• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.369-374
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• 1993

Measurements of strain near a crack tip with electrical resistance strain gages do not usually provide a reliable value of stress intensity factor (K sub I) because of local yielding and limited regions for strain-gage placement. This paper attempted to define a valid region and to indicate procedures for locating and orienting the strain-gage to determine stress intensity factor accurately from one stain-gage readings.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.734-740
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• 2001

In this paper the stress intensity factor under uniform pressure in the arbitrarily-shaped plane crack configuration transformed elliptic crack by Mobius mapping are determined. Using Dysons formula Boussinesq-Papkovich potentials for mode I deformation are constructed. In the example the stress intensity factors are approximately calculated by least square method.

• Journal of Ocean Engineering and Technology
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• v.17 no.2
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• pp.54-59
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• 2003

The characteristics of the parameters for the probability distribution of fatigue crack growth life, using the non-Gaussian random process simulation method is investigated. In this paper, the material resistance to fatigue crack growth is treated as a spatial random process, which varies randomly on the crack surface. Using the previous experimental data, the crack length equals the number of cycle curves that are simulated. The results are obtained for constant stress intensity factor range conditions with stress ratios of R=0.2, three specimen thickness of 6, 12 and 18mm, and the four stress intensity level. The probability distribution function of fatigue crack growth life seems to follow the 3-parameter Wiubull,, showing a slight dependence on specimen thickness and stress intensity level. The shape parameter, $\alpha$, does not show the dependency of thickness and stress intensity level, but the scale parameter, $\beta$, and location parameter, ${\gamma}$, are decreased by increasing the specimen thickness and stress intensity level. The slope for the stress intensity level is larger than the specimen thickness.

• Journal of the Korea Society of Computer and Information
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• v.22 no.7
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• pp.109-115
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• 2017

This study was performed to investigate the changes in turnover intention according to the level of occupational stress and to find the mediating factor that reducing the turnover intention among fire officer. To compare change of turnover intention according to the degree of occupational stress, statistical analyses were done by using the logistic regression model. In logistic regression analysis, the possibility of high turnover intention in a group with high occupational stress was hjgher by 4.11 times than a group with low occupational stress. The results of analyzing the degree of change in turnover intention after applying the mediating parameters(physical condition, emotional labor, burn out), turnover intention decreased by about 50.6%(from 4.11 times to 2.03 times) at the high level of occupational stress. As a result, it was found that the occupational stress experienced by the fire-officers had a positive effect on the turnover intention. In order to reduce the turnover intention due to the occupational stress of the fire-officers, it is necessary to manage factors such as work environmental factors(emotional labor, burn out) and individual factor(physical condition).

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.301-306
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• 2002

The characteristics of parameters for the probability distribution of fatigue crack growth lives by the non-Gaussian random process simulation method is investigated. In this paper, the material resistance to fatigue crack growth is treated as a spatial random process, which varies randomly on the crack surface. Using the previous experimental data, the crack length - the number of cycles curves are simulated. The results are obtained for constant stress intensity factor range conditions with stress ratio of R=0.2, three specimen thickness of 6, 12 and 18mm, and the four stress intensity level. The probability distribution function of fatigue crack growth lives seems to follow the 3-parameter Wiubull and shows a slight dependence on specimen thickness and stress intensity level. The shape parameter, ${\alpha}$, does not show the dependency of thickness and stress intensity level, but the scale parameter, ${\beta}$, and location parameter, ${\upsilon}$, are decreased by increasing the specimen thickness and stress intensity level. The slope for the stress intensity level is larger than the specimen thickness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.554-561
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• 2012

The purpose of this study was to identify the relationship between anxiety, anger and fatigue among stress factor in clinical practice of nursing students. The subjects were 197 nursing students who have practiced at the hospital in T city. Data was analyzed by using descriptive statistics, ANOVA, t-test and pearson's correlation coefficient. The mean score for stress was 3.82. The mean score for anxiety was 48.82. The mean score for anger was 1.17. The mean score for fatigue was 30.96. The factor of stress was a significant difference of anxiety according to conference, theory and practice, satisfaction of clinical practice. The factor of stress was a significant difference of anger according to report, theory and practice, orientation, nurse, environment. The factor of stress was a significant difference of fatigue according to conference, orientation, environment, patient relationship. In results, This study revealed that there was a significant correlation among stress, anxiety, anger and fatigue of nursing students in clinical practice.

