• 한국산림과학회지
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• 제28권1호
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• pp.31-35
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• 1975

본 실험(實驗)은 단기(短期) 저온처리(低溫處理)가 3개의 사과 품종(品種)과 양앵두의 휴면타파중(休眠打破中)인 가지(枝)의 내한성도(耐寒性度)에 미치는 효과(効果)를 연구하였다. 단기(短期) 저온(低溫)처리 효과는 저온(低溫)처리 후의 해빙(解氷)처리에 따라 다르게 나타났다. 해빙(解氷)처리와 함께 $-9^{\circ}C$까지의 결빙온도(結氷溫度)가 3시간(時問) 및복되어 처리되었을 때 사과 및 양앵도의 내한성도(耐寒性度)는 저온(低溫)처리에 의하여 $3{\sim}9^{\circ}C$ 만큼 뚜렷하게 높아졌다. 이와 반대로 해빙(解氷)처리가 없이 결빙온도(結氷溫度)($-9^{\circ}C$)가 10시간 전처리(前處理)되었을 때 내한성도(耐寒性度)는 저온(低溫)처리에 의하여 아무런 영향을 받지 않았다. 자연(自然)에서 일어나는 온도(溫度)의 결빙(結氷)-해빙(解氷) 반복의 역할은 위와 같은 자연적(自然的)인 온도(溫度) 자극이 휴면(休眠)이 깨어나고 있는 나무의 내한성(耐寒性)을 증진(增進)하여 초봄에 일어나는 만상(晩霜)의 피해(被害)에 적응(適應)할 수 있도록 하는데 있다고 고찰(考察)되었다.

• Journal of Ginseng Research
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• 제20권2호
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• pp.179-183
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• 1996

One exotherm was detected in the intact ginseng seeds containing more than 35% water, but in seeds with 20% there was no exotherm. The shapes of exotherm were remarkably uniform without relation to water content above 35%. The temperature at the initiation of freezing varied from -3.5$^{\circ}C$ to -9.6$^{\circ}C$ with the different water content in the seeds, and the Initial temperature of freezing delayed with the decrease of water content. The resistance damage at low temperature appeared in order of maln body, rhizome, lateral root of 3-year-old yearling rhizome, and fine root of 3-year-old. Ginseng roots didn't receive any damage at -5$^{\circ}C$ for 24 hours. Otherwise they received serious damage below -1$0^{\circ}C$ even for 5 hours'exposure. Hence, alternative low temperature gave more severe damage compared to constant low temperature. This result suggests that the Possibility of receiving injury at low temperature was higher during the thawing season of the early spring than in the winter.

• Journal of Biosystems Engineering
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• 제40권3호
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• pp.271-276
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• 2015

Purpose: Quick freezing is widely used in commercial food storage. Well-known freezing techniques such as individual quick freezing require a low-temperature coolant and small cuts for the heat-transfer efficiency. However, the freezing method for bulk food resembles techniques used in the 1970s. In this study, electromagnetic (EM) heating was applied to improve the quick freezing of bulk food. Methods: During freezing, the surface of food can be rapidly cooled by an outside coolant, but the inner parts of the food cool slowly owing to the latent heat from the phase change. EM waves can directly heat the inner parts of food to prevent it from freezing until the outer parts finish their phase change and are cooled rapidly. The center temperature of garlic cloves was probed with optical thermo sensors while liquid nitrogen (LN) was sprayed. Results: When EM heating was applied, the center cooling time of the garlic cloves from freezing until $-10^{\circ}C$ was 48 s, which was approximately half the value of 85 s obtained without EM heating. For the white radish cubes, the center cooling time was also improved, from 288 to 132 s. The samples frozen by LN spray with EM heating had a closer hardness to the unfrozen samples than the samples frozen by LN only. Conclusions: The EM heating during quick freezing functions to maintain the hardness of fresh food by reducing the freezing time from 0 to $-10^{\circ}C$.

• 설비공학논문집
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• 제4권3호
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• pp.175-182
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• 1992

Freezing of the binary solution ($H_2O-NaCl$) saturating a packed bed of spheres is investigated experimentally. The system is cooled through its top surface, and the bottom is maintained at a temperature above the liquidus. Experiments are performed on the hypolutectic side, and the cold wall temperature is lower than the eutectic point. The effects of initial mixture concentration, superheat and glass bead diameter on temperature and concentration distributions are investigated. Supercooling was observed only at early times of the freezing process for experiments with 5% initial salt concentration. Flow visualization experiments and mushy-liquid interface position observations revealed natural convection in the liquid region. Remelting phenomena was not observed at both the solid-mushy and mushy-liquid interfaces.

