• Proceedings of the KSR Conference
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• 2010.06a
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• pp.261-267
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• 2010

Present maintenance of a high speed railway is after the fack maintenance that executes a task when measured value goes over threshold value except some planned maintenance. It is difficult from efficient management of maintenance human resource and equipment commitment because it is difficult to predict quantity of maintenance targets. Corrective maintenance is pushed back on the repair priority of other target to need repair and it is exceeded repair cost potentially. For safety and dependable track management because track deterioration prediction is linked directly with track's life and safety of train service, it is very important that track management be based on preventive maintenance. In this study, we propose statistics model of track quality to use track inspection data and forecast model for track deterioration prediction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.68-75
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• 2018

In this study, to solve the problems of the conventional crack repair and injection method, high elasticity latex was used as the material of the storage tube to withstand the high pressure in the center part differently from the general port. When the repair solution was injected into the crack part, The TPS method was developed so that the air existing in the TPS can be discharged. In addition, a new infusion port in which a valve blocking the backflow of the remediation solution was installed at the injection port was developed and the physical characteristics of the port were analyzed. As a result of the evaluation, it was found that the filling rate of the remedial solution was improved compared to the existing ordinary injector method, and the cracks were completely filled in the test conditions. Compressive strength and tensile strength after repair showed about 20% decrease after repair in case of using ordinary injector method, while TPS method showed about 2~7% increase after repair. The results of this study showed that the injection port method using the elastic storage tube increased the injection performance and the quality after repair compared to the conventional injector method. The result of this study is expected to be utilized as the basic data for application and commercialization of the result to the practical structure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.148-155
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• 2017

In this study, by using the international standards ISO TS 16774, Part 2 Test method for chemical resistance as a quality control method of injection type repair material used for leakage crack of underground concrete structure, the performance requirement against of chemical environment of underground concrete structures for repair materials was tested. For this testing 3 types for each of the 2 classes of repair materials(synthetic rubber, cement), with a total of 9 types repair materials, were selected and examined. As a result, the test results showed that the smallest performance deterioration by the change in the mass was with the synthetic rubber(RG) type as opposed to the cement type system, showing that the synthetic rubber type had the strongest relative resistance to chemical exposure. Furthermore, it is necessary to investigate the material with high resistance to chemical substances and to examine the material which can increase resistance to sodium hydroxide and sodium chloride in cement system. These results can be used as a basic index for the selection of repair materials with the strongest resistance to chemical environment found in concrete structures. In addition, it is expected that the test results derived in this study can be used as reference data that can be reflected in the quality improvement of the maintenance material to be developed later.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.171-177
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• 2010

As concrete structures are exposed to chemical substances, damaged from salt, or progressed to the neutralization, the surface damage of the structures is generated timely fashion, resulting shortened service life. Especially, the sulfate erosion causes rapid surface defects, and the steel skeleton becomes corroded due to the water infiltration, generating stability deterioration of the concrete structure. In this study, the physical characteristics of the acid-resistant mortar with aluminosilicates was investigated in order to resolve problems of the acid resistance, one of the most serious problems of the cement type repair material. As the result of the experiment, the test specimen turned to exhibit almost equivalent physical characteristics with those of concrete sectional repair materials in terms of compressive and bending strengths. As both the cement sectional repair material and the test specimen were immerged in sulfuric acid solution to examine weight changes, the test specimens exhibited only 4% loss of their weights while the cement sectional repair materials reached at the level of 80% or above, proving the excellence acid resistant characteristics of the test specimens. Consequently, the physical characteristics of acid resistant mortar with aluminosilicates were revealed to be superior than those of concrete sectional repair materials. It can be utilized as a sectional repair material where the acidic erosion is anticipated.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1235-1240
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• 2005

In this status no inspection standard of quality in repair of present concrete structure has a problem to repair for simple experience. In this paper for this problem improvement, it made an analysis of relation to injection quantity of crack width, injection time of crack width, injection pressure of crack width, injection pressure and time, injection quantity of structural size, injection quantity of structural individual crack position, injection time about crack width. and structural thickness. The data gained in analysis result be judged that it will help in systematic quality control about concrete structural repair.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.96-104
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• 2017

