• 한국임상수의학회지
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• 제19권1호
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• pp.80-85
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• 2002

This study was performed to investigate the freezomg condition especially focused on extender composition to achieve good post-thaw viability and motility of canine sperm. Semen were collected from 6 male dogs which had been proved to be fertile in the past and were treated for freezing. Equex-STM paste was contained in both the 1st(3%) and the 2nd(7%) diluent and the 2nd diluent was added to the 1st diluent following glycerol equilibration for an hour and a half. To investigate the effect of Equex-STM paste in the extender on post-thaw canine sperm characteristics, the post-thaw viability, motility, and HOS(Hypoosmotic swelling) values were evaluated according to the different composition of extender with or without Equex-STM paste, thawing conditions, and different thawing media added to thawed semen. 1. Canine sperm removed from seminal plasma and frozen )n Sweden extender containing Equex showed higher post-thaw viability, motility, and HOS values than those frozen in the extender containing Equex-STM paste with seminal plasma and those frozen in the extender without Equex and seminal plasma. 2. Canine sperm frozen in Sweden extender containing Equex-STM paste with 5% glycerol showed higher post-thaw viability, motility, and HOS values than those frozen with 3%, 8% glycerol or 5% DMSO. 3. The canine semen frozen in Sweden extender with 5% glycerol and Equex-STM paste showed higher viability, motility, and HOS values when thawed at $70^{\circ}C$ for 8 seconds than when thawed at $37.5^{\circ}C$ for 1 min and at $18-20^{\circ}C$ for 5 min. 4. TFC (tris -fructose-citrate) and PB S (phosphate buffered saline) medium added immediately to thawed canine semen brought better viability, motility, and HOS values for the sperm than those semen added with TGC(tris-glucose-citrate) and no medium. These results indicated that Equex-STM paste in Sweden extender for freezing the canine sperm which were removed from seminal plasma brought good post-thaw viability and motility of canine sperm. Also of the freezing conditions of canine sperm with the same extender containing Equex, the concentration of 5% glycerol, the thawing condition at $70^{\circ}C$ for 8 sec, and TFC and PBS medium added to the thawed semen brought better post-thaw viability and motility of canine sperm than the other conditions used in this study.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.1097-1100
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• 2008

본 연구에서는 순환골재 콘크리트의 부착 내구성을 평가하기 위하여 동결융해 피해를 받은 순환굵은골재 콘크리트의 부착성능을 실험적으로 검토하였다. 콘크리트는 순환골재 품질기준에서 제시하는 품질 하한치(흡수율 : 3.0%, 절건밀도 : $2.5g/cm^3$)를 만족하는 순환굵은골재를 사용하여 레미콘 배합에 의해 생산하였으며, 부착실험체는 표준 인발시험 중에서 철근을 수직방향으로 배근한 형태로 제작하였다. 또한 실험변수는 순환굵은골재의 치환률(0, 30, 60, 100%)과 동결융해 사이클을 변수로 수행하였다. 실험결과에 의하면 동결융해 조건하에서 순환굵은골재 치환률에 따른 콘크리트의 부착성능은 차이가 없는 것으로 나타났다. 또한 AE제를 사용한 천연 및 순환골재 콘크리트는 동결융해에 의한 부착강도 저하가 발생하지 않았다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.621-624
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• 2008

콘크리트 구조물에 적용되는 보수재료는 적용되는 환경요인에 따라 품질특성이 다르게 나타난다. 국내의 보수재료에 대한 내구성 평가는 다양한 환경요인에 따른 시험법의 미비로 내구성에 대한 품질성능이 확보되지 않은 실정이다. 본 연구에서는 국내에서 생산되는 보수재료에 대하여 적용환경에 따른 동결융해저항성능을 BS EN 13687에 준하여 시험하였고, 국내시험규격(KS F 4716)과 비교 분석하였다. 연구결과 건습반복과 염수침지동결융해 시험 후의 부착강도 값은 보수재료의 종류 및 시편의 크기에 따라 다소 큰 차이가 나타났다. 보다 양호한 보수재료의 품질관리를 위해서는 적용환경에 따른 다양한 동결융해저항시험방법에 대한 규격제정이 요구된다.

• Asian-Australasian Journal of Animal Sciences
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• 제17권9호
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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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.129-136
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• 1998

In this study, lightweight aggregates were developed to see the possible application as a structural uses. For the evaluation purpose, several testings were conducted to compare the physical characteristics between the controlled lightweight aggregates and other lightweight aggregates purchased from different sources. The tests included property changes of fresh concrete and strength characteristics of hardened concrete for both normal and high strength ranges. In addition, a experiment was performed to analyze the freezing and thawing resistance of new lightweight aggregate concrete against other lightweight aggregate concrete against other lightweight aggregate concretes with some experimental parameters such as lightweight aggregates, curing conditions, and water-cement ratio. The test showed that the new lightweight aggregate could be used structural components. Continuous study will be planned for future evaluations.

