• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.496-499
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• 2006

In this study, a practical method of shrinkage stress analysis on concrete slab in multi-story building is proposed, which considers both internal restraint and external restraint variation resulting from construction sequence. The shrinkage stress due to external restraint is obtained by multiplying relaxation coefficient to elastic shrinkage stress. The additional shrinkage stress due to internal restraint is obtained by residual strain of the elastic analysis. A verification example was analyzed and compared by the proposed method and commercial analysis program that is capable of time-dependent analysis of concrete. The results of 10-story example building show that the internal restraint of reinforcement increases the shrinkage stress considerably at the slabs under loose external restraint.

• Journal of Korean Academy of Nursing
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• v.22 no.4
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• pp.526-551
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• 1992

The purpose of this study was to identify the commonalities of various nursing interventions and effective intervention methods in each intervention through analysis and synthesis of many accumulated research papers. The study analyzed the effects of various nursing interventions on anxiety and /or stress. For this purpose, 64 experimental studies with randomized or nonequivalent control group pre-test-posttest design were selected from journals of medical and nursing schools, the Korean Nurse, the Korean Nurses' Academic Society Journal, the Cetnral Journal of Medicine, the New Medical Journal, the Nurse Monthly, and from theses and dissertations conducted from 1970 to 1991. The selected studies nor classified according to three characteristics : 1) the research samuel, 2) types and methods of nursing interventions, and 3) statistical tests. The following analysis was done : 1) Confirmation of the accuracy of data drawn from each study by paired review, 2) Estimation of the homogenity of pre-test scores of the dependent variable between control and experimental groups warranted the effect size of post-scores, 3) If the homogenity of pre-test scores did not warrant, the change scores from pre-test to post-test were used to estimate the effect size, 4) Use of the effect size of each study among homogenious studies was tested for each intervention method, such as relaxation, information, and touch and /or support. Finally, for the studies not showing homogenity, an ANOVA test was used to identify patterns for each intervention. Some findings are summarized as follow : The effect sizes for relaxation and information were greater than those for touch and /or supportive technique. Studies using random assignment had greater effect sizes than nonrandomized sample studies using the same intervention. For healthy people, group education was more effective than individual teaching. However, for patients, relaxation and touch and /or supportive techniques given on individual basis were more effective than when given in a group situation. Measuring anxiety and stress by biological indicators was less effective than by self-report. Budzynski's relaxation method was the most effective. The more frequently the techniques applied, the larger the effect size. On the bases of these findings, the following recommendations were made : 1. A combination of information, relaxtion, and touch-supportive techniques should be used for greater effect in reducing the level of anxiety and /or stress. 2. Information is the first choice of intervention to reduce the level of anxiety and /or stress of healthy People : other interventions may be added depending on the conditions of the subjects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1065-1073
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• 2009

In this paper, the estimation method of C(t)-integral for combined mechanical and thermal loads is proposed for elastic-plastic-creep material via 3-dimensional FE analyses. Plasticity induced by initial loading makes relaxation rate different from those produced elastically. Moreover, the interactions between mechanical and thermal loads make the relaxation rate different from those produced under mechanical load alone. To quantify C(t)-integral for combined mechanical and thermal loads, the simplified formula are developed by modifying redistribution time in existing work done by Ainsworth et al..

• Journal of Advanced Marine Engineering and Technology
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• v.7 no.2
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• pp.29-35
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• 1983

In general, for measuring residual stresses in plane stress state, two principal stresses {\sigma}_1 , {\sigma}_2$ and their directions .theta., should be determined. Naturally, for deciding three unknowns ${\sigma}_1, {\sigma}_2, ${\theta}$-three informations are necessary and therefore three strain gages are required for determining residual stresses at one point. In this paper, we tried to measure the residual stresses of one point with only two strain gages by drilling twice the hole of different diameters at the point and by detecting relaxation strains for each hole-drilling. We present also the formulas for determining the residual stresses from relaxation strains detected by strain gages in each hole-drilling. We carried out experiment, determining principal stresses and their directions of specimens applied specified uniform stress, and compared experimental results with the values calculated by formulas presented in this paper. The values calculated by formulas presented in this paper are always a little greater than the experimental results.

