• 콘크리트학회지
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• 제10권6호
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• pp.169-178
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• 1998

고성능 belite 시멘트 콘크리트에 대한 부착특성에 대하여 코\ulcorner리트의 강도, 슬럼프, 배근위치, 피복두께 등의영향요인을 보단부시험체와 이음길이 보시험체를 통해 연구하였다. 동일한 압축강도의 1종 보통 포틀랜드 시멘트 콘크리트에 비해 부착강도는 약 10%증가하였고 압축강도 600kg/$\textrm{cm}^2$의고강도 belite 콘크리트에서 부착강도가 대체로 {{{{ SQRT { f'c} }} }}에 비례하였다. 유동성에 있어서 높은 슬럼프에 비해 ACI 318-95 규준에서 제시하는 상부근 계수 1.3이하의범위에 있었으며 이것은 고유동 belite 콘크리트가 블리이딩이나 골재분리가 적은 것으로 보여졌다. 또한 고강도 belite시멘트 콘크리트를 사용한 이음길이 보시험체에서 부착강도는 기존 예측식의 값보다다소 높게 나타났으며, 실리커흄, 플라이애쉬를 사용한 고강도 콘크리트 부착강도의 기존연구결과인 낮은 값과 차이를 보였다. 이상의 결과로 고유동, 고강도 belite 시멘트 콘크리트는 철근과의 부착성능이 다른 재료에 비해 양호한 것으로 나타났다.

• 한국건축시공학회지
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• 제2권3호
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• pp.123-130
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• 2002

Recently, it is being studied on the high strength concrete in many laboratories and being applied to the construction field actually. But non-destruction testing equation that to be proposed about normal strength concrete in Japan has been using because the systematic study results for the estimation of compressive strength of high strength concrete do nit exist. So it is essential to suggest the non-destruction testing equation for the estimation of compressive strength of high strength concrete. This is an experimental study to analyze and investigate the non-destruction testing equation for the estimation of compressive strength of high strength concrete. The results are as follows; The relation between rebound number, pulse velocity and compressive strength of high strength concrete have lower coefficient than combined method of rebound number and pulse velocity. Also new non-destructive testing equation for the estimation on the compressive strength of high strength concrete was suggested in this study, and it is considered that these equations have possibility to be applied in domestic construction field.

• 콘크리트학회논문집
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• 제17권6호
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• pp.1075-1084
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• 2005

The compressive strength of concrete is commonly used criterion in producing concrete. However, the tests on the compressive strength are complicated and time-consuming. More importantly, it is too late to make improvement even if the test result does not satisfy the required strength, since the test is usually performed at the 28th day after the placement of concrete at the construction site. Therefore, accurate and realistic strength estimation before the placement of concrete is being highly required. In this study, the estimation of the compressive strength of concrete was performed by probabilistic neural network(PNN) on the basis of concrete mix proportions. The estimation performance of PNN was improved by considering the correlation between input data and targeted output value. Improved probabilistic neural network was proposed to automatically calculate the smoothing parameter in the conventional PNN by using the scheme of dynamic decay adjustment (DDA) algorithm. The conventional PNN and the PNN with DDA algorithm(IPNN) were applied to predict the compressive strength of concrete using actual test data of two concrete companies. IPNN showed better results than the conventional PNN in predicting the compressive strength of concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.241-246
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• 2000

In the strut-tie model design of structural concrete, the importance of the effective strength of concrete strut has been overlooked by many practitioners. The authors believe that the effective strength of concrete strut is an important factor not only in determining steel tie forces but also in verifying the nodal zone strength and geometric compatibility condition of a selected strut-tie model. This study evaluate the effect of the effective strength of concrete strut on structural concrete design by applying the different effective strut strengths to the strut-tie model design of a post-tensioned anchorage zone and a continuous concrete deep beam.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 가을 학술발표회 논문집
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• pp.232-236
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• 1993

