• Journal of Oral Medicine and Pain
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• 제20권2호
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• pp.385-397
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• 1995

The purpose of this study is to document the stress symptoms (Anxiety and depression) among dental students and the difference of stress level between classes and by gender. All students in dental college, Seoul National University, in the 1995 academic year, were tested with the Spielberger's State-Trait Anxiety Inventory and Beck Depression Inventory just before the first semestral examination when the stress levels of students are expected to be the highest. 303 students answered the test. The obtained results were as follows : 1. State Anxiety inventory scores of the second-year and first-year students were significantly higher than those of the fourth -year and third-year(p(0.01), and all classes showed mean state anxiety scores more than mild. 2. Trait Anxiety inventory scores of the second-year and first-year students were significantly higher than those of the third-year and forth-year(p(0.01), and all classes showed mean Trait Anxiety scores more than mild. 3. Beck Depression inventory scores of the second -year students were significantly higher than those of the third-year and fourth-year(p(0.01), and twenty two students(7.3%) among the fourth classes showed depression symptoms. 4. In the comparison of the mean scores of the State-Trait Anxiety Inventory and Beck Depression Inventory between male and female students, State Anxiety Inventory scores of the second-year female students were significantly higher than those of the second year male students(p(0.05), and there was no significant difference elsewhere.

• 인간식물환경학회지
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• 제22권3호
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• pp.309-319
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• 2019

This study was conducted to investigate the effects of watching a virtual reality (VR) forest video on stress reduction in adults. Experiments were performed in an artificial climate chamber where temperature, humidity and illumination were controlled. To cause stress in subjects, the subjects were asked to multiply two digit numbers by one digit numbers for two minutes. The subjects then watched a VR forest video for five minutes. During the experiment, the heart rate variability (HRV) and heart rate (HR) of subjects were continuously measured for evaluating their physiological state. After measuring the baseline and watching a VR forest video, their psychological state was evaluated using the profile of mood state (POMS), semantic differential (SD) method, and positive affect and negative affect schedule (PANAS). The results of physiological evaluation after watching a VR forest video showed a decrease in the stress index and HR, an increase in the activity of the parasympathetic nervous system, and the standard deviation of normal to normal RR intervals (SDNN). The results of psychological assessment confirmed that watching a VR forest video induced "comfort", "natural", and "soothed" feelings in subjects. In addition, watching a VR forest video decreased "tension-anxiety (T-A)", "depression-dejection (D)", "anger-hostility (A-H)", "fatigue (F)", "total mood disturbance (TMD)", and increased "vigor (V)" compared to the base line, and decreased "negative affect" and increased "positive affect." These results indicate that watching a VR forest video decreases adults' stress index, stabilizes physiological state, and has a positive impact on psychological state. The findings of this study can serve as a basis for providing forest welfare services to people in the blind spots of forest welfare, and can lay a foundation for the adoption of VR, one of the technologies of the fourth industrial revolution in forestry.

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.115-120
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• 1990

The spectroscopic properties of Cr3+-doped sapphire and Ti3+-doped sapphire fibers are reported. Tensile stress produces blue shifts of the R lines and changes in their radiative lifetimes and integrated intensities which can be correlated to stress-induced changes of the crystal-field parameters in a Cr3+-doped sapphire fiber. A net red shift of the zero phonon fluorescence line of 2Eg state and a decrease of the splittings of 2T2g state with uniaxial stress are observed in a Ti3+-doped sapphire. In excitation spectra the two peaks from the 2Eg state are shifted to the blue with different rates. The changes are attributed to the stress-induced changes of crystal field and Jahn-Teller effect.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.561-564
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• 1999

The uniform state of prestress in a fully prestressed concrete members shows reductions of more than half of the initial prestress in the construction and coupling joint vicinity. Especially, at a zone x/d=0.2 above the construction joint where at the edge of the member, a quite localized reduced stress state of 1/3 of uniform stress is encountered. Five full-scale test specimens were segmentally constructed and post-tensioned and analytic models is used to verify and validate measured test results. The encountered highly nonuniform stress/strain state in the coupling joint vicinity requires special design consideration for the successful application of tendon couplers.

