• Development and Reproduction
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• v.21 no.1
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• pp.79-91
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• 2017

The aim of this study was to compare the efficacy of cryopreservation methods for ex situ conservation of spermatozoa from far eastern catfish, Silurus asotus. The spermatozoa activity index (SAI) and hatching rates were higher in spermatozoa stored in Alserver's solution than those of spermatozoa stored in glucose solution. The SAI and hatching rates in all experimental groups gradually decreased with increasing duration of storage. Additionally, the SAI and hatching rates gradually decreased with increasing thawing temperatures at all storage durations (P<0.05). Based on the SAI and hatching rates, our results suggest that the optimal cryopreservation conditions of catfish spermatozoa involve storage in Alserver's solution with 15% ethylene glycol, and thawing at $25^{\circ}C$. Cryopreservation of spermatozoa is a useful and reliable technique for conserving gene resources and for artificial propagation of far eastern catfish.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.5
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• pp.665-671
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• 2010

Muscle fiber characteristics and their relationship to water-holding capacity of longissimus dorsi (ld) muscle were studied in Brahman (BRA) and Charolais (CHA) crossbred bulls fattened under practical farm conditions. Thirty-four BRA and 34 CHA bulls were randomly selected and slaughtered at 500, 550 and 600 kg live weight. Parameters of water-holding capacity such as drip, ageing, thawing, cooking and grilling loss were determined. Muscle fiber characteristics were conducted for muscle fiber type percentage and cross-sectional areas of slow- and fast-twitch fiber types, and correlation coefficients to water-holding capacity parameters were calculated. Results showed that CHA meat had a better water-holding capacity (less ageing, thawing and grilling loss) when compared with BRA, whereas slaughter weights had no significant effects on these parameters. Furthermore, there were no significant differences between genotypes and slaughter weights in muscle fiber type percentage and cross-sectional areas of ld muscle. Slow- and fast-twitch fiber types of all experimental groups averaged 24.4 and 75.6%, respectively. Cross-sectional areas of fast-twitch fibers had almost twice the size of slow-twitch fibers (6,721 and 3,713 ${\mu}m^2$, respectively). The correlation between muscle fiber area and water-holding capacity indicated that muscles with larger fiber areas had a lower drip and ageing loss but a higher cooking and grilling loss.

• International Journal of Highway Engineering
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• v.11 no.3
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• pp.75-83
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• 2009

A need still exists to evaluate the durability performance of cemented gedmaterials in road constructions using various cementing binders due to seasonal changes in fields as well as structural performance. In this paper, durability characteristics of stabilized granular base and subgrade materials, which is widely used in korea, was assessed using a laboratory repeated load resilient-deformation test under various freezing-thawing and wet-drying cyclic conditions. In addition, various resilient modulus models were adopted based on the test results. As a result, the estimated model coefficients agree well with the values from the literatures.

• Korean Journal of Animal Reproduction
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• v.16 no.3
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• pp.217-224
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• 1992

These studies were carried out ot investigate on the transferred embryo development following ultrarapid frozen for 8-cell and morula of in vitro fertilization mouse embryos. The post-thaw embryo survival was evaluated and compared by cell stage of embryos and by equilibration time before ultrarapid freezing. The results obatined were summerized as follows: 1. The effects of equilibration time of 3 vs. 6 minutes before ultrarapid freezing and after thawing on the morphological survival and the viability of 8-cell and morulas embryos were not significant. 2. When the ultrarapid frozen-thawed 32 eight-cell and 33 morula embryos, and 30 fresh blastocysts were transferred to pseudopregnant recipient mice, the number of normal offsprings produced were 9(28.1%), 14(42.4%) and 18(60.0%), respectively. From the above resutls, it was concluded that the optimal conditions of pH osmolality of the media for mouse IVF and embryo culture, and the period of sperm preincubation might be 7.1, 310 mOsm and 120 min., respectively,a nd somewhat high conception rate might be resulted from transfer of frozen embryos of morula stage and fresh embryos of blastocyst stage.

