• Integrative Medicine Research
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• 제6권1호
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• pp.12-18
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• 2017

Cryopreservation is a process that preserves organelles, cells, tissues, or any other biological constructs by cooling the samples to very low temperatures. The responses of living cells to ice formation are of theoretical interest and practical relevance. Stem cells and other viable tissues, which have great potential for use in basic research as well as for many medical applications, cannot be stored with simple cooling or freezing for a long time because ice crystal formation, osmotic shock, and membrane damage during freezing and thawing will cause cell death. The successful cryopreservation of cells and tissues has been gradually increasing in recent years, with the use of cryoprotective agents and temperature control equipment. Continuous understanding of the physical and chemical properties that occur in the freezing and thawing cycle will be necessary for the successful cryopreservation of cells or tissues and their clinical applications. In this review, we briefly address representative cryopreservation processes, such as slow freezing and vitrification, and the available cryoprotective agents. In addition, some adverse effects of cryopreservation are mentioned.

• 대한설비공학회지:설비저널
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• 제13권4호
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• pp.223-229
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• 1984

Experiments were performed for freezing of an initially superheated or nonsuperheated liquid phase in a cooled vertical tube. The liquid was placed in a copper tube whose surface maintained a uniform temperature during the data run and the freezing occurred in a copper tube. The phase change medium was n-odtadecane, a paraffin which freezes at about $61^{\circ}C$. Measurements were made which yielded information about the time dependence of the freezing front, of the amount of frozen mass, and of the various energy components extracted from the tube. The time-wise decay of the initial liquid superheat was also measured. Initial superheat of the liquid tends to moderately diminish the rozen mass and associated latent energy extraction at small times but has lit tie effect on these quantities at large tiems. Natural convection in the liquid Plays a modest role only at small times and disappears when the superheat decay to zero. Although the latent energy constitutes the largest contributor to the total extracted energy, the sensible energy components can make a significant contribution, especially at large tube wall subcoolings, large initial liquid superheating and short freezing time.

• 설비공학논문집
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• 제17권7호
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• pp.629-634
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• 2005

This paper performed to predict vertical temperature distribution and air flow near cold heat source in the mass merchandising store. At the height of 150 cm, the vertical air temperature difference between the results of CFD and of measurement field showed $10\%$ near the refrigeration zone and $8.8\%$ near the freezing zone. Therefore, it regarded as appropriate for the using CFD to investigate airflow near the heat sources. The 3 kinds of CFD model were divided by the disposition of diffuser/exhaust and diffuser air temperature. At the refrigeration and freezing zone in the Model 2 and 3, the temperature difference between the front and the back of human model were showed $6.8^{\circ}C\;and\;3.9^{\circ}C$ with diffuser air temperature $17^{\circ}C$ and were showed $6.8^{\circ}C$ and $4^{\circ}C$ with diffuser air temperature $19^{\circ}C$.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.807-812
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• 2001

This study is peformed for checking the limitation and application of each curing/heating methods on cold-weathering mat foundation construction, considering temperature control, early strength security and temperature declination range limit, by means of concrete material properties and thermal analysis technique that were published previously. In the result of this analysis, we checked the open air temperature and mat depth that are possible to apply each curing/heating methods on cold-weathering construction and found curing/heating time of each methods that is able to prevent early aged freezing damage and thermal crack

• 대한가정학회지
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• 제19권1호
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• pp.39-45
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• 1981

The fishes that are mostly used in our homes such as Pacific Mackeral, hair Tail and Alaska Pollack were devided into Freezing group, Refrigerating group and Room temperature group according to storage temperature. TVB-N, TMA-N, TMA-O and pp.H. were measured in natural state, after water washing and 3% NaCl-water washing. The results are as follows: 1. Regardless of the kinds of fishes, TVB-N in room temperature showed that rottenness first appeared after 5~8 hours in raw state, 6~12 hours in water washing, and 8~12 hours in 3% NaCl-water washing. 2. Regardless of freezing and refrigeration, Pacific Mackeral became rotten after 14 days in raw state, 14~17 days in water washing and 17 days in 3% NaCl water washing. Alaska Pollack and Hair Tail showed rottenness after 8 days in raw state, 11 days in water and 3% NaCl water washing. 3. Even in hot summer days, freshness could be preserved for 10 days if fishes were freezed ($-20^{\circ}C$) or refrigerated (4~$8^{\circ}C$) after bowel excluded, washed in NaCl water and enveloped in poly-ethylene bag.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.199-204
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• 2000

When fresh concrete is exposed to low temperature, the concrete may suffer from the frost damage at early ages and the strength development may be delayed. To solve such problems of cold weather concreting, admixtures called agent for enduring cold climate are developed to prevent the fresh concrete from being frozen at early ages In this study, the experiments are carried out on several kinds of agent for enduring cold climate to present their performance. According to experimental results, most kinds of agent for enduring cold climate show the satisfactory properties of decreasing the freezing point and acceleating the cement hydration in low temperature environment, which is available for placing concrete in spite of cold weather.

