• Progress in Superconductivity and Cryogenics
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• v.9 no.4
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• pp.46-49
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• 2007

This paper describes the sensitive cooling performance change of J-T refrigerator for cryosurgical probe due to its working fluid. The analytical results of using 50 bar nitrous oxide are compared with the case of 300 bar argon. Bio-heat equation is numerically solved to investigate the effect of the probe temperature and the cooling power of the J-T refrigerator. The refrigerator using 50 bar nitrous oxide has larger cooling power above 185 K than the one with 300 bar argon, which enables fast cooling at early stage of cryosurgery, but the biological tissue away from the probe tends to be cooled slowly after the probe reaches its lowest operating temperature. When the repeated freeze-thaw cycle is employed for main tissue destruction mechanism, using high pressure nitrous oxide is more advantageous than argon if the freezing operation is within 2-3 minutes. The probe with high pressure argon is more suitable for the case of longer freeze-thaw cycle with fewer repetitions.

• Food Science of Animal Resources
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• v.31 no.6
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• pp.799-806
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• 2011

This study was conducted to evaluate the effect of the aging period prior to freezing on the meat quality of Hanwoo longissimus dorsi (LD) muscle. Three different combinations of aging and freezing periods (0/90, 20/70, and 40/50) were examined using LD muscle at 24 h postmortem under an identical storage time of 90 d. The pH and lightness slightly increased with increasing aging period. However, there were no significant (p>0.05) differences in redness and yellowness. The solitary freezing treatment (0/90) had the significantly (p<0.05) lowest moisture content. The un-aged treatment had a significantly (p<0.05) higher total loss than the aged treatments due to an increase in thaw drip loss. The aging significantly improved the myofibrillar fragmentation index and shear force of Hanwoo LD muscle (p<0.05). In addition, the aged treatments produced a higher flavor, tenderness, juiciness, and overall acceptability relative to un-aged treatment. However, there was no significant (p>0.05) difference in shear force and sensorial properties between 20 and 40 d aging prior to freezing. Therefore, 20 d aging prior to freezing may be a sufficiently effective strategy to improve the tenderness and sensorial properties of Hanwoo LD muscle.

• International Journal of Highway Engineering
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• v.20 no.3
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• pp.1-9
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• 2018

PURPOSES : In order to evaluate a crack resistance at cold joint, sealing tape was adopted to apply at cold joint instead of typical tack coat material(RSC-4). The sealing tape was made by hot sealing material. The crack resistance as function of environmental and traffic loading was measured with visual observation. METHODS : In this study, the crack resistance was evaluated as function of environmental and traffic loading. The freeze-thaw method was adopted for environmental loading of asphalt pavement. condition. The damage of cold joint under freeze-thaw action is initiated by ice expansion load and accelerated by the interfacial damage between new and old asphalt pavement. The traffic loading was applied with wheel tracking machine on the cold joint area of the asphalt pavement for 3 hours at $25^{\circ}C$. The evaluation of crack resistance was measured with visual observation. The freeze-thaw results shows that the sealing tape was significantly increased the crack resistance based on. RESULTS : To estimate the crack resistance at cold joint area due to the environmental loading, the Freeze-thaw test was conducted by exposing the product to freezing temperature(approximately $-18^{\circ}C$) for 24 hours, and then allowing it to thaw at $60^{\circ}C$ for 24 hours. The tack coat material(RSC-4) was debonded after 21 cycles of the Freeze-thaw test. The first crack was observed after 14 freeze-thaw cycle with RSC-4 material. But, the sealing tape was not debonded after 24 cycle test. Also, the sealing tape shows the better performance of the crack resistance under the traffic loading with wheel track test. The crack was generated the under traffic loading with RSC-4(tack coating), however, the crack was not shown with sealing tape. It indicates that the sealing tape has a strong resistance of tensile stress due to traffic loading. CONCLUSIONS :Based on limited laboratory test result, a performance of crack resistance using the sealing tape is better than that of general tack coat material(RSC-4). It means that the sealing tape is possible to extend a pavement service life because the crack, one of the main pavement distresses, will be delayed.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.261-272
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• 2009

An experimental study of the accelerated weathering was performed to investigate the variations of physicomechanical properties of deteriorated rocks due to freeze-thaw weathering for the Jurassic granite specimens from Wonju, Gangwon-do. Each complete cycle of freeze and thaw was lasted 24 hours, comprising 2 hours saturating in vacuum chamber, 8 hours freezing at -20$\pm1^{\circ}C$ and 14 hours thawing at room temperature. Freeze-thaw cycles were implemented with measuring the index physical properties as well as geometries of microfractures. The seismic velocity was found to decrease with increasing freeze-thaw cycles. On the other hand, absorption tends to increase with freeze-thaw cycles. In the end, it was concluded that variations of the index properties of deteriorated specimen depend on its initial properties and flaws in rock. The size and density of the traces of the microfracture on slab specimen were changed continuously with increasing freeze-thaw weathering. The results obtained in this study show that the box fractal dimension($D_B$) has the strong capability of quantifying the combined effect of size and density of the microfractures.

