• Journal of the Korea Concrete Institute
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• v.13 no.3
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• pp.277-284
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• 2001

Hardened concrete contains pores of varying types and sizes, and therefore the transport of air through concrete can be considered. The rate of permeability will not only depends on the continuity of pores, but also on the moisture contents in concrete and finishing material on concrete. Also it knows that the durability of reinforced concrete structure is concerned with air permeability which effects on the carbonation occurred by invasion of CO2 gas and the corrosion of steel bar occurred by O$_2$. In this paper, the effects of curing conditions and finishing materials on carbonation and air permeability are investigated according to the accelerated carbonation test. As results, carbonation velocity and air permeability are effected by curing conditions and finishing materials, and air permeability coefficient is effected by moisture content. Also the relationship between carbonation velocity coefficients and air permeability coefficients has been quite well established.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.141-147
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• 2010

The rate of carbonation is usually low in the natural environment due to the low $CO_2$ concentration in the atmosphere. Therefore, investigation of carbonation is usually conducted under accelerated testing conditions so as to speed up the process. This study is to predict carbonation progress by mathematical model, based on the diffusions of $CO_2$ and its reaction with $Ca(OH)_2$ in carbonation progressing region, in the atmosphere. To predict of carbonation progress in the atmosphere, we adopted a diffusion coefficient of $CO_2$ that agreed well the experimental value obtained by the accelerated carbonation test. Consequently the model can predict the rate of carbonation of concrete exposed in the atmosphere regardless of finishing materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.569-572
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• 2008

A series of the field inspection and the test have been performed on 297 existing bridges, in order to evaluate the bridges since 1995. In this study, based on the test results of the in-depth inspection, the identification of the extent of the chloride content and the incidence of the carbonation depth was conducted, and construction age and member type, environment condition were considered in this analysis. According to simple regression of the tested carbonation depth, the carbonation rate coefficient of the bridges in metropolises was estimated 5.41 and greater than 3.89 and 1.91 in case of marine condition and etc respectively. After measuring chloride content in concrete member, it was concluded that the chloride content of the bridges in marine condition was 4.7 times greater than the others. Especially, slabs had the most highly chloride content and it was estimated 0.709 $kg/m^3$

• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.41-44
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• 2004

Recently, in the case of domestic, for all that the deterioration environment about the carbonation of reinforced concrete structures is accelerated, systematic diagnosis and researches are not completed. And the selection techniques of repair material and method used under the situation that the indicator and the performance evaluation method are nor established are dependant on existing experience. Therefore, the purpose of this study is intend to present fundamental data for the reasonable selection of repair material and method. durability design and longevity on the deteriorated reinforced concrete structures, through computing the carbonation depth and velocity coefficient by accelerating carbonation test under various accelerating conditions and investigating the application of carbonation evaluation method. The results of this study are as follow; The resistances to carbonation are increased when the W/C ratio if lower and the treatment of surface coating is executed. And the carbonation depth and velocity coefficient according to accelerating carbonation test conditions are increased when the conditions of temperature, relative humidity and $CO_2$density are higher individually.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.793-801
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• 2005

This study investigates fundamental properties of recycled aggregate concrete which incorporated 100% recycled coarse aggregate and various amount of recycled fine aggregate. In addition, for the purpose of the improvement of long term strength and durability, a part of cement was replaced with fly ash. Compressive strength and resistance to chloride ion penetration and carbonation were investigated. When the coarse aggregate was completely replaced with the recycled the replacement ratio of the fine aggregate with the recycled was recommended to be limited below 60% in the consideration of strength. The strength of the steam-cured specimen was very comparable to the wet-cured at 28 days. As fly ash content increased the resistance to chloride ion penetration was increased. The chloride ion penetrability based on the charge passed was found to be low at 21 days and very low at 56 days, respectively. Carbonation depth and carbonation velocity coefficient increased as the fly ash content increased and the relationship between the carbonation depth and recycled fine aggregate replacement ratio was not clear. Up to 28days, however, the measured carbonation depth was mostly less than 10mm which could be considered as low.

• Journal of the Society of Disaster Information
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• v.13 no.3
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• pp.332-339
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• 2017

In the case of aged structures, the information of the structure is often lost after the completion of construction, and there is a great difficulty in predicting the durability life of the structure due to the lack of information on concrete formulations. In this study, the durability of concrete specimens was evaluated by various field and indoor test methods based on the core specimens collected from the field, and the durability life of the concrete structures was predicted by using the FEM analysis technique.As a result, the neutralization rate coefficient was $5.38E-6(cm^2/day)$ and the rate of progress was low. And the possibility of complex deterioration due to carbonation and salting was found to be very low.

