• 한국도로학회논문집
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• 제14권5호
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• pp.11-19
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• 2012

PURPOSES: The new methodology is proposed for estimation of long-term performance and pavement life based on the national highway database in Daejeon area. Furthermore, this study tried to verify the applicability of performance estimation using NHPCI (National Highway Pavement Condition Index) on tendency of pavement deterioration as time goes by under Korean road environments. METHODS: Reliability theories are applied to estimate the mean life and to determine the appropriate distribution using 3 levels of traffic loads (high, medium, low) based on maintenance and rehabilitation history data for 15 years. RESULTS: As a result, Lognormal distribution is suitable for explanation of pavement lifetime in Daejeon area regardless of traffic loads. In addition, we found that the results of mean life and maintenance timing based on NHPCI for the pavement sections of 3 levels of traffic loads are available. CONCLUSIONS: Based on this study, it was found that mean life of high, medium and low levels of traffic loads are about 8.1 years, 12.2 years and 12.7 years, respectively. Higher level of traffic loads shorten the pavement mean life.

• 풍력에너지저널
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• 제14권3호
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• pp.34-42
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• 2023

The reduction of operation and maintenance (O&M) costs is a critical factor in determining the competitiveness of wind energy. Predictive maintenance based on the estimation of remaining useful life (RUL) is a key technology to reduce logistic costs and increase the availability of wind turbines. Although a mechanical component usually has sudden changes during operation, most RUL estimation methods use the trend of a state index over the whole operation period. Therefore, overestimation of RUL causes confusion in O&M plans and reduces the effect of predictive maintenance. In this paper, two RUL estimation methods (load based and data driven) are proposed for the bearings of a wind turbine with the results of trend classification, which differentiates constant and increasing states of the state index. The proposed estimation method is applied to a bearing degradation test, which shows a conservative estimation of RUL.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1366-1372
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• 2011

Life cycle of the rolling stock is normally 20 to 40 years, though there is some difference in accordance with each vehicle. Maintenance cost is over the twice of purchasing price. and also it is true that precise statics is not managed properly except for some developed countries due to the difference of maintenance method, skills. After KORAIL introduced ERP system in 2007, maintenance cost is managed by type of cars, by unit. but, afterwards it should be controlled as an index and also more precisely. it is the best pending issues to make train maintenance efficiency, to utilize accumulated indexes. I want to attribute to train maintenance efficiency by analysing what is the problems in the present maintenance method.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1494-1500
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• 2008

Life cycle of the rolling stock is normally 20 to 40 years, though there is some difference in accordance with each vehicle. Maintenance cost is over the twice of purchasing price. and also it is true that precise statics is not managed properly except for some developed countries due to the difference of maintenance method, skills. After KORAIL introduced ERP system in 2007, maintenance cost is managed by type of cars, by unit. but, afterwards it should be controlled as an index and also more precisely. it is the best pending issues to make train maintenance efficiency, to utilize accumulated indexes. I want to attribute to train maintenance efficiency by analysing what is the problems in the present maintenance method.

• 한국구조물진단유지관리공학회지
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• 제17권1호
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• pp.4-9
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• 2013

• 한국구조물진단유지관리공학회 논문집
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• 제1권2호
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• pp.131-140
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• 1997

콘크리트 교량을 저렴하고 신속하게 상태 평가를 하기 위하여 성능 지수(Performance Index)를 제안한다. 이 기법은 육안 검사에 의하여 발견된 결함의 범위와 심각도를 사용하여 콘크리트 교량의 전반적인 상태를 신속하게 등급화 하고 콘크리트 교량의 노출 조건을 고려하여 콘크리트 성능을 정량적으로 평가한다. 또한 본 연구에서는 상기한 성능 지수 기법의 타당성을 증명할 수 있는 정밀 안전 진단 시험결과를 활용하여 6개의 주요 노후화 원인을 고려하는 또 다른 성능 지수를 제안한다. 이러한 두 상태 평가 방법이 영국의 실제 교량 상태 평가 자료를 바탕으로 한 상태 평가 결과를 퍼지 집합 이론(fuzzy set theory)으로 분석한 결과와 비교하여 방법의 정당성 및 신뢰성을 논의한다.

• 한국도로학회논문집
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• 제19권5호
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• pp.1-11
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• 2017

PURPOSES : This study is aimed at development of a stochastic pavement deterioration forecasting model using National Highway Pavement Condition Index (NHPCI) to support infrastructure asset management. Using this model, the deterioration process regarding life expectancy, deterioration speed change, and reliability were estimated. METHODS : Eight years of Long-Term Pavement Performance (LTPP) data fused with traffic loads (Equivalent Single Axle Loads; ESAL) and structural capacity (Structural Number of Pavement; SNP) were used for the deterioration modeling. As an ideal stochastic model for asset management, Bayesian Markov multi-state exponential hazard model was introduced. RESULTS:The interval of NHPCI was empirically distributed from 8 to 2, and the estimation functions of individual condition indices (crack, rutting, and IRI) in conjunction with the NHPCI index were suggested. The derived deterioration curve shows that life expectancies for the preventive maintenance level was 8.34 years. The general life expectancy was 12.77 years and located in the statistical interval of 11.10-15.58 years at a 95.5% reliability level. CONCLUSIONS : This study originates and contributes to suggesting a simple way to develop a pavement deterioration model using the total condition index that considers road user satisfaction. A definition for level of service system and the corresponding life expectancies are useful for building long-term maintenance plan, especially in Life Cycle Cost Analysis (LCCA) work.

• 한국철도학회논문집
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• 제10권2호
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• pp.167-178
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• 2007

In general, it is known that the concrete ballast track is possible to reduce a cost of maintenance activities cause of maintenance free by restrictive maintenance in application of track ballast structures. However, if deteriorations and fracture mechanism of a material are considered, proper maintenance activities and repairing are continually required. For the problems, we evaluated an economical efficiency of the gravel ballast and the concrete ballast on a proper level of maintenance activities. As the method based on history path is difficult to obtain sufficient reliabilities cause of an absence of real data for maintenance activities, we chose the delphi survey method by professional group, and we obtained the appropriate index and profiles for maintenance activities. As a result, we founded that effects for cost reduction can be expected by preventive maintenance management, and we proposed economical restrictions and life cycle cost for track ballast structures in a life cycle.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1126-1131
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• 2008

In this paper we introduce an applicable RCM(Reliability centered maintenance) method for Track circuit equipment of AREX's Signalling System. AREX computerize all the process of FRACAS(Failure Reporting, Analysis and Corrective Action System)) by the Facility Management System of Integrated Information System. These datum were analysed and reproduced as the RAMS index value which can be used by maintenance staff for optimizing the maintenance method of the System.

• 한국구조물진단유지관리공학회 논문집
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• 제8권3호
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• pp.251-261
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• 2004

최근에 교량구조물의 부식과 노회에 대한 관심이 모아지고 있는 상황에서 부식된 철근의 불확실성은 교량구조물의 안전성 뿐만 아니라 철근콘크리트 부재의 휨강도에 영향을 미치고 있다. 이 논문에서는 이들 불확실성을 고려한 신뢰성 뼈대구조물의 거동과 최적유지관리 시나리오에 대한 검증을 제시하고 있으며, 이들 과정은 부죄된 구조물의 생애주기를 고려한 프로그램에 의해 산출한 값이며 부식구조물의 신뢰성지수 프로파일에 의한 여러 형태의 구조물에 대한 영향을 고려하여 유지관리 효과에 대해 연구 하였다.