• Safety and Health at Work
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• v.5 no.4
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• pp.186-190
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• 2014

Background: Physical exercise during leisure time is known to increase physical capacity; however, the long-term effects on work ability and work strain are inconclusive. The aim of this study was to investigate the effects of a 6-month physical exercise program on work ability and work strain after 6 months and 30 months, among women with menopausal symptoms at baseline. Methods: A questionnaire including questions on work ability and work strain was mailed in the beginning, at 6 months and after 30 months after the intervention to occupationally active women participating in a randomized controlled study on physical exercise and quality of life. The intervention included aerobic exercise training 4 times per week, 50 minutes per session. Work ability was measured with the Work Ability Index (WAI) and with questions about physical and mental work strain. Results: Women aged 47-62 years (N=89) who were occupationally active at baseline were included in the analyses. The increase in WAI from baseline to the end of the exercise intervention (6 months) was statistically significantly greater among the intervention group than among the control group (regression coefficient 2.08; 95% confidence interval 0.71-3.46). The difference between the groups persisted for 30 months. No significant short- or long-term effects on physical and mental work strain were found. Conclusion: A 6-month physical exercise intervention among symptomatic menopausal women had positive short-term as well as long-term effects on work ability.

• Journal of Families and Better Life
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• v.27 no.4
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• pp.117-126
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• 2009

The purpose of this study was to analyze the difference of working mothers' work-child rearing strain and their demand on special care services according to each mother's work conditions and childcare situation. 477 working mothers who have only one child each were gathered by the use of the purposive quota sampling method and analyzed with t-test, F-test, correlation, and multiple regression. The main results showed that working mothers had high work-child rearing strain and demand on special care services when their working conditions were inflexible and they were not satisfied with the care services for their child. The major variable which explained working mothers' demand on special care services was e their work-child rearing strain.

• Structural Engineering and Mechanics
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• v.58 no.4
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• pp.719-729
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• 2016

The main objective of the present paper is to study the effect of the yield criterion on the magnitude of the strain rate and plastic work rate intensity factors in axisymmetric flow of isotropic incompressible rigid perfectly plastic material by means of a problem permitting a closed-form solution. The boundary value problem consisting of the axisymmetric deformation of a plastic tube is solved. The outer surface of the tube contracts. The radius of the inner surface does not change. The material of the tube obeys quite a general yield criterion and its associated flow rule. The maximum friction law is assumed at the inner surface of the tube. Therefore, the velocity field is singular near this surface. In particular, the strain rate and plastic work rate intensity factors are derived from the solution. It is shown that the strain rate intensity factor does not depend on the yield criterion but the plastic work rate intensity factor does.

• Transactions of Materials Processing
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• v.15 no.8 s.89
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• pp.544-549
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• 2006

In this work, we have employed the strain gradient plasticity theory to investigate the effect of material size on the deformation behavior in metal forming process. Flow stress is expressed in terms of strain, strain gradient (spatial derivative of strain) and intrinsic material length. The least square method coupled with strain gradient plasticity was used to calculate the components of strain gradient at each element of material. For demonstrating the size effect, the proposed approach has been applied to plane compression process and micro rolling process. Results show when the characteristic length of the material comes to the intrinsic material length, the effect of strain gradient is noteworthy. For the microcompression, the additional work hardening at higher strain gradient regions results in uniform distribution of strain. In the case of micro-rolling, the strain gradient is remarkable at the exit section where the actual reduction of the rolling finishes and subsequently strong work hardening take places at the section. This results in a considerable increase in rolling force. Rolling force with the strain gradient plasticity considered in analysis increases by 20% compared to that with conventional plasticity theory.

• The Journal of Korean Physical Therapy
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• v.31 no.4
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• pp.254-259
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• 2019

Purpose: This study examined the interactions between the job strain and social support in the workplace on the development of workrelated neck pain in office workers. Methods: The participants included 62 office workers without neck pain over the last twelve months. A battery of measures evaluating the potential workplace risk factors in office settings were conducted at the baseline, and at the 12 month incidence of work-related neck pain was reported via monthly questionnaires. Survival analysis evaluated the interaction effect between job strain and social support on the development of work-related neck pain. Results: The incidence of work-related neck pain was 1.91 (95% CI: 1.06 - 3.45) per 100 person months. The interaction effect between job strain and social support found that job strain may increase the risk of developing new work-related neck pain when lower social support existed in the workplace. On the other hand, the adverse effects of job strain on the development of neck pain were not significant when workers had higher social support from their colleagues and supervisors. Conclusion: An investigation of the moderating effects of risk factors on neck pain might reveal the unexplained relationship between the risk factors for the development of neck pain in office workers. Therefore, the interest in prevention plans and treatments should involve a comprehensive understanding of the risk factors at workplace.

