• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1750-1756
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• 2011

This study evaluated the effect of antioxidants treatment; (Vit. C and E) on the physicochemical and sensory properties of Tarakjuk treated with gamma-irradiation under two different temperature conditions, e.g. room and frozen temperatures. In samples of Tarakjuk irradiated at room temperature, Vit. C gradually decreased the pH level as the concentration increased (p<0.05), whereas Vit. E did not. Addition of both Vit. C and E to Tarakjuk decreased TBA (2-thiobarbituric acid) value while also increasing viscosity. However, these antioxidants did not cause any change in Hunter's color values. Sensory properties showed that Vit. C and E significantly improved the overall acceptability of Tarakjuk, and the addition of 0.1% each Vit. C and E was best treatment. In samples of Tarakjuk subjected to combined treatment with antioxidants and irradiation under frozen temperature conditions, Vit. C and E were effective in decreasing TBA value, improving viscosity, and maintaining sensory quality. Especially, co-treatment with 0.1% Vit. C and E augmented the observed effect (p<0.05). Therefore, combined treatment with antioxidants and irradiation under frozen temperature conditions could improve the final sensory quality of gamma-irradiated Tarakjuk.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.67-72
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• 2005

To investigate the feasibility of a new concept of storing Liquefied Natural Gas (LNG) in a lined hard rock cavern, and to develop essential technologies for constructing underground LNG storage facilities, a small pilot plant storing liquid nitrogen (LN2) has been constructed at the Korea Institute of Geoscience and Mineral Resources (KIGAM). The LN2 stored in the cavern will subject the host rock around the cavern to very low temperatures, which is expected to cause the development of an ice ring and the change of ground condition around the storage cavern. To investigate and monitor changes in ground conditions at this pilot plant site, geophysical, hydrogeological, and rock mechanical investigations were carried out. In particular, geophysical methods including borehole radar and three-dimensional (3D) resistivity surveys were used to identify and monitor the development of an ice ring, and other possible changes in ground conditions resulting from the very low temperature of LN2 in the storage tank. We acquired 3D resistivity data before and after storing the LN2, and the results were compared. From the 3D images obtained during the three phases of the resistivity monitoring survey, we delineated zones of distinct resistivity changes that are closely related to the storage of LN2. In these results, we observed a decrease in resistivity at the eastern part of the storage cavern. Comparing the hydrogeological data and Joint patterns around the storage cavern, we interpret this change in resistivity to result from changes in the groundwater flow pattern. Freezing of the host rock by the very low temperature of LN2 causes a drastic change in the hydrogeological conditions and groundwater flow patterns in this pilot plant.

• Korean Journal of Animal Reproduction
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• v.23 no.3
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• pp.247-256
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• 1999

The present study was performed to improve the reproductive disturbance as well as the elimination of microbiological contamination for animals bred under conventional conditions followed by in vitro fertilization and embryo transfer techniques including embryo and sperm freezing, using a mouse strain(M. m. molossinus-tt＠Kist) showing the abnormal behavior disorder derived from Korean wild mice (Mus musculus molossinus). Moreover, hematological and serum biochemical analyses were also carried out to obtain the basic data of this mouse strain The results are summarized as follows: 1. In comparison with hematological data, the numbers of RBC and platelet of this mouse strain were appeared as the higher value those that of the same aged inbred strains such as BALB/c, DBA/2, C57BL/6 and C3H /Hen. However, no differences were found in values of WBC, Hb and Ht. Moreover, total cholesterol of this strain showed a low value but triglyceride, total protein and albumin values were similar as in inbred strains. 2. The average numbers of superovulated oocytes treated with 2.5/2.5 IU and 5.0/5.0 IU of PMSG/hCG were 11.6 and 12.7, respectively. The fertilization rates of 2.5/2.5 IU PMSG /hCG treatment(87.9%) was higher than 5.0/5.0 IU treatment(52.0%) (p＜0.05) and the developmental rate of 2 cell stage embryos were 외 so appeared as higher value 99.0% and 90.6%, respectively. 3. The rates of in vitro fertilization treated with frozen sperm(24.8%) was significantly lower than of that fresh sperm(87.9%), (p＜0.05). 4. The five, six and ten heads of offspring were obtained from frozen-thawed 2 cell embryos by in vitro fertilized, 2 cell embryos from in vitro fertilized by frozen-thawed spermatozoa. and 2 cell embryos by in vitro fertilization, respectively. These offspring developed the expected disease about 2 weeks after birth, which was confirmed that the disease character of this mutant mouse strain was reliably reproduced. 5. MHV(Mouse hepatitis virus) and Staphylococcus aureus were successfully eliminated from conventional animals by in vitro fertilization-embryo transfer and the use of SPF recipient animals.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1529-1535
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• 1999

