• Composites Research
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• 제30권6호
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• pp.406-409
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• 2017

The thin-walled cylindrical tubes are frequently used for the evaluation of fatigue property of composites. But the curvature of the tubular specimen induces interlaminar normal stress which may affect the fatigue property. In this paper interlaminar normal stress effect on the fatigue behaviour of thin-walled graphite/epoxy tubes $[{\pm}45]_s$ composites was studied experimentally. It was concluded that the interlaminar normal stress induced by the curvature of the cylinder has no discernible effect on the fatigue life. But excessive internal pressure can produce the stiffness increase and this affects the fatigue life of the cylindrical tubular composite.

• 터널과지하공간
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• 제17권3호
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• pp.186-196
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• 2007

본 연구에서는 거칠기와 수직응력이 절리면의 전단거동에 미치는 영향을 검토하기 위하여 30개의 자연암반 절리 시료를 대상으로 실험을 실시하였다. 3차원 레이저 거칠기 측정장치를 이용하여 절리면의 거칠기 정보를 측정하였으며, 시료들의 거칠기에 따라 10개씩 세 가지 그룹으로 분류하였다. 다음으로 수직응력을 다섯 단계로 변화시켜가며 전단실험을 실시함으로써 최대전단강도, 잔류전단강도, 전단강성, 팽창특성 등을 조사하였다. 절리면의 거칠기가 증가함에 따라 최대전단강도는 증가하였으며, 거칠기가 최대전단강도에 미치는 영향은 수직응력이 작은 경우에 더욱 크게 나타났다. 또한 절리면의 거칠기가 증가할수록 잔류전단강도도 점차 증가하였다. 전단강성은 거칠기 및 수직응력이 커짐에 따라 증가하는 것으로 나타났으나, 팽창각은 수직응력이 증가할수록 감소하였고, 동일한 수직응력하에서는 절리면의 거칠기가 커질수록 증가하였다.

• 영재교육연구
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• 제22권4호
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• pp.841-853
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• 2012

본 연구는 초등 영재학생과 일반학생의 학업스트레스에 미치는 자기효능감과 스트레스 대처방식의 상호작용 효과를 검증하고자 하였다. 6학년 영재학생 100명과 일반학생 100명을 대상으로 연구한 결과, 영재학생이 일반학생보다 문제중심 대처방식을 많이 사용하였으나, 학업스트레스, 학업적 자기효능감 및 정서중심 대처방식에는 유의한 차이가 없었다. 영재학생과 일반학생의 학업스트레스는 학업적 자기효능감이 높을수록, 문제중심 대처방식을 많이 사용할수록 감소되었으며, 학업적 자기효능감과 문제중심 대처방식의 상호작용에 영향을 받았다. 상호작용효과를 살펴보면, 영재학생의 학업적 자기효능감이 학업스트레스를 감소시키는 효과는 문제중심 대처방식의 수준이 높을수록 커졌으며, 일반학생은 문제중심 대처방식의 수준이 높을 때에만 학업적 자기효능감이 유의하게 학업스트레스를 감소시키는 것으로 나타났다.

• 대한간호학회지
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• 제25권4호
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• pp.668-680
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• 1995

The purpose of this study was to contribute to family nursing for reducing stress and improving coping of the parents of mentally retarded children. Data were collected through self-reported questionnaires during a period of 2 months between November 1994 and January 1995 in the Kyoung-in area. The subjects consist of 180 parents (90 mothers and 90 fathers) of mentally retarded children attending schools for the handicapped and 186 parents (93 mothers and 93 fathers) of normal children. The levels of general stress and of parental role stress were measured with the General stress scale and the Parental role stress scale, respectively, while the Coping scale was adopted to measure the level of coping. The data were analyzed by using Chi-square test. fisher's exact test, Repeated masured ANOVA, oneway ANOVA and Scheffe comparison test. The results were as follows ; 1. The level of general stress was significantly higher in the mothers and the fathers of the men-tally retarded than in the respective parents of the normal. Of the parents, the mothers experienced significantly greater level of general stress than the fathers did in both groups of the retarded and of the normal. 2. As for the parental role stress, the mothers and the fathers of the mentally retarded experienced significantly greater stress than respective parents of normal children did. In particular, the stress was significantly higher in the mothers than the fathers of these children in both groups. The difference in the levels of parental role stress experienced by mothers and by fathers was significantly bigger among those of the mentally retarded tnan among those of normal children. 3. No significant difference in the level of coping was observed between the mothers of both groups and the fathers of both groups. By contrast, the fathers revealed significantly greater scores in coping than the mothers in both groups. 4. General stress experienced by the fathers of the mentally retarded was different by health status, satisfaction with spouses, and the supports from their spouses. Health status, satisfaction with spouses, and monthly income Influenced parental role stress experienced by those fathers. Their level of coping was associated with their satis-faction with spouses and family life. 5. Of the mothers of the mentally retarded, the level of general stress was different by their health status, while parental role stress was related to the satisfaction with their spouses and the child's age. The level of coping among the mothers was different by the supports from their spouses. The above findings indicate that those parents of the mentally retarded did not take more coping strategies than those of the normal did, despite greater stress experienced among themselves. Hence, nursing intervention for managing stress should be given to those parents including fathers of mentally retarded children. Mothers of the mentally retarded, in particular, should receive high priority in planning nursing care, since they experience greater levels of both general stress and parental role stress than their spouses, which is most likey due to primary responsibility in child rearing given to them at home.

