• Geomechanics and Engineering
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• v.29 no.3
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• pp.349-357
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• 2022

Abnormal climate events are occurring frequently around the world. In particular, cold waves and heavy snow lead to damage and deterioration of facilities, which can cause loss of life or property damage, such as shortening the lifespan of facilities. Therefore, it is very important to prepare an appropriate maintenance system and to establish a strategy to cope with abnormal weather conditions. In this study, laboratory freezing experiments were performed to analyze the freeze-thaw characteristics affecting the tunnel concrete lining, and heat flow analysis was carried out based on the test results. Based on these experimental and theoretical analysis results, quantitative freeze-thaw evaluation criteria for tunnel concrete linings were proposed.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.6
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• pp.55-61
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• 2018

This study aims to analyze the performance of Heated-nonslip using renewable energy to prevent nonslip freezing during winter. For this purpose, power generation system and congratulatory devices using solar energy are designed, and it is designed to provide regular electricity to heat up nonslip through Electrical storage system(ESS). In this study, It is intended to analyze the level of electrical energy suitable for nonslip using 24V or 48V, and to measure the temperature changes and temperature distribution according to the location of the test object. As a result of the experiment, nonslip's frame temperature was measured at $-7.5{\sim}-5^{\circ}C$ on average, and $-1{\sim}-2^{\circ}C$ on the heating cable during the supply of 24V and this could not be the solution for defrosting freezing nonslip in the winter. As a result of heating nonslip by supplying 48V with an electrical power of 8W, the temperature of the nonslip was shown to be between $5^{\circ}C$ and $11^{\circ}C$ to $13^{\circ}C$. Even if the power supply was switched on and off every minute, the temperature did not drop below $4^{\circ}C$ and the frozen ice melted on the nonslip without freezing.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.6-6
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• 2000

On-orbit thermal behavior of KOMPSAT (Korea Multi-purpose Satellite) propulsion system employing hydrazine (N$_2$H$_4$) liquid monopropellant is addressed. Thermal control performance to prevent propellant freezing in spacecraft-operational orbit was verified by flight telemetry data obtained during LEOP (Launch and Early Operation Phase). Results are depicted in terms of temperature history during several orbits selected and are compared with acceptable temperature ranges of system components. Cyclic behavior of temperature is reduced into duty cycles of the avionics heaters and subsequently converted into the electrical power required to keep away from propellant freezing. Temperature of each component which was achieved under on-ground thermal-balanced condition of spacecraft, is presented for comparison with the flight data, additionally.

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.1
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• pp.18-23
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• 2017

In 2015, 100-car pileup was happened because the safe distance from the car in front did not be kept due to much fog at YoungJong Bridge in South Korea. This is why the road would be benumbed with cold weather in winter. For this weather condition, if the driver of the car in front changed the lane suddenly or suddenly slammed on the brake in fog or freezing area, the braking distance of the real car has to be 2 or 3 times longer than usual. In this paper, we have simulated the function that warns and notice about the fog area or the freezing one in the road using Arduino sensors and Beacon. Also we propose the intelligent traffic system to protect the accidents in winter.

• Clinical and Experimental Reproductive Medicine
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• v.45 no.3
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• pp.110-115
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• 2018

Objective: To compare our in-house method of embryo freezing with Cryotop vitrification in terms of immediate survival, subsequent cleavage and blastocyst formation, and cell numbers in blastocysts. Methods: Two-cell mouse embryos were randomly allocated into three groups: a non-frozen control group (group 1, n = 300), a group that underwent Cryotop vitrification (group 2, n = 300), and a group that underwent our in-house freezing method (group 3, n = 300). Results: There were no significant differences between groups 2 and 3 in the immediate survival rate (96.3% vs. 98.6%, respectively; p= 0.085), the further cleavage rate (91.7% vs. 95.0%, respectively; p= 0.099), or the blastocyst formation rate (80.7% vs. 78.6%, respectively; p= 0.437). The cell numbers in the blastocysts from groups 1, 2, and 3 were comparable ($88.99{\pm}10.44$, $88.29{\pm}14.79$, and $86.42{\pm}15.23$, respectively; p= 0.228). However, the percentage of good-quality blastocysts in the Cryotop vitrification group was significantly higher than in the group in which our in-house method was performed, but was lower than in the control group (58.0%, 37.0%, and 82.7%, respectively; p< 0.001). Conclusion: At present, our method is inferior to the commercial Cryotop vitrification system. However, with further improvements, it has the potential to be useful in routine practice, as it is easier to perform than the current vitrification system.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.21-32
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• 2011

The frost penetration depth of pavement is usually estimated from the freezing index that made temperature data analysis of 30 years and decided the thickness of anti-frost layer. The field monitoring region in study was divided into five regions by freezing index 550~650$^{\circ}C{\cdot}$day, 450~550$^{\circ}C{\cdot}$day and 350~450$^{\circ}C{\cdot}$day. Each region has three-section of road pavement such as cutting area, boundary area of cutting and banking, and lower area of banking. The field monitoring system was established both in the section of anti-frost layer and in the section without anti-frost layer. The data analysis was conducted for determination of frost penetration depth within the paved road by the field monitoring system. The result showed that The temperature of subgrade without anti-frost layer shows below zero in centigrade for the region of freezing index 550~650$^{\circ}C{\cdot}$day, up and down around zero degree in subgrade for the region of freezing index 450~550$^{\circ}C{\cdot}$day, and there is no place existed below zero degree in subgrade for the region of freezing index below 450$^{\circ}C{\cdot}$day. With comparison of field frost penetration depth for the cross-sections of pavement, the cutting area shows the greatest frost penetration depth, and less influence of frost penetration depth for the boundary area of cutting and banking, and the least influenced for the lower area of banking.

