• Journal of the Korea Concrete Institute
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• v.16 no.1 s.79
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• pp.88-93
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• 2004

The objective of this study was to investigate applicability of epoxy injection method to cracked RC beams and structural behavior of repaired RC beams considering pre-loading conditions. For this purpose, five test beams were fabricated under two experimental variables. The main variables of this experimental study were pre-loading conditions and repair methods. The two pre-loading conditions were selected as $70\%$ and $90\%$ of nominal strength and the repair methods were to repair the cracked RC beams under free loading after crack and sustained loading. The comparative study was executed to evaluate effects of pre-loading conditions on the structural behavior of the cracked RC beams after crack-repair. The strains of reinforcement and concrete and deflections of beams at each loading step were measured and evaluated. As the results of this study, repair methods have much influence on structural behavior of epoxy injected RC beams and epoxy injection method for cracks of RC structures is appeared to be efficient.

• KIEAE Journal
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• v.15 no.6
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• pp.19-26
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• 2015

Purpose: The repair would require to conserve and improve the building function and performance since built. Each household is responsible for maintaining the public facilities and paying the required cost. Therefore, it needs to get the tool or method to forecast the required cost in the future. Before the repair cost is provided, it needs to catch the repair cost distribution and provide the unit cost for the repair cycle. In this study, it aimed at providing the repair cost unit and analyzing the repair cost distribution in a roof proofing work, elevator work and building painting, which are divided into a fully work and partly change. Results of this study are shown that first, the average repair cost for roof proofing work is provided with $166.59{\times}10^3won/household$ and $1.59{\times}10^3won/m^2$ of a full change, $33.22{\times}10^3won/household$ and $0.33{\times}10^3won/m^2$ for a partly work. In addition, elevator work is $557.45{\times}10^3won/household$ and $5.38{\times}10^3won/m^2$ for a full change, $32.92{\times}10^3won/household$ and $0.56{\times}10^3won/m^2$ for a partly repair. Painting has a $304.48{\times}10^3won/household$ and $2.94{\times}10^3won/m^2$. Second, the distribution pattern of repair unit cost has a weibull-typed distribution which has a long tail to the right.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.132-137
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• 2008

A failure analysis of ammonia converter which suffered hydrogen attack in two years since its initial operating time was presented. It is constructed from 2.25 Cr.1 Mo steel. Analysis showed that the failure on closing seam weld joint was due to local improper post weld heat treatment (PWHT). Improper PWHT can introduce high residual stresses in thick-walled pressure vessel. High residual stress level in weld joint is very prone to hydrogen attack for any components which are operating in hydrogen gas environment. The repair procedures based on the principle to decrease the residual stress then proposed. The repair was controlled very carefully by applying several nondestructive tests in the each stage of repair. To assure the successful of the proposed repair, after one year since repair time, high temperature ultrasonic and TOFD methods were applied on-stream to this equipment in order to evaluate its post repair condition. The two methods showed good results on the repaired area.

• Journal of the military operations research society of Korea
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• v.26 no.2
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• pp.39-54
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• 2000

This research is carried out solving problem of reduction in the rate of operation for the k-1 tank in order to increase the availability, caused by the delay in supply of k-1 tank repair parts in field operations. In other words, the study aims to find the most suitable requirement estimate pattern for the main repair parts that are used for k-1 tank. This study intends to present the most suitable requirement estimate pattern for k-1 trank repair pats by comparing the results of repair parts consumption data in relation to their pattern created by the programs of the requirement estimate technique(moving average method) currently used in the Army and adaptive exponential smoothing model. The results of this study numerically proved that the adaptive exponential smoothing model is the most appropriate technique in estimating the requirement for k-1 tank repair parts.

• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.33-43
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• 2016

Grinding, weld deposition, type A sleeve, type B sleeve, composite sleeve, hot tapping and clamp are used as the method to repair the buried pipelines in the United States, UK and Europe. In the event of defect to the pipeline, they have repaired the pipeline through the fitness-for-service assessments. In addition, they have guidelines for the possible repair methods to apply to each type of damage, which is occurred due to the 3rd party construction or corrosion. According to the KGS FS551, Safety Validation in Detail including ECDA(External Corrosion Direct Assessment) as one method of integrity management should be carried out for the old pipeline which supply natural gas as the middle pressure in Korea. Where a defect on the pipelines is found, on the result of Safety Validation in Detail, the pipelines should be repaired or replaced by new piping. However, there are no guidelines or regulations regarding the repair and reinforcement of pipeline, so that, cutting the damaged pipeline and replacing it as a segment of new pipe is the only way in Korea until now. We have suggested pipeline repair methods including type A, B sleeve, composite sleeve, after the survey of foreign repair method and standards including the method of United States and the United Kingdom, and after analysis of the results on pipeline repair test including type A, type B sleeve and composite sleeve.

• Computers and Concrete
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• v.9 no.2
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• pp.99-118
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• 2012

Marine Structures are very costly and need a continuous inspection and maintenance routine. The most effective way to control the structural health is the application of an expert system that can evaluate the importance of any distress on the structure and provide a maintenance program. An extensive literature review, interviews with expert supervisors and a national survey are used to build a decision support system for concrete structures in sea environment. Decision trees are the main rules in this system. The system input is inspection information and the system output is the main cause(s) of distress(es) and the best repair method(s). Economic condition, severity of distress, distress situation, and new technologies and the most repeated classical methods are considered to choose the best repair method. A case study demonstrates the application of the developed decision support system for a type of marine structure.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.38 no.6
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• pp.360-365
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• 2012

The simultaneous surgical correction of bilateral cleft lip and nasal deformity has become a more common surgical technique that has greatly changed conventional strategies for secondary nasal correction. Mulliken has been known as one of the earliest proponents for the synchronous repair of bilateral cleft lip and nasal deformity, and he emphasized the responsibility of the treating surgeon to evaluate nasolabial growth by comparing anthropometric measurements with age-matched normal patients. Good outcomes from this surgical method have been reported in clinical cases worldwide. Herein, we describe the management of two cases of bilateral cleft repair, following the principles and methods established by Mulliken. We also provide a relevant review of the literature.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.487-490
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• 2005

In this study, for the establishment of the performance evaluation methods and the quality control standards of durability recovery method, the data of indoor durability test and the data of the long term exposure test under the coast are accumulated and analyzed. As a result of the indoor test, durability of repair material was more superior to that of plain concrete, but as a result of investigating and evaluating exposure test at 30 month of exposure age under the coastal environment, the difference in electric potential and the reinforcement corrosion at place replaced with repair material are found.

• Korean Management Science Review
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• v.26 no.1
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• pp.209-223
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• 2009

In this paper, an analysis problem of repair levels and spare part allocation for MIME(Multi indenture multi echelon) systems is studied using simulation and meta-heuristics. We suggest a method to determine simultaneously repair levels and spare parts allocation to minimize the life cycle cost of MIME system under availability constraint. A simulated annealing method is used to analyze the repair levels and genetic algorithm is used to obtain the optimal allocation of spare parts. We also develop a simulation system to calculate the life cycle cost and system availability. Some numerical examples are also studied.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.267-270
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• 2005

Recently, the damaged concrete structures are often strengthened or repaired using the polymer concrete or the polymer cement mortar. In the repaired concrete structures at early ages, internal stresses could be developed due to the differential drying shrinkage of the repair material. Due to the difference of the thermal coefficients of the repair material and existing concrete, additional stresses also could be developed as the structures are subjected to the ambient temperature changes. Theses environmentally-induced stresses can sometimes be large enough to cause damage to the structures, such as debonding of the interface between the two materials. In this study, a rational procedure was developed where anchors can be designed and installed to prevent damages in such structures by thermally-induced stresses. Finally, through the experimental and numerical study, the effects of the repair method using anchors with debonding was investigated and discussed the results.