• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.1
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• pp.69-76
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• 1995

Cold acclimation involves changes in gene expression. BN28 and BN115 are two genes which are regulated by cold temperature and assumed having roles in cold acclimation. The objectives of this experiment was to explore the expression of BN28 and BN115 under field conditions. Six winter cultivars were planted at three different dates during the fall. The expression of the genes was determined by northern blot analysis of total RNA taken from leaves 15 to 30 day-intervals after planting. The expression of the two genes was detected within 15 days after planting well before onset of freezing tolerance in plants. This suggestes either their expression was a prerequisite of the freezing tolerance or their expression was regulated by other environmental factors as well as temperature. Two genes showed a different expression pattern suggesting they had a different regulatory system. Although timecourse increase in expression of the cold-regulated genes was matched with increase in freezing tolerance, the difference of expression in cultivar level at specific times of measurement was not correlated with freezing tolerance at the moment.

• Journal of Embryo Transfer
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• v.12 no.2
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• pp.189-194
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• 1997

The ovaries of Korean native cows or heifers were obtained from a slaughter house and kept on 28~3O˚C and transported to laboratory within 2 hrs. The follicular oocytes were collected follicles. The oocytes were matured in vitro for 24 hrs. In TCM-199 supplemented with 35 $\pi$g /ml FSH, 10 $\pi$g /ml LH, 1 $\pi$g /ml estradiol-17 and granulosa cells at 39˚C under 5% $CO_2$ in air. The caudal epididymis of Korean native bulls were obtained from a slaughter house and transported to laboratory within 30 minutes. Swim-up of collected spermatozoa and freezing sperm was layered under 2ml fertilization B. 0. medium in two tissue culture tubes and held at a 45˚C angle for 0~2 hrs. They wrer fertilized in vitro by freezing sperm treated with heparin for 24 hrs, and then the zygotes were co-cultured in vitro with bovine oviductal epithelial cells for 7 to 9 days. The follicular oocytes recovered were classified into 41.7% as grade I, 51.5% as grade II and 6.8% as graed III. The number of oocytes recovered per ovary was averaged 8.3 and they were classifed into 2.3 as grade I, 2.5 as grade II and 2.3 as grade III. The cleavage rate of matured oocytes was significantly(P

• Korean Journal of Veterinary Research
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• v.34 no.4
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• pp.851-855
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• 1994

The semen from four male dogs which had been proven to be fertile in the past were frozen in a deep freezer at $-60^{\circ}C$ by simple freezing method using methanol and preserved at the same teperature for from 7 to 10 days. The semen were inseminated to 7 female dogs in estrus to find out the usability of this freezing method in artificial insemination for dogs. In addition, post-thaw motility and viability of sperm from two male dogs which had been fertile were also evaluated to investigate individual difference. Successful pregnancy was obtained by artificial insemination with canine semen frozen at $-60^{\circ}C$ by simple freezing method using methanol, namely, 3 bitches among 7 bitches which had been inseminated delivered puppies(42.8%). The average litter size of the whelping dogs were 4.3 puppies. The average post-thaw motility of canine sperm in the cases of conception was showen higher than those of non-conception(65.0% vs. 42.5%), along with the, same result in the average post-thaw viability between the two groups(53.3% vs, 27.5%). Individual difference of post-thaw motility and viability was obtained between two fertile dogs(p<0.05).

