• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.621-624
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• 2006

In this study, the repair method using PVA fiber reinforced mortar evaluated on durability performance. Test of salt injury, carbonation, freezing-thawing, chemical attack, permeability was performed As for the test results, it was found that durability performance of the repair method using PVA fiber mortar showed more better than the existing repair method. Therefore, appling on the repair method using PVA fiber reinforced mortar, the repaired concrete structures can be increased to service life.

• Structural Engineering and Mechanics
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• v.69 no.1
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• pp.69-75
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• 2019

The plates made of two materials joined to each other having the different coefficient of thermal expansions are frequently encountered in the industrial applications. The stress analysis of these members under the effect of high-temperature variation has great importance in design. In this study, the stress analysis of the experimental model developed for the problem considered here was performed by the method of photothermoelasticity. The thermal strains were formed by the mechanical way and these were fixed by the strain freezing method. For the stress measurements, the method of slicing is applied which provides three-dimensional stress analysis. The analytical solution in the literature was compared with the related stress distribution obtained from the model. Moreover, the axisymmetric finite element model developed for the problem was solved by ABAQUS and the results obtained here compared with those of the experimental model and the analytical solution. As a result of this study, this experimental method and numerical model can be used for these type of thermal stress problems which have not been comprehensively analyzed yet.

• Korean Journal of Animal Reproduction
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• v.20 no.2
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• pp.207-214
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• 1996

To examine the developmental capacity of manipulated embryos after ultrarapid refreezing and thawing, mouse embryos were biopsied at 4-cell stage, frozen twice at 4-cell and morula stages, respectively, and then transferred to rec-ipients. Single blastomeres were biopsied from 4-cell embryos by a modified aspiration method. Biopsied 4-cell embryos were equilibrated into freezing medium at room temperature for 2.5 min, loaded into 40 $\mu$I of freezing medium in 0.25 ml plastic straw and then directly immersed into liqiud nitrogen. Freezing medium for 4-cell embryos consisted of 4.0 M ethylene glycol and O.25 M sucrose in dPBS supplemented with 6 mg/lm BSA. Morulae were frozen into freezing medium containing 5.0 M glycerol instead of ethylene glycol. Thawing was conducted by agitating each straw in 3TC water for 20 sec. The c content of each straw was expelled into 0.5 ml of dilution medium, which consisted of 0.25 M sucrose and 3 mg/ml BSA in dPBS. The thawed embryos were rehydrated in dilution medium for 10 min, washed 3 times with dPBS and then cultured in M16 medium at 37$^{\circ}C$, 5% CO$_2$ in air. Blastocysts that developed from frozen or refrozne biopsied embryos were transferred to recipients on Day 3 of pseudopregnancy, respectively. In vitro and in vivo developmental rates of the biopsied and intact 4~cell embryos after freezing and thawing were 78 (10l/130) and 25% (10/40), and 91 (114/125) and 30% (12/40), respectively. Although the rates of in vitro development of biopsied and intact embryos to blastocyst stage were significantly different after freezing and thawing (P

• Restorative Dentistry and Endodontics
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• v.35 no.4
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• pp.285-294
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• 2010

The purpose of this study was to evaluate the viability of periodontal ligament cells of rat teeth after low-temperature preservation under high pressure by means of MTT assay, WST-1 assay. 12 teeth of Sprague-Dawley white female rats of 4 week-old were used for each group. Both side of the first and second maxillary molars were extracted as atraumatically as possible under tiletamine anesthesia. The experimental groups were group 1 (Immediate extraction), group 2 (Slow freezing under pressure of 3 MPa), group 3 (Slow freezing under pressure of 2 MPa), group 4 (Slow freezing under no additional pressure), group 5 (Rapid freezing in liquid nitrogen under pressure of 2 MPa), group 6 (Rapid freezing in liquid nitrogen under no additional pressure), group 7 (low-temperature preservation at $0^{\circ}C$ under pressure of 2 MPa), group 8 (low-temperature preservation at $0^{\circ}C$ under no additional pressure), group 9 (low-temperature preservation at $-5^{\circ}C$ under pressure of 90 MPa). F-medium and 10% DMSO were used as preservation medium and cryo-protectant. For cryo-preservation groups, thawing was performed in $37^{\circ}C$ water bath, then MTT assay, WST-1 assay were processed. One way ANOVA and Tukey HSD method were performed at the 95% level of confidence. The values of optical density obtained by MTT assay and WST-1 were divided by the values of eosin staining for tissue volume standardization. In both MTT and WST-1 assay, group 7 ($0^{\circ}C$/2 MPa) showed higher viability of periodontal ligament cells than other group (2-6, 8) and this was statistically significant (p < 0.05), but showed lower viability than group 1, immediate extraction group (no statistical significance). By the results of this study, low-temperature preservation at $0^{\circ}C$ under pressure of 2 MPa suggest the possibility for long term preservation of teeth.

