• Applied Biological Chemistry
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• v.30 no.4
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• pp.357-363
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• 1987

The transition temperature of respiratory activity of mitochondria isolated from panicles of rice plant was measured with 41 varieties bred in Korea, which had been agronomically classified into five groups based on their relative cold-tolerance; S (strong cold-tolerance), S-M (moderate to strong cold-tolerance), M (moderate cold-tolerance), M-W (moderate to weak cold-tolerance) and W (weak cold-tolerance). The temperature was found to be $11.5{\sim}13.5^{\circ}C$ for group S, $13.5{\sim}16^{\circ}C$ for group S-M, $16{\sim}17^{\circ}C$ for group M, $17{\sim}18^{\circ}C$ for group M-W, and ${\geq}18^{\circ}C$ for group W respectively with a few exceptions of minor deviation, demonstrating a close correlation between the transition temperature and the chilling susceptivity of a variety. This observation supports the suggestion that the transition temperature of respiratory activity of panicles be adopted as a reliable index for grading a rice variety as to its overall cold tolerance. Also studied is on the methodology for measurement of the transition temperature in the aspect of analytical biochemistry. In addition to the usual polarographic method, a spectrophotometric method which is based on the enzymatic assay of membrane-bound cytochrome C oxidase was examined. This enzyme was found previousely and confirmed again in the present work to be a key factor governing the respiratory trantion at least in plant mitochondria. The optical method was turned out to be very successful, although it was a little more complicate and time-consuming than the electrochemical method.

• Journal of Embryo Transfer
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• v.28 no.2
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• pp.113-119
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• 2013

The study focuses on the quality assessment of Black Bengal buck semen preserved at chilled condition. In this in vitro trial, collected semen from Black Bengal bucks was preserved at chilling temperature ($4{\sim}5^{\circ}C$) in tris-glucosecitrate yolk medium of 1:5 ratios for four days. Artificial Vagina (AV) method was utilized to collect semen from buck. General evaluation of semen includes the color, mass activity and density were measured by direct visual examination. However, computer-assisted sperm analysis (CASA) and phase contrast microscopy were used to figure out the motility (%), hyper-activated (HYP) motility (%) and number of abnormal spermatozoa (%) initially, and at every 24 h intervals. The result revealed that spermatozoa preserved at chilling temperature showed significantly (P<0.05) lower motility and HYP motility with the progression of preservation. The number of phenotypically abnormal spermatozoa significantly (P<0.05) increased following preservation. Although significant positive correlation (r=0.945; P<0.05) was existed between % motile and % HYP motile spermatozoa however, the % of morphologically abnormal spermatozoa was negatively correlated with % motile (r=-0.997; P<0.05) and % HYP motile spermatozoa (r=-0.946; P<0.01). Therefore, we concluded that the quality of chilled semen progressively losses its viability and doesn't remain useable after certain period of preservation with respect to its motility and morphology.

• International Journal of Industrial Entomology and Biomaterials
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• v.28 no.2
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• pp.51-57
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• 2014

Bumblebees are important pollinators of crops and wildflowers. The Korean native bumblebee, Bombus ignitus, undergoes one generation per year, and induction of artificial hibernation is essential for year-round rearing of the bumblebee. Keeping queens under cold treatment conditions for several mo is an effective method for terminating their diapause and promoting colony development. In the present study, we investigated how the timing and duration of chilling affect the artificial hibernation of B. ignitus queens. In the timing assessment, cold treatment was instituted at 12 d, 40 d, or 100 d after eclosion under a constant temperature of $5^{\circ}C$ and 80% humidity. The queens that entered cold treatment at 12 d after emergence evidenced the highest survival rates: 86.7% at two mo, 73.3% at three mo, and 46.4% at 4 mo. Survival rates were reduced under storage conditions at 12 d, 40 d, and 100 d after emergence. When queens were subjected to chilling at 8 d, 12 d, or 16 d after eclosion with constant 80% humidity, the queens stored at 12 d after eclosion exhibited the highest survival rates, which were 84.6 at one mo, 25.0% at two mo, and 7.9% at three mo. In regards to the duration of the cold period, the queens that hibernated for at least two mo evidenced optimal colony development rates. The rates of oviposition, colony foundation, and progeny-queen production of queens hibernated for two mo were 60.0%, 30.0%, and 13.3%, respectively. These values were 6.0 to 13.3 times higher than those in the queens that hibernated for 15 d. Therefore, a cold period of at least 2 mo applied 12 d after emergence were found to be the most favorable conditions for diapause break in B. ignitus queens.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2954-2966
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• 1994