• 한국자동차공학회논문집
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• 제22권5호
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• pp.44-49
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• 2014

As expansion and contraction of bike disk brake are happened continuously by temperature at repeated urgent braking. In this study, 3 kinds of model are designed according to configurations of holes and thermal durabilities on bike disk brake are investigated by comparing 3 models through temperature and thermal analyses. Maximum thermal stress happened at the disk contacted with pad and the connection part fixing disk rotor. Instead of initial state, the temperature is uniformly distributed at transient state. As the area of hole at disk rotor face becomes wider, thermal stress becomes lower at the initial state. On the other hand, in case the number of holes increases, thermal stress becomes lower at the elapsed time of 100 seconds. The thermal durability of bike disk brake can be improved by applying this study result with configurations of holes.

• 한국농공학회지
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• 제41권2호
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• pp.70-79
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• 1999

The lower ground of structure, in which the strip loads, such as earth dams and embankments , are signiificantly working on , is required to be interpreted as a state of plane strain where the strain of intermediated principal stress direction is put '0' . The plane strain state is frquently observed in actural soil engineering case. For those case, drained stress-strain and strength behavior of Iksan weathered granite soil prepared in cubical specimens with cross-anisotropic fabric was studied by conventional triaxial compression, plane strain and cubial triaxial tests with independent control of the three principal stress. All specimens were loaded under conditions of principl stress directions fixed and aligned with the directions of the material axes. As a result of research , when a ground condition is analyzed under plane strain state, the shear strength obtained from the conventional triaxial compression test can be understimated.

• 한국기계가공학회지
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• 제14권1호
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• pp.78-84
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• 2015

The stress state acting on mechanical parts and structures is generally mixed stress. This complex stress state, which is subject to changes in the environment, will produce many. Cars running on roads with different road conditions will subject the automotive parts to combined stress state. In the x direction and the y direction, a different amplitude and frequency of the fatigue load can be present. However, the load amplitude for Mode I and Mode II in a 2-axis fatigue test is limited to a constant ratio; the load frequency is always the same for any mode. In this paper, it is verified how the variation of the load frequency for mode II affects the behavior of fatigue crack propagation under mixed mode.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.425-430
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• 2003

The material properties of rubber was determined by the experiments of uniaxial tension, uniaxial compression, planer tension, equi-biaxial tension and volumetric compression. In compression test, it is difficult to obtain the pure state of compression stress and strain due to friction force between the specimen and compression platen. In this study, the stress and strain data from the equi-biaxial tension test were converted to compression stress and strain and compared to a perfect state of simple compression data when friction was zero. The compression test device with the tapered platen was proposed to overcome the effect of friction. It was turned out that the relationship of the stress and strain using the tapered platen was in close agreement with the pure compressive state.

• 한국자동차공학회논문집
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• 제11권5호
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• pp.95-104
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• 2003

The material properties of rubber was determined by the experiments of uniaxial tension, uniaxial compression, planer tension, equi-biaxial tension and volumetric compression. In compression test, it is difficult to obtain the pure state of compression stress and strain due to friction force between the specimen and compression platen. In this study, the stress and strain data from the equi-biaxial tension test were converted to compression stress and strain and compared to a pure state of simple compression data when friction was zero. The compression test device with the tapered platen was proposed to overcome the effect of friction. It was fumed out that the relationship of the stress and strain using the tapered platen was in close agreement with the pure compressive state.

• 성인간호학회지
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• 제16권1호
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• pp.90-101
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• 2004

Purpose: The purpose was to examine the effectiveness of a psychosocial stress management program on stress and coping in student nurses. Method: A nonequivalent control group pre-posttest design was used. A convenience sample of 24 students from the Department of Nursing, Wonju College of Medicine, Yonsei University were assigned to experimental (n=12) and control groups(n=12). Stress was measured using the Visual Analog Scale (10 points) and blood cortisol. Coping was measured using a scale modified by So (1995) based on the Ways of Coping Checklist developed by Folkman and Lazarus (1985). Depression was measured using the CES-D by Radloff (1977) and state anxiety, using the State Anxiety Inventory by Spielberger (1976). The psychosocial stress management program included education, relaxation (Korean Dan Jeon-typed Breathing and music), and social support. Result: Results showed for the two groups, 1) a significant difference in stress scores (U= 19.50, p=0.002), 2) no difference in cortisol levels (8am, 4pm), 3) a significant difference in problem-focused coping (U=25.50, =0.007), 4) no difference in emotion-focused coping, and 5) no difference in state anxiety and depression. Conclusion: By utilizing the program, students were able to learn how to control their stress and improve their coping. Therefore with a partial modification, psychosocial stress management can be useful for continual management of stress in student nurses.