The Tunnel Form(T/F) system instead of traditional euro form has been tried to reduce construction duration and to improve concrete quality in reinforced concrete wall type apartment construction. To find the relationship for concrete compressive strength between cylinder mold and slab, the different curing locations of concrete cylinder mold in the room have been investigated. The test results showed that the compressive strength of the cylinder concrete with middle-upper location in the room was most near concrete compression strength with respect to slab concrete strength.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.160-165
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• 1996

The tensile of concrete in one of important factor for study of reinforced concrete as well as prestressed concrete structures. In many countries, a numerous experimental studies are being undertaken to investigate correlation between compressive and tensile strength of concrete. This study is focused on identifying the relationship between the compressive strength and torsional tensile strength of concrete and, on crack of RC and PC structure.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.397-402
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• 2001

Microstructural characteristics such as hydrates and porosity greatly influence the development of concrete strength. In this study, a strength estimation model for early-age concrete considerig, the microstructural characteristics was proposed, which considers the effects of both an increment of degree of hydration and capillary porosity on a strength increment. Hydration modeling and compressive strength test with curing temperature and curing ages were carried out. By comparing test results with estimated strength, it is found that the strength estimation model can estimate compressive strength of early-age concrete with curing ages and curing temperature within a margin of error.

• 콘크리트학회논문집
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• 제15권1호
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• pp.155-161
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• 2003

This paper presents experimental and analytical results of glass fiber-reinforced concrete (GFRC) and polypropylene fiber-reinforced concrete (PERC) to investigate the relationship between tensile strength and compressive strength based on the split cylinder test (ASTM C496) and compressive strength test (ASTM C39). Experimental studies were performed on cylinder specimens having 150 mm in diameter an 300 mm in height with two different fiber contents (1.0 and 1.5％ by volume fraction) at ages of 7, 28 and 90 days. A total of 90 cylinder specimens were tested including specimens made of the plain concrete. The experimental data have been used to obtain the relationship between tensile strength and compressive strength. A representative equation is proposed for the relationship between tensile strength and compressive strength of fiber-reinforced concrete (FRC) including glass and polypropylene fibers. There is a good agreement between the average experimental results and those calculated values from the proposed equation.

• Structural Engineering and Mechanics
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• 제58권6호
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• pp.989-999
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• 2016

Moist curing of concrete is a time consuming procedure. It takes minimum 28 days of curing to obtain the characteristic strength of concrete. However, under certain situations such as shortage of time, weather conditions, on the spot changes in project and speedy construction, waiting for entire curing period becomes unaffordable. This situation demands early strength of concrete which can be met using accelerated curing methods. It becomes necessary to obtain early strength of concrete rather than waiting for entire period of curing which proves to be uneconomical. In India, accelerated curing methods are used to arrive upon the actual strength by resorting to the equations suggested by Bureau of Indian Standards' (BIS). However, it has been observed that the results obtained using above equations are exaggerated. In the present experimental investigations, the results of the accelerated compressive strength of the concrete are used to develop the regression models for predicting the short term and long term compressive strength of concrete. The proposed regression models show better agreement with the actual compressive strength than the existing model suggested by BIS specification.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.323-328
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• 1997

The strength of concrete depends on factors of materials, composition and manufacturing method. Among these factors, preparatory experiments are to consider and analyze the factors on compressive strength of ultra-high strength concrete according to types of aggregate, binder content, water-binder ratio, and curing methods. And the final experiment to develop the ultra-high strength over 3,000kgf/$\textrm{cm}^2$ is based on these preparatory experiments. As the result of this final expriment. We could manufacture the ultra-high strength concrete with a marvelous compressive strength concrete with a marvelous compressive strength of 3,116kgf/$\textrm{cm}^2$. This study is to compare and analyze the manufacturing system of ultra-high strength concrete of 3,116kgf/$\textrm{cm}^2$ compressive strength in the side of material development of construction industry.