• 콘크리트학회논문집
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• 제11권4호
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• pp.117-127
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• 1999

In concrete incorporating high volume ground granulated blast-furnace slag that has frozen at early age, to evaluated the results of resistance to freezing and thawing is very difficult because the hydration of the concrete increases over the duration of rapid freezing and thawing test. Hence, the dynamic modulus of elasticity of specimens after freezing and thawing will be favorable results unless the hydration effect is taken into consideration. In this study, a method of evaluating to the resistance to freezing and thawing of concrete subjected freezing at early age, in which the effect of hydration is modified for its increase during rapid freezing and thawing test, is investigated.

• 한국가축번식학회지
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• 제13권3호
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• pp.141-148
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• 1989

The effects of seeding method and optimum time for freezing embryos according to the developmental stages on embryo survival rates after rapid freezing were determined using the FDA-test. The summarized results are as follows : 1. In the rapid freezing of embryos, the sucrose added medium together with Co-seeding or non-seeding showed the FDA scores of 4.67 and 4.20, respectively, but, raffinose addition obtained FDA scores of 4.27 and 3.97. 2. The developmental stage of embryos at freezing was most critical on the survival of embryos after thawing. Higher FDA scores were obtained in the order of blastocyst stage(4.94), morula stage(3.82) and ealy stage(2.65) in sucrose added medium. The same trend was observed in the raffinose added medium with an order or 4.91, 4.47 and 2.32. 3. Microscopic study of embryo before freezing and post-thawing indicated that the embryo showed shrinkage within 5 minutes after the embryo was transfer to the freezing medium. When thawed embryo was tranfered to the dilution medium, swelling of the embryo was observed and there after it reshrank indicating the removal of cryoprotectant from the embryo. The size of the embryo recovered to the original state when it was moved into a PBS-solution.

• 한국가축번식학회지
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• 제21권2호
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• pp.95-102
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• 1997

The studies on the carried out to investigate the effective concentration of cryoprotectant agents and sucrose by one-step straw method of bovine embryos. The follicular oocytes were cultured in TCM-199 medium containing 10 IU/ml PMSG(Sigma, USA), 10 IU/ml hCG(Sigma, USA), 1$\mu\textrm{g}$/ml $\beta$-estradiol(Sigma, USA) and 10% FCS for 24~48 hrs in incubator with 5% CO2 in air at 38.5$^{\circ}C$ and then matured oocytes were again cultured for 12~18 hrs with motile capacitated sperm by preincubation of heparin. The bovine embryos following dehydration by cryoprotective agents and various concentrations of sucrose were directly plunged into liquid nitrogen and thawed in 3$0^{\circ}C$ water. Survival and in vitro developmental rate was defined as devellpmental rate on in vitro culture or FDA-test. The results are smmarized as followes : 1. The high in vitro developmental rates of bovine frozen embryos after rapidly thawed in freezing medium was attained 2.0M glycerol, 2.0M DMSO, 1M or 2.0M propanediol. 2. The high in vitro developmental rates of bovine frozen embryos after rapidly thawed in freezing medium was obtained single cryoprotectant(6.7~17.4%) than mixed cryoprotectants(6.7~16.7%). 3. In vitro developmental rate of bovine embryos after rapid frozen-thawing in the freezing medium added 0.25M and 0.50M sucrose were higher cleavage rate than those of sucrose concentration of 0.75M and 1.00M. 4. The freezing methods on in vitro developemental rates of bovine embryos was attained slow freezing method(9.70~15.6%) higher than rapid freezing method(9.4~13.3%).

• 한국수정란이식학회지
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• 제9권1호
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• pp.65-71
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• 1994

This study were carried out to investigate the effective concentration of cryoprotectant agents and sucrose by one-step straw method, and to determine the optimum thawing temperature and equilibration time of frozen bovine embryos. The bovine embryos following dehydration by cryoprotective agents and a various concentration of sucrose were directly plunged into liquid nitrogen and thawed in 3O$^{\circ}C$ water. Survival rate was defined by FDA test. The results are summarized as follows : 1. The survival rate of bovine embryos thawed after rapid freezing in the freezing medium containing a various kinds of cryoprotective agents added 0.25M and O.50M sucrose were 28.6% and 25.0%, 35.1% and 31.6%, 32.4% and 24.4%, 34.2% and 28.2%, 18.9% and 17.6%, 14.7.% and 21.6%, respectively. 2. The survival rate of bovine embryos thawed after rapid freezing in the freezing medium containing a various concentration of sucrose added 1.5M and 2.OM glycerol, i.5M and 2.OM DMSO and 1.5M and 2.OM propanediol were 22.9~37.8%, 2O.7~31. 3%, 19.2~30.0% and 17.2~25.0%, respectively. 3. The temperature thawed at 2$0^{\circ}C$ after rapid freezing of bovine embryos resulted in a significantly higher embryos survival rate than did at 3$0^{\circ}C$ and 35$^{\circ}C$. 4. The equilibration time on the survival rate of bovine embryos was attained after short period of time(2.5~5 min.) in the freezing medium higher than long period of time (1O~20 min.).

