• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.113-116
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• 2005

In this study, in order to. investigate the effectiveness af tuned liquid damper (TLD) for the seismic performance enhancement af the existing reinforced concrete (RC) apartment structure which is nat seismically designed, shaking table test was conducted for the small scale five stary RC structure with TLD. TLD model was constructed to. have the frequency tuned to. the first modal frequency af the structure, $2\%$ mass ratio. af the first modal mass, and 0.08 liquid depth ratio. White noise with $0.2\~5Hz$ frequency bandwidth tests were performed using the shaking table at Korea Institute af Machinery and Materials, and the displacement and absolute acceleration af each floor were measured. Test results indicate that mare than $30\%$ seismic responses reduction can be achieved using TLD for RC structure under white noise.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.403-413
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• 2017

Residual axial capacity from numerical analysis was widely used as a critical indicator for damage assessment of reinforced concrete (RC) columns subjected to blast loads. However, the convergence of the numerical result was generally based on the displacement response, which might not necessarily generate the correct post-blast results in case that the strain softening behavior of concrete was considered. In this paper, two widely used concrete models are adopted for post-blast analysis of a RC column under blast loading, while the calculated results show a pathological mesh size dependence even though the displacement response is converged. As a consequence, a nonlocal integral formulation is implemented in a concrete damage model to ensure mesh size independent objectivity of the local and global responses. Two numerical examples, one to a RC column with strain softening response and the other one to a RC column with post-blast response, are conducted by the nonlocal damage model, and the results indicate that both the two cases obtain objective response in the post-peak stage.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.523-524
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• 2009

This study focused on possibility of new optimized durability design for deteriorated RC structure's repairing. New optimized durability design adopted Life Cycle Assessment as sustainability index.

• Corrosion Science and Technology
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• v.4 no.5
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• pp.171-177
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• 2005

A comprehensive framework for numerical simulation of time-dependent performance change of reinforced concrete (RC) structures subjected to chloride attack is presented in this paper. The system is composed of simplified computational models for transport of moisture and chloride ions in concrete pore structure and crack, corrosion of reinforcement in concrete and mechanical behavior of RC member with reinforcement corrosion. Service-life of RC structures under various conditions is calculated.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.851-856
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• 1998

In recent years, glassfibers have been used for strengthening in RC structure because of low material cost and easy repairing work. The purpose of this study is to experimentally and analytically investigate the effect of glassfibers for enhancing the capacity of RC structure. The result shows that yield and ultimate strength of RC beam with glassfibers are increased by approximate 13% and 26%, comparing with those for RC beam without glassfibers. It has been observed from the test that fatigue behaviors of RC beam with glassfibers have been significantly and large improved comparing with those for RC beam without glassfibers.

• Journal of Power Electronics
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• v.17 no.1
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• pp.172-180
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• 2017

The repetitive control (RC) strategy is widely used in AC power systems because of its high performance in tracking period signal and suppressing steady-state error. However, the dynamic response of RC is determined by the fundamental period delay $T_0$ existing in the internal model. In the current study, a ($nk{\pm}i$)-order harmonic RC structure is proposed to improve dynamic performance. The proposed structure has less data memory and can improve the tracking speed by n/2 times. $T_0$ proves the effectiveness of the ($nk{\pm}i$)-order RC strategy. The simulation and experiments of ($6k{\pm}1$)-order and ($4k{\pm}1$)-order RC strategy used in the voltage source inverter is conducted in this study to control the harmonic current source, which shows the validity and advantages of the proposed structure.

• Structural Engineering and Mechanics
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• v.91 no.4
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• pp.369-382
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• 2024

The earthquake loss assessment framework of ductile reinforced concrete (or RC) frame using component-performance -based methodology was studied in this paper. The elasto-plastic rotation angle was used as the damage indicator of structural component, and the damage-to-loss model was proposed on the basis of the deformation indicator of structural component. Dynamic instability during incremental dynamic analysis was taken as collapse criterion, and column failure was taken as criterion that structure has to be demolished. Expected earthquake losses of low-rise, mid-rise and high-rise RC frames were discussed. The expected earthquake loss encompassed collapse loss, demolition loss and repair loss. Furthermore, component groups of RC frame were divided into structural components, nonstructural components and rugged components. The results indicate that ductile RC frame is more likely to be demolished than collapse, especially in low-rise and mid-rise RC frames. Furthermore, the less collapse margin ratio the structure has, the more demolition probability the structure will suffer under rare earthquake. The demolition share of total earthquake loss might be more prominent than repair share and collapse share in ductile RC frame.

• Multiscale and Multiphysics Mechanics
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• v.1 no.2
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• pp.143-156
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• 2016

Reinforced concrete (RC) structures require advanced analysis techniques for better estimation of their seismic responses, especially in the case of exhibiting complex three-dimensional coupling of torsional and flexural behaviors. This study focuses on validating a numerical approach for evaluating the seismic response of a three-dimensional unsymmetrical RC structure through the participation in the SMART 2013 international benchmark program. The benchmark program provides material properties, detailed drawings of the RC structure, and input ground motions for the seismic response evaluation. In this study, nonlinear constitutive models of concrete and rebar were formed and local tests were conducted to verify the constitutive models in finite element analysis. Elastic calibration of the finite element model of the SMART 2013 RC structure was performed by comparing numerical and experimental results in modal and linear time history analyses. Using the calibrated model, nonlinear earthquake analysis and seismic fragility analysis were performed to estimate the behavior and vulnerability of the RC structure with various ground motions.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.269-272
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• 2006

Chloride ion diffusion is the most important thing of occuring deterioration in RC structure. So it is important to decide the precise chloride ion diffusion coefficient in order to predict the durability life in RC structure. The purpose of this study is to analyze the established data, which are restricted by chloride diffusion coefficient, and to calculate chloride ion diffusion coefficient using RCPT test. To examine the prediction of the concrete structure durability by an FEM analysis and the chloride diffusion coefficient as a variable. Each surface finishing materials were effective on the increment of chloride penetration resistance, but showed a little different effect depending on the type of surface finishing material.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.32-33
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• 2015

As the importance of maintenance of reinforced concrete structure recently has emerged, the attention of durability of structure has been increasing. There are many studies about durability decline especially due to the carbonation. In order to study carbonation progress after surface repair of carbonated concrete, each carbonation penetration velocity from different repair materials of concrete structure is compared through the experiment of carbonation accelerating CO₂ concentration to 100%. As carbonation infiltration progress is predicted through this study, the counterplan of service life evaluation will be prepared on selection of repair materials of concrete structure.