• Structural Engineering and Mechanics
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• v.58 no.5
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• pp.783-797
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• 2016

Exact solutions for stresses, strains, and displacements of a perforated rectangular plate by an arbitrarily located circular hole subjected to both linearly varying in-plane normal stresses on the two opposite edges and in-plane shear stresses are investigated using the Airy stress function. The hoop stress occurring at the edge of the non-central circular hole are computed and plotted. Stress concentration factors (the maximum non-dimensional hoop stresses) depending on the location and size of the non-central circular hole and the loading condition are tabularized.

• Structural Engineering and Mechanics
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• v.59 no.3
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• pp.527-537
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• 2016

We describe a stress analysis of a single leaf flexure under torsion in which the warping effect is considered. The theoretical equations for the warping normal stress (${\sigma}_{xx}$) and shear stresses (${\tau}_{xz}$ and ${\tau}_{xy}$) are derived by applying the warping function of a rectangular cross-sectional beam and the twist angle equation that includes the warping torsion. The results are compared with those of the non-warping case and are verified using finite element analysis (FEA). A sensitivity analysis over the length, width, and thickness is performed and verified via FEA. The results show that the errors between the theory of warping stress results and the FEA results are lower than 4%. This indicates that the proposed theoretical stress analysis with warping is accurate in the torsion analysis of a single leaf flexure.

• Journal of the Korean GEO-environmental Society
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• v.8 no.4
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• pp.27-39
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• 2007

This paper investigates numerically characteristics of the fluid flow in spatially correlated variable-aperture fractures under effective normal stress conditions. Spatially correlated aperture distributions are generated by using the geostaistical method (i.e. Turning Bands algorithm). In order to represent a nonlinear relationship between the effective normal stress and the fracture aperture, a simple mechanical formula is combined with a local flow model. Obtained numerical results indicate that the fluid flow is significantly affected by the geometry of aperture distribution varying according to the applied effective normal stress as well as the spatial correlation length of aperture distribution. Moreover, by using results simulated in this study, the modified Louis formula representing the relationship between the effective normal stress and the effective permeability of fracture is proposed.

• International Journal of Oral Biology
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• v.33 no.1
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• pp.7-12
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• 2008

PG has been well studied about effects of stress resistance. Although ZJ has been known that it had stress resistance effect since ancient times, its pharmacological properties and clinical applications have not been studied and reported until recently. Therefore, the purpose of this study is to determine whether effects of stress hormones, mechanism of stress protein could be induced by PG and ZJ of herb extract ingestion during stress exposure. In addition, this study identified expression of apoptosis factors related to stress. 1) Bcl-2 expression of the stressed rats decreased in comparison with the unstressed rats in heart and stomach. Bcl-2 expression of rats administered to PG was higher than the stressed rats in heart and that of rats administered to ZJ was higher than the stressed rats in stomach. 2) Stressed rats were decreased in p53 protein expression than normal rats. Thus, the results suggest stress-induced apoptosis is p53-independent apoptosis. And these results demonstrated that PG or ZJ administration helped to return from stress state to normal. 3) Clusterin expressed markedly in only salivary gland, but that of expression was no difference among four groups in tissues. Clusterin expression has no relation of stress-induced apoptosis.

• The Korean Journal of Nuclear Medicine
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• v.31 no.1
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• pp.57-66
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• 1997

We performed 1st day Tc-99m-sestamibi gated SPECT with dipyridamole/rest T1-201 SPECT and 2nd day 24 hour delay T1-201 SPECT/rest Tc-99m-sestamibi gated SPECT in 27 patients with coronary artery disease(24) or having chest pain(3). Stress and rest Tc-99m-sestamibi gated SPECT was acquired at 60min post-injection. A 4-point scoring system(0 to 3 for normal to absent tracer uptake) for 17 segments was used. Wall motion was scored on another 4 point scale(0 to 3 for normal to dyskinesia) in the 1st day post-stress gated and the 2nd day rest gated SPECT. Post-stress gated SPECT showed wall motion abnormality in 94 segments(20%). Fifty-five segments among these 94 showed the same wall motion between post-stress and rest gated SPECT: i.e. 1-1 23 segments, 2-2: 29 segments, 3-3: 3 segments. Remaining 39 segments(41.5%) showed different wall motion between post- stress and rest Tc-99m-sestamibi gated SPECT. Twenty one segments with wall motion abnormality had normal perfusion(rest : 15 segments, 24 hour delay: 6 segments) at either rest or 24 hour delay. Fifteen among these 21 segments showed persistent post-stress and the 2nd day rest wall motion abnormality(persistent stunning). However, in 6 segments with pro-longed (1 hour after stress) stunning, abnormal wall motion did improve in the 2nd day rest Tc-99m-sestamibi gated SPECT(transient prolonged stunning). These 6 segments had normal perfusion at rest(n=4) or at 24 hour delay(n=2). Post stress wall motions showed significantly higher scores in persistent stunning than in prolonged transient stunning(P value<0.05). It was concluded that we could find stunned myocardium with gated Tc-99m-sestamibi SPECT at either post-stress or rest and that some myocardial walls of post-stress 1 hour gated SPECT did not show truly rest wall motion. So, we should be cautious if we use post-stress Tc-99m-sestamibi wall motion to assess rest wall motion.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.06a
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• pp.145-154
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• 2003

