• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 춘계학술발표대회 개요집
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• pp.171-174
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• 2002

• Structural Engineering and Mechanics
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• 제44권3호
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• pp.289-303
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• 2012

Existing plane stress solutions for thin plates and disks have shown several qualitative features which are difficult to handle with the use of commercial numerical codes (non-existence of solutions, singular solutions, rapid growth of the plastic zone with a loading parameter). In order to understand the effect of temperature and pressure-dependency of the yield criterion on some of such features as well as on the distribution of residual stresses and strains, a semi-analytic solution for a thin hollow disk fixed to a rigid container and subject to thermal loading and subsequent unloading is derived. The material model is elastic-perfectly/plastic. The Drucker-Prager pressure-dependent yield criterion and the equation of incompressibity for plastic strains are adopted. The distribution of residual stresses and strains is illustrated for a wide range of the parameter which controls pressure-dependency of the yield criterion.

• 한국산학기술학회논문지
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• 제18권6호
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• pp.209-218
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• 2017

본 연구는 대학생의 사회적 지지(가족의 사회적 지지, 친구의 사회적 지지), 심리적 행동특성(자기존중감, 대인의존행동특성, 통제신념) 및 스트레스가 우울수준에 미치는 영향을 알아보기 위해 실시하였다. 조사대상은 D광역시의 남녀 대학생 546명으로 하였으며, 연구방법은 2015년 10월에 자기기입식 설문조사에 의하였다. 연구결과, 조사대상자의 우울수준은 가족의 사회적 지지, 친구의 사회적 지지, 자기존중감 및 통제신념이 높은 군보다 낮은 군에서 유의하게 높은 반면, 대인의존행동 특성과 스트레스가 낮은 군보다 높은 군에서 유의하게 높았다. 또한, 조사대상자의 우울수준은 가족의 사회적 지지, 친구의 사회적 지지, 자기존중감 및 통제신념과는 유의한 음의 상관관계를 보인 반면, 대인의존행동특성 및 스트레스와는 유의한 양의 상관관계를 보였다. 공분산 구조분석 결과, 스트레스원의 인지는 사회적 지지의 인지나 심리적 행동특성보다 우울수준에 더 큰 영향을 미쳤으며, 스트레스원의 인지가 높을수록, 사회적 지지의 인지나 심리적 행동특성이 낮을수록 우울수준을 증가시키는 효과가 있는 것으로 나타났다. 위와 같은 결과는 대학생들의 우울수준은 사회적 지지와 심리적 행동특성이 낮고, 스트레스가 높을 경우 증가한다는 것을 시사하고 있으며, 특히 다른 요인들보다 스트레스에 의해 더 큰 영향을 받고 있음을 알 수 있다. 따라서 대학생들의 우울수준을 감소시키기 위해서는 학생들이 경험하는 주요 스트레스원이 무엇인지 파악하고 스트레스원을 감소시키기 위한 노력이 필요하다고 생각된다.

• 한국지반공학회논문집
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• 제21권7호
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• pp.73-80
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• 2005

도로기초에서 입상재료의 응력의존 특성을 반영하면 응력의존 탄성계수와 응력 의존 포와송 비 모두를 동시에 고려할 수 있다. 이 방식은 기존 연속체 역학에 기초한 해석 방식과는 달리 층모형 내에서 인장력의 발생 대신 압축력의 구현이 가능하여 재료의 강성과 연성에 대한 거동을 동시에 반영하여 입상재료층의 변형 예측에 많은 영향을 주고 있다 따라서 본 논문에서는 도로기초를 대상으로 제안된 응력의존 및 변형 모형을 대상으로 유한요소법에 의한 도로기초 층변형 예측 알고리즘을 제안하였고 층변형 예측시 응력의존의 고려에 따른 영향을 분석하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1199-1203
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• 2008

It has been recognized that unsaturated soil behavior plays an importantrole in geomechanics. In the last decade several constitutive models have been proposed and used in the analysis. Many of them, however, are constructed in the frame work of rate independent model such as elasto-plastic one. Although rate dependency is an important characteristics of soil for both saturated and unsaturated soils, very few models have been developed taking account of rate dependency. In the present paper, we have developed an elasto-viscoplastic model considering an effect of suction based on the overstress-type viscoplasticity with soil structure degradation. In the model, we have adopted an averaged pore pressure composed of pore water pressure and air pressure to determine the effective stress.

