• Journal of Chest Surgery
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• v.39 no.7 s.264
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• pp.520-526
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• 2006

Background: The clinical application of cryosurgery the management of lung cancer is limited because the response of lung at low temperature is not well understood. The purpose of this study is to investigate the response of the pulmonary tissue at extreme low temperature. Material and Method: After general anesthesia the lungs of twelve Mongrel dogs were exposed through the fifth intercostal space. Cryosurgical probe (Galil Medical, Israel) with diameter 2.4 mm were placed into the lung 20 mm deep and four thermosensors (T1-4) were inserted at 5 mm intervals from the cryoprobe. The animals were divided into group A (n=8) and group B (n=4). In group A the temperature of the cryoprobe was decreased to $-120^{\circ}C$ and maintained for 20 minutes. After 5 minutes of thawing this freezing cycle was repeated. In group B same freezing temperature was maintained for 40 minutes continuously without thawing. The lungs were removed for microscopic examination on f day after the cryosurgery. In four dogs of the group A the lung was removed 7 days after the cryosurgery to examine the delayed changes of the cryoinjured tissue, Result: In group A the temperatures of T1 and T2 were decreased to the $4.1{\pm}11^{\circ}C\;and\;31{\pm}5^{\circ}C$ respectively in first freezing cycle. During the second freezing period the temperatures of the thermosensors were decreased lower than the temperature during the first freezing time: $T1\;-56.4{\pm}9.7^{\circ}C,\;T2\;-18.4{\pm}14.2^{\circ}C,\;T3\;18.5{\pm}9.4^{\circ}C\;and\;T4\;35.9{\pm}2.9^{\circ}C$. Comparing the temperature-distance graph of the first cycle to that of the second cycle revealed the changes of temperature-distance relationship from curve to linear. In group B the temperatures of thermosensors were decreased and maintained throughout the 40 minutes of freezing. On light microscopy, hemorrhagic infarctions of diameter $18.6{\pm}6.4mm$ were found in group A. The infarction size was $14{\pm}3mm$ in group B. No viable cell was found within the infarction area. Conclusion: The conductivity of the lung is changed during the thawing period resulting further decrease in temperature of the lung tissue during the second freezing cycle and expanding the area of cell destruction.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.397-400
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• 2008

MgO powder-mixed concrete, expanded at the lower temperature around $850{\sim}1000$ degree celcius, might have long-term expansibility, which could remunerate for the contraction of concrete with delayed expansion, and through the process, the crack resistance of mass concrete might be improved. Currently used expandable concrete additive has three different types : CSA, CaO and MgO. In this study, therefore, such tests as carbonation, chloride diffusivity, freezing-thawing resistance and sulfate resistance after 56 days' curing were implemented and compared the results with the concrete with no MgO mixed to evaluate the durability of 5% MgO-mixed concrete after longer period of time. The degree of hydration for the MgO-mixed cement paste was analyzed after 1 day, 3 days, 7 days, 28 days, and 56 days using SEM, XRD, DSC.

• Korean Journal of Food Science and Technology
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• v.10 no.2
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• pp.203-208
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• 1978

A study was made on the changes in Acid Value (AV) and Peroxide Value (POV) of the Mackerel ordinary muscle during low temperature storage. Three different samples were used-natural (control), ascorbic acid (As. A)-added and NaCl-added. The samples were stored at the temperature of $-15^{\circ}C$ during 75days immediately after quick freezing at $-23^{\circ}C$ The change in the amount of fatty acids was also measured by means of GLC method. 1. In comparison with the control, the As. A -added showed lower AV and POV, whereas the Nacl-added gave higher values. 2. Among the various fatty acids, which are constituents of the fish lipids, the amount of palmitic acid (16:0), stearic acid (18:0), and oleic acid (18:1) had been increased during the storage, while there had been steady decrease in the amounts of unsaturated fatty acid such as linolenic acid (18:3), arachidonic acid (20:4), clupanodonic acid (22:5), and docosahexaenoic acid (22:6). 3. For the first 30 days after freezing, the decreasing rates of the amounts of docosahexaenoic acid in three samples of the As. A-added, the control, and the NaCl-added-were 7%, 14% and 36% respectively. However, after 45 days these samples showed the same decreasing rates of more than 57 percent.

