• Journal of the Korea Concrete Institute
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• v.14 no.2
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• pp.171-179
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• 2002

This paper is a part of research series for the verification of the proposed Moon/Lim design equation. An analytical study was performed to examine the relation between the flexural behavior and the unbonded tendon stress of PSC members. The strain compatibility assumption was used in this study since previous studies showed that the stress variations of tendon had a close relation with the member displacements. The proposed equation has been developed with the same assumption of strain compatibility. Therefore the analytical procedure with the strain compatibility assumption was developed to compute the member displacements of previous tests. Then the analytical results were compared with tests results. The comparison showed that the strain compatibility assumption can be properly applicable to the design equation. Based on the analytical results, the relation between the tendon stress and the member flexural behavior at ultimate was examined. A parametric study also carried out with regard to the member displacements. As results, the parameters used for the proposed equation were proven to be proper for the computation of tendon stress.

• KCI Concrete Journal
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• v.12 no.2
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• pp.55-72
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• 2000

This paper proposes a mechanical model to describe the load-deformation responses of the reinforced concrete plate members under service load state. An Analytical method is introduced on the basis of the rotating crack model which considers equilibrium, compatibility conditions, load-strain relationship of cracked member, and constitutive law for materials. The tension stiffening effect in reinforced concrete structures is taken into account by the average tensile stress-strain relationship from the load-strain relationship for the cracked member and the constitutive law for material. The strain compatibility is used to find out the crack direction because the crack direction is an unknown variable in the equilibrium and compatibility conditions. The proposed theory is verified by the numerous experimental data such as the crack direction, moment-steel strain relationship, moment-crack width relationship. The present paper can provide some basis for the provision of the definition of serviceability for plate structures of which reinforcements are deviated from the principal stresses, because the present code defines the serviceability by the deflection, crack control, vibration and fatigue basically for the skeletal members. The proposed theory is applicable to predict the service load state behavior of a variety of reinforced concrete plate structures such as skew slab bridges, the deck of skew girder bridges.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.101-110
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• 2015

Recently, nine $1397{\times}1397{\times}178mm$ RC panels were tested under in-plane pure-shear monotonic loading condition using the Panel Element Tester by Hsu (1997, ACI). By combining the equilibrium, compatibility, and the softened stress-strain relationship of concrete in biaxial state, Modern Truss Model (MCFT, RA-STM) are capable of producing the nonlinear analysis of RC membrane panel through the complicated trial-and-error method with double loop. In this paper, an efficient algorithm with one loop is proposed for the refined Mohr compatibility Method based on the strut-tie failure criteria. This algorithm can be speedy calculated to analyze the shear history of RC membrane element using the results of Hsu test. The results indicate that the response of shear deformation energy at Big Bang of shear strain significantly influenced by the principal compressive stress-strain (crushing failure).

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1580-1587
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• 2005

To calculate the long-term allowable strength of geosynthetic reinforcement, replacement method was recommended. The isochronous creep curve by S. Turner was used to define the relation between creep strain and allowable strength. In isochronous curve at given time, one can read the allowable strength at allowable creep strain. The allowable strain gets from specification by directors or manufacturers according to the allowable displacement of reinforced structures. The allowable strength can be determined in relation to the allowable horizontal displacement each structures case by case. The effect of install damage on isochronous behaviors of geosynthetic reinforcement was little. In previous study, install damage increase the creep strain slightly. And the degradation was not identified. But it is supposed that degradation increase the creep strain. In conclusion, The recommended model to determine long-term allowable strength of geosynthetic reinforcements considering tensile deformation of reinforcement and soil is fit for proper, correct and economic design for reinforced earth walls.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1810-1818
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• 1996

A new finite elemetn approach is introduced for direct prediction of bland shapes and strain distributions from desired final shapes in sheet metal forming. The approach deals with the geometric compatibility of finite elements, plastic deformation theory, minimization of plastic work with constraints, and a proper initial guess. The algorithm developed is applied to cylindrical cup drawing, square cup drawing, and fron fender forming to confirm its validity by demonstratin reasonable accurate numerical results of each problems. Rapid calculation with this algorithm enables easy determination of various process variables for design of sheet metal forming process.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.175-181
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• 2010

