• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.145-146
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• 2020

This study investigated the performance evaluation of polymer cement mortar for repairing concrete structures using calcium nitrite(Ca(NO₂)₂) and CO₂ nano-bubble mixing water to develop section-restoration methods for the repair and reinforcement of cracks. The evaluation items were strength and microstructure analysis at 28 days of age according to the change in the amount of calcium nitrite and the use of CO₂ nano-bubble water. As a result of the experiment, it was confirmed that the performance of polymer cement mortar for repairing concrete structures was improved by the generation of nitrite-based hydration products when calcium nitrite and CO₂ nano-bubble water were used.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.239-246
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• 2017

RC(Reinforced Concrete) structures can keep their performance during intended service life through initial service life and extension of the life through repairs. In the deterministic repairing method, cost and the related $CO_2$ emission increase with step-shaped escalation, however continuous results can be obtained through probabilistic repairing technique, and this is capable of reducing $CO_2$ emission through $CO_2$ absorption. In the work, repairing timing and $CO_2$ emission/absorption are evaluated based on the different methods like deterministic and probabilistic manner. The probabilistic technique considering $CO_2$ absorption with carbonation progress is evaluated to be very effective to reduction of $CO_2$ emission through extension of initial and additional service life due to repairs. When the variations of the service life from initial construction and repair material can be determined, the proposed technique can contribute to reduction of cost and $CO_2$ with decreasing repairing number.

• Advances in concrete construction
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• v.8 no.2
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• pp.91-100
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• 2019

In this paper three damaged exterior RC beam-column joints made of recycled aggregate concrete (RAC) were repaired. The aim of the study was to restore back the lost capacity of the beam-column joint to the original state or more. A relatively cheap material locally available galvanized steel welded wire mesh (GSWWM) of grid size 25 mm was used to confine the damaged region and then jacketed with cement mortar. Repaired specimens were also subjected to similar cyclic displacement as those of unrepaired specimens. Seismic parameters such as load carrying capacity, ductility, energy dissipation, stiffness degradation etc. were analyzed. Results show that repaired specimens exhibited better seismic performance and hence the adopted repairing strategies could be considered as satisfactory. These findings would be helpful to the field engineers to adopt a suitable rapid and cost efficient repairing technique for restoring the damaged frame structural joints for post earthquake usage.

• Earthquakes and Structures
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• v.14 no.5
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• pp.379-388
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• 2018

This study aims to identify the effect of both longitudinal reinforcement details and damage level on making a decision of repairing pre-damaged bridge columns using basalt fiber reinforced polymer (BFRP) jackets. Two RC bridge columns with improper details of the longitudinal and/or transverse reinforcement were tested under the effect of a constant axial load and increasing lateral cyclic loading. Test results showed that the lap-splice column exhibited an inferior performance where it showed rapid degradation of strength before achieving the theoretical strength and its deformation capacity was limited; however, quick restoration is possible through a suitable rehabilitation technique. On the other hand, expensive repair or even complete replacement could be the decision for the column with the confinement failure mode. After that, a rehabilitation technique using external BFRP jacket was adopted. Performance-based design details guaranteeing the enhancement in the inelastic performance of both damaged columns were addressed and defined. Test results of the repaired columns confirmed that both reparability and the required repairing time of damage structures are dependent on the reinforcement details at the plastic hinge zone. Furthermore, lap-splice of longitudinal reinforcement could be applied as a key design-tool controlling reparability and restorability of RC structures after massive actions.

• Journal of Wetlands Research
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• v.19 no.1
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• pp.63-68
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• 2017

Maintenance of sewer pipe process sewer pipe repairing process is necessary for deterioration of sewer pipe. In this research, analysis on performance (strength and twist strain) of eco-friendly and even expanded liner process using glass fiber and twist prevention band. As a results, tensile strength, bending strength and failure load is increased after the sewer pipe repairing process than advanced research results. And sewer pipe after the this process obtained advantage of prevention of twist strain and economic. After the this research, sewer pipe repairing process using glass fiber and twist prevention band could be suggest the eco-friendly and effective sewer pipe repairing process.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.372-378
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• 2020

In this study, an experiment was conducted on the development and performance of self-propelled vehicles to repair defects in concrete sewage pipes. The self-propelled vehicle for a non-excavation repair for the sewage pipe defects was developed in consideration of the performance of the driving system, the feasibility of the repair unit, and the transportation of repair materials. In order to evaluate the performance of the developed self-propelled vehicle, a repair test was performed by simulating a defect at a connection between the main pipe and extruded one. The main sewage pipe was meade of concrete and its diameter was 500mm. Thereafter, watertightness performance was evaluated on the leakage at the repaired part. For watertightness performance, both ends of concrete sewage pipe and connected one was inserted by plugs, and then water was injected. The amount of leakage water measurement was 0.07L/㎡, indicating a value less than 0.2L/㎡ of the allowable leakage amount. Therefore, test results indicated that the self-propelled vehicle developed in this study exhibited excellent maintenance performance for repairing the sewage pipes.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.513-516
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• 1999

The objective of this study is to evaluate the performance of the repaired structural walls which were severly damaged. After damaging the wall specimens by experimental test, the walls were repaired and retested to destruction. For the repairing the severly damaged walls, new concrete and new reinforcing bar are replaced with cracked concrete and the buckled reinforcing bar, respectively. The performance of repaired wall specimens are compared with that of undamaged walls.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.285-288
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• 2005

This paper is an experimental study on applicability of repairing mortar using multi-functional slag aggregate. In this study, automatic construction machinery system were adapted, and their performance were evaluated by the using of those systems. In order to verify the effect of multi-functional aggregate, two kinds of aggregate were used and compared of their physical properties. The results indicate that multi-functional aggregate appears good physical properties such as durability, permeability coefficient.

• Journal of Information Processing Systems
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• v.18 no.5
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• pp.628-636
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• 2022

Automatic program repair (APR) techniques focus on automatically repairing bugs in programs and providing correct patches for developers, which have been investigated for decades. However, most studies have limitations in repairing complex bugs. To overcome these limitations, we developed an approach that augments datasets by utilizing token tagging and applying machine learning techniques for APR. First, to alleviate the data insufficiency problem, we augmented datasets by extracting all the methods (buggy and non-buggy methods) in the program source code and conducting token tagging on non-buggy methods. Second, we fed the preprocessed code into the model as an input for training. Finally, we evaluated the performance of the proposed approach by comparing it with the baselines. The results show that the proposed approach is efficient for augmenting datasets using token tagging and is promising for APR.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.355-360
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• 1995

A series of 15 reinforced concrete beams was tested to evaluate the flexural performance of the repaired RC beams. the key parameters for this study were the repair materials, polymer/cementitious materials, in addition to the strengthening material, steel plates and carbon fiber sheets. The repaired specimens failed by a typical flexural mode. showing minor interface failure. The results show that epoxy, polyester resins and latex modified cementitous mortars are effective for repairing the concrete beams. However, the flexural preformance of the strengthened beams are varied depending on the repaired materal.