• Korean Journal of Occupational Health Nursing
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• v.18 no.2
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• pp.153-164
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• 2009

Purpose: This study investigates the relationship between job stress, depression, health-related behavior and type A behavior patterns among male workers at a steel factory. Methods: The study was done on 171 male workers, using the structured questionnaire. The data were collected in April, 2009 and analyzed by descriptive statistics, t-test, ANOVA, and pearson correlation coefficient. Results: The results showed that 65.5% of workers were under moderate stress, 25.7% high stress and 0.6% extremely high stress. The overall score of these workers' occupational stress was 41.9, lower than the Korean workers' average. Occupational stress was correlated with depression, type A behavior patterns, a very poor physical condition without sufficient sleep. Conclusion: Stress management program is strongly needed for these subjects working over 45 hours a week, with a very poor subjective physical condition, insufficient sleep, type A behavior patterns and signs of severe depression. Further longitudinal study is recommended to show the effect of such worker's stress management program to mitigate job-related stress.

• International Journal of Reliability and Applications
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• v.1 no.2
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• pp.155-165
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• 2000

In this paper, we propose some estimators of Kullback- Leibler Information functions using the data from three step stress accelerated life tests. This acceleration model is assumed to be a tampered random variable model. Some asymptotic properties of proposed estimators are proved. Simulations are performed for comparing the small sample properties of the proposed estimators under use condition of accelerated life test.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.70-75
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• 2002

It is generally applied constraint welding condition to structure manufacture in the industry field. But it is thinkable that the residual stress of the construction and specimens for experiment is different because not constraint welding but non-constraint welding are applied for experiment. To apply the constraint welding condition as the industry field and compare and evaluate the welding residual stress distribution, the TlG welding of the pure titanium was carried out under constraint and non-constraint welding conditions

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.357-361
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• 1995

An experiment on characteristics of nMOSFET's in the long stress condition with the maximum of the substrate current has been carried out in order to study on the degradation due to the hot-carrier effect. Based on the measured result of the threshold voltage, the damage is mostly due to the hole injection into the oxide. After long stress, it was shown that the drain current increased at low gate voltages and hence decreased at high gate voltages.

• Honam Mathematical Journal
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• v.38 no.3
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• pp.661-674
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• 2016

In [15] they introduced a new finite element method for accurate numerical solutions of Poisson equations with corner singularities, which is useful for the problem with known stress intensity factor. They consider the Poisson equations with homogeneous Dirichlet boundary condition, compute the finite element solution using standard FEM and use the extraction formula to compute the stress intensity factor, then they pose a PDE with a regular solution by imposing the nonhomogeneous boundary condition using the computed stress intensity factor, which converges with optimal speed. From the solution we could get accurate solution just by adding the singular part. This approach works for the case when we have the accurate stress intensity factor. In this paper we consider Poisson equations with mixed boundary conditions and show the method depends the accrucy of the stress intensity factor by considering two algorithms.

• Journal of Welding and Joining
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• v.15 no.1
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• pp.55-65
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• 1997

The stress intensity factor has been calculated for the cracked plate subjected to remote normal stress and reinforced with a plate by symmetric spot welding. The solution was based on displacement compatibility condition between the cracked sheet and the reinforcement plate. It is shown that the results from the derived equation for stress intensity factor were agreed with previous solutions. The reinforcement effect gets better as a joining spot is closer to the crack tip and the other joining spots become nearer to the crack surface.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.306-312
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• 1992

The prevention of roll breakage in hot rolling process is improtant to reduce maintenance cost and production loss. Rolling conditions such as the roll force and torque have been intensively studied to overcome the roll breakage. in the present work, a model for life prediction of work rolls under working condition was developed and discussed. The model consists of stress analysis, crack propagation, wear and fatigue calculation model. Roll life can be predicted by stress, crack depth and fatigue damage calculated from this model. The reliability of stress analysis is backed up by the FEM analysis. From the result of simulation using by pressent model, although the fatigue damage of back up roll reachs 80% of practical limit, that of workroll was less than 40%. In edge section of workroll stress amplification is found by wear and bender effect. We can judge that workroll failures are not due to fatigue damage, crack propagation by bending stress but stress amplification by wear and bender in present working condition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.307-310
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• 1998

Finite element analysis was investigated on the stress distribution at the 2-D model of piezoelectric ceramic actuators. The y direction maximum stress decreased with a(internal electrode gap) size until 0.4 mm and is not much difference with c(external electrode thickness) size. The stress distribution with internal layers is almost same, and the stress distribution of load condition is higher than that of no load condition. The y direction maximum stress increased exponentially with the number of layer and saturated at 260 layers. In the case of defective actuator, the stress distribution is smaller than that of normal actuator.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.1
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• pp.73-80
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• 2006

Sesame (Sesamum indicum L.) seeds contain abundant oil and antioxidative lignans related to the seed quality. To evaluate the potential effects of drought stress on the chemical composition of sesame seeds, eighteen cultivars were imposed water-deficit condition by withholding irrigation during 15 days at podding and maturing stage, compared with well-watered plants as control in seed yield and chemical composition. Drought treatments showed great decrease of seed yield with not affecting seed weight. The contents of sesamin and sesamolin decreased while lignan glycosides inversely increased in response to drought stress. Oil content was not significantly changed by drought treatment in spite of its slight decrease. In case of fatty acid composition, there were significant differences in increase of oleic acid while inverse decrease of linoleic acid under drought stress condition. These results demonstrate that the chemical composition of sesame seed may be modified with drought stress. In particular, the increase of sesaminol glucosides with strong antioxidative activity was observed.

• Journal of Biosystems Engineering
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• v.17 no.3
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• pp.260-271
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• 1992

Fruits are generally subjected to mechanical forces during harvesting, handling, and transportation that may cause damage in the form of bruises, punctures, and cracks. In order to prevent damage, and insure better quality fruits for consumers, it is very essential to study physical properties of these materials. The studies were conducted to examine the effect of storage period, storage condition, and other factors, such as loading rate and initial strain, on the stress relaxation behavior of the fruit flesh, and develop nonlinear viscoelastic models to represent its stress relaxation behavior. The following results were obtained from the study : 1. Since the viscoelastic behavior of the fruits flesh was nonlinear, the behavior was satisfactorily modelled as follows ; $${\delta}({\varepsilon},\;t)={\varepsilon}^A[B\;{\exp}(-Ct)+D\;{\exp}(-Ft)+G(-Ht)]$$ But, for the every strain applied, the stress relaxation behavior of the fruit flesh, such as apple and pear, could be well described by the Generalized Maxwell model, respectively. 2. The effect of loading rate on the stress relaxation behavior was remarkable. The higher loading rate resulted in the higher initial stress, and the faster stress relaxation. 3. The higher initial strain resulted in the higher initial stress, and stress relaxed at the large initial strain was also much higher than at the small initial strain. 4. Stress relaxation rate and quantity stored in the fruits at the low temperature storage were much higher than those at the normal temperature storage in the same storage period. Also, in all fruits tested, the longer storage period was the more relaxation rate and quantity were shown. These trends in the normal temperature condition was the more significant than in the low temperature condition.