• Journal of the Society of Disaster Information
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• v.6 no.1
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• pp.78-90
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• 2010

Exposure to the outside, the concrete is differential moisture distribution depending on the depth. Such a differential moisture distribution causes the differential drying shrinkage in concrete structures. This thesis is researched to compare the shrinkage of lightweight concrete depending on depth to normal concrete. It is used artificial lightweight aggregate which has 20% of pre-absorb value by lightweight concrete. When water-binder ratio is 30%, average shrinkage of lightweight concrete section decreased than normal concrete, but differential shrinkage of lightweight concrete section increased. However water-binder ratio is 40% and 50% average shrinkage and differential shrinkage of lightweight concrete section decreased than normal concrete.

• Structural Engineering and Mechanics
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• v.52 no.1
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• pp.97-113
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• 2014

In the present work appropriate concrete material models have been proposed to predict drying shrinkage and specific creep of High-performance concrete (HPC) using Artificial Neural Network (ANN). The ANN models are trained, tested and validated using 106 different experimental measured set of data collected from different literatures. The developed models consist of 12 input parameters which include quantities of ingredients namely ordinary Portland cement, fly ash, silica fume, ground granulated blast-furnace slag, water, and other aggregate to cement ratio, volume to surface area ratio, compressive strength at age of loading, relative humidity, age of drying commencement and age of concrete. The Feed-forward backpropagation networks with Levenberg-Marquardt training function are chosen for proposed ANN models and same implemented on MATLAB platform. The results shows that the proposed ANN models are more rational as well as computationally more efficient to predict time-dependent properties of drying shrinkage and specific creep of HPC with high level accuracy.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.271-272
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• 2010

This thesis is researched to compare the shrinkage of lightweight concrete depending on depth to normal concrete. It is used artificial lightweight aggregate which has 20% of pre-absorb value by lightweight concrete. When water-binder ratio is 30%, average shrinkage of lightweight concrete section decreased than normal concrete, but differential shrinkage of lightweight concrete section increased. However water-binder ratio is 40%, average shrinkage and differential shrinkage of lightweight concrete section decreased than normal concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.331-335
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• 2018

The purpose of this study is to investigate the feasibility of CFBC artificial fine aggregate as a substitute for natural aggregate used in dry mortar. The basic performance of the flow, compressive strength and dry shrinkage of the dry mortar was evaluated. Four types of test dry mortar specimens using natural aggregate without expansion admixture, a specimen with modified CaO expansion admixture and natural aggregate, a specimen with modified CaO expansion admixture and CFBC artificial fine aggregate, and a specimen using CFBC artificial fine aggregate without modified CaO expansion admixture were evaluated respectively. As a result of evaluation of drying shrinkage performance at 20th day of age, the dry shrinkage performance of the specimen using modified CaO expansion admixture was found to be the highest at $250{\times}10^{-6}$. On the other hand, the specimen containing the modified CaO expansion admixture with CFBC artificial aggregate exhibited a shrinkage of $410{\times}10^{-6}$, and the drying shrinkage of specimen using natural fine aggregate without expansion admixture was $450{\times}10^{-6}$. When the modified CaO expansion material was used, and exhibited performance equal to or higher than that of the shrinkage-drying property.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.6
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• pp.1050-1059
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• 2017

Drying processes often cause knitted fabrics to shrink. This study obtains proper drying conditions for in the dryer use that can minimize knitted fabric shrinkage by investigating changes in shrinkage according to drying conditions. The experiment samples were all machine washable plain, mesh, and lacoste knitted fabrics made of 100% cotton. Samples were first washed in a washing machine on a normal cycle. They were then layered on a flat surface in an artificial climate chamber and dried for 24 hours at $20^{\circ}C$ and $40^{\circ}C$, respectively. Shrinkage was measured for 180 minutes at 30 minute intervals after washing. The comparison results of the shrinkage in the washing and drying process indicate that 80.0% and 23.0% shrinkage of plain knitted and lacoste knitted fabrics occurred during the washing process. As the samples dried, the shrinkage of the plain and lacoste knitted fabrics then rapidly increased after approximately 30.0% moisture content. The highest air drying shrinkage occurred over one cycle with insignificant changes in shrinkage after repeated treatments.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.195-198
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• 1999