• Journal of Microbiology and Biotechnology
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• v.6 no.2
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• pp.128-131
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• 1996

Lactobacillus acidophilus KFRI 233 (of human origin) exhibited a high tolerance to bile. The maximum cell yield was 6.6${\time}10^9 CFU$ per gram of whey in a 5.0% whey medium. Cell growth was improved with the addition of 0.5% thiotone and 0.25% calcium carbonate. Cell growth reached a maximum level of 5.4${\times}10^8$ CFU/ml at 20 h. Eighty-nine percent of the viable cells in the centrifuged concentrate survived freezing at $-70^{\circ}C$ and this frozen concentrate showed no reduction in the viable cell count after 30 days at $-70^{\circ}C$. Eight percent of the viable cells survived freeze-drying after the addition of 1 g/l sodium carbonate before harvesting by centrifuging and this freeze-dried concentrate showed only a slight reduction in the viable cell count after 30 days at $4^{\circ}C$.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.2
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• pp.3778-3783
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• 1975

The objective of this study is to determine an appropriate cement of soil-cement in which silty soil of salty tidal flat with low plasticity was used. Physical, chemical and mechanical tests were conducted to find out the standard properties of the soil to be used. Various cement contents used in this test were 8%, 10%, 12%, and 14%, and the compressive strength was tested after 7 days and 28 days of standard curing in the above each cement content respectively. The results obtaind are summarized as follows. 1. As the cement content was increased from 8% to 14%, Maximum dry density (M.D.D.) and optimum moisture content (O.M.C.) were not changed remarkably. 2. Density of soil-cement was directly proportional to cement content and inversely proportional to water content. 3. OMC was generally decreased in proportion to the increase of cement content. 4. Compressive stranth was directly proportional to centent and inversely proportional to water content. 5. In freezing and thawing test, maximum loss of 10% in the total Weight was found on the 8% cement mixture. and This loss was rapidly decreased to 2% when the Cement content of the mixture was more than 10%.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.203-204
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• 2016

In this research, it used cement power and reduction slag, which generates high hydration heat in hydration reation without heat cure below -5℃ degree. Purpose of final research is preventing freezing and thawing by making the compressive strength 5MPa in 3days below zero temperature due to own heat of concrete. and it is the result of physical characteristic and thermal property evaluation of reduction slag. Because reduction sag generates high hydration heat, compressive strength development is excellent. By generating highly Hydration heat by C₁₂A₇ and C₃A in reduction slag, compressive strength is developed in low temperature. In case of displacing only reduction slag without SO₃, it is indicated that quick-setting occurs by shortage of SO₃. For preventing quick-setting, gypsum is used essentially. According to this research result, in case of using reduction slag and gypsum as a ternary system, Compressive strength developed 5MPa in 3days below zero temperature. It is identified to prevent early frost damage of concrete below zero temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.75-77
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• 2013

In this study, the characteristics of temperature history was evaluated for three hot wires with different capacity installed in slab concrete which are relatively thin. Results can be summarized as follows. First, for the case of material using 5W hot wire, all decreased to below zero at or around 24 hours. Similarly, the material using 20W hot wire decreased to 2℃ below zero at or around 80 hours but satisfied the accumulative temperature of 45° D·D at 7 days of material age. On the other hand, the case of 30W hot wire, the biggest capacity, showed the high temperature history of 5℃ in average at all areas except the corners. Thus, the target accumulative temperature was secured at or around the 3 days of material age. Considering the above, the initial damage by freezing can be prevented only if 20W or higher hot wires are used for the slabs at -10℃ of extremely low temperature environment.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.3
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• pp.46-58
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• 1984

This study was carried out to investigate the compressive strength and the other effects varying to seasons and curing days on the wet curing conditions of the plain concrete. The results obtained are summarized as follows; 1. The longer the wet curing days and the higher the temperature, the greater the compressive strength was expected. 2.。$_2$8, compressive strength of concrete at 28 days under the dry curing conditions showed a range in 64-76% of that under the wet curing conditions. 3. The seasonal variations in the compressive strength under the wet curing showed in order of summer>spring=autumn>winter, and that under the dry curing were in order of spring ≒autumn> summer> winter. 4. In order to obtain 90% of the design compressive strength, 7 days in spring or autumn and 2 weeks of the wet curing in summer were required. 5. The compressive strength of concrete under the wet curing by using wet straw bag cover was almost the same as that of water curing method. 6. Under the wet curing conditions, the higher the temperature, the greater the effect of the curing of concrete was obtained, however, the compressive strength of concrete was decreased under relatively higher (over 15$^{\circ}$ C) and lower temperature (below 4$^{\circ}$C). 7. Freezing damage was occured when temperature was below 0$^{\circ}$ C and humidity was relatively high. 8. A considerable differnce between estimation of $^{\circ}$$_2$8 from $^{\circ}$7 and measured one was appeared in case of the dry curing conditions. Oregon formula was appeared to be acceptable under the wet curing conditions. 9. In relationship between $^{\circ}$$_2$8 and $^{\circ}$7~, $^{\circ}$28=1. 52 $^{\circ}$7 under the wet curing conditions except winter season, and $^{\circ}$$_2$8 =(1.39-1, 48)$^{\circ}$7 under the dry curing conditions were shown.

