• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.321-324
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• 2000

Cell culture of Angelica gigas Nakai producing decursin and decursinol angelate as secondary metabolites were preserved in liquid nitrogen after pre-freezing in deep $freezer(-70^{\circ}C)$. The development of optimal procedure for cryopreservation was investigated by using cryoprotectant and pre-treatment before cooling. 0.7 M sucrose was found be the optimum osmotic pre-conditioning culture medium compared to mannitol, sorbitol and NaCl with the same osmotic pressure. In pre-culture medium, cells in exponential phase, supported the best growth after cryopreservation. Effective cryoprotectant was proved to be a mixture of sucrose, glycerol, DMSO. Higher concentration of cryoprotectant was better for cell viability. The highest relative cell viability established after the development of optimal procedure was 65%.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.139-139
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• 2003

최근, 한우의 수정란 체외이식두수가 급격히 늘어나고 있으나, 모축의 등록번호를 대부분 확인 할 수 없으며, 확인이 가능할지라도 개체별 수정란의 생산이 거의 이루어지지 않고 있다. 본 실험에서는 모축의 등록번호가 확인된 개체의 난소로부터 채취한 난포란만을 체외성숙, 수정, 배양하여 배 발생율을 조사하고, 동결성적을 조사하였다. 도축된 한우의 난소를 개체별로 채취하여 2$0^{\circ}C$생리식염수에 넣어 3시간 이내에 실험실로 운반하고, 난포란을 채취하였다 개체별로 채취한 난포란은 9~47개/난소였고, 평균 14.3개/난소였다. 개체별 난포란은 IVMD 101 (일본, 펩티트연구소)에서 22물24시간 동안 체외 성숙시킨 후, IVF 100(일본, 펩티트연구소)으로 2회 세정한 후, 각각의 배양액 50${\mu}\ell$ 소적에 5개씩 5~6시간 수정시켰다. 수정란을 저 산소 배지 IVD 101 (일본, 펩티트연구소)로 7~9일간 배양하여 배 발생율을 조사하고 동결하였다. 평균 수정율은 81%, 배반포의 발생율은 35% 였으며, 동결 가능한 수정란은 평균 4개/두 정도 얻을 수 있었다. 이상의 결과로 한우의 개체가 확인된 난소로부터 수정란생산이 가능하고, 육질등급이 우수한 한우의 수정란생산이 가능해졌으며, 앞으로 고 능력 젖소의 난소에서도 고능력 수정란의 생산이 가능할 것으로 사료된다.

• 보존과학연구
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• s.35
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• pp.45-55
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• 2014

The small dining tables which are made of bamboo were deteriorated condition when those were excavated from Mado shipwreck No.1. Therefore, preliminary test was conducted for consolidation (Sucrose, Dammar gum, Cetyl alcohol and Polyethylene glycol 4000) then impregnated and vacuum freeze dried. After the test, since the treatment with vacuum freeze drying using an aqueous solution of PEG 4000 keep the shape well the most and present bright colour, waterlogged archaeological bamboo conserved with vacuum freeze drying using an aqueous solution of PEG 4000. One bamboo table consolidated with soluble PEG 4000 from 10% to 40%, then vacuum freeze dried. Another impregnated with soluble PEG 4000 from 10% to 70%. After that, it was separated and held in polycarbonate sheet for preventing bending during dry. The small dining tables are the three dimensional shapes and have some loss. Therefore the mounting for support tables were necessary which are made of acrylic sheet. It keep the table shape and make it convenient for storage and handling.

• Polymer(Korea)
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• v.27 no.4
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• pp.349-357
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• 2003

Hydrogels for wound dressing from a mixture of poly(vinyl alcohol) (PVAL), poly(N-vinyl pyrrolidone) (PVP), hexylene glycol (HG) and chitosan were made. The hydrogels were obtained by physical crosslinking of freezing and thawing, chemical crosslinking of irradiation, and irradiation after freezing and thawing of mixture solutions. The solid concentration of PVAL/PVP/HG/chitosan was 15 wt%. The concentration of chitosan was 0.3 wt%, and the ratio of PVAL/PVP was 6:4. The concentration of HG was in the range of 1∼5 wt%. The number of repeated freezing and thawing was in the range of 1∼3 times, and gamma irradiation doses were 25, 35 and 50 kGy. The physical properties such as gelation, water absorption and gel strength of hydrogels were examined. Gel content and gel strength decreased as HG concentration increased, whereas degree of swelling increased. Gel content and gel strength increased as irradiation dose and the number of freezing and thawing increased, whereas degree of swelling decreased. The hydrogels were evaluated for the healing effect for animals and for the antibacterial effect.

