• Elastomers and Composites
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• 제45권4호
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• pp.250-255
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• 2010

비뉴톤 점탄성 Maxwell 요소와 탄성 스프링으로 이루어진 3 요소 비뉴톤 모델로부터 응력완화 식을 유도하였다. 이 식을 응력완화 실험 결과에 적용하여 여러 가지 모델 파라메타를 계산하였다. 모델 파라메타로부터 계산한 이론 곡선은 실험적인 응력완화 곡선과 잘 일치하였다. 비선형 점탄성 모델 파라메타로부터 섬유고분자 물질의 홀부피, 미세구조, 점탄성성질, 역학적인 성질 등을 연구하였다. 응력완화 실험은 용매기를 부착한 인장 시험기를 사용하였으며, 시료는 두 종류의 polyacrylonitrile-polyvinylchloride 공중합체와 또 다른 두 종류의 PVC 모노 필라멘트 섬유를 여러 온도의 공기와 물속에서 응력완화 실험을 하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.424-429
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• 2001

Residual stresses can be produced during manufacturing processes, eg. welding, machining and plastic working, and also in service. It can be superimposed with externally applied loads, so that unexpected deformations and failures of members will be occurred. Especially, the strength and the life of welded components are affected extensively by the residual stresses distributed around their weldments not only under static loads, but also fatigue loads. These residual stresses are not kept constant, but relaxed or redistributed during service. Under static loads the relaxation takes place when the residual stress superimposed with external stress exceeds locally the yield stress of material used. It is shown that under fatigue loads the residual stress is considerably relieved by the first or few cycle loading, and then gradually relaxed with increasing loading cycles. Although many investigations in this field have been carried out, the phenomenon and mechanism of the stress relaxation by mechanical means are still not clear, and there are few comprehensive models for predicting specific effects on the stress relaxation. In this study, the effects of applied static and fatigue loads on the residual stress relaxation were Investigated, and a model to predict quantitatively the residual stress relaxation was proposed.

• Journal of Korean Biological Nursing Science
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• 제12권1호
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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.

• Journal of Welding and Joining
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• 제20권3호
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• pp.84-90
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• 2002

The strength and the life of welded components are affected extensively by the residual stresses distributed around their weldments not only under static loads, but also fatigue loads. The residual stress can be superimposed with externally applied loads, so that unexpected deformations and failures of members will be occurred. These residual stresses are not kept constant, but relaxed or redistributed during in service. Under static loads the relaxation takes place when the external stress superimposed with the residual stress exceeds locally the yield stress of material used. It is shown that under fatigue loads the residual stress is considerably relieved by the first or flew cycle loading, and then gradually relaxed with increasing loading cycles. In this study the phenomenon and mechanism of the stress relaxation by mechanical means were investigated and a model to predict quantitatively the residual stress relaxation for the case of static and fatigue loading condition was proposed.

• 한국지반신소재학회논문집
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• 제5권3호
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• pp.31-36
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• 2006

본 연구에서는 보호, 여과, 차수기능을 갖는 부직포 지오텍스타일과 지오멤브레인의 응력완화거동을 각각 고찰하였다. "두 가지 지오신세틱스 제품의 응력완화거동을 해석하는데 "전이현상이론"이 적용되었다. 이들 지오신세틱스 제품의 응력완화거동에서 초기 및 후기 완화시간은 구성방정식으로부터 구하였다. 이들 지오신세틱스 제품의 초기완화거동은 부가변형률에 대한 의존성이 있으며, 특히 온도가 증가 할수록 증가하였다. 끝으로, 이들 지오신세틱스 제품의 초기 및 후기 완화시간은 부가변형률 및 온도가 커질수록 짧아졌으며, 완화시간 감소는 지오멤브레인보다 부직포 지오텍스타일의 경우가 더 큼을 알 수 있었다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 춘계학술발표대회 논문집
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• pp.76-79
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• 2000

Polymeric composites exhibit highly nonlinear and rate dependent behavior during loading and unloading in off-axis directions. The equilibrium state of stress during loading is lower than the state of stress produced at finite strain rates. The amount of stress relaxation during loading decreases. Interestingly, however, the stress goes up to reach to the equilibrium state of stress for a fixed displacement during unloading. The unloading behavior is quite similar to the loading behavior. The stress relaxation patterns during loading and unloading is also similar, and those depend on the fiber orientation angles and the loading and unloading rates. The AS4/PEEK thermoplastic composite is used to characterize the relaxation behavior for different off-axis angles and loading rates. There exists a transient loading region at the beginning of unloading. The effective stress and effective plastic strain concept is used to establish a master curve of stress recovery pattern for different off-axis angles and unloading rates.