The characteristics and good corrosion resistance at room and elevated temperatures led to increasing application of Ti-alloys such as aircraft, jet engine, turbine wheels. In forging of Ti-alloy at high temperature, die chilling and die speed should be carefully controlled because the flow stress of Ti-alloy is sensitive to temperature, strain and strain-rate. In this study, the forging of turbine disk was numerically simulated by the finite element method for hot-die forging process and isothermal forging process, respectively. The effects of the temperature changes, the die speed and the friction factor were examined. Also, local variation of process parameters, such as temperature, strain and strain-rate were traced during the simulation. It was shown that the isothermal forging with low friction condition produced defect-free disk under low forging load. Consequently, the simulational information will help industrial workers develope the forging of Ti-alloys including 'preform design' and 'processing condition design'. It is also expected that the simulation method can be used in CAE of near net-shape forging.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.2
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• pp.148-155
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• 2005

An accurate prediction of blooming date is crucial for many authorities to schedule and organize successful spring flower festivals in Korea. The Korea Meteorological Administration (KMA) has been using regression models combined with a subjective correction by forecasters to issue blooming date forecasts for major cities. Using mean monthly temperature data for February (observed) and March (predicted), they issue blooming date forecasts in late February to early March each year. The method has been proved accurate enough for the purpose of scheduling spring festivals in the relevant cities, but cannot be used in areas where no official climate and phenology data are available. We suggest a thermal time-based two-step phenological model for predicting the blooming dates of spring flowers, which can be applied to any geographic location regardless of data availability. The model consists of two sequential periods: the rest period described by chilling requirement and the forcing period described by heating requirement. It requires daily maximum and minimum temperature as an input and calculates daily chill units until a pre-determined chilling requirement for rest release. After the projected rest release date, it accumulates daily heat units (growing degree days) until a pre- determined heating requirement for flowering. Model parameters were derived from the observed bud-burst and flowering dates of cherry tree (Prunus serrulata var. spontanea) at KMA Seoul station along with daily temperature data for 1923-1950. The model was applied to the 1955-2004 daily temperature data to estimate the cherry blooming dates and the deviations from the observed dates were compared with those predicted by the KMA method. Our model performed better than the KMA method in predicting the cherry blooming dates during the last 50 years (MAE = 2.31 vs. 1.58, RMSE = 2.96 vs. 2.09), showing a strong feasibility of operational application.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.429-444
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• 1991

