• Tribology and Lubricants
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• v.28 no.6
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• pp.272-277
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• 2012

Finite element analysis was carried out using wafer-scale and particle-scale models to understand the mechanism of the fast removal rate(edge effect) at wafer edges in the chemical-mechanical polishing process. This is the first to report that a particle-scale model can explain the edge effect well in terms of stress distribution and magnitude. The results also revealed that the mechanism could not be fully understood by using the wafer-scale model, which has been used in many previous studies. The wafer-scale model neither gives the stress magnitude that is sufficient to remove material nor indicates the coincidence between the stress distribution and the removal rate along a wafer surface.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.265-270
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• 2007

According to previous research, welding-induced residual stresses in steel structures can significantly affect the fatigue behaviour. Usually, high tensile residual stresses up to the yield strength are conservatively assumed at the weld toes. This conservative assumption can result in misleading fatigue assessments. Thee welding-induced residual stresses need be known in advance for a reliable fatigue assessment, which becomes possible to an increasing extent by numerical welding simulation. In this study, a fatigue Analysis technique for steel structures with welding induced residual stress is presented. First, We calculate the history of temperature according with welding process. Secondly, residual stress with a welding thermal history was evaluated by non-linear thermal stress analysis and lastly, fatigue strength is estimated with modified Goodman equation which can consider the effect of mean stress level.

• Transactions of Materials Processing
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• v.12 no.4
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• pp.302-307
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• 2003

Hot rolled strip is cooled by air and water in Run-Out-Table. In this process, phase transformation and shape deformation occurs due to temperature drop. Because of un-ideal cooling condition of ROT, irregular shape deformation and phase transformation arise in the strip. which affect the strip property and lead to the residual stress of strip. And these exert effects on the following processes, coiling process, coil cooling process, and re-coiling process. Through these processes, the residual stress becomes higher and severe. For the prediction of residual stress distribution and shape deformation of final product, Finite element(FE) based model was used. It consists of non-steady state heat transfer analysis, elasto-plastic analysis. thermodynamic analysis and phase transformation kinetics. Successive FEM simulation were applied from ROT process to coil cooling process. In each process simulation, previous process simulation results were used for the next process simulation. The simulation results were matched well with the experimental results.

• Structural Engineering and Mechanics
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• v.58 no.4
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• pp.661-676
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• 2016

This paper presents an elastic/plastic model that neglects strain hardening during loading, but accounts for the Bauschinger effect. These mathematical features of the model represent reasonably well the actual behavior of several materials such as high strength steels. Previous attempts to describe the behavior of this kind of materials have been restricted to a class of boundary value problems in which the state of stress in the plastic region is completely controlled by the yield stress in tension or torsion. In particular, the yield stress is supposed to be constant during loading and the forward plastic strain reduces the yield stress to be used to describe reversed yielding. The new model generalizes this approach on plane stress problems assuming that the material obeys the von Mises yield criterion during loading. Then, the model is adopted to describe reversed yielding in thin hollow discs subject to external pressure.

• Journal of the Korea Safety Management & Science
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• v.24 no.1
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• pp.21-30
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• 2022

Since the competitive environment, it has become common for firms to reduce its workforce to diminish operating cost. Accordingly, job insecurity among employees has been increasing. Previous works on job insecurity have not paid adequate attention to the influence of job insecurity on safety behavior. The current paper investigates the impact of job insecurity on safety behavior and its intermediating mechanisms. In specific, this paper delves into the mediating effect of job stress, as well as the moderating effect of servant leadership in the association between job insecurity and job stress. The results demonstrated that that job insecurity has a positive (+) influence on job stress, which has a negative (-) influence on safety behavior. Moreover, job stress mediated the association between job insecurity and safety behavior. Furthermore, servant leadership moderated the job insecurity-safety behavior link.

• Journal of the Korea Safety Management & Science
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• v.24 no.1
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• pp.39-48
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• 2022

Considering that previous works on safety behavior relatively have not paid adequate attention to the influence of various leadership styles on safety behavior. The current paper investigates the impact of authentic leadership on safety behavior and its intermediating mechanisms. In specific, this paper delves into the mediating effect of job stress, as well as the moderating effect of perspective taking ability of employees in the association between authentic leadership and job stress. The results demonstrated that that authentic leadership has a negative (-) influence on job stress, which has a negative (-) influence on safety behavior. Moreover, job stress mediated the association between authentic leadership and safety behavior. Furthermore, perspective taking moderated the authentic leadership-safety behavior link.

• Journal of the Korean Home Economics Association
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• v.29 no.2
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• pp.217-240
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• 1991

The primary purpose of this study is to construct a path model in which shows how the background variables, retirement-related variables, and perceptions of stress in retirement influence life satisfaction among retirees. Data from a probability sample of retirees who are not employed as a full - time (n of retirees=261)are used. The social stress model, developed by House (1974) and George (1980), presented and tested in this research focuses on the perspective of the retirees. The major findings are: 1. The retirees perceive relatively high levels of stress in retirement. 2. Levels of living standard, health status, and locus of control are significant factors in differentiating the degrees of perceived stress in retirement and life satisfaction. 3. Concerning the retirement variables, the previous job satisfaction, plans and preparatins for leisure activities and financial arrangement contribute to differentiate the degrees of perceived stress in retirement and life satisfaction. 4. While health status, locus of control, and the perceptions of stress in retirement influence directly on life satisfaction, age, education, income, and activity level influence indirectly through the retirement - related variables and the perceptions of stress in retirement on life satisfaction. The significant impact of the perceptions of stress in retirement upon life satisfaction receives strong support.

• Journal of the Korean Society of School Health
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• v.21 no.2
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• pp.1-11
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• 2008

Purpose: Few studies have attempted to explain the childhood's sociality issue in Korea. This study was conducted to investigate the association between obesity stress and sociality factors. Methods : The study subjects were 4th, 5th, and 6th grade students from the elementary schools in Kwangju, Anyang, and Hwasung city. The cross sectional study was carried out through the self-reported questionnaire survey about obesity stress, sociality, and socio-demographic characteristics. The data was analyzed by multiple regression analysis using SPSS 12.0 version. Results : Overall, the findings of this study were consistent with previous studies. The measures of obesity stress showed significant negative relationships with measures of childhood sociality. Specifically, the association between mental stress from obesity and socialization was more higher than other variables. In addition, multiple regression analysis found that the effect of mental stress from obesity on childhood sociality was more higher than the effect of stress from physical discomfort and the effort to overcome the obesity stress. Conclusion : Findings provide evidence for the notion that the measures of obesity stress is significantly associated with childhood sociality.

• 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.

• Interaction and multiscale mechanics
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• v.4 no.2
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• pp.85-105
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• 2011

The influence of surface elasticity and surface residual stress on the elastic field of an isotropic nanoscale elastic layer of finite thickness bonded to a rigid material base is considered by employing the Gurtin-Murdoch continuum theory of elastic material surfaces. The fundamental solutions corresponding to buried vertical and horizontal line loads are obtained by using Fourier integral transform techniques. Selected numerical results are presented for the cases of a finite elastic layer and a semi-infinite elastic medium to portray the influence of surface elasticity and residual surface stress on the bulk stress field. It is found that the bulk stress field depends significantly on both surface elastic constants and residual surface stress. The consideration of out-of-plane terms of the surface stress yields significantly different solutions compared to previous studies. The solutions presented in this study can be used to examine a variety of practical problems involving nanoscale/soft material systems and to develop boundary integral equations methods for such systems.