• Title/Summary/Keyword: 부식모델

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A Study on the Assessment of Chloride Penetration Due to Diffusion in NPP Concrete Structures (원전콘크리트 구조물의 확산에 의한 염소이온 침투평가에 관한 연구)

  • Kim, Do-Gyeum;Lee, Jang-Hwa;Kim, Ki-Beom;Lee, Ho-Jae
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2011.04a
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    • pp.404-405
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    • 2011
  • 원전구조물의 방사성 폐기물 처분시설의 경우 지하수에 해수가 유입되어 콘크리트에 염소이온 침투가 발생할 수 있으며, 콘크리트 내부에 존재하는 인장철근의 부식에 의한 내구성 저하 및 수명 단축이 주된 문제가 된다. 본 논문에서는 원전콘크리트 구조물에서의 확산에 의한 염소이온 침투에 대한 수학적 모델을 제시하였다. 콘크리트 중의 염소이온의 침투는 콘크리트의 노출환경, 습윤상태에 따라 확산(Diffusion), 대류(Absorption), 전기적 이동(Migration)에 의해 발생한다. 이러한 조건을 모두 고려하여 제시한 방정식에 의해 염소이온의 침투를 예측할 수 있다.

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Dual-mode diagnosis system for water quality and corrosion in pipe using convolutional neural networks (CNN) and ultrasound (합성곱 신경망과 초음파 기반 상수도관 수질 및 부식 분석용 이중모드 진단 시스템)

  • So Yeon Moon;Hyeon-Ju Jeon;Yeongho Sung;Min-Seo Kim;Daehun Kim;Jaeyeop Choi;Junghwan Oh;O-Joun Lee;Hae Gyun Lim
    • Proceedings of the Korea Information Processing Society Conference
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    • 2023.11a
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    • pp.685-686
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    • 2023
  • 상수도관의 수질 및 부식도 검사에는 파이프에 손상을 입히지 않고 지속적인 방법이 필요하다. 초음파는 이를 만족하면서 상태를 확인할 수 있고 주파수가 높을수록 해상도가 좋아져 정밀한 측정이 가능하다는 장점이 있다. 이러한 특성을 이용해 상수도관 모니터링 시스템으로 초음파 기반의 Scanning Acoustic Microscopy(SAM)과 Convolutional Neural Network(CNN)을 사용하는 새로운 방법을 제안한다. 기존의 Non-Destructive Testing(NDT)방식의 단점을 보완하면서 더 높은 해상도로 상수도관을 점검하는 방식으로, SAM 을 이용하여 부식으로 인한 파이프 두께 변화와 부유물의 여부 및 수질을 동시에 감지하고 얻은 데이터를 CNN 으로 분석했다. CNN 의 높은 정확도 결과로 이 시스템의 파이프 부식도 및 수질 모니터링에 대한 적합성을 보여주었다.

Durability Prediction for Concrete Structures Exposed to Chloride Attack Using a Bayesian Approach (베이지안 기법을 이용한 염해 콘크리트구조물의 내구성 예측)

  • Jung, Hyun-Jun;Zi, Goang-Seup;Kong, Jung-Sik;Kang, Jin-Gu
    • Journal of the Korea Concrete Institute
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    • v.20 no.1
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    • pp.77-88
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    • 2008
  • This paper provides a new approach for predicting the corrosion resistivity of reinforced concrete structures exposed to chloride attack. In this method, the prediction can be updated successively by a Bayesian theory when additional data are available. The stochastic properties of model parameters are explicitly taken into account into the model. To simplify the procedure of the model, the probability of the durability limit is determined from the samples obtained from the Latin hypercube sampling technique. The new method may be very useful in designing important concrete structures and help to predict the remaining service life of existing concrete structures which have been monitored.

Modeling of Chloride Ingress in Reinforced Concrete Structures (철근 콘크리트 구조물의 염소이온 침투 모델)

  • Koo, Hyun-Bon;Kim, Eui-Tae;Lee, Kwang-Myong
    • Journal of the Korea Concrete Institute
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    • v.15 no.1
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    • pp.25-34
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    • 2003
  • The degradation of reinforced concrete (RC) structures due to physical and chemical attacks has been a major issue in construction engineering. Deterioration of RC structures by chloride attack followed by reinforcement corrosion is one of the serious problems. An objective of this study is to develop a form of mathematical model of chloride ingress into concrete. In order to overcome some limits of the previous approaches, a chloride ingress model, consisting of chloride solution intrusion through the capillary pore and chloride ion diffusion through the pore water, was proposed. Moreover, the variability of chloride ion diffusivity due to the degree of hydration of cement, relative humidity in pore, exposure condition, and variation of chloride binding, was considered in the model. In order to verify the proposed model, the results predicted by the proposed model were compared with analysis results of Life-365, a computer program for predicting the service life of reinforced concrete structures exposed to chlorides. In conclusion, the proposed model would be promising to predict the chloride ion profile and to estimate the service life of RC structures.

