• Structural Monitoring and Maintenance
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• 제1권4호
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• pp.357-369
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• 2014

In the existing bridge management systems, assessment of the structural behavior is based on the results of visual inspections in which corresponding condition states are assigned to individual elements. In this process, limited attention is given to the correlation between bridge elements from structural perspective. Also, the uncertainty of parameters which affect the structural capacity is ignored. A system reliability-based assessment model is potentially an appropriate replacement for the existing procedures. The aim of this research is to evaluate the system reliability of existing conventional Steel-Reinforced bridge decks over time. The developed method utilizes the reliability theory and evaluates the structural safety for such bridges based on their failure mechanisms. System reliability analysis has been applied to simply-supported concrete bridge superstructures designed according to the Canadian Highway Bridge Design Code (CHBDC-S6) and the deterioration pattern is achieved based on the reliability estimates. Finally, the bridge condition index of an old existing bridge in Montreal has been estimated using the developed deterioration pattern. The results obtained from the developed reliability-based deterioration model and from the evaluation done by bridge engineers have been found to be in accordance.

• 한국수자원학회논문집
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• 제51권11호
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• pp.959-969
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• 2018

노후화된 상수관로는 단수유발, 수압부족 및 수질악화, 싱크홀 발생 피해와 누수로 인한 경제적 손실 등을 초래한다. 하지만 모든 노후관로를 일시에 보수 및 교체하는 것은 불가능하므로, 사용 중인 관로의 노후도를 정량적으로 판단하여 상수관로의 개량 우선순위를 결정해야 한다. 본 연구에서는 ANN(Artificial Neural Network)-Clustering 기법이 상수관로의 노후도 평가를 위한 새로운 평가방법이 될 수 있음을 제시하였다. 본 연구는 전라남도 YG지역의 배수관로를 적용대상으로 진행하였으며, 관망성능평가 항목을 이용하여 전체 관로를 세 개의 등급으로 분류하여 노후도를 평가하였다. 또한, 본 연구의 적용 가능성을 판단하기 위하여 실무에서 적용 중인 점수평가법 결과와 비교분석을 실시하였으며, 전체 대상관로의 노후도 정도를 직관적으로 파악할 수 있도록 산정된 노후도 등급을 관망도에 도시하였다. 본 연구에서 제안한 노후관로 평가기법은 관로의 다양한 특성값을 손쉽게 변경하여 적용할 수 있으며, 점수평가법과 더불어 상수관로의 유지관리를 위한 객관적이고 합리적인 관망성능평가법이 될 수 있을 것으로 기대한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1990년도 가을 학술발표회 논문집
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• pp.45-50
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• 1990

This study develops practical models and methods for the assessment of safety and capacity rating of existing P.C. girder bridges based on the reliability methods. One of the main objectives of the study is to propose a practical but realistic limit state model for safety assessment and LRFR rating criteria, which explicitly incorporates the degree of deterioration and damage as well as actual condition of P.C. girder bridges in terms of the damage factor and the response ratio. The damage factor proposed in the paper is defined as the ratio of the current estimated stiffness to the intact base-line stiffness of a member. Based on the observation and the results of applications to existing bridges, it may be concluded that the proposed methods for the assessment and capacity rating models, which explicitly account for the uncertainties and effects of degree of deterioration or damage, provide more realistic and consistent safety-assessment and capacity rating.

• Journal of the Korean Wood Science and Technology
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• 제31권2호
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• pp.58-68
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• 2003

목조 고건축물의 안전성 평가를 위해서는 먼저 부재의 성능평가가 선행되어야 한다. 지금까지의 목재 부재의 성능평가는 육안에 의한 경험적 방법에 의존하였다. 하지만 과학적이고 합리적인 비파괴 방법을 적용하여 구조부재의 성능을 평가할 수 있다면 구조물의 안전성 해석은 더욱 정확해지고 합리적이 될 것이다. 이를 위해 본 연구에서는 목조 고건축물의 여러 구조 부재 중 기둥에 대해 비파괴 평가법을 적용하여 구조부재의 성능 평가에 대한 가능성을 알아보았다. 이 결과를 이어지는 연구에서 구조물의 안전성 해석의 기초자료로 사용할 예정이다. 특별히 기둥의 노출 환경에 따른 열화의 진행정도를 비파괴 평가법으로 측정하였다. 그 결과 실제 육안에 의한 열화의 관찰과 유사한 결과를 나타내어 비파괴 방법의 적용 가능성을 보여주었다.

• Computers and Concrete
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• 제20권5호
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• pp.511-519
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• 2017

The reliability of reinforced concrete structures is frequently compromised by the deterioration caused by reinforcement corrosion. Evaluating the effect caused by reinforcement corrosion on structural behaviour of corrosion damaged concrete structures is essential for effective and reliable infrastructure management. In lifecycle management of corrosion affected reinforced concrete structures, it is difficult to correctly assess the lifecycle performance due to the uncertainties associated with structural resistance deterioration. This paper presents a stochastic deterioration modelling approach to evaluate the performance deterioration of corroded concrete structures during their service life. The flexural strength deterioration is analytically predicted on the basis of bond strength evolution caused by reinforcement corrosion, which is examined by the experimental and field data available. An assessment criterion is defined to evaluate the flexural strength deterioration for the time-dependent reliability analysis. The results from the worked examples show that the proposed approach is capable of evaluating the structural reliability of corrosion damaged concrete structures.

