• 한국산학기술학회논문지
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• 제17권6호
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• pp.693-699
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• 2016

본 연구는 분말형 수축저감제를 이용하여 일반 강도를 갖는 콘크리트에서 $350{\mu}{\varepsilon}$ 이하의 초수축 특성을 얻게 하는데 필요한 결합재의 치환률을 평가하였다. 또한 이를 바탕으로 4변지지 구속된 조건에서 실대형 벽체를 통해 분말형 수축 저감제의 첨가 유무에 따른 수축 특성을 측정하고 균열저감 특성을 평가하였다. 콘크리트의 기초 물성은 슬럼프와 공기량을 측정하였으며, 수축 특성은 길이 변화를 측정하여 평가하였다. 수축 저감을 위해 최대 플라이애시는 20%까지 유효하였으며, 고로슬래그를 사용하거나 3성분계로 치환하는 경우 수축 특성에 불리한 것으로 평가되었다. 플라이애시와 고로슬래그 및 3성분계 바인더 비율에 따른 일반 강도 콘크리트의 건조수축 길이 변화 특성에 영향을 주는 인자의 특성을 분석하고, 도출된 배합에 대해 분말형 수축저감제를 적용하여 그 균열 계측 결과를 통해 그 유효성을 검증 연구를 수행하였다. 또한 도출된 배합에 적용된 수축저감 콘크리트의 특성은 넣지 않은 경우에 비하여 약 60% 수준으로서 $350{\mu}{\varepsilon}$ 이하의 수축저감 특성을 보였다. 4변지지 구속 조건을 고려한 수축균열 유도실험을 통해 기존의 배합대비 균열발생 저감 효과를 검증하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.368-373
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• 1998

Prepackaged system consists out of a dry mix which contains cement, sand, redispersible polymer powder and admixtures in the right proportions. The purpose of this study is to evaluate the quality of prepackaged-type polymer-modified mortar products using redispersible poly(ethylene-vinyl acetate)(EVA) powder. Polymer-modified mortars using the redispersible polymer powder with powdered with powdered shrinkage-reducing agent were prepared with cellulose fiber contents of 0, 0.5, 1.0% and shrinkage-reducing agent contents of 0, 4%, and tested for drying shrinkage, strength, adhesion in tension, water absorption. From the test results, the prepackaged-type polymer-modified mortar products with 4% of shrinkage-reducing agent content give good properties. and that their properties largely depends on the shrinkage-reducing agent content rather than the cellulose fiber contents.

• 콘크리트학회논문집
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• 제17권5호
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• pp.853-856
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• 2005

A low water/cement ratio leads to autogenous shrinkage of cement paste at an early age. This autogenous shrinkage is related to the change of relative humidity in the pore structure that is formed during the hydration process. The relationship between autogenous shrinkage and relative humidity change are relatively well defined today, but the effects of temperature on autogenous shrinkage, relative humidity, and pore structures have been studied less systematically. This study focused on correlating alterations of these properties of cement paste hydrated at constant temperatures of 20, 40, and $60^{\circ}C$. The test results clearly indicate that increasing curing temperature resulted in increased porosity, particularly for pores between 5 to 50 nm as measured by MIP, and increased autogenous shrinkages, as a consequence of a reduction of relative humidity at early ages.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.163-164
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• 2020

The purpose of this study was to evaluate the shrinkage properties of a tile reinforced with epoxy resin, which has the advantages of high adhesion and low shrinkage, and causes a hardening reaction by chemical bonding with cement mortar. As a result, since the epoxy resin adhesive suppresses the moisture evaporation of the mortar, the drying shrinkage of the mortar itself is reduced, accordingly, the shrinkage of the tile itself is greatly reduced, and it is thought that it is possible to prevent a decrease in adhesion due to shear stress.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.143-144
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• 2015

In this research it was attempted to analyze the general engineering properties of low cement mortar according to the type of setting accelerator and substitution rate, when 1% substitution rate for setting accelerator was used a high rate of compressive strength manifestation was shown and that the WS-10 type setting accelerator was appropriate. For the rate of change of length, when 3% substitution rate for setting accelerator was used, it was shown that due to initial expansion the shrinkage compensation was not significant, and when taking into consideration strength and shrinkage, 1% of WS-10 was shown to be appropriate.

• 한국염색가공학회지
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• 제20권4호
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• pp.43-52
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• 2008

Wool fabric was treated with oxygen low-temperature plasma (LTP) and dichloroisocyanuric acid. The effect of dimensional stability (relaxation shrinkage, hygral expansion, felting shrinkage), tensile strength and elongation, crease recovery, and hand of wool fabric between LTP, DCCA treated wool fabrics and control wool fabric were investigated. SEM photograph showed that a little micro crack was formed on the fiber surface by plasma treatment with hard condition and epicuticle scale was damaged by DCCA treatment. Felting shrinkage, tensile strength and total hand value were much different in each samples.

