• Smart Structures and Systems
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• 제17권1호
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• pp.45-58
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• 2016

Freezing and thawing cycles induce deterioration and strength degradation of concrete structures. This study presumes that a large quantity of contact-type defects develop due to the freezing and thawing cycles of concrete and evaluates the degree of defects based on a nonlinearity parameter. The nonlinearity parameter was obtained by an impact-modulation technique, one of the nonlinear ultrasonic methods. It is then used as an indicator of the degree of contact-type defects. Five types of damaged samples were fabricated according to different freezing and thawing cycles, and the occurrence of opening or cracks on a micro-scale was visually verified via scanning electron microscopy. Dynamic modulus and wave velocity were also measured for a sensitivity comparison with the obtained nonlinearity parameter. The possibility of evaluating strength degradation was also investigated based on a simple correlation of the experimental results.

• 한국수정란이식학회지
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• 제10권3호
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• pp.203-208
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• 1995

This study was carried out to efficiently use the ultrarapid freezing method in the cryopreservation of mouse ova. For this, the effects of dehydration method, oval vigour and $0^{\circ}C$ controlling method on post-thawing viability were investigated. Fresh mouse ova were dehydrated in mPBS with 3.5M DMSO and /or 0.25M sucrose, and directly immersed in L$N_2$ for ultrarapidly freezing. The frozen ova were thawed at 37$^{\circ}C$, rehydrated in mPBS with 0.25M sucrose, and then repeatedly washed in HAM's Fl0 before evaluating the morphological normality of frozen-thawed ova. The results obtained showed that there was difference between treatments in a experiment. 1) The post-thawing viability of ova dehydrated in multi-step (48.4$\pm$13.8%) was higher than that of ova in two-step (40.9$\pm$14.0%). 2) The post-thawing viability of fertilized ova (87$\pm$14.0%) was significantly(p<0.0l) higher than that of unfertilized ova (5.4$\pm$5.4%). 3) The post-thawing viability of ova dehydrated and rehydrated using a cooling machine (95.8$\pm$4.2%) was significantly(p<0.05) higher than that on ice(84.1$\pm$9.9). In conclusion, in order to efficiently cryopreserve ova in vitro with ultrarapidly freezing method, highly viable embryos should be selected, heavy osmotic shock to the dehydrating ova should be avoided, and embryos in high osmotic condition were dehydrated and rehydrated in a constantly low temperature.

• 한국식생활문화학회지
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• 제21권4호
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• pp.426-432
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• 2006

This study was conducted to investigate the changes in quality characteristics of frozen maesil according to thawing methods. The quality of maesil thawed in microwave oven was superior to those thaw in refrigerating temperature(5 $^{\circ}$) and in room temperature(25 $^{\circ}$). Drip loss of maesil thawed in microwave oven was 3.2${\pm}$0.2%. The total content of free sugars of maesil was 426.6 mg%, and 3% of them was decreased during thawing in microwave oven. The total content of organic acids was 5,297.2 mg%, and 2.5% of them was decreased during thawing in microwave oven. The total content of free amino acids was 281.4 mg%, and 2.1% of them was decreased during thawing in microwave oven. The principle ingredients of frozen maesil was stand for the lost contents of free sugar and a content loss of free organic acid and free amino acid were the fewest by thawing. Antioxidant effect for soybean oil and linoleic acid of maesil extract were expressd POV and TBA values. Antioxidative activity of fresh maesil extract was highest followed by maesil thawed in microwave oven, thawed in refreezing temperature (5$^{\circ}$)and room temperature (25$^{\circ}$)

• 한국도로학회논문집
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• 제15권3호
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• pp.65-74
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• 2013

PURPOSES: This study is to evaluate the dynamic modulus changes of permeable asphalt mixtures by using non-destructive impact testing method and to compare the dynamic moduli of permeable asphalt mixtures through repeated freezing and thawing conditions. METHODS: For the study, non-destructive impact testing method is used in order to obtain dynamic modulus of asphalt specimen and to confirm the change of dynamic modulus before and after freezing and thawing conditions. RESULTS : This study has shown that the dynamic moduli of asphalt concrete specimens consisting of 10%, 15% and 20% porosity are reduced by 11.851%, 1.9564%, 24.593% after freezing and thawing cycles. CONCLUSIONS : Non-destructive impact testing method is very useful and has repeatability. Specimen with 15% porosity has high durability than others.