• Textile Coloration and Finishing
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• v.21 no.1
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• pp.10-20
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• 2009

The objective of this study is to investigate the efficacy of leaf powder colorants as substitutes for traditional fresh juice extract dyeing. Three kinds of leaf powder colorants were prepared by freeze drying method with or without deep freezing as pre-treatment: one powder colorant from fresh leaf juice with deep freezing; two kinds of powder colorant from fresh leaves with and without deep freezing. Their dyeing properties and storage stabilities were studied and compared with the traditional fresh juice extract dyeing. The presence of indigo in the powder colorants was confirmed by UV/Visible absorption spectra. They showed absorption peak at 602nm which was same with indigo absorption peak. Dyeing was done at low temperature around 6$^{\circ}C$. All three powder colorants produced B colors on silk fabrics, showing similar color to the one dyed traditionally with fresh juice extract. The powder colorants from leaves gave higher color strength than the powder from leaf juice. The powder colorant prepared from leaves with deep freezing was the most stable for long term storage as its color and color strength were not changed after 360 days. So, this was used for further dyeing to study the effects of concentration and repeat dyeing on color strength and colorfastness. Fastnesses to dry cleaning and rubbing were fairly good above 4 rating. Further study is needed to improve light fastness. It was concluded that the leaf powder colorant with deep freezing could be used as a substitute for traditional juice extract dyeing at all seasons.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.1
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• pp.126-131
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• 1999

We have got the following results from tests in the course of time retrogradation and taste change in bread with added flour of Angelica keiskei Koidz, which had been stored in room temperature (27±2oC), refrigerating(2±1oC) and freezing( 20±1oC), respectively. Bread with the added flour showed a little lower degree of retrogradation than control group, and every group in room temperature retrograded from the very first day. The degree of retrogradation of the group in refrigerating was far greater comparing with the group in room temperature. The longer bread was stored, the lower the degree of retrogradation was, and the higher the adding rate of the flour got, the later its retrogradation happened. Especially the flour of this vegetable's stem turned out to be the most effective in retarding its retrogradation. Group stored 30 days in freezing didn't show a wide difference in retrograde comparing with the group before storage. Preference for color and shape of the flour added bread stored in room temperatue, refrigerating and freezing did not change significantly from the group before storage. Although preference decreased for flavor, texture, mouth feel and overall quality with the lapse of time, flour added group improved in preference for these factors comparing with the control group. Above all, added flour of pretreated stem proved to be the most effective in the sensory tests. With respect to the storing method, the group stored in refrigerating showed greater preference for the texture and mouth feel over the groups in room temperature and freezing. Flavor preference of the group in freezing was the lowest of all.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.2
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• pp.230-238
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• 2016

This study examined the effects of freezing and thawing conditions on quality of Hanwoo bottom round. The beef samples were frozen by air blast freezing at $-20^{\circ}C$ or ethanol immersion freezing at $-70^{\circ}C$ and then stored at $-20^{\circ}C$ for 10 days. After 10 days of storage, the frozen samples were thawed with air blast thawing at $4^{\circ}C$ or water immersion thawing at $4^{\circ}C$ and subjected to subsequent analyses of drip loss, water holding capacity, thiobarbituric acid reactive substance (TBARS), volatile basic nitrogen (VBN), total aerobic bacteria, and microstructure. Drip loss significantly increased in samples treated with air blast freezing compared to ethanol immersion freezing, whereas freezing and thawing processes had no significant impact on water holding capacity of the samples. Thawing conditions had a much stronger influence on the TBARS and VBN of the samples than freezing conditions. There was no significant difference in the population of total aerobic bacteria among the four samples subjected to one freeze-thaw cycle. In addition, to analyze the effects of freeze-thaw cycle on the quality of beef, three freeze-thaw cycles were performed during storage. Multiple freeze-thaw cycles increased drip loss, TBARS, and VBN and decreased water holding capacity, accelerating microstructural damage. These data indicate that Hanwoo bottom round can be rapidly frozen and thawed by using ethanol immersion freezing and water immersion thawing methods with minimal impact on meat quality.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.4
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• pp.225-231
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• 2010

