• Journal of Information Technology Applications and Management
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• 제27권6호
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• pp.15-29
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• 2020

Previous studies on the relationship between stress and performance have shown inconsistent results. Thus, this study focused on the effect of challenging stress among the two types of stress types and investigated the nonlinear relationship between the challenging stress and the performance. In particular, performance was divided into job performance, which is related to in-role behavior, and organizational citizenship behavior, which is characterized as extra-role behavior. Empirical results using 222 samples of Chinese workers have showed that challenging stress had a nonlinear relationship with job performance and organizational citizenship behavior. However, it was found that the shape of nonlinear relationship of the challenging stress on job performance and organizational citizenship behavior was slightly different. Finally, the theoretical and practical implications of this paper and future research directions are discussed.

• 대한정형외과스포츠의학회지
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• 제9권1호
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• pp.65-68
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• 2010

15세 씨름선수에서 발생한 주두의 횡상 골절 1례에서 골이식 및 내고정 치료를 시행 후, 술 후 6주에 골유합 소견을 확인하고 능동적 근력강화 운동을 통하여 술 후 6개월에 기존 강도의 운동으로 복귀하였다. 18세 야구선수에서 발생한 주두의 사선상골절 1례에 대해서는 안정 및 근력강화운동을 통한 보존적 치료를 시행하였으며, 3개월 후 통증이 완화되어 투구 운동을 재개하였고, 6개월 후 기존 강도의 운동으로 복귀하였다.

• Journal of Preventive Medicine and Public Health
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• 제54권2호
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• pp.86-95
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• 2021

Objectives: This study investigated associations between perceptions of coronavirus disease 2019 (COVID-19) and the prevalence of posttraumatic stress disorder (PTSD) in workers at hospitals designated to treat COVID-19, as well as the difference in the magnitude of these associations by occupational type and previous Middle East respiratory syndrome coronavirus (MERS-CoV) experience. Methods: The participants were workers at hospitals designated to treat COVID-19 who completed a questionnaire about their perceptions related to COVID-19, work experience during the previous MERS-CoV outbreak, and symptoms of PTSD ascertained by the PTSD Checklist for the Diagnostic and Statistical Manual of Mental Disorders. Participants' characteristics were compared using the chi-square test. Multivariable logistic regression was performed to evaluate the associations between perceptions and the prevalence of PTSD, stratified by occupational type and previous MERS-CoV experience. Results: Non-medical personnel showed stronger associations with PTSD than medical personnel according to general fear (odds ratio [OR], 6.67; 95% confidence interval [CI], 1.92 to 23.20), shortages of supplies (OR, 1.29; 95% CI, 1.07 to 1.56), and issue-specific fear (OR, 1.29; 95% CI, 1.05 to 1.59). Those with prior MERS-CoV quarantine experience were more prone to PTSD than those without such experience in terms of general fear (OR, 1.70; 95% CI, 1.22 to 2.37), shortages of supplies (OR, 1.24; 95% CI, 1.10 to 1.40), and issue-specific fear (OR, 1.21; 95% CI, 1.06 to 1.38). Conclusions: During the COVID-19 pandemic, non-medical personnel tended to have higher odds of being categorized as having PTSD. Workers with prior MERS-CoV experience were more susceptible than those without such experience. These findings suggest the need for timely interventions to manage human resources for a sustainable quarantine system.

• International Journal of Reliability and Applications
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• 제15권2호
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• pp.125-150
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• 2014

Accelerated life tests (ALTs) are extensively used to determine the reliability of a product in a short period of time. Test units are subject to elevated stresses which yield quick failures. ALT can be carried out using constant-stress, step-stress, progressive-stress, cyclic-stress or random-stress loading and their various combinations. An ALT with linearly increasing stress is ramp-stress test. Much of the previous work on planning ALTs has focused on constant-stress, step-stress, ramp-stress schemes and their various combinations where the stress is generally increased. This paper presents an optimal design of ramp soak-stress ALT model which is based on the principle of Thermal cycling. Thermal cycling involves applying high and low temperatures repeatedly over time. The optimal plan consists in finding out relevant experimental variables, namely, stress rates and stress rate change points, by minimizing variance of reliability function with pre-specified mission time under normal operating conditions. The Burr type XII life distribution and time-censored data have been used for the purpose. Burr type XII life distribution has been found appropriate for accelerated life testing experiments. The method developed has been explained using a numerical example and sensitivity analysis carried out.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.234-237
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• 2003

Previous researches about headed reinforcement have not been concerned about bond failure which is quite important is some cases. In this paper, failure mechanism including bond failure was presented in order to define the contribution of bond stress at the time failure occurs. Examined with design codes and test results, it is proved to be rational to consider the contribution of bond stress in determining the ultimate pull-out capacity of headed reinforcement. Direct adaptation of design code for anchor bolt without modification for the contribution of bond stress will lead to underestimate the capacity of headed reinforcement.