• Archives of Plastic Surgery
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• 제42권2호
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• pp.143-149
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• 2015

Background Adipose tissue damage of cryopreserved fat after autologous fat transfer is inevitable in several processes of re-transplantation. This study aims to compare and analyze the survivability of adipocytes after thawing fat cryopreserved at $-20^{\circ}C$ by using thawing methods used in clinics. Methods The survival rates of adipocytes in the following thawing groups were measured: natural thawing at $25^{\circ}C$ for 15 minutes; natural thawing at $25^{\circ}C$ for 5 minutes, followed by rapid thawing at $37^{\circ}C$ in a water bath for 5 minutes; and rapid thawing at $37^{\circ}C$ for 10 minutes in a water bath. The survival rates of adipocytes were assessed by measuring the volume of the fat layer in the top layers separated after centrifugation, counting the number of live adipocytes after staining with trypan blue, and measuring the activity of mitochondria in the adipocytes. Results In the group with rapid thawing for 10 minutes in a water bath, it was observed that the cell count of live adipocytes and the activity of the adipocyte mitochondria were significantly higher than in the other two groups (P<0.05). The volume of the fat layer separated by centrifugation was also measured to be higher, which was, however, not statistically significant. Conclusions It was shown that the survival rate of adipocytes was higher when the frozen fat tissue was thawed rapidly at $37^{\circ}C$. It can thus be concluded that if fats thawed with this method are re-transplanted, the survival rate of cryopreserved fats in transplantation will be improved, and thus, the effect of autologous fat transfer will increase.

• 한국임상수의학회지
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• 제8권2호
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• pp.183-190
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• 1991

Pellet and straw methods in canine semen freezing are compared with respect to motility, viability and acrosome demage of sperm during each of the two major processing steps, to prior-freezing and to frozen-thawing. Senen was extended with a tris-buffered egg yolk contained 4% glycero1 Pellet freezing in the hole of dry ice and straw freezing on the surface of liquid nitrogen were carried out, respectively. The frozen semen 10 days after storage in liquid nitrogen container. wao thawed. In the comparison of two freezing methods, the straw freezing method with 42.7% in motility. 49.2% in viability and 0.186 acrosome score after thawing seems to be superior to the pellet freezing method with 31.2%, 34.5% and 0.314%, respectively. Sperm motility of processing step to frozen-thawing against decrease rate 12.67% to Prior freezing appeared of 33.84% and 49.37% in straw and pellet freezing and increase of 0.02 in acrsomal score to prior freezing appeared of 0.08 and 0.21 in straw and pellet freezing method to frozen-thawing

• 한국식생활문화학회지
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• 제17권1호
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• pp.90-95
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• 2002

This study was conducted to determine the desirable thawing method and storage time of Nokchaborijook(gruel made of barley, rice powder and Green tea) which made of optimum conditions as the 5.8% Green tea and 15 seconds grinding time. Decision on desirable storage time(10, 20, 30, 40, 50days), thawing method(water bath, microwave oven) of frozen Nokchaborijook were determined by sensory evaluation and physicochemical attributes. As the storage time became longer, moisture and flavonoid contents were decreased. Viscosity, the ratio of water seperation, spreadability of Nokchaborijook which stored at 30 days showed great differences between the two thawing method. Among the sensory characteristics, desirability for overall, flavor, and texture were decreased as the storage time became longer. As a result of consumer test, Nokchaborijook thawed at water bath was more desirable than Nokchaborijook thawed at microwave oven. According to the results, frozen Nokchaborijook can be using as a supplement of dietary fiber and flavonoid for the health and be using convenience food.