Cold stress influence plant growth through a wide range of growth characters. Adverse effects of low temperature to plant growth come from results of colligative and complex physiological responses to cold stress. To evaluate more exactly cold tolerance of crop plant, it is needed to observe physiological changes induced by cold stress and to analyze relationships between intraspecific variations in physiological factors related to cold tolerance and the extent of cold tolerance in the field. Therefore, the composition and unsaturation ratio of fatty acids in phospholipid, a constituent of membrane, the transition-temperature in respiratory activity of mitochodria, the chlorophyll fluorescence as a factor related to photosynthesis were investigated in rice plant and data on these factors were compared with the degree of cold tolerance obtained in the field experiment. Also, effects of hardening and Mn++ treatment were evaluated as a method to reduce chilling injuries. The unsaturation ratio of fatty acids, whether rice plants were grown in a natural condition or under the chilling stress, was higher in the cold- tolerant varieties and was significantly correlated with the degree of cold tolerance (1-9) observed in the field experiment. And it was also increased by chilling treatment or hardening treatment, due to a reduction in palmitic acid content and an increase in linolenic acid content. The transition-temperature of respiratory activity of mitochodria isolated from etiolated rice seedlings ($25^{\circ}C$, two week-grown in the dark), was correlated with the degree of cold tolerance in the field, cold -tolerant varieties showing a lower transition-temperature. It was not influenced by growth stages. The intensity of chlorophyll fluorescence was highly correlated with the degree of cold tolerance, cold-tolerant varieties having a higher fluorescence intensity. By foliar application of Mn, the transition-temperature of respiratory activity was lowered as much as 0-2$^{\circ}C$ in all tested varieties. Soil application of Mn induced more significant effect in cold-susceptible varieties with a possibility of reducing chilling injuries. On the whole, there were high correlationships among the degree of cold tolerance, the unsaturation ratio of fatty acids in phospholipid, the transition- temperature of respiratory activity and chlorophyll fluorescence except for a few varieties. The transition- temperature of respiratory activity appeared to be negatively correlated with the unsaturation ratio of fatty acids. and the chlorophyll fluorescence to be positively correlated with the unsaturation ratio. This implies that these physical and physiological factors were very closely related to cold tolerance and can be used as an effective index of the evaluation of cold tolerance of crop plant. But other factors as well as three factors discussed above are needed to be considered colligatively and altogether with a systematic analysis for the more exact evaluation of cold tolerance. in rice cultivars. in rice cultivars.

• Journal of Practical Agriculture & Fisheries Research
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• v.24 no.1
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• pp.29-35
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• 2022

This study was conducted to investigate the seed storage method and seed germination characteristics of Synurus deltoides (Ait.) Nakai, a kind of wild vegetables. Several parameters affecting seed germination, such as germination temperature, chilling duration, imbibition duration, and storage method were evaluated. The seed germination of Synurus deltoides showed the highest germination rate (GR), promptness index (PI), germination performance index (GPI), mean daily germination (MDG) at 25℃. This implies that the optimum germination temperature was 25℃. And also, Seeds stored at -4℃, after 150 days showed relatively high germination rate about 98%. Therefore, The optimum germination temperature of Synurus deltoides was 25℃ and to increase the germination rate over 98% of Synurus deltoides, cold-wet storage 20 days treatments at 4℃ were effective in the improvement of seed germination.

• Korean Journal of Poultry Science
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• v.23 no.4
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• pp.193-201
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• 1996

This experiment was carried out to find out the effect of packing methods on physico-chemical properties of breast and thigh meats in chicken, which was dried by air spray chilling method. The chicken carcass was cut into breast and thigh muscles, which were either vacuum packed or atmosphere packed, and stored at -2O˚C for 1, 4, 8, 12 and 16 wk after quick freezing at -45˚C for 35 min. The pH values of atmosphere-packed breast meat and vacuum-packed breast meat after one wk of storage were higher than those of atmosphere-packed thigh meat and vacuum-packed thigh meat(P< .05). The pH values increased as storage period extended, but no significant difference was detected between two packing method(vacuum vs. atmosphere). Total moisture contents of breast meats after one wk of storage were higher than those of thigh meats. The total moisture contents decreased slowly as storage period extended, but no significant difference was detected between two packing method(vacuum vs. atmosphere). The shear force value of thigh meat was higher than that of breast meat. The shear force values of both meats decreased as storage period extended, regardless of packing method. The water soluble protein extractability of thigh meats was higher than that of breast meat, and the water soluble protein extractability of all treatments decreased until 8 wk after storage, but increased gradually after 8 wk of storage period. The salt soluble protein extractability of breast meat was higher than that of thigh meat, and the salt soluble protein extractability of all treatments decreased as storage period extended. With regard to the packing method, the vacuum packing showed higher value than that of atmosphere packing method until 8 wk of storage. Total lipid contents of atmosphere- and vacuum-packed thigh meats at 1 wk of storage were higher than those of breast meats, and the total lipid contents of all of treatments decreased as storage period extended. However, no significant difference was detected between two packing methods. The fatty acid contents of breast and thigh meats were in order of o1eic(33,5~42.4), palmitic(19.7~30.8) and linoleic acid(10.8~17.4).

