• 한국건설순환자원학회논문집
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• 제6권4호
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• pp.331-335
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• 2018

이 연구에서는 건조 모르타르에 사용되는 천연 골재의 대체재로 CFBC 인공 잔골재의 활용가능여부를 확인하고자 건조 모르타르의 플로우와 압축강도를 포함한 기본적인 성능시험과 건조모르타르에서 제품의 품질을 규정하는 데 중요한 성능인 건조수축 성능을 평가하였다. 이를 위하여 천연 골재만 사용한 시험체, 천연 골재에 개질 CaO 팽창재를 혼입한 시험체, CFBC 인공잔골재에 개질 CaO 팽창재를 혼입한 시험체, 마지막으로 CFBC 인공 잔골재만 사용한 시험체를 4종을 제작하여 각 시험체별 길이변화량을 측정하였다. 건조수축 성능 평가결과 재령 20일 기준 천연 규사에 개질 CaO 팽창재를 사용한 시험체의 건조수축 성능이 변형률 $250{\times}10^{-6}$으로 가장 높게 나타났다. 한편, CFBC 인공 잔골재에 개질 CaO 팽창재를 혼입한 시험체는 수축량이 $410{\times}10^{-6}$을 나타내었으며 천연 잔골재를 사용한 건조 모르타르의 건조 수축량은 $450{\times}10^{-6}$으로 개질 CaO 팽창재를 활용할 경우에는 천연 골재를 사용한 건조 모르타르의 건조수축 성능과 동등 이상의 성능을 발휘하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.17-20
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• 2005

In this study, the properties of autogenous shrinkage stress and dry shrinkage stress for high strength concrete using Type I and Type IV cement were discussed. According to experimental results, autogenous shrinkage stress of SN30(the high strength concrete using type I cement) shows values higher than SL30(the high strength concrete using type IVcement). It is observed that the total shrinkage stress of SN30 is higher than that of SL30, because the ratio of autogenous shrinkage stress of the total shrinkage stress is relatively large. Therefore, SL30 is more effective to control or minimize the cracking of the high strength concrete, compared with SN30.

• Journal of the Korean Wood Science and Technology
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• 제37권3호
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• pp.231-238
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• 2009

우리나라에서 전통주택(한옥) 및 목조건축 문화재의 구조부재로 많이 이용되는 소나무는 천연건조가 일반적이어서 건조에 많은 시간이 소요되고 건조가 불충분하면 수축에 의한 갈라짐 및 변형 등의 결함을 일으킬 수 있다. 소나무 소시험편과 대단면 시험편을 제작하여 함수율상태에 따른 수축률변화를 검토하였다. 특정 함수율 상태에서의 체적수축률을 예측할 경우, 생재상태에서 기건상태, 기건상태에서 전건상태까지의 구간으로 나누어 적용하는 것이 정밀도가 높았다. 변재의 체적수축률은 단면크기에는 상관성이 없으며, 심재는 단면이 커질수록 체적수축률이 감소하는 것으로 나타났다.

• Computers and Concrete
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• 제19권5호
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• pp.443-449
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• 2017

Taking high geothermal tunnels as background, the deformation of concrete for shotcrete use was studied by simulating hot-humid and hot-dry environments in a laboratory. The research is made up by two parts, one is the influence of two kinds of high geothermal environments on the deformation of shotcrete, and the other is the shrinkage inhibited effect of fiber materials (steel fibers, polypropylene fibers, and the mixture of both) on the concrete in hot-dry environments. The research results show that: (1) in hot and humid environments, wet expansion and thermal expansion happened on concrete, but the deformation is smooth throughout the whole curing age. (2) In hot and dry environments, the concrete suffers from shrinkage. The deformation obeys linear relationship with the natural logarithm of curing age in the first 28 days, and it becomes stable after the $28^{th}$ day. (3) The shrinkage of concrete in a hot and dry environment can be inhibited by adding fiber materials especially steel fibers, and it also obeys linear relationship with the natural logarithm of curing age before it becomes stable. However, compared with no-fiber condition, it takes 14 days, half of 28 days, to make the shrinkage become stable, and the shrinkage ratio of concrete at 180-day age decreases by 63.2% as well. (4) According to submicroscopic and microscopic analysis, there is great bond strength at the interface between steel fiber and concrete. The fiber meshes are formed in concrete by disorderly distributed fibers, which not only can effectively restrain the shrinkage, but also prevent the micro and macro cracks from extending.