• 상하수도학회지
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• 제14권1호
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• pp.117-126
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• 2000

Solubilization pretreatments were conducted to enhance the anaerobic digestion of the waste activated sludge. Four pretreatment techniques including heating, sonication freezing and thawing, and enzyme addition were employed to solubilize the waste activated sludge under various conditions. Thermal pretreatment by heating showed the highest efficiency compared with other methods, and freezing and thawing was confirmed as a feasible alternative of solubilization as well as the pretreatment of dewatering. There is a clear correlation between the solubilization efficiency of the waste activated sludge and the gas production. Batch digestion results showed the cumulative gas production as much as four times after thermal pretreatment as compared with that by the control sludge without pretreatment. As a result, hydrolysis or solubilization pretreatment might play a significant role in the high rate digestion of the waste activated sludge.

• 한국건축시공학회지
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• 제5권2호
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• pp.97-105
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• 2005

Concrete structures in the marine environment often deteriorate in the early stage of their service life because of contact with various aggressive conditions. In recent years, the researches on the concrete in the marine environment have been carried out to increase their service life. In this experimental study, the concrete specimens were prepared with various adding contents of inorganic antifouling agent$(0\~3.0wt\%)$ composed of some fluosilicate solution. For evaluation of the properties of concretes containing inorganic antifouling agent, various tests such as setting time, slump loss, compressive strength, water absorption rate, fleering and thawing resistance and SEM of concrete, were conducted. As the results, physical and chemical properties of concretes were improved with an adding of inorganic antifouling agent. From the results of various tests, the optimal adding contents of antifouling agent was $1.0wt\%$.

• 동아시아식생활학회지
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• 제14권5호
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• pp.443-448
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• 2004

In order to investigate the optimal factors for frozen dough production, the freezing and thawing condition such as temperature and time, storage period and the effect of ingredient addition were determined. A pre-fermentation of dough at 30℃ for 120 minutes was appeared to be the best for the production of frozen dough. The dough was frozen at -18℃ and then stored for 7 days. The quality of frozen dough was found to be optimal when thawed at 30℃ for 80 minutes. As ingredient of frozen dough, an addition of 3% of yeast and 4% of butter was good as well as the addition of skim milk and sugar in terms of fermentation capacity after thawing.

• Geomechanics and Engineering
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• 제29권3호
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• pp.349-357
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• 2022

Abnormal climate events are occurring frequently around the world. In particular, cold waves and heavy snow lead to damage and deterioration of facilities, which can cause loss of life or property damage, such as shortening the lifespan of facilities. Therefore, it is very important to prepare an appropriate maintenance system and to establish a strategy to cope with abnormal weather conditions. In this study, laboratory freezing experiments were performed to analyze the freeze-thaw characteristics affecting the tunnel concrete lining, and heat flow analysis was carried out based on the test results. Based on these experimental and theoretical analysis results, quantitative freeze-thaw evaluation criteria for tunnel concrete linings were proposed.

• 한국건설순환자원학회논문집
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• 제6권1호
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• pp.59-65
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• 2018

콘크리트 구조물은 다양한 환경에 노출되며, 부식환경인 해안가에서는 매립 보강재의 부식저항성 및 동결융해 저항성이 함께 평가되어야 한다. 최근 개발된 FRP Hybrid Bar는 내부에 강재가 있으며 유리섬유와 에폭시가 코팅된 보강재인데, 기존 FRP Bar보다 탄성계수가 높은 장점이 있다. 본 연구에서는 FRP Hybrid Bar에 대하여 동결융해 300 cycle 시험을 수행한 뒤, 내부식특성과 중량결손율, 및 부착특성을 평가하였다. 300 cycle 이후 2번 에폭시를 코팅한 경우에 규사의 손실이 가장 적었으며, 외관의 결함이 관측되지 않았다. 부착강도는 규사코팅에 따른 조도의 증가로 FRP Hybrid Bar의 경우 일반철근의 120 % 수준을 나타내었다. 또한 일반철근을 가진 시편의 부착력은 부식시간 3일에서는 0.86 ~ 0.89 배, 5일에서는 0.35~0.38 배로 크게 감소하였으나, 동결융해 전후의 FRP Hybrid Bar를 가진 콘크리트 공시체는 부착강도의 감소가 발생하지 않았다.