• Journal of the Korea institute for structural maintenance and inspection
• /
• v.19 no.4
• /
• pp.67-74
• /
• 2015

In this study, effects of micropores on the freezing-thawing resistance of high volume slag concrete are reviewed. Concrete was made with slag which contains the ground granulated blast furnace slag(GGBS) and the pig iron preliminary treatment slag(PS) by replacing 0, 40, 70 %, then compressive strength, freezing-thawing resistance, micropores were reviewed. Also, specified design strength, target air contents were set. Deterioration was induced by using 14-day-age specimen which has low compressive strength for evaluating deterioration by freeze-thawing action. As results of the experiment, despite of specified design strength which has been set similarly and ensured target air contents, the pore size distribution of the concrete showed different results. Micropores in GGBS70 specimen have small amount of water which is likely to freeze because there is small amount of pore volume of 10~100 nm size at 0 cycle which has not been influenced by freezing-thawing. For these reasons, it was confirmed that the freezing-thawing resistance performance of GGBS70 is significantly superior than other specimens because relatively small expansion pressure is generated compared to the other specimens.

• The Korean Journal of Malacology
• /
• v.24 no.1
• /
• pp.51-57
• /
• 2008

With the purpose to estimate the possibility of short-term storage and cryopreservation for sperm of Charonia sauliae, which is a potential preparation for its artificial reproduction and further research, in this study, protocols for short-term storage and cryopreservation of trumpet shell sperm was optimized. The effects of different immobilizing solutions, dilution ratios were estimated for short-term storage. And the effects of different cryoprotectant extenders and freezing rates were estimated for cryopreservation in terms of motility and survival of sperm. The results indicated that the artificial sea water of 350 mOsmol/kg is a better immobilizing solution and sperm which was diluted at a ratio of 1:1 (v/v) had higher motility and survival rate during short-term storage. The effect of 5% dimethyl sulfoxide was significantly better than those of other cryoprotectant extenders. And a freezing rate of $-20^{\circ}C\;min^{-1}$ showed better effect than other freezing rates. In conclusion, this study optimized some key factors of the short-term and cryopreservation of C. sauliae sperm, which can provide valuable data for germ-plasm conservation and artificial propagation of C. sauliae.

• Journal of Embryo Transfer
• /
• v.7 no.1
• /
• pp.13-19
• /
• 1992

This study were carried out to investigate the effective concentration of cryoprotective agents and sucrose by one-step straw method, and to determine the optimum thawing temperature and equilibration time of frozen porcine embryos. The porcine embryos foflowing dehydration by cryoprotective agents and a various concentration of sucrose were directly plunged into liquid nitrogen and thawed in 3$0^{\circ}C$ water. Survival rate was defined by FDA test. The results are sunnnarized as follows : 1. The survival rates of porcine embryos after ultrarapid frozen4hawing in the freezing medium with a various concentration of glycerol, DMSO and propanediol added 0.25M sucrose were higher survival rate than those of sucrose concentration of 0.50M. 2. The survival rates of porcine embryos after ultrarapid ftozen4hawing in the freezing medium added 0.25M and 0.SOM sucrose were higher survival rate than those of sucrose concentration of 0.75M and 1.00M. 3. The temperature thawed at 2$0^{\circ}C$ and 3$0^{\circ}C$ resulted in a significantly higher embryos survival rate after 72 hrs in culture than did at 35$^{\circ}C$. 4. The equilibration time on the survival rate of porcine embryos was attained after short period of time(2.5~5 min.) in the freezing medium higher than long period of time(10~20 min.).

• Korean Journal of Animal Reproduction
• /
• v.18 no.1
• /
• pp.15-23
• /
• 1994

This study was carried out to investigate the effects of concentration, kinds of cryoprotectants, equilibration time, optimum thawing temperature on the survival rate of rapidly frozen porcine embryos. The porcine embryos following dehydration by cryoprotectants containing sucrose were directly plunged into liquid nitrogen and thawed in 30, 35 or 37$^{\circ}C$ water bath, Survival rate was defined as development rate on in vitro culture or FDA-test. The results are summarized as follows : 1. The high survival rate of porcine frozen embryos after rapidly thawed in freezing medium was attained 2.0M DMSO, 2.0M glycerol, 2.0M propanediol, 1.5M ethyleneglycol. 2. The high survival rate of porcine frozen embryos after rapidly thawed in freezing medium was obtained using single cryoprotectant(16.6~40.0%) than mixed cryoprotectants(12.5~33.3%). 3. The eqilibration time on the survival rate of rapidly thawed porcine frozen embryos was attained after short period of time(15.0~33.3%) in the freezing medium higher than long period of time(9.10~30.0%). 4. The thawing temperature on the survival rate of rapidly thawed porcine frozen embryos was attained at 3$0^{\circ}C$ of thawing temperature(33.3~40.6%) in the freezing medium higher than 25 or 37$^{\circ}C$ of thawing temperature.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.22 no.3
• /
• pp.115-120
• /
• 1989

Physicochemical changes were investigated during repeated freezing and thawing processes using fish meat paste of alaska pollack (Theragra chalcogramma). During repeated thawing process, the solubility of myofibrillar protein, $Ca^{++}-ATPase$ activity, water holding capacity (WHC), electrophoretic patterns and rheological properties were evaluated at various thawing temperatures. Solubility of myofibrillar protein and $Ca^{++}-ATPase$ activity were decreased with increasing thawing temperatures. Thawing temperatures and the frequency of freezing and thawing processes did not affect WHC significantly. Upon repeated freezing and thawing cycles, electrophoretic patterns showed that only the amount of myosin heavy chain was decreased, whereas the amount of actin remained constant. Young's modulus for viscoelasticity of fish meat pastes increased with increasing thawing temperatures and the value showed maximum at third cycle and decreased thereafter.

