• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1199-1213
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• 2011

Slurry type shield would be very effective for the tunnelling in a sandy ground, but low slurry pressure could cause a tunnel face failure or a ground settlement in front of the tunnel face. Thus, the stability of tunnel face could be maintained by applying an excess slurry pressure that is larger than the active earth pressure. However, the slurry pressure should increase properly because an excessively high slurry pressure could cause the slurry flow out or the passive failure of the frontal ground. It is possible to apply the high slurry pressure without passive failure if a horizontal impermeable layer is located in the ground in front of the tunnel face, but its location, size, and effects are not clearly known yet. In this research, two-dimensional model tests were carried out in order to find out the effect of a horizontal impermeable layer for the slurry shield tunnelling in a saturated sandy ground. As results, larger slurry pressure could be applied to increase the stability of the tunnel face when the impermeable layer was located in the ground above the crown in front of the tunnel face. The most effective length of the impermeable grouting layer was 1.0~1.5D, and the location was 1.0D above the crown level. The safety factor could be suggested as the ratio of the maximum slurry pressure to the active earth pressure at the tunnel face. It could also be suggested that the slurry pressure in the magnitude of 3.5~4.0 times larger than the active earth pressure at the initial tunnel face could be applied if the impermeable layer was constructed at the optimal location.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.4
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• pp.347-370
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• 2011

Slurry type shield would be very effective for the tunnelling in a sandy ground, when the slurry pressure would be properly adjusted. Low slurry pressure could cause a tunnel face failure or a ground settlement in front of the tunnel face. Thus, the stability of tunnel face could be maintained by applying an excess slurry pressure that is larger than the active earth pressure. However, the slurry pressure should increase properly because an excessively high slurry pressure could cause the slurry flow out or the passive failure of the frontal ground. It is possible to apply the high slurry pressure without passive failure if a horizontal impermeable layer is located in the ground in front of the tunnel face, but its location, size, and effects are not clearly known yet. In this research, two-dimensional model tests were carried out in order to find out the effect of a horizontal impermeable layer for the slurry shield tunnelling in a saturated sandy ground. In tests slurry pressure was increased until the slurry flowed out of the ground surface or the ground fails. Location and dimension of the impermeable layer were varied. As results, the maximum and the excess slurry pressure in sandy ground were linearly proportional to the cover depth. Larger slurry pressure could be applied to increase the stability of the tunnel face when the impermeable layer was located in the ground above the crown in front of the tunnel face. The most effective length of the impermeable grouting layer was 1.0 ~ 1.5D, and the location was 1.0D above the crown level. The safety factor could be suggested as the ratio of the maximum slurry pressure to the active earth pressure at the tunnel face. It could also be suggested that the slurry pressure in the magnitude of 3.5 ~4.0 times larger than the active earth pressure at the initial tunnel face could be applied if the impermeable layer was constructed at the optimal location.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.5
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• pp.391-397
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• 2002

Pressure drop were experimentally investigated for ice slurry flowing in the acrylic pipes with inner diameter of 24 mm. Ice slurry was made from 6.5% ethylene glycol-water solution, and the pipes is consisted of horizontal, vertical (upward and downward) and $90^{\circ}$ elbow pipe. The ice Packing factor (IPF) and the flow rate of the experiments were varied from 0 to 30% and from 5 to 70kg/min respectively The measured pressure drop in various pipe positions were compared with those for the solution flow (IPF=0). The pressure drop was larder than that for solution flows as the IPF increased when the flow rate was low or very high. Sharp increases in pressure drop were observed for the cases when IPF is more than 70% in horizontal and vertical pipes, whereas the pressure drop increased with the IPF simultaneously in an elbow pipe.

• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.829-832
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• 2006

In this study, the influence of the magnetic field on ferrite slurry's injection time during the slurry forming process was investigated. The evaluation system of the slurry's injection time under the strong magnetic field was designed with FEM and manufactured. Studied parameters were the applied magnetic field, the input pressure of the slurry, and the supplying tube materials. As the results, the injection time was increased with the external magnetic field strength and rapidly decreased with increasing the input pressure of the slurry. Also the injection time was decreased when the supplying tube was manufactured with the magnetic material having the higher magnetic permeability than the ferrite.

