• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.2
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• pp.317-324
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• 1994

The circulation of Lake Paldang is analysed numerically as an ultimate goal to develop a vehicle predicting the dispersion and concentration of pollutants and sediment flowed into the lake. In finite difference formulation of 2-D depth averaged governing equations. Abbott's 3-time level scheme is employed and for nonlinear terms time centering iteration technique in time and space is used. Model parameters for shear stresses and eddy diffusivities are determined through measured data in and near the lake. Predicted velocities for steady flow are shown to be close to the measured velocities and further improved by taking into account of wind effect. This indicates that the wind effect is needed for proper circulation analysis and it calls for the inclusion of the wind effect. Simulated results of unsteady flow caused by flood inflows and release through Paldang dam are found to characterize the flow features quite well as expected. This implies that the developed model can be used as a tool to analysing the circulation in the lake.

• Geotechnical Engineering
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• v.9 no.1
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• pp.21-30
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• 1993

To know the importance of soil paramters which are used to estimate the deformation and porepressure of soil, the sensitivity for soil parameters in elastic analysis is analyzed. Using the consolidation teat results of several cohesive soils, soil parameters are estimated by back analysis method, and from the parameters the deformations and porepressures of the soil are estimated by elastic analysis, In elastic analysis for soil-deformation and porepressure, the sensitivity for the Young's modulus is large, and the esimation of Young's modulus is more important in pro- portion to the size of stress. Using the measured results during initial short period in small stress, the soil parameters can be correctly estimated by back analysis method. To decrease the iteration number in back analysis and to get the better paramters, the initial measurements in more nodes are required and the more accurate initial measurements are required.

• Clinics in Shoulder and Elbow
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• v.11 no.2
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• pp.82-89
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• 2008

Ideal rotator cuff repair is to maintain high fixation strength and minimize gap formation for optimizing the environment of biologic healing of tendon to bone. Among the current repair techniques, the suture bridge technique is superior to single- or double-row repair in ultimate load to failure, gap formation, restoring anatomical footprint and achieving pressurized contact area. The suture bridge technique also minimizes gap formation and has rotational and torsional resistances allowing early rehabilitation. However, despite superior biomechanical characteristics of the suture bridge technique, there is no evidence that these mechanical advantages result in better clinical outcomes. Furthermore, there is no difference in failure rates between the double-row repair and suture bridge techniques. An appropriate repair technique should be determined based on tear size and pattern and tendon quality.

• Computational Structural Engineering
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• v.8 no.4
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• pp.75-85
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• 1995

The purpose of the present study is to develop a computer program which can be used to analyze prestressed concrete structures containing either bonded or unbonded tendons. To accomplish this, first, the concrete, nonprestressed, and prestressed steels are modeled with cyclic constitutive laws to take into account the various loading effects. Then, the hybrid-type element method is derived to improve the computations capability of stresses and strains, especially for the unbonded tendon. Since it allows one to determine the cross-sectional deformations in an element without any assumptions for its deformed shape, the element length can be much longer than that of the conventional finite element method. In order to achieve such a long element, various integral schemes are examined to implement them into the program. Then, the computational method for prestressing effects is developed consistently with the analytical method for the structure. Finally, analytical studies for actual tests were carried out to verify the program developed in this study.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.305-316
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• 2011

As the building structures are higher and bigger, the high-performance steels of high strength, toughness, and low yield ratio had been required and developed. In this paper the behavior of the moment connection with bolted web and high strength steel was studied by using the finite-element analysis computer program of ABAQUS. The analysis model is based on the test results and the same cyclic load history was applied at the FE(Finite Element) model until it failed in the test. Through the FEA, several indicators hardly measured from the test were acquired. These indicators related to stress and strain were selected from three plastic rotation stages: 0.003 rad, 0.03 rad, and final failure rotation. Specifically, at the final failure stage, the strain indicators producing the full plastic behavior were suggested as a mechanical property for steel.

