• Journal of Korean Society of Water and Wastewater
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• v.23 no.3
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• pp.265-270
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• 2009

A nationwide questionnaire survey was conducted to investigate the actual conditions of local authorities in operating and maintaining sewerage systems especially for urban flooding. The questionnaire includes the incidences of flooding since 1980, the existence of any guidance for preventing flood damage and the design frequency currently used for sewers in each local authority. Among 160 local authorities responded to the survey, 95(59.3%) has experienced flooding more than once since 1980 while only 36(37.9%) of the 95 has prepared operation/maintenance guidelines for flooding. Most of the respondents have applied the 10 year design frequency for sewer design and 57(35.6%) of them agreed to adjust the 10 year design frequency regulation.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1174-1179
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• 2004

In general, the national rail system put an emphasis on distribution planing of stations for smooth operation of transporting goods, train allocation, parking, and maintenance. Since the national rail system is operated on the ground level, it is feasible to improve various aspects of the system during its operation. On the contrary, urban rail system is operated in the limited space under the ground, and thus, improving various aspects of the system during its operation is infeasible. Specifically, the urban subway system must have a comprehensive track distribution plan because the urban subway system has to operate in a limited environment such as it operates in a much shorter time period, The subway system has to be ready for various operations and events such as trains returning in the opposite direction. parking trains that need repair, parking during night time, storing various maintenance equipments, and connections to other tracks. Furthermore, considering the future extension of tracks, a comprehensive track distribution plan is a must.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.935-940
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• 2006

Present periodic maintenance activities are carried on electric rolling stock in Korea based on predetermined inspection intervals. And this can be seen as a first generation of maintenance techniques without taking into consideration a degree of aging or degradation of the componets. In this study, we have analyzed the current status of maintenance being used in the techniques in various activities such as overseas railway operation organization, and good cases for the advanced country's maintenance system being carried out effectively. Based on the analysis, we would derive implications for efficient application and improvement guidance of maintenance system in electric rolling stock.

• Journal of Energy Engineering
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• v.20 no.2
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• pp.154-162
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• 2011

PMT(Preventive Maintenance Template) is a standardized maintenance program that describes maintenance items & period as operation condition to increase component reliability at the component level. The existing maintenance programs are focused on time based maintenance to inspect and repair component depend on fixed period. But recently, we have developed advanced maintenance program(named PMT) to increase reliability and optimize maintenance program of the plant significant component. This paper presents how to develop the PMT for nuclear power plant's static exciter.

• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.147-151
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• 2002

Burn-in is a widely used method to eliminate initial failures. Preventive maintenance policy such as block replacement with minimal repair at failure is often used in field operation. In this paper burn-in and maintenance policy are taken into consideration at the same time. The cost of a minimal repair is assumed to be a non-decreasing function of its age. The problems of determining optimal burn-in times and optimal maintenance policy are considered.

• 연구논문집
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• s.27
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• pp.119-126
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• 1997

In this paper, an information management system is developed to systematically maintain facilities which include AS/RS(Automatic Storage & Retrieval System). Stacker Crane, Tool Transport system and Machining Center in FMS pilot plant. It supports various activities such as periodical inspection, maintenance, management of daily operation time, analysis of existing condition and management of information related to facilities.

• Journal of Advanced Navigation Technology
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• v.20 no.6
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• pp.511-518
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• 2016

RAPCON non only controls landing/take-off procedures but also approaching air traffics within 60-70 NM range of air force base. This paper, first of all, tries to research the failure rate per operation hours, mean time between failure (MTBF) of RAPCON according to six blocks such as interrogator, receiver, power unit, display unit, data process unit and antenna. In addition, this paper estimates the maintenance cost over next 10 months based on 50 monthly maintenance cost data. Considering the maintenance cost data from RAPCON which has been used over designed service life span, it is no doubt the forecasted data proved the monthly cost would go up incrementally during the rest of economic life of the facility. Such research result is also proven to be the same with the result of bathtub curve data during operating life.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1487-1493
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• 2008

Railway vehicle is very important to implement the effective maintenance in proper to prevent any failure during operation period. Many railway authorities are making efforts to maintain the railway vehicle through scientific and systematic procedure. To achieve this, Reliability Centered Maintenance(RCM) is partially applied. The efficiency of RCM has proven and its terminology was familiar with nuclear power, military and chemical plant etc. since the commercial aircraft's industries has introduced the maintenance program based on the target of reliability. The application of RCM on railway vehicle can be utilized with systematic analysis method to select the best effective maintenance period and action to prevent the failures by selecting the equipment affecting the its safety and reliability. This paper is presented that the procedure of adequate and effective maintenance for railway vehicle by comparing among the related standards in example IEC60300-3,11, MIL-STD-2173, and technical documents or papers. In accordance with above result, RCM procedure is proposed to apply effectively for maintenance of railway vehicle. That is, (1) Analysis of data and Calculation of criticality per equipment (2) Selection of equipment to analyze (3) Analysis of failure mode and effect (4) Evaluation of maintenance method and period (5) Optimization of maintenance program through renewal of maintenance method and period.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.2
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• pp.7-13
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• 2011

Turbine journal bearings are designed to support the weight of the rotors on a hydrodynamic oil film and to provide dynamic stability to the rotor system. The life time of journal bearings is infinite theoretically because the journal bearings are separated from the shaft journal by oil film. But poor design, assembly, operation and maintenance can cause problems to the journal bearings. The FMEA(Failure Mode and Effects Analysis) results of the journal bearings show that frequent maintenance of the journal bearings can cause failures and reduction of the bearing life. Therefore, the maintenance periods and history of the journal bearings with the bearing FMEA results are reviewed in order to establish the optimized maintenance period of the journal bearing for the nuclear power plants. Consequently it is necessary to maintain a best condition of lubrication system, reject time-based maintenance and perform the condition-based maintenance of journal bearings in order to maintain optimum condition of the journal bearing.

• KIEE International Transactions on Power Engineering
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• v.5A no.4
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• pp.331-338
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• 2005

In this paper, an improved maintenance scheduling approach suitable for the competitive environment is proposed by taking account of profits and costs of generation companies and the formulated combinatorial optimization problem is solved by using Reactive Tabu search (RTS). In competitive power markets, electricity prices are determined by the balance between demand and supply through electric power exchanges or by bilateral contracts. Therefore, in decision makings, it is essential for system operation planners and market participants to take the volatility of electricity price into consideration. In the proposed maintenance scheduling approach, firstly, electricity prices over the targeted period are forecasted based on Artificial Neural Network (ANN) and also a newly proposed aggregated bidding curve. Secondary, the maintenance scheduling is formulated as a combinatorial optimization problem with a novel objective function by which the most profitable maintenance schedule would be attained. As an objective function, Opportunity Loss by Maintenance (OLM) is adopted to maximize the profit of generation companies (GENCOS). Thirdly, the combinatorial optimization maintenance scheduling problem is solved by using Reactive Tabu Search in the light of the objective functions and forecasted electricity prices. Finally, the proposed maintenance scheduling is applied to a practical test power system to verify the advantages and practicability of the proposed method.