• Journal of Embryo Transfer
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• v.14 no.3
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• pp.163-169
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• 1999

This study was carried out to investigate the effect of co-culture system(bovine oviduct epithelial cells; BOEC) and defined culture system(modified TALP ; mTALP) on the development of IVM-IVF embryos, and survival of in vitro produced blastocysts after freezing and thawing. Occytes from the slaugheterhous ovaries were matured and fertilized using general protocol. The results obtained were as the following: 1. Survival rates of frozen-thawed blastocysts using 10% glycerol as cryoprotectant was higher in day 7 blastocysts than in Day 8 and 9 blastocysts from co-cultrue system, but survival rate of frozen-thawed blastocysts was higher in Day 10 blastocysts than in day 8 and 9 blastocysts from defined culture system. Regardless of their age, survival rate of frozen-thawed blastocysts was significantly higher (p<0.05) in co-culture system than in defined culture system. 2. The cell number of blastocysts was significanlty higher (p<0.05) in Day 7 blasotcysts than in Day 8 and 9 blastocysts from co-cultures, but the cell number of blsstocysts was significantly higher (p<0.05) in Day 10 blastocysts than in Day 8 and 9 blastocysts from defined culture system. Regardless of the culture system, blastocysts with higher cell number showed higher survival rates after freezing and thawing.

• Journal of The Geomorphological Association of Korea
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• v.25 no.1
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• pp.47-65
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• 2018

Frost shattering has traditionally been considered as one of the most effective process in rock weathering. Each slab specimens of five or six rhyolite, basalt and tuff was prepared and put in freeze-thaw cycles and repeated 300 times in the temperature of $-25^{\circ}C$ to $+30^{\circ}C$ and their weathering patterns and products were analyzed by surface observation, particle size, XRD and thin section. As the result, some changes were observed in weathering patterns and weathering products. Rock shattering was more active in waterlogging rather than atmospheric conditions, but there are many differences depending on the type of rock. Rhyolite is hardly weathered by 300 times freeze-thaw cycles and generates the least amount of weathering products. Weathering of Basalt is limited to the surface layer where water can be absorbed, and produces a few amount of platy-shape debris. Tuff are separated by blocky structure which the particles are aggregated along their edges rather than enlarged existing cracks/joins or generated new joints.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.406-413
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• 2001

Up to this day, reinforced spun concrete pipes have been widely used as drain pipes. However, many reinforced spun concrete pipes are exposed to the deteriorated environment such as freezing-thawing damage and chemical attack by the growth of a sulfur-oxidizing bacterium isolated from corroded concrete. The purpose of this study is to evaluate the effects of lining by polymer-modified mortar using polymer dispersions as cement modifier on the development in durability of reinforced spun concrete pipe. The polymer-modified mortars were prepared with various polymer types and polymer-cement ratios, and tested for compressive and flexural strengths, acid, freezing-thawing, and heat resistances. And then, the reinforced spun concrete pipe product lined by polymer-modified mortars was tested for adhesion in tension and surface conditions according to curing temperatures in the field. From the test results, it is apparent that the polymer-modified mortars have good mechanical properties and durability as a lining material. In practice, all polymers can be used as lining the materials for reinforced spun concrete pipe, and types of polymer, and polymer-cement ratio and curing conditions are controlled for a good lining product.