• Food Science and Biotechnology
• /
• v.15 no.6
• /
• pp.986-989
• /
• 2006

Sweet potato starch noodles prepared without freezing exhibited higher cooking loss and water uptake during cooking and usually resulted in noodles with a softer and stickier texture compared to commercial sweet potato starch noodles manufactured using a freezing process. By utilizing the starches of different plant sources (potato, cowpea, and sago in an equivalent mixture with sweet potato starch), however, the cooking properties and texture of the starch noodles could be improved. Among the starches tested, cowpea starch was most effective in providing cooking and textural properties similar to those of commercial noodles. As an alternative approach, the addition of a minor amount (0.1 % based on total solid weight) of various gums (xanthan, gellan, locust bean gum, curdlan, and carboxymethyl cellulose) was also examined. The addition of curdlan to noodles was effective in increasing the gumminess and hardness, and reducing the stickiness of noodles. Utilizing different starches and gums can improve the overall texture and quality of sweet potato starch noodles produced without freezing.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.44 no.4
• /
• pp.362-369
• /
• 2008

The snow melting system by electric heating wires which is adopted in this research is a part of road facilities to keep surface temperature of the road higher than freezing point of water for melting the snow accumulated on it. The electric heating wires are buried under paved road at a certain depth and operated automatically and manually. Design theory, amount of heating, and installation standard vary according to economic situation, weather condition, installation place and each country applying the system. A main purpose of this study is figuring out the appropriate range of required heat capacity and installation depth and pitch for solving snowdrifts and freezing problems with minimum electric power consumption. This study was performed under the ambient air temperature($-2^{\circ}C$, $-5^{\circ}C$), the pitches of the electric heating wires(200 mm, 300 mm), heating value($250\;W/m^2$, $300\;W/m^2$, $350\;W/m^2$).

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.17 no.4
• /
• pp.451-458
• /
• 2004

The study was focused on the development of computational scheme in three dimensional configurations by applying effective heat capacity model to the numerical procedure in order to predict the temperature profiles of a buried pipeline and the frozen penetration depth(FPD) of a freezing soil medium. To realize this, the investigator conducted the unsteady state heat transfer analysis, using the commercial code ABAQUS, for the freezing granite soil medium including a pipeline in a closed system. The proposed model took into consideration the phase change effect of in situ pore water in the frozen fringe. The comparison of results obtained by the proposed model and the actual performances was valuable in establishing a level of confidence in the application of introduced theory.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2015.11a
• /
• pp.151-152
• /
• 2015

Concrete parking slab is often deteriorated severely after winter season because of concrete's freezing and thawing phenomenon. In this study, some methods to improve resistance against freezing-thawing is experimentally tested.: 1) concrete strength, 2) air content in concrete, 3) saw-cut effect and finish material. After experiment, in case of no finishes, 24MPa concrete with 4% air content is tested best result in terms of relative elastics modulus among testes ones. In case of concrete with finishes, all specimens are improved regardless of finishes compared to concrete with no finishes. Improvement degree compared to no finish is as follows : Polyurea > Resin-mortar > hardener and the number of improvement degree is 5, 4, 2% respectively. Further work is required considering construction site condition such as gaining water on surface and remicon in order to reflect site condition.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2008.11a
• /
• pp.227-233
• /
• 2008

Porous concrete has large continuous voids of 20-30 % by volume, and this concrete is attractive as environmental material in Japan i.e. permeable road pavement, river bank protection with vegetation and green roof system which influence thermal environment. It is necessary to confirm the frost resistance when constructing porous concrete structure in cold region. However applicable test method and evaluation criterion of porous concrete has not defined yet. Therefore, the object of this study is to investigate the frost resistance of porous concrete and this investigation attempts to address this concern by comparing 4 kinds of specified freezing and thawing tests methods (JIS A1148 procedure A/B and RILEM CIF/CDF test) in consideration of actual environment. RILEM freeze-thaw tests are different from JIS A1148 freeze-thaw tests, which are widely adopted for evaluating the frost resistance of conventional concrete in Japan, in water absorption, cooling rate, length of freezing and thawing period, and number of freezing and thawing cycles. RILEM CIF test measures internal damage and is primarily applicable for pure frost attack. CDF test is appropriate for freeze-thaw and de-icing salt attack. JIS A1148 procedure A/B showed extremely low frost resistance of porous concrete if the large continuous voids were filled with water and the ice expansion in the large continuous voids set in during cooling. Frost resistance of porous concrete was improved by mixing coarse aggregate (G7) which particle size is smaller and fine aggregate in JIS freezing and thawing tests. RILEM CIF/CDF test showed that freeze-thaw and de-icing resistance of porous concrete was seems to be superior in that of conventional concrete.