• Journal of the Korea Institute of Building Construction
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• v.4 no.1
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• pp.119-126
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• 2004

Generally, reinforced concrete is one of the most commonly used structural materials and it prevents corrosion of steel bar by high pH of interior, But, as time elapsed, reinforced concrete structure become deteriorated by many of combined deterioration factors and environmental conditions. And, there are large number of deteriorate mechanism of the reinforced concrete structure and it acts complexly. It is recognized that steel bar corrosion is the main distress behind the present concern regarding concrete durability. In this study, to institute combined deterioration environments, established acceleration condition and cycle for combined deterioration environments has a resemblance to environments which are real structures placed. After that to confirm corrosion properties of reinforced concrete due to permeability with covering depth and types of surface cover under combined deterioration environments, measured carbonation velocity coefficients, chloride ion diffusion coefficients, water absorption coefficients, air permeability coefficients and electric potential, corrosion area ratio, weight reduction, corrosion velocity of steel bar. The results showed that an increase in age also decrease carbonation velocity coefficients, increase Chloride ion diffusion coefficients and increases water absorption coefficients. As well, an increase in age also increases corrosion of steel bar. Data on the development of corrosion velocity of steel bar with types of surface cover made with none, organic B, organic A, inorganic B, and inorganic A is shown. As well, permeability and corrosion velocity of steel bar with covering depth is superior to 10mm than 20mm. And it is confirmed permeability and corrosion properties of steel bar are closely related.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.291-291
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• 2011

플라즈마에 노출된 재료 표면의 온도 증가는 다음과 같은 요인에 의해서 결정된다. 이온의 충돌에 의한 역학적 에너지, 이온의 중성화, 라디칼의 안정화에 의한 에너지 방출(잠열, latent heat), 플라즈마에서 방출된 빛의 흡수. 이중 식각을 위한 기판 바이어스에 의해서 주로 결정되는 이온 충돌 에너지와 잠열의 방출이 300 mm wafer용 유도 결합 플라즈마 식각 장치에서 소스 전력과 바이어스 전력에 따라서 어떻게 변화하는지 전산 유체 역학 모사 프로그램인 CFD-ACE를 이용하여 상용 식각 장비인 AMAT사의 DPS II를 대상으로 온도 분포의 변화를 계산하였다. 실험 결과와 비교를 위하여 다섯 곳에(상, 하, 좌, 우, 중심) 열전대를 부착한 온도 측정 웨이퍼를 기판의 위치에 설치하고 여러 가지 실험 조건에 대해서 온도의 변화를 측정하였다. Ar 10 mTorr에서 2열 병렬 안테나의 전력을 300 W에서 시간에 따른 온도의 변화를 측정하였다. 이때 wafer의 평균 온도는 $28.9^{\circ}C$에서 $150^{\circ}C$까지 12분 내에 상승하였으며 최고 온도에 도달한 다음에는 거의 일정하게 유지 되었다. Si의 식각에서 온도의 영향을 가장 크게 받는 반응은 F 라디칼에 의한 Si의 직접 식각이며 Arrhenius 식의 형태로 표현하면 0.116*exp (-1250/T)의 형태로 된다. 문헌에 보고된 계수를 이용해서 $29^{\circ}C$의 식각 속도와 플라즈마에 의한 가열 최고 온도인 $150^{\circ}C$ 때의 값을 비교해보면 3.3배의 차이가 난다. 따라서 4%내의 식각 균일도를 목표로 하는 폴리 실리콘 게이트 식각 장비의 설계에서는 플라즈마에 의한 가열 불균일을 상쇄 할 수 있는 히터와 냉각 구조의 최적 설계가 필요하다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.501-504
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• 2008

A concrete carbonation model has been constructed that takes account of the diffusion of carbon dioxide through a coating and reaction with calcium hydroxide, and this model has been validated by an accelerated carbonation experiment. (1) By using values for the coatings calculated on the basis of a diffusion.permeation theory as input data for the analysis of diffusion.reaction carbonation in an unsteady state, the effect of the coatings in reducing carbonation can be represented with high accuracy. (2) Through a sensitivity analysis of the diffusion.reaction carbonation model and the experimental results, we found that the diffusion coefficient of calcium hydroxide shows a high interrelationship at 1e-12($m^2/s$). The reaction rate constant for carbonation shows a high interrelationship at 5e-5($m^3/mol/s$).