• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.533-536
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• 2001

When fresh concrete is exposed to low temperature, the concrete may suffer frost damage due to freezing at early ages and strength development may be delayed. One of the solution methods for resolving these problems is to reduce freezing temperature of concrete by the use of chemical admixture called Accelerators for freezing resistance. In this study, we investigate the effect on strength development of cement mortar using accelerators for freezing resistance with the variance curing condition. As the result of this study, the mortar using accelerators for freezing resistance show that continuously strength development in curing condition of -5$^{\circ}C$. And compressive strength under the variance temperature condition was higher than fixed temperature condition in same maturity.

• Korean Journal of Agricultural Science
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• v.40 no.3
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• pp.197-202
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• 2013

This study was aimed to find the storage potential of low temperature adapted shiitake mushroom under freezing temperature ($-3^{\circ}C$). Fresh shiitake mushroom was harvested at late Feb. and cooled to target temperature, $-3^{\circ}C$ in the cooling room for 24 hr. Cooled mushroom were then placed in plastic boxes, wrapped with plastic film ($30{\mu}m$), and stored at $-3^{\circ}C$ for 2 months. Weight loss of mushroom was ranged from 2.1 to 3.2%. Dry weight per unit fresh weight, however, was slightly increased because of moisture loss. Firmness of fruit body increased from $0.95kg/cm^{-2}$ (before storage) to $1.13kg/cm^{-2}$ (after 2 month storage). About half amount of starch was lost during 2 month storage. The amount of total and reducing sugars remained relatively constant. After storage, freshness of mushroom was recovered by thawing treatment. When recovered mushroom were packaged with styrofoam tray and PVC wrapping, and exposed to ambient and $10^{\circ}C$, respectively, brown spot on the gill of fruit body was found and slight decay symptom was also found at ambient temperature only but not at $10^{\circ}C$. Results indicated that low temperature adapted shiitake mushroom has a storage potential under freezing temperature ($-3^{\circ}C$). Freezing storage technology of fresh shiitake mushroom will contribute the increase of storability up to 2 months.

• International Journal of Industrial Entomology and Biomaterials
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• v.11 no.2
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• pp.99-105
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• 2005

We investigated oviposition and colony development of Bombus ignitus and B. terrestris depending on different pollen. In five kinds of pollen blend, the colony development in fresh-freezing pollen blend produced in Korea (Korea-FFP) was the best performance, although egg-laying characteristics is lower than that of pollen blend for oviposition imported from Korppert company (Kopport-FOP). The Kopport-FOP proved that it was suitable to use for oviposition of bumblebees. The Korea-FFDP, freezing dried-fresh pollen blend produced in Korea, is lower rather than the Korea-FDP although it is similar to the KopportFOP in colony development. It is not efficient to use commercial pollen for bumblebee because it is expensive in cost. The dried pollen blend for honeybee feeding imported from China (China-DP) was not suitable for rearing of bumblebee because it did not form colony although the worker emerged. In types of pollen, the oviposition and colony development of B. ignitus were not affected by the fresh-freezing pollen and dried-freezing pollen. This result also indicated that dried pollen, dried in the shade for 5 - 6 days, is possible to use as commercial pollen for bumblebee reproduction.

• Reproductive and Developmental Biology
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• v.28 no.3
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• pp.155-159
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• 2004

This study was carried out to investigate the general characteristics and viability of sperm after freezing and thawing and the pregnancy rates after artificial insemination with thawed semen. The rates of viable sperm after slow and rapid freezing were 87.4±3.85% and 70.8±4.45%, respectively which were significantly lower than that of fresh semen control (91.7±3.45%). The mean concentration of epididymal sperm after dilution in 1.0 ml saline and. 3.0 ml extender in a various concentrations of cryoprotectants was 124.5±48.3 x 10/sup 6/ (range of 45 x 10/sup 6/ to 280 X 10/sup 6/ /ml). There was a significant difference not in the percentage of acrosome-reacted sperm, but in the percentage of capacitated sperm, between fresh and frozen-thawed epididymal semen. When frozen-thawed after diluting with tris-buffer extender containing glycerol, DMSO and ethylene glycol with concentration of 2 to 6%, the rates of epididymal sperm exposed to different cryoprotectants ranged from 14.4±4.7% to 20.7±5.8%, 17.8±5.2% to 36.5±4.9%, and 14.4±4.6% to 18.5±5.3%, respectively which were lower compare to fresh semen control. The pregnancy rate after artificial insemination with frozen semen was 70.6%, whereas that with fresh semen was 90.0% in dogs with naturally induced estrus.