A Prediction Method of the Gas Pipeline Failure Using In-line Inspection and Corrosion Defect Clustering (In-line Inspection과 부식결함 클러스터링을 이용한 가스배관의 고장예측)

  • Kim, Seong-Jun;Choe, Byung Hak;Kim, Woosik
    • Journal of the Korean Institute of Intelligent Systems
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    • v.24 no.6
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    • pp.651-656
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    • 2014
  • Corrosion has a significant influence upon the reliability assessment and the maintenance planning of gas pipeline. Corrosion defects occurred on the underground pipeline can be obtained by conducting periodic in-line inspection (ILI). However, little study has been done for practical use of ILI data. This paper deals with remaining lifetime prediction of the gas pipeline in the presence of corrosion defects. Because a pipeline parameter includes uncertainty in its operation, a probabilistic approach is adopted in this paper. A pipeline fails when its operating pressure is larger than the pipe failure pressure. In order to estimate the failure probability, this paper uses First Order Reliability Method (FORM) which is popular in the field of structural engineering. A well-known Battelle code is chosen as the computational model for the pipe failure pressure. This paper develops a Matlab GUI for illustrating failure probability predictions Our result indicates that clustering of corrosion defects is helpful for improving a prediction accuracy and preventing an unnecessary maintenance.

Prediction Models for Corrosion of Reinforcing Bars (철근의 부식 예측 모델에 관한 연구)

  • 김도겸;이종석;고경택;이장화;송영철;조명석
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.739-742
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    • 1999
  • A reinforcement corrosion prediction model was proposed using the results from accelerated testing and mathematical equation from the Fick's 2nd law for chloride-induced corrosion of reinforcement in concrete. The input data included the chloride concentration, mix characteristics of concrete, and environmental conditions. This model can be used to predict the chloride concentration pertaining to corrosion time and loading age for marine concrete structures. This model can also be used to predict the service life.

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Corrosion Monitoring of Reinforcing Bars in Cement Mortar Exposed to Seawater Immersion-and-dry Cycles (해수침지-건조 환경에 노출된 모르타르속 철근의 부식속도 평가)

  • Kim, Je-kyoung;Kee, Seong-Hoon;Yee, Jurng-Jae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.4
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    • pp.10-18
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    • 2018
  • The primary purposes of this study are to understand a fundamental aspect of current uniformity around a reinforcing bar (rebar) in cement mortar, and to develop an accurate monitoring method in a wet-dry cycling process with the alternative current (AC) impedance method. Three cement mortar specimens with two embedded rebars were prepared in the laboratory. As a main variable, the distance between two rebars was designed to be 10, 20 and 30 mm with the same thickness of 20 mm. To simulate the corrosion of rebars in concrete structures in a marine environment, three cement mortar specimens were exposed to 15 wet-drying cycles (24-hour-immersion in seawater and 48-hour-drying in a room temperature) in the laboratory. It was observed that the potential level shifted to a noble value during corrosion potential monitoring, which is attributed to acceleration of dissolved oxygen diffusion at the drying process. AC impedance was measured in a frequency range from 100 kHz to 1 mHz on a wet-drying process. A theoretical model was proposed to explain the interface condition between the rebars and cement mortar by using the equivalent circuit consisting of a solution resistance, a charge transfer resistance and a CPE (constant phase element). It was observed that the diffusion impedance appeared in a low frequency range as corrosion of rebars progresses. At the drying stage of the wet-drying cycles, the currents line for monitoring tended to be non-uniform at the interface of rebar/mortar, being phase shift, ${\theta}$, close to $-45^{\circ}$.

Suggestion of Deterioration Curve for New-type Coating on Atmospheric Environment by Acceleration Corrosion Test (부식촉진 실험을 통한 대기환경에서 신설 도장계의 노화곡선 제안)

  • Jeong, Young-Soo;Kim, Min-Jeong;Jeon, Seok-Hyeon;Ahn, Jin-Hee;Kim, In-Tae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.2
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    • pp.75-83
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    • 2019
  • In this study, to propose the deterioration curves of urethane, ceramic, polysiloxane and fluorocarbon coating for the steel bridge, an accelerated corrosion tests were carried out. The each coating system wes applied on the top of the specimens, and circular initial defects were introduced with different diameters with 0.5, 1.0, 3.0, 5.0 mm. An accelerated corrosion test condition was used to simulate severe corrosive environment depending on ISO 20340. The deterioration curve of each coating type was evaluated based on deteriorated area from the circular defects. In order to evaluate the coating service life of installed steel bridge using deterioration curve, the acceleration coefficient was calculated at correlation between ISO 20340 and corrosivity categories by ISO 9223 based on field corrosion rate. From test results, the propagation rate of coating deterioration area was different to diameter of circular defects. In case of urethane coating, the coating service lifes of 3% deterioration area was evaluated in 31.8, 15.8, 9.9 and 3.9 years with C2, C3, C4 and C5 category.