• Journal of the Korea Institute of Building Construction
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• v.17 no.5
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• pp.419-427
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• 2017

In order to examine the possibility of practical use of aluminate cement concrete at low-temperature environment with insulation method, an experimental studies on flowability, setting time, freezing temperature, size variation and compressive strength of the mortar at low-temperature were conducted. Compressive strength was increased in use of CSA, aluminate cement with gypsum. Workability and physical properties were improved by using aluminate cement and gypsum. In addition, freezing resistance and physical properties were improved by applying the insulation curing method. Especially, when alumina cement and gypsum were used together, the insulation curing method was more effective in improving the compressive strength.

• Journal of the Korean GEO-environmental Society
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• v.13 no.2
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• pp.5-17
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• 2012

The amount of snow due to global warming and climate change has recently increased. The effective management of snow removal materials will be required. First, on the basis of domestic winter temperature, it is not necessary to get a baseline to less than the freezing point of $-52^{\circ}C$ for the calcium chloride($CaCl_2$) of 30%.. In terms of cost comparison between calcium chloride($CaCl_2$) and sodium chloride($NaCl$), the calcium chloride($CaCl_2$) is 2 to 3 times more expensive, and the supply of the calcium chloride($CaCl_2$) is not produced in domestic country and is in the conditions that have to imports all needed. Accordingly, the effective use scheme of snow removal materials should be considered to multifaceted ways. Thus, the objective of this study is to develop effective method and to replace from calcium choride($CaCl_2$) to sodium chloride($NaCl$) solution in the current snow removal operating system that uses a pre-wetted salt spreading method. The effective method that equals to the quality of the existing snow removal materials was developed in this study through performance tests for deicing chemicals, corrosion test of steel and freezing and thawing tests of concrete.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.3
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• pp.247-252
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• 2019

We observed MMPs expression in all sperm groups, with pro-MMP showing lower expression than active MMPs. According to the results from each freezing extender, the sperm membrane integrity (HOST: Hypoosmotic Swelling Test) analysis in TCGGD (Tris 250 mM, Citric acid 88 mM, Glucose 47 mM, Glycerol 3%, Dimethylsulpoxide 3.5 M) is 59.8 ± 0.7, TCGSD (Tris 250 mM, Citric acid 88 mM, Glucose 47 mM, Sucrose 0.1 M, Dimethylsulpoxide 3.5 M) is 59.3 ± 0.5 were significantly higher (p < 0.05) among the experimental groups. And MMPs analysis result, we observed MMPs expression in all sperm groups, with pro-MMP showing lower expression than active MMPs. The expression of active MMP-2 was the highest in sperms frozen in TCGSD and TCGD (Tris 250 mM, Citric acid 88 mM, Glucose 47 mM, Dimethylsulpoxide 3.5 M), Meanwhile, sperms from the TCGGD and TCGED (Tris 250 mM, Citric acid 88 mM, Glucose 47 mM, Ethylene glycol 3%, Dimethylsulpoxide 3.5 M) group showed lower level of active MMP-2 expression. Together, these results indicate that adding glycerol or sucrose to the sperm freezing buffer would not only suppress MMPs expression but also minimize DNA fragmentation, providing a mean to improve the success rate in the in vitro manipulation of rabbit sperms. Therefore, these results suggest that TCGGD or TCGSD extender method for freezing-thawing of rabbit sperm increased the viability after thawing.

• Proceedings of the KSAR Conference
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• 2001.03a
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• pp.6-6
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• 2001