• Journal of Embryo Transfer
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• v.23 no.3
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• pp.217-222
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• 2008

In previous studies, we reported that sow which was transferred OPS-freezing embryos not able to deliver a piglet (Kim et al, 2004). This study was conducted to investigate a possibility of gilt as recipients which produce piglets after transfer of OPS-freezing embryos. All transferred embryos were prepared by in vitro production (IVP) system. In vitro culture (IVC) medium used glucose-free NCSU23 supplemented with 5mM sodium pyruvate, 0.5 mM sodium lactate and 4 mg/ml bovine serum albumin for 2 days at $39^{\circ}C$. From day 3 of IVC, 10% fetal bovine serum albumin was added to the culture medium. In preparing of freezing embryos, embryos were treated with 7.5 $\mu g/ml$ cytochalasin-B for 30 min and centrifuged at $13,000{\times}g$ for 13 min. And then, embryos were exposed sequentially to an ethylene glycol (EG) solution, aspirated into open pulled straw (OPS), and plunged or thawed into the liquid nitrogen. In embryo transfer (ET), we used two kinds of type (surgical method vs. non-surgical method). In surgical method of embryo transfer, $55\sim65$ embryo were transferred in both uterine horn of two recipient gilts by plastic straw. Non-surgical method which is like artificial insemination was performed on three gilts. Each 140 frozen embryos were transferred to two gilts and 40 fresh embryos to one gilt. Pregnancy establishment was shown one recipient at 45 days after ET. However, the one recipient was also aborted at 58 days after ET. These results suggest that gilts can be considered as a candidate of recipients for OPS-freezing embryo transfer.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.1
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• pp.69-76
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• 1995

Cold acclimation involves changes in gene expression. BN28 and BN115 are two genes which are regulated by cold temperature and assumed having roles in cold acclimation. The objectives of this experiment was to explore the expression of BN28 and BN115 under field conditions. Six winter cultivars were planted at three different dates during the fall. The expression of the genes was determined by northern blot analysis of total RNA taken from leaves 15 to 30 day-intervals after planting. The expression of the two genes was detected within 15 days after planting well before onset of freezing tolerance in plants. This suggestes either their expression was a prerequisite of the freezing tolerance or their expression was regulated by other environmental factors as well as temperature. Two genes showed a different expression pattern suggesting they had a different regulatory system. Although timecourse increase in expression of the cold-regulated genes was matched with increase in freezing tolerance, the difference of expression in cultivar level at specific times of measurement was not correlated with freezing tolerance at the moment.

• Journal of Veterinary Clinics
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• v.21 no.4
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• pp.363-368
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• 2004

To investigate the effects of seeding during freezing procedure on post-thaw viability, motility, and acrosome integrity of boar spermatozoa, semen from 5 Yorkshire boars were collected for this experiment. Raw semen were diluted with Merck I, subsequently added with cooling diluent containing lactose and egg yolk and with freezing diluent containing glycerol. The diluted semen were frozen on the rack in the styrofoam box filled with liquid nitrogen at the distance of 5 cm or I cm above LN2 level. Seeding was performed to only a group of straws frozen at 5 cm away on the surface of LN2. The frozen semen were thawed in $50^{\circ}C$C water and the viability and local motility were analyzed by sperm analysis imaging system. A part of thawed semen was taken for the examination of morphology of apical ridge of the acrosome to compare with the effect of seeding between the seeding-treated and non treated groups. I. Post-thaw viability was considerably higher in seeding-treated sperm than non-seeding group (p<0.01), however, no difference of local motility was obtained among the groups. 2. At three hours after thawing, viability was also higher in seeding-treated group than non-treated group (p<0.05), along with no difference of motility among the groups. 3. Higher normal acrosome integrity was obtained in the seeding-treated sperm than non-treated groups (p<0.01). 4. Between non-seeded groups, higher normal acrosome integrity was obtained in the sperm group frozen at 5cm upper on the surface of LN2 than that frozen at 1cm away (p<0.01). These results indicated that seeding treatment during freezing boar spermatozoa was beneficial to post-thaw viability and normal acrosome integrity.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.319-323
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• 2018

Ferronickel slag is a by-product from the ferronickel smelting process and it is divided into air-cooled ferronickel slag and water granulated ferronickel slag according to cooling system. The purpose of this experimental resesrch is to investigate the mechanical properties and resistance to freezing and thawing of concrete using air-cooled ferronickel slag(ACFNS) fine aggregate. For this purpose, the concrete specimens with water-cement ratio of 50% were made with ACFNS's replacement ratios of 0%, 20%, 30%, 40%, 50%, 70%, and 100% by volume of fine aggregate. It was observed from the test results that the compressive strength and static modulus of elasticity of ACFNS fine aggregate concrete were increased with increasing replacement ratio of ACFNS and the resistance to freezing and thawing of this was similar to reference concrete which had the relative dynamic modulus of elasticity of more than 90% during the freezing and thawing of 300 cycles.