• Journal of Korean Medical Ki-Gong Academy
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• v.7 no.1
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• pp.98-126
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• 2003

Objectives : Riding stance has been basic traning of chinese martial arts and Gi-gong. The aim of this study is to observe history, methods, effect of riding stance. Methods : Compare riding stances of each family of martial arts and Gi-gong. Result : 1. Since Wang, the father of Daesung-Gwon had created Chamjang-gong, riding stance becomes a independent foam of Gi-gong 2. The essential method of riding stance is Relaxing the upper body, straightening the spine and putting stress on inner side of the legs. 3. Putting stress on inner legs help relaxing upper body. 4. Riding stance is very similar to horse-back riding. 5. Relaxation must be done for effective riding stance training. Conclusions : Riding stance is necessary for stressful modern people.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.191-194
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• 2007

In hot embossing lithography which has shown to be a good method to fabricate polymeric patterns for IT and bio components, it is very important to determine the proper process conditions of pressure, temperature, and time. It is also a key factor for predicting the optical properties of final product to calculate residual stress distribution after the embossing process. Therefore, to design the optimum process with right conditions, the ability to predict viscoelastic behavior of polymer during and after the hot embossing process is required. The objective of the present investigation is to establish simulation technique based on constitutive modeling of polymer with experiments. To analyze deformation behavior of viscoelastic polymer, the large strain material properties were obtained from quasi-static compression tests at different strain rates and temperatures and also stress relaxation tests were executed. With this viscoelastic material model, finite element simulation of hot embossing was executed and stress distribution is obtained. Proper process pressure is very important to predict the defect and incomplete filling.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.3
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• pp.290-296
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• 2005

The contour method is based on the elastic superposition principle, and relies on deformations that occur when a residually stressed part is cut along a plane. During the cut, the part is constrained at a location along the cut so that deformations are restrained as much as possible. The displacement is applied to an elastic FE model of the half. When plasticity is involved in the relaxation process, the superposition principle is no longer valid, and stress error in the resulting measurement of residual stress would be caused. Residual stress states in a laser peened Ti-6Al-4V strip were taken for the FE simulation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.4
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• pp.75-82
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• 2021

The objective of this study is to examine the loss of prestressing stress in the developed prestressing reinforcing units using steel bar and pipe (SP). The main parameters were the reinforcing bar type, the magnitude of prestressed force, and prestressing method. The test results showed that the loss of prestressing stress for SP was highest in the initial prestressing step, which was higher for the compression introduction typed specimens than tension introduction typed specimens. The loss of prestressing stress of SP made with P800 was 1.6% for the compression introduction typed specimen with 0.8f_y, which was lowest than the other specimens. Meanwhile, the relaxation of SP with the respect to the time ranged between 0.4 and 1.9%, irrespective of SP material type, the magnitude of prestressed force, and prestressing method. These values were less than 2.5%, which is the maximum value for the relaxation of prestressed reinforcing steel bars in design codes. Consequently, considering the loss of stress developed in the initial prestressing step, the developed SP material type, prestressing introduction method, and magnitude are recommended to be P800, compression introduction type, and 0.8f_y.

• Steel and Composite Structures
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• v.49 no.2
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• pp.125-141
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• 2023

Firstly, a new kind of prismatic tensegrity structures with redundant cables is defined, the topology, geometry and forming conditions of which are introduced further. The development of its mechanical properties including self-stress states and structural stiffness with the increment of the twist angle is also investigated carefully. Combined with the topology of this kind of structures, a reasonable erection scheme is proposed, in which some temporary lifting points need to be set and two groups of vertical cables are tensioned in batches. Then, a simplified dynamic relaxation method is employed to track the erection process inversely, which aims to predict each intermediate equilibrium state during the construction, and give the key structural parameters that can effectively guide the construction. The removal of the active cables, the relaxation or tension of the passive cables are simulated by controlling their axial stiffness, so that the structural composition as well as the serial numbers of the elements always keep invariant regardless of the withdrawal of the slack cables. The whole analysis process is clear in concept, simple to implement and easy to popularize. Finally, several examples are given to verify the practicability and effectiveness of the proposed method further.

• Journal of Welding and Joining
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• v.22 no.2
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• pp.51-58
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• 2004

Residual stresses, which can be produced during the welding process, play an important role in an industrial field. Welding residual stresses are exerting negative effect on the fatigue behavior and integrity of structure. In this study, as a result of the thermal elasto-plastic finite element analysis for the welds of a nuclear component, the residual stress distributions are estimated for as-welded condition. Also, finite element techniques are developed to simulate the relaxation of the residual stresses according to the various mechanical stress relieving(MSR) loads such as hydrostatic pressure loading, tensile pipe-end loading, and mechanical stress improvement process(MSIP) loading. Finally, the results of residual stress redistributions for various loading conditions are compared and reviewed qualitatively and quantitatively to find an optimum loading condition.