• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.783-788
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• 1995

Cooked rices were frozen at four different rates(3, 5, 7 and 12 hr) of maximum ice crystal formation zone and stored at $-20^{\circ}C\;and\;-70^{\circ}C$ for 3 months. Freezing rate, storage temperature and storage period all affected the degree of retrogradation of cooked rice. As the maximum ice crystal formation zone increased from 3 hrs to 12 hrs, the degree of retrogradation of cooked rice increased from 14.9% to 40.0%. Further retrogradation occurred during the freezing storage and cooked rice stored at $-20^{\circ}C$ retrograded faster than that held at $-70^{\circ}C$. The hardness and adhesiveness of frozen cooked rice thawed in $40^{\circ}C$ water were measured. Hardness of the frozen cooked rice was higher than that of non-frozen sample and was higher at lower freezing rate. However, the hardness of cooked rice decreased after 3 months of storage. On the other hand, the adhesiveness decreased during the freezing processing, and adhesiveness decreased more rapidly at a higher freezing rate. However, the adhesiveness of cooked rice increased after 3 months of the storage, and the level of decrease was higher at $-70^{\circ}C$ than at $-20^{\circ}C$. After 3 months of storage, ice crystal size of frozen cooked rice became larger by recrystalization than that of frozen sample prior to storage. Microstructure of cooked rice was damaged by ice crystal formation and its growth when observed by scanning electron microscope.

• Journal of the Korean Home Economics Association
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• v.42 no.1
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• pp.167-180
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• 2004

This study was carried out to investigate quality characteristics of chopped garlic stored at various temperature. Chopped garlic was stored at room temp.($25^{\circ}C$), refrigerator temp.($5^{\circ}C$) and frozen temp. ($-18^{\circ}C$) for 1, 2, 4, 8, 24, 48, 72 hours(room temp.) and 1, 3, 5, 7, 10, 15, 20, 30 days(refrigerator temp. and frozen temp.), respectively. Brown color, Hunter color value, vitamine C contents and flavor patterns by electronic noes of chopped garlic were measured. Fresh chopped garlic was used as control and garlic powder by hot air drying was used for comparisons. Brown color of chopped garlic increased with increasing storage time, and the intensity of that was reduced as following order such as chopped garlic stored at room temp., refrigerator temp. and frozen temp. Brown color of garlic powder was most dark amomg all the samples. The results of Hunter color value was consistent with then of brown color in chopped garlic, whereas those of garlic powder showed relatively low browning. Above results might be caused by the difference of measurement as only surface color was measured in Hunter color value unlike brown color. Vitamine C contents of chopped garlic decreased with increasing storage time, and in particular those stored at room temp. decreased markedly as retention of those stored at room temp. was 60％ of control after 1 day storage. Vitamine C retention of chopped garlic stored at refrigerator temp. was 78％ of control after 10 day storage and that stored at frozen temp. was 86％ of control after 30 day storage. At room temp., flavor pattern by electronic nose showed a difference between chopped garlic stored for 1hour and control, and showed occurrence of off odor after 1 day storage. Flavor pattern of garlic powder by electronic nose showed a mild flavor. Flavor patterns of chopped garlic stored at refrigerator temp. were similiar until 10 day storage, whereas those showed occurrence of volitile components after 15 day storage. Flavor patterns of chopped garlic stored at frozen temp. were similiar after 30 day storage, and especially those after 3 day storage were almost the same as control. Therefore it is desirable to store chopped garlic within 1 day at room temp. and within 10 days at refrigerator temp. And it is most desirable to store chopped garlic at frozen temp. as retention of quality characteristics was superior than other storage temp.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.413-418
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• 2002

The dough was frozen either before or after fermentation at the five different freezing and storage conditions. Although fermentation before freezing was effective for rapid freezing, it reduced bread volume of the dough frozen at both air freezer and liquid immersion freezer. Freezing at the air freezer set to $-70^{\circ}C$ took more time for freezing and resulted in lower bread volume than freezing at the immersion freezer set to $-20^{\circ}C$. Therefore, the freezing in the liquid immersion freezer was more effective to reduce the freezing time and increase the bread volume. At the liquid immersion freezer, the higher temperature was more effective than lower temperature. The doughs frozen in a liquid immersion freezer set to $-10^{\circ}C$ and fermented after de-frosting produced higher bread volume than control unfrozen dough. And also there was no significant difference in bread volume between the control unfrozen dough and the dough frozen in a liquid immersion freezer set to $-10^{\circ}C$, fermented before freezing and re-fermented after defrosting. The longer proof time and greater loaf volume obtained for the dough frozen and stored at the air freezer set to $-70^{\circ}C$. Therefore the optimum process for freezing the dough was freezing immediately after mixing, storing at $-10^{\circ}C$ in a liquid immersion freezer and fermented after defrosting.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2211-2216
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• 2007

Liquefied gas vaporizer means machine to vaporize the liquefied gas as liquid nitrogen($LN_2$), liquefied natural gas(LNG), liquid oxygen($LO_2$) etc. In the air type vaporizer, the frozen dew is also created by temperature drop (below 273 K) on vaporizer surface. This problem increases as the time progresses and humidity increases. In addition, the frozen dew gradually becomes frost deposit consequently, heat transfer through vaporizer decreases because frost deposit form adiabatic sheet. Because of this reason, recent vaporizer system is installed as parallel type, this vaporizer system needs more expensive installation costs and more space. This paper was investigated on the heat transfer characteristics of liquefied gas vaporizer with super low temperature and this paper was carried out the numerical about air heating vaporizer with super low temperature. The numerical analysis on the heat transfer was studied on the effect of geometric parameters of the vaporizer, which are length 1000 mm of 4fin75le type vaporizer. 4fin75le means number of fin is 4 and height of fin is 75 mm.