Oocyte freezing has become a prevalent source for related reproductive technologies. This study was carried out to evaluate viability of post-thawed bovine oocyte injected DTT-treated sperm following by two different activation stimuli (Group 1, 5 M ionomycin, 5 min ＋ CR1aa, 3 h . 1.9 mM dimetylaminopurine (DMP), 3 h; group 2, ionomycin ＋ 10 $\mu\textrm{g}$/$m\ell$ cycloheximide(CHX), 5h). The techniques of ultra-rapid freezing used in this study were essentially similar to those of described by Vajta et al (Theriogenology 1999; 52:939-948), Denuded oocytes at 22 h of culture were exposed to cryoprotectant (3.2 M Ethylene glycol, 2.36 M DMSO, 0.6 M sucrose), and followed by freezing in electron microscopic grid. After thawing the oocytes were transferred back into the drop of maturation medium and cultured for additional 2 h before being subjected to ICSI. All eggs were then cultured in CRlaa medium, and transferred into M199+10% FCS on day 4. The culture was maintained until day 9. In Experiment 1, frozen-ICSI eggs were compared on development into blastocyst to those of unfrozen and IVF control. Those eggs were activated with the method of group 2. A higher proportion of unfrozen-ICSI and IVF eggs developed into cleavage and blastocysts than of frozen-ICSI eggs (65% and 13%; 71% and 23% vs. 39% and 8%; P<0.05). In Experiment 2, development and ploidy of embryos made from group 1 were compared to those from group 2. Between groups there did not differ on the rates of development, however, chromosomal abnormality in group 1 was significantly higher than in group 2 (49% vs. 30%; P<0.05). The present result suggests that frozen bovine oocytes can be used for ICSI.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.447-450
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• 1997

A new technique for the preparation of porous vascular prostheses was investigated. Polyurethane solution (10 to 14wt%) was injected into a mold. After freezing at low temperature $(0^{\circ}C\sim-40^{\circ}C)$, solvent was dissolved out with water at $0^{\circ}C$ to form porous tubes. The average pore size $(<10{\mu}m)$and pore occupation (10% to 51%) were easily changed by changing polyurethane concentration, freezing temperature, and freezing methods. This technique can give a proper pore size $(30\sim60{\mu}m)$ for tissue ingrowth, and suitable compliances for matching with arteries and veins. This method might give a desired compliant graft for artificial implantation with the presently valid medical polymers.

• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.293-301
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• 2016

Objective: The purpose of this study was to analyze the effects of freezing of gait and visual information on the static postural control ability in patients with Parkinson's Disease (PD) during the bipedal stance with feet together. Method: This study included a total of 36 patients with PD; the freezer group included 17 PD patients (age: $69.3{\pm}6.2yrs$, height: $159.6{\pm}9.0cm$, weight: $63.4{\pm}9.78kg$) and the nonfreezer group included 19 PD patients (age: $71.4{\pm}5.6yrs$, height: $155.8{\pm}7.1cm$, weight: $57.7{\pm}8.6kg$). Static postural control ability was analyzed using variables of center of pressure (COP) and dividing by mediolateral, anteroposterior, and integration factors during a bipedal stance with the eyes open and closed. Results: Freezers and nonfreezers showed increases in anteroposterior velocity, mediolateral velocity, averaged velocity, and mediolateral 95% edge frequency when visual information was blocked. Additionally, freezers had greater anteroposterior range, 95% confidence ellipse area, and COP anteroposterior mean position than nonfreezers. Conclusion: Freezers and nonfreezers showed a reduction in static postural control ability when visual information was blocked. Additionally, the results of this study found a significant difference in static postural control ability between freezers and nonfreezers with PD. In particular, anteroposterior range, 95% confidence ellipse area, and COP anteroposterior mean position might be used to distinguish between freezers and nonfreezers with PD.

• Korean Journal of Food Science and Technology
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• v.20 no.4
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• pp.536-540
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• 1988

Effects of blanching time, chemical dipping, freezing method and storage period on texture, color and yield of frozen whole and sliced mushrooms were investigated, and the results are summarized as follows; Frozen whole mushrooms blanched for 5min. had markedly tougher texture than mushrooms blanched for 1 or 2 minutes. As the storage time of frozen mushrooms increased from 3 to 6 months, shear press values increased very significantly. The texture of Freon frozen and plate frozen mushrooms was similar after 3 months storage. Blanching time did not affect texture of frozen sliced mushrooms significantly, but storage time did. The results of sensory evaluation for texture were in good agreement with shear press values. Chemical dipping methods were effective in maintaining desirable color of frozen whole and sliced mushrooms stored for 3 months. The yield of frozen whole mushrooms was significantly increased by shortening blanching time in combination with chemical dipping. Sliced mushrooms required at least 2 min. blanching, to avoid excessive breakage in mechanical slicing operation, for better yield.

