• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.9 s.114
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• pp.982-989
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• 2006

The centrifugal force acting on a rotating disk creates the in-plane loads in radial and circumferential directions. Application of fiber reinforced composite materials to the rotating disk can satisfy the demand for the increment of its rotating speed. However, the existing researches have been confined to lamina disks. This paper deals with the stress and vibration analysis of rotating laminated composite disks. The maximum strain theory for failure criterion is applied to determine the strength of the laminate disk from which the maximum allowable speed is obtained. Dynamic equation is formulated in order to calculate the natural frequency and critical speed for rotating laminated disks. The Galerkin method is applied to obtain the series solution. The numerical results are given for the cross-ply laminated composite disks.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.2
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• pp.73-85
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• 1995

This study aimes at investigating the applicability of single surface work - hardening model(7, 8) to clayey soils through FEM analysis. The comparison was carried out for the results between numericaL analysis and cubical triaxial tests in which confined stress was applied differently and 3-directional principal stress can be controlled. Furthermore, the results of the numerical analysis were compared with observed values of load test on the 2-dimensional model foundation composed of clayey soils. The agreement between nu- merical and observed values proved to be of high accuracy, which indicates that numeri- cal techniques developed during this study using the model can be used for the prediction of settlement, leteral displacement and pore water pressure of actual soft foundation of clayey soils.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.621-626
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• 1998

In this study, the analytic model of concrete column strengthened with CFS(carbon fiber sheets) for obtaining P-M interaction is presented. Firstly, an algorithm to evaluate accurate behavior of CFS is presented using laminate theory. Stress-strain model of CFS is presented based on the results of this algorithm. Secondly, an algorithm to evaluate stress-strain relationship of concrete column confined with CFS is presented. In order to evaluate the reliability of these algorithms, the results of analysis are compared with experimental data. Lastly, section analysis is performed by using constitutive equations of materials. As a result, P-M interaction curve of the column strengthened is obtained and the strengthening effects of CFs are analyzed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.2
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• pp.119-123
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• 2000

To study the stress response of coho salmon (Oncorhpohus kisutch) during transportation, the stress responses of the fish confined in a container box filled with freshwater or $5{\%{\circ}}$ salt-water were monitored pre and post 10 hours transportation. Changes of cortisol as the first stress indicator, and glucose (GLC), lactate (LAC), triglyceride (TG), cholesterol (CHOL), sodium ($Na^+$), chloride ($Cl^-$), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) as the second stress indicators were compared between the fish in two hauling media. Results showed significantly lower levels of cortisol, GLC, LAC, TG, CHOL and AST in salt-water group than freshwater group, It was shown that using salt-water for transportation could lessen the stress level of the coho salmon.

• Journal of Korean Physical Therapy Science
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• v.10 no.1
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• pp.58-64
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• 2003

The study was done in order to better understand the stress which physical therapist experience during clinical training. Clinical training was not confined to understanding training facts and concepts of physical therapist. The data were collected from November 1 to December 15, 2002 and 129 valid questionnaires were obtained and analyzed. They were analyzed by the percent, frequency, t-test, one-way ANOVA and Pearson Correlation Coefficient. The results of the study were as follows: 1. There were in satisfaction degree of major 42.6% of the subjects was revealed as "satisfied" and in satisfaction degree of clinical training 24.0% of the subjects was revealed as "satisfied". 2. There were much stress in relation of physical therapist was revealed as the most severe stress at a mean 15.98 and environment was revealed as severe stress at a mean 12.94. in role was revealed as the lessor stress at a mean 4.12. 3. The state anxiety degree which physical therapist students experience during clinical training was revealed as "moderate" anxiety. 4. There were significant difference between relation of physical therapist and satisfaction degree of clinical training (p<0.05), between ideal and values of physical therapist and health condition(p<0.05), between relation of tint and satisfaction degree of major(p<0.05), between education the characteristic which it will pull out and satisfaction degree of major(p<0.05), satisfaction degree of clinical training(p<0.05).

