• Journal of the Korea Concrete Institute
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• v.18 no.2 s.92
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• pp.233-238
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• 2006

In lifetime estimation, the FEM analysis method is proposed for predicting corrosion failure time of concrete structures exposed to sea-water. This study shows that the corrosion rate of rebar in artificial pore solution can be transferred to the corrosion rate of rebar in concrete using the relationship between pore volume and concrete volume by Jennings' model. And this study considered the pitting corrosion effects of reinforcement bar on corrosion failure analysis, rebar size to cover depth and nonlinear crack analysis. These analysis results have good accordance with the experimental results of Williamson's work. This methodology can be applied to lifetime prediction procedure of reinforced concrete structures and also gives more reasonable results of concrete cover failure time estimation of reinforced concrete structures exposed to sea-water.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.1
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• pp.46-51
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• 2007

In this study, test results for fatigue crack propagation of Al-2024-T3511 are presented considering corrosion effects, and fatigue lifes are compared for the cases of corrosion and non-corrosion. Higher corrosion environments show lower fatigue life and faster crack growth. To predict the corrosion fatigue life, a corrosion factor concept is newly introduced and applied in Paris' law. The predicted results show good agreement with experimental data and this corrosion fatigue model can be successfully used for the prediction of fatigue life of aluminum structure with corrosion effects.

• Journal of the Korean Institute of Gas
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• v.7 no.2 s.19
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• pp.1-6
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• 2003

In this work, procedure evaluating failure modes such as pipe rupture, large scale leak, and small scale leak was suggested using equations to assess remaining strength by corrosion failure. Additionally, the method to predict probability of failure was suggested according to the aforementioned failure modes, and by combining data on corrosion rate, probability of long-term failure can be induced. This work will be very useful in predicting lifetime or exchanging period of pipeline.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.260-266
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• 2009

Non-revenue water reduction(NRW) technologies are implemented to evaluate and manage leakages scientifically in water distribution systems under local governments. A development of quantitative leakage indicator by measuring minimum night flow, pressure control policy by installation of PRV(pressure reducing valve) and the establishment of leakage prevention schemes by residual life modeling of deteriorated water pipes are reviewed and studied. Estimation models of allowable leakage are developed by measuring and analyzing minimum night flow at residential and commercial area in Nonsan city, which is suggested from UK water industry and can improve an existing leakage indicator for the evaluation of non-revenue water. Also, pressure control method is applied and analyzed to Uti distribution area in Sacheon city in the operation aspect. As results, $466\;m^3/day$ of leakage can be reduced and it is expected that 113million won of annual cost can be saved. In the part of corrosion velocity and residual life assessment, non-linear prediction models of residual thickness are proposed by assessment of corrosion velocity based on exposure years, soil and water quality etc., since the deteriorated water pipe play a major role to increase leakage. It is expected that collection data and analyzing results can be applied effectively and positively to reduce non-revenue water by accumulating surveying data and verifying the results in the business field of water distribution systems under local governments.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.907-913
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• 1998

Corrosion behavior of steel reinforcements embedded in concrete containing various chloride ion concentrations was investigated by an electrochemical impedance spectroscopy(EIS). Chloride ions were introduced into the concrete by dissolving the NaCl and $CaCl_2$ in the water with a given weight of cement. Based on the impedance parameters measured by EIS, more complete equivalent circuit, a schematic physical model, and the mechanism of concrete reinforcement corrosion were suggested. By the implement of experimental impedance parameters obtained from the model with corresponding CNLS-fitting data, the corrosion rate of steel reinforcement with chloride ions could be predicted.

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.16-22
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• 2016

Coating pipe(PLP) has been generally used in buried site for protecting the corrosion. To prevent the damage by occurring the defect, other construction or execution works, an anti-oxidation environment was forcibly made by using protective potential. Coating and protective potential are applied simultaneously, but corrosion rate or defects are not easy to observe because soil composition has many uncertainty. Also, defect of coating pipe can not be directly observed. A corrosion coupon can easily measure a corrosion rate directly. The corrosion rate was measured with 6 scenarios using corrosion coupon during about 1 year(6 scenarios are based on soil type and protective potential or not in this research. Resultingly, the corrosion coupon has not occurred in the case of protected by potential current, but corrosion has occurred in a non-protected site. The corrosion rate was measured at least in the clay, and the propensity of corrosion rate was similar in other soil(sand and loams). The local corrosion has occurred in the clay because of high water content. On the other hand, general corrosion was occurred in sand and loams. Commonly, sand is not to corrosive soil. Although, corrosion occurred in sand can be estimated by chemical component and valid with chemical analysis report.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.5
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• pp.481-486
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• 2011

It is important to predict the behavior of a liquid film around a rotating cylinder in the film coating process of the steel industry. When the cylinder rotates, the behavior of the liquid film on the rotating cylinder surface is influenced by the cylinder diameter, the rotation speed, the gravitational force, and the fluid properties. These parameters determine the liquid film thickness and the rise of the film on the cylinder surface. In the present study, the two-phase interfacial flow of the liquid film on the rotating cylinder were numerically investigated by using a VOF method. For various rotation speeds, cylinder diameters and fluid viscosities, the behavior of liquid film on the rotating cylinder were predicted. Thicker film around the rotating cylinder was observed with an increase in the rotation speed, cylinder diameter, and fluid viscosity. The present results for the film thickness agreed well with available experimental and analytical results.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.08a
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• pp.104-117
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• 2004

Dmitri Donskoi, which went down during the Russo-Japanese War occurred 100 years ago, was found by using geophysical exploration techniques at the 400 m water depth of submarine valley off Jeodong of Ulleung Island. In the submarine area with the rugged seabed topography and volcanic seamounts, in particular, the reliable seabed images were acquired by using the mid-to-shallow Multibeam exploration technique The strength of corrosion (causticity) of the sunken Donskoi, measured by the electrochemical method, decreased to 2/5 compared with the original strength.