• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.426-430
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• 2008

Though the air-conditioners in each train model have almost identical function, there is incompatibility between them because of their different electric capacity and parts, even spares manufactures are different in the manufactured year. It cause over cost in the maintenance and repair of the each air-conditioner. In this paper, all the air-conditioners in each train model have been classified by their capacity and features so that grasp the operation status and the repair process of the air-conditioners, and draft systematically cost-effective solutions. By finding a way to deal with the emergency repair and extending the air-conditioner life though improvement of checking up progress, increase of passenger revenue can be reached considerably.

• 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.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.3
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• pp.203-211
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• 1999

This study is to examine the feasibility of carbon fiber sheet(CFS), a kind of fiber reinforced plastic(FRP), for a repair and reinforcement of R/C beams. The flexural strength of R/C beams, that were preloaded and then the cracks were repaired, maintains that of the uncracked R/C beams. The flexural strength of R/C beams increases with the reinforcement of CFS. In order to practically apply the repair and reinforcement method, further research is needed for the distribution, amount, and bond of CFS. In this study, an experiment was conducted for R/C beams reinforced with CFS, for various wrapping method and amounts of CFS. Experimental results showed the wrapping method increasing the bond area and amount of CFS layer caused the increase in the strength of the beams. It is found that the strength of CFS should be used as 70% of the maximum strength in retrofitting reinforced concrete beams in evaluating flexural capacity on the basis of ultimate strength design method.

• Journal of Biosystems Engineering
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• v.26 no.4
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• pp.323-330
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• 2001

The regular maintenance and repair status of major farm machinery such as power tiller, farm tractor, rice transplanter and combine harvester etc., were surveyed and analyzed for the full-time farmers in order to get basic information for promoting farm machinery productivity. The survey was carried out through 209 farmers from 9 provinces. The results of this study can be summarized as follows; 1. The regular maintenance of farm machinery was conducted at repair shop(49.5%) or dealer agency(12.0%), and also conducted by farmers at their house(34.9%). 2. For the status on the cleanness or exchange times of engine oil, fuel filter and air cleaner, most farmers conducted fewer times than the necessary times. And, 5.3%, 7.7%, and 2.9% of surveyed farmers experienced breakdowns due to the insufficient cleanness or exchange oil, fuel filer, and air cleaner, respectively. 3. Most farmers(76.1%) recognized the necessity of farm machinery training or education, and they preferred one week for the training period, simple or easy maintenance for the training level, agricultural technical center or farm machinery manufacturer for the training agency. 4. Complete recognition of operation manual and sufficient maintenance before-, during-, and after-operation for the farm machinery can minimize the breakdowns, enlarge the endurance prevent the safety accidents, and promote productivity of farm machinery. And, these can be accomplished by the thorough training or education for agricultural machinery.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.62-69
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• 2023

Re-damage is frequently occurring for various reasons, including material factors, external factors, and factors caused by poor construction in concrete cross-section restoration work, so it is necessary to identify the cause and improve it. Cement-based materials are the most commonly used maintenance materials for concrete structures, and in particular, additional cross-sectional restoration work may be carried out due to re-damage such as cracks and excitement due to dry contraction of the repair material. In this study, a basic study was conducted to identify the characteristics of concrete while diversifying the maximum dimensions and assembly rate of thick aggregates to examine the effects of using thick aggregates in repair materials. As a result, the slump of concrete increased as the maximum size of thick aggregates increased, and the amount of air content was measured 1.88 to 2.35 times higher in the mixing using aggregates with a maximum aggregate size of 5 mm or more compared to the mixing group with a maximum aggregate size of 10 mm or more. It was found that compressive strength was greatly affected by the performance rate of thick aggregates. The compressive strength was measured the highest in the mixture using thick aggregates with the highest performance rate of 20 mm, and the compressive strength of the mixture with the lowest performance rate was more than 45%. As a result of the dry shrinkage measurement, the dry shrinkage was the lowest as the performance rate of the thick aggregate increased according to the change in the maximum dimensions and assembly rate of the thick aggregate, and the lowest performance rate was the largest in the mix. Through this study, it was confirmed that adjusting the particle size by diversifying the maximum dimensions and assembly rate of thick aggregates used in concrete structure repair materials can improve strength and workability and reduce dry shrinkage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.104-109
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• 2017

It is important to keep the distribution of the raw material mixture constant, in order to maximize the effect of the pre-mix type repair mortar, and it is also necessary to increase the performance of the mixer in order to minimize the deviation of the product. In this study, three kinds of mixer used in production sites were used to make repair mortar and the properties of each mortar were examined. As a result, it is confirmed to the difference in properties of pre-mix type repair mortar differ depending on the type of mixer, and the fluidized zone mixer showed relatively good results. In addition, it is preferable to set the mixing time to about 10 minutes to 15 minutes in order to ensure workability and optimum physical properties.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.1
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• pp.61-67
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• 2013

The turnout point system is installed to separate the main rail track from other tracks in rail load stations. It is also important to set up the switch point system to change the direction of the turnout point, to lead and change the direction of tracks. The switch point system can be negatively affected by heavy snow during winter seasons which can cause critical safety problems. Furthermore, the maintenance and repair of the conventional system is prohibitively expensive due to its complexity and high probability of failure. In this paper, an efficient switch point system is proposed which simplifies the equipment structure and lowers the cost for maintenance and repair, while improving safety and performance of the rail road system.

• Journal of the Korea Institute of Building Construction
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• v.7 no.2 s.24
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• pp.67-76
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• 2007

The purpose of this study is to propose the efficient improvement in the lawsuit to request the guarantee against defect. This study points out several problems about related act and subordinate statue and judgement by analyzing the character of contract in apartment house, related laws and regulations, appraisals and judicial decisions. This study deduces the necessity of the establishment of the specification and the breakdown cost for repair and maintenance work to provide the standard for the detached judgement.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.277-278
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• 2009

The building that supply tidal and splash zone was constructed near Seamangeum Gate Bridge. The specimens that will be tested for maintenance of gate bridge were exposed on the tidal and splash zone, totally about 650(Fig. 1). The characteristics of strength, salt penetration profile, field application of surface repair material and section recover material will be acquired by periodical test. The program was developed to obtain optimal maintenance strategy of gate bridge as a marine concrete structure and to deposit experimental data, lab. test result, field test result, on its D/B. On this paper, we hope to introduce two years exposure data as compressive strength, the modulus of elasticity, the modulus of dynamic elasticity, field adoption of repair and recover materials. As briefly speaking the results, possion's ratio, elasticity, strength was general, but the recover materials have some problems. There was crack between concrete and recover material and delamination figures.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.542-547
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• 2000

In this paper, we propose a new approach to the development of the automatic vision system to examine and repair the steam generator tubes at remote distance. In nuclear power plants, workers are reluctant of works in steam generator because of the high radiation environment and limited working space. It is strongly recommended that the examination and maintenance works be done by an automatic system for the protection of the operator from the radiation exposure. Digital signal processors are used in implementing real time recognition and examination of steam generator tubes in the proposed vision system. Performance of proposed digital vision system is illustrated by simulation and experiment for similar steam generator model.