• Journal of the Korea Concrete Institute
• /
• v.13 no.4
• /
• pp.397-405
• /
• 2001

In clod weather regions, a strong seasonal wind brings sea salts to the land. In addition to it, recently, the spreading amount of deicing salts has increased numerously for purpose of removing snow and ice. Thus the salts environment around concrete structures becomes so severe that various damages of concrete due to applied salts will be brought up. Much of countries such as America, Europe etc. is carried out study for effects of deicing salts on concrete. However, there are not test methods for deterioration of concrete subjected to both freezing-thawing and chloride in Korea. In this study, we carried out test for the compound deterioration subjected to both freezing-thawing and chloride attack, to investigate the effects of sodium chloride on the deterioration of concrete. The test was performed to investigate the effects of cement type, strength and air content on the scaling deterioration of concrete. As a result, the scaling deterioration was accelerated in the presence of salts. And the resistance to scaling was strongly influenced by the type of cement, the strength and air content of concrete.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.14 no.2
• /
• pp.171-175
• /
• 2010

This paper presents the experimental results of frost durability characteristics including freezing-thawing and de-icing salt scaling of the concrete for gutter of the road and marine structure. Mixtures were proportioned with the three level of water-binder ratio(W/B) and three binder compositions corresponding to Type I cement with 0%, 30% and 50% GGBS(Ground granulated blast furnace slag) replacement. Also, two different solutions of calcium chloride were used to evaluate their effect on the frost durability resistance. Specially, in case of complex of freezing and thawing with salt and carbonation, the deterioration of concrete surface is evaluated. Test results showed that the BFS30 and BFS50 mixture exhibited higher durability and lower mass loss values than those made with OPC mix and the use of GGBS can be used effectively in terms of economy and frost durability of the concrete to be in complex deterioration. Therefore, the resistance to complex deterioration with freezing-thawing was strongly influenced by the strength and the type of cement.

• The Journal of the Korea Contents Association
• /
• v.18 no.11
• /
• pp.455-461
• /
• 2018

This paper presents experimental investigations about flexural strength and durability of reinforced concrete beams repaired using ductile fiber reinforced cementitious composite (DFRCC) and carbon fiber sheet through freezing and thawing test. Total 14 RC beams of $100{\times}100{\times}400mm$ size were tested by 3-point bending and freezing and thawing test by KS F 2456. The beams were reinforced using 3D10 steels on both the tensile and compressive sides, and repaired on 3 sides expect on top cycle. Test results showed that the beams repaired using fiber carbon sheet revealed about 15% higher values of flexural strength compared than the cases of DFRCC motar. On the other hand, the results did not showed meaningful differences in the aspect of durability. For further research, consideration of the steel interference effect and real old specimens such as taken from real deteriorated structures are needed to be tested after repairing with DFRCC and carbon fiber sheet.

• Geomechanics and Engineering
• /
• v.18 no.2
• /
• pp.189-203
• /
• 2019

Brine leakage is a common phenomenon during construction facilitated by artificial freezing technique, threatening the stability of frozen wall due to the continual thawing of already frozen domain. This paper takes the frequently encountered soft clay in Wujiang District as the study object, and remolded specimens were prepared by mixing calcium chloride solutions at five levels of concentration. Both the deformation and pore water pressure of frozen specimens during thawing were investigated by two-stage loading tests. Three sections were noted from the changes in the strain rate of specimens during thawing at the first-stage load, i.e., instantaneous, attenuated, and quasi-stable sections. During the second-stage loading, the deformation of post-thawed soils is closely correlated with the dissipation of pore water pressure. Two characteristic indexes were obtained including thaw-settlement coefficient and critical water content. The critical water content increases positively with salt content. The higher water content of soil leads to a larger thaw-settlement coefficient, especially at higher salt contents, based on which an empirical equation was proposed and verified. The normalized pore water pressure during thawing was found to dissipate slower at higher salt contents, with a longer duration to stabilize. Three physical indexes were experimentally determined such as freezing point, heat conductivity and water permeability. The freezing point decreases at higher salt contents, especially as more water is involved, like the changes in heat conductivity. The water permeability maintains within the same order at the considered range of salt contents, like the development of the coefficient of consolidation. The variation of the pore volume distribution also accounts for this.

• The Journal of the Korea Contents Association
• /
• v.20 no.12
• /
• pp.529-536
• /
• 2020

This paper presents experimental investigations about compressive strength and durability of reinforced concrete compressive members repaired using ductile fiber reinforced cementitious composite (DFRCC) and carbon fiber sheet through freezing and thawing test. Total 24 RC specimens of 100x100x400mm size were tested by compressive strength test and freezing and thawing test by KS F 2456. The specimens were reinforced using 4D10 steels and repaired on 4 sides expect on top cycle. Test results showed that the specimens repaired using fiber carbon sheet revealed about 5% higher values of the compressive strength compared than the cases of DFRCC motar. On the other hand, the resurts did not showed meaningful differences in the aspect of durability. For further research, considerations of the steel interference effect and real old specimens such as taken from real deteriorated structures are needed to be tested after repairing with DFRCC and carbon fiber sheet.

