• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.659-662
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• 2005

Electrochemical impedance spectroscopy (EIS) has been extensively used to try to evaluate the corrosion state of the steel/concrete system. This technique is attractive because, in theory, used in a wide range of frequencies, it can give detailed information about the mechanisms and kinetics of the electrochemical reactions. Impedance measurements were performed using potential control and measuring the corresponding current response. One-year-old southern exposure test. specimens were used in the current study. The effectiveness of corrosion inhibiting additives was evaluated. The corrosion current densities estimated by impedance measurements were confirmed by those determined using linear polarization techniques. The purpose of this study was to evaluate the long-term-performance potential of the corrosion inhibitors in chloride contaminated reinforce concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.281-284
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• 2008

구조물의 성능을 나타내는 성능평가에 있어 구조물의 재료 및 구조적 특성이 구조물의 성능에 미치는 영향을 분석하기 위해 고유치 해석과 비선형 정적해석을 수행하였다. 구조물의 성능에 영향을 주는 성능영향인자는 구조물의 재료적 특성과 관련하여 콘크리트 강도, 종방향 주철근, 횡구속 철근에 대하여, 구조적 특성과 관련하여 형상비, 축하중에 대하여 총 5가지로 정의하였다. 성능영향인자의 변화에 따른 분석 결과, 콘크리트 강도 증가에 따른 항복변위는 동일하지만 최대 기저전단력은 증가하였고 종방향 주철근 증가에 따른 항복변위와 최대 기저전단력은 모두 증가하였으며, 횡구속 철근 증가에 따른 항복변위와 최대 기저전단력의 변화량은 미비하였다. 형상비 증가에 따른 구조물의 항복변위는 증가하고, 최대 기저전단력은 감소하며, 축하중 증가에 따른 구조물의 항복변위와 최대 기저전단력은 감소하였다.

• 한국건축시공학회지
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• 제13권1호
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• pp.58-65
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• 2013

Currently, many high-rise buildings are built in Korea for land-efficient utilization and vista. In high-rise buildings this tall, the use of high-strength concrete is essential to reduce the cross-section of structure members and secure axial load. However, this high strength concrete is vulnerable to spalling by fire, due to the water vapor pressure caused by the very high temperature in fire. To prevent this, the main method used is to reinforce the concrete with fiber. However, there has been little research on the pumpability of fiber reinforced high strength concrete. For this reason, this study features a performance review based on the properties and pumpability of fiber reinforced high strength concrete. In addition, the parameter of rheology was measured by extracting mortar from the concrete, and friction factor was measured through a 400 m horizontal pipe pumping test using the fiber reinforced high strength concrete. The basic information on fiber reinforced high strength concrete that we obtain through the experiments and review will contribute to the field.

• 수산해양교육연구
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• 제22권4호
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• pp.576-588
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• 2010

The goal of this research was to survey a method to reinforce the efficient political function for lifelong learning when Busan metropolitan city promotes lifelong policy. To achieve this goal, the survey to reinforce the political function for lifelong education was carried out on persons in charge of lifelong education in Busan metropolitan city. The results are as follows: First, they showed high degree of perception on lifelong policy and business. Second, on a question about how much the tasks to promote lifelong education presented by our nation are needed, they answered that concrete agenda for an aging society is needed and a necessary institute to invigorate it is lifelong learning institute. Third, they answered that the policy which is necessary to be implemented as soon as possible is the development education for vocational competency, and the ratio of the perception which requires to hire education experts for life long education was high.

