• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.51-52
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• 2011

This study is to propose a curing method for a concrete wall structure under severe cold climate. The curing methods of using heated cable, heated panel and insulated form were applied. Results showed that the concrete cured by the heated cable resulted in the highest temperature history and the highest strength development at 28 days. Further, it is believed that the curing methods of the heated panel and insulated form are also recommendable for the resistance of the early frost damage on the concrete in practice.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.898-905
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• 2006

In the present paper, for a quantitative assessment of early-age cracking in an RC wall, an improved analytical model is proposed. First of all, a three-dimensional finite element model for the analysis of stresses due to hydration heat and differential drying shrinkage is introduced. A discrete steel element derived using the equivalent nodal force concept is used to simulate reinforcing steels, embedded in a concrete matrix. In advance, to quantitatively calculate the cracking potential, an analytical model that can estimate the post-cracking behavior in an RC tension member is proposed Subsequent comparisons. of analytical results with test results verify that the combined use of both the finite element model for the stress analysis as well as the analytical model for the estimation of the post-cracking behavior in an RC tension member make it possible to accurately predict the cracking ,behavior of RC walls.

• 한국농공학회지
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• 제42권3호
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• pp.114-120
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• 2000

In this study a computer program considering initial imperfection of wall of axisymmetric reinforced concrete shell which show plastic deformation by large external loading is developed. initial imperfection of wall of axisymmetric reinforced concrete shell is assumed as sinusoidal curve expressed as {{{{ {W }_{i } }}}}={{{{ {W}_{0 } }}}}sin (n$\pi$y/$\ell$)y. The developed program is applied to the analysis of the dynamic response of axisymmetric reinforced concrete shell when the wall has initial imperfection. The initial imperfection of 0.0 -5.0, and 5cm and steel ratio 0.3, and 5% are tested for numerical examples. The effects of the wall initial imperfection and steel ratio on the dynamic response of the axisymmetric reinforced concrete shell are analysed, It is shown that the direction of the initial imperfection is very important factors for determining the dynamic response.

• 한국구조물진단유지관리공학회 논문집
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• 제2권3호
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• pp.212-222
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• 1998

In several structural problems, the low concrete strength of compression members has the severest influence on the structural safety. However, the repairing and strengthening techniques for compression members are not established and evaluated. This study aimed to develop and evaluate the rehabilitation techniques to obtain proper structural strength of wall with low concrete strength. The specimens with low strength of concrete were retrofitted with commonly using section increase method and epoxy bonded glass fiber techniques. The tests were executed to failure under concentric and eccentric loads. In this paper, the structural behavior and failure modes were investigated to evaluate the strengthening effects of walls subjected to compression and out-of-plane bending.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.251-258
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• 2003

The early -age behavior of base restrained reinforced concrete (RC) walls is analyzed using a three-dimensional finite element method in this study. After calculating the temperature and internal relative humidity variations of an RC wall, determination of stresses due to thermal gradients, differential drying shrinkage, and average drying shrinkage is followed, and the relative contribution of these three stress components to the total stress is compared. The mechanical properties of early-age concrete, determined from many experimental studies, are taken into consideration, and a discrete reinforcing steel derived using the equivalent nodal force concept is also used to simulate the cracking behavior of RC walls. In advance, to Predict the crack spacing and maximum crack width in a base restrained RC wall, an analytical model which can simulate the post-cracking behavior of an RC tension member is introduced on the basis of the energy equilibrium before and after cracking of concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.18-19
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• 2020

The ElectroMagnetic Pulse (EMP) destroys social infrastructure at once and causes social chaos. However, currently major infrastructures are constructed of concrete that does not have electromagnetic shielding performance. In this study, using the arc metal spraying method is used to evaluate the shielding performance and construction performance of concrete. The electro-magnetic shielding effect is measured by fabricating a shielding room with reference to MIL-STD-188-125, and the construction performance is evaluated by measuring the adhesion strength of thin metal sprayed film-concrete. As a result of the study, when the metal spraying method is applied, the shielding effect is higher than that of the special electro-magnetic shielding concrete, and it is considered to be more economical than the existing metal plate (3~5 mm).