• Journal of Power System Engineering
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• v.16 no.2
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• pp.43-48
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• 2012

Generally accelerated life test is well known as one method to reduce reliability qualification test period. This test is conducted under the higher stress condition than normal condition. So it can save the test time by calculating the acceleration factor from the relationship between the worst stress condition and normal condition. This paper investigates the worst stress condition for the accelerated life test to increase the acceleration factor. Especially, we focused on the method to obtain effective acceleration factors under the worst stress condition. Moreover, we considered how to decide the worst stress condition by looking for the operating limit of this system. The acceleration factor can be estimated from the ratio of the kinematic viscosity in the normal condition and the worst stress condition, the lowest temperature, by using Arrhenius relationship. Through some experiments for a refrigerator's compressor, we were able to confirm how to increase acceleration factors and how to reduce the reliability qualification test period with minimum samples.

• The Journal of the Korea Contents Association
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• v.9 no.9
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• pp.359-369
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• 2009

This study is designed to figure out internship stress factors which took place in their work place of Hotel. Then, the relationship between these internship stress factors and internship satisfaction were explored. Lastly, the internship satisfaction of student under high stress in each stress factor and that of students under low stress were compared each other. five internship stress factors(internship-related stress, human relation stress, regulation stress regarding human resources, organization stress, and Foreign language barrier stress) were delineated from factor analysis. The levels of each internship stress sere significantly different based on several demographic variables. As like as other studies, there were negative relationship between stress and internship satisfaction. finally, the students with low stress in each stress factor except language barrier stress were more satisfied with their internship than those under high stress.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.43-48
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• 2004

When structures are loaded by a combination of primary and secondary stresses, plasticity effects occur which cannot be evaluated by a simple linear addition of the effects resulting from the two independent stress systems. Thermal stress due to temperature gradient is classified as secondary stress. It is known that secondary stress is released as increase of plastic zone. In this paper, two and three dimensional elastic-plastic finite element analyses are performed for the cracked plates and pipes under combined thermal and mechanical loading. And V-factor is introduced to account for plasticity effect. The present results provide that V-factor is function of thermal factor and loading and is consistent regardless of geometry. We developed the prediction method of elastic-plastic fracture mechanics parameter under combined primary and secondary loading from the present results.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.4
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• pp.80-88
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• 1997

An experimental investigation of the fatigue through crack growth behavior under simple stepped variable loading condition has been performed using Al7075-T651. Experiments were carried out by using cantilever bending type specimens, with chevron notches on a small electro-magnetic test machine. Tensile overloads have a retarding effect on the fatigue crack growth rates, therefore tensile overloads were used for the beneficial effect on the fatigue life. While in most cases compressive overloads have only a vanishing effect on crack growth rates, some experiments with single edge crack tension specimens reveal a marked growth retardation. The stress ratios used in this investigations varies from R=0.32 to 0.81, from R=0.04 to 0.76, from R=-0.15 to 0.73, and from R=-0.33 to 0.68 and the peak load for each case was not varied. The crack growth and crack closure were measured by Kikukawa's compliance method with a strain gauge mounted on the backside of each specimens. The results obtained are as follows. When the stepped variable load was applied, the smaller the stress ration was, the larger the delayed retardation of the crack growth rate was. The fatigue crack growh rate data obtained for through cracks were plotted well against the effective stress intensity factor range from 4.0 to 20.0MP{a^{SQRT}m}. It was found that the effective stress intensity factor range ratio was related well to the opening stress intensity factor, the maximum stress intensity factor, and crack length.