In the food industry, freezing storage has been an important process for maintaining the properties of food materials. In order to maintain the quality of blanched Colocasia esculenta (L.), Schott stem, packaging, freezing, and thawing methods were optimized by determinations of the physicochemical properties. For the comparison of packaging method, Colocasia esculenta (L.) Schott stem packed by air containment had the lowest significant differences of properties such as hardness and drip loss compared to the control samples. Overall, the drip loss of Colocasia esculenta (L.) Schott stem had lower value at fast freezing rate (immersion freezing). Considering the result of the drip loss, high frequency thawing was more effective than other thawing methods. Therefore, it was supposed that samples treated by air-containing packaging, immersion freezing, and high frequency thawing used the optimal method to maintain the original quality of Colocasia esculenta (L.) Schott stem.

The aim of this study was to compare the effects of different thawing methods including; refrigerated at 4℃ for 6 hr, soaked in 15℃ water for 40 min, exposed to room temperature (25℃) for 4 hr, and microwaved (600 W) for 2 min on the water-soluble nutritional component and meat quality trait of Hanwoo beef. The thawing beef by the refrigerated method resulted in significantly lower cooking loss, drip loss and loss of water-soluble vitamin B group, whereas the water-soaked method had higher loss of vitamin B group (p<0.05). Furthermore, total aerobic counts and coliforms were significantly lower in the meat samples thawed by the refrigerated method than that in the samples thawed by the other methods when stored for 6 days at 4℃. However, the thiobarbituric acid reactive substance (TBARS) content was found significantly (p<0.05) higher in the microwaved method than that in the other thawing methods. Based on the results obtained in the present study, it is concluded that the thawing methods had remarkable impact on the water-soluble nutritional components, quality properties and storage stability of meat. Therefore, the present study recommends that the thawed meat needs to be consumed and should not be stored for long time due to the acceleration of its quality deterioration

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 ˚) and in room temperature(25 ˚). Drip loss of maesil thawed in microwave oven was 3.2±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˚)and room temperature (25˚)

This study were carried out to investigate the effective concentration of cryoprotective agents and sucrose by one-step straw method, and to determine the optimum thawing temperature and equilibration time of frozen porcine embryos. The porcine embryos foflowing dehydration by cryoprotective agents and a various concentration of sucrose were directly plunged into liquid nitrogen and thawed in 3 water. Survival rate was defined by FDA test. The results are sunnnarized as follows : 1. The survival rates of porcine embryos after ultrarapid frozen4hawing in the freezing medium with a various concentration of glycerol, DMSO and propanediol added 0.25M sucrose were higher survival rate than those of sucrose concentration of 0.50M. 2. The survival rates of porcine embryos after ultrarapid ftozen4hawing in the freezing medium added 0.25M and 0.SOM sucrose were higher survival rate than those of sucrose concentration of 0.75M and 1.00M. 3. The temperature thawed at 2 and 3 resulted in a significantly higher embryos survival rate after 72 hrs in culture than did at 35. 4. The equilibration time on the survival rate of porcine 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.).

The objective of this experiment was to study some possibilities to simplify freezing, thawing and transfer procedure of one-step straw method comparing with the conventional methods using bovine embryos. The previous work are also designed to investigate the thawing effect by development stage and its quality using the embryos. Results obtained were summarized as follows: 1. A total of 87 embryos from 14 donor cows were frozen-thawed and an average of frozen embryo/donor was 6.2. 2. The survival rates of morula stage(65.4%) were higher than those of blastocyst stage(57.l%) and vice versa in rate of morphological recovery (80% vs 95.4%). However. no significant difference was denoted between them. 3. In difference between the groups of good quality and poor quality. good quality was resulted in a significantly higher embryo survival rate(75%) and recovery rates(95%) than poor quality(P<0.0l). 4. In effects of non-permeable sugar dilution in added to l.0M glycerol. higher survival rates were orderd in sucrose. lactose, raffinose and xylose. But lactose-raffinose, sucrose-trehalose and xylose in added to 2.OM glycerol. 5. The highest survival rates were obtained by direct plunge into the liquid nitrogen with 3.OM concentration both of glycerol and trehalose. 6. The survival rates in vitro condition of one-step and direct plunge methods(75%-87.5%) were significantly higher than those of multiple steps (21.4-52.6%) in in vitro (P<0.0l). However, the results of single-step were critical in comparing to other steps of final pregnant conformation.

Concrete structures are exposed to complex degradation environments depending on their environmental characteristics. The concrete members of bridges are exposed to water and salt by rivers and oceans, and there is always a possibility of freezing and thawing damage in the upper and lower part of the bridge due to the continuous heat and heavy snow in summer and winter. In this study, a freeze-thaw test method which indirectly evaluates the strength reduction of concrete according to the repeated cycle of freezing and thawing was proposed, and the strength reduction rate was measured by using the concrete specimen. As a result, the concrete strength was reduced by 20% in freeze-thaw test method. In the future, it can be used as a basic data of the study on strength of each cycles.

본 고는 동절기 이후 무근 콘크리트의 상부에서 쉽게 발생하는 스케일링 현상에 주목하여 무근 콘크리트의 동해 발생원인을 고찰하고, 이에 대한 내구성을 향상시키기 위한 방안을 기존문헌조사를 통하여 1) 강도향상, 2) 진공배수공법 적용, 3) 흡수방지재 시공의 방법을 선정하였다. 그 후 각 방법의 동결융해저항성 향상 평가를 정량적으로 평가하기위하여 동결융해 시험을 통한 상대동탄성계수를 측정하였다. 그 결과 1), 2)번의 경우 동탄성계수가 약 15% 향상, 3)의 경우 강도에 따라 7~13%향상됨을 실험적으로 확인하였다. 따라서 상기의 방법 모두 무근 콘크리트의 동결융해 저항성 향상에 유효한 방법으로 판단되며, 이를 통해 무근콘크리트의 빈번히 발생하는 품질저하 및 이로인한 유지보수비용 절감을 도모할 수 있을 것으로 사료된다.

Recently, scaling of pavement concrete is becoming problem by excessive use of deicer. The current study measured durability of concrete not considering multi-deterioration using design and construction mixing used general concrete pavement.