• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.235-238
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• 2005

The seismic fragility analyses of reinforced concrete propelled beam are performed to evaluate safety margin. The models were simulated by Latin Hyper-Cube (LHC) method considering various aging-related deterioration of RC beam. Fragility curves under various condition subjected to static load are compared. It is found that the 20$\%$ loss of top and bottom steel 15$\%$ lower than the undegraded beam in the ultimate strength. Seismic fragility analyses were performed to find out the effect of aging-related deterioration on the dynamic behaviour of RC beam.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.177-180
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• 2005

Decing agent with chloride promote frost damage of concrete structure in winter period. From the safetyside, however, it is difficult to stop using chloride. Therefore, the durable concrete is required from now on. In this paper, long-term freezing and thawing test was carried out using the freezing water containing $CaCl_{2}$ to consider the concrete scaling according to the kind of binders, such as OPC, Flyash, Slag+Fa. and Slag As a result, it was found that the degree of scaling is different with containing slag being considered to prevent the penetration chloride ion and according to each binders.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.209-212
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• 2005

Concrete structures such as buildings and bridges etc in urban areas may be damaged due to exposure to cloud water with high acidity for a long time. Acid precipitation with a pH level raining between 3.0 and 5.0 will affect concrete. A pH level of rain acid in Korea is between 4.3 and 5.3. However, few studies have been systematically investigated for the effect of rain acid on concrete structures. Therefore, this study is investigated the domestic situation of acid rain and the effect of acid rain on concrete deterioration by existing literatures as a study to analyze the effect of rain acid on concrete structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.163-166
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• 2005

In this study, an unified algorithm for the degradation analysis which considers the cracks in concrete and steel corrosion is developed and implemented into finite element analysis program. Using the program, degradation analysis on reinforced concrete structures subjected to chloride attacks was carried out with time by considering the cracks and the steel corrosion and cracking due to expansion of corroded reinforcing bars. The analytical procedure proposal in this study can be used quantitative evaluation of degradation and service life prediction.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.241-244
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• 2004

The evaluation of Single or multi-degregation of concrete coated by high performance surface penetration agency was examined through various tests, i.e., carbonation, absorption, carbonation + chloride ion and carbonation + chemical solution according to various high performance surface penetration agencies and various compressive strengths of base concrete. The 2 types of high performance surface penetration agencies were used i.e., inorganic and alcohol soluble. And 2 types of compressive strength of base concrete were used such as 21 30. MPa. The characteristics of concrete coated high performance surface penetration agency was more improved than that of non-coated concrete, and especially, water soluble inorganic agency was most effective. And if compressive strength of base concrete was low, the improved effects would be larger.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.957-960
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• 2006

In order to predict the accumulated damages by cyclic freeze-thaw, a regression analysis by the Response Surface Method (RSM) is used. RSM has merits when the other probabilistic simulation techniques can not guarantee the convergence of probability of occurrence or when the others can not differentiate the derivative terms of limit state functions, which are composed of random design variables in the model of complex system or the system having higher reliability. For composing limit state function, the important parameters for cyclic freeze-thaw-deterioration of concrete structures, such as water to cement ratio, entrained air pores, and the number of cycles of freezing and thawing, are used as input parameters of RSM. The predicted results of relative dynamic modulus and residual strains after 300 cycles of freeze-thaw for specimens show very good agreements with the experimental results. The RSM result can be used to predict the probability of occurrence for designer specified critical values. Therefore, it is possible to evaluate the life cycle management of concrete structures considering the accumulated damages by the cyclic freeze-thaw by the use of proposed prediction method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.25-33
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• 2012

In electric power transmission tower structures on offshore, implementation of life management using the event data of regular safety inspections for structural and material damages is strongly recommended. In this study, six tower structures in Sihwa Lake around Yeoungheung island were target bodies for the safety inspections. safety inspections for deterioration about each of six towers were performed about three items for steel member, five items for concrete foundation, and four items for steel-pipe pile in seawater and seawater itself. Safety inspections for steel members included the visual observations of surface appearances, the measurements of member thicknesses, and the checks of painting states. Also safety inspections for concrete foundations comprised the estimation of crack features, the evaluation of non-destructive compression strengths, and the measurements of neutralization depths and chlorides contents. For steel-pipe piles in seawater the inspections comprised the surveys of corrosion states in accordance with potential levels tests and anode tests, the analyses of photos taken on surfaces of the piles as well as the evaluation of seawater quality. A set of deterioration inspections was performed at the same positions around october of each year for three consecutive years. As a result in this study, Newly developed deterioration indexes have been applied profitably to maintain structural safety for electric power transmission towers by utilizing these event data systematically.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.401-404
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• 2008

Crack is a penetration path of harmful material such as chloride ion, and causes a serious deterioration in durability. So, the characteristics of chloride penetration are investigated for the cracked flexural concrete members using high-durable materials. For these, the flexural crack of beam specimen is introduced by transverse loading. And, Rapid Chloride Penetration Test (RCPT) and Long-term chloride penetration test are carried out to compare the chloride penetration depth. From test results when crack is happened, the chloride penetration resistance of the durable member was superior than that of the normal member. Blast furnace slag concrete member has a excellent chloride penetration resistance in long-term chloride penetration test.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.961-964
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• 2008

Fire safety is one of the important factors to be examined when applying ECC to actual concrete structures. The purpose of this study is to confirm whether the fire resistance of ECC satisfies the fire resistant requirements in order to use the fire protection material in concrete structures. Employed temperature curve are HC and RABT criterion, which are severe in various criterion of fire temperature in concrete structures. The test results show that ECC did not undergo any deterioration of fire resistance nor cause explosive spalling, which had been anticipated due to the presence of organic fibers. With comparison of current concrete and fire-resistance materials, the experimental results of ECC shows the better fire resistance performance than the other.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.565-568
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• 2008

Domestic area of most be happened chloride deicer damage. Because daily mean temperature is below 0$^{\circ}C$ from the area of domestic most. Concrete durability influence Air Content. Presently, We used to AE(air-entraining agent) for increase freeze-thaw durability. So, on concrete Air Spacing ratio used $200{\mu}m{\sim}230{\mu}m$ in Canada and under $250{\mu}m$ in Japan institution. Use of Air content has been and will continue to be a major part of concrete durability and scaling. Chloride-containing chemicals such as calcium chloride or rock salt are main deicers for the road. The prepared optimum mix concrete in this study show that freeze-thaw and scaling resistance of Non-AE(air content 1.5%) and AE (air content 4.5%, 7.2%). Solution concentrations of deicing agent were good result, and the pore system and change of hydration products is not difference comparing before freeze-thaw test.