• 한국구조물진단유지관리공학회 논문집
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• 제5권1호
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• pp.131-140
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• 2001

In general, the deterioration induced by the freezing and thawing cyclic in concrete structures often leads to the reduction in concrete durability by the cracking or surface spalling. If it can prediction of concrete deterioration subjected to cyclic freezing and thawing, we can rationally do the design of mix proportion in view of concrete durability and the maintenance management of concrete structures. Therefore in this study a prediction method of deterioration for concrete structures subjected to the irregular freezing and thawing is proposed from the results of accelerated laboratory freezing and thawing test using the constant temperature condition and the in-situ weathering data. Furthermore, to accurately predict the concrete deterioration, a method of modification for the effect of hydration increasing during rapid freezing and thawing test is investigated.

• 한국수정란이식학회지
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• 제4권1호
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• pp.1-13
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• 1989

This paper reviews the most important steps that have generated consistent progress in principles and developmental progress of embryo cryopreservation, and also study on freezing procedure and its application by conventional method and current improved method for freezing procedure and its appilcation of embryo cryopreservation in farm animals. Four were of particular interest: 1.The transport of water across the ccli membrane (zona pellucida) during freezing and thawing accordinglyplays a role in determing whether the celi survives. This movement of water is controlied mainly by extracellular phase changes and by the nature and concentration of any cryoprotective agent present. Therates of cooling, freezing and warming, and the intervals over which they are applied are further decisi've factors in determining whether a cryopreservation procedure allows survival after thawing. 2.The first successful deep freezing experiments with sheep morula and blastocysts during the seventies were based on the early procedures used for mouse embryos.Current research during the eighties is developed with the aim of simplifying and improving current procedures such as one-step dilution and rapid or ultra-rapid cooling by using the model of laboratory animals. 3.The conventional method for the embryo cryopreservation is described. An alternative to this method which may result in high survival and also in reducing of the freezing and thawing time is done by combing a permeable cryoprotectant such as glycerol, DMSO or propanediol and a non-permeable compound such as sucrose, trehalose, raffinose or lactose. 4.Finally a different approach to the preservation of embryos, named vitrification, is introduced. This procedure depends upon the ability of concentrated solutions of cryoprotective agents such as glycerol and propanediol to supercool to very low temperature (-196$^{\circ}C$) during rapid cooling before solidifying without formation of ice. However, more complete data are necessary for successful vitrification of blastocysts.

• 한국수산과학회지
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• 제44권6호
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• pp.665-670
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• 2011

The rotifer Brachionus plicatilis is one of the most important food organisms in aquaculture. The resting eggs produced by mictic female rotifers are easily stored and hatched, making them useful as the starter for the mass culture of rotifers in marine larval culture. This study examined the optimum preservation method for resting eggs to ensure a high hatching rate. To produce resting eggs, the marine rotifer B. plicatilis was cultured with Nannochloris oculata (KMMCC 16). The resting eggs were harvested and cryopreserved using 5% and 10% methanol (MeOH), dimethylsulfoxide (DMSO), and glycerol as cryoprotectant agents (CPAs). The cryopreservation comprised slow or rapid freezing and the resting eggs were stored for one month in liquid nitrogen ($-196^{\circ}C$). The resting eggs were also dried at different temperatures (30, 40, and $50^{\circ}C$) and for different times (1, 2, and 3 h). In general, the hatching rates of the resting eggs preserved with CPA were higher than those without CPA and the slow freezing method was better than the rapid freezing method. However, the optimum CPA concentration for the hatching rate of the resting eggs varied with the freezing method and kind of CPA, and the CPA also affected the viability of the resting eggs. Dried resting eggs had a high, rapid hatching rate over 80%. The moisture content of the resting eggs cryopreserved in liquid nitrogen affected the hatching rate. Drying at $30^{\circ}C$ for 1 hour resulted in a high hatching rate of the resting eggs. In conclusion, drying at $30^{\circ}C$ for 1 hour and preservation in liquid nitrogen with the slow freezing method, without CPA, is recommended for a high hatching rate (ca. 95%) of rotifer resting eggs.

