• 콘크리트학회논문집
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• 제15권3호
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• pp.409-416
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• 2003

본 연구에서는 재유화형 분말수지를 혼입한 초속경 폴리머 시멘트 모르타르의 공기량, 응결시간, 건조수축 및 강도특성에 미치는 분말소포제 첨가율 및 분말 수축저감제 첨가량의 영향에 대하여 검토하였다. 그 결과, 재유화형 분말수지를 혼입한 초속경 폴리머 시멘트 모르타르의 공기량은 분말소포제 첨가율 및 폴리머-시멘트비의 증가에 따라 감소하는 경향을 보였다. 재유화형 분말수지를 혼입한 초속경 폴리머 시멘트 모르타르의 응결시간은 분말소포제 첨가율에 관계없이 폴리머-시멘트비의 증가에 따라 늦어지는 경향을 보였다. 재유화형 분말수지를 혼입한 초속경 폴리머 시멘트 모르타르의 건조수축은 분말소포제 첨가율에 관계없이 폴리머-시멘트비 및 분말 수축저감제 첨가율의 증가에 따라 감소하는 경향을 보였다.또한 분말소포제 첨가율 및 분말수축저감제 첨가율에 관계없이 재유화형 분말수지를 혼입한 초속경 폴리머 시멘트 모르타르의 휨 및 인장강도는 폴리머-시멘트비의 증가에 따라 증가하는 경향을 보였으나, 압축강도는 감소하는 경향을 보였다.

• 콘크리트학회논문집
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• 제12권3호
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• pp.3-10
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• 2000

In this study, we compared a plain mortar with the CAS-system shrinkage compensation mortar for Ondol that is Korean traditional heating system. The Ondol mortar is necessary to have properties as non-crack, fine flatness and stability for thermal changes. especially, mortar'crack prevention is to be most important property in Ondol mortar. To develope the stable material on the crack-prevention, we used to calcium-sulfo-aluminate(CSA)system in shrinkage compensation mortar. And so, we confirmed the effects of calcium-sulfo-aluminate(CSA) system for mortar's physical properties such as setting time, compressive strength and expansion ratio for crack prevention. The initial and final setting time of the CSA mortar is faster than plain mortar about 2hours. And, Compressive strength increased about 20% that plain mortar. The crack length per unit area, plain mortar is 0.426∼0.481m/m2. The Results of apartment construction field test, the shrinkage compensation mortar is excellent about the crack-reduce effect.

• 한국기계가공학회지
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• 제3권3호
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• pp.46-51
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• 2004

Nowadays, plastic industry has needed to produce parts that require high precision and quality. To make a high precision and quality part, before injection molding, plastic material in investigated about their properties such as shrinkage, warpage, etc. In this study, experiments were conducted with PP(polypiopylene) to figure out shrinkage behavior according to three type aspect ratio of samples. The injection speed that affects on shear late, molecular orientation within plastic part was determined as main variable of experiment. As a result of experimental study, part shrinkage had a tendency to be decreased by increasing injection speed and aspect ratio of samples.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
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• pp.69-72
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• 2009

This study reviewed the reduction effect of autogenous shrinkage of high strength mortar by plant edible oils based on existing studies, in an effort to find the method of reducing autogenous shrinkage of high strength concrete. To summarize the results, first as characteristics of fresh mortar, substitution of plant edible oil showed slight reduction in liquidity. Compressive strength was reduce at age of 28 days compared to plain mix regardless of type and substitution ratio. Ratio of change in the length of autogenous shrinkage of high strength mortar by plant oils was found to reduce compared to the plain, and the reduction effect was most satisfactorγ in bean oil.

• Communications for Statistical Applications and Methods
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• 제30권3호
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• pp.311-330
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• 2023

The present work describes simulation studies to compare the performances in terms of averaged mean squared error of bayesian wavelet shrinkage methods in estimating component curves from aggregated functional data. Five bayesian methods available in the literature were considered to be compared in the studies: The shrinkage rule under logistic prior, shrinkage rule under beta prior, large posterior mode (LPM) method, amplitude-scale invariant Bayes estimator (ABE) and Bayesian adaptive multiresolution smoother (BAMS). The so called Donoho-Johnstone test functions, logit and SpaHet functions were considered as component functions and the scenarios were defined according to different values of sample size and signal to noise ratio in the datasets. It was observed that the signal to noise ratio of the data had impact on the performances of the methods. An application of the methodology and the results to the tecator dataset is also done.

