• Proceedings of the KSME Conference
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• 2008.11a
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• pp.668-673
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• 2008

In this paper, we developed a physically-based micromechanical model for inelastic deformation of ceramic powders. The aggregate response of ceramic particles was modeled using the two-surface yield function which considered the shear-induced dilatancy caused by friction, rolling resistance and cohesion between powder particles and consolidation caused by plastic deformation of powder themselves under high compression. The constitutive equations were implemented into the user-subroutine VUMAT of finite element program ABAQUS/Explicit. The material parameters in the constitutive model were identified by calibrating the model to reproduce data from triaxial compression tests and simple compression tests. The density distribution obtained by using the proposed model was in good quantitative agreement with the experimental results of the triaxial compression and cold isostaic compression as well.

• Computers and Concrete
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• v.7 no.2
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• pp.87-102
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• 2010

This paper discusses new capabilities developed for the Virtual Penetration Laboratory (VPL) software package to address the challenges of determining Penetration Resistance (PR) equations for concrete materials. Specifically, the paper introduces a three-invariant concrete constitutive model recently developed by the authors. The Advanced Fundamental Concrete (AFC) model was developed to provide a fast-running predictive model to simulate the behavior of concrete and other high-strength geologic materials. The Continuous Evolutionary Algorithms (CEA) automatic fitting algorithms used to fit the new model are discussed, and then examples are presented to demonstrate the effectiveness of the new AFC model. Finally, the AFC model in conjunction with the VPL software package is used to develop a PR equation for a concrete material.

• YAKHAK HOEJI
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• v.50 no.3
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• pp.199-203
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• 2006

A new type of macrolides, lincosamides and streptogramin B antibiotics (MLS) resistance, showing the characteristic phenotype growing within the inhibition zone area around the clindamycin disk, was identified among clinically isolated Staphylococcus aureus. We named the phenotype as MLS resistance with foggy-D shape (fMLS). The average frequency of MLS isolates was 9%. All of fMLS isolates have only erm(A) for the resistance determinant. The growth pattern of the challenged MLS isolate looks intermediate phase between the patterns of inducible MLS resistance and constitutive MLS resistance.

• Steel and Composite Structures
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• v.46 no.4
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• pp.451-469
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• 2023

The use of precast hollow-core slabs (PCHCS) in civil construction has been increasing due to the speed of execution and reduction in the weight of flooring systems. However, in the literature there are no studies that present a finite element model (FEM) to predict the load-slip relationship behavior of pushout tests, considering headed stud shear connector and PCHCS placed at the upper flange of the downstand steel profile. Thus, the present paper aims to develop a FEM, which is based on tests to fill this gap. For this task, geometrical non-linear analyses are carried out in the ABAQUS software. The FEM is calibrated by sensitivity analyses, considering different types of analysis, the friction coefficient at the steel-concrete interface, as well as the constitutive model of the headed stud shear connector. Subsequently, a parametric study is performed to assess the influence of the number of connector lines, type of filling and height of the PCHCS. The results are compared with analytical models that predict the headed stud resistance. In total, 158 finite element models are processed. It was concluded that the dynamic implicit analysis (quasi-static) showed better convergence of the equilibrium trajectory when compared to the static analysis, such as arc-length method. The friction coefficient value of 0.5 was indicated to predict the load-slip relationship behavior of all models investigated. The headed stud shear connector rupture was verified for the constitutive model capable of representing the fracture in the stress-strain relationship. Regarding the number of connector lines, there was an average increase of 108% in the resistance of the structure for models with two lines of connectors compared to the use of only one. The type of filling of the hollow core slab that presented the best results was the partial filling. Finally, the greater the height of the PCHCS, the greater the resistance of the headed stud.

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.10a
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• pp.154-155
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• 2001

Cyclooxygenase-2 (COX-2) is an inducible enzyme expressed in response to a variety of proinflammatory agents and cytokines. COX-2 expression has been shown to be elevated in several different types of human cancer. The presence of oncogenic ras has been associated with constitutive induction of COX-2 in certain H-ras transformed cells, and COX-2 overexpression confers resistance to apoptosis.(omitted)

• Geomechanics and Engineering
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• v.5 no.2
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• pp.119-142
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• 2013

