• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 1997.11a
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• pp.141-141
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• 1997

• Journal of the Korean Geotechnical Society
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• v.33 no.8
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• pp.17-27
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• 2017

Gangwon province which is located in northeast of Korea is the coldest region where average daily temperature is below zero during winter while the other regions are above zero. However, there have been insufficient researches on the insulation design and the effect of the insulation on the freezing damages, even though freezing damages were reported consistently in the lining of road tunnel during winter. In this study, to investigate the effect of insulations on the reduction of freezing damages, numerical analysis was performed considering geotechnical and meteorological characteristics in Gangwon province during winter. As a result, it was found that thickness of concrete and shotcrete in lining had negligible effect on the freezing depth while the insulation had significant effect on it. In addition, because the freezing depth is greatly affected by the thermal conductivity of the ground behind the lining in the period of cold weather, these effects should be considered in the estimation of the insulation thickness.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.3
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• pp.342-347
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• 2007

Physicochemical properties of onion powder as influenced by drying methods were investigated. Moisture contents of onion powder were 13.29%, 12.99%, and 10.78% for samples dried using hot-air dryer, freeze dryer, and vacuum dryer, respectively. There were no significant differences in crude fat, crude protein, and crude ash content (p>0.05) depending on the drying methods. Samples prepared by freeze drying showed a significantly higher L-value as compared with those prepared by hot-air and vacuum drying (p<0.05). Scanning electron micrographs showed that freeze drying produced smaller particle-sized sample which in turn resulted in the higher porosity of the sample. Freeze dried samples revealed significantly lower degree of rehydration than other samples (p<0.05) probably due to small particle size of the sample. Water solubility of freeze dried sample appeared to be higher than that of other drying methods while the swelling ratio of the same sample appeared to be lower than that of the others. Browning index was significantly lower in samples prepared by freeze drying (p<0.05) but not significantly different between samples dried by hot-air and vacuum drying. Vitamin C content was higher in freeze dried onion powder due to the lower temperature applied to the sample. Freeze dried onion powder contained significantly lower amount of total polyphenol and higher amount of total sugar as compared to other samples (p<0.05).

• Journal of the Korean GEO-environmental Society
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• v.12 no.12
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• pp.79-88
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• 2011

Adfreeze bond strength develops upon freezing of pore water within soil and at foundation surface. It has been reported that various factors like temperature, soil type, and pile surface roughness affect adfreeze bond strength. Especially, pile surface roughness has been considered as a primary factor to design pile foundation in frozen ground. It has usually been estimated with fixed correction factors for pile materials. However, even if the pile foundation material is the same, the surface roughness could vary depending on the production circumstances. In this study, laboratory test was carried out to quantitatively analyze the effects of surface roughness on the adfreeze bond strength, and fractal dimension was used as a measure for surface roughness. Test results showed that adfreeze bond strength increased with decreasing temperature, increasing vertical stress and surface roughness. The adfreeze bond strength varies sensitively with surface roughness in the early freezing section of $-2^{\circ}C$, but its sensitivity decreased in the temperature ranging between $-2^{\circ}C$ to $-5^{\circ}C$. The results conclude that the roughness highly affects the frictional resistance of pile surface in frozen ground; however, the roughness does not affect considerably when the temperature drops below about $-2^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.19 no.2
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• pp.81-88
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• 1987

Rheological properties of rehydrated suspensions of two kinds of freeze dried Kochujang powders, processed at different freezing rates, were compared with raw Kochujang using Brookfield wide-gap rotational viscometer at $25^{\circ}C-60^{\circ}C$. Shear rates ranged from $0.1965\;sec^{-1}$ to $1.9650\;sec^{-1}$ and solid content ranged from 47% to 56%. Rehydrated suspensions of quickly frozen Kochujang powder and slowly frozen Kochujang powder, and raw Kochujang exhibited pseudoplastic behaviors with yield stress and presented thixotropic properties which followed the second-order kinetic behavior proposed by Tiu. Suspensions of Kochujang powders exhibited considerably higher decaying rates than raw Kochujang. The dependency of the equilibrium structure parameter on the shear rate was weak, and there were no significant differences among the values of structure parameters of three samples. The temperature dependency of the apparent viscosity of Kochujang suspension was fully expressed by Arrhenius equation and activation energies of suspensions of quickly frozen Kochujang powder and slowly frozen Kochujang powder, and raw Kochujang were 2.21, 2.18, and 2.32 Kcal/g.mole respectively. Consistency indices of three samples increased with solid content and decreased with temperature. Flow behavior indices of three samples showed no considerable dependency on the temperature and solid content. There were no significant differences in the rheological properties between two Kochujang powders.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.297-306
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• 1999