• 한국염색가공학회지
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• 제12권2호
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• pp.103-110
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• 2000

To examine the physical properties of POY through the microstructure control, the crystal structure such as the crystallinity, the crystallite size, the orientation, the shrinkage, the tensile properties, and the thermal stress of POY(80/48, SD) were examined at different draw ratios and annealing temperatures. From the examination following conclusions were obtained : 1. The crystallinity was more effected by the heat setting temperature than by the draw ratio. The increasing rate was greatest at the heat setting temperature range of $170~190^\circ{C}$. 2. The crystallite size perpendicular to the fiber axis was more effected by the annealing temperature at lower draw ratios. On the other hand, the crystal and amorphous orientations were more effected by the heat setting at higher draw ratios. 3. The boiling shrinkage did not change significantly, but the total shrinkage showed 13% at the draw ratio 1.9 and the heat setting temperature $170^\circ{C}$. 4. The maximum thermal stress increased with increasing the draw ratio and decreasing the heat setting temperature in the temperature range of $170~210^\circ{C}$. At the draw ratio 1.9 and the heat setting temperature $170^\circ{C}$, the maximum thermal stress found was 1.1gf/d. 5. In the heat setting temperature above $170^\circ{C}$ after the drawing, the crystallinity, the crystallite size, the orientation, and the strength increased with increasing temperature, but the shrinkage and the maximum thermal stress decreased with increasing temperature.

• 산업기술연구
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• 제22권A호
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• pp.193-200
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• 2002

Drying shrinkage cracking which may be caused by the relatively large specific surface IS a matter of grave concern for latex modified concrete(LMC) overlay and rapid-setting cement latex modified concrete(RSLMC) overlay. LMC and RSLMC were studied for field applications very actively in terms of strength and durability in Korea. However, there were no considerations in drying shrinkage. Therefore, the purpose of this dissertation was to study the drying shrinkage properties of LMC and RSLMC with the main experimental variables such as cement types(ordinary portland cement, rapid setting cement), water-cement ratios and curing days at a same controlled environment of 60% of relative humidity and $20^{\circ}C$ of temperature The drying shrinkage for specimens was measured with a digital dial gauge of Demec. The test results showed that the drying shrinkage of LMC and RSLMC were considerably lower with low water-cement ratio, respectively This might be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic, and colloidal properties of the latexes resulting in reduced water evaporation.

• 콘크리트학회논문집
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• 제15권6호
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• pp.785-793
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• 2003

본 연구에서는 플라이애쉬, 고로슬래그 미분말 및 실리카 퓸 등 광물질 혼화재를 사용하는 고성능 콘크리트에서 자기 및 건조수축을 저감하기 위한 방안으로 팽창재, 수축저감제 및 팽창재와 수축저감제를 병용 사용하는 것에 대하여 분석하였다. 실험결과, 팽창재 및 수축저감제 혼입은 적정 혼입률 범위내에서 유동성 및 공기량에 큰 영향을 미치지 않는 것으로 분석되었으며 재령 91, 180일의 강도발현도 양호한 것으로 나타났다. 또한, 팽창재 5%, 10%에서는 플레인 콘크리트와 비교하여 자기수축을 32∼68%, 건조수축은 25∼49% 감소하는 것으로 나타났고, 수축저감제 혼입률 0.5%, 1.0%에서는 플레인 콘크리트와 비교하여 자기수축은 18∼34% 및 건조수축은 16∼26% 저감하는 것으로 나타났다. 특히, 팽창재와 수축저감제를 병용한 경우의 EA-SR배합에서는 수축저감의 효과가 가장 우수한 것으로 나타났다. 따라서 플라이애쉬, 고로슬래그 미분말 및 실리카 퓸 등 광물질 혼화재를 사용한 고성능 콘크리트의 수축을 저감시키기 위해서는 팽창재와 수축저감제를 병용 사용하는 것이 효과적인 것으로 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.101-106
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• 2003

This study is to capture autogenous shrinkage in reinforced concrete. The experiment was carried out on total 13 beams. The experiment parameters are a method of curing and reinforcement ratio. Autogenous shrinkage in reinforced concrete beam was experimentally measured. Also, the distribution of autogenous shrinkage and self stress on cross section in reinforced concrete beams were calculated. The experimental results showed that autogenous shrinkage of high strength concrete were significantly higher than that of nomal strength concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.592-595
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• 2004

This Study discusses the properties of drying shrinkage of concrete slab with W/B, water content, fiber and anti-shrinkage agent. According to results, drying shrinkage is reduced with decrease of water content and W/B. Also, compared with plain concrete, drying shrinkage is reduced by using of fiber, anti-shrinkage agent and adding ratio of anti - shrinkage agent. Therefore, in the range of workability if water content and W/B are reduced and using of fiber and anti-shrinkage agent are performed properly, crack by drying shrinkage can be prevented effectively.