• 한국식품영양학회지
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• 제10권3호
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• pp.287-294
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• 1997

When bread making, the condition of thawing-fermentation for frozen dough were tested in variable temperature, and measured thawing-fermentation time and volume of frozen dough. L-Ascorbic acid (L-Aa) was added in frozen dough for the comparison test of develop volume in bread staling degree of baking bread were measured additive frozen dough which was stoppages in freezing, staling degrees were tested hardness with Rheometer. The test for comparison of thawing-fermentation time in variable temperature was shown the condition of dough conditioner at 3$0^{\circ}C$ was most effective for bread making, Because That condition was required very short time(74 min) But, in this comparison of volume in final products was shown the products in the condition of thawing-fermentation at 3$0^{\circ}C$ was smaller than the products at 5$^{\circ}C$(418 ml). The baking volume of L-Aa additive frozen dough which has under gone thawing-fermentation at 3$0^{\circ}C$, were shown baking volume of 420 ml in 2 weeks storage terms to 100 mg/kg L-Aa additive dough and shown baking volume of 454 ml in 4 weeks storage terms to dough of 200 mg/kg additive weight. Staling degrees of L-Aa additive frozen bread were measured with Rheometer. The hardness of 100 mg/kg L-Aa additive frozen bread was sown low level hardness in 1~2 weeks freezing term, 150 mg/kg L-Aa additive frozen bread was shown low level hardness in 3 weeks freezing term. In 4 weeks freezing term, 200 mg/kg L-Aa additive frozen bread was shown low level hardness compared with non-additive L-Aa frozen bread. In comparison of frozen bread quality, non-additive L-Aa products was better than additive L-Aa products in equality of baking shape and external apparence. But in total quality in external and internal apparence, additive L-Aa products was better than non-additive L-Aa products.

• Clinical and Experimental Reproductive Medicine
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• 제46권2호
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• pp.67-75
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• 2019

Objective: Sperm cryopreservation has been widely used in assisted reproductive technology, as it offers great potential for the treatment of some types of male infertility. However, cryopreservation may result in changes in membrane lipid composition and acrosome status, as well as reductions in sperm motility and viability. This study aimed to evaluate sperm DNA fragmentation damage caused by conventional freezing using the sperm chromatin dispersion test. Methods: In total, 120 fresh human semen samples were frozen by conventional methods, using SpermFreeze Solution as a cryoprotectant. Routine semen analysis and a Halosperm test (using the Halosperm kit) were performed on each sample before freezing and after thawing. Semen parameters and sperm DNA fragmentation were compared between these groups. Results: There was a significant decrease in sperm progressive motility, viability, and normal morphology after conventional freezing (32.78%, 79.58%, and 3.87% vs. 16%, 55.99%, and 2.55%, respectively). The sperm head, midpiece, and tail defect rate increased slightly after freezing. Furthermore, the DNA fragmentation index (DFI) was significantly higher after thawing than before freezing (19.21% prior to freezing vs. 22.23% after thawing). Significant increases in the DFI after cryopreservation were observed in samples with both normal and abnormal motility and morphology, as well as in those with normal viability. Conclusion: Conventional freezing seems to damage some sperm parameters, in particular causing a reduction in sperm DNA integrity.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.213-216
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• 2005

Salt attack and freezing & thawing test, one of the combined deterioration tests was performed to explore the mechanism of concrete structure deterioration under marine environment. Simple submerging test was proceeded to draw out its diffusion factor with salt water at the same time. Some of the mechanisms were driven with using three types of cements and four kinds of salt water concentrations. $\circ$ TBC was more durable than OPC or SRC for freezing and thawing action $\circ$ The higher chloride concentration of salt water was, the faster relative dynamic elastic modulus decreased and the higher the loss of weight was. $\circ$ The diffusion factor of TBC was smaller than those of TBC or SRC at simple submergence of concrete specimens into salt water.