• Tunnel and Underground Space
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• v.19 no.2
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• pp.146-157
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• 2009

An experimental study of accelerated weathering on mudstone sample specimens from Haman, Gyeongnam was performed to investigate the variations of physico-mechanical properties of deteriorated rocks due to freeze-thaw weathering. Each complete cycle of freeze and thaw lasted 24 hours, comprising 2 hours of saturating in vacuum chamber, 8 hours of freezing at $-16{\pm}1^{\circ}C$ and 14 hours of thawing at room temperature. Total of 55 cycles of freeze-thaw were completed with measuring the index properties as well as geometries of microfractures. The measured specific gravity and P-wave velocity found to decrease with increasing freeze-thaw cycles. On the other hand, absorption ratio and effective porosity were continuously increased with increasing freeze-thaw cycles. It was found that the index properties of deteriorated sample specimen depend on its initial properties and flaws in rock. The size and density of the traces of the microfracture on slab specimen exhibited abrupt changes after 30 cycles of freeze-thaw weathering. The results obtained in this study show that the box fractal dimension($D_B$) given in this paper has the strong capability of quantifying the size and density of the microfracture.

• Journal of Embryo Transfer
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• v.17 no.2
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• pp.137-143
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• 2002

This study was conducted to evaluate the effect of sugar kinds and combination of various sugars, and straw size and pre-freezing time on motility of post-thaw spermatozoa in canine. In general, the extender was supplemented with fructose or glucose for semen freezing. The extender used in .this study was Tris-citric acid extender (Tris-buffer) supplemented with 20％ Egg-yolk, 8％ glycerol, 1％ Equex STM paste, and 70 mM sugars such as monosaccharide (fructose and xylose) and disaccharide(trehalose). To evaluate of sugar combination, the sugars supplemented in Tris-buffer. were combined such as control (fructose, xylose, trehalose), two combinations (Fru＋Tre, Fru＋Xy1, Tre＋Xy1) and three combinations (Fru＋Tre＋Xy1). The motility after CASA analysis in Fru＋Tre＋Xy1 was higher than those in fructose, trehalose, xylose, Fru＋Tre, Fru＋Xy1, Tre＋Xy1 (69 vs. 58, 61, 50, 65, 20, 54). However, the progressive motility after CASA analysis in Fru＋Tre group was higher than those in fructose, trehalose, xylose, Fru＋Xy1, Tre＋Xy1, Fru＋Tre＋Xy1 (59％ vs. 47, 55, 42, 13, 49, 44％). The survival rate of post-thaw spermatozoa in 0.25 $m\ell$ straw for 10 min pre-freezing was significantly higher than those in 0.25 $m\ell$ straw for 10 min, 0.25 and 0.5 $m\ell$ for 5 min (80＋0.0 vs. 65＋7, 68＋16, 58＋8％; P＜0.05). The results indicated that the progressive motility of post-thaw spermatozoa in 70 mM Fru ＋Tre (two combination) following CASA analysis and 0.25 ml straw for 10 min pre-freezing time could be better for freezing of semen in canine.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.169-170
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• 2017

In this study, the adequacy evaluation of limestone for exterior use is presented. Major flaws of limestone for exterior use are reviewed. In addition, freezing-thawing test of the limestone specimens were performed. As a result, the limestone specimens was damaged by the freezing and thawing action for 300 cycle.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.241-244
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• 1999

This study is represented the strength and freeing-thawing properties of recycled aggregate concrete mixed fly ash by experiment. The experimental variables are the substitution ratio of recycled aggregate and the mixing ratio of fly-ash. For each specimens, there were tested compressive strength and freeze-thaw resistance. It is able to find from the experimental result that the recycled aggregate concrete has good properties as general concrete on the compressive strength and the durability.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.456-461
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• 1997

The purpose of this experimental study are to produce a durable concrete and to investigate the various factors that can deteriorate the concrete when freezing and thawing activity. Among the various factors that can influence the frost resistance of concrete, this study examined mainly the relationship of the frost resistance with the water-cement ratio, admixture and admixture replacement ratio and propose the available water-cement ratio, admixture and admixture replacement ratio.

• Journal of Veterinary Clinics
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• v.36 no.5
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• pp.259-265
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• 2019

This study was designed to investigate the effects of alpha-glucosyl rutin (G-rutin) and its comparative effects with other antioxidants (glutathione: GSH, catalase: CATA and beta-mercaptoethanol : ${\beta}ME$) on dog sperm freezing. In the first experiment (E1), the spermatozoa were diluted in freezing extender supplemented with 0 (control), 0.001, 0.01, or 0.1% G-rutin and frozen using liquid nitrogen ($LN_2$). The progressive motility, reactive oxygen species (ROS) level and apoptosis of spermatozoa were assessed after sperm thawing at $37^{\circ}C$ for 25 sec. In the second experiment (E2), 0.1% G-rutin group was compared with 10 mM ${\beta}-ME$, $5{\mu}M$ GSH and $50{\mu}M$ CATA groups by assaying progressive motility, viability and gene expression of Bcl-2 and SMCP after sperm freezing and thawing. In E1, 0.1% G-rutin group showed higher (P < 0.05) post-thaw progressive motility and lower (P < 0.05) ROS levels. In E2, the expressions of SMCP in G-rutin group were higher (P < 0.05) than in CATA group while Bcl-2 expression of G-rutin group was higher (P < 0.05) than ${\beta}-ME$ and CATA groups. However, there were no significant differences in progressive motility and viability. Therefore, we suggest that G-rutin can be used as a potentially antioxidative supplement in dog sperm freezing extender on the basis of gene expression related to motility and apoptosis as well as ROS level.