• Food Science of Animal Resources
• /
• v.42 no.2
• /
• pp.341-349
• /
• 2022

The objective of this study was to examine the effect of temperature abuse prior to cold storage on changes in quality and metabolites of frozen/thawed beef loin. The aerobic packaged samples were assigned to three groups: refrigeration (4℃) (CR); freezing (-18℃ for 6 d) and thawing (20±1℃ for 1 d), followed by refrigeration (4℃) (FT); temperature abuse (20℃ for 6 h) prior to freezing (-18℃ for 6 d) and thawing (20±1℃ for 1 d), followed by refrigeration (4℃) (AFT). FT and AFT resulted in higher volatile basic nitrogen (VBN) values than CR (p<0.05), and these values rapidly increased in the final 15 d. Cooking loss decreased significantly with an increase in the storage period (p<0.05). In addition, cooking loss was lower in the FT and AFT groups than in the CR owing to water loss after storage (p<0.05). A scanning electron microscope (SEM) revealed that frozen/thawed beef samples were influenced by temperature abuse in the structure of the fiber at 15 d. Metabolomic analysis showed differences among CR, FT, and AFT from partial least square discriminant analysis (PLS-DA) based on proton nuclear magnetic resonance (¹H NMR) profiling. The treatments differed slightly, with higher FT than AFT values in several metabolites (phenylalanine, isoleucine, valine, betaine, and tyrosine). Overall, temperature abuse prior to freezing and during thawing of beef loin resulted in accelerated quality changes.

• Korean Journal of Animal Reproduction
• /
• v.15 no.2
• /
• pp.133-139
• /
• 1991

This stduy was carried out in order to investigate the effects of concentration and equilibration time of cryoprotective agents on survival rate of slow and ultrarapidly frozen in vitro fertilized bovine embryos. In vitro fertilized bovine embryos, following dehydration by cryoprotective agents and sucrose, were slowly freezed(from 2$0^{\circ}C$ to -7$^{\circ}C$/-1$^{\circ}C$/min., from -7$^{\circ}C$ -35$^{\circ}C$/-0.2$^{\circ}C$/min. from -35$^{\circ}C$ to -38$^{\circ}C$/-0.3$^{\circ}C$/min.) by cell freezer and directly plunged into liquid nitrogen and thawed in 38$^{\circ}C$ water. Survival rate was defined by development rate to the morula and blastocyst stage after in vitro cultured and FDA test. The results are summarized as follows : 1. The survival rates of in vitro fertilized bovine embryos after slow frozen-thawing in the freezing medium of 0.25M sucrose added 2.5M glycerol, 3.0M DMSO, 2.0M propanediol and 2.5M glycerol＋2.0M propanediol were 84.3%, 85.9%, 77.8%, 74.3%, respectively. 2. The survival rates of in vitro fertilized bovine embryos after slow frozen-thawing in the freezing of 0.50M sucrose added 2.5M glycerol, 3.0M DMSO, 2.0M propanediol and 2.5M glycerol＋2.0M propanediol were 83.8%, 85.1%, 71.4%, 74.6%, respectively. 3. The survival rates of in vitro fertilized bovine embryos after ultrarapid frozen-thawing in the freezing of 0.25M sucrose added 2.5M glycerol, 3.0M DMSO, 2.0M propanediol and 2.5M glycerol＋3.0M propanediol were 69.3%, 70.8%, 63.2%, 67.1%, respectively. 4. The survival rates of in vitro fertilized bovine embryos after ultrarapid frozen-thawing in the freezing of 0.25M sucrose added 2.5M glycerol, 3.0M DMSO, 2.0M propanediol and 2.5M glycerol＋2.0M propanediol were 69.4%, 70.1%, 62.3%, 63.5%, respectively. 5. The survival rates of in vitro fertilized bovine embryos after slow and ultrarapid fromthawing in the freezing medium of sucrose added cryoprotective agents were not significant difference between 5min. and 10min. of equilibration time.

• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.11
• /
• pp.1553-1558
• /
• 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.

• Journal of Animal Reproduction and Biotechnology
• /
• v.39 no.2
• /
• pp.88-94
• /
• 2024

Background: Using cryovial for freezing dog spermatozoa provides a practical method to increase extended sperm volume and shorten the time required for equilibration by using a simple freezing techniques. The purpose of this study was to determine the optimal thawing condition for dog sperm cryopreservation using cryovials. Methods: For sperm freezing, cryovials with 200 × 10⁶ sperm/mL were cooled after the addition of tris egg yolk extender (TEY) at 4℃ for 20 min, then TEY with 4% glycerol was added and equilibrated for another 20 min before being aligned over LN₂ vapor for another 20 min and plunged directly into LN₂. Spermatozoa were thawed in a water bath at 37℃ for varying times (25 sec, 60 sec, 90 sec, and 120 sec) in the first experiment. In the second experiment, spermatozoa were thawed in a water bath at various temperatures and times (37℃ for 1 min, 37℃ for 1 min with gentle stirring, 24℃ for 24 min, and 75℃ for 20 sec). In these experiments, the effect of thawing conditions on motility parameters, viability (SYBR-14/PI), and acrosome integrity (PSA/FITC) of spermatozoa were investigated. Results: The post-thaw sperm motility parameters, viability, and acrosome integrity were not significantly different across the experimental groups. Conclusions: In this study, the characteristics of spermatozoa frozen using cryovials were not significantly affected by various thawing conditions.

• Journal of the Korean Geosynthetics Society
• /
• v.6 no.3
• /
• pp.1-7
• /
• 2007

The property of weathered soil cannot but have a possibility of having a limit when its precise approaching due to the various weathering environment, and the peculiarity of its conduct affected by the weathering degree and effect factors. Especially most domestic or international researches are concentrated on the sedimentary soil, trying to analyze the mechanical behavior of weathered soil from the viewpoint of sedimentary soil. Therefore, it's difficult to judge if those results meet the actual conduct of weathered soil. This study suggested a way of weathering degree changing experiment as an early stage in an experiment of artificially changing weathering degree. In order to find out the property of strength change by the change of weathering degree, indoor mechanical experiment was made using soil sample after freezing and thawing. Under the weathering degree, characteristic change is watched by country rock and region of weathered granite soil.