• Korean Journal of Animal Reproduction
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• v.23 no.1
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• pp.75-84
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• 1999

This study assessed development in vitro of pronuclear(PN) stage embryos cryopreserved by the method of either vitrification or slow freezing, by using of different cryoprotectants, and equilibration and cooling rate, in rabbit. Ethyleneglycol- ficoll- sucrose(EFS) or ethyleneglycol- polyvinylpyrrolidone - galactose- (EPG-I) for vitrification, and EPG- II for slow freezing as cryoprotectant were used. The pronuclear embryos were exposed to EFS for 0 to 5 min and diluted with D-PBS and/or pre-dilution with 0.5 M sucrose. To examine the viability of frozen-thawed embryos, PN embryos were co-cultured with bovine oviductal epitherial cell(BOEC) for 5 days to hatching blastocyst stage in 39 $^{\circ}C$ 5% $CO_2$incubator. The results obtained were as follows: The dilution with 0.5 M sucrose and D-PBS after the exposure to EFS for 1.0 min resulted in no significant(P＜0.05) decrease in the development of PN embryos to hatching blastocyst(72.0%), compared with controls. The development of PN embryos cryopreserved to hatching blastocyst was not significantly (P＜0.05) different between EFS for 1.0 min(72.0%), EPG-I for 1.0 min(72.0%) and EPG-II for 30 min(66. 7%). The post-thaw development of PN embryos to hatching blastocyst was similarly very low as 6.1% and 11.5% in vitrification with EFS and slow freezing with EPG-II, respectively. The incidence of post-thaw zona-crack in PN embryos cryopreserved by slow freezing with plunging to liquid nitrogen at －35$^{\circ}C$ was signicantly(P＜0.05) higher(25.0%), compared with －85$^{\circ}C$ (1.9%). These results indicated that the rabbit PN embryos could be cryopreserved with either vitrification or slow freezing procedure, and frozen PN embryos could be successfully developed in vitro to haching blastocyst. but the post-thaw development of cryopreserved PN embryos was still very low under the present conditions.

• Food Science and Preservation
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• v.23 no.7
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• pp.931-938
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• 2016

To evaluate the effect of freezing temperature on quality characteristics of dried persimmons, dried persimmons were frozen at $-50^{\circ}C$ (quick frozen, QF) and $-20^{\circ}C$ (slow frozen, SF) for 24 hr. Frozen persimmons were then stored at -20, -10, 0 and $10^{\circ}C$ for 80 days. Total free sugar content of SF persimmons was higher than those of QF in the $+10^{\circ}C$ and $-20^{\circ}C$ stored samples. Except for samples stored at $10^{\circ}C$, the CIE $L^*$ values for QF persimmons were higher than those for SF persimmons. For samples stored at $10^{\circ}C$ and $0^{\circ}C$, the CIE $a^*$ and $b^*$ values of SF samples were higher than those for QF samples. The texture of frozen dried persimmons was investigated to determine springiness, chewiness and hardness. Chewiness and hardness of samples held at $0^{\circ}C$ were higher in SF than in QF persimmons. However, when stored at $-10^{\circ}C$, chewiness and hardness were higher in QF than in SF samples. Springiness results were similar among the QF and SF persimmons held at different storage temperatures. For all storage temperatures, QF persimmons had a high soluble tannin content. All of the sample, the average soluble tannin contents of QF is 236.09 mg%. On the other hands, those of SF is 226.87 mg%. The results indicate that freezing rate and holding temperatures have significant effects on dried persimmon texture, soluble tannin level, and free sugar content. Further studies that include sensory evaluations are needed to determine the optimum freezing rate and holding temperature for dried persimmons.