• Journal of Korean Society of Steel Construction
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• v.27 no.1
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• pp.31-42
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• 2015

The plastic stress distribution method and the strain compatibility method are the two representative methods to calculate the P-M interaction strength of RCFT (rectangular concrete filled tube) columns. The plastic stress distribution method is approximate while the stress compatibility method should approach the exact solution if accurate constitutive relations of the materials involved are used. Recent study by the authors pointed out that, because of lack of accurate constitutive model for the concrete confined by the rectangular steel tube, no strain compatibility method according to the current structural provisions provides a satisfactory prediction of the P-M interaction strength of RCFT columns under various material combinations. An empirical constitutive model which can capture the stress-strain characteristics of the confined concrete of RCFT columns is proposed based on analyzing extensive exisitng test database. The key idea was to define the concrete crushing strain as a function of steel-to-concrete strength ratio and width-to-thickness ratio of steel tube. It was shown that the proposed model leads to more accurate and more consistent prediction of the P-M interaction strength of RCFT columns under general design conditions.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.892-899
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• 2002

Among the methods for enhancement of load-carrying capacity on flexural concrete member, recently, a concept is being investigated which replaces the steel in a conventional reinforced concrete member with a fiber reinforced polymer(FRP) shell. This study focuses on modeling of the structural behavior of concrete surrounded with FRP shells in flexural bending members. A numerical model of fiber cross-sectional analysis is proposed to predict the stress and deformation state of the FRP shell and concrete. The stress-strain relationship of concrete confined by a FRP shell is formulated to be based on the constitutive law of concrete in multi-axial compressive stress state, in assuming that the compression response is dependent on the radial expansion of the concrete. To describe the FRP shell behavior, equivalent orthotropic properties of in-plane behavior from classical lamination theory are used. The present model is validated to compare with the experiments of 4-point bending tests of FRP shell concrete beam, and has well predicted the moment-curvature relationships of the members, axial and hoop strains in the section, and the enhancement of confinement effect in concrete surrounded by FRP shell.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.221-229
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• 2008

An improved unbonded-type column strengthening procedure using wire rope and T-shaped steel plate units was proposed. Eight strengthened columns and an unstrengthened control column were tested under concentric axial load. The main variables considered were the volume ratio of wire rope and the flange width and configuration of T-shaped steel plates. Axial load capacity and ductility ratio of columns tested were compared with predictions obtained from the equation specified in ACI 318-05 and those of conventionally tied columns tested by Chung et al., respectively. In addition, a mathematical model was proposed to evaluate the complete stress-strain relationship of concrete confined by the wire rope and T-plate units. Test results showed that the axial load capacity and ductility of columns increased with the increase of the volume ratio of wire rope and the flange width of T-plates. In particular, at the same lateral reinforcement index, a much higher ductility ratio was observed in the strengthened columns having the volume ratio of wire rope above 0.0039 than in the tied columns. A mathematical model for the stress-strain relationship of confined concrete using the proposed strengthening procedure is developed. The predicted stress-strain curves were in good agreement with test results.

• Geotechnical Engineering
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• v.5 no.2
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• pp.57-77
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• 1989

This paper describes the design and construction aspects of time-dependent deformation test apparatus for slut.oiling rocks and presents the test results obtained using these apparatus. These tests are modified semi-confined swell test, swell test under uniaxial tension and swell test under biaxial stress. These apparatus measure the time.dependent deformations in three orthogonal directions of the test specimen under simplified field stress conditions. The test results obtained from these test apparatus for the last several years show that these apparatus have performed satisfactorily. The test results show that the time-dependent deformation behaviour of the Queenston shale is cross-anisotropic with higher swelling in the vertical direction (normal to bedding plane) than in horizontal direction (parallel to bedding plane) under free swell condition. The applied stress in one direction suppresses the swelling deformation in that direction as well as that in the orthogonal directions.

• Magazine of the Korea Concrete Institute
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• v.7 no.2
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• pp.146-154
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• 1995

I n this paper, an experimental research was carried out to investigate the confinement effect of spiral reinforcements in concrete column specimens subjected to t.he concentric axial corn pressive loads. Main variables were the compressive strengths of concrete of 27.2, 62.4 and 81.2 MPa, and the spacings of spirals of 120, 60, 40, 30, 25 and 20mm. and the yield strengths of spir als of 451 and 1375MPa, respectively. For the same volumetric ratio and yield strength of spir als, it was shown that the strength increment of confined concrete was almost same regardless of the strength of unconfined concrete, however, the axial stram at maximum stress was decreas ed with increasing of the compressive strength of unconfined concrete.