• Clinical and Experimental Reproductive Medicine
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• v.27 no.3
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• pp.283-289
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• 2000

Objective: The study was performed to compare the survival rate and the development of day 2 mouse embryos which had freezing procedures done. Methods: We used three different vitrification solutions (EFS, VS14, DPS) and a ultrarapid freezing solution (UFS) for cryopreservation of day 2 mouse embryo. Results: We tested toxicity by exposing embryos to vitirification solutions and a ultrarapid freezing solution. The survival rates are 100%, 97.8%, 95.6% and 100% (EFS, VS14, DPS and UFS). After cultured for 96 hours, hatching rates of each group are 93.5% (no freezing), 95.6% (EFS), 86.4% (VS14), 93.0% (DPS), and 93.0% (UFS). There is no significant differences among groups. The survival rates after thawing cryopreserved embryos are 80.2%, 91.7%, 69.5%, 0% and 91.8% (slow freezing, EFS, VS14, DPS and UFS). Also cultured for 96 hours, the hatching rates are 93.5% (no freezing), 84.1% (slow freezing), 93.9% (EFS), 48.5% (VS14) and 70.1% (UFS). Conclusion: The survival rates of vitrification in EFS solution and ultrarapid freezing are higher than slow freezing (p<0.05). The hatching rate of vitrification in EFS solution cultured for 96 hours is highest, so vitrification of day 2 mouse embryos in EFS solution considered as more effective for cryopreservation.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.9
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• pp.1291-1295
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• 2004

Histology and transmission electron microscopy studies were carried out on buffalo muscles that were subjected to repeated freeze-thaw cycles at -10 and $-18^{\circ}C$. In the first freeze thaw cycle ($-10^{\circ}C$) structures of muscle showed slight change and closely resembled to those of normal muscle. There were frequent gaps in the half way across the fibres and some cracks in individual fibre were also noticed in second freeze thaw cycle. In the muscle frozen at $-18^{\circ}C$, more pronounced shrinkage with extensive damage of fibres with tearing was observed. The interfibrillar gaps were wider, shrinkage and tearing of the fibres were more distinct after second freeze-thaw cycle. After the second cycle, the interior portion showed large scale degradation of the ultrastructure. Our studies of buffalo muscle showed that under the proper condition, little structural damage takes place in the meat histology and ultrastructure under repeated freeze-thaw conditions. This study adds continued weight to the evidence that limited freeze-thaw cycles will not deteriorate the quality of meat.

• Magazine of the Korea Concrete Institute
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• v.4 no.3
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• pp.157-166
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• 1992

해수환경하의 콘크리트 구조물은 동결융해의 반복에 의한 물리적인 침식과 해수중에 용존하는 각종의 이온들의 침투로 인한 화학적 침식에 의해 현저한 성능저하현상을 나타내는 것으로 알려져있다. 본 연구는 포졸란계 혼합재인 플라이 애쉬, 슬래그, 슬리카 흄과 폴리머계 혼합재인 Ethylene Vinyl Acetate(EVA), Styrene-Butadiene Rubber(SBR)를 사용하여 제조한 콘크리트 경화체의 해수환 경하에서 동결융해 저항성에 미치는 혼합재의 종류 및 첨가량의 영향, W/C의 영향을 비교 검토한 실험적 연구이다. 콘크리트의 동결융해 저항성을 위해서는 공기연행이 필수적이며, 공기연행시킨 경우 W/C가 낮을수록 동결융해 저항성이 우수하였다. 해수중에서의 동결융해 저항성은 슬래그분말을 첨가할 때 우수하였으며, 폴리머계 혼합재에서는 EVA가 우수한 결과를 나타내었다.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.973-978
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• 2001

In clod weather regions, a strong seasonal wind brings sea salts to the land. In addition to it, recently, the spreading amount of de-icing salts has increased numerously for the purpose of removing snow and ice. Thus the salts environment around concrete structures becomes so severe that various damages of concrete due to applied salts will be brought up. It is briskly carried out study on effects of do-icing salts on concrete in America, Japan, European countries. However, there are not test method for the deterioration of concrete subjected to both freezing-thawing and chloride attack in Korea. In this study, we conduct on test for the compound deterioration subjected to both freezing-thawing and chloride attack, in order to investigate effects of de-icing salts on the deterioration of concrete.