• 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.

• 한국터널지하공간학회 논문집
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• 제19권6호
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• pp.1059-1075
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• 2017

본 연구의 목적은 한랭지역에서 운용중인 지하 콘크리트 구조물에서 발생한 누수를 처리하기 위하여 기존 유도배수시스템의 동결융해 저항성을 평가하는 것이다. 유도배수시스템의 동결융해 저항성을 평가하기 위하여 4가지 종류의 유도배수시스템 시험체를 제작하여 실내 동결융해 실험을 수행하였다. 유도배수판의 모서리 부분과 유도배수판 연결부분에 적용할 방수재료인 Hotty-gel의 4가지 연결 방법에 대한 동결융해 저항성을 평가하였다. 또한 Hotty-gel이 부착된 유도배수판을 콘크리트 시편 표면에 고정시키 위한 2가지 방법에 대하여서도 동결융해 저항성을 평가하였다. 실내 동결융해 실험에서 1 cycle은 48시간(동결 24시간과 융해 24시간)을 적용하였고 동결과 융해 온도는 각각 $-18^{\circ}C$와 $10^{\circ}C$를 적용하였다. 4가지 종류의 Hotty-gel 연결 방법 중 유도배수판 모서리 부분에 적용된 'V'자형 홈을 가진 Hotty-gel 연결 방법에서만 동결융해 28 cycles (8 weeks)후 누수가 발생하였다. 나머지 3가지 종류의 Hotty-gel 연결 방법들에서는 누수가 발생하지 않았다. 2가지 고정방법 중 와셔, 나사못 및 칼브럭을 이용하여 유도배수판을 콘크리트 시편에 고정시키는 방법에서 누수가 발생하였다. 동결융해 10 cycles (3 weeks) 후 1개 지점에서 누수가 발생하였고 동결융해 28 cycles (8 weeks) 후에는 총 5개 지점에서 누수가 발생하였다. 시간이 경과함에 따라 누수 지점은 증가되지 않았지만 각각의 누수지점에서 누수량이 증가되었다. 공압타카, 타카핀 및 와셔를 사용한 고정방법에서는 누수가 발생하지 않았다. Hotty-gel연결 형상의 제작 시간 및 제작 방법을 고려한 제작 효율성에서 Hotty-gel 가로면 대각선 형상이 가장 높게 평가되었다. 고정방법에서 시공 시간 및 시공 방법을 고려한 시공 효율은 공압타카, 타카핀 및 와셔를 사용한 방법이 우수하였다.

• 한국식품영양학회지
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• 제16권4호
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• pp.359-364
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• 2003

Danish pastry의 반죽을 직날법으로 제조한 후 급속 냉동시켜 냉동고에 6주간저장하면서 1주단위로 5$^{\circ}C$, 1$0^{\circ}C$, 2$0^{\circ}C$에서 각각 해동하여 2차발효 후 오븐에서 구웠다. 냉동저장기간에 따른 생지의 효모 생균수를 측정하였고 냉동생지를 해동$.$발효$.$굽기$.$냉각과정 후 제품의 부피, 수분함량, 경도 등을 분석한 결과는 다음과 같다. 1. 효모는 냉동생지를 낮은 온도에서 해동할 때 높은 생존률을 나타냈다. 2. 빵의 부피는 냉동생지를 낮은 온도에서 해동할때 크게 나타났다. 3. 빵의 수분함량은 냉동생지를 높은 온도에서 해동할 때 높게 나타났으나 그 차이는 미미하였다. 4. 빵의 조직감은 냉동생지를 낮은 온도에서 해동할 때 부드러운 것으로 나타났다. 이상의 결과로 냉동생지의 해동시 5$^{\circ}C$의 낮은 온도에서 해동할 때 효모의 생존율, 빵의 부피, 조직감 등에서 양호한 결과를 나타냈다.