• Korean Journal of Animal Reproduction
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• v.23 no.1
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• pp.75-84
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• 1999

This study assessed development in vitro of pronuclear(PN) stage embryos cryopreserved by the method of either vitrification or slow freezing, by using of different cryoprotectants, and equilibration and cooling rate, in rabbit. Ethyleneglycol- ficoll- sucrose(EFS) or ethyleneglycol- polyvinylpyrrolidone - galactose- (EPG-I) for vitrification, and EPG- II for slow freezing as cryoprotectant were used. The pronuclear embryos were exposed to EFS for 0 to 5 min and diluted with D-PBS and/or pre-dilution with 0.5 M sucrose. To examine the viability of frozen-thawed embryos, PN embryos were co-cultured with bovine oviductal epitherial cell(BOEC) for 5 days to hatching blastocyst stage in 39 $^{\circ}C$ 5% $CO_2$incubator. The results obtained were as follows: The dilution with 0.5 M sucrose and D-PBS after the exposure to EFS for 1.0 min resulted in no significant(P＜0.05) decrease in the development of PN embryos to hatching blastocyst(72.0%), compared with controls. The development of PN embryos cryopreserved to hatching blastocyst was not significantly (P＜0.05) different between EFS for 1.0 min(72.0%), EPG-I for 1.0 min(72.0%) and EPG-II for 30 min(66. 7%). The post-thaw development of PN embryos to hatching blastocyst was similarly very low as 6.1% and 11.5% in vitrification with EFS and slow freezing with EPG-II, respectively. The incidence of post-thaw zona-crack in PN embryos cryopreserved by slow freezing with plunging to liquid nitrogen at －35$^{\circ}C$ was signicantly(P＜0.05) higher(25.0%), compared with －85$^{\circ}C$ (1.9%). These results indicated that the rabbit PN embryos could be cryopreserved with either vitrification or slow freezing procedure, and frozen PN embryos could be successfully developed in vitro to haching blastocyst. but the post-thaw development of cryopreserved PN embryos was still very low under the present conditions.

• Korean Journal of Animal Reproduction
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• v.25 no.4
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• pp.409-419
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• 2001

This study was to examine whether the in vitro friability, motility and intact acrosome of frozen-thawed bovine and human sperm can be improved by adding Pentoxifylline (PF) or Fertilization Promoting Peptide (FPP). Human semen was frozen ultra-rapidly using Test yolk-buffer (TYB) freezing medium. Additive (PF, FPP) effects in frozen-thawed bovine and human sperm were analyzed by microscopic count for sperm motility and coomassie brilliant blue staining method f3r sperm acrosome intact. The in vitro motility of frozen-thawed bovine sperm with 5 mM PF treatment group (50.0%) was significantly higher than that of control (34.0%) (P＜0.05). In the frozen-thawed bovine sperm was examined, the intact acrosome rate of 50 nM FPP treatment (49.0%) was significantly higher than those of control (30.0%) and 25 nM FPP (38.0%) treatment groups (P＜0.01). In human semen, when in vitro motility of sperm with PF addition prior to freezing was examined, the result of 5 mM treatment group (51.0%) was significantly higher than those of control and 2.5 mM treatment group (39.0, 40.0%) (P＜0.01). In addition, 50 nM (75.5%) FPP adding in all treatment procedures for human semen freezing (before freezing, freezing and after thawing) was significant effect on maintenance of the sperm intact acrosome percentage (control: 45.0; 25 nM: 53.0; 100 nM: 68.0%) (P＜0.01). Also, the intact acrosome rate of human sperm with FPP (65.0%) was significantly higher than that with PF (43.0%) (P＜0.05), although sperm motility was slightly higher in PF treatment group. These results suggest that improved sperm motility and intact acrosome of frozen thawed bovine and human sperm can be obtained by addition of PF or FPP, and that the enhanced in vitro viability, motility and intact acrosome can be obtained by addition of FPP in all semen freezing procedures.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.107-117
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• 1975

Alaska pollack caught in the Northern Pacific Ocean and frozen aboard vessel are skipped to the plant and processed into frozen fillets. In the present paper quality changes during thwaing, refreezing and storage at $-20^{\circ}C$ are discussed. Natural, running-water, vacuum and steam thawing were employed as thawing methods. And contact plate, air blast, immersion in dry ice-alcohol solution freezing and storage at $-5^{\circ}C$ were applied to refreeze the thawed fillets. As quality factors content of drip released, salt-extractable protein, VBN, DNA in the drip and pH were determined. In addition, bacteriological tests were also carried out along with the whole process. In thawing of round material, the vacuum thawing was more effective than any other method, resulting in drip, salt-extractable protein $(N\%)$, VBN and DNA as $4.4\%,\;1.82\%,\;16.21mg\%$ and $13.70\;{\mu}g/ml$, respectively. Storage at $-5^{\circ}C$ as refreezing method yielded lower in drip and DNA content but similar to or slightly higher in both salt-extractable protein and VBN, which might postulate that the quality of the frozen fillet depends not largely on the secondary freezing but on the conditions of thawing and primary freezing. It seemed that most of the bacterial flora in thawed fillet came from skin and viscera of fish, worker's hands, utensils and other processing facilities, since sanitary indicative bacteria were not detected in the frozen flesh of round Alaska pollack. Bacterial quality of fillet varied with thawing methods, vacuum thawing appeared more sanitative compared with other methods as natural, running-water, and steam thawing. Bacterial colonies isolated from the thawed fillet were composed of $73.8\%$ Gram negative rod shape, $4.9\%$ Gram positive rod shape, $18.0\%$ cocci, and $3.3\%$ yeast. Decreasing rate of coliform group of the fillet during the storage at $-20^{\circ}C$ for 30 days was more than $70\%$ and that of plate count was less than of coliform group.