Fly ash is the most common artificial pozzolan, which is a material precipitated electrostatically from the exhaust gases of coal-fired power stations. Fly ash can be used as the supplementary material as well as the material for high performance concrete and hence, the development of high-volume fly ash concrete is imperative. In this study, the characteristics of drying shrinkage of high volume fly ash concrete is investigated. It is found from test results that as the replaced amount of fly ash in concrete is increased, drying shrinkage of concrete is reduced.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.87-93
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• 2018

The use of high-strength concrete in construction have been increasing steadily. However, high-strength concrete has a low water-binder ratio, and the problems such as cracks due to hydration heat and shrinkage during the hydration process at the early age. Recently, as a method to reduce the shrinkage of concrete, study of internal curing has carried out according to increasing about interest about it. In this study, the effect of compressive strength on the curing condition(drying, moist, water) was investigated by using artificial lightweight aggregate(LWA) in high strength and high volume mortar. As a result of autogenous shrinkage, the effect of shrinkage reduction was enhanced depending on the increasing of LWA replacement. According to the curing condition, the results of compressive strength showed the different trend. The compressive strength has increased on the drying and moisture condition and decreased on the water condition.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.36-39
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• 2003

In this study, we made the high strength light weight concrete which was composed of the garnet minute powder to be the industry by-product in the YoungJoo region and the artificial light weight aggregate which the high temperature(1100℃) plastic process. The characteristic of the autogenous shrinkage had been considered about strength characteristic and the age passage In the following addition: The concrete's each unit quantity was determined 145,160,175㎏f/㎥.w/b and s/a was determined 30%, 43%, 45%. the each garnet's substitution ratio was determined 0, 10%. In this results, the compressive strength appeared greatly as the unit joining discretion grew bigger. The autogenous shrinkage ratio was increased rapidly until 7th day but it was reduced after 7th day regardless of the mixed factor. The autogenous shrinkage ratio which follows the change of the unit quantity and s/a increased together as the unit quantity and the s/a increases.

• Journal of Embryo Transfer
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• v.25 no.1
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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.

• Clinical and Experimental Reproductive Medicine
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• v.32 no.1
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• pp.65-70
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• 2005

본 연구는 이식 후 남은 잉여의 포배기 배아를 두 번의 냉동과 융해 과정을 반복적으로 실시한 후 이식한 결과에 관한 보고이다. 사람 포배기 배아의 동결보존에서 높은 생존율과 성공적인 임신율이 보고되고 있으나 미성숙 난자로부터 발달한 포배기 배아에 두 번의 초급속 냉동 방법을 실시한 후 이식한 보고는 되어 있지 않다. 이에 본 연구에서는 다낭성 난소 증후군 환자에게서 얻은 미성숙 난자로부터 발달한 포배기 배아를 artificial shrinkage 후 초급속 냉동함으로써 생존율을 높이는 방법을 이용하여 재냉동 이식하였을 때 임신에 성공한 증례를 보고하고자 한다. 29세의 환자로부터 채취한 55개의 미성숙 난자들(germinal vesicle stage oocytes)을 체외배양 하여 성숙한 37개의 난자들로부터 30개의 수정란을 얻을 수 있었다. 12개의 배아가 포배기 배아까지 발달하였으며 이 중 3개의 양질의 포배기 배아를 선별하여 이식하였고, 이식을 한 후에 남은 9개의 포배기 배아들은 artificial shrinkage의 과정을 마친 후에 초급속 냉동 방법을 이용하여 동결보존 하였다. 그 중, 4개의 포배기 배아들을 융해한 후 이식을 하지 않고 다시 재냉동을 하여 보관하였고 이 후 재냉동 되었던 4개의 포배기 배아들을 다시 융해 하여 이식을 한 결과 임신이 되어 건강한 남아를 분만하였다. 이로써 미성숙 난자로부터 얻은 포배기 배아가 두 번의 냉동과 융해의 과정을 통해 크게 손상을 입지 않고 생존할 수 있다는 것을 알 수 있었다. 그러므로 융해이식 후 남은 잉여의 포배기 배아를 다시 냉동 보관하여 다음 주기에 이용함으로써 축적된 임신율을 증가시킬 수 있을 것으로 사료된다.