The three truss models(equilibrium truss model, Mohr compatibility truss model, and the soften truss model) based on a rotating angle is called the rotating-angle model. The three rotating-angle models have a common weakness: they are incapable of predicting the so-called "contribution of concrete". To take into account this "contribution of concrete", the modern truss model(MCFT, STM) treats a cracked reinforced concrete element as a continuous material. By combining the equilibrium, compatibility, and the softened stress-strain relationship of concrete in biaxial state, MTM is capable of producing the nonlinear analysis of reinforced concrete structures composed of membrane element. In this paper, an efficient algorithm is proposed for the solution of proposed model incorporated with failure criteria. This algorithm is used to analyze the behavior of reinforced membrane element using the results of Hsu test.

• Asian Journal of Turfgrass Science
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• v.12 no.1
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• pp.23-30
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• 1998

174 isolates of soil microorganisms were isolated from E-golf club from Apr.1997 through Oct. 1997. And 27 strains of them were selected through the inhihition test of mycelial growth. In the same period, soil-borne diesease pathogens, "Rhizoctonia", causing Large patch, Brown patch, Spring dead spot, and Yellow patch were isolated from the diseased areas in E-golf and S-golf club. The antagonistic activity of the strains against the pathogens was tested to select the excel-lent antagonists. In contact with the fungicides, the survivability of the antagonists was tested to assess the compatibility of the antagonists with the pesticides. The results were as follows: 1.Suppression of Rhizoctonia by Antagonists. Antagonistic activity of 27 strains against the pathogens was: tested in vitro. In the result, 3 isolates(B-7, B-15, B-41) of bacteria and 2 isolates(F-5, F-47) of fungi were superior to the rest. 2.Compatibility of the antagonists: with the fungicides: With 13 kinds of pesticides widely using Golf Club, Compatibility of 5 antagonists: were finally tested to select the strains: that mostly survived in contact with pesticides. In the results:, two of five strains: were selected : one strain was bacteria B-15, the other strain was fungi F-47. 24h after the mixing with pesticides:, these two strains were shown to survive at 90% level and these were identified as Bacillus and Trichoderma, respectively. And the most compatible pesticides: with the antagonists were shown to Polytoxin-D thirarn(s:urvivability 99.4%) and Validamycin-A (survivability 98.6%). Keywords:Antagonist, Large Patch, Trichoderma, Compatibility, Fungicide.Fungicide.

• Journal of Korean Association for Spatial Structures
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• v.17 no.4
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• pp.149-157
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• 2017

An innovative analysis method is proposed in this paper for the determination of ultimate resistance of prestressed concrete beams. The proposed method can be applied to simply supported or continuous beams in a unified manner whether structure and external loads are symmetric or not. Through the iterative nonlinear strain compatibility solutions, this method can also be applied to the non-prismatic section/un-symmetrical composite structures under moving load. The conventional studies have used the failure criteria when the strain of concrete reaches 0.003. However compared with bonded case, the value of strain in the reinforcement is much smaller than bonded case, thus, unbonded prestressed cases show compressive failure mode. It is shown that the proposed method gives acceptable results within 5% error compared with the prior experimental results. It can be shown that the proposed method can reach the solution much faster than typical three-dimensional finite element analysis for the same problem. This method is applicable to the existing unbonded prestressed members where deterioration has occurred leading to the reduced ultimate resistance or safety. In all, the proposed procedure can be applied to the design and analysis of newly constructed structures, as well as the risk assessment of rehabilitated structures.

• Structural Engineering and Mechanics
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• v.2 no.1
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• pp.1-16
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• 1994

A unified theory has recently been developed for reinforced concrete structures (Hsu 1993), subjected to the four basic actions - bending, axial load, shear and torsion. The theory has five components, namely, the struts-and-ties model, the equilibrium (or plasticity) truss model, the Bernoulli compatibility truss model, the Mohr compatibility truss model and the softened truss model. Because the last three models can satisfy the stress equilibrium, the strain compatibility and the constitutive laws of materials, they can predict not only the strength, but also the load-deformation history of a member. In this paper the five models are summarized to illustrate their intrinsic consistency.

• 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.