Pile load tests using Osterberg cells (O-cell) were conducted on cast-in-place concrete piles founded in oil sand fill and in situ oil sand at an industrial plant site in Fort McMurray, Alberta, Canada. Interpreted pile test results show that very high pile shaft resistance (with the Bjerrum-Burland or Beta coefficient of 2.5-4.5) against oil sand could be mobilized at small relative displacements of 2-3% of shaft diameter. Finite element simulations based on linear elastic and elasto-plastic models for oil sand materials were used to analyze the pile load test measurements. Two constitutive models yield comparable top-down load versus pile head displacement curves, but very different behaviour in mobilization of pile shaft and end bearing resistances. The elasto-plastic model produces more consistent matching in both pile shaft and end bearing resistances whereas the linear elastic under- and over-predicts the shaft and end bearing resistances, respectively. The mobilization of high shaft resistance in oil sand under pile load is attributed to the very dense and interlocked structure of oil sand which results in high matrix stiffness, high friction angle, and high shear dilation.

• The Journal of Korean Society of Virology
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• v.28 no.4
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• pp.295-302
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• 1998

The RNA genome of poliovirus encodes a long polyprotein precursor and this polyprotein is cleaved proteolytically by viral protease to yield mature proteins. The mature proteins derived from the P1 polyprotein precursor are the component of capsids. To further delineate the process of capsid assembly and encapsidation, in a first attempt, a cell line which expresses the authentic P1 polyprotein was established. CV-1 cells were transfected with the pRCRSVS1P1 plasmid DNA which contains 5'ncr sequences, whole authentic capsid gene of poliovirus and neomycin resistance gene. These cells were treated with G418 for 3 months, and eventually G418 resistant cells were selected and formed colonies. Each colony was picked and grown in the media containing G418. DNA analysis indicated that 1 of 13 neomycin resistant cell lines (R2-18) contains whole poliovirus P1 capsid gene segment which was incorporated into the genome. Immuneprecipitation of cell lysates with sera from rabbit immunized with inactivateded Sabin type 1 particles demonstrated the constitutive expression of the poliovirus P1 capsid protein from R2-18.

• Geomechanics and Engineering
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• v.29 no.2
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• pp.171-182
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• 2022

Reusing the used pile has not yet been implemented due to the unpredictability of the bearing capacity evolution. This paper presents an analytic approach to estimate the sides shear setup after the dissipation of pore pressure. Long-term evolution of adjacent soil is simulated by viscoelastic-plastic constitutive model. Then, an innovative concept of quasi-overconsolidation is proposed to estimate the strength changes of surrounding soil. Total stress method (α method) is employed to evaluate the long term bearing capacity. Measured data of test piles in Louisiana and semi-logarithmic time function are cited to validate the effectiveness of the presented method. Comparisons illustrate that the presented approach gives a reasonably prediction of the side shear setup. Both the presented method and experiment show the shaft resistance increase by 30%-50%, and this highlight the potential benefit of piles reutilization.

• Journal of the Korean Geotechnical Society
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• v.36 no.6
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• pp.35-46
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• 2020

The input parameters for numerical simulation of the liquefaction phenomenon need to be properly evaluated from laboratory and field tests, which are difficult to be performed in practical situations. In this study, the numerical simulation of the cyclic direct simple shear test was performed to analyze the applicability of Finn and PM4Sand models among the constitutive models for liquefaction simulation. The analysis results showed that the Finn model properly predicted the time when the excess pore water pressure reached the maximum, but failed to simulate the pore pressure response and the stress-strain behavior of post-liquefaction. On the other hand, the PM4Sand model properly simulated those behaviors of the post liquefaction. Finally, the evaluation procedure and the equations of the input parameters in the PM4Sand model were developed to mach the liquefaction cyclic resistance ratio corresponding to design conditions.

• Structural Engineering and Mechanics
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• v.61 no.5
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• pp.577-592
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• 2017

A computing procedure is presented to predict the ultimate behavior of prestressed beams under torsion. This computing procedure is based on an extension of the Variable Angle Truss-Model (VATM) to cover both longitudinal and transversal prestressed beams. Several constitutive relationships are tested to model the behavior of the concrete in compression in the struts and the behavior of the reinforcement in tension (both ordinary and prestress). The theoretical predictions of the maximum torque and corresponding twist are compared with some results from reported tests and with the predictions obtained from some codes of practice. One of the tested combinations of the relationships for the materials was found to give simultaneously the best predictions for the resistance torque and the corresponding twist of prestressed beams under torsion. When compared with the predictions from some codes of practice, the theoretical model which incorporates the referred combination of the relationships provides best values for the torsional strength and leads to more optimized designs.