• 한국지반신소재학회논문집
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• 제14권3호
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• pp.43-51
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• 2015

우리나라와 같이 4계절이 뚜렷한 지역은 동결 융해반복에 따른 강성도의 감소가 민간 시설물 인접 사면이나 산비탈면에 발생하였을 경우 안전율이 설계기준에 미흡하게 되는 현상이 발생되어 강우나 강설에 의한 산사태가 발생하여 큰 인명 및 재산피해로 이어질 우려가 있다. 이 연구에서는 동결 융해 반복에 따른 산지 사면의 안정성 변화를 알아보기 위하여 산지 사면의 표토에 분포하는 통일 분류법상의 SP와 SM계열의 흙시료를 채취하여 공시체를 제작하고 직접전단실험을 통하여 동토전단강도에 대한 특성을 분석하고, 수치해석적 방법을 활용하여 동결융해의 반복작용에 따른 화강풍화토의 강도감소특성과 흙시료의 동결 융해 적용시의 사면의 안정성의 변화를 검토하였다. 그결과 최대 전단응력은 약 10%정도의 감소율을 보였고, 사면 안정성해석결과 비동결시료에 비하여 요구안전율 이하의 경우가 있음을 확인하였다.

• 한국재난정보학회 논문집
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• 제9권4호
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• pp.469-475
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• 2013

이 연구의 목적은 고로슬래그 미분말을 혼입한 순환골재 콘크리트의 압축강도 및 동결융해 저항성을 평가하는 것이다. 이를 위하여 순환골재 대체율에 따라 고로슬래그 미분말 혼입률을 변수로 콘크리트 공시체를 제작한 후 이들의 압축강도 및 동결융해 저항성을 평가하였다. 고로슬래그 미분말 20% 혼입한 순환골재 콘크리트의 재령 28일 압축강도는 플레인 콘크리트보다 훨씬 우수하였고, 동결융해 300 사이클 시험 결과, 콘크리트의 공기량을 4~6% 유지하였을 때, 순환골재 대체율 및 고로슬래그 미분말 혼입률이 동결융해 저항성에 미치는 영향은 거의 없는 것으로 나타났다.

• 한국지반신소재학회논문집
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• 제13권3호
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• pp.49-58
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• 2014

본 논문에서는 계절적 환경변화로 인한 동결-융해 반복과정에 노출되는 옹벽구조물의 거동에 관한 축소 모형실험 연구 내용을 다루었다. 이를 위해 먼저 동결-융해 과정을 모사할 수 있는 모형 옹벽 실험 장치를 구현하고 실제 계절별 온도 변화 과정을 모사하였으며 다양한 흙의 함수비 및 뒤채움흙의 종류 등을 따른 영향 변화를 고찰을 위한 모형실험을 수행하였다. 실험 결과 계절별 온도변화에 따른 동결-융해 반복 과정은 옹벽의 변위를 증가시키고 토압을 증가시키는 것으로 검토되었다. 아울러 동결-융해 반복 사이클의 영향은 흙의 초기 함수비가 클수록 그리고 세립분을 많이 포함할수록 증가되는 것으로 검토되었다. 본 논문에서는 도출된 연구결과가 실무적 차원에서 지니는 의미에 대한 내용을 기술하였다.

• 한국가축번식학회지
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• 제18권1호
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• pp.15-23
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• 1994

This study was carried out to investigate the effects of concentration, kinds of cryoprotectants, equilibration time, optimum thawing temperature on the survival rate of rapidly frozen porcine embryos. The porcine embryos following dehydration by cryoprotectants containing sucrose were directly plunged into liquid nitrogen and thawed in 30, 35 or 37$^{\circ}C$ water bath, Survival rate was defined as development rate on in vitro culture or FDA-test. The results are summarized as follows : 1. The high survival rate of porcine frozen embryos after rapidly thawed in freezing medium was attained 2.0M DMSO, 2.0M glycerol, 2.0M propanediol, 1.5M ethyleneglycol. 2. The high survival rate of porcine frozen embryos after rapidly thawed in freezing medium was obtained using single cryoprotectant(16.6~40.0%) than mixed cryoprotectants(12.5~33.3%). 3. The eqilibration time on the survival rate of rapidly thawed porcine frozen embryos was attained after short period of time(15.0~33.3%) in the freezing medium higher than long period of time(9.10~30.0%). 4. The thawing temperature on the survival rate of rapidly thawed porcine frozen embryos was attained at 3$0^{\circ}C$ of thawing temperature(33.3~40.6%) in the freezing medium higher than 25 or 37$^{\circ}C$ of thawing temperature.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.227-233
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• 2008