Extremely low values of the daily minimum temperature occurred in January 2010, ranging from -18 to $-29^{\circ}C$ at various locations growing peach trees in the Gangwon province. Due to the extreme cold temperature during the winter dormancy period of peach trees, the growth of the peach trees was damaged and the damaged areas increased as the extent of 17 to 144 ha. In order to provide information on mitigation measure of the cold temperature on the peach trees in the Gangwon province, we assessed the distribution of the damaged areas of growing the peach trees in 2010 and compared it with freezing risk estimated from the dormancy depth of the peach trees and the daily minimum temperature. The dormancy depth of 'Changhowon Hwando (Prunus persica (L.) Batsch)' ranged from -62 to -90 and the freezing risk was greater than 51%. The relationship between the freezing risk and the actual damaged area ratio showed reasonable agreement ($r^2$ of 0.5 with p < 0.01). The results imply that the estimates of the freezing risk based on the dormancy depth can be used as a mitigation measure to identify susceptible peach growing areas to freezing damage injury.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.6
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• pp.923-931
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• 2010

Effects of freezing period and chilling process after thawing on the physicochemical properties and palatability of hind shank meat from Korean native beef were investigated. There were no significant differences in the Hunter's color, volatile basic nitrogen (VBN) or collagen amount of hind shank meat upon freezing with vacuum packing at $-20^{\circ}C$ for 9 months. In addition, while pH, thiobarbituric acid (TBA) value, hardness, drip and boiling loss of hind shank meat increased and palatability decreased, there significant difference were observed only after 9 months. Softness, water holding capacity, L-glutamic acid, oleic acid, and polyunsaturated fatty acid contents increased upon chilling for 4 days after thawing, and there was a significant increase in palatability. The values of VBN and TBA increased markedly upon 6 days of chilling after thawing, and there was a significant decrease in palatability.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.1
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• pp.19-26
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• 2016

This study was performed to evaluate the strength and durability properties of modified epoxy composites with waste tire chip, recycled coarse aggregate, filler and modified epoxy to improve elongation and elasticity of epoxy. Additionally, for comparing to modified epoxy and unsaturated polyester resin as a binder, unsaturated polyester resin composites were developed in the same condition. The mix proportions were determined to satisfy the requirement for the workability and slump according to aggregate size and binder content. Tests for the compressive and flexural strength, freezing and thawing and durability for 20 % sulfuric solution were performed. The compressive and flexural strength of modified epoxy composites were in the range of 34.9~61.6 MPa and 10.2~18.3 MPa at the curing 7 days, respectively. Also, the compressive and flexural strength of unsaturated polyester resin composites were in the range of 44.2~77.8 MPa and 11.3~20.8 MPa at the curing 7 days, respectively. After 300 cycles of freezing and thawing, weight decrease ratio and durability factor of modified epoxy composites were in the range of 0.8~1.9 % and 95~98, respectively. Accordingly, modified epoxy composites will greatly improve the durability of concrete.

• Advances in concrete construction
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• v.11 no.4
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• pp.307-314
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• 2021

Activated hwangtoh (ACT) is a natural resource abundant in South Korea, approximately 15.0% of soil. It is an efficient mineral admixture that has activated pozzolanic properties through high-temperature heating and rapid cooling. The purpose of this study is to improve a curb mixture that can reduce NOx outside and investigate durability performance. To this end, mortar curb specimens were manufactured by replacing OPC with ACT. The ACT substitution ratios of 0.0, 10.0, and 25.0% were considered, and mechanical and durability tests on the curb specimens were conducted at 28 and 91 days of age. Steam curing was carried out for three days for the production of curbs, which was very effective to strength development at early ages. The reduction in strength at early ages could be compensated through this process, and no significant performance degradation was evaluated in the tests on chloride attack, carbonation, and freezing and thawing. The mortar curb with an ACT of 10.0~25.0% replacement ratio exhibited clear NOx reduction through photocatalytic (TiO2) treatment. This is due to the increase in physical absorption through surface absorption and the photocatalyst-containing TiO2 coating. In this study, the reasonable range of the ACT replacement ratio for NOx reduction was quantitatively evaluated through a comprehensive analysis of each test.