• 한국건설순환자원학회논문집
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• 제8권3호
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• pp.372-378
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• 2020

본 연구에서는 콘크리트 하수관로의 결함부를 보수하기 위한 자주차의 개발 및 성능평가에 관한 연구를 수행하였다. 비굴착 방식인 자주차를 활용한 하수관로 보수를 위하여 구동 시스템, 보수 유닛 설계 및 보수재료 압송에 관한 성능을 고려하여 자주차를 개발하였다. 개발된 자주차의 성능평가를 하기 위하여 직경 500mm 콘크리트 하수관로에 결함부를 모사하여 보수실험을 수행하였다. 이후, 보수가 완료된 하수관로를 양쪽 끝단과 결함부에 플러그를 삽입하여 고정하고, 물을 주입하여 보수부위에서 누수 여부를 통한 수밀성능을 평가하였다. 누수량은 0.07L/㎡으로 허용 누수량 0.2L/㎡ 이하의 값을 나타내며 우수한 수밀성능을 나타내었다. 따라서 본 연구에서 개발한 자주차는 우수한 보수성능을 나타내는 것으로 판단된다.

• 한국구조물진단유지관리공학회 논문집
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• 제3권3호
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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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• 제26권4호
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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.

• 한국구조물진단유지관리공학회 논문집
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• 제27권6호
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• pp.62-69
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• 2023

본 연구에서는 보수재료에 굵은 골재를 사용하게 되면서 얻을 수 있는 효과를 검토하기 위해 굵은 골재의 최대치수 및 조립률을 다양화 하면서 콘크리트의 특성을 파악하는 기초 연구를 수행하였다. 그 결과 콘크리트의 슬럼프는 굵은 골재 최대치수가 커질수록 증가하였고, 공기량은 최대 골재 치수가 10 mm 이상인 배합군에 비해 최대 골재 치수가 5 mm 의 골재를 사용한 배합에서 공기량이 1.88~2.35 배 높게 측정되었다. 압축강도는 굵은 골재의 실적률에 많은 영향을 받는 것으로 나타났다. 실적률이 가장 높은 최대치수 20 mm 의 굵은 골재를 사용한 배합에서 압축강도가 가장 높게 측정되었으며 실적률이 가장 낮은 배합의 압축강도보다 45% 이상 높게 나타났다. 건조수축 측정결과 굵은 골재 최대치수 및 조립률의 변화에 따라 굵은 골재의 실적률이 높아지면서 건조 수축이 가장 낮게 측정되었고, 실적률이 가장 낮은 배합에서 가장 크게 나타났다. 본 연구를 통해 콘크리트 구조물 보수용 재료에 사용되는 굵은 골재의 최대치수 및 조립률을 다양화해서 입도를 조정하게 되면 강도 및 작업성이 우수해지고 건조수축을 줄일 수 있는 것을 확인 할 수 있었다.

• 조명전기설비학회논문지
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• 제27권1호
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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.

• 한국구조물진단유지관리공학회 논문집
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• 제21권4호
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• pp.104-109
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• 2017

프리믹스 타입의 보수 모르타르는 제조 과정에서 여러 원료들을 동시에 혼합해야 하므로, 혼합 시 생산 제품의 효과를 극대화하기 위해서는 원료 혼합 분포를 일정하게 하는 것이 중요하며, 생산 제품의 효과의 편차를 최소화하기 위해서는 혼합 설비의 성능을 높일 필요가 있다. 따라서 본 연구에서는 실제 생산 현장에서 활용되는 대표적인 혼합설비 3종을 대상으로 보수 모르타르를 제조하고 각각의 제반물성을 검토하였다. 그 결과, 프리믹스 타입 보수 모르타르의 제반 물성은 혼합설비의 종류에 따라 차이가 있었으며, 무중력 믹서가 상대적으로 우수한 결과 값을 보였다. 또한 작업성 및 최적 물성을 확보하기 위해 혼합시간을 10분에서 15분 정도로 하는 것이 바람직함을 확인하였다.

• Journal of Computational Design and Engineering
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• 제2권2호
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• pp.119-127
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• 2015

In the case of a high-valuable asset, the Operation and Maintenance (O&M) phase requires heavy charges and more efforts than the installation (construction) phase, because it has long usage life and any accident of an asset during this period causes catastrophic damage to an industry. Recently, with the advent of emerging Information Communication Technologies (ICTs), we can get the visibility of asset status information during its usage period. It gives us new challenging issues for improving the efficiency of asset operations. One issue is to implement the Condition-Based Maintenance (CBM) approach that makes a diagnosis of the asset status based on wire or wireless monitored data, predicts the assets abnormality, and executes suitable maintenance actions such as repair and replacement before serious problems happen. In this study, we have addressed several aspects of CBM approach: definition, related international standards, procedure, and techniques with the introduction of some relevant case studies that we have carried out.

• 한국건축시공학회지
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• 제7권2호통권24호
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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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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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.