• 대한기계학회논문집
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• 제19권2호
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• pp.463-474
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• 1995

Modified Vainshtok weight function method is developed. The thermal shock stress intensity factors for elliptical surface cracks existed in the thin and thick walled cylinders are determined. The present results are compared with previous solutions and shown to be good agreement with them.

• 한국지반공학회논문집
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• 제16권6호
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• pp.35-41
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• 2000

Residual stress is defined as a minimum stress with a large displacement of specimens and the residual stress after peak shear stress appears with displacement volume but there is no provision to select the residual stress. In the previous study, residual stress was recorded when the change of shear load is small in the condition of the strain more than 15%. But, in this study, hyperbolic function((No Abstract.see full/text), b=experimental constant) of soil test is adapted to joint of rock and the propriety is investigated. In a landslide and landsliding of artificial slope, wedge failure of tunnel with a large displacement, tests are simulated from peak stress to residual stress for safety analysis. But now. direct shear stress and triaxial compressive tests are usually performed to find out characteristics of shear stress about joint. Although these tests get a small displacement, that data of peak stress and residual stress are used for safety analysis. In this study, we tried to determine failure criteria for joints of rock using ring shear test machine. The residual stress following shear behavior was determined by the result of ring shear test and direct shear test. In conclusion, after comparing the results of the two test, we found that cohesion(c) and internal friction angle(ø) of ring shear test are 30% and 22% respectively of those of the direct shear test.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.60-64
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• 2008

According to previous research, welding-induced stress in steel structures can significantly affect the fatigue behaviour; it produces initial damage of weldiug part of structure locally and residual stresses reduce the fatigue strength after welding precess. In this study, through continuum damage mechanics, we can estimate the weldiug damage using the stress and strain history during welding process and the effect of welding residual stress for assessment of fatigue life. The variation of welding-induced stresses and strains need be traced precisely in advance for a reliable weldiug damage assessment. In this study, a damage and fatigue analysis techniques for steel structures with welding-induced residual stress are presented. First, We calculate the history of temperature according with welding process. And residual stress with a welding thermal history was evaluated by non-linear thermal stress analysis. Secondly, welding damage and fatigue life are estimated with kinetic damage law.

• Structural Engineering and Mechanics
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• 제61권3호
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• pp.317-323
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• 2017

This work presents a new strategy to model stress dependent relaxation process in large deformation. The strategy is relied on the fact that in some particular soft materials undergoing large deformation, e.g., elastomers, rubbers and soft tissues, the relaxation time depends strongly on stress levels. To simplify the viscoelastic model, we consider that the relaxation time is the function of previous elastic deviatoric stress state experienced by materials during loading. Using the General Maxwell Model (GMM), we simulate numerically conditions with the constant and the stress dependent relaxation time for uniaxial tension and compression loading. Hence, it can be shown that the proposed model herein not only can represent different relaxation time for different stress level but also maintain the capability of the GMM to model hysteresis phenomena.

• 한국공간구조학회논문집
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• 제15권1호
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• pp.47-55
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• 2015

This paper shows the simplified equation to predict the ultimate moment capacity and corresponding rod stress in reinforced concrete beam with external post-tensioning rods. Because the stress of external post-tensioning rod depends on the beam deflection, the previous analytical model for post-tensioned beams requires a tedious iteration process. Also, the stress equations in ACI code or other researchers' models are suitable only for internal tendons in concrete beams. In this study, given the lack of analytical approaches to predict the nominal stress of the external unbonded rod, a simple and robust equation has been proposed for externally post-tensioned concrete beams. It is concluded that the proposed equation predicted the stress of external steel rods in post-tensioned concrete beams reasonably well.