• 한국건축시공학회지
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• 제4권4호
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• pp.71-77
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• 2004

Drying Shrinkage has much complexity as it has relations with both internal elements of concrete and external factors. Therefore, experiments on Concrete Drying Shrinkage are carried out in this study under simplified circumstances applying temperature & Humidity test chamber which enables constant temperature and humidity. Comparative analyses have been made respectively according to the consequences aiming at modelling for prediction of Concrete Drying Shrinkage and making out measures to reduce it. Strain Rate of Drying Shrinkage of concrete under the condition of dry air appears to rise by about 20%-30% in proportion as the temperature rises $5^{\circ}C$ when the humidity was held below 10% compared under the condition of dry temperature & Humidity test chamber. Strain Rate of Drying Shrinkage in pit sand concrete increased 20% higher than measured when in river sand under the condition of 90-day material age. A general formula with two variables is derived as follow ${\varepsilon}={\alpha}_1＋{\beta}_1x_1＋{\beta}_2x_2＋{\beta}_3x_1^2＋{\beta}_5x_2^2$. and also graphed in 3 dimensions, enabling to apply to actual design and predict Strain Rate of Drying Shrinkage in concrete. The results of prediction of Rate of Drying Shrinkage by Response Surface Analysis are as follows. The coefficient of correlation of Drying Shrinkage in Concrete was over 90%.

• Fibers and Polymers
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• 제5권1호
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• pp.19-24
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• 2004

PET yarns textured at different texturing conditions were treated with superheated steam or dry heat at different temperatures for different times. The effects of the treatment conditions on the thermomechanical and structural changes of the yarn were examined by shrinkage, X-ray diffraction and birefringence measurements. With increase in superheated steam temperature, the crystalline orientation factor and birefringence decreased, whereas crystal size increased. Dry heat treatment had a smaller effect on shrinkage and structural properties in comparison with superheated steam treatment. The additional shrinkage after texturing process was investigated. The effect of heat-setting in both media was more significant at $200^{\circ}C$. The time dependence of the properties was not linear.

• 한국염색가공학회지
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• 제34권3호
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• pp.146-156
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• 2022

In this study, the dyeing properties of double knit fabric composed of PET/PTT bi-component fiber and quick dry fiber were examined with disperse dyes. In addition, the shrinkage characteristics were investigated during the dyeing process. The K/S values and shrinkage rate of PET/PTT bi-component fiber were higher than those of PET/co-PET bi-component fiber and quick dry fiber. In the dye bath, dye migration of exhausted on PET/PTT bi-component fiber to quick dry fiber was found at high dyeing temperature. It was not found that there was a significant difference in K/S value on dyeing temperature between 115℃ and 130℃. But the slight color difference of two sides of a double knit fabric was found.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.216-217
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• 2017

Slag cement or ternary blended cement is mainly used for non-structural lean concrete for the purpose of foundation work or protection of the waterproof layer on the roof of buildings. However, such non-structural lean concrete has a lot of drying shrinkage cracks, which makes it difficult to maintain the quality of the structure. Therefore, in this study, the compressive strength and the drying shrinkage of ternary blended cement(blended of portland cement, blast furnace slag, fly ash from combined heat and power Plant) for non-structural lean concrete were examined. As a result, it was confirmed that this non-structural lean concrete reduced drying shrinkage compared to the conventional ternary blended cement using fly ash from power plant.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.199-200
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• 2021

In the study, creep and dry shrinkage characteristics were evaluated to determine the material properties necessary for structural analysis such as column shortening and differential drying shrinkage. All the experiments were conducted in an constant temperature and humidity room. The mechanical properties as well as the specific creep and ultimate dry shrinkage values were derived. In addition the characteristics of the physical value of the high-strength fiber reinforced concrete were considered.

• 한국의류학회지
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• 제4권1_2호
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• pp.25-33
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• 1980

The studies on shrinkage and characteristics of the weft knitted fabrics were investigated under the various dry and wet treating conditions. Various relaxation values were found out according to treating conditions. The characteristics of knitted fabrics such as shrinkage rate, thickness, spirality, elongation and recovery were also measured. The used knitting yams were OE (open-end) cotton and POY (pre-oriented yarn)-DTY (draw textured yam) polyester. The conclusions obtained in this study are as follows. 1. In case of dry relaxation little change of Ks values was seen with increasing time after 48 hours. So it was found that relaxation shrinkage of dry relaxation reached its maximal state in about 48 hours. 2. In case of wet relaxation, higher Ks values were observed, in comparision with those of dry one and higher shrinkage rates were also observed. But when experimental temperature was constant, sudden marked increases in Ks values and shrinkage rates appeared through the initial 4 hours, and after that time little change was seen in them. 3. As Ks value increases, thickness also increased. But thickness showed to some degree stability around Ks value 23. 4. As Ks value increases, spirality values also increased gradually. But little change of spirality values was observed above a certain Ks values (cotton 22.5, polyester 21.5). 5. As Ks value increases, the elongation decreased under a certain load, and the recovery was random.