• Clinical and Experimental Reproductive Medicine
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• 제27권2호
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• pp.191-200
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• 2000

Objective: This study was carried out to compare the effects of the stepwise exposure treatments on the morphological normality, fertilization and blastocyst formation rate of the frozen-thawed mouse mature oocytes by vitrification or ultra-rapid freezing and to use as a fundamental data for the cryopreservation of human oocytes. Materials and Methods: The morphological normality and fertilization rates of the vitrified and ultra-rapid frozen mouse mature oocytes after three-stepwise exposure treatments (1step, 3step and 5step) were observed. After choosing the 3step exposure treatment groups, we observed the morphological normality and fertilization, blastocyst formation rate of the vitrified and ultra-rapid frozen mouse mature oocytes. Results: The morphological normality and fertilization rates of the vitrified mouse mature oocytes after three-stepwise exposure treatments (1step, 3step and 5step) were 75%, 85%, 88% and 58%, 61 %, 54% respectively. There were no significant differences among treatments(p>0.05). The morphological normality and fertilization rate of the control was 92% and 65%. There were no significant differences in fertilization rate among control and treatments (p>0.05). The morphological normality and fertilization rates of the ultra-rapid frozen mouse mature oocytes after three-stepwise exposure treatments (1step, 3step and 5step) were 83%, 83%, 84% and 75%, 63%, 56% respectively. There were no significant differences among treatments (p>0.05). The morphological normality and fertilization rate of the control was 95% and 67%. There were no significant differences among control and treatments (p>0.05). The morphological normality and fertilization rate of the vitrified or ultra-rapid frozen mouse mature oocytes after 3step exposure treatment were 69% and 75%, respectively. The blastocyst formation rate was 60% and 57%. The results did not differ significantly between vitrification and ultra-rapid freezing (p>0.05). Conclusion: As known in the above results, there were no significant differences in the fertilization and blastocyst formation rate of the frozen-thawed mouse mature oocytes by vitrification or ultra-rapid freezing among the control and treatments. It is suggested that vitrification and ultra-rapid freezing method were effective for the cryopreservation of mouse mature oocytes.

• Journal of Animal Science and Technology
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• 제55권5호
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• pp.417-425
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• 2013

동결 닭 PGCs의 생식계열 키메라를 이용한 생체에의 복원을 실용화 하기 위해서는, 닭 PGCs의 동결보존기술의 향상에 의해 동결 및 융해 후의 많은 생존세포를 확보 하는 것과, 생식계열 키메라의 제작효율을 높이는 것이 반드시 필요하다. 닭 PGCs는 배양 5.5일령의 닭 원시생식선으로부터 채취하고, ACS 방법에 의해서 순수 닭 PGCs를 분리했다. 닭 PGCs의 동결보존실험결과 다음의 4종류의 동결방법을 각각 비교 검토했다. 1. 플라스틱 스트로에 의한 완만동결법 (SF), 동결보호물질은 2M 에틸렌 글리콜 (EG), 2. 스트로에 의한 급속동결법 (RF), 8M EG + 7% PVP, 3. 동결용 Cryotube에 의한 SF, 2M EG, 4. 튜브에 의한 SF, 10% DMSO. 동결 및 융해 후의 PGCs의 생존율은 각각 76.4%, 70.6%, 80.5%, 78.1%로 관찰되었다.

• 한국가축번식학회지
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• 제21권2호
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• pp.103-109
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• 1997

The studies on the carried out to investigate to determine the optimum thawing temperature and equilibration time and 1 step straw method of frozen bovine embryos. The follicular oocytes were cultured in TCM-199 medium containing 10 IU/ml PMSG(Sigma, USA), 10 IU/ml hCG(Sigma, USA), 1 $\mu\textrm{g}$/ml $\beta$-estradiol(Sigma, USA) and 10% FCS for 24~48 hrs in incubator with 5% CO2 in air at 38.5$^{\circ}C$ and then matured oocytes were again cultured for 12~18 hrs with motile capacitated sperm by preincubation of heparin. The bovine embryos following dehydration by cryoprotective agents and various concentration of sucrose were directly plunged into liquid nitrogen and thawed in 3$0^{\circ}C$ water. Survival and in vitro developmental rate was defined as developmental rate on in vitro culture or FDA-test. The results are summarized as followes : 1. The equilibration time on in vitro developmental rates of bovine embryos was attained after short period of time(2.5~5 min.) in the freezing medium higher than long period of time (10~20 min.). 2. The temperature thawed at 3$0^{\circ}C$ after rapid freezing of bovine embryos resulted in a significantly higher in vitro developmental rate than did at 2$0^{\circ}C$ and 35$^{\circ}C$. 3. The thawing time on in vitro developmental rates of bovine embryos was attained after short period of time(1~5 min.) in the freezing mediuim higher than long period of time(10min.). 4. The in vitro developmental rates of bovine embryos after rapid frozen-thawing by 1 step straw method in the freezing medium added 1.5M, 2.0M glycerol, DMSO, propanediol and 0.25M, 0.50M, 0.75M, 1.00M sucrose were 12.5~19.4%, 10.0~15.6%, 9.1~13.8% and 6.7~12.9%, respectively.