• Journal of the Korea Concrete Institute
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• v.12 no.2
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• pp.43-51
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• 2000

This study is to investigate for the frost resistance of high-flowing concrete using finely ground granulated blast-furnace slag with experimental parameters, such as type of binder, type of superplasticizer and method of curing. The resistance to freezing and thawing of high-flowing concrete by type of binder and superplasticizer is presented differently. Though the frost resistance of high-flowing concrete is satisfactory under standard condition, it is required that high-flowing concrete has entrained air like plain concrete. Because the critical spacing factor, being capacity of frost resistance, of high-flowing concrete is longer that of plain concrete, the frost resistance of high-flowing concrete, using finely ground granulated furnace blast slag, is superior to that of plain concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.85-88
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• 2001

Utilization of demolished-concrete as recycled aggregate has been researched for the purpose of substituing for insufficient natural aggregate, saving resources and protecting environment. There, however, are some problems that qualities of recycled aggregates are not only largely diverse, but also mechanical properties of recycled aggregate concrete decrease a little in comparison with those of natural aggregate concrete. In this study, the resistance to freezing and thawing of recycled aggregate concrete was highly different due to adhered mortar on recycled aggregate, and durability factor of concrete with NA SRA and DRA was decreased more than that of control concrete. However, durability factor of concrete with AA SRA was larger than that of control concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.755-760
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• 2002

The concrete structures in marine environment has been used type V cement(sulfate-resisting Portland cement), but according to the study results reported recently, the question has been raised for effect of the resistance to salt attack of the concrete using type V cement. It is increased the demands on the use of mineral admixtures such as fly ash, ground granulated blast-furnace slag instead of type V cement in order to improve the durability of concrete structures. Therefore, this study focused on the durability evaluation of concrete containing fly ash under marine environment, and the tests such as salt attack, carbonation, sulfate attack, and freezing-thawing were performed. Test results showed t]hat the resistance to salt attack, sulfate attack and freezing-thawing was improved, and the carbonation was in some disadvantage compared with normal concrete. Nevertheless, the durability of fly ash concrete would be maintained during the service life of structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.643-648
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• 2002

A research for recycling the demolished-concrete as concrete aggregate has been concerned in all over the world. There, however, are some problems that qualities of recycled aggregates are not only largely different, but also mechanical properties of recycled aggregate concrete decrease a little in comparison with that of natural aggregate concrete. In this study, the resistance of freezing and thawing of concrete using source-concrete recycled aggregate(SRN) and demolished-concrete recycled aggregate(DRA) was investigated. Futhermore a research for improvement of freeze and thaw durability of recycled aggregate concrete was performed. Relative dynamic modulus of elasticity of SRN and DRA recycled aggregate concrete was dropped 60% before 150 of freezing and thawing cycle, and was much lower than that of control concrete. Relative dynamic modulus of elasticity of recycled aggregate concrete was increased to decrease water-cement ratio, but the freeze and thaw durability of recycled aggregate concrete was not enough improved. Futhermore, when metakaolin and silica fume were repalced, the freeze and thaw durability of recycled aggregate concrete containg metakaolin was more improved than that of silica fume.

• Magazine of the Korea Concrete Institute
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• v.4 no.4
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• pp.115-122
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• 1992

폐쇄 폐콘크리트를 재활용한 재생콘크리트의 강도특성을 천연골재를 사용한 일반콘크리트와 비교하였다. 동결융해 처리수의 압축강도와 3점휨 재하시험하의 변형율을 측정하였다. 재생콘크리트는 동결융해 처리 후 압축강도 보존율이 더 높았다. 재생콘크리트는 또한 높은 변형율과 처짐에 민감함을 보였으나 파괴와 관련된 다른 성질들은 일반콘크리트와 유사하거나 더 좋은 것으로 나타났다. 그러므로 폐콘크리트를 구조용 콘크리트 제조에 재 사용이 가능할 것으로 보여진다. 그러나 실제 사용을 위하여는 콘크리트에 있어서 중요한 성질인 압축강도가 더 증진되어야 하며 최대 변형율도 보다 자세히 점검되어야 한다.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.215-218
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• 2003

In order to study the frost heaving characteristics of soil stabilitized with a quick lime, a cement and a briquette ash, frost heaving tests were performed with 2 kinds of soil sampled at Chonbuk-Do area. Frost heaving of no-stabilizing soil compacted with water content greater than optimum water content was increased as the frost period was increased but in case of samples with water content smaller than optimum water content, the frost period gave no affect about increase and decrease of the frost heaving. Both frost heaving of stabilizing and no-stabilizing soil with water content greater than optimum water content was decreased with the increase of the repetition number of freezing and thawing. There was no increase or decrease of frost heaving in the frost heaving test after 5 times of freezing and thawing.