• Geomechanics and Engineering
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• v.18 no.1
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• pp.97-109
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• 2019

Physical conditions play vital role on the mechanical properties of frozen soil, especially for the temperature and moisture content of frozen soil. Subsequently, they influence the subsidence and stress law of permafrost layer. Taking Jiangcang No. 1 Coal Mine as engineering background, combined with laboratory experiment, field measurements and empirical formula to obtain the mechanical parameters of frozen soil, the thick plate mechanical model of permafrost was established to evaluate the safety of permafrost roof. At the same time, $FLAC^{3D}$ was used to study the influence of temperature and moisture content on the deformation and stress law of frozen soil layer. The results show that the failure tensile stress of frozen soil is larger than the maximum tensile stress of permafrost roof occurring in the process of mining. It indicates that the permafrost roof cannot collapse under the conditions of moisture content in the range from 20% to 27% as well as temperature in the range from $-35^{\circ}C$ to $-15^{\circ}C$. Moreover, the maximum subsidence of the upper and lower boundary of the overlying permafrost layer decreases with the increase of moisture content in the range of 15% to 27% or the decrease of temperature in the range of $-35^{\circ}C$ to $-15^{\circ}C$ if the temperature or moisture content keeps consistent with $-25^{\circ}C$ or 20%, respectively.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.51-52
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• 2006

This study was progressed on the freezing behavior of waste water in relation to freeze concentration method useful to waste water treatment system of small and middle size and which can re-use purified water. The object of this experiment is comparing a pollutant contain of the frozen layer and of an aqueous solution by cooling wall temperature, a flow field effect and a initial thickness of frozen layer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.474-479
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• 2005

Experimental and theoretical studies of internal cavity pressure during injection molding of a spiral tube cavity were carried out. The frozen layer thickness and the evolution of internal cavity pressure were calculated using a commercial software (C-MOLD). The evolution of the internal cavity pressure was recorded during injection molding of polystyrene into a spiral tube mold. To explain the differences observed between the calculated and measured internal cavity pressure, a pressure correction factor (PCF) was introduced based on the plane stress theory. This factor was determined by analyzing the stress state in the melt and calculating the frozen layer thickness near the mold wall. The corrected and experimental pressures have been compared to validate the applicability of the pressure correction factor.

• Geomechanics and Engineering
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• v.15 no.2
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• pp.783-791
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• 2018

In consideration of the mesoscopic structure of soil-rock mixtures in which the rock aggregates are wrapped by soil at normal temperatures, a two-layer embedded model of single-inclusion composite material was built to calculate the shear modulus of soil-rock mixtures. At a freezing temperature, an interface ice interlayer was placed between the soil and rock interface in the mesoscopic structure of the soil-rock mixtures. Considering that, a three-layer embedded model of double-inclusion composite materials and a multi-step multiphase micromechanics model were then built to calculate the shear modulus of the frozen soil-rock mixtures. Given the effect of pore structure of soil-rock mixtures at normal temperatures, its shear modulus was also calculated by using of the three-layer embedded model. Experimental comparison showed that compared with the two-layer embedded model, the effect predicted by the three-layer embedded model of the soil-rock mixtures was better. The shear modulus of the soil-rock mixtures gradually increased with the increase in rock regardless of temperature, and the increment rate of the shear modulus increased rapidly particularly when the rock content ranged from 50% to 70%. The shear modulus of the frozen soil-rock mixtures was nearly 3.7 times higher than that of the soil-rock mixtures at a normal temperature.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.6
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• pp.1250-1259
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• 2001

This study was experimentally performed to investigate sea water freezing behavior along parallel cooled plate with bubbly flow The experiments were carried out for a variety of parameter, such as sea water velocity, air-bubble flow rate, and cooled-plate temperature. The shape of freezing layer, freezing rate and salinity of frozen layer were observed and measured. It was found that the experimental parameters gave a great influence on the freezing rate and the salinity of the frozen layer.