• 콘크리트학회논문집
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• 제11권3호
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• pp.131-140
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• 1999

This paper presents a study on the flexural ductility of reinforced concrete beams, 16beams with different concrete strength, reinforcement ratio, reinfo- rcement strength. For the purpose of inducing flexural failure, the reinforce ratio ($\rho$-$\rho$') was made not to be more than $0.75\rho$b in accordance with ACi code 318-89. From the test results, it is found that in case of a concrete strength increased from 240 to 650kg/$\textrm{cm}^2$, the displacement and curvature ductility factore are increased by about 31-231 percents. And also increased in case of increased from 650 to 900kg/$\textrm{cm}^2$, but the increasing ratio is gradually decreasing accoding to a concrete strength increases. And also found that as the Double Re-bar Ratio (($\rho$-$\rho$')/$\rho$b) increases, so the displacement and curvature ductility ratio would decrease, but in case of increased from 650 to /$900kg\textrm{cm}^2$ the decreasing ration is bigger than in case of increased from 240 to $650kg/\textrm{cm}^2$.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.296-303
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• 2000

The purpose of this study is to find inelastic behavior and ductility capacity of reinforced concrete bridge columns under earthquake. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected, due to the abrupt change in their stiffness local discontinuous deformation can be taken into account by introducing interface element. Also an analytical model is developed to express the confining effects of lateral tie which depend on the existence or nonexistence and the amounts of transverse confinement, etc. The proposed numerical method for inelastic behavior and ductility capacity of reinforced concrete bridge columns will be verified by comparison with reliable experimental results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.840-845
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• 1999

In this study, it was experimentally investigated the effectiveness of repair and strengthening methods for RC beams deteriorated under severs enviromental conditions. Polymer cement were employed to restore the sectional loss and aramid fiber-reinforced sheet was used to reinforce the surface subject to tension. Repaired and strengthened reinforced-concrete samples were subjected to loading tests. The tests revealed that the sectional restoration enhanced the loading capability of the sample structures. Additional strengthening with one aramid fiber-reinforced sheet improved 18% of yielding load and 30% of ultimate load of the structure. Reinforcing with two aramid fiber-reinforced sheets brought about an enhancement of 22% of yielding loading and 49% of ultimate load.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.81-82
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• 2009

본 연구는 띠철근 형상이 철근 콘크리트 사각형 기둥의 연성에 미치는 영향에 대해 실험을 통해 평가하고자 하였다. 철근 콘크리트 기둥에 대해 띠철근의 형상 및 배근에 관한 기준이 있음에도 불구하고 현재 일부 시공현장에서 사용되어지는 띠철근은 시공의 편의성을 위해 설계와 다른 형상으로 시공되어지고 있는 경우가 많다. 따라서 이러한 띠철근의 형상변경으로 인하여 콘크리트 기둥의 거동에 야기될 수 있는 문제점을 분석하여 안전성을 평가할 수 있는 연구가 필요하였다.

• 한국건축시공학회지
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• 제2권4호
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• pp.99-104
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• 2002

Recently, the continuous fiber materials has become more important materials to repair and to reinforce concrete structural members. Continuous fiber meshes are effective for shear and confining reinforcement and provide excellent durability when combined with high strength mortar The purpose of this study is to verify the relationship between concrete strength and the ductility of inner concrete confined laterally by continuous fiber meshes. For this study, Experimental studies were conducted by compressive members using the cast frame of high strength mortar and continuous fiber meshes. Therefore, the result shows that compressive strength and ductility has improved according to the amount of the fiber meshes, and that the lateral confined effect of members with 3- or 4-axis mesh arrangement is bigger than that of members with 2-axis mesh. These data have to be used to verify the characteristic of concrete structure members reinforced continuous fiber mesh.

• Computers and Concrete
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• 제25권1호
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• pp.29-36
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• 2020

This work presents a numerical modeling procedure to simulate the refractory concrete lining in fluid catalytic cracking units of oil refineries. The model includes the simulation of the anchors that reinforce the contact between the refractory concrete and the steel casing. For this purpose, the constitutive relations of an interface finite element are set to values that represent the homogenized behavior of the anchored interface. The parameters of this constitutive relation can be obtained by experimental tests. The model includes also multi-surface plasticity, in order to represent the behavior of the refractory concrete lining. Since the complexity of real case applications leads to high computational costs, the models presented here were implemented in a high-performance parallelized finite element platform. A case study representing a riser similar to the ones used by the refinery industry demonstrates the potential of the model.