• 한국구조물진단유지관리공학회 논문집
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• 제27권5호
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• pp.97-104
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• 2023

본 연구는 RC 구조물의 균열보수를 위한 보수재로서 폴리머 디스퍼전과 시멘트만으로 구성된 폴리머 시멘트 복합체 (polymer cement Composites ; PCCs)를 제작하여 실험적으로 기초물성을 파악하고자 하였다. 연구를 위한 시험배합은 EVA 및 SAE 폴리머 디스퍼전을 기반으로 보수재의 충전성을 고려하여 폴리머 시멘트비를 4가지(20, 60, 80 및 100%)로 변환시키면서 물시멘트비를 정해 PCCs의 점도를 결정하였다. 또한 PCCs의 강성을 개선시키기 위하여 P/C 80%와 100%에 실리카퓸을 혼입한 시험편도 제작하였다. PCCs의 균열보수용으로서의 점도, 유동성, 충전성, 인장강도, 신장률 및 탄성계수 등 기초적 물성을 실험하였다. 연구결과, 폴리머의 종류에 따라 P/C는 점도와 유동성에 큰 영향을 미쳤으며 RC 구조물의 균열보수용으로서 충전성을 고려한 적절한 점도를 맞춘 배합설계를 위해 상당한 가수가 필요하였다. 본 연구에서 설계한 모든 배합은 충전성이 우수하였으며, PCCs의 인장강도와 신장률은 시멘트 혼입 폴리머계 방수재에 대한 KS 규정을 만족하였다. 또한 실리카퓸을 혼입함으로써 PCCs의 인장강도와 탄성계수가 개선되었으며, 폴리머 종류에 따라서는 SAE를 사용한 경우가 EVA를 사용한 경우에 비해 RC 구조물 균열 보수재로서 우수한 기초적인 물성을 나타냈다. 본 연구결과를 종합하면, RC 구조물의 균열보수용으로 SAE를 사용한 P/C 80% 또는 100%와 실리카퓸 30%까지 혼입한 배합을 적절한 배합으로 제안할 수 있었다.

• 산업경영시스템학회지
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• 제32권2호
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• pp.171-178
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• 2009

Logistic support activities for weapon systems play an important role at maintenance activities in modern warfares. These activities are essential for keeping weapon systems ready at all time. However, maintenance supplies can be delayed without a proper information system. Further, increases of mean time to repair (MTTR) and unavailability of weapon systems can be occurred. In this study, a web based information system is developed for logistic chains of class 9 supplies. Utilizing web database technologies, the developed system can provide an environment for data exchange and sharing among various participants in the supply chain.

• International Journal of Railway
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• 제1권4호
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• pp.134-142
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• 2008

Serving as a strategic crossing point for major corridors in Central Europe, Railnet Austria's Infrastructure Network incurs continual increases in international traffic flows and is therefore subject to accumulating traffic congestion with potential restrictions to infrastructure access. This imposes challenges towards preserving open access to Railnet Austria's existing railway network and hinders quality infrastructure service during maintenance, repair, and upgrading. Through Railnet Austria's experiences, the economic viability of a railway network can be sustained through maintaining open access with good quality service of planned trainpaths, thus representing new challenges for future infrastructure maintenance and capacity planning. Railnet Austria's Capacity Management Department has proven that these challenges can be accommodated more effectively through recent technological developments in data warehousing and software development.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2004년도 추계학술대회
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• pp.131-141
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• 2004

This study deals with the procedure of safety improvement, productivity increase, and tact-time reduction through setting up the system about preventive maintenance. Actually, it is hard to establish and carry out preventive maintenance, even though we recognize the importance of the system concerning time, cost, labor, and so forth. In this study in the viewpoint of cost we are for achieving maximum efficiency by change and reduction of planning process adapted to the special work group. At first we briefly will mention the kind, the necessity, and the concept of preventive maintenance, and then divide the equipment used in the assembly line into the two whether it is necessary or not by way of estimating the breakdown loss, comparing with general establishment of preventive maintenance and modifying it to the case. At the second step we will establish the operation system of plan management related to production and quality in the special case. Check period and category will be set by dividing the assembly equipment into LCL and Focus in the third step. The forth step will contain the operation procedure in detail. And then we must make check and repair record periodically. Finally, on the basis of the record the selection of checking of significance will be conducted. This results in safety improvement, tact time reduction, and productivity improvement.

• 대한안전경영과학회지
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• 제7권1호
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• pp.101-115
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• 2005

This study deals with the procedure of safety improvement, productivity increase ,and tact-time reduction through setting up the system about preventive maintenance. Actually, it is hard to establish and carry out preventive maintenance, even though we recognize the importance of the system concerning time, cost, labor, and so forth. In this study in the viewpoint of cost we are for achieving maximum efficiency by change and reduction of planning process adapted to the special work group. At first we briefly will mention the kind ,the necessity ,and the concept of preventive maintenance ,and then divide the equipment used in the assembly line into the two whether it is necessary or not by way of estimating the breakdown loss ,comparing with general establishment of preventive maintenance and modifying it to the case. At the second step we will establish the operation system of plan management related to production and quality in the special case. Check period and category will be set by dividing the assembly equipment into LCL and Focus in the third step. The forth step will contain the operation procedure in detail. And then we must make check and repair record periodically. Finally, on the basis of the record the selection of checking of significance will be conducted. This results in safety improvement, tact time reduction, and productivity improvement.

• 한국관개배수논문집
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• 제18권2호
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• pp.142-160
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• 2011

This study was performed to apply the preventive management technique that is known for more economic and preventive for disaster than corrective technique to Repair & Improvement(R&I) Project policy of irrigational facilities. The appropriate periods of R&I Project had been driven to 40yrs, 24yrs, 27yrs, and 29yrs for reservoir, Pumping and drainage pumping station, Diversion weir and Irrigation & drainage canal respectively. The cost of R&I Project for 10 years had been estimated as 616.9 billion won per year including the 85 billion won for the project of 'Disaster prevention and Function continuity'. After the period of 'Improvement all at once', about 30yrs, 421.8 billion won was requested for 'Function continuity'.

• Communications for Statistical Applications and Methods
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• 제12권1호
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• pp.1-9
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• 2005

Burn-in is an engineering method which is used to eliminate early failures of products or systems after they have been produced. Recently, various models for determining optimal burn-in times have been developed, where some preventive maintenance policies were considered together with burn-in problem. In this paper, a survey of recent research in burn-in is undertaken.

• 한국생산제조학회지
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• 제9권2호
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• pp.125-137
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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 moldel.

• 한국정밀공학회지
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• 제15권6호
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• pp.5-14
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• 1998

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.

• 한국압력기기공학회 논문집
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• 제16권2호
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• pp.10-17
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• 2020

Securing the integrity of steam generator tubes is an essential requirement for safe operation of nuclear power plants. Therefore, tubes that do not satisfy integrity requirements are no longer usable and must be repaired according to the related requirements. In general, the repair criterion is that the damage depth is more than 40% of the tube wall thickness. However, the plugging limit can be changed and be applied, provided a technical proof is given that integrity can be secured against specific degradation at a specific plants and that approval can be obtained from a regulatory agency. A typical example is alternative repair criteria for defects within the tube sheet or tube support plates. In this paper, a background of establishing the plugging limit for steam generator tubes and changes in maintenance criteria are reviewed as examples.