• Computers and Concrete
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• v.11 no.4
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• pp.305-316
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• 2013

This paper aims to study the effect of measurement methods and cracking on chloride transport of concrete materials. Three kinds of measurement methods were carried out, including immersion test, rapid migration test and steady-state migration test. All of these measurements of chloride transport show that chloride ion diffusion coefficient decreased with the reduction of water to cement ratio. Results of the immersion test were less than that of rapid migration test and steady-state migration test. For the specimen of lower water to cement ratio, the external electrical field has little effect on chloride binding relatively. Compared with the results obtained by these different measurement methods, the lower water to cement ratio may cause smaller differences among these different methods. The external voltage can reduce chloride binding of concrete, and the higher electrical field made a strong impact on the chloride binding. Considering the effect of high voltage on the specimen, results indicate that results based on the steady-state migration test should be more reasonable. For cracked concrete, cracking can accelerate the chloride ion diffusion.

• Computers and Concrete
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• v.13 no.1
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• pp.117-133
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• 2014

This study presents a rapid method for determining the steady state migration coefficient of concrete by measuring the electric current. This study determines the steady state chloride migration coefficient using the accelerated chloride migration test (ACMT). There are two stages to obtain the chloride migration coefficient. The first stage, the steady-state condition was obtained from the initial electric current at the beginning of ACMT. The second stage, the average electrical current in the steady state condition was used to determine the steady state chloride migration coefficient. The chloride migration coefficient can be determined from the average steady state current to avoid sampling and analyzing chlorides during the ACMT.

• Journal of Navigation and Port Research
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• v.34 no.10
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• pp.787-792
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• 2010

It is necessary to predict the penetration of chloride ions for designing RC construction in marine environments. However, it takes a long time to obtain chloride migration coefficients. Therefore, the rapid chloride penetration test (RCPT) is generally used to shorten the test time. But there is a difference between chloride migration coefficients determined by rapid chloride penetration tests and those based on exposure in marine environments. In this study, we evaluated the effect on the chloride ion migration coefficient caused by a change in voltage and NaCl concentration. We also compared the relationship between the chloride ion migration coefficient by RCPT and that by exposure in marine environments. As a result of the experiments, we found that there is only a small change in the experimental factors based on changes in voltage and NaCl concentration and since they are so small, we can conclude that they are in the range of experimental error and test results from chloride ion migration coefficients by RCPT and exposure were very different from each other. In the exposure experiments, when the water-cement ratio was increased, the smaller fine air gaps in concrete affected the chloride ion migration coefficient.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.31-32
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• 2011

The purpose of this study is to investigate the amount of chloride penetration into concrete finishing materials. Chloride ion migration test was used rapid infiltration method proposed by 'NT-Build 492'. The kind of coated finishing material is 'None-finished(N)', 'Cement Mortal(M)', 'Water based paint(P)', 'Bone-Tile(B)', 'Repair Mortal(R1)' in this paper.

• International Journal of Concrete Structures and Materials
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• v.4 no.2
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• pp.105-108
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• 2010

In order to determine the effect of the use of limestone sand on chloride ion ingress in mortar, specimens were cast with two different sands: siliceous sand (used as reference) and limestone crushed sand (used for this study). To compare and assess the resistance of this mortar to chloride penetration, two different diffusions tests were employed: slow migration and rapid migration (AASHTO test). In this study, calculation of the effective diffusion coefficient is proposed using a model based on Nernst. Planck equation. The diffusion coefficients from each sample were compared. The results for all tests show that the diffusion coefficients for siliceous sand mortar are larger than those obtained with limestone sand. It appears also that the diffusion coefficient varies as a function of the W/C ratio.