• Coupled systems mechanics
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• 제8권6호
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• pp.501-522
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• 2019

The present study is concerned with the thermoelastic interactions in a two dimensional axisymmetric problem in transversely isotropic thermoelastic solid using new modified couple stress theory without energy dissipation and with two temperatures. The Laplace and Hankel transforms have been employed to find the general solution to the field equations. Concentrated normal force, normal force over the circular region, concentrated thermal source and thermal source over the circular region have been taken to illustrate the application of the approach. The components of displacements, stress, couple stress and conductive temperature distribution are obtained in the transformed domain. The resulting quantities are obtained in the physical domain by using numerical inversion technique. The effect of two temperature varying by taking different values for the two temperature on the components of normal stress, tangential stress, conductive temperature and couple stress are depicted graphically.

• 터널과지하공간
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• 제13권3호
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• pp.169-179
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• 2003

암석의 절리면 전단강도의 이방성을 연구하기 위하여 인공절리면을 형성한 시편에 대한 실험을 실시하고 그 결과를 분석하였다. 즉 낮은 수직응력 상태에서 전단 방향에 따른 전단강도, 전단강성 및 마찰각을 구하기 위한 실험을 실시하였다 그 결과 낮은 수직응력하에서 전단 강도 및 강성은 전단 방향에 따라 이방성을 보이며, 특히 수직응력 2.45 MPa미만에서 뚜렷하였다. 그리고 수직응력이 증가할수록 절리면의 이방성 효과는 감소하였다. 따라서 낮은 수직응력 하에서 전단강도 및 강성값을 보다 정확히 구하기 위해서 Barton의 식에 전단방향을 고려한 보정함수 F(a)를 반영하여 새로이 수정식을 제안한다.

• Structural Engineering and Mechanics
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• 제76권2호
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• pp.153-162
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• 2020

Aiming at the mechanical and structural characteristics of the contact zone composite rock, the shear tests and numerical studies were carried out. The effects of the differences in mechanical properties of different materials and the normal stress on shear properties of contact zone composite samples were analyzed from a macro-meso level. The results show that the composite samples have high shear strength, and the interface of different materials has strong adhesion. The differences in mechanical properties of materials weakens the shear strength and increase the shear brittleness of the sample, while normal stress will inhibit these effect. Under low/high normal stress, the sample show two failure modes, at the meso-damage level: elastic-shearing-frictional sliding and elastic-extrusion wear. This is mainly controlled by the contact and friction state of the material after damage. The secondary failure of undulating structure under normal-shear stress is the nature of extrusion wear, which is positively correlated to the normal stress and the degree of difference in mechanical properties of different materials. The increase of the mechanical difference of the sample will enhance the shear brittleness under lower normal stress and the shear interaction under higher normal stress.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.760-767
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• 2006

Underestimation of rock joint shear strength comes from an inadequate consideration of roughness mobilization behavior, which is changed by asperity size as well applied normal load. In this study, we performed rock joint shear tests, and studied the roughness mobilization characteristics related with the scale of normal stress and asperities. Test specimens with artificial triangular asperities were manufactured. The specimens consisted of 3 types, and each type represented unevenness, waviness and total roughness(superposition of unevenness and waviness). The experimental results show that the roughness mobilization characteristics are varied by the scale of normal stress and asperities. Furthermore, the investigation shows that the rate of geometrical component and mechanical component in the total roughness is also varied by the scale of normal stress and asperities. These results suggest that we should consider the roughness mobilization characteristics for the roughness quantification and the shear strength modelling.

• The Journal of Korean Physical Therapy
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• 제24권2호
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• pp.98-106
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• 2012

Purpose: The goal of this study was to analyze the degree of stress and methods of coping with stress in mothers of cerebral palsied children and to provide a basic resource for the development of policies to improve the mental health of mothers with cerebral palsied children. Methods: 85 mothers with cerebral palsied children and 77 mothers of normal children completed a self-administered questionnaire that evaluated the degree of stress and methods of coping with stress. Cronbach's ${\alpha}$ score was used to determine the internal consistency of the acquired data and the discriminated validity was estimated by Pearson's correlation coefficient. Independent t-tests were conducted to compare the degree of stress and method of coping with stress between mothers of cerebral palsied children and mothers of normal children and one-way ANOVA was performed to analyze the effect of generalized characteristics on stress in mothers of cerebral palsied children. Results: The degree of stress in terms of anxiety response and roles as mother for mothers with cerebral palsied children was higher than mothers with normal children. However, there was no significant difference between two group in regards to the methods of coping with stress during a stressful episode. The degree of stress for mothers with cerebral palsied children was greater when the child was younger. Conclusion: Mothers of cerebral palsied children had higher stress than that of mothers with normal children and felt more stress when their child was younger. Therefore, these results suggest that health-based policies should be developed to improve the mental health of mothers with cerebral palsied children.

• Journal of Nutrition and Health
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• 제23권7호
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• pp.504-512
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• 1990

In experiment 1, dietary self-selection of the 3 macronutrients, protein, fat, and carbohydrate were examined in male rats given 3 food cups of 80% carbohydrate, 80% protein, and 70% fat diets simultaneously. All the rats showed normal growth pattern and organ weight, which means they have ability to select just right kinds and amounts of nurients in order to support their growth and development. Mean values of caloric intake, body weight gain, serum lipid values and empty carcass compositions were not significantly differ between the upper and lower quartile groups of fat proportion of empty carcass compared to the lower quartile group(LF). Same feeding design was employed in experiment 2 where the effect of mild electric stress on food selection was studied. The rats in both control and electric stress group revealed a normal growth curve and organ weights. The rats in both control and electric stress group revealed a normal growth curve and organ weights. The stress group showed higher caloric intake and body weight gain than control group, but no significant effects of stress on serum and empty carcass components was found. Even though normal rats seemed to select macronutrients according to their physiolosical needs, there were individual differences in food selection whether they were exposed to stress or not. Therefore life long individual food selection pattern may have a great influence on nutritional status and chronic degenerative diseases of eldery, and on aging process.