• Journal of Embryo Transfer
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• v.24 no.4
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• pp.275-279
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• 2009

The beneficial effect of glycerol as a cryoprotectant, especially for sperm cryopreservation, has been shown in many studies. However, glycerol is toxic to living cells, and boar sperm in particular show greater sensitivity to glycerol than sperm from other domestic animals. Amides have been studied as alternative cryoprotectants for freezing stallion sperm. Sperm frozen in methylformamide or dimethylformamide as cryoprotectants show similar motility when thawed compared with sperm frozen in glycerol. We evaluated the cryoprotective effects of dimethylformamide on boar sperm freezing. To test the effect of amides, the concentration of boar semen was adjusted to $10^9sperm/mL$, and seminal plasma was removed using Hulsen solution. After centrifugation, the pellet was diluted in modified-Modena B extender. Lactose-egg yolk (LEY) extender was used as the cooling extender. The freezing extender was madeed aaddition of the optimal amount of glycerol and amides to LEY-Glycerol-Orvus ES Paste extender, and this extender was used for the second dilution. Diluted sperm were frozen in liquid nitrogen using the 0.5 mL straw method. Sperm frozen in extender with glycerol as a cderol were compared with those frozen in extender including the different amides. Sperm were tested for motility, viability, the sperm chromatin structure assay, and normal apical ridge after thawing. The percent of motile sperm diluted in glycerol was as high as that in the stallion study (61%). Dimethylformamide showed positive effects on sperm quality and was better than glycerol. Methylformamide provided similar sperm quality as glycerol. Therefore, dimethylformamide is useful for reducing cryoinjury in boar sperm and is expected to be useful as an alternative cryoprotectant.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.175-176
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• 2022

By studying the characteristics of matrix insulated through heat generated through oxidation of iron powder, the basic research results on the possibility of buffering and applicability of Cold weather concrete as a curing method are presented. In order to prevent freezing due to a sharp decrease in temperature in the initial stage of curing, iron powder (Fe), powder activated carbon, which is a small amount of porous carbonaceous adsorbent, and salt (NaCl) as an oxidizing agent are replaced with iron powder admixture. As the curing temperature increases, the strength tends to increase, and when replacing the admixture at the same curing temperature, the strength slightly decreases. This is determined as a result of generating iron oxide through an oxidation reaction of iron powder, activated carbon, and NaCl generating a large amount of pores in the matrix. In addition, the internal temperature tends to increase as the mixing substitution rate increases, and it is judged that the oxidation heat of the iron powder mixture affects the increase of the internal temperature during curing. The higher the replacement rate of the iron powder mixture, the slightly lower the strength, but it is determined that freezing and melting that may occur in the early stage of curing can be prevented due to an increase in the initial internal temperature.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1001-1004
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• 2008

This study reviewed the results of utilization of insulation heat curing method using double layer bubble sheet in slab concrete and mass concrete in cold weather environment. First of all, when double layer bubble sheets are applied, it was shown that slab concrete was protected from early freezing by remaining between 6 and $10^{\circ}C$ even in case outside temperature drops $10^{\circ}C$ below zero until the 2nd day from piling, and in the case of mass concrete, with the maximum temperature difference between the center and surface less than $6^{\circ}C$, crack occurrence index was close to 2 and no hydration heat crack occurred by internal constraint. The insulation heat preservation curing method using the double bubble sheet applied in this field prevented early freezing owing to stable curing temperature management, deterring concrete strength development delay at low temperature, and obtained the needed strength. Also, it was proven that the method is highly effective and economic for cold weather concrete quality maintenance through curing cost reduction like construction period shortening and labor cost reduction, etc by reducing the process of temporary equipment installation and disassembling.