A one-shot system (device) refers to a system that is stored for a long period of time and is then disposed of after a single mission because it is accompanied by a chemical reaction or physical destruction when it operates, such as shells, munitions in a defense weapon system and automobile airbags. Because these systems are primarily related with safety and life, it is required to maintain a high level of storage reliability. Storage reliability is the probability that the system will operate at a particular point in time after storage. Since the stored one-shot system can be confirmed only through inspection, periodic inspection and maintenance should be performed to maintain a high level of storage reliability. Since the one-shot system is characterized by a large loss in the event of a failure, it is necessary to determine an appropriate inspection period to maintain the storage reliability above the reliability goal. In this study, we propose an optimal inspection policy that minimizes the total cost while exceeding the reliability goal that the storage reliability is set in advance for the one-shot system in which periodic inspections are performed. We assume that the failure time is the Weibull distribution. And the cost model is presented considering the existing storage reliability model by Martinez and Kim et al. The cost components to be included in the cost model are the cost of inspection $c_1$, the cost of loss per unit time between failure and detection $c_2$, the cost of minimum repair of the detected breakdown of units $c_3$, and the overhaul cost $c_4$ of $R_s{\leq}R_g$. And in this paper, we will determine the optimal inspection policy to find the inspection period and number of tests that minimize the expected cost per unit time from the finite lifetime to the overhaul. Compare them through numerical examples.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.107-111
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• 2008

This paper presented a literature review and investigation analysis results of total 19 present guide book and provisions of maintenance and management system in existing railway bridges to development of urban maglev track structures inspection manual. This research carried out a cooperated research subject 3-1, development a design code and maintenance and management inspection manual for urban maglev track structures, of the Center for Urban Maglev Program. Three types of track structures were includes as a major analytical parameter together with railroad, high speed railroad, subway and light rail transit. Bridges were analyzed a general rules, investigation, evaluation, repair and strengthen method as a key aspect. And rail were analyzed examination and maintenance also. This analysis results show that the track structures evaluation are based on the test and examination results, and repaired or strengthened consideration of deterioration, track irregularity and materials according to provision requirements.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.243-248
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• 2008

Seoul subway is an safety, quick, and clean public transportation to secure citizens safety. One of the most important elements of train is optimizing railroad function and need to conform railroad inspection for function maintenance. Railroad is the most biggest part of the railroad facility and it is a structure which requires sustainable maintenance. The purpose of study is to improve domestic metropolitan railroad facility inspection method and period. For this, we refer documents about present roving method, roving members and period of railroad roving. In addition, analyzed problems of railroad roving investigation method and period by examining the type and standards of railroad investigation and interviewing experts. By this, we analyzed improving plan and expectations of railroad maintenance and repair operation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.1
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• pp.279-288
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• 2003

This study is the development of method on repairing concrete structure for progressing the durability of reinforced concrete. This method is wet spray method which compress and conduct mortar pre-mixed with polymer powder to hose by high pressure pump and spray it on the section of concrete structure through nozzle made specially. Characters of this method are that materials are selected with the sort of structure and the cause of deterioration and macro pores are removed in repaired section by conducting with high pressure and spraying with high velocity for progressing the durability of concrete structure. This study has carried out that the minimum capacity of rebound was measured with various condition and physical properties of sample made by spray method were estimated in comparing with sample made by previous hand method. Also, properties of long-term have carried out after this method was applied on site. According to experimental study, the capacity of rebound showed below 5% and physical properties of sample made by spray method were superior to that of sample made by hand method and physical and durable properties of long-term showed excellence.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.234-239
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• 2004

Recently, the tunnel structures are increasing. And the tunnels are to be large diameter tunnel and long. Therefore, inspection, repair, and maintenance of tunnels are an extremely important part of infrastructure management, with particular technical and safety considerations arising from the very nature of underground construction. To inspect surface state of tunnels, concrete structures, it must generally use method of conventional visual inspection, but this method is very not objective. To measure the width, length, position, direction of a crack, it is very difficult, when the tunnel is long span and high rise. Thus, to make up for this demerits, in this paper is proposed the Tunnel Scanning System that we can check conditions of the tunnel structures quickly, detect the detailed data objectively, count automatically the width of a crack by the original software and follow the trend of long tenn changes in the condition of a tunnel.