• Title/Summary/Keyword: 부식모델

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Corrosion Level Measurement Technique for RC Reinforcement Using Non-Destructive Test Methods (비파괴기법을 이용한 철근 콘크리트 벽체 철근의 부식률 예측기법)

  • Roh, Young-Sook
    • Journal of the Korean Society for Nondestructive Testing
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    • v.31 no.1
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    • pp.24-31
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    • 2011
  • In order to measure corrosion level of reinforcement rebar in RC structures, non-destructive test methods which are concrete surface current density method and infrared thermographic technique were employed to measure corrosion levels. Experimental test parameters were various levels of corrosion states(0, 1, 3, 5, 7% of weight loss) and concrete cover depth(30 mm, 40 mm) and two different reinforcing rebar arrangements. The larger amount of concrete surface current density, the higher corrosion level in reinforcement rebar. The laboratory conditions which are ambient temperature and humidity have negligible effect on the infrared thermographical data. After analysis of current density and temperature distribution from concrete surface, corrosion level of reinforcement rebar embedded in concrete can be measured qualitatively based on the amount of electric current and heat flux.

Validation Study on Processing Grip Part of Tensile Specimen Acquired from Corroded Pipeline (부식이 존재하는 기존 노후 관로에서 인장 시편 가공 시 그립 가공 타당성에 대한 연구)

  • Nam, Young Jun;Kim, Jeong Hyun;Bae, Cheol Ho;Lim, Yun Mook
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.40 no.2
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    • pp.191-195
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    • 2020
  • In this work, tensile tests, one of the most common test method to assess the condition of a corroded pipe, were conducted. According to ASTM E8 method, the use of flat or curved uni-axial tension test is allowed under the recommendation with the usage of grips corresponding to a curvature of the pipe. However, this method is not for corroded specimen. Furthermore, in the case of performing the multiple tensile tests with various curvatures, it is desirable not to produce zigs that fit each curvatures, if merely processing the specimen grip with curvature into the flat grip can show almost identical tensile behavior. Therefore, various tension simulations were conducted first to check if there exist any differences. Also, experiments on corroded tensile specimen were conducted and compared with the FEM simulation that reflects the actual geometry acquired from the 3D scanner.

Optimization for Inspecdtion Planning of Ship Structures Considering Corrosion Effects (부식효과를 고려한 선체구조 검사계획안의 최적화)

  • Sung-Chan Kim;Jang-Ho Yoon;Yukio Fujimoto
    • Journal of the Society of Naval Architects of Korea
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    • v.36 no.4
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    • pp.137-146
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    • 1999
  • Inspection becomes to be important in the safety of structure and economical viewpoint, because structural damage accompanies lots of economical cost and social problems. Especially ship structure is composed of a lot of members and it is impossible to inspect all members continuously. The purpose of this paper is to get optimal inspection plan containing inspection time and method. Crack is one of major modes on the structural failure and can lead to collapse of structure. In this paper, the deteriorating process, which contains inspection to detect the crack before the propagation to large crack, is idealized as Markov chain model. Genetic algorithm is also used to accomplish the optimization of inspection plan. Especially, the probabilistic characteristics of cracks are changed, because ship is operating in corrosive environments and the scantling of structural members is reduced due to corrosion. Non-stationary Markov chain model is used to represent the process of corrosion in structural members. In this paper, the characteristics of indivisual inspection plan are compared by numerical examples for the change of corrosion rate, the cost due to scheduled system down and target failure probability. From the numerical example, it can be seen that the improvement of fatigue life for the members with short fatigue life is the most effective way in order to reduce total maintenance cost.

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A Study on Corrosion Product Behavior Prediction for Domestic PWR Primary System by using CRUDTRAN (CRUDTRAN을 이용한 국내 PWR 1차계통내 부식생성물 거동예측에 관한 연구)

  • Song, Jong Soon;Yoon, Tae-Bin;Lee, Sang-Heon
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.13 no.4
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    • pp.253-262
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    • 2015
  • Radionuclide deposited on the surface of several internal and external systems in a nuclear power plant is created by the activation of corrosion products from nuclear reactor structural materials and fission products. Especially, the constant contact between water and the surface corrodes the inside where primary system makes coolants and corrosion products mixed. Also, these are circulated along the systems. For comparing models, CRUDTRAN, DISER, MIGA-RT and CPAIR codes are analyzed to predict the quantity of radionuclide and corrosion product of primary reactor that are used at the stage of designing. The corrosion products behavior of domestic PWR primary system was predicted by using CRUDTRAN. This study aims to increase the reliability of corrosion product evaluation model by comparing the actual values and calculated values with the data of a Westing House-type Nuclear Power Plant.