• Journal of the Korean Geotechnical Society
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• v.28 no.2
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• pp.23-31
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• 2012

The purpose of this study is to analyze earth pressure acting on a circular shaft-tunnel considering arching effect by centrifuge modeling test on sands. The centrifuge testing method provides a way to model an in-situ stress state condition with a stress gradient within a laboratory specimen. A small-scale model of circular shaft-tunnel, which has a real diameter of 6.0 m and height of 15.0 m, was designed and tested twice under 75g-level. Additionally, an effect of excavation was presented by separating two segments of circular shaft wall to find behavioral properties and strength of earth pressure along with excavating ground. The test results were compared with those of the proposed earth pressure equation. The test results showed that earth pressure decreased by about 70% in comparison with existing two-dimensional earth pressure. This fact might be attributed to three-dimensional arching effects.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.56-63
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• 2018

The present study examined the reversal cyclic flexural behavior of walls with jacket section approach for seismic strengthening through forming the boundary elements at both ends of the wall. The prestressed wire ropes were used for the lateral reinforcement to confine the boundary element of the wall. The main parameter investigated was the height of the jacket section for strengthening. The limit height of the strengthening jacket section was determined by comparing the moment distributions between the existing and strengthened walls. Test results showed that the examined jacket section approach was significantly effective in enhancing the flexural resistance of walls, indicating 46% higher stiffness at peak strength and 210% greater work damage indicator, compared with the flexural performance of the unstrengthened wall. The ductility of the strengthened walls was insignificantly affected by the height of the jacket section when the height is greater than twice the wall length. The flexural capacity of the strengthened walls was 22% higher than the predictions obtained using the equivalent stress block specified in ACI 318-14.

• Magazine of the Korea Concrete Institute
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• v.5 no.4
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• pp.179-187
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• 1993

In thls study, cylindrical concrete specimens wth varlous strength levels were tested to lnves tlgate the fatigue behavlor of high strength concrete. Selected test variables welp cornpresslve strength with 4 levels(26 MIPa, 54 MPa, 82 MPa. 103 MPa) and maximum \tress wlth 4 levels (75% 80%, 85%, 95%). A total of 160 specimens(${\phi}100{\times}200mm$) were cdsted fol the test. l'he fatigue llfe was decreased for the hlgher strength concreate. R model fol S N, relationship con sidering the effect of compressive strength, was proposed. In addition, this model included the stram rate effect whlch was modified for the strength level. It was found that the ~rrecoverable stram of normal strength concretc3 was greater than that of high strength concrete However the strain ~ncrease per cycle of load was great for the highcr strength concrete.

• Magazine of the Korea Concrete Institute
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• v.9 no.2
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• pp.167-177
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• 1997

In thtx design of ductile moment -1csist1ng frnmcls (DMRFs) f'ollow~ng the. stlong columnweakbeam design philosophy, it is desirable that the joint and column remain essentiallyelastic in order to insure proper energy dissipation and lateral stability of the structure.Thv joint has been identifid as the "weak link: in DMRFs because any stiffness orstrength deterioration in this region can lead to substantial drifts and the possibility ofcollapse due to t'-delta effects. h3oreove1.. the tngintw is faced with the difficult task ofdetailing an element whose size is determined by theframing members, but \vhich mustresist a set of loads very different from those used in the design of the beams and columns.Four 3 -scale beam-column-slab joint assemblies were designed according to existing cod\ulcornerrequirements of' ACI 318-89. representing perimeter joints of DMRFs with reinforced highstrength concrete. The influence on aseismic behavior of beam-column joints due tomonolithic slab, has been investigated.lab, has been investigated.

• Journal of the Korean Institute of Gas
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• v.3 no.3 s.8
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• pp.58-64
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• 1999

This paper has been analyzed for the stress behavior problems of the ring knot membrane unit using the finite element method about the pitch design of the membrane unit, which is one of the most important parameters in manufacturing of the membrane type LNG storage tanks. The FEM results have been compared those of the existing pitch design length. The safety problem of the ring knot membrane model, which is considered in this study, does not come out any more no matter what the pitch length is used in the extra large LNG storage tanks. But in the case of the membrane for LNG tankers, it is advantageous to design the pitch short because of fatigue strength caused by repeated loadings. Looking at the deformation behaviors of the membrane corrugation, the deformation of the hight in the y direction occurs $15{\~}50\%$ more than that of the width in the z direction. It shows also that the deformation of the membrane with $-162^{\circ}C$ cryogenic temperature is not so great compared with the deformation by hydrostatic pressure.