• 한국산학기술학회논문지
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• 제17권4호
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• pp.296-302
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• 2016

콘크리트의 내구성 저하로 인한 균열의 보수 및 보강에 소요되는 비용은 콘크리트 구조물의 유지비용 증대로 연결되어 균열발생 저감에 대한 연구가 요구되고 있다. 특히, 전력공급용 시설인 전력구의 경우 지하 매설물이므로 보수 및 보강은 경제적으로 큰 부담이 된다. 그러므로 지하매설 전력구의 경우 효과적인 균열 저감 방안이 설계 초기단계부터 요구되어진다. 본 연구는 전력구용 저수축 콘크리트 제조를 위한 수축저감제 개발의 일환으로 수축저감제 사용 콘크리트의 초기 강도 개선을 위해 TEA를 검토하였다. 검토결과, TEA를 수축저감제의 3% 사용할 경우 조기 강도가 크게 개선되었으며, 수축저감 효과도 우수한 것으로 확인되었다. 또한, TEA 3 %에 수축저감제 2.0 % 혼합하여 적용하였을 경우 압축강도 특성 및 건조수축 길이변화 실험결과에서 가장 우수한 것으로 나타나 수축저감제로서의 가능성을 확인하였다. 추후 수축저감제의 범용적인 적용성 검토를 위하여 수축저감제의 사용재료 변화 등에 대한 다양한 재료변수 요인 검토를 통하여 수축저감제의 성능 검토가 필요할 것으로 사료된다.

• 대한토목학회논문집
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• 제26권4A호
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• pp.787-794
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• 2006

고성능 콘크리트는 물-결합재비를 작게 하고, 단위결합재량을 다량으로 사용하므로 콘크리트의 수화열 및 자기수축이 증대되는 경향이 있다. 본 연구에서는 고성능 콘크리트의 수축저감 기술을 구축하는 연구의 일환으로 팽창재와 수축저감제 사용이 고성능 콘크리트의 수축특성에 미치는 영향을 검토하였다. 그 결과, 팽창쟁와 수축저감제는 고성능 콘크리트의 수축을 저감시키는 데 효과가 뛰어나며, 특히 팽창재와 수축저감제를 조합하여 사용할 경우, 각각 단독으로 사용하는 경우보다는 수축 저감 효과가 큰 것으로 확인되었다. 또한 시공성, 강도 및 수축특성을 종합적으로 고려하여 팽창재 5.0%와 수축저감제 1.0%의 조합이 적정배합으로 분석되었다.

• 한국전기전자재료학회논문지
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• 제36권2호
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• pp.151-157
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• 2023

Integrating dielectric materials into LTCC is a convenient method to increase the integration density in electronic circuits. To enable co-firing of the high-k and low-k dielectric LTCC materials in a multi-material hetero-laminate, the shrinkage characteristics of both materials should be similar. Moreover, thermal expansion mismatch between materials during co-firing should be minimized. The alternating stacking of an LTCC with silica filler and that with calcium-zirconate filler was observed to examine the use of the same glass in different LTCCs to minimize the difference in shrinkage and thermal expansion coefficient. For the LTCC of silica filler with a low dielectric constant and that of calcium zirconate filler with a high dielectric constant, the amount of shrinkage was examined through a thermomechanical analysis, and the predicted appropriate fraction of each filler was applied to green sheets by tape casting. The green sheets of different fillers were alternatingly laminated to the thickness of 500 ㎛. As a result of examining the junction, it was observed through SEM that a complete bonding was achieved by constrained sintering in the structure of 'calcium zirconate 50 vol%-silica 30 vol%-calcium zirconate 50 vol%'.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.385-390
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• 2002

Autogenous shrinkage of concrete has been defined as decrease in volume due to hydration cement, not due to other causes such as evaporation, temperature change and external load and so on. For ordinary concretes, autogenous shrinkage is so little compared to the other deformations that it has been dignored. It has recently been proved, however, that autogenous shrinkage considerably increase with decrease in water to cement ratio. And it has been reported that cracking can be caused by autogenous shrinkage, when high- strength concretes were used. In this study, we propose an analytical system to represent autogenous shrinkage in cement paste in order to control crack due to autogenous shrinkage. The system is composed with the hydration model and pore structure model. Contrary to the usual assumption of uniform properties in the hydration progress, the hydration model to refine Tomosawa's represents the situation that inner and outer products are made in cement paste. The pore structure model is based upon the physical phenomenon of ion diffusion in cement paste and chemical phenomenon of hydration in cement particle. The proposed model can predict the pore volume ratio and the pore structure in cement paste under variable environmental conditions satisfactorily The autogenous shrinkage prdiction system with regard to pore structure development and hydration at early ages for different mix-proportions shows a reasonable agreement with the experimental data.