• Journal of Animal Science and Technology
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• v.55 no.5
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• pp.427-434
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• 2013

This study was conducted to establish methods for preserving chicken primordial germ cells (PGCs) for long-term storage in liquid nitrogen and for developmental engineering or preservation of species. The purpose of this study is to clarify the effects of fetal bovine serum (FBS) or chicken serum (CS) treatment on the viability of cryopreserved PGCs from Korean Native Chicken (Ogye). PGCs separated from a germinal gonad of an early embryo at day 5.5-6 (stage 28) were suspended in a freezing medium containing freezing and protective agents (dimethyl sulfoxide (DMSO), ethylene glycol (EG) and glycerol). The values from 0, 5, 10, and 15 % DMSO plus FBS treatment were 21.6, 30.36, 36.42, 50.39, and 48.36 %, respectively. The viability of PGCs after freeze-thawing was significantly higher for 10% EG plus FBS treatment than for 10% EG + FCS treatment (p<0.05) (64.36% vs. 50.66%). This study establishes a method for preserving chicken PGC that enables systematic storage and labeling of cryopreserved PGC in liquid nitrogen at a germplasm repository and an ease of entry into a database. In the future, the importance for this new technology is that poultry lines can be conserved while work is being conducted to improve the production of germline chimeras.

• Journal of Animal Science and Technology
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• v.49 no.2
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• pp.287-294
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• 2007

The present study was to conducted the sexing efficiency and accuracy of bovine embryo by LAMP (Loop-mediated isothermal amplification) method, the development of the biopsied embryos into re- reformation and the freezability of these blastocysts by slow-freezing and vitrification. In vivo embryos were superovaluted with gonadotropin(Antorin R-10) for 4 days combined with progestrone releasing intravaginal(CIDR) insertion in Hanwoo donors, and in vitro embryos were used blastocyst embryos at Day 7 or Day 8 after post-insemination in vitro. The biopsy of bovine embryo was carried out in a 80μl drop with Ca2+-Mg2+ free D-PBS and the viability of biopsied embryos were evaluated in IVMD medium at over 12 h culture time in 5% CO2 incubator.For embryo sexing, about five or seven blastomeres were isolated from in vitro and in vivo embryos at blastocysts with microblade. and were then subjected to LAMP. The survivability of biopsied embryos were no difference in the development rate to re-formation of blastocysts between in vivo and in vitro embryos(100% and 90% respectively). The rates of sexed embryos were compared according to two groups, the female rate was lower than that the male in the in vivo and in vitro embryos(46% vs, 54% and 40% vs, 60%, respectively). However, there were no difference in the overall sexing ratio between the two groups. The survivability of frozen-thawed sexed embryos were lower in the in vitro than in vivo embryos in the slow-freezing(Group 1) and vitrification method(Group 2), (41.7% vs. 58.8% and 57.1% vs, 77.8. respectively).

• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.272-278
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• 2016

Porous pavements are recommended as a Low-Impact Development (LID) method which is a strategy to develop a water cycle as close to a natural state as possible, and to solve the urban impervious surface problems. Porous pavements can yield a solution if it provides a more permeable surface with extra space to contain extra water from building roofs. But there are few applications in Korea because of a lack of recognition and experience. Highway engineers are mainly concerned about the infiltration of water into pavement structures. They worry about the weakening of the asphalt mixture and subgrade, and freezing during the winter season due to the infiltration of water. Meanwhile, hydrological experts doubt the effects of the amount of water to control during the flooding season, and environmental experts prefer a non-point pollution treatment system established beside highway. In this study, from reviewing the history and the body of literature about porous pavements, conclusions regarding the most advanced technologies were made. First, traditional thickness designs can be used for porous pavement, no extra distresses was found by weakening and freezing during the winter season. Second, hydrological design can be made by controlling the thickness of the pavement and the outlet of water. Third, the treatment efficiency of non-point pollution of porous pavements is not worse than any other method. Importantly, it's a more eco-friendly solution because of its lower requirement for de-icing agents.