• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.200-201
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• 2013

This study is interested in manufacturing the concrete surface impregnants including tetra ethyl ortho silicate, alkali silicate for the repair of the exposed concrete and the color concrete requiring the advanced function in view of the concrete appearance. The surface layer change and porosity properties was tested for the review of application. The result of this study show that the effective silicate are tetra ethyl ortho silicate and alkali silicate t. The adhesion in tension is slightly increased but the reinforcement of concrete substrate is slight. So, the concrete impregnant of this study is more desirable for the improvement of durability rather than the reinforcement.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.1
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• pp.24-31
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• 2011

In order to measure corrosion level of reinforcement rebar in RC structures, non-destructive test methods which are concrete surface current density method and infrared thermographic technique were employed to measure corrosion levels. Experimental test parameters were various levels of corrosion states(0, 1, 3, 5, 7% of weight loss) and concrete cover depth(30 mm, 40 mm) and two different reinforcing rebar arrangements. The larger amount of concrete surface current density, the higher corrosion level in reinforcement rebar. The laboratory conditions which are ambient temperature and humidity have negligible effect on the infrared thermographical data. After analysis of current density and temperature distribution from concrete surface, corrosion level of reinforcement rebar embedded in concrete can be measured qualitatively based on the amount of electric current and heat flux.

• Journal of the Korean Geosynthetics Society
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• v.8 no.2
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• pp.11-20
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• 2009

This study, as basic research which was intended to develope the surface reinforcement method using reinforcement material which is applicable to very soft ground in Korea, was aimed at proposing the design parameter for the surface ground improvement method. To that end, a wide width tensile test using geotextile, geogrid and steel bar (substitute for bamboo) and 21 kinds of the laboratory model tests with the end restraint conditions of the reinforcement that comprises the constrained and partially constrained (3 types) conditions were conducted. Moreover, a new procedure was proposed to take into account the effect of the stiffness of Reinforce materials on bearing capacity theory of Surface Reinforcement Method for Soft Ground.

• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.85-92
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• 2008

It is necessary to develop a rational design method for surface reinforcement of very soft ground because most current design works rely on merely crude empirical correlations. In this paper, the mechanical behavior of very soft ground that is surficially reinforced was investigated with the aid of a series of numerical analyses. Several material properties of each dredged soft ground, reinforcement and backfill sand mat have been exercised in the numerical analysis. The result of numerical analysis was compared with those of the laboratory model test. Through the matching process between the numerical and experimental result, it is possible to determine representative material properties of the dredged soft ground, reinforcements and backfill sand mat. These verified material properties permit to evaluate the effect of the stiffness of reinforcement and the thickness of sand mat on the overall deformation of the reinforced soft ground.

• Structural Engineering and Mechanics
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• v.53 no.6
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• pp.1183-1200
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• 2015

Reinforcement corrosion can cause serious safety deterioration to aging concrete structures exposed in aggressive environments. This paper presents an approach for reliability analyses of deteriorating reinforced concrete structures affected by reinforcement corrosion on the basis of the representative symptoms identified during the deterioration process. The concrete cracking growth and rebar bond strength evolution due to reinforcement corrosion are chosen as key symptoms for the performance deterioration of concrete structures. The crack width at concrete cover surface largely depends on the corrosion penetration of rebar due to the expansive rust layer at the bond interface generated by reinforcement corrosion. The bond strength of rebar in the concrete correlates well with concrete crack width and decays steadily with crack width growth. The estimates of cracking development and bond strength deterioration are examined by experimental data available from various sources, and then matched with symptom-based lifetime Weibull model. The symptom reliability and remaining useful life are predicted from the predictive lifetime Weibull model for deteriorating concrete structures. Finally, a numerical example is provided to demonstrate the applicability of the proposed approach for forecasting the performance of concrete structures subject to reinforcement corrosion. The results show that the corrosion rate has significant impact on the reliability associated with serviceability and load bearing capacity of reinforced concrete structures during their service life.

• Journal of Welding and Joining
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• v.15 no.1
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• pp.55-65
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• 1997

The stress intensity factor has been calculated for the cracked plate subjected to remote normal stress and reinforced with a plate by symmetric spot welding. The solution was based on displacement compatibility condition between the cracked sheet and the reinforcement plate. It is shown that the results from the derived equation for stress intensity factor were agreed with previous solutions. The reinforcement effect gets better as a joining spot is closer to the crack tip and the other joining spots become nearer to the crack surface.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.337-340
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• 2006

Utilize several kinds of reinforcement fibers to control workability and surface crack in occasion of mortar used in dilapidated concrete section repair public law. Polypropylene or poly vinyl alcohol that is hydrophilic fiber etc. is used much usually with this reinforcement fiber. Reinforcement fiber does important action that control crack that enhances coherence between material and happens at dry contraction. In this study, wished to use Sepiorite that inorganic materials and affinity such as cement are excellent nature inorganic world fiber and improve repair mortar performance. In this study, as reinforcement fiber, wished to grasp physical characteristics that uses Sepioraiteu and happens this time and grasp application possibility of concrete's repair mortar.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.474-480
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• 2012

Diagnostic tests were performed on two high voltage(HV) motor stator windings. These tests included the measurement of insulation resistance, polarization index, AC current, dissipation factor($tan{\delta}$) and partial discharge(PD) magnitude. Surface contamination of HV motor stator windings has an effect on the AC current and $tan{\delta}$. When the stator windings were finished cleaning and insulation reinforcement, the increase rate of AC current(${\Delta}I$) and dissipation factor(${\Delta}tan{\delta}$) were very small compared to those before cleaning. However, the PD magnitude remained the same. These tests show that cleaning and insulation reinforcement of HV motor stator windings can reduce the insulation failure.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.393-396
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• 2008

The purpose of this paper is to find out quantitatively the relationship between the surface shape and the mechanical properties of corroded reinforcement. Three-dimensional measurements were carried out on the surface shape of variously corroded reinforcements and parameters expressing the characteristics of the shape, which included the maximum decrement of sectional area of reinforcement, its distribution along the axis. It was investigated that which parameters could correspond to the mechanical properties of corroded reinforcement and it was confirmed that the maximum decrement of sectional area of reinforcement could express the mechanical properties most appropriately. Finally, this paper proposes a constitutive model of corroded reinforcement for analyzing the structural behavior of reinforced concrete structures considering the localized corrosion of by finite element method.

• Tunnel and Underground Space
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• v.14 no.1
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• pp.43-53
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• 2004

In this study, scaled-model tests were performed to investigate the effect of underground openings on the stability of surface structure around the abandoned coal mine areas. Four types of test models which had respectively different depths of openings and different ground reinforcement conditions were introduced, where the modelling materials were the mixture of sand, plaster and water. The model with deep openings were turned out more stable to the structure than the model with shallow ones, because the crack-initiating pressure of the former was 2.5 times as much as that of the latter. The models with ground reinforcement were also fumed out more stable than the model without reinforcement, because the crack-initiating pressure of the former was 2.4 times as much as that of the latter. Subsidence profiles were analysed to find the characteristics of slope and curvature, and the model with large reinforcement were turned out the most stable.