• Journal of Veterinary Clinics
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• v.34 no.2
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• pp.156-160
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• 2017

We investigated the effect of ethylene glycol and antioxidants such as taurine, hypotaurine and trehalose with extenders during cryopreservation of Korean Jeju Black Bull spermatozoa. The cryopreservation of freshly collected spermatozoa was conducted with four different conditions. As a control, spermatozoa were cryopreserved with Tris egg-yolk extenders added 5% ethylene glycol (EG). Taurine (20 mM), hypotaurine (20 mM) and trehalose (20 mM) were individually added into tris egg-yolk extenders with 5% EG. After thawing of frozen spermatozoa with four different conditions, sperm viability, motility, acrosomal integrity, and membrane integrity were investigated. The significant (p < 0.05) improvement of sperm viability showed in all antioxidant treated thawed spermatozoa (taurine; $68.1%{\pm}4.4$, hypotaurine; $69.2%{\pm}6.7$ and trehalose; $68.0%{\pm}4.4$) when compared to control ($63.4%{\pm}5.6$). Neither positive nor detrimental effects of three antioxidants were shown sperm motility after thawing. The results of hypo-osmotic swelling test showed that the membrane integrity of taurine, hypotaurine or trehalose treated thawed spermatozoa ($64.1%{\pm}5.4$, $61.5%{\pm}3.7$ and $59.0%{\pm}4.0$, respectively) had significantly (p < 0.05) higher rate of the swollen sperm compared to control ($53.7%{\pm}9.7$). Hypotaurine treated frozen-thawed spermatozoa had siginificantly higher (p < 0.05) F pattern ratio than taurine, trehalose and control treated frozen-thawed spermatozoa. Trehalose added frozen-thawed spermatozoa had significantly higher (p < 0.05) acrosome reaction pattern ratio than taurine and hypotaurine added frozen-thawd spermatozoa. In this study, we found that antioxidants such taurine, hypotaurine and trehalose treatments during cryopreservation process could reduce damage of spermatozoa of Korean Jeju Black Bull and improved sperm capability of fertilization.

• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.457-465
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• 2007

In this paper, polymer-modified repair materials using polymer dispersions with six repair methods are prepared with various polymer-cement ratios, and tested for compressive and flexural strengths through each curing condition such as dry cure, water cure, and freezing and thawing cyclic action. And, the adhesive interface between the polymer-modified mortar and mortar substrate is observed by a scanning electron microscope. From the test results, the compressive and flexural strengths of cement mortar repaired by polymer-modified mortar are improved with a rise in the polymer-cement ratio regardless of the type of polymer and curing conditions. Such an improvement in the strengths of polymer-modified repair materials to ordinary cement mortar is explained by the high adhesion of polymer-modified mortar. Strength reduction of polymer-modified repair materials after freezing and thawing cyclic actions is recognized, but it is lower than that of unmodified mortar. Especially, cement mortar repaired by polymer-modified mortar with a St/BA emulsion has good strength properties compared with those of SBR latex and PA emulsion. Accordingly, it is judged that polymer-modified mortars with a St/BA emulsion are possible to use as repair materials to ordinary cement mortar and concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.51-59
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• 2019

There is increasingly more research focusing on the application of FRP reinforcing bars as an alternative material for steel reinforcing bars, but most such research look at short term behavior of FRP reinforced structures. In this study, the microscopic analysis and tensile behavior of Basalt and Glass FRP bars under freezing-thawing and alkaline conditions were experimentally evaluated. After 100 cycles of the freezing and thawing, the tensile strength and elastic modulus of FRP bars decreased by about 5%. In the case of microstructure of FRP bars during the initial 20 days, no significant damages of FRP bar sections were found under $20^{\circ}C$ alkaline solution; however, the specimens immersed in $60^{\circ}C$ alkaline solution were found to experience resin dissolution, fiber damage and the separation of the resin-fiber interface. In the alkaline environment, the strength decrease of about 10% occurred in the environment at $20^{\circ}C$ for 100 days, but the tensile strength of FRPs exposed for 500 days decreased by 50%. At temperature of $40^{\circ}C$ and $60^{\circ}C$, an abrupt decrease in the strength was observed at 50 and 100 days. Especially, the tensile strength decrease of Basalt fiber Reinforced Polymer bars showed more severe degradation due to the damage caused by dissolution of resin matrix and fiber swelling in alkaline solution. Therefore, in order to improve the long-term performance of the surface braided FRPr reinforcing bars, surface treatment is required to ensure alkali resistance.