• Korean Journal of Veterinary Research
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• v.32 no.1
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• pp.143-151
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• 1992

Sixty Four fresh and 142 frozen embryos of dairy cattle were transferred to synchronized dairy, beef or Korean Native Cattle nonsurgically at National Animal Breeding Institute from 1985 to 1990. The results obtained were as follows ; 1. The pregnancy rate of fresh embryos(39.1%) was higher than that of frozen embryos(32.4%) and average pregnancy rate was 34.5%. 2. The pregnancy rate of grade 1 embryos was higher than that of grade 2 embryos for both fresh(41.3% vs 33.3%) and frozen embryos(35.4% vs 25.6%). 3. The pregnancy rate according to development stage of fresh embryos was increased with maturity as 29.2%, 33.3%, 50.0% and 54.5% for morula, early blastocyst, blastocyst and expanded blastocyst, respectively. For frozen embryos, the pregnancy rate of blastocyst(44.4%) was higher than those of morula(31.3%) and early blastocyst(28.0%). 4. The pregnancy rate according go recipient-donor synchrony for fresh embryos was higher when the recipients exhibited estrus 1 day earlier than the donors(43.8%) than when the recipients exhibited estrus 1 day later than the donors(38.1%) or when the recipients and donors exhibited estrus at the same time(37.0%). For forzen embryos, the pregnancy rate was decreased when the recipients and donors exhibited estrus at the same time(37.9%), when the recipients exhibited estrus 1 day later than the donors(32.0%) and when the recipients exhibited estrus 1 day earlier than the donors(23.5%), in sequence. 5. The pregnancy rate of heifers was higher than that of cows for both fresh(50.5% vs 37.9%) and frozen embryos(39.7% vs 25.7%). 6. The pregnancy rate according to recipient breed for fresh embryos was higher in dairy cattle(42.1%) and beef cattle(40.%) than in Korean Native Cattle(33.3%). For frozen embryos, the pregnancy rate was decreased beef cattle(39.1%), dairy cattle(30.3%) and Korean Native Cattle(14.3%), in sequence. 7. The pregnancy rate according to equilibrium steps of glycerol and freezing rate was higher when transferred after 3-steps equilibrium and freezing by the rate of $0.3^{\circ}C$/min from $-6^{\circ}C$ to $-35^{\circ}C$ and $0.1^{\circ}C$/min to $-38^{\circ}C$(39.4%) than when transferred after 6-steps equilibrium and freezing by the rate of $0.5^{\circ}C/min$ from $-6^{\circ}C$ to $-30^{\circ}C$(30.3%).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.11 no.2
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• pp.91-95
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• 1978

Histological changes of the abalone muscle occurring in the process of freezing as well as thawing were investigated, and its results were compared to the histological structure of fresh muscle. The muscles of the abalone were mainly composed of smooth muscle fibres, and its morphological structures is similar to those of the top shell. Mechanical damgage of the muscle fibres caused by freezing were not observed while a number of small ice crystals were found between the muscle fibres. The damage by thawing was not much remakable compare to the destruction of muscle fibres of fish.

• Food Science of Animal Resources
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• v.41 no.6
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• pp.1012-1021
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• 2021

This study evaluated the effect of freezing rate on the quality characteristics of pork loin to establish an objective standard for rapid freezing. To generate various freezing rates, three air flow rates (0, 1.5, and 3.0 m/s) were applied under three freezing temperatures (-20℃, -30℃, and -40℃). Based on the results, freezing rates ranged from 0.26-1.42 cm/h and were graded by three categories, i.e, slow (category I, >0.4 cm/h), intermediate (category II, 0.6-0.7 cm/h) and rapid freezing (category III, >0.96 cm/h). Both temperature and the air flow rate influenced the freezing rate, and the freezing rate affected the ice crystal size and shear force in pork loin. However, the air flow rate did not affect thawing loss, drip loss or the color of pork loins. In the comparison of freezing rates, pork belonging to category II did not show a clear difference in quality parameters from pork in category I. Furthermore, pork in category III showed fresh meat-like qualities, and the quality characteristics were clearly distinct from those of category I. Although the current standard for rapid freezing rate is 0.5 cm/h, this study suggested that 0.96 cm/h is the lowest freezing rate for achieving meat quality distinguishable from that achieved with conventional freezing, and further increasing the freezing rate did not provide advantages from an energy consumption perspective.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.401-412
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• 2016

