• 한국염색가공학회지
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• 제28권3호
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• pp.189-194
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• 2016

The objectives of this research were to study the effect of salt-shrinkage finishing of silk on shrinkage degree and dyeing property of cochineal, and to investigate the efficacy of obtained results for imparting surface design effect on silk fabric. Ultimately it was aimed to suggest a technical process for developing natural dyed silk products with diverse design. Premordanted silk fabric was treated with $Ca(NO_3)_2$ solution(gravity: 1.45) at $90^{\circ}C$ for 1 min, washed, dried for further evaluation. The shrinkage of salt-treated fabric was calculated. The effects of salt treatment on the dye uptake of cochineal and colorfastness were investigated. The degrees of shrinkage were 10% and 3% for warp and weft, respectively. The salt treatment resulted in improving dye uptake of cochineal slightly. In addition, it improved colorfastness to washing and light. On the basis of the results, a technical process composed of premordanting, salt treatment and natural dyeing was suggested and using the process, two examples of textile design were presented. It can be concluded to impart various three dimensional surface design effect on silk fabric by applying salt-shrinkage finishing with combination of natural dyeing and mordanting.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.431-436
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• 2002

In this paper, to seek a solution of reducing autogenous shrinkage three types of bar restricted concrete specimens which have similar compressive strength were tested. The three type of concrete were plain concrete-P25 type, $10^{\circ}C$ fly-ash replaced concrete-F10 type, and $1^{\circ}C$ expansion admixture replaced concrete-SP1 type, and with the test result an experimental study was conducted to gain the tensile stress of concrete. From the result of P25, SP1, F10 tests, it was found that by the age of 14 the ratios of tensile stress to tensile strength of three specimens are $75^{\circ}C$, $47^{\circ}C$, $52^{\circ}C$ respectively. so we came to a conclusion that the SP1-type concrete has better capacity to reduce autogenous shrinkage than F10-type concrete at similar compressive strength condition.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.332-335
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• 2004

Polymethyl Methacrylate(PMMA) mortars using EPS solution-based binders are prepared with various unsaturated polyester resin(UP) contents of binder, and tested for working life. heat exothorm temperature, length change. compressive strength and temperature dependence of compressive strength. As a result, the working life of PMMA mortar is lengthened with raising UP content of binder. Length change of the mortar was condensed from expansion to shrinkage with increasing UP content, and non shrinkage of the mortar is obtained at about UP content of $2.5\%$. The compressive strength of the mortar is increased with an increase in the UP content and reach maximum at UP content of $5\%$. However thermal resistance improvement of the mortar by increasing UP content was not recognized. UP resin was recommended as an effective agent for shrinkage control and strength development of PMMA mortar.

• 콘크리트학회논문집
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• 제16권1호
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• pp.54-60
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• 2004

발포폴리스티렌(EPS)의 효율적인 재활용 기술개발의 일환으로서 폐 발포폴리스티렌을 중합성 모노머인 스티렌에 용해한 고분자 용액에 가교제, 개시제, 촉진제 등을 첨가하여 상온 중합성 결합재를 개발하였으며 이를 이용한 폴리스티렌 모르타르를 제조하여 그 중요한 경화특성인 사용가능시간, 건조양생재령에 따른 발열온도 및 길이변화 거동에 미치는 폐 발포폴리스티렌 용액농도 및 TMPTMA 첨가량의 영향에 대해서 검토하였다. EPS용액을 이용한 결합재 및 폴리스티렌 모르타르의 사용가능시간은 EPS용액 농도 및 TMPTMA 첨가율의 증가에 따라서 짧아지며, 또한 폴리스티렌 모르타르의 경화에 따른 길이변화는 EPS용액 농도 및 TMPTMA 첨가율에 크게 영향을 받는데 이를 적절히 조절하여 경화특성을 제어함으로써 저수축 혹은 무수축 폴리스티렌 모르타르의 제조가 가능하다는 것을 검증하고 있다.