• Journal of the Korean Geotechnical Society
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• v.30 no.10
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• pp.67-80
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• 2014

The thickness of permafrost in Eastern Siberia is from 200 to 500 meters. The seasonally frozen layer can vary from 0 to 4m depending on ground temperature and its location. The shear wave velocity varies from 80m/s in summer to 1500m/s in winter depending on soil type. When melted, large impedence will occur due to the difference between the shear wave velocity of seasonally frozen soil and that of permafrost layer. Large displacement may occur at the boundary of the melted and the frozen layer, and this phenomenon should be considered in a seismic design. In this research, one-dimensional equivalent linear analyses were performed to investigate the effects of the seasonally frozen layer on ground amplification characteristics. Soil profiles of Yakutsk and Chara in Eastern Siberia were selected from geotechnical reports. 20 recorded ground motions were used to evaluate the effect of input motions. As the thickness of seasonally frozen layer and the difference in the shear wave velocity increases, the amplification is shown to increase. Peat, very soft organic soil widely distributed throughout Eastern Siberia, is shown to cause significant ground motion amplification. It is therefore recommended to account for its influence on propagated motion.

• Geomechanics and Engineering
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• v.10 no.2
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• pp.225-245
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• 2016

Settlement of foundations in permafrost regions primarily results from three physical and mechanical processes such as thaw consolidation of permafrost layer, creep of warm frozen soils and the additional deformation of seasonal active layer induced by freeze-thaw cycling. This paper firstly establishes theoretical models for the three sources of settlement including a statistical damage model for soils which experience cyclic freeze-thaw, a large strain thaw consolidation theory incorporating a modified Richards' equation and a Drucker-Prager yield criterion, as well as a simple rheological element based creep model for frozen soils. A novel numerical method was proposed for live computation of thaw consolidation, creep and freeze-thaw cycling in corresponding domains which vary with heat budget in frozen ground. It was then numerically implemented in the FISH language on the FLAC platform and verified by freeze-thaw tests on sandy clay. Results indicate that the calculated results agree well with the measured data. Finally a model test carried out on a half embankment in laboratory was modeled.

• Tunnel and Underground Space
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• v.11 no.4
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• pp.362-367
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• 2001

The stiff top layer in a soil profile, which can happen in winter, may change the isolation effect of the wave barrier. The research scope of this paper is the investigation of the propagation of surface waves in layered soil with a stiff layer on its top, and the isolation effect of the solid stiff wave barrier. The investigations have been performed numerically by the Boundary-Element Method as a two-dimensional problem. A strip foundation vibrated harmonically in vertical direction was considered as the vibration source. Three soil profiles, a homogeneous half-space, two profiles with different thickness of stiff top layer, with two different types of wave barriers were investigated. The profiles with a stiff top layer show considerable reductions of the amplitude of the vibration in comparison to the homogeneous soil profile. The layered soil profiles with a stiff top layer do not show wave propagation velocities as high as they are expected from the material properties. Furthermore the vibration amplitudes in a frozen soil are much smaller with distance than in a non-frozen soil.

• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.129-135
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• 2013

Recently, waste water treatment system is developed in small and middle size to get more economic advantage. Freeze concentration system has high thermodynamic efficiency and low energy consumption, can re-use purified water and cold energy obtained from ice. This study was experimentally performed to investigate pollution containment in frozen layer by cooling wall temperature, air-bubble flow methods, initial ice-lining thickness of frozen layer in NaCl aqueous solution and the representative heavy metals, Pb and Cr aqueous solution. As the result, a decrease in the cooling wall temperature bring a higher growth rate of ice front and the more solute was involved in frozen layer. The method to inject directly air-bubble into ice-liquid interface through ring shape nozzle gave high purity of ice compared to indirect method. Ice lining in 5mm thickness resulted in frozen layer with higher purity than 1mm thickness.

• Korean Journal of Agricultural Science
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• v.48 no.4
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• pp.739-751
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• 2021

The thawing process is usually essential for imported pork because this product is typically distributed frozen. Consumers prefer fresh pork because discoloration, nutrient spills, and microbial contamination are high during the thawing process. The illegal act of selling frozen pork by disguising it as fresh pork through various methods can occur for the benefit of the difference in the sales price. However, there is some difficulty in securing systematic and objective data, as sensory tests are generally performed on imported pork. In the experiment conducted here, the electrical conductivity and dielectric properties of pork neck and pork belly products were measured. The amounts of change before and after freezing were compared through a statistical analysis, and a new method for determining frozen meat was proposed based on the analysis results. The weight was reduced compared to that before freezing due to the outflow of drips from the thawing process, but there was no difference in the drip loss level due to the thawing method. Vacuum packaging was found to lead to more drip loss than regular packaging, but the difference was not statistically significant. Frozen pork neck meat can be determined by measuring the electrical conductivity in the lean parts and the dielectric characteristic in the fatty parts. Frozen pork belly is determined by measuring the dielectric constant of the part closest to the outer fat layer.