This study was done for the extraction of carotenoid from Phaffia rhodozyma in combination with PEF and other methods. PEF treatment conditions were $30{\sim}80\;kV/cm,\;100{\sim}1000\;Hz\;and\;100{\sim}1000\;{\mu}s$. In order to increase permeability of yeast cell wall, various methods such as freezing-thawing, mechanical treatment, solvents, permeabilizing agents, and yeast cell wall lytic enzyme were used before PEF treatment. The combination of PEF $(50\;kV/cm,\;300\;Hz,\;1000\;{\mu}s)$ and conventional methods such as solvent and freezing-thawing pre-treatment had no effects on the extraction of carotenoid pigments. The extent of extracted carotenoid by the PEF $treatment(50\;kV/cm,\;300\;Hz,\;1000\;{\mu}s)$ combined with yeast cell wall lytic enzyme and mechanical pre-treatment increased 52% and 69.8% more than the sum of that by each treatment, respectively. Permeabilizing agents, especially Tween 20 and capric acid, enhanced the extraction efficiency of carotenoid pigments from P. rhodozyma cells. These results indicated the feasibility for the continuous extracting carotenoid pigments from P. rhodozyma by PEF combined with other permeabilizing methods.

• Journal of the Korea Concrete Institute
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• v.20 no.1
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• pp.13-22
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• 2008

The initiation and growth processes of cyclic ice body in porous systems are affected by the thermo-physical and mass transport properties, as well as gradients of temperature and chemical potentials. Furthermore, the diffusivity of deicing chemicals shows significantly higher value under cyclic freeze-thaw conditions. Consequently, the disintegration of concrete structures is aggravated at marine environments, higher altitudes, and northern areas. However, the properties of cyclic freeze-thaw with crack growth and the deterioration by the accumulated damages are hard to identify in tests. In order to predict the accumulated damages by cyclic freeze-thaw, a regression analysis by the response surface method (RSM) is used. The important parameters for cyclic freeze-thawdeterioration of concrete structures, such as water to cement ratio, entrained air pores, and the number of cycles of freezing and thawing, are used to compose the limit state function. The regression equation fitted to the important deterioration criteria, such as accumulated plastic deformation, relative dynamic modulus, or equivalent plastic deformations, were used as the probabilistic evaluations of performance for the degraded structural resistance. The predicted results of relative dynamic modulus and residual strains after 300 cycles of freeze-thaw show very good agreements with the experimental results. The RSM result can be used to predict the probability of occurrence for designer specified critical values. Therefore, it is possible to evaluate the life cycle management of concrete structures considering the accumulated damages due to the cyclic freeze-thaw using the proposed prediction method.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.770-774
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• 2002

The effect of mixing ratio of materials and their retort processing conditions on the physical properties and preference of oyster porridge were investigated. Rice gave adequate viscosity (about 800 cp) to the porridge as it was used 10～12% level and half of it was ground. Potato starch, waxy corn starch, and Perfectamyl AC showed small variation in viscosity unrelated to the temperature, that was a good condition for high quality porridge. Especially, waxy corn starch had a good property for retort porridge because its viscosity was maintained high during the processing and decreased to preferable one after processing. Purity CSC, modified starch gave gum-like texture and didn't cause water-separation much after freezing and thawing treatment of the porridge. Therefore, it was good for enhancing the physical property of the porridge as a co-additive of waxy corn starch when it was used at quarter level of waxy corn starch. Xanthan gum increased dispersibility of materials and it was useful for stabilizing physical quality of the porridge without affecting preference when it was used below 0.2% concentration. As a result, the optimal material-mixing ratio was determined as rice 10% (50% of it was ground), waxy corn starch 1.5%, Purity CSC 0.5%, xmthan gum 0.2%, salt 0.3%, and water 87.5%. Oyster's porridge, retort processed with this recipe, showed stable physical property after 6 month storage at room temperature.