• 한국염색가공학회지
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• 제17권4호
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• pp.41-47
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• 2005

Costume heritages of an excavated silk fabrics should be preserved without damage. In order to artificially restore the excavated silk fabrics, alkaline aqueous solution, as a simulated corpse, and two kinds of silk fabrics were used. Two kinds of silk fabrics were treated by aqueous alkaline solution according to strength retention value(100, 80, 60, 40, 20$\%$). The fine structure and physical properties of alkaline treated silk fabrics were investigated with various techniques such as wide-angle X-ray diffraction, tensile test, weight loss, shrinkage, SEM. and yellowness. As the alkaline treatment time increased tensile strength of silk fabrics decreased. However, weight loss and shrinkage slightly increased. The diffraction intensity of $\beta-form$ crystal declined and $\alpha-form$ crystal diffraction intensity disappeared with the treatment.

• Advances in concrete construction
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• 제7권3호
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• pp.175-181
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• 2019

Low-calcium fly ash (LCFA) were used to prepare cement/LCFA specimens in this study. The basic physical properties including water demand, fluidity, setting time, soundness and drying shrinkage of cement/LCFA paste were investigated. The effects of curing time, immersion time and wet-dry cycles in 3% $Na_2SO_4$ solution on the compressive strength and the microstructures of specimens were also discussed. The results show that LCFA increases the water demand, setting time, soundness of cement paste samples. 50% and 60% LCFA replacement ratio decrease the drying shrinkage of hardened cement paste. The compressive strength of plain cement specimens decreases at the later immersion stage in 3% $Na_2SO_4$ solution. The addition of LCFA can decrease this strength reduction of cement specimens. For all specimens with LCFA, the compressive strength increases with increasing immersion time. During the wet-dry cycles, the compressive strength of plain cement specimens decreases with increasing wet-dry cycles. However, the pores in the specimens with 30% and 40% LCFA at early ages could be large enough for the crystal of sodium sulfate, which leads to the compressive strength increase with the increase of wet-dry cycles in 3% $Na_2SO_4$ solution. The microstructures of cement/LCFA specimens are in good agreement with the compressive strength.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.733-736
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• 2008

본 연구에서는 콘크리트의 염해저항성 및 수축을 저감하는 액상형태의 유무기 화합물로 구성된 내구성개선제(HD)를 개발하고, 이를 슬래그를 사용하는 기존 해안 콘크리트 배합에 적용(결합재 중량의 0.6%, 1.2%)하여 콘크리트의 수축 및 염해저항성을 평가하였다. 내구성개선제를 적용한 결과 염해 및 수축저항성은 이를 적용하지 않은 콘크리트(Plain)에 비해 각각 50%, 33% 개선되는 것으로 나타났으며, 이러한 효과는 HD를 0.6% 적용한 해안가 RCD 구조물에 적용한 현장배합을 통해서도 확인할 수 있었다.

• 콘크리트학회논문집
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• 제20권5호
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• pp.549-555
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• 2008

본 연구는 비활성 황토결합재로 시멘트를 대체함으로써 시멘트의 수화 반응 등에 의한 콘크리트 내부 발열과 수축 특성을 연구하였다. 먼저 재료의 분석을 토대로 압축강도, 슬럼프, 공기량을 살펴보았다. 소형시편과 대형시편을 제작하였고, 보통콘크리트 (OPC)와 황토콘크리트 (HBC)의 수화열, 수축을 측정하여 비교 평가하였다. 황토결합재는 압축강도가 $18{\sim}33\;MPa$로 보통강도 콘크리트의 강도를 발현하였고, 유동성도 확보되는 결과를 보였다. 소형시편에서는 HPC는 OPC에 비해 양생시 내부의 최고온도가 약 1/4 정도로 낮게 나타나고 수축 역시 HBC는 OPC에 비하여 감소하였다. 대형시편에서도 HBC는 OPC에 비해 내부온도가 낮게 나타났으며 수축 역시 60일 기점으로 OPC의 상대적으로 매우 낮은 수축률을 보였다. 따라서 비활성 황토 결합재는 일정강도와 유동성을 확보할 수 있는 재료이며 친환경적 재료이다. 수화열과 수축에 있어 내구성능을 확보하는데 긍정적으로 사료된다.