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.23-24
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• 2020

In this study, the concrete compressive strength estimation system Concrete IoT Management System (hereinafter referred to as CIMS) was developed, and CIMS was applied to domestic field structure slabs and wall concrete to check whether CIMS is practically available and to estimate the accuracy of the initial strength estimation of concrete. As a result, it shows a very high correlation when the compressive strength of the specimen for structural management is compared with the estimated strength of CIMS in terms of integrated temperature, and it is expected to be gradually applied to domestic construction sites in the future.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.117-118
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• 2020

The masonry structure is constructed by cement mortar binding material of brick objects and uses reinforced hardware (connected hardware or wall tie) together when building. However, over time, the corrosion of reinforced steel and the deterioration of joint mortar as well as bricks cause the risk of collapse. In particular, when the externally decorated brick wall is installed on the concrete girder for each floor, the angle bracket is not constructed or corroded, the full-layer weight load is applied to the wall of 0.5B, which is an example of full-scale or collapse. The purpose of this study is to provide numerical information on the reinforcement design by experimentally studying the structural performance of concrete reinforcement brackets that reinforce the vertical load of the exterior wall.

• 콘크리트학회논문집
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• 제13권5호
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• pp.457-465
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• 2001

고층건물 콘크리트 슬래브에 발생하는 건조수축변형은 기둥이나 벽체 등의 구조부재에 의해 변형발생이 제한되고 이로 인한 인장응력이 부재의 인장강도를 초과하게 되면 균열이 발생한다. 이 논문에서는 건조수축과 크리프, 철근효과 등 콘크리트의 재료특성과 시공단계에 따른 건조수축을 고려하여 슬래브에 발생하는 응력을 산정하는 실용적인 해석방법을 제안하였다. 건조수축으로 인해 부재에 작용하는 인장응력은 건조수축변형을 등가온도하중으로 치환하여 계산할 수 있으며, 건조수축과는 달리 응력을 이완시켜 주는 크리프의 영향은 콘크리트의 탄성계수 Ec 대신에 크리프를 고려한 콘크리트의 유효탄성계수 E eff를 사용하고, 배근된 철근은 등가의 보요소로 모델링하여 해석에 반영할 수 있다. 또한 고층건물 슬래브에서 발생하는 건조수축응력은 그 층에서 발생한 건조수축량과 하부 층의 건조수축량의 차이인 유효건조수축에 의한 응력임을 고려하여 각 시공단계마다 발생하는 응력을 단계별 해석을 수행하여 구하고 이를 합산함으로서 슬래브에 최종적으로 발생하는 응력을 산정한다. 10층 규모에 예제건물을 대상으로 해석한 결과, 상부 층으로 갈수록 점차 건조수축응력이 줄어들며 전체 구조물에 발생한 응력은 저층부(1~2층)에서는 기준강도를 초과하나 3층 이상의 고층부에서는 기준강도의 27.9~92.8% 수준으로 나타났다.

• 대한토목학회논문집
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• 제38권1호
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• pp.1-10
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• 2018

변형구속부재에서 발생하는 콘크리트 부재의 초기균열은 환경에 민감한 변수가 많아서 예측하기 힘들다. 본 연구에서는 벽체-기초부재에서 수화열에 의한 초기균열 발생 조건을 모사한 시편을 제작하고 자가변형과 자체유발응력을 측정하여 재료시험으로 예측하기 힘든 균열발생 가능성을 판단하는 방법을 제시하였다. 이를 위하여 먼저 전체 구조계의 환경조건을 고려한 부재의 수화열 해석으로 초기재령 콘크리트의 온도분포를 예측하고, 해석 결과와 같이 수화열이 전자제어되는 시편을 제작하였다. 초기재령 콘크리트의 자유변형을 측정하고 이를 보상하는 인장력을 가하여 균열을 유발하는 구속응력의 크기를 구하였다. 본 연구에서 제안한 실험적 방법은 측정값의 분산이 큰 초기재령 콘크리트의 재료시험에 의존하지 않고, 초기재령 콘크리트의 수화열에 의한 온도변화, 자기수축과 릴렉세이션에 의한 자유변형량 및 구속응력을 측정할 수 있으므로 초기 균열의 발생 여부를 보다 정확하게 예측할 수 있다. 본 연구의 방법은 대형 구조물의 시공에서 본격적인 콘크리트 타설 이전에 예비실험으로 적용하면 균열예측의 정도를 높일 수 있으므로 특히 유용하다.