When a nail pulled out in dense, granular soil, the soil in the vicinity of the nail tends to dilate, but its dilatancy results in a normal stress concentration at the soil/nail interface, thereby increasing the pull-out resistance of the inclusion. It is thought to be occurring within the resistance zone where the soil mass is at stationary state and the reinforcement are held in position by the soil, due to the friction or bond. In this paper, A series of direct shear and interface tests were conducted by using so called‘Constant Normal Stiffness Test Apparatus’which was modified and improved from the conventional direct shear box test rig. Unlikely the normal shear box test, this enables to simulate the different constraint effects of surrounding soil during shear under the conditions of constant stress and volume, constant normal stiffness. The aim of the research programme is to get better understanding of pull-out bond mechanism, thus to explore the possibility of evaluating the pull-out bond capacity of soil/reinforcement at the preliminary design stage from the laboratory test.

• Water Engineering Research
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• v.6 no.2
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• pp.49-61
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• 2005

This paper presents the numerical study to examine characteristics of fluid flow and solute transport in a rough fracture subject to effective normal stresses. The aperture distribution is generated by using the self-affine fractal model. In order to represent a nonlinear relationship between the supported normal stress and the fracture aperture, we combine a simple mechanical model with the local flow model. The solute transport is simulated using the random walk particle following algorithm. Results of numerical simulations show that the flow is significantly affected by the geometry of aperture distribution varying with the effective normal stress level while it is slightly affected by the fractal dimension that determines the degree of the fracture surface roughness. However, solute transport is influenced by the effective normal stress as well as the fracture surface roughness.

• The Korean Journal of Zoology
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• v.7 no.1
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• pp.23-28
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• 1964

120 mice of both sexes weighing from 18 to 22 g. were used. These mice were divided nito 12 groups : control (non-restraint and restraint) , acclinmation (non-restraint and restraint , acclimation for 5 and 10 days) , adrenalectomized (non-restraint and restraint0 and acclimation-adrenalectomized (non-restraint and restraint, acclimation for 5 and 10 days) groups. The rectal temperature of each group were measured at 10, 30 and 50 min under environment of $0^{\circ}C$.Measurements were done with a microphrometer of B.T.-32 thermocorpules. The results obtained may be summarized as follows : 1) The rectal temperature in normal mice without restraint was higher than that of normal mice with restraint under environment of $0^{\circ}C$. 2) The rectal temperature in normal mice was higher than that of adrenalectomized mice at 20$^{\circ}$ C. But the rectal temperature in adrenalectomized mice without restraint was higher than that of adrenalectomized mice with restraint under cold-stress. This difference was in the order of 1.65$^{\circ}$ under environment of 20$^{\circ}$ and 10 $^{\circ}$ at 50 min under environment of 0$^{\circ}$. 3) The rectal temperature of normal mice with restraint was less than that of adrenalectomized mice (non-restraint) under cold-stress. 4) The rectal temperature of normal and adrenalectomized mice that acclimated under cold stress ($0^{\circ}C$) for 5 and 10 days was usually higher than that of normal and adrenalectomized mice of non-acclimation under environment of $0^{\circ}C$. 5) The tolerance in mice under cold-stress was increased on the acclimtion of cold.

• Journal of Korean Medicine Rehabilitation
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• v.20 no.4
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• pp.147-157
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• 2010

Objectives : The study is performed to investigate the influence of psychological stress on neck muscles tone and heart rate variability(HRV). Methods : This study was carried out with the data from stress response index score(SRI), surface electromyography(sEMG) and HRV. First subjects were divided into two group according to the SRI points. Subjects in group A had points of SRI in which lower than 30 points. Subjects in group B had points of SRI in which higher than 30 points. Then we investigated how to difference of the index of sEMG and HRV according to each groups. Results : In this study, the muscle contraction of both upper trapezius muscle in stress group were higher than non-stress group significantly. Complexity, root mean square of successive differences of R-R intervals(RMSSD), standard deviation difference between adjacent normal to normal intervals(SDSD), high frequency oscillation power(Ln(HF)), normalized HF(Norm HF) in stress group were lower than non-stress group significantly and normalized LF(Norm LF) was higher. Conclusions : This results show that the stress was associated with neck muscle condition and autonomic nervous system.

• The Journal of the Korea Contents Association
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• v.11 no.11
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• pp.221-230
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• 2011

The purpose of this study was to determine whether parenting stress is related to anxiety in children with ADHD. The data were provided by 112 children between the ages of 7 and 9. Forty nine children with a diagnosis of ADHD were recruited through 3 departments of child psychiatry and 63 normal children were recruited from elementary schools from the same city. The Korean version of Parenting Stress Index-Short Form was used to assess parenting stress and the Korean version of the State Trait Anxiety Inventory for Children was used to assess the level of anxiety. The results show that children with ADHD have significantly higher levels of anxiety and parenting stress than normal children. However, no significant differences in parenting stress and anxiety were found across gender, age, and the type of ADHD. Significant correlation was found between trait anxiety and parental distress and between state anxiety and difficult child. Parenting stress didn't significantly influence on anxiety in children with ADHD. Occupational therapist need to consider that the anxiety level of children with ADHD is different from normal children. It is needed for interventions for children with anxiety symptoms and also consultation and intervention for parents with parenting stress.