• Food Science of Animal Resources
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• v.25 no.1
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• pp.1-6
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• 2005

To evaluate the microbiological quality of pork carcasses at different slaughtering process in large and small scale slaughtering houses, swabbing method was used to analyze microorganisms on the surface of pork belly in each process of before evisceration, after evisceration, before final wash, after final wash and in chilling. In autumn time, large scale slaughterhouse showed lower incidence of aerobic microorganisms (10²∼10³ CFU/㎠) than those of small scale slaughterhouse (10⁴∼10/sup 5/ CFU/㎠) during all processing lines. Samples from cold room of large scale slaughterhouse showed lower incidence of aerobic cells (10² CFU/㎠) than small scale slaughterhouse (10⁴ CFU/㎠). In winter and spring time, large scale slaughterhouse showed lower incidence of aerobic microorganisms than those of small scale slaughterhouse during the slaughtering process of before evisceration, after evisceration and before final wash, except spring samples from before final wash and chilling at cold room storage in spring time. After final wash, different sampling place of carcass such as belly, ham, jowl showed the different washing effect depending on the small and large scale slaughterhouse. After final wash, ham and belly had lower aerobic cell counts, but jowl had higher aerobic cell counts than each site before final wash.

• Journal of the Korean Society of Food Science and Nutrition
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• v.6 no.1
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• pp.1-8
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• 1977

The sample persimmons were obtained from the of Yung-am Kun, Korea on October 24, and November 9, 1973. These persimmons were kept at room temperature overnight, then packed and stored on the following day at $0^{\circ}C$ and $85{\sim}100%$ humidity. Seven experimental items were studied : 1. control, 2. packing with excelsior in wooden boxes, 3. packing with rice hull in wooden boxes, 4. packing in bags of 0.03 mm polyethylene membrane, 5. packing in bags of 0.06 mm polyethylene membrane, 6. packing in bags of 0.08 mm polyethylene membrane, 7. packing in sealed desiccators. The dimension of polyethylene bags were $14{\times}28cm$ and three persimmons were packing in each bag. The results are as follows: 1. The persimmons both in polyethylene bags and in desiccators lost only 1 % or less of weight, while in control (1) packing with excelsior (2) or with rice hull (3) the loss was 6-7 % in weight after $2{\sim}3$ months. The persimmons became visibly shriveled and spongy-like in it's texture when it lost 5 % of weight. 2. Carbon dioxide content within the polyethylene bags and desiccators rapidly increased during the early storage period, and reached 5 % (in 0.03 mm polyethylene bags) to 50 % or more (in desiccator) after 1 month. In the polyethylene bags of 0.08 mm and desiccator, the carbon dioxide accumulated to a dangerous level and the persimmon showed physiological damage in a longer storage period. 3. The advance of after-ripening and deterioration of persimmon sealed in the polyethylene bags was slower than that in open bags when moved out to room temperature from the chilling and the polyethylene bags of 0.06 mm retarded the after-ripening most effectively. 4. On the basis of these results, a temperature of $0^{\circ}C$, relative humidity of almost $85{\sim}100%$ and combinations of 5 % oxygen and $5{\sim}8%$ carbon dioxide seem to be the optimum condition for the storage of persimmon (Teabong-Si). The most successful method of storing was to pack them in polyethylene bags of 0.06 mm and then to store them at $0^{\circ}C$.