• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.829-839
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• 2003

Recently, the corrosion of reinforced concrete structures has received great attention related with the deterioration of sea-side structures, such as new airport, bridges, and nuclear power plants. In this regards, many studies have been done on the chloride attack in concrete structures. However, those studies were confined mostly to the single deterioration due to chloride only, although actual environment is rather of combined type. The purpose of the present study is, therefore, to explore the influences of carbonation to chloride attack in concrete structures. The test results indicate that the chloride penetration is more pronounced than the case of single chloride attack when the carbonation process is combined with the chloride attack. It is supposed that the chloride ion concentration of carbonation region is higher than the sound region because of the separation of fixed salts. Though the use of fly ash pronounces the chloride ion concentration in surface, amounts of chloride ion penetration into deep region decreases with the use of fly ash. The present study allows more realistic assessment of durability for such concrete structures which are subjected to combined attacks of both chlorides and carbonation but the future studies for combined environment will assure the precise assessment.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.617-620
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• 2008

When the RC structure repaired by patching repair method, which method refilles with patching repair material after removes degraded area, It is necessary to determine chloride ion's permeation from outside of the RC structure repaired by patching repair material. Therefore, in this study, damage from sea environment of structure was predicted, moreover, diffusion coefficient of concrete also determined to figure out rebar's corrosion and concentration of chloride ion. RCPT(Rapid Chloride Permeability Test) was used for ditermination of patching repair material's diffusion coefficient, also connection between material thickness and effect of chloride ion's permeation was examined in analytically. Results which derived by experimental test was used in FEM(Finite Element Method) and equation suggested by JSCE to predict concentration of chloride ion in different distance from surface.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1612-1614
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• 2002

본 논문에서는 엑시머 레이저 조사에 의한 이온 농도의 분포 변화를 알아보기 위해 붕소 이온이 선택적으로 주입된 비정질 실리콘 박막 위에 XeCl (${\lambda}$=308nm) 엑시머 레이저를 조사하여 붕소이온의 수평 확산 현상을 관찰하였다. 도핑 농도의 분포를 알아보기 위해 불산/질산 용액에 의한 고농도 도핑 영역의 습식 식각을 이용하여 약 $10^{18}/cm^3$ 이하의 붕소이온을 가지는 실리콘 박막의 형태를 전자주사 현미경을 이용해서 관찰하였다. 실험 결과, $200mJ/cm^2$의 레이저 에너지가 조사될 경우, 약 100nm의 수평 확산이 일어났음을 확인 할 수 있었다.

• Magazine of the Korea Concrete Institute
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• v.4 no.1
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• pp.97-106
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• 1992

Apparent diffusion coefficients of Cl- ions through hardened cement pastes(HCP), which were partly subs¬tituted blast furnace slag, fly ash and silicafume for ordinary Portland cement, were determined. Also. Cl- and OW concentration of pore solutions which were extracted from HCP and the capacities of the HCP to bind CI were determined. Diffusion coefficients of Cl- ions through HCP were increased with water cement ratio(WfC), but decreased with addition of the blending materials. On the contrary, Cl- and OH concentration of the pore solutions were reduced by adding the blending materials.

• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.481-490
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• 2012

Evaluation of chloride penetration is very important, because induced chloride ion causes corrosion in embedded steel. Diffusion coefficient obtained from rapid chloride penetration test is currently used, however this method cannot provide a correct prediction of chloride content since it shows only ion migration velocity in electrical field. Apparent diffusion coefficient of chloride ion based on simple Fick's Law can provide a total chloride penetration magnitude to engineers. This study proposes an analysis technique to predict chloride penetration using apparent diffusion coefficient of chloride ion from neural network (NN) algorithm and time-dependent diffusion phenomena. For this work, thirty mix proportions with the related diffusion coefficients are studied. The components of mix proportions such as w/b ratio, unit content of cement, slag, fly ash, silica fume, and fine/coarse aggregate are selected as neurons, then learning for apparent diffusion coefficient is trained. Considering time-dependent diffusion coefficient based on Fick's Law, the technique for chloride penetration analysis is proposed. The applicability of the technique is verified through test results from short, long term submerged test, and field investigations. The proposed technique can be improved through NN learning-training based on the acquisition of various mix proportions and the related diffusion coefficients of chloride ion.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.607-615
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• 2009

