• Geomechanics and Engineering
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• v.16 no.1
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• pp.59-69
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• 2018

This study focused on the mechanical and hydraulic characteristics of underwater tunnels based on Mohr-Coulomb (M-C), Hoek-Brown (H-B) and generalized H-B failure criteria. An improved approach for calculating stress, displacement and plastic radius of the circular tunnel considering hydraulic-mechanical coupling was developed. The innovation of this study was that the radius-incremental-approach was reconstructed (i.e., the whole plastic zone is divided into a finite number of concentric annuli by radius), stress and displacement of each annulus were determined in terms of numerical method and Terzaghi's effective stress principle. The validation of the proposed approach was conducted by comparing with the results in Brown and Bray (1982) and Park and Kim (2006). In addition, the Rp-pin curve (plastic radius-internal supporting pressure curve) was obtained using the numerical iterative method, and the plastic radius of the deep-buried tunnel could be obtained by interpolation method in terms of the known value of internal supporting pressure pin. Combining with the theories in Carranza and Fairhurst (2000), the improved technique for assessing the reliability of the tunnel support was proposed.

• Geomechanics and Engineering
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• v.5 no.5
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• pp.379-399
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• 2013

In practice, analysis of laterally loaded piles is carried out using beams on non-linear Winkler springs model (often known as p-y method) due to its simplicity, low computational cost and the ability to model layered soils. In this approach, soil-pile interaction along the depth is characterized by a set of discrete non-linear springs represented by p-y curves where p is the pressure on the soil that causes a relative deformation of y. p-y curves are usually constructed based on semi-empirical correlations. In order to construct API/DNV proposed p-y curve for clay, one needs two values from the monotonic stress-strain test results i.e., undrained strength ($s_u$) and the strain at 50% yield stress (${\varepsilon}_{50}$). This approach may ignore various features for a particular soil which may lead to un-conservative or over-conservative design as not all the data points in the stress-strain relation are used. However, with the increasing ability to simulate soil-structure interaction problems using highly developed computers, the trend has shifted towards a more theoretically sound basis. In this paper, principles of Mobilized Strength Design (MSD) concept is used to construct a continuous p-y curves from experimentally obtained stress-strain relationship of the soil. In the method, the stress-strain graph is scaled by two coefficient $N_C$ (for stress) and $M_C$ (for strain) to obtain the p-y curves. $M_C$ and $N_C$ are derived based on Semi-Analytical Finite Element approach exploiting the axial symmetry where a pile is modelled as a series of embedded discs. An example is considered to show the application of the methodology.

• Journal of Families and Better Life
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• v.25 no.5
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• pp.107-126
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• 2007

This study explored the buffering effect of family resilience between family stress and adjustment of single parent family based on family resilience approach. Results of the study were as followed: First, single parents who had a lower level of family stress and a higher lever of family resilience reported a higher level of family adjustment. Second, family stress especially economic stress and relational stress influenced negatively on adjustment of single parent family. Family belief system, organizational pattern and communication processes of the three sub-factors of family resilience influenced positively on family adjustment. However the sub-factors of family resilience had more powerful effects than family stress. Third, family belief system, organizational pattern and communication processes of the three sub-factors of family resilience had a moderating effect between family adjustment and psychological stress and between family adjustment and relational stress. Especially the three sub-factors of family resilience had a buffering effect between family adjustment and relational stress. The results of this study had important implication for theory, research, and practice. The study showed that adjustment of single parent family could be significantly explained by family resilience rather than family stress. Accordingly strength perspective-based intervention focused on family resilience would be more effective than deficit perspective-based intervention based on family stress.

• Tribology and Lubricants
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• v.20 no.5
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• pp.252-258
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• 2004

In this study, using high cycle fatigue (HCF) criteria, the simulation of rolling contact fatigue is conducted under elliptical contact. The HCF criteria fall into three categories: the critical plane approach, the stress invariant approach and the approach based on the mesoscopic scale. The accurate calculation of contact stresses and subsurface stresses is essential to the prediction of crack initiation life. Contact stresses are obtained by contact analysis of a semi-infinite solid based on the use of influence functions and the subsurface stress field is obtained using rectangular patch solutions. The simulation results show that the critical load is decreasing rapidly and the site of crack initiation also moves rapidly to the surface from the subsurface when the friction coefficient exceeds a specific value for all of three fatigue criteria.

• Nuclear Engineering and Technology
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• v.47 no.3
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• pp.340-350
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• 2015

This paper proposes strain-based acceptance criteria for assessing plastic instability of the safety class 1 nuclear components made of ferritic steel during level D service loads. The strain-based criteria were proposed with two approaches: (1) a section average approach and (2) a critical location approach. Both approaches were based on the damage initiation point corresponding to the maximum load-carrying capability point instead of the fracture point via tensile tests and finite element analysis (FEA) for the notched specimen under uni-axial tensile loading. The two proposed criteria were reviewed from the viewpoint of design practice and philosophy to select a more appropriate criterion. As a result of the review, it was found that the section average approach is more appropriate than the critical location approach from the viewpoint of design practice and philosophy. Finally, the criterion based on the section average approach was applied to a simplified reactor pressure vessel (RPV) outlet nozzle subject to SSE loads. The application shows that the strain-based acceptance criteria can consider cumulative damages caused by the sequential loads unlike the stress-based acceptance criteria and can reduce the overconservatism of the stress-based acceptance criteria, which often occurs for level D service loads.

