• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.2
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• pp.112-119
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• 1991

Some experiments were carried out to investigate the effects of freezing and thawing on the strength and strain characteristics of alluvial silty clay under the different temperatures, loading and moisture conditions. The results were as follows; 1. The soil used was proved to be consisted of silty clay with honey-combed structure, and showed higher dilatancy, frost activity and lower stability in natural state. 2. Soil treated with freezing and thawing cycles showed lower compressive strength compared with the non treated, The strength decreased with incement of freezing and thawing cycles. It's shapes of stress-strain curves were flat and did not formulate a peak while the peak strength of higher moisture content soil decreased with the increment of moisture content. It's decrement ratio was most distinctly shown at the first one cycle of freezing and thawing. 3. The cohesion decreased due to freezing and thawing cycles but internal frcition angle was not changed. 4. The liquid limit decreased with increment of freezing and thawing cycles, and became almost constant after three cycles of freezing and thawing. 5. The strength under simple loading at failure mode was appeared to be higher compared with the cyclic loading after freezing and thawing but initial moisture content effect was not observed. 6. Ice lense was not observed within 50% of ice content ratio but observed over 100%. The higher the ice content ratio, the higher the peak strength. As a matter of fact, it seems that an optimum ice content ratio exists for plastic mode and the least compressive strength.

• Food Science of Animal Resources
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• v.18 no.2
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• pp.164-175
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• 1998

The objective of this study was to investigate the effects of freezing rate on ice crystal size and freeze-drying rate. Our experiments were carried out with self-manufactured freeze-dryer. Gelatin gels (2% w / w, 80$\times$20mm) were frozen unidirectionally (Neumann's model) from the bottom at -45, -30, -20, and -15$^{\circ}C$ and followed with freeze-drying. Under the upper conditions we measured freezing rate and the change of temperature and pressure during freeze drying. Freeze-dried gelatins were cut horizontally into 5 mm thickness from the bottom and measured their pore sizes. Also freeze-drying rate(primary drying) is estimated by measuring the temperature of sample and pressure of vacuum chamber. During freeze-drying, profiles of pressure and temperature were shown constant tendency regardless of freezing temperature and we could expect the end-point of freeze drying by considering pressure and temperature together. In temperature profiles, the point which temperature increased significantly was observed during freeze-drying. There is no relationship between freeze temperature and drying rate of primary drying in our model system. As freezing temperature increased, ice crystal size(X*) which correspond to 63.2% of cumulative frequency was increased and at the same freezing temperature ice crystal size(X*) was decreased with distance from the bottom of the sample. Freezing conditions have a strong influence on the quality of the final freeze-dried products in freeze-drying system.

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.71-77
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• 2010

Anti-freezing layer does not used in case of non frost heaving in subgrade soils. In this case, the modulus of subgrade soils were varied with freezing and thaw cycles under non frost heaving. That effect should be properly considered in pavement design. Impact resonance test that is nondestructive testing method was used for continuously determining the modulus of subgrade soils during freezing and thaw cycle. The modulus of subgrade soils was identical with freezing and thaw cycles under closed freezing and thaw system which is no water supplement into specimen during testing. There was also no difference in the modulus of subgrade soil between before and after freezing-thaw cycles for all specimens with different water content and density. That is thaw-weakening of subgrade soils do not occur under closed freezing and thaw system. The moduli at freezing conditions are varied with water content and density, but it can be ignored in practical design sense.

• Asian Journal of Turfgrass Science
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• v.4 no.1
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• pp.49-55
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• 1990

Experiments were conducted to investigate the relationships between the soil freezing depth and the accumulated degree-day of temperature below $0^{\circ}C$ at 17 locations during 1989-1990 winter season in kangwon province. The observed results are as follows : 1.When accumulated degree-day of temperature below at was 141t at late January soil freezing depth of sunny place was 46.5cm, that of shaded lot was 59 cm, and that of marginal place sunny or shaded area was 55cm, in Chun cheon. 2.Accumulated degree-day of temperature below at of Dae gwangryong area was more than that of Un-du, whereas soil freezing depth of Dae gwangryong was lower that of Un-du. It was considered that snow covering worked as heat insulator. 3.Soil freezing depth of vinyl mulching on Zoysia turf was less by around 2Ocm than that of non-vinyl mulching. Rice hulls covering of 4Ocm showed the great heat insulation effects with the soil freezing depth of 1.5cm at sunny place and 6.5cm at shaded lot compared to that of 47cm at sunny and 59.5 cm at shaded place bare ground. 4.Among investingated areas, Dunae, Honeg seong gun was the deepest soil freezing, 89cm with $569^{\circ}C$ of accumulated degree-day of temperature below $0^{\circ}C$ at late February. 5.dehydration of Juniperus C. var. Kaizuca, Euonymus japonica, and Chamaecyparis pisifira at winter season was around 5 %, however dehydration of Vinca minor was more than 10 %. A Studies on the Soil Freezing Depth and Change of Moisture contents in evergreen Plants upon subzero Temperature in Kangwon area.(2)