In this research, the frost heave mechanism of the weathered tuff soil sampled from the area tying between Ulanbator and Beijing was studied. The frost heave tests were carried maintaining the constant temperature at both upper$(+5^{\circ}C)\; and\; lower(-5^{\circ}C)$ ends of the sample. Here, main emphasis is given on variation of the freezing point depression with the variation of applied overburden pressure. The expansion of ice lens and migration of the pore water towards freezing front were observed in the test. It was found that with the increase in overburden pressure there is decrease in heave rate and increase in the absolute value of a segregation-freezing temperature. Hence the equation between segregation-freezing temperature and overburden pressure could be suggested. Also the water content of the samples at the frozen side was shown to be higher than those at the unfrozen side. Similarly, the water at warmer part of the frozen tuff was found much higher than that of the cooler part.

• Journal of the Korean GEO-environmental Society
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• v.16 no.6
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• pp.31-38
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• 2015

Recently, the participation on the development of the natural gas pipeline in Russia as well as the recent construction of the second Korean Antarctic research station, the Jangbogo station provide the research interests on the behavior of the permafrost ground. To investigate the effect of fines on the mechanical responses of frozen sands, unconfined compression tests were performed on the frozen sands with 0, 5, 10 and 15% of fine contents at -5, -10 and $-15^{\circ}C$. The poorly graded (SP) Joomunjin sand and kaolinite, silt with low plasticity (ML) were used for the preparation of the frozen soil specimens. The mechanical responses of the tested soils were investigated via unconfined compression tests in the temperature controlled laboratory and analyzed in terms of peak unconfined compressive strength and secant modulus at 50% of the peak strength. As the fine contents increase, the unfrozen water contents increase and thus the strength and stiffness of frozen soils decrease. The increment of the stiffness and strength due to the temperature decrease vary with the fine contents.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.942-948
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• 2002

When fresh concrete is exposed to low temperature, the concrete may suffer frost damage due to freezing at early ages and the strength development may be delayed. One of the solution methods to resolve these problems is to reduce freezing temperature of concrete by the use of chemical admixture called Accelerator for freeze protection. In this study we Investigate the effect on the strength development of cement mortar using accelerator for freeze protection with the variable curing condition. As the result of this study, the mortar using accelerator for freeze protection show continuously the strength development in curing condition of -5$^{\circ}C$. And the compressive strength under variable temperature condition was higher than constant temperature condition in same maturity.

• Journal of the Korean GEO-environmental Society
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• v.18 no.1
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• pp.5-12
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• 2017

The damage of the tunnel lining on the cold regions can be represented by cracks and leaks caused by freezing of ground water. However, domestically, the relevant construction guidelines are not provided so far. Thus, in this research, the mechanical behavior and thermal conductivity of designated tunnel area are measured using instrumentation system installed in the lining concrete inside tunnels in order to analysis their behavior with regard to temperature variations. Previous research mainly focused on the effect of temperature on the tunnel lining based on the air and initial ground temperature at urban regions. Thus, this study analyzes effects of air temperature and initial ground temperature of designated tunnel area at the cold regions. The temperature of the groundwater at the backfill of the tunnel lining are analyzed to evaluate the heating element. Numerical analyses are performed to evaluate the heating element with regard to the various initial ground temperatures.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.5
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• pp.340-344
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• 1991

On heating and fleering food-stuffs, it is very important to obtain informations about thermophysical properties of fishes for designing of freezing and heating equipment and analyzing of physico-chemical reaction during storage. It is particularly necessary to measure denaturation enthalpy, temperature, latent heat of freezing, activation energy, enthalpy, entropy and free energy on freezing and heating rate. In this study, DSC was used to study effects of freezing and heating rate on thermophysical properties and denaturation temperature on scanning rate $2.5-10.0^{\circ}C/min$. On increasing scanning rate, denaturation temperature of protein and lipid incresed and freezing point, activation energy, enthalpy, entropy were decreased. In freezing process free energy of fishes were found to be $14.2-18.9 kcal/mol$.