• Nuclear Engineering and Technology
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• v.8 no.3
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• pp.151-157
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• 1976

The strain ageing behavior of cold-worked Zircaloy-4 in vacuum was studied as a function of deformation temperature and oxygen content from 1143 ppm to 3500 ppm 0. Strain ageing occured in the temperature range between 200 and 45$0^{\circ}C$ for the 0 to 10% cold-worked Zircaloy-4, decreasing with increasing amount of cold work. This suppression of strain ageing by cold work is considered to be due to the trapping of oxygen atoms by cold work-produced defects. It has been found that the maximum strain ageing stress in cold-worked Zircaloy-4 is proportional to the square root of oxygen content.

• Safety and Health at Work
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• v.9 no.4
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• pp.454-461
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• 2018

Background: Working conditions and psychosocial work factors have acquired an important role explaining the well-being and performance of professional drivers, including those working in the field of public transport. This study aimed to examine the association between job strain and the operational performance of public transport drivers and to compare the expositions with psychosocial risk at work of three different types of transport workers: taxi drivers, city bus drivers, and interurban bus drivers. Method: A sample of 780 professional drivers was drawn from three transport companies in Bogota (Colombia). The participants answered the Job Content Questionnaire and a set of sociodemographic and driving performance questions, including age, professional driving experience, work schedules, and accidents and penalties suffered in the last 2 years. Results: Analyses showed significant associations between measures of socio-labor variables and key performance indicators such road traffic accidents and penalties. Furthermore, multiple linear regression analysis contributed to explain significantly suffered accidents from key variables of the Job Demand-Control model, essentially from job strain. In addition, throughout post-hoc analyses, significant differences were found in terms of perceived social support, job strain, and job insecurity. Conclusion: Work stress is an issue that compromises the safety of professional drivers. This research provides evidence supporting a significant effect of job strain on the professional driver's performance. Moreover, the statistically significant differences between taxi drivers, city bus drivers, and interurban bus drivers in their expositions to work-related stress suggest the need for tailored occupational safety interventions on each occupational group.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.5
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• pp.750-757
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• 2003

In order to determine creep stress intensity limit of high-temperature components, the usefulness of the creep work and time equation, defined as W$\_$c/t$\^$p/ = B(where W$\_$c/ = $\sigma$$\varepsilon$ is the total creep work done during creep, and p and B are constants), was investigated using the experimental data. For this Purpose, the creep tests for generating 1.0% strain for commercial type i16 stainless steel were conducted with different stresses; 160 MPa, 150 MPa, 145 MPa, 140 MPa and 135 MPa at 593$^{\circ}C$. The plots of log W$\_$c/ - log t showed a good linear relation up to 10$\^$5/ hr, and the results of the creep work-time relation for p, B and stress intensity values showed good agreement to those of isochronous stress-strain curves (ISSC) presented in ASME BPV NH. The relation can be simply obtained with only several short-term 1% strain data without ISSC which can be obtained by long-term creep data. Particularly, this relation is useful in estimating stress intensity limit for new and emerging class of high-temperature creeping materials.

• Transactions of Materials Processing
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• v.1 no.1
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• pp.42-51
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• 1992

The ring compression test has been widely employed as an experimental means to determine the friction factor. The calibration curves are obtained by the rigid-plastic finite element analysis for various work-hardening exponent and strain-rate hardening exponent. The effects of work-hardening exponent and strain-rate hardening exponent are thoroughly studied and discussed from the finite element computation. The change of friction factor during height reduction in ring compression is also discussed. Then, the method to estimate the change of friction factor during ring compression is proposed.

• Geomechanics and Engineering
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• v.35 no.5
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• pp.465-473
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• 2023

The higher order shear deformable model and an exact analytical method is used for analytical bending analysis of a cylindrical shell subjected to mechanical loads, in this work. The shell is modelled using sinusoidal bivariate shear strain theory, and the static governing equations are derived using changes in virtual work. The eigenvalue-eigenvector method is used to exactly solve the governing equations for a constrained cylindrical shell The proposed kinematic relation decomposes the radial displacement into bending, shearing and stretching functions. The main advantage of the method presented in this work is the study of the effect of clamping constraints on the local stresses at the ends. Stress, strain, and deformation analysis of shells through thickness and length.