Analysis of chloride penetration into concrete is performed considering the repeated wetting and drying conditions of tidal zone, by means of the developed finite element program which enables the diffusion-convection analysis to be conducted. Heat conduction and moisture diffusion are also included in the finite element analysis program in order that their effects to chloride penetration may be considered. For the efficiency of calculation, the analyses of temperature, relative humidity and free chloride concentration are conducted successively in that order, by treating the convection of chloride due to moisture diffusion as an source or sink term. By comparing the analysis result from finite element analysis, where main variable is a wetting and drying period, with the chloride profiles from ACI Life-365 method, it is shown that the Life-365 method gives an accurate result for the submerged zone but does not consider the differences of wetting and drying period. To obtain an accurate chloride profile in the tidal zone, it is confirmed that the diffusion-convection finite element analysis should be applied.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.6
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• pp.37-45
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• 1998

In this paper, we report the first three-dimensional simulation result of the transient enhanced diffusion(TED) of dopants in the ion-implanted silicon by employing our 3D semiconductor process simulator, INPROS system. In order to simulate three-dimensional TED redistribution of dopants in silicon, the dopant distributions after the ion implantation was calculated by Monte Carlo(MC) method, followed by finite element(FE) numerical solver for thermal annealing. Excellent agreement between the simulated 3D profile and the SIMS data has been obtained for ion-implanted arsenic and phosphorus after annealing the boron marker layer at 75$0^{\circ}C$ for 2 hours. Our three-dimensional TED simulation could successfully explain the reverse short channel effect(RSCE) by taking the 3D point defect distribution into account. A coupled TED simulation and device simulation allows reverse short channel effect on threshold to be accurately predicted.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.259-260
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• 2009

Many concrete structures have suffered from carbonation or chloride ion diffusion induced reinforcement corrosion, and a number of studies have been done on these topics. Many studies were mostly confined to the single deterioration of carbonation or chloride ion, although the environment actually presents a combined condition. This paper tried to develop the approach to compute re-diffusion of de-sorbed chloride due to carbonation of concrete. This is a key for successful combined deterioration model of carbonation and chloride. It is thought that this paper can contribute to express mathematically chloride enrichment and re-diffusion of chloride at front of carbonation.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.173-182
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• 2003

Recently, the durability of concrete structures has received great attention as the number of sea-side structures, such as new airport, bridges, and nuclear power plants, increases continuously. In this regards, many studies have been done on the chloride attack in concrete structures. However, those studies were confined mostly to the single deterioration due to chloride only, although actual environment is rather of combined type. The purpose of the present study is, therefore, to explore the effects of combined deterioration due to chlorides and sulfates in concrete structures. To this end, comprehensive experimental program has been set up to observe the chloride penetration behavior for various test series. The test results indicate that the chloride penetration is more pronounced for the case of combined attack than the case of single chloride attack. The surface chloride content is found to increase with time and the diffusion coefficient for chloride is found to decrease with time. The prediction equations for surface chloride content and diffusion coefficient were proposed according to test results. The equations for chloride penetration considering the time-dependent diffusion coefficients and surface chlorides were also suggested. The present study allows more realistic assessment of durability for such concrete structures which are subjected to combined attacks of chlorides and high concentration sulfates but the future studies for combined environment will assure the precise assessment.

• Journal of the Korea Concrete Institute
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• v.14 no.5
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• pp.708-717
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• 2002

Durability is a major concern in the design and construction of concrete structures which are located in the sea environments. In particular, the combined action of chlorides, sulfates, and carbonation nay influence greatly the deterioration behavior of concrete structures. The purpose of the present study is to explore the diffusion characteristics of chloride ions in concrete structures under combined deterioration conditions. The present test results indicate that the chloride penetration into concrete structures is more pronounced under combined attacks of chlorides, sulfates and carbonation. The diffusion coefficients and surface chloride contents were found to increase under combined multiple deterioration conditions. The present study provides quantitatively the penetration and diffusion characteristics of chloride ions in concrete structures under various deterioration conditions. The results of present study may be efficiently used for the realistic design of concrete structures under combined deterioration conditions.