• Computers and Concrete
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• v.9 no.5
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• pp.375-387
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• 2012

The objective of this investigation was to develop rules for automatic categorization of concrete quality using selected artificial intelligence methods based on machine learning. The range of tested materials included concrete containing a new waste material - solid residue from coal combustion in fluidized bed boilers (CFBC fly ash) used as additive. The rapid chloride permeability test - Nordtest Method BUILD 492 method was used for determining chloride ions penetration in concrete. Performed experimental tests on obtained chloride migration provided data for learning and testing of rules discovered by machine learning techniques. It has been found that machine learning is a tool which can be applied to determine concrete durability. The rules generated by computer programs AQ21 and WEKA using J48 algorithm provided means for adequate categorization of plain concrete and concrete modified with CFBC fly ash as materials of good and acceptable resistance to chloride penetration.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.427-432
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• 1999

An electrci method for the rapid determination of chloride diffusion coefficient in concrete is proposed considering the electrical migration term in the Nernst-Plank equation. The experimental set-up for this method is basically that for PD index by Dhir, excluding some change in the experimental parameter values in consideration of reliability, simplicity and rapidity of the accelerated test method. Experimental results show that 30mm of specimen thickness, 10 volt of supplied potential, and 5M of chloride ion concentration are optimal

• Environmental Mutagens and Carcinogens
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• v.17 no.2
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• pp.71-77
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• 1997

The single cell gel electrophoressis(SCGE) assay, also known as the comet assay, is a rapid, simple, visual and sensitive technique for measuring and analysing DNA breakage in mammalian cells. The SCGE or comet assay is a promising test for the detection of DNA damage and repair in individnal cells. It has widespread potential applications in DNA damage and repair studies, genotoxicity testing and biomonitoring. In this microgel electrophoresis technique, cells are embedded in agarose gel on microscope slides, iysed and electrophoresed under alkaline conditions. Cells with increased DNA damage display increased migration of DNA from the nucleus towards the anode. The length of DNA migration indicates the amount of DNA breakage in the cell. The comet assay is also capable of identifying apoptotic cells which contain highly fragmented DNA. Here we review the development of the SCGE assay, existing protocols for the detection and analysis of comets, the relevant underlying principles determining the behaviour of DNA and the potential applications of the technique.

• Korean Journal of Veterinary Research
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• v.45 no.2
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• pp.191-197
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• 2005

An immunochromatographic (IC) strip for the rapid detection of Salmonella spp. in the enriched sample was developed. Affinity purified Salmonella polyclonal antibody was conjugated with 40 nm colloidal gold particles which were prepared by citrate method in our laboratory. The antigen-antibody-gold complex was captured by Salmonella antibody attached to test line of nitrocellulose membrane during the capillary migration of sample. Specificity of the IC strip was calculated to be 100% (12/12) and sensitivity was 97.6% (41/42) in the test with pure cultured bacteria. Salmonella was artificially inoculated into raw pork macerated with enrichment broth. And then it was 10-fold diluted from $5.2{\times}10^{8}CFU/ml$ to 5.2 CFU/ml. The IC strip could detect $5.2{\times}10^{6}CFU/ml$ before enrichment. However, the lowest limit of detection was 5.2 CFU/ml after overnight incubation. The results indicated that the IC assay was a rapid, economical and simple method with high specificity and sensitivity for the detection of Salmonella spp. without using any equipment.

• Journal of Korean Society for Quality Management
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• v.25 no.2
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• pp.15-27
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• 1997

This paper describes a highly accelerated life test (HALT, USPCBT) method for rapid qualification testing of STH PWB(Silver Through Hole Printed Wiring Boards). This method was carried out to be an alternative to the present time-consuming standard 1344 hours life testing(THB). The accelerated life test conditions were $121^{\circ}C$/95%R.H. at 50V bias and without bias. Their results are compared with those observed in the standard 1344 hours life test at $40^{\circ}C$/95%R.H. at 50V bias and without bias. The studies were focused on the samples time-to-failure as well as the associated conduction and failure mechanisms. The abrupt drop of insulation resistance is due to the absorption of water vapour. And the continuous drop of insulation resistance is due to the Ag migration. The ratios of time-to-failure of HALT(USPCBT) to THB were 25 and 11 at 50V bias and without bias respectively.