• Bulletin of the Korean Chemical Society
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• v.22 no.2
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• pp.159-163
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• 2001

Si3N4 powder has been analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). The sample was dissolved by high-pressure acid digestion with HF, H2SO4 (1+1), and HNO3 mix ture. This technique is well suited for the impurity analysis of Si3N4 because the matrix interference is eliminated. A round-robin samples trace elements, such as Ca, W, Co, Al, Fe, Mg, and Na, were determined. For the direct analysis, slurry nebulization of 0.96 mm Si3N4 powder also has been studied by ICP-AES. Emission intensities of Fe were measured as ICP operational conditions were changed. Significant signal difference between slurry particles and aqueous solution was observed in the present experiment. Analytical results of slurry injection and high-pressure acid digestion were compared. For the use of aqueous standard solution for calibration, k-factor was determined to be 1.71 for further application.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.4
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• pp.478-486
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• 2007

Numerical analysis had been performed to understand flow characteristics of the flue gas and slurry in the absorber of a flue gas desulphurization (FGD) system using computational fluid dynamics (CFD) technique. Two-fluid(Euler-Lagrangian) model had been employed to simulate physical phenomenon, which slurry particles injected through slurry spray nozzles fall down and bump into the flue gas inflowing through inlet duct. It was not necessary to adopt pre-defined pressure drop inside the absorber because interaction between flue gas and slurry particles was considered. Hundreds of slurry spray nozzles were considered with the spray velocity at the nozzles, swirl velocity and spreading angle. The results note that the flow disturbance of flue gas is found at the bottom of the absorber, and the current rising with high speed stream is observed in the opposite region of the inflow duct. The high speed stream is reduced as the flue gas goes up, because the high speed stream of flue gas dumps falling slurry particles due to momentum exchange between flue gas and slurry particles. In spite of some disproportion in slurry distribution inside the absorber, escape of slurry particles from the absorber facility is not observed. The pressure drop inside the absorber is mainly occurred at the bottom section.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.528-532
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• 2013

Well-dispersed slurries of submicron-sized alumina powders were pressure-infiltrated in 3D preforms of mullite fibers and the effects of the particle size and infiltration pressure on the particle packing characteristics were investigated. Infiltration without pressure showed that the packing density increased as the particle size decreased due to the reduction of the friction between the particles and the fibers. The infiltrated preforms contained large pores in the large voids between the fiber tows and small pores in the narrow voids between the individual fibers. Pressure infiltration resulted in a packing density of 77% regardless of the particle size or the infiltration pressure(210 ~ 620 kPa). Pressure infiltration shortened the infiltration time and eliminated the large pores in preforms infiltrated with the slurries of smaller particles. The slurry pressure-infiltration process is thus an efficient method for the packing of matrix materials in various preforms.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.2
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• pp.272-279
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• 2003

This study aimed to understand the effects of transporting ice slurry Particles through Pipes with branches. The experimental apparatus was constructed as ice slurry mixing tank. vortex pump, manometers for differential pressure measuring. IPF(ice packing factor) measuring instruments and branches as test sections. The experiments were carried out under various conditions. with concentration of water solution ranging between 0∼20wt% and velocity of water solution at the entry ranging between 1.5∼2.5m/s. The differential Pressure and IPF between the pipe entry and exit were measured. and flowing form was checked throughout the experiment. The pressure loss in 3d branches appeared compared with 6d branches so that it was very high. In the pressure loss of the inside and outside of branches. 6d branches was showed the difference. but was agreed in 3d branches The pressure loss according to concentration of water solution, low value appeared at 10wt% in 6d branches, at 20wt% in 3d branches. The pressure loss according to velocity, did not show large difference. The change of IPF at outlet, appeared +15∼-25% in 6d branches and 0∼-20% in 3d branches. The difference of IPF at the inside and outside of branches. appeared 10∼15% in 6d branches and maximum 5% in 3d branches.

• Journal of the Korean Society for Railway
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• v.16 no.1
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• pp.47-51
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• 2013

In this study, we carried out an experimental shield TBM excavation model test using a down-scale device in soft clay, to understand tunnel-face stability properties in relation to changes in slurry pressure. We performed five tests according to tunnel depth (0.5D, 0.75D, 1.0D, 1.25D, 1.5D), and compared theoretical tunnel-face pressure with model test results. The range in theoretical tunnel-face slurry pressure ($P_{min}{\leq}P_{slurry\;pressure}{\leq}P_{max}$), which is determined by earth pressure and water level, was very similar to the model test result. This result was due to the more isotropic condition of the soft clay ground, than of rocky ground.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.160-163
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• 2001

In order to develop a nodule conveying system through a flexible pipe out of the deep-seabed manganese nodule miner, an experimental study of the solid-water slurry flow in vertical pipe is performed as the first stage of total experiments. Hydraulic characteristics of the pipe slurry flow such as slip velocity, transport concentration and pressure gradient are investigated for the size of particle, load ratio, and flow rate of water. The higher the load ratio is, the larger the transport concentration and pressure gradient become. The bigger the size of particles is, the larger the pressure gradient becomes. The effectiveness of the flow rate to hydraulic performance is also investigated. This results are to be used for designing crusher and pump, and operating the conveying device.