• Steel and Composite Structures
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• v.23 no.1
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• pp.41-51
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• 2017

A $C^0$ FE model developed based on an efficient higher order zigzag theory is used for hygrothermal analysis of laminated composite plates. The $C^0$ FE model satisfies the inter-laminar shear stress continuity at the interfaces and zero transverse shear stress conditions at plate top and bottom. In this model the first derivatives of transverse displacement have been treated as independent variables to circumvent the problem of $C^1$ continuity associated with the above plate theory. In the present theory the above mentioned $C^0$ continuity of the present element is compensated in the stiffness matrix formulation by using penalty parameter approach. In order to avoid stress oscillations observed in the displacement based finite element, the stress field derived from temperature/moisture fields (initial strains) must be consistent with total strain field. Special steps are introduced by field consistent approach (e.g., sampling at gauss points) to compensate this problem. A nine noded $C^0$ continuous isoparametric element is used in the proposed FE model. Comparison of present numerical results with other existing solutions shows that the proposed FE model is efficient, accurate and free of locking.

• Journal of the Korean Home Economics Association
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• v.44 no.4 s.218
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• pp.191-205
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• 2006

The purpose of the study was to develop family-based intervention program to be implemented and disseminated via "Healthy Family-Support Center." This preventive-empowerment program was designed to intervene with parenting mildly handicapped children enrolled at integrated kindergarten. The theoretical backgrounds employed were ecological theory, preventive family-based intervention approach, and theraplay theory. The pretest-posttest control-group design with random assignment was applied. The research model yielded a significant intervention effect(t=-1.294, p<0.05) on mothers' parenting stress. With proven effectiveness of family-based intervention program, the study further discussed why an ecological, family-based intervention model was a relevant alternative to investigate issues in family welfare, and why an individualized family service plan was a relevant tool to deliver services-in-context for the families who needed supports from exo-and macrosystems.

• Journal of Preventive Medicine and Public Health
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• v.43 no.5
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• pp.445-450
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• 2010

Objectives: Emotional support and a stress management program should be simultaneously provided to clients as effective preventive services for healthy behavioral change. This study was conducted to review various relaxation and meditation intervention methods and their applicability for a preventive service program. Methods and results: The author of this paper tried to find various relaxation and meditation programs through a literature review and program searching and to introduce them. The 'Relaxation Response' and 'Mindfulness Based Stress Reduction (MBSR)' are the most the widely used meditative programs in mainstream medical systems. Abdominal breathing, Progressive Musclular Relaxation (PMR), Relaxative Imagery, Autogenic Training (AT) and Biofeedback are other well-known techniques for relaxation and stress management. I have developed and implemented some programs using these methods. Relaxation and meditation classes for cancer patients and a meditation based stress coping workshop are examples of this program. Conclusions: Relaxation and meditation seem to be good and effective methods for primary, secondary and tertiary preventive service programs. Program development and standardization and further study are needed for more and wider use of the mindbody approach in the preventive service area of medicine.

• Journal of Theoretical and Applied Mechanics
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• v.2 no.1
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• pp.31-50
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• 1996

In this paper, a finite element analysis based on the local approach concept to fracture in the continuum damage mechanics is performed to analyze ductile fracture in two dimensional quasi-static state. First an isotropic damage model based on the generalized concept of effective stress is proposed for structural materials in the context of large deformation. In this model, the stiffness degradation is taken as a measure of damage and so, the fracture phenomenon can be explained as the critical deterioration of stiffness at a material point. The modified Riks' continuation technique is used to solve incremental iterative equations. Crack propagation is achieved by removing critically damaged elements. The mesh size sensitivity analysis and the simulation of the well known shearing mode failure in plane strain state are carried out to verify the present formulation. As numerical examples, an edge cracked plate and the specimen with a circular hole under plane stress are taken. Load-displacement curves and successively fractured shapes are shown. From the results, it can be concluded that the proposed model based on the local approach concept in the continuum damage mechanics may be stated as a reasonable tool to explain ductile fracture initiation and crack propagation.

• The Journal of Economics, Marketing and Management
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• v.9 no.5
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• pp.1-13
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• 2021

Purpose: Purpose - This study investigates and aims to discuss regarding the employee's work stress and its relationship with employee's workability based on literature content analysis. Finally, this study will provide how employees can manage it and coexist while enjoying the benefits of a stress-free working environment. Research design, data, and methodology - The author collected many textual contexts from mostly peer-reviewed academic journals, which means that academic comprehensive integrity can be obtained by qualitative approach for this study with discussing and following a constructive review analysis. The content analysis aims to determine a textural dataset in the longtime frame from the newest textural information. Result - There is little doubt that this study was significant and relevant to the relationship between employee work stress and workability, indicating how organizations that manage their employees in a stress-free working environment. the present researcher separate the solutions into five categories according to the person or body responsible for the answers. Conclusion - The numerous solutions on how to deal with various stresses, the theoretical aspect of the solutions involving the theories developed by multiple past articles on how to solve work stress. In general, workability and work stress is a very large field of study. Another consideration is the numerous professionalisms in the world, and each has different ways stress is induced in the organization.