• 대한간호학회지
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• 제27권2호
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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.

• 정신신체의학
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• 제9권1호
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• pp.93-102
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• 2001

이완반응은 갚은 휴식상태를 말하며, 소위 스트레스반응으로 불리는 투쟁-도피 반응의 생리적 변화와 반대되는 생리적 변화를 일으키게 된다. 따라서 인위적으로 이완반응을 일으킴으로써 이러한 스트레스 반응을 상쇄시킬 수 있다. 이러한 이완반응을 일으킬 수 있는 복식호흡, 명상, 점진적 근육이완기법, 자율이완훈련, 생체되먹이기법 등의 다양한 이완기법들이 제시되어 왔으며, 이들은 다양한 신체, 정신 질환뿐만 아니라 정상적인 스트레스 관리 프로그램에 있어서도 마음과 신체의 안녕을 위해 유익한 도움을 줄 수 있음이 알려져 있다. 이러한 이완기법들은 스트레스 관리를 위한 전체적 과정의 한 부분으로 이해되어야 할 것이며, 자신에 맞는 적절한 기법을 찾아 지속적인 훈련을 함으로써 효과적인 스트레스 관리 방법으로서의 역할을 할 수 있을 것이다. 이에 본 저자는 명상, 점진적 근육이완기법, 자율이완훈련 및 기타 이완기법에 대한 보다 구체적이고 실제적인 방법을 제시하고자 한다. 스트레스와 관련된 다양한 신체, 정신 질환들에 대한 치료적 접근을 함에 있어서, 전통적 치료 방법에 병합하여 이완기법을 사용함으로써 스트레스와 질병 사이의 조절자로 이용할 수 있을 것이다.

• 대한기계학회논문집A
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• 제26권10호
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• pp.2018-2025
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• 2002

It is well known that the strength and the fatigue life of welded steel components are affected extensively by welding residual stresses distributed around their weldments under not only monotonic but also cyclic loads. The externally applied loads are to be superimposed with the welding residual stresses, so that unexpected deformations and failures of the components might occur. These residual stresses are not kept constant, but relaxed or redistributed during in service. Under monotonic loads the relaxation takes place when the sum of external and welding residual stress exceeds locally the yield stress of material used. By the way, it is shown that under cyclic loads the welding residual stress is considerably relieved by the first or the early cycles of loads, and then gradually relaxed with increasing loading cycles. Although many investigations in this field have been carried out, the phenomenon and mechanism of the stress relaxation are still not clear, and there are few comprehensive models to predict amount of relaxed welding residual stress. In this study, the characteristics of the welding residual stress relaxation under monotonic and cyclic loads were investigated, and a model to predict quantitatively amount of welding residual stress relaxation was proposed.

• Journal of Preventive Medicine and Public Health
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• 제43권5호
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• pp.445-450
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• 2010

Objectives: Emotional support and a stress management program should be simultaneously provided to clients as effective preventive services for healthy behavioral change. This study was conducted to review various relaxation and meditation intervention methods and their applicability for a preventive service program. Methods and results: The author of this paper tried to find various relaxation and meditation programs through a literature review and program searching and to introduce them. The 'Relaxation Response' and 'Mindfulness Based Stress Reduction (MBSR)' are the most the widely used meditative programs in mainstream medical systems. Abdominal breathing, Progressive Musclular Relaxation (PMR), Relaxative Imagery, Autogenic Training (AT) and Biofeedback are other well-known techniques for relaxation and stress management. I have developed and implemented some programs using these methods. Relaxation and meditation classes for cancer patients and a meditation based stress coping workshop are examples of this program. Conclusions: Relaxation and meditation seem to be good and effective methods for primary, secondary and tertiary preventive service programs. Program development and standardization and further study are needed for more and wider use of the mindbody approach in the preventive service area of medicine.