constant value of 116mm with consideration of the selected sample length. The objectives of this study were to develop the rheological models such as linear and nonlinear models of the stress relaxation for the cucumber samples, and to investigate the effects of loading rate and initial deflection ratio on the stress relaxation behavior of the cucumber. The results of this study may be summarized as follows : 1. Stress relaxation behavior of the cucumber could be well described by the generalized Maxwell model for each level of deflection ratio. But the stress relaxation behavior of the sample was found to be initial deflection ratio and time dependent, and it was represented the nonlinear viscoelastic model as a function of initial deflection ratio and time. 2. Stress relaxation behavior of the cucumber samples was very highly affected by the loading rate and the initial deflection ratio. The more loading rate and initial deflection ratio resulted in the more initial bending stress and after stress relaxation progressed more rapidly. 3. At the same test conditions, it was found that the stress relaxation rate of Cheongjangmadi was faster than that of other cultivars.

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Effect of an Integrated Stress Management Program on the Stress Symptoms of Psychophysiological Patients (통합적 스트레스 관리 프로그램이 정신생리질환자의 스트레스증상에 미치는 영향 -소화성 궤양 환자를 중심으로-)

  • 한금선
    • Journal of Korean Academy of Nursing
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    • v.27 no.2
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    • pp.289-302
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    • 1997
  • The main purpose of this study was to identify the effects of integrated stress management program on the stress symptoms of psychophysiological patients. especially patients with peptic ulcer. The study employed a quasi-experimental design using two different experimental groups. The samples in the integrated stress management program participated in autogenic training with biofeedback. discussions on effective coping method. cognitive. behavioral, and emotional management. They were also provided with an educational booklet on stress management and an tape on progressive muscie relaxation. Each session lasted one hour and the program consisted of seven sessions over four weeks. The other group was only given an tape on progressive muscle relaxation. The data were collected from May 20 to september 25, 1996. A total 47 patients from one university hospital located in Seoul participated, experiment group 1(integrated stress management training) had 23 subjects and experiment group 2(progressive muscle relaxation training) had 24 subjects. The effects of these programs were measured by the stress symptom scale developed by Kogan(1991) which was translated by Lee(1992) and the healing status of the ulcer evaluated by a physician. The data were analyzed using Chi-square test, t- test, ANOVA, repeated measure ANOVA. The result are as follows : 1. The integrated stress management group reported a significantly lower stress symptom score than the group given the progressive muscle relaxation only. 2. The integrated stress management group showed a significantly improved ulcer status as compared to the group given a progressive muscle relaxation only. In conclusion, it was found that the integrated stress management program was more effective in decreasing self-reported stress and physiological symptoms among patients with peptic ulcer as compared to the progressive muscle relaxation group. Based on this finding, the following suggestions can be made. 1. It is necessary to broaden the scope of nursing practice for psychophysiological patients so nurses can include stress management as part of patient care. 2. It is necessary to develop stress management program for other patients whose symptoms are known to be related to stress. 3. It is necessary to replicated this study with a larger sample in different settings.

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The Evaluation and Relaxation of Residual Stress of Steel Cord (Steel Cord 선재의 판류응력 평가 및 완화에 관한 연구)

  • Lee, S.K.;Hwang, W.H.;Kim, B.M.;Bae, C.M.;Lee, C.Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.191-194
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    • 2006
  • Recently the quality improvement of the steel cord product is demanded by the tire market. After wire drawing process, produced residual stresses have a harmful effect on the durability of the wire and become the cause which decreases the quality of the product. Therefore, to improve the quality of the steel cord product, the research regarding the method of residual stress relaxation is necessary. To evaluate the quality of the drawn wire, it is important to measure the residual stress, because the residual stress decides a variety of the quality level which is demanded in the drawn wire. This study proposed a residual stress relaxation method in the drawn wire using FE analysis. The validity of the analysis results was verified by nanoindentation test.

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