• International Journal of Industrial Entomology and Biomaterials
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• v.47 no.2
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• pp.126-133
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• 2023

Genetic resources of mulberry trees are commonly preserved as trophosomes, which are vulnerable to environmental factors, such as natural disasters, diseases, and pests. This study establishes a basic protocol for ultra-low temperature cryopreservation of mulberry trees using a two-step freezing process. The procedure was established using the "Daeshim" variety and then tested on genetic resources from 24 other mulberry varieties. Samples were first dried to a moisture content of 33-43% in a low-temperature forced-air chamber at -5 ℃, then slowly frozen from -5 ℃ to -20 ℃, and preserved in liquid nitrogen (-196 ℃). To determine the regeneration rate, isolated dormant buds were inoculated into MS basal medium, and grown shoots were grafted onto 1-year-old rootstock via chip budding and then cultured. After freezing in liquid nitrogen, the "Daeshim" variety exhibited a survival and regeneration rate of more than 70% and 50%, respectively. Applying the two-step freezing process to genetic resources from 24 mulberry species yielded average survival and regeneration rates of 85.3% and 75.5%, respectively. Morus alba showed survival and regeneration rates of 100%, confirming the efficacy of the two-step freezing method. These results indicate the high feasibility of ultra-low-temperature cryopreservation through two-step freezing of dormant buds from mulberry genetic resources. Additional research is required into the variations in regeneration rates with freezing period in liquid nitrogen.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.04a
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• pp.163-168
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• 1994

If the concrete is exposed below freezing point of the outer temperature before hardened, the quality of the concrete will be lowered after hardened. Anti-freezing agent which doesn't corrode the steel bar and doesn't generate the alkali-aggregate reaction by noncholride recently developed in Japan and Northern Europe. But the effects of these agents are rarely known. Therefore, this study is desigend for analyzing the freezing properties at the condition of solution of solution and cement paste. And this study aims to present the reference data for practical use of the concrete works using anti-freezing agent.

• Korean Journal of Animal Reproduction
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• v.12 no.2
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• pp.84-90
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• 1988

This study was done with mouse embryos to determine effects of the freezing media with or without 10% sucrose, and seeding methods (pincette, no seeding, liquid nitrogen gas phase and copper wire coiled straw) on embryo survival were determined using the FDA test. The summarized results are the following. 1. The FDA score found with copper wire coiled straw, no seeding, pincette and liquid nitrogen gas phase was 3.6, 3.6, 3.3 and 3.0, respectively. There were no significant differences. 2. The embryo score shows higher (P<0.05) survival rate using a freezing medium with sucrose than the one without it. Among the seeding procedure, better resutls are copper wire coiled straw and no seeded. 3. The results suggest that copper wire coiled seeding no seeding be as good as seeding when the mouse embryos were frozen in a liquid nitrogen container using both the freezing and dilution media containing 10% sucrose.

• Korean Journal of Animal Reproduction
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• v.11 no.2
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• pp.122-126
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• 1987

This study was carried out to investigate the effects of the glycerol equilibration methods and embryo grades before freezing on the survival rate after thawing in mouse embryos. The results obtained from this study were as follows: 1. The number of embryos of grade I(Excellent), II(Good) and III(Fair) before freezing in this study was 97(27.4%), 160(45.2%) and 97(27.4%), respectively. 2. The average survival rate of frozen-thawed embryos in 3 and 5 steps glycerol equilibration was 66.7% and 64.1%, and the rate of transfererable embryos after culture was 68.9% and 69.0%, respectively. 3. Out of embryo grade I and II before freezing, the transferable rate after thawing was 75.2% and 48.1%, respectively, and grade I embryos before freezing was higher transferable rate than that of grade II.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.345-348
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• 2006

FRP composites which are used in strengthening existing structure are usually adhered to the concrete surface, their performance are directly affected by environmental condition such as freezing-thawing and moisture. Accordingly, it is required to evaluate bond durability between FRP composite and concrete as well as FRP materials itself. The durability characteristics of FRP composite for freezing-thawing are evaluated in this study with the variables of concrete strength, type of FRP composite, freezing-thawing conditions and freezing-thawing cycle. In addition, material durability of GFRP sheet for high temperature/high humidity condition are examined in this experimental study.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.97-101
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• 2008

As the number of concrete building structures in marine environment increases, it is important to study and predict the durability and the compound deterioration of the concrete which is exposed in both chloride and freezing-thawing damage. The concrete's resistance against freezing and thawing is tested based on KS F 2456, while its chloride ion diffusion coefficient is evaluated based on NT BUILD 492. In result, the more exposure to freezing and thawing process, the shorter life it gets, due to the increased amount of chloride ion diffusion coefficient.