Reduction of the Flow Accelerated Corrosion within Low Pressure Evaporator Connection Pipe by Interception of Hydrazine for Water Treatment (탈산소제 차단 수처리에 의한 배열회수보일러 저압증기발생기 연결배관내의 유동가속부식 저감)

  • Son, Byung-Gwan;Lee, Jae-Heon
    • Plant Journal
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    • v.9 no.4
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    • pp.26-30
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    • 2013
  • Based on case that HRSG low pressure steam generator tube was damaged by FAC in 500 MW A CCPP. This case analyzed the effect of application about the block of hydrazine water treatment which is applied for increasing dissolved oxygen. And also try to deduce the major factor of FAC Which is caused by lacking of dissolved oxygen of boiler feed system. After 1 year of water treatment, the figure of dissolved oxygen in the boiler feed water has increased from 0.15 ppb to 3~5 ppb and the figure of oxidation reduction potential has increased from -245 mV to 170 mV. And Iron content, the corrosion products by FAC has decreased from 18.5 ppb to 5~7 ppb. According to the result of experiment, we could able to confirm that the interception of hydrazine of water treatment is effective to reduce FAC.

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Ultimate Strength Based Reliability of Corroded Ship Hulls (부식을 고려한 선각거더의 최종강도 신뢰성)

  • Paik, J.K.;Yang, S.H.;Kim, S.K.
    • Journal of the Society of Naval Architects of Korea
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    • v.33 no.2
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    • pp.96-110
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    • 1996
  • Aging ships can suffer structural damage due to corrosion, fatigue crack etc., and possibility of catastrophic failure of seriously damaged ships is very high. To reduce the risk of loss of ships due to hull collapse, it is essential to evaluate ultimate hull strength of aging ships taking into account various uncertainties associated with structural damages. In this paper, ultimate strength-based reliability analysis of ship structures considering wear of structural members due to corrosion is described. A corrosion rate estimate model for structural members is introduced. An ultimate limit state function of a ship hull is formulated taking into account corrosion effects. The model is applied to an existing oil tanker, and reliability index associated with hull collapse is calculated by using the second-order reliability method (SORM). Discussions on structure safety of corroded ships are made.

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Corrosion Induced Long Term Crack Width Prediction for Structural Concrete Members (철근콘크리트 부재에서 철근 부식을 고려한 장기 균열폭 예측)

  • Lee, Gi-Yeol;Yang, Jun-Ho;Chung, Won-Yong;Rho, Sam-Young;Kim, Dae-Joong;Kim, Woo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2009.05a
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    • pp.199-200
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    • 2009
  • This research developed a long-term crack width prediction model based on bond characteristics that considered steel corrosion, concrete shrinkage and creep in cracking stabilized structural concrete members.

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Self-healing Polymer Coatings in Corrosive Environments (부식 환경하에서의 자가치료성 고분자 코팅)

  • Jo, Su-Hyeon
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2009.05a
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    • pp.115-115
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    • 2009
  • 하부 금속소재의 부식방지 및 코팅 도막의 자기치료 효과를 가지는 고분자 코팅을 마이크로 캡슐화된 치료물질 및 촉매의 분산에 의하여 구성하였으며 도막 손상 시에는 이러한 치료물질들이 손상부위로 흘러들어 소지를 보호하는 효과를 가지게 된다. 자기치료성 고분자는 실험실적 모델 뿐아니라 산업적으로 중요한 코팅 시스템 등에 광범위하게 응용되어질 수 있다.

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Erosion-Corrosion Behavior of Power Plant Pipe Caused by Hot Feed Water (고온 급수에 의한 파워 플랜트 배관 침식-부식 거동)

  • Bang, Sung-Ho;Lee, Jin-Won;Kim, Tae-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.6
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    • pp.739-745
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    • 2013
  • In this study, we tried to define the erosion-corrosion behavior together with the resulting effects on a pipe that is a part of a feed water circulation system according to the pipe size and hot feed water environment. An erosioncorrosion analysis was performed through the Hayduk and Minhas model based on the chemical reaction between iron and oxygen, an essential corrosive factor. The erosion-corrosion rate against the pipe diameter and feed water temperature was then evaluated by means of finite element analysis using ABAQUS. As shown in the results, the feed water temperature was the main factor influencing the erosion-corrosion rate; in particular, it was expected that the thickness of 316 stainless steel would decrease by $2.59{\mu}m$ every year in a hot water environment at $290^{\circ}C$.