• 대한기계학회논문집A
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• 제22권2호
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• pp.278-288
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• 1998

An efficient and useful method to improve the local stress field in a displacement-formulated finite element solution has been proposed using the theory of conjugate approximations for a stress field and the Loubignac's iterative method for a displacement field. Validity of the proposed method has been tested through three test examples, to improve the stress field and displacement field in the whole domain and the local regions. As a result of analysis on the test examples, it is found that the stress field in the local regions are approximated to those in the whole domain within a few iterations which have satisfied the original finite element equilibrium equation. In addition, it is found that the local stress field are by far better approximated to the exact stress field than the displacement-based stress field with the reduction of the finite-element mesh-size.

• 가정간호학회지
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• 제20권1호
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• pp.44-52
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• 2013

Purpose: To identify factors that affect the job stress of visiting nurses at health centers in Seoul, Korea, who perform home care services. Methods: Data were collected in the period from November 20 to December 10, 2008, from 206 visiting nurses working at 25 health centers in Seoul metropolitan city. Self-report questionnaires of the Organization-Based Self-Esteem (OBSE) and the Korean Occupational Stress Scale (KOSS) were used. Data were analyzed by the SPSS win 15.0. Results: Several findings were obtained from the study. First, the mean of job stress was 52.4 points, which was higher than that of Korean women. Second, it was shown that by the sub-domain of job stress, the mean value belonged to the top 50% in the four sub-domains of physical environment, job demand, interpersonal conflict, and organizational system. Additionally, it belonged to the top 25% in the sub-domain of job insecurity, wherein the job stress was the highest. Third, the self-esteem of the nurses had the most significant effect on their job stress. Conclusion: Stress related to job insecurity was the highest among the visiting nurses at health centers in Seoul who perform the custom home care service thus, institutional support is urgently needed to alleviate such stress and secure their employment.

• BMB Reports
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• 제48권3호
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• pp.184-189
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• 2015

Src homology 2-containing protein tyrosine phosphatase 2 (SHP-2) is known to protect neurons from neurodegeneration during ischemia/reperfusion injury. We recently reported that ROS-mediated oxidative stress promotes phosphorylation of endogenous SHP-2 in astrocytes and complex formation between caveolin-1 and SHP-2 in response to oxidative stress. To examine the region of SHP-2 participating in complex formation with caveolin-1, we generated three deletion mutant constructs and six point mutation constructs of SHP-2. Compared with wild-type SHP-2, binding of the N-SH2 domain deletion mutant of SHP-2 to p-caveolin-1 was reduced greatly, using flow cytometric competitive binding assays and surface plasmon resonance (SPR). Moreover, deletion of the N-SH2 domain of SHP-2 affected $H_2O_2$-mediated ERK phosphorylation and Src phosphorylation at Tyr 419 in primary astrocytes, suggesting that N-SH2 domain of SHP-2 is responsible for the binding of caveolin-1 and contributes to the regulation of Src phosphorylation and activation following ROS-induced oxidative stress in brain astrocytes.

• 대한기계학회논문집
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• 제11권2호
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• pp.234-242
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• 1987

본 논문에서는 변분법으로 유도한 최적조건을 수치계산에 적용키 위해 영역적 응법이 사용되었으며 불규칙한 형상의 방지에는 격자 적응법이 제시되었다. 설계 문 제로는 '국부 응력치의 일정 한도내에서 구조물 무게의 최소화' 또는 대등한 문제로 '제한된 구조물의 무게한도내에서 최대 국부응력치의 최소화'를 다루었다.

• Geomechanics and Engineering
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• 제21권5호
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• pp.461-469
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• 2020

The objective of this paper is to study the deformation in a homogeneous isotropic modified couple stress thermoelastic medium with and without energy dissipation and with two temperatures due to thermal source and mechanical force. Laplace and Fourier transform techniques are applied to obtain the solutions of the governing equations. The displacement components, stress components, conductive temperature and couple stress are obtained in the transformed domain. Isothermal boundary and insulated boundary conditions are used to investigate the problem.The effect of two temperature and GN theory of type-II and type-III has been depicted graphically on the various components. Numerical inversion technique has been used to obtain the solutions in the physical domain. Some special cases of interest are also deduced.

• Structural Engineering and Mechanics
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• 제33권6호
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• pp.697-708
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• 2009

Stresses are solved for two parallel cracks in an infinite orthotropic plate during passage of incoming shock stress waves normal to their surfaces. Fourier transformations were used to reduce the boundary conditions with respect to the cracks to two pairs of dual integral equations in the Laplace domain. To solve these equations, the differences in the crack surface displacements were expanded to a series of functions that are zero outside the cracks. The unknown coefficients in the series were solved using the Schmidt method so as to satisfy the conditions inside the cracks. The stress intensity factors were defined in the Laplace domain and were inverted numerically to physical space. Dynamic stress intensity factors were calculated numerically for selected crack configurations.

• Steel and Composite Structures
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• 제34권2호
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• pp.309-319
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• 2020

The objective is to study the deformation in a homogeneous isotropic modified couple stress thermoelastic medium with mass diffusion and with two temperatures due to a thermal source and mechanical force. Laplace and Fourier transform techniques are applied to obtain the solutions of the governing equations. The displacements, stress components, conductive temperature, mass concentration and couple stress are obtained in the transformed domain. Numerical inversion technique has been used to obtain the solutions in the physical domain. Isothermal boundary and insulated boundaryconditions are used to investigate the problem. Some special cases of interest are also deduced.

• Steel and Composite Structures
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• 제38권2호
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• pp.213-221
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• 2021

The objective of this paper is to study the deformation in a homogeneous isotropic thermoelastic solid using modified couple stress theory subjected to ramp-type thermal source with two temperature. The advantage of this theory is the involvement of only one material length scale parameter which can determine the size effects. Laplace and Fourier transform technique is applied to obtain the solutions of the governing equations. The components of displacement, conductive temperature, stress components and couple stress are obtained in the transformed domain. A numerical inversion technique has been used to obtain the solutions in the physical domain. The effect of two temperature is depicted graphically on the resulted quantities. Numerical results show that the proposed model can capture the size effects of microstructures.

• Coupled systems mechanics
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• 제12권3호
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• pp.261-276
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• 2023

This article is an application of new modified couple stress thermoelasticity without energy dissipation in association with two-temperature theory. The upper and lower surfaces of the plate are subjected to an axisymmetric heat supply. The solution is found by using Laplace and Hankel transform techniques. The analytical expressions of displacement components, conductive temperature, stress components and couple stress are computed in transformed domain. Numerical inversion technique has been applied to obtain the results in the physical domain. Numerically simulated results are depicted graphically. The effect of two temperature is shown on the various components.

• Structural Engineering and Mechanics
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• 제75권3호
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• pp.357-367
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• 2020

The objective of this article is investigation of dynamic response of thick multilayer functionally graded (FG) beam under generalized dynamic forces. The plane stress problem is exploited to describe the constitutive equation of thick FG beam to get realistic and accurate response. Applied dynamic forces are assumed to be sinusoidal harmonic, sinusoidal pulse or triangle in time domain and point load. Equations of motion of deep FG beam are derived based on the Hamilton principle from kinematic relations and constitutive equations of plane stress problem. The numerical finite element procedure is adopted to discretize the space domain of structure and transform partial differential equations of motion to ordinary differential equations in time domain. Numerical time integration method is used to solve the system of equations in time domain and find the time responses. Numerical parametric studies are performed to illustrate effects of force type, graduation parameter, geometrical and stacking sequence of layers on the time response of deep multilayer FG beams.