• 한국주조공학회지
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• 제37권5호
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• pp.148-156
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• 2017

The effects of minor additives on the casting properties of AC4A aluminum alloys were investigated. Measurements of the cooling curve and microstructure observations were conducted to analyze the effects of Ti-B and Sr minor elements during the solidification process. A fine grain size and an increase in the crystallization temperature for the ${\alpha}-Al$ solution were evident after the addition of 0.1wt% Al-5%Ti-1%B additive. The modification effect of the eutectic $Mg_2Si$ phase with the addition of 0.05% Al-10%Sr additive was prominent. A fine eutectic $Mg_2Si$ phase and a decrease in the growth temperature of the eutectic $Mg_2Si$ phase were evident. Fluidity, shrinkage and solidification-cracking tests were conducted to evaluate the castability of the alloy. The combined addition of Al-5%Ti-1%B and Al-10%Sr additives showed the maximum filling length owing to the effect of the fine ${\alpha}-Al$ grains. The macro-shrinkage ratio increased, while the micro-shrinkage ratio decreased with the combined addition of Al-5%Ti-1%B and Al-10%Sr additives. The macro-shrinkage ratio was nearly identical, while the micro-shrinkage ratio increased with the addition of the Al-10%Sr additive. The tendency of the occurrence of solidification cracking decreased owing to the effect of the fine ${\alpha}-Al$ grains and the modification of the $Mg_2Si$ phase with the combined addition of Al-5%Ti-1%B and Al-10%Sr additives.

• 한국수정란이식학회지
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• 제25권1호
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• pp.9-14
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• 2010

This study was conducted to find out the effects of artificial shrinkage (AS) on post-thaw development of bovine embryos. The blastocoelic cavity of blastocyst was punctured to remove its fluid contents and then incubated in the holding medium (HM) for 10 min. The punctured and non-punctured (control) blastocysts were equilibrated in vitrification solution 1 (VS1; TCM-199+20% FBS+10% EG) for 5 min and vitrification solution 2 (VS2; TCM199+20% FBS+35% EG+5% PVP+0.5 M Sucrose) for 1 min and vitrified by direct dropping into the liquid nitrogen. Vitrified blastocysts (punctured and control) were thawed and cultured in vitro (12 hr) for studying survival and hatching rates. The levels of shrinkage were measured by the volume of the blastocyst during equilibration in VS1 (at 1, 3 and 5 min of equilibration) and VS2 (at 30 and 60 sec of equilibration) that was considering the volume of non-punctured blastocyst in HM as 100%. The levels of shrinkage were higher in punctured group (62.4, 64.6, 64.3% at 1, 3 and 5 min in VS1; 50.6 and 52.7% at 30 and 60 sec in VS2) than control group (84.8, 86.6, 86.4% at 1, 3 and 5 min in VS1; 72.1 and 68.8% at 30 and 60 sec in VS2), but within each group the levels of shrinkage were similar. The survival (90.9%) and hatching (50.0%) rates of vitrified blastocysts at 12 hr post-thaw were higher in punctured group than that in control group (76.9% and 0.0% respectively). We confirmed that vitrification solutions (VS1 and VS2) have no toxic effect on the survival of blastocysts because the survival rates of blastocysts exposed to VS1 and VS2 for 24 hr were similar between punctured and control groups (94.3 vs. 96.0%; p>0.05). In conclusion, the preliminary data show that AS of blastocyst may improve survival and hatching rate after thawing.