• Journal of Korean Society of Forest Science
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• v.78 no.1
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• pp.42-54
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• 1989

These studies were carried out to examine the anatomical, karyological characteristics, the variation of isozymes in needle and the frost damage of tissue for the purpose of investigating the relationships among the three natural Torreya nucifera populations of Cheju-do, Namhae, and Mt. Naejang in Korea. The results obtained can be summed up as follows : 1. The numbers of endodermal cells and inner layer cells of mucilage canal of needle conductive tissue were different in each population. The number of those of Cheju-do population was the largest. 2. In somatic chromosome, Namhae population showed one more secondary constriction. The values of $b^{arm}/a^{arm}$ were the same in all the three populations, but Cheju-do population particularly showed a different minimum value. And the karyotype formulas of each population showed difference. 3. During the meiosis, each population showed no significant difference in the irregular phenomena of chromosome. 4. In isoperoxidase and esterase variations of needle, each population showed its particular number and variation of bands. Cheju-do population showed the largest number and greatest variation of bands. 5. Under the same freeging conditions, the frost damage of Mt. Naejang population was comparatively slight, and Cheju-do population suffered from a greater frost damage than the others.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.4
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• pp.421-428
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• 2011

Thermal energy storage(TES) cooling system using cheaper electricity of off-peak time has been applied to relieve a significant portion of the peak demand of electricity during the daytime in summer. Slurry ice type thermal energy storage cooling system is one kind of more efficient ice-thermal energy storage cooling system than Ice-on-Coil type or Encapsulated type TES cooling system, even though, which are more popular TES system. This experimental study was carried out to observe flow pattern and formation of slurry ice in reversing flow layer to improve efficiency of heat transfer between fluid and freezing tube and to disturb ice adhesion on tube surface. The reversing flow layer was made by using reversing materials in heat exchanger section(test section) to disturb ice adhesion. At this experiment, styrofoam balls and poly propylene balls were used as reversing materials, and a 20wt% solution of ethylene glycol was used as reversing flow layer. The experimental apparatus was constructed of the test section for making/storing slurry ice, the brine tank, pumps for circulating of a 20wt% solution of ethylene glycol and brine, a flow-meter, a data logger for measuring the temperature. The experiments were carried out under various conditions, with volumetric flow rate, ball filling rate and air filling rate.

• Korean Journal of Agricultural Science
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• v.11 no.1
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• pp.94-102
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• 1984

These experiments were intended to obtain basic information to develop an effective method of seed storage, using local varieties of seeds of 13 different crops in Korea. The germination ratio and velocity were investigated at one month intervals with seeds stored in six different temperatures($-20^{\circ}C$, $-7^{\circ}C$, $7^{\circ}C$, $20^{\circ}C$, $30^{\circ}C$, $50^{\circ}C$) for six months. The results obtained are summarized as follows. 1. Final germination ratio of the seeds of different crops were not influenced by the storage temperatures when dry seeds were used, but moist seeds were affected by storage temperatures. 2. The germination velocity and growth of the primary root of the seeds were remarkably influenced by storage temperatures. Viability of the seeds maintained in freezing temperatures ($-20^{\circ}C$, $-7^{\circ}C$) and in low temperature ($7^{\circ}C$) were higher than that of the seeds stored in high temperature ($30^{\circ}C$).

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.163-170
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• 2012

With the advantage of a rapid exothermic reaction property, jet set concrete may be used as a cold weather concrete because it can reach the required strength before being damaged by cold weathers. And it can be hardened more quickly if the field temperature is properly compensated by heating. Because ordinary concrete cannot be hardened well under sub-zero temperatures, anti-freeze agents are typically added to prevent the frost damage and to ensure the proper hardening of concrete. While the addition of a large amount of anti-freeze agent is effective to prevent concrete from freezing and accelerates cement hydration resulting in shortening the setting time and enhancing the initial strength, it induces problems in long-term strength growth. Also, it is not economically feasible because most anti-freeze agents are mainly composed of chlorides. Recent studies reported that magnesia-phosphate composites can be hardened very quickly and hydrated even in low temperatures, which can be used as an alternative of cold weather concrete for cold weathers and very cold places. As a preliminary study, to obtain the material properties, mortar specimens with different mixture proportions of magnesia-phosphate composites were manufactured and series of experiments were conducted varying the curing temperature. From the experimental results, an appropriate mixture design for cold weathers and very cold places is suggested.