• 물과 미래
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• 제6권1호
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• pp.13-18
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• 1973

If the temperature of free water drops below the freezing point the water turns into ice and its volume increases. Analyzing of the results in test, it is hoped that these is broadly used in engineering plan. The compressive strength of frozen soils and the unconfined compressive strength of the ice. The creep strength depends on factors including creep ratio, time, strain and temperature. For a linear decreases in temperature, strength predicts an exponential increasing. The relationships between dry unit weight and compressive strength, water content and freezing with compacted soil samples, have been analyzed to understand the strength of frozen soil. Therefore, it is thankful that the results of analsis shall find useful application as a framework for generalizing experimental information as well as a basis for solving various frozen soil mechanics problems.

• 동력기계공학회지
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• 제14권3호
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• pp.19-24
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• 2010

The purpose of this study is to develop a snow melting system using the pulsating heat pipe(PHP). The experimental apparatus is consisted of a PHP, a concrete structure, a constant water thermostatic bath and a flowmeter. The experiment was performed at the outdoor air temperature of $-8^{\circ}C$ and inlet temperature of hot water of $75^{\circ}C$. PHP is the closed and non-loop type heat exchanger which is charging R-410A as an operating fluid. As experimental results, the temperature profile of vertical and horizontal orientation of concrete structure was measured with operating time. The heat flux of the snow melting was required more than 300 $W/m^2$. We confirmed that the snow melting system using the PHP was useful for anti-freezing road.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1995년도 춘계학술발표회 초록집
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• pp.223-229
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• 1995

Heat transfer phenomena during freezing process of the water in a vertical cylinder were experimentally studied. Purified water was inserted into the vertical cylinder Experiment was performed with two conditions ; the inlet temperature of the working fluid was maintained to be -1$0^{\circ}C$ and the direction of the working fluid was to be upward or downward. Both the mean temperature of the liquid and temperature difference of cylinder tube wall in the upward were lower than those in the downward. In addition, shape of ice layer in the upward was more uniform than that in the downward. Finally, time-varying total heat energy stored in the water in the upward was higher than that in the downward.

• Asian-Australasian Journal of Animal Sciences
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• 제15권11호
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• pp.1553-1558
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• 2002

This study was carried out to obtain informations regarding the effect of N-acetyl-D-glucosamine in the LEY (lactoseegg yolk) diluent according to incubation time in 5 ml maxi-straw and the effects of freezing rate, thawing temperature and thawing time in the LEN (lactose-egg yolk and N-acetyl-D-glucosamine) diluent on acrosome morphology and motility of frozen-thawed boar sperm. The study showed that the LEN diluent was higher post-thaw NAR (normal apical ridge) acrosome than the LEY diluent for 0.5 h incubation at 37$^{\circ}C$. However, there were no differences between the LEN and LEY diluents on post-thaw sperm motility according to incubation time. The straws frozen from 5.0 cm (20$^{\circ}C$/min) to 17.0 cm (1$^{\circ}C$/min) above the liquid nitrogen surface did not show any significant differences on post-thaw sperm motility. However, the straws frozen above 5.0 cm from the liquid nitrogen surface were higher NAR acrosome than those frozen above 17.0 cm. The post-thaw percentages of motile sperm and NAR acrosome were significantly higher (p<0.05) for the maxi-straws submerged for 40 or 45 sec in a 52$^{\circ}C$ water bath than for 30, 35, 50 or 55 sec. The mean sample temperatures of maxi-straws after 40 or 45 sec submersion were 20.7 or 26.4$^{\circ}C$. In conclusion, the sample temperature of the thawed semen was very important for post-thaw sperm survival in the LEN diluent of 5 ml maxi-straw. When the temperature of the thawed semen was 20.7$^{\circ}C$, the percentages of motile sperm and NAR acrosome were highest.