• Korean Journal of Veterinary Research
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• v.56 no.2
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• pp.85-89
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• 2016

We tested a set of conditions for obtaining optimal tissue quality in preparation for histology in samples of mouse brain. C57BL/6J mice were sacrificed and perfused with 4% paraformaldehyde, after which the brains were removed and dehydrated in 30% sucrose solution. The brains were then divided into four groups according to freezing temperature and usage of optimal cutting temperature (OCT) compound. Next, we stained the sectioned brain tissues with Harris hematoxylin and eosin Y and immunohistochemistry was performed for doublecortin. The best quality tissue was obtained at $-25^{\circ}C$ and by not embedding with the OCT compound. When frozen at $-25^{\circ}C$, the embedded tissue was significantly damaged by crystals, while at $-80^{\circ}C$ there were no meaningful differences between qualities of embedded- and non-embedded tissues. Overall, we identified a set of conditions to obtain quality frozen brain sections. Our developed protocol will help resolve matters associated with damage caused to sectioned brain tissue by crystal formation during freezing.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.670-680
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• 2022

Owing to the lack of a cold-chain distribution system, most seafood is generally distributed under room temperature conditions. However the degradation of freshness during the distribution process can lead to disputes between sellers and consumers. The most widely used method for low-temperature distribution for seafood includes packaging it with styrofoam boxes and cold packs. In this study, vacuum-packed frozen fillets of four fish species of [white meat (Paralichthys olivaceus and Sebastes schlegelii) and red meat (Scomber japonicus and Scomberomorus niphonius)] were placed in styrofoam boxes with cold packs. Thereafter, changes in chemical (including pH, volatile basic nitrogen, and trimethylamine), physical (odor intensity, hardness, and chewiness), and microbial (viable cell count) characteristics of the fillets were measured during storage at 25℃. To identify the suitable method of determining freshness during the room-temperature distribution, several factors were considered, which included significant difference verification, correlation coefficients, and economic efficiency (experimental cost and time). Volatile basic nitrogen, pH, odor intensity, and viable cell count are the most rapid and accurate freshness indicators for determining freshness of frozen fish fillets during.

• Journal of the Korean Society of Food Culture
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• v.21 no.4
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• pp.426-432
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• 2006

This study was conducted to investigate the changes in quality characteristics of frozen maesil according to thawing methods. The quality of maesil thawed in microwave oven was superior to those thaw in refrigerating temperature(5 $^{\circ}$) and in room temperature(25 $^{\circ}$). Drip loss of maesil thawed in microwave oven was 3.2${\pm}$0.2%. The total content of free sugars of maesil was 426.6 mg%, and 3% of them was decreased during thawing in microwave oven. The total content of organic acids was 5,297.2 mg%, and 2.5% of them was decreased during thawing in microwave oven. The total content of free amino acids was 281.4 mg%, and 2.1% of them was decreased during thawing in microwave oven. The principle ingredients of frozen maesil was stand for the lost contents of free sugar and a content loss of free organic acid and free amino acid were the fewest by thawing. Antioxidant effect for soybean oil and linoleic acid of maesil extract were expressd POV and TBA values. Antioxidative activity of fresh maesil extract was highest followed by maesil thawed in microwave oven, thawed in refreezing temperature (5$^{\circ}$)and room temperature (25$^{\circ}$)

• Korean Journal of Food Science and Technology
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• v.39 no.6
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• pp.663-668
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• 2007

This study evaluated the microbial, nutritional, and rheological changes in potatoes, during storage at room, low, and freezing temperatures for 6 months. No significant changes in total aerobic plate counts were observed for any of the samples in the assessment of microbiological quality changes. For the 4 types of frozen potatoes, yeasts and molds were not found until 24 weeks. The sugar contents of the potatoes stored at room and low temperature ($10^{\circ}C$) increased during the first 4 weeks of storage, but then decreased rapidly thereafter; while those in the frozen potatoes did not change significantly throughout the 48 weeks. The vitamin C, B1, and B2 contents of the potatoes stored at room and low temperature had decreased significantly after 4 weeks of storage, however, the levels in the frozen potatoes did not change rapidly. The weight, volume, and hardness of the frozen potatoes changed much less as compared to the potatoes stored at room and low temperature over the 48 weeks of storage. Finally, the cohesiveness of all the samples, except for the frozen mashed potatoes, did not change during storage.

• Journal of the korean academy of Pediatric Dentistry
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• v.8 no.1
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• pp.119-125
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• 1981

The Purpose of this study was to evaluate the effect of frozen slab mixing technique on physical property of zinc phosphate cement used in Korea. Standard consistency, setting time, film thickness, solubility of cement prepared in frozen slab and room temperature slab were tested. The obtained results were as follows. 1. Amount of powder required for standard-consistency for all cements tested could be increased. 2. Setting time for all cements tested could be decreased. 3. No significant difference in film thickness. 4. Solubility for all cements tested could be decreased.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.546-552
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• 2010

Seasonal frozen ground affects structural behavior in South Korea. Frost and heaving of seasonal frozen ground results in the critical damage of roadway, railroad, and buried pipeline. It has been widely used to substitute frost susceptible soils with granular soils. This paper presents experimental investigation on the effectiveness of soil-shredded tire and soil-expanded polystylene (EPS) mixtures to reduce frost depth and force around a buried pipeline. Experimental data such as measured temperature profile and the deformation of buried pipeline were carefully observed and provide the evidence of the effectiveness of soil mixtures.