• Asian Pacific Journal of Cancer Prevention
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• 제15권18호
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• pp.7629-7634
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• 2014

Background: Cigarette smokers have their own motivation and justification to smoke. For example, smoking reduces their stress or enhances their pleasure. This study aimed to identify the (a) prevalence of cigarette smokers among undergraduates in Malaysia, (b) gender differences in nicotine dependence among current smokers, (c) differences in psychological problems (depression, anxiety and stress) based on the status of smoking cigarettes (current, former and non-smokers) and (d) extent to which precipitating factors (tension reduction, addiction, automatism, handling, social interaction, pleasure, and stimulation) predict the smoking behavior among current smokers. Materials and Methods: In this study 780 undergraduate students participated from a private university in Kuala Lumpur and Selangor state in Malaysia. The Depression, Stress and Anxiety Scale, Modified Reason for Smoking Scale and Fagerstrom Nicotine Dependence Test were used to measure psychological problems, predictors of smoking behavior and nicotine dependency among current smokers. Results: The results showed that 14.7%(n=106) of the students were smokers. Current smokers exhibited more psychological problems (depression, anxiety and stress) compared to former and non-smokers. Addiction, tension reduction, pleasure and automatism were predictors of smoking behavior among the current smoking students. Step wise regression analysis showed that smoking behavior was highly predicted by nicotine dependency or addiction. Smoking students were motivated to smoke cigarettes as they believed that it reduced their tension and enhance pleasure. Conclusions: Hence, there is a need for health promotion and anti-tobacco prevention as cigarette smokers experience more psychological problems. Nicotine dependency or addition was one of the major causes for smoking behavior among the student population in Malaysia.

• 터널과지하공간
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• 제6권2호
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• pp.101-121
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• 1996

The thermomechanical characteristics of rocks such as temperature dependency of strength and deformation were experimentally investigated using Iksan granite, Cheonan tonalite and Chung-ju dolomite for proper design and stability analysis of underground structures subjected to temperature changes. For the temperature below critical threshold temperature $T_c$, the variation of uniaxial compressive strength, Young's modulus, Brazilian tensile strength and cohesion with temperature were slightly different for each rock type, but these mechanical properties decreased at the temperatures above $T_c$ by the effect of thermal cracking. Tensile strength was most affected by $T_c$, and uniaxial compressive strength was least affected by $T_c$. To the temperature of 20$0^{\circ}C$ with the confining prressure to 150 kg/$\textrm{cm}^2$, failure limit on principal stress plane and failure envelope on $\sigma$-$\tau$ plane of Iksan granite were continuously lowered with increasing temperature but those of Cheonan tonalite and Chung-ju dolomite showed different characteristics depending on minor principal stress on principal stress plane and normal stress on $\sigma$-$\tau$ plane. The reason for this appeared to be the effect of rock characteristics and confining pressure. Young's modulus was also temperature and pressure dependent, but the variation of Young's modulus was about 10%, which was small compared to the variation of compressive strength. In general, Young's modulus increased with increasing confining pressure and increased or decreased with increasing temperature to 20$0^{\circ}C$ depending on the rock type.

• Journal of Korean Biological Nursing Science
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• 제9권2호
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• pp.135-142
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• 2007

Purpose: This study was conducted to investigate degree of stress level in CCU patients, and to give a baseline data in developing nursing intervention program to reduce the stress. Method: Subjects of this study were the 100 hospitalized patients of C University Hospital in Seoul City from February to December 2003. The collected data was analyzed by using the SAS program: t-test, Scheff$\acute{e}$ test, and ANOVA analysis were employed to find differences in stress level. Result: The highest stress factor was 'Concern', and next were 'Dependency & limitation', 'Uncertainty', 'Treatment procedure', 'Sleep disturbance', 'Environment' in order. The perceived stress level of CCU patients was 1.65 scores; the highest scored item was 'have to void urine and feces on the bed', next were 'have to use the toilet bowel lying on the bed' in order. The stress level according to characteristics of the subjects was significantly different with the marital status, the presence of religion, the hospitalized days, the economic status, and the admission experience. Conclusion: The stress level of patients in the coronary care unit was high in concern of a disease, family and economic state, in limitation and dependency, and in uncertainty about prognosis of a disease. Further researches are necessary to develop and apply the intervention method of reducing stress level of CCU patients. In addition studies on family members of CCU patients are also recommended.

• Journal of the Korean Wood Science and Technology
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• 제26권2호
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• pp.16-23
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• 1998

This paper examines the effects of specimen length and grade on the strength and stiffness properties of structural timber of radiata pine. The tensile strength and modulus of elasticity of 1,902 machine-graded boards with 3.15- and 1.62-m clear span lengths, were determined using a horizontal tension test machine. The mean failure and characteristic stress values for tensile strength show an extremely high dependency on test specimen length. The mean and characteristic values of both modulus of elasticity and tensile strength show significant dependency on machine stress grades.

• 한국농공학회지
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• 제40권1호
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• pp.106-117
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• 1998

The nature of stress-path dependency, the principle that governs deformations in granular soil, and the use of Lade's double work-hardening model for predicting soil response for a variety of stress-paths have been investigated, and are examined The test results and the analyses presented show that under some conditions granular soils exhibit stress-path dependent behavior. For stress-paths involving unloading or reloading, the stress-path with the higher average stress level produces the larger strains, whereas all stress-paths having the same intial states of stress, and involving only primary loading conditions, produce strains of similar magnitudes. Experimental evidence indicates that the stress- path dependent response obtained from the double work-hardening model is also observed for real soils. It is concluded that the influence of stress history on the friction angle is negligible and the strains increment direction is uniquely determined from the state of stress but is not perpendicular to the yield surface. The strains calculated from Lade's double work-hardening model are in reasonable agreement with those measured.