• Magazine of the Korea Concrete Institute
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• v.4 no.1
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• pp.89-96
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• 1992

It is generally known that the frost-resistance of concrete is much affected by the air content in concrete and by the air void system or air distribution. And also the frost-resistance is believed to vary with the stre¬ngth of concrete. This article is prepared to describe, based on experiment, the effect of the air content and the air void system, particularly the effect of the spacing factor, on the freeze-thaw resistance of the high strength conc¬rete. For this purpose, I first worked on Non-AE concrete to make its compressive strength set about 400 to 500 kg/em'. However, the freeze-thaw test on the Non-AE concrete resulted in low durability factor, I.e., 10-2~0%. Thus to enhance the durability, another supplementary step was needed. I used AE admixture. which enhanced durability by changing the air content from 2% to 12%. The frost-thaw test was then performed 500 cycles on the 20 kind of concrete mixtures which differ in unit cement content and in water-cement ratio. Keywords : frost -resistance, air content, air void system, air distribution, spacing factor, freeze-thaw test, dur ability factor. capillary cavity, Linear Traverse Method.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.45-56
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• 2014

Frozen ground in cold region consists of an upper active layer and lower permafrost which is permanently frozen land. During the summer season, the air temperature is high enough to make the frozen ground melt, which causes the reduction of soil strength and thaw settlement. These phenomena result in structural instability, so it is necessary to apply frozen ground stability techniques. Thermosyphon is a closed natural two-phase convection device to maintain the ground temperature below $0^{\circ}C$ by extracting heat from the ground and discharges it into the atmosphere. Experimental and numerical investigation has been performed to estimate the effect of the refrigerant filling ratio in thermosyphon using R-134a refrigerant and the thermal conductance of the thermosyphon.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.2
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• pp.143-151
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• 2022

In this study the relative dynamic modulus and surface rebound hardness measurement methods were used for comparison to predict the occurrence of frost dam age on the concrete. From the test results, it was observed that the initiation of concrete dam age predicted by surface rebound hardness values was 200 cycles quicker than that of the relative dynamic modulus method in the W/C 70 specimens. In addition, it continuously provided data that showed the frost damage development of concrete surfaces according to increasing freeze-thaw cycles. This indicated that the frost dam age of the concrete could be found from the initial point of its occurrence by the surface rebound hardness measurement method. Similar results were also observed in W/C 60 and 50 specimens. Therefore, it is considered that surface rebound hardness method predicted the freeze-thaw damage well, regardless of water-cement ratio.

• Journal of the Korean Geotechnical Society
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• v.25 no.9
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• pp.19-27
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• 2009

In order to investigate anti-freeze process of precast concrete L-type retaining walls in cold regions, test walls were installed in the campus of Kitami Institute of Technology (KIT, Hokkaido, Japan). The wall consists of following three sections, i) back filled with frost susceptible clay soil, ii) using thermal insulation material, and back filled with frost susceptible soil, iii) back filled with frost-unsusceptible soil. The freezing front distribution and ground temperature within the backfill were observed and deflections of the walls were measured over three freeze-thaw seasons. Some understanding of the mechanisms of the build-up of frost heave pressure was gained, and the effectiveness of replacement method was observed. A simulation was performed to predict the shape of the freezing front in the backfill behind L-type walls with various cross sections. These findings were employed to propose a method for determining the appropriate zone to be replaced with frost unsusceptible backfill material in cold regions.

• Proceedings of the KSEEG Conference
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• 2007.04a
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• pp.612-614
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• 2007

• Korean Journal of Food Science and Technology
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• v.38 no.2
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• pp.249-255
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• 2006

The optimum culture conditions for the ice nucleating activity and the cell growth of Xanthomonas translucens KCTC 2751 were investigated. The optimum initial pH and temperature for the cell growth and the ice nucleating activity were 6.5 and $25^{\circ}C$, respectively. The optimum culture medium for the ice nucleating activity was composed of 1.0% maltose, 1.4% yeast extract, 0.8% digested of gelatin, and 0.03% KCI in distilled water. Freezing operations carried out on distilled water showed that the degrees of supercooling were $-7.90^{\circ}C$ without ice nucleators, $-1.56^{\circ}C$ with silver iodide as a commercial ice nucleator, and $-1.36^{\circ}C$ when Xanthomonas translucens KCTC 2751 were added. During progressive freeze-concentration assays, the addition of Xanthomonas translucens KCTC 2751 led to lower saccharose concentrations in the crystals, while the cells led to higher saccharose concetrations in the concentrated phase.