• Structural Engineering and Mechanics
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• 제85권4호
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• pp.531-543
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• 2023

The existing concrete bridges are time-varying working systems, where the maintenance strategy should be planned according to the time-varying performance of the bridge. This work proposes a time-dependent residual capacity assessment procedure, which considers the non-stationary bridge load effects under growing traffic and non-stationary structural deterioration owing to material degradations. Lifetime bridge load effects under traffic growth are predicated by the non-stationary peaks-over-threshold (POT) method using time-dependent generalized Pareto distribution (GPD) models. The non-stationary structural resistance owing to material degradation is modeled by incorporating the Gamma deterioration process and field inspection data. A three-span continuous box-girder bridge is illustrated as an example to demonstrate the application of the proposed procedure, and the time-varying reliability indexes of the bridge girder are calculated. The accuracy of the proposed non-stationary POT method is verified through numerical examples, where the shape parameter of the time-varying GPD model is constant but the threshold and scale parameters are polynomial functions increasing with time. The case study illustrates that the residual flexural capacities show a degradation trend from a slow decrease to an accelerated decrease under traffic growth and material degradation. The reliability index for the mid-span cross-section reduces from 4.91 to 4.55 after being in service for 100 years, and the value is from 4.96 to 4.75 for the mid-support cross-section. The studied bridge shows no safety risk under traffic growth and structural deterioration owing to its high design safety reserve. However, applying the proposed numerical approach to analyze the degradation of residual bearing capacity for bridge structures with low safety reserves is of great significance for management and maintenance.

• 환경영향평가
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• 제22권4호
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• pp.303-317
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• 2013

The purpose of this study is to offer the raw data for restoration and management of trails by assessing the physical environments, the types of deterioration and the naturalness on trails located in the Sogeumgang, Hwarang and Seoak districts of Gyeongju National Park, Korea. The Sogeumgang was 5.9m, 1.1m of the Hwarang and 1.8m of the Seoak district in trail width. In the bared width of trail, the Sogeumgang was 3.9m, 0.9m of the Hwarang and 1.7m of the Seoak district. In the depth of erosion, the Sogeumgang was 37.1cm, 14.2cm of the Hwarang and Seoak district. The Sogeumgang was $16.8^{\circ}$, $13.1^{\circ}$ of the Hwarang and $12.2^{\circ}$ of the Seoak district in longitudinal slope. In the left and right of transect slope, the Sogeumgang was $18.3^{\circ}$ and $12.6^{\circ}$, $18.0^{\circ}$ and $21.3^{\circ}$ of the Hwarang and $15.3^{\circ}$ and $22.7^{\circ}$ of the Seoak district. In the left, middle and right of soil hardness, the Sogeumgang was 29.9mm, 34.7mm and 31.1mm, 27.6mm, 35.0mm and 27.2mm of the Hwarang and 27.1mm, 30.8mm and 28.0mm of the Seoak district. The types of deterioration in trails were 10 types of the Sogeumgang, 11 types of the Hwarang and 9 types of the Seoak district. The trail erosion, rock exposure and root exposure were substantially observed in the types of deterioration. In the results of the naturalness assessment, the Hwarang district was a good condition, but the Sogeumgang district was bad. The indicators of the Sogeumgang district were mostly poor.

• 전기학회논문지
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• 제63권2호
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• pp.297-305
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• 2014

Nowadays new water supply projects have been on the decline as the water-power constructions have saturated, which means that the existing power equipment have slowly aged and they require more efforts to maintain the system performance. An effective asset management method of power equipment has become a great necessity from both economical and technical aspects. To be balanced, the asset management should look into all three parts: management, engineering, and information. The purpose of this paper is to study a Risk-Based Maintenance (RBM) matrix method through the deterioration evaluation algorithm for an efficient reliability assessment of oil-immersed power transformers by considering both asset management and technical evaluation. Make use of this result, the equipment will be decided to be replace or repair otherwise on service.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1990년도 봄 학술발표회 논문집
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• pp.37-43
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• 1990

This paper develops practical models and methods for the assessment of safety and rating of damaged and/or deteriorated bridges by incorporating a system identification technique for the explicit inclusion of the degree of deterioration or damage and of the actual bridge response. And, based on the proposed model, reliability-based rating methods are proposed as LRFR(Load and Resistance Factor Rating) and system reliability-index rating criteria. The proposed limit state model explicitly accounts for the degree of deterioration or damage in terms of the damage and response factors. The damage factor in the paper is proposed as the ratio of the current stiffness to the intact stiffness. Based on the observation and the results of applications to existing bridges, it may be concluded that the proposed rating models, which explicitly account for the uncertainties and the effects of degree of deterioration or damage based on the system identification technique, provide more realistic and consistent safety-assessment and capacity-rating.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 추계학술발표회
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• pp.640-641
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• 2005