• 한국가축번식학회지
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• 제21권3호
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• pp.287-292
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• 1997

This study was carried out to investigate the effects of concentration and kinds of cryoprotectants, equilibraction time, thawing temperature and time, sucrose concentration on the survival rates of frozen bovine demi-embryos. The bovine demi-embryos following dehydration by cryoprotectants a various concentration of sucrose were freezed by cell freezer and thawed in 3$0^{\circ}C$ water bath. Survival and in vitro developmental rates was defined as development rates on in vitro culture or FDA-test. The results are summarized as follows : 1. The high survival rates of demi-embryos after frozen-thawing in freezing medium was attained 2.0M glycerol. The high survival rates of demi-embryos after frozen-thawing in freezing medium was obtained using single cryoprotectant(25.0~30.0%) than mixed cryoprotectants(16.7~19.0%). 2. The survival rates of demi-embryos after frozen-thawing in freezing medium added 1.5M, 2.0M glycerol＋0.25M sucrose(37.5~33.3%) were higher survival rates than those of sucrose concentration of 0.50, 0.75M(12.5~26.7%). 3. The equilibration time on the survival rates of demi-embryos was attained after short period of time(30.0~35.0%) in the freezing medium higher than long period of time(21.1%). 4. The thawing temperature on the survival rates of demi-embryos was attained at 3$0^{\circ}C$ of thawing temperature(26.7~40.0%) higher than $25^{\circ}C$ or 37$^{\circ}C$ of thawing temperature(13.3~20.0%). 5. The thawing time on the survival rates of demi-embryos was attained at 1~5 minutes of thawing time(26.7~33.3%) in the freezing medium higher than 10 minutes of thawing time(13.3~18.8%).

• Journal of Advanced Marine Engineering and Technology
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• 제41권3호
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• pp.176-181
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• 2017

본 연구는 저온환경에서의 평판형 열교환기에 대해 제빙을 억제할 수 있는 방법을 살펴보았으며, 그 방법으로 초음파의 발생에 따른 제빙특성을 관찰하였다. 본 실험에서 최적의 조건을 찾아내기 위해 에틸렌글리콜을 브라인으로 사용하고, 온도는 $-8{\sim}-16^{\circ}C$로 순환시켰으며, 제빙에 사용된 물은 1~3mm 두께로 공급하여 데이터를 기록하였다. 또한 초음파의 발생정도에 따른 변화를 확인하기 위해 출력을 조절하여 실험을 진행하였다. 그 결과 제빙억제 효과는 브라인 온도, 제빙두께, 초음파 주파수의 영향을 받는 것을 알 수 있었다.

• 한국수산과학회지
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• 제24권5호
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• pp.340-344
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• 1991

각종 어육의 동결 및 가열과정 중의 이화학적 품질변화의 규명하고 저온저장 및 가열조건의 확립과 장치의 설계를 위하여 필요로하는 열물성과 변성온도를 DSC를 이용 측정함으로서 다음의 결과를 얻었다. 1. 어육의 발열반응개시온도는 냉각속도가 증가할수록 강하하였으며, 활성화에너지, 엔탈피 및 엔트로피는 냉각속도의 증가와는 상반되는 경향을 보였다. 동결잠열은 냉각속도에 관계없이 거의 -정한 값을 나타내었다. 2. 어육의 동결과정 중의 자유에너지의 변화는 냉각속도와 조성성분의 영향보다는 온도에 의한 영향이 큰 것으로 나타났다. 3. 어육속의 지질 및 단백질의 변성온도는 가열속도와 상관관계를 나타내었으며, 지질의 함양이 많을수록 변성온도가 낮게 나타났다. 변성엔탈피는 각각 0.04-0.13, 0.07-0.17cal/g 값을 얻었다.

• International Journal of Industrial Entomology and Biomaterials
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• 제47권2호
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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.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1164-1171
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• 2010

Korea is considered to be a seasonal frozen soil area that is thawed in the spring, and most of the area is frozen in winter as to the characteristic of geography. In the current design codes for anti-freezing layer, the thickness of anti freezing layer is calculated by freezing depth against the temperature condition. Therefore, they have a tendency of over-design and uniform thickness without the considerations of thermal stability, bearing capacity and frost susceptibility of materials. So, it is essential for studying the appropriateness and bearing capacity besides the seasonal and mechanical properties of pavement materials to take a appropriate and reasonable design of the road structure. In this research, the evaluation of frost susceptibility on subgrade, ant-freezing layer, sub base was conducted by means of the mechanical property test and laboratory field road model downed scale experiment. The temperature, heaving amount, heaving pressure and unfrozen water contents of soil samples, the subgrade, anti-freezing layer, sub base soils of highway construction site, were measured to determine the frost susceptibility.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.543-550
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• 2000

Rock slopes along the road or railroad are affected by temperature and therefore experienced iterative freezing-thawing process between winter and early spring. The purpose of this study is to analyze the stability of rock slopes which are influenced by the deterioration due to the freezing-thawing. The analysis is the homogenization method which evaluates the strength property of discontinuous rock mass, and as a strength failure criterion, Drucker-Prager failure criterion is used. The deterioration property of real rock is obtained by a freezing-thawing laboratory test of tuff and this property of deterioration is quantitated and used as a basic data of stability analysis for rock mass. To evaluate the deterioration depth due to the freezing-thawing in situ rock slope, one dimensional heat conductivity equation is used and as the result I can find that the depth of which is affected by a temperature. After the freezing-thawing depth of model slope is determined, we analyze the pattern of rock mass stength value of rock slope model which excesses the limit of self-load.