It is extremely difficult to apply conventional grouting methods to subsea tunnelling construction in the high water pressure condition. In such a condition, the rapid artificial freezing method can be an alternative to grouting to form a watertight zone around freezing pipes. For a proper design of the artificial freezing method, the influence of salinity on the freezing process has to be considered. However, there are few domestic tunnel construction that adopted the artificial freezing method, and influential factors on the freezing of the soil are not clearly identified. In this paper, a series of laboratory experiments were performed to identify the physical characteristics of frozen soil. Thermal conductivity of the frozen and unfrozen soil samples was measured through the thermal sensor adopting transient hot-wire method. Moreover, a lab-scale freezing chamber was devised to simulate freezing process of silica sand with consideration of the salinity of pore-water. The temperature in the silica sand sample was measured during the freezing process to evaluate the effect of pore-water salinity on the frozen rate that is one of the key parameters in designing the artificial freezing method in subsea tunnelling. In case of unfrozen soil, the soil samples saturated with fresh water (salinity of 0%) and brine water (salinity of 3.5%) showed a similar value of thermal conductivity. However, the frozen soil sample saturated with brine water led to the thermal conductivity notably higher than that of fresh water, which corresponds to the fact that the freezing rate of brine water was greater than that of fresh water in the freezing chamber test.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.7
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• pp.965-970
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• 2016

This study was conducted to determine the effects of freezing and supplementation of molasses (M), lactic acid bacteria (LAB) and LAB+enzyme mixture on chemical and nutritional composition of sunflower silage (SF). Sunflower crops were harvested (at about $29.2%{\pm}1.2%$ dry matter) and half of fresh sunflower was ensiled alone and half was frozen (F) at $-20^{\circ}C$ for 7 days. Silage additives were admixed into frozen SF material. All samples were ensiled in glass jars with six replicates for 90 days. The treatments were as follows: i) positive control (non-frozen and no additives, NF), ii) negative control (frozen, no additives, F), iii) F+5% molasses (FM), iv) F+LAB (1.5 g/tons, Lactobacillus plantarum and Enterococcus faecium, FLAB); v) F+LAB+enzyme (2 g/tons Lactobacillus plantarum and Enterococcus faecium and cellulase and amylase enzymes, FLEN). Freezing silage increased dry matter, crude ash, neutral detergent fiber, and acid detergent lignin. The organic matter, total digestible nutrient, non-fiber carbohydrate, metabolizable energy and in vitro dry matter digestibility were negatively influenced by freezing treatments (p<0.05). In conclusion, freezing sunflower plants prior to ensiling may negatively affect silage quality, while molasses supplementation improved some quality traits of frozen silage. Lactic acid bacteria and LAB+enzyme inoculations did not effectively compensate the negative impacts of freezing on sunflower silage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.3
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• pp.175-178
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• 2004

We here report that the muscle of 'gukmeri-bok' puffer fish (Takifugu vermicularis radiatus) is intoxicated after freezing and thawing processes even though it is not toxic when it is fresh. This study was carried out to investigate the effect of different freezing and thawing conditions as well as the effect of the presence of skin or viscera on the intoxication of muscle of 'gukmeri-bok' puffer during freezing and thawing process. As a result of this investigation, thawing condition, but not freezing conditions or periods played an important role in muscle intoxication. Tetrodotoxin secretory grands exist in the skin of toxic puffer fish, the skin was more responsible for the muscles intoxication than the viscera during the freezing-thawing process. In other words, no toxicity was measured in the muscle of skinned-frozen specimens even when thawed. According to this result, it is recommended that the skin and viscera must be removed before being frozen for edible purpose. Otherwise, when a whole fish should be frozen, alternative half-thawing and removal of skin from frozen specimens is recommended.