Porous concrete has large continuous voids of 20-30 % by volume, and this concrete is attractive as environmental material in Japan i.e. permeable road pavement, river bank protection with vegetation and green roof system which influence thermal environment. It is necessary to confirm the frost resistance when constructing porous concrete structure in cold region. However applicable test method and evaluation criterion of porous concrete has not defined yet. Therefore, the object of this study is to investigate the frost resistance of porous concrete and this investigation attempts to address this concern by comparing 4 kinds of specified freezing and thawing tests methods (JIS A1148 procedure A/B and RILEM CIF/CDF test) in consideration of actual environment. RILEM freeze-thaw tests are different from JIS A1148 freeze-thaw tests, which are widely adopted for evaluating the frost resistance of conventional concrete in Japan, in water absorption, cooling rate, length of freezing and thawing period, and number of freezing and thawing cycles. RILEM CIF test measures internal damage and is primarily applicable for pure frost attack. CDF test is appropriate for freeze-thaw and de-icing salt attack. JIS A1148 procedure A/B showed extremely low frost resistance of porous concrete if the large continuous voids were filled with water and the ice expansion in the large continuous voids set in during cooling. Frost resistance of porous concrete was improved by mixing coarse aggregate (G7) which particle size is smaller and fine aggregate in JIS freezing and thawing tests. RILEM CIF/CDF test showed that freeze-thaw and de-icing resistance of porous concrete was seems to be superior in that of conventional concrete.

• 한국콘텐츠학회논문지
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• 제20권12호
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• pp.529-536
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• 2020

본 논문에서는 동결융해 작용을 받는 철근콘크리트 압축부재의 내구성 증진 효과를 알아보기 위하여 DFRCC(고인성 섬유 시멘트 복합재료)와 탄소섬유시트를 사용하여 보수·보강을 실시한 철근콘크리트 기둥을 대상으로 동결융해시험을 실시하여 압축강도 및 동탄성계수를 측정하고 비교 평가한 실험적 연구결과를 제시하였다. 이를 위해 100x100x400mm 크기의 기둥형 부재를 총 24개 제작하여 KS F 2456 및 KS F 2453에 따른 동결융해시험과 압축강도 시험을 각각 실시하였다. 부재단면에 4D10의 압축철근을 배치하였으며, 보수보강은 부재의 4면에 각각 실시하였다. 동결융해시험에서는 100, 200, 300Cycle의 각 세단계마다 동탄성계수를 산정하였다. 실험결과, 압축강도에서는 섬유시트를 사용한 경우가 DFRCC의 경우보다 약 5% 정도 큰 양상을 보였으며, 동탄성계수에서는 비슷한 결과를 나타내었다. 이는 공시체 크기에 비해 상대적으로 철근양이 많이 배근되어 간섭을 일으킨 것으로 추정되며, 실제 노후화된 기둥부재의 보수보강을 통한 실질적이고 추가적인 연구와 실험이 필요한 것으로 판단된다.

• 한국콘텐츠학회논문지
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• 제18권11호
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• pp.455-461
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• 2018

본 논문에서는 DFRCC 보수모르타르와 탄소섬유시트를 사용하여 보수보강을 실시한 철근콘크리트보를 대상으로 동결융해시험을 실시하여 휨강도 및 동탄성계수를 측정하고 비교 평가한 실험적 연구결과를 제시하였다. 이를 위해 $100{\times}100{\times}400mm$ 크기의 각주형 보를 총 14개 제작하여 KS F 2456에 따른 동결융해시험과 휨강도 시험을 실시하였다. 인장 및 압축측에서 각각 3-D10의 철근을 배치하였으며, 보수보강은 보의 3면에 각각 실시하였다. 동결융해시험에서는 각각 100 Cycle 및 200 Cycle에서 상대동탄성계수를 산정하였다. 실험결과, 휨강도에서는 탄소섬유시트를 사용한 경우가 DFRCC 보수모르타르의 경우보다 약 15% 정도 크게 나타났으며, 동탄성계수 측면에서는 큰 차이를 보이지 않았다. 이는 공시체 크기에 비해 비교적 많은 철근량이 배근되어 간섭효과가 나타난 것으로 추정되어 추가적인 실험과 연구가 필요한 것으로 판단된다.