• Korean Journal of Materials Research
• /
• v.34 no.10
• /
• pp.457-463
• /
• 2024

3D printing using ceramic powder to produce precision ceramic parts has been studied with various additive manufacturing methods. This study analyzed problems occurring in alumina additive manufacturing that uses digital light processing (DLP) as well as methods to address such problems. For efficient analysis, we have classified alumina additive manufacturing into three types according to the driving method of the build platform - lifting type (LT), tilting type (TT) of the vat, and blade movement type (BT). LT had a problem with detachment and cracking of the alumina green body. However, this could be prevented by carefully controlling the cure depth of the suspension slurry and the bonding force between layers and improving the material used for coating the vat. TT, which resulted in non-uniform alumina additive manufacturing, could be improved by modifying the bidirectionality of the axis and the fluidity of the highly viscous alumina suspension slurry. BT resulted in detachment of the specimen as well as non-uniform results, but this could be avoided by shortening the shifting distance of the alumina suspension when it is introduced to the build platform, and enabling effective spreading.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.407-426
• /
• 2008

The bentonite slurry has been used as the stabilize suspension for wet process bored pile construction in Thailand. The bentonite suspension has benefit on filtration in the sand layer, but it creates thick cake film along pile shaft and loose sedimentation at pile toe. The base grouting technique was widely used to rectify the soft base or loose sedimentation problem of bored pile. The base grouting technique was not increased only end bearing capacity, but was also more increase in skin friction capacity of the bored piles. The comprehensive researches on base grouting was carried out by installing PVC casing inside the shaft to allow the drilling through the pile base in order to collect the soil sample below the pile tip. The polymer based slurry recently was used to replace the bentonite slurry to overcome the thick cake film along pile shaft as well as loose sedimentation at pile toe. The extent research on polymer slurry by physical model was performed to verify the real behavior of polymer. The appropriate mixing ratio of polymer was proposed. The design skin friction coefficient, $\beta$ and end bearing coefficient, Nq, for sand layer base on fully instrumented tested pile were proposed. The application on remedial of the lose capacity bored pile with large displacement in Bangladesh was proposed and discussed.

• Journal of the Korean Ceramic Society
• /
• v.40 no.2
• /
• pp.167-171
• /
• 2003

CMP(Chemical Mechanical Planarization) slurry for STI process is made by mechanically synthesized$CeO_2$as abrasive. The abrasive can be stabilized by electrostatic or steric stabilization in aqueous slurry and steric stabilization is more effective for long-term stability. Blanket-type$SiO_2$and $Si_3N_4$ wafers are polished with CMP slurry containing$CeO_2$synthesized in 50$0^{\circ}C$ or $700^{\circ}C$. Removal rate and surface uniformity of$SiO_2$and$Si_3N_4$wafer and selectivity are influenced by synthetic condition of abrasive, suspension stability and pH of slurries.

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.04a
• /
• pp.78.2-78
• /
• 2003

• Journal of Korea Soil Environment Society
• /
• v.2 no.3
• /
• pp.23-30
• /
• 1997

The purpose of this study was to evaluate effects of solids content and mixing speed in treatment of petroleum hydrocarbon contaminated soils using a slurry-phase bioreactor. Performance results on slurry-phase bioremediation of diesel fuel contaminated soil were generated at the bench-scale level. The fate of TPH(Total Petroleum Hydrocarbon) was evaluated in combination with biological treatment. Abiotic and biotic fate of the TPH were determined using soil not previously exposed to compounds in diesel fuel. The reactor volume for given throughput can be reduced by maximizing the solids content. Applications of 50% and 20% solids content(dry weight basis) were showed a little difference(57.5% : 61.6%) in biological TPH removal rate each other. Mixing and particle suspension are critical to desorption and biological degradation. In this standpoint, this study was performed using two mixing speed. When the reactor was operated at 70rpm, it had a better result in the particle suspension and TPH removal rate than the reactor with mixer rotated at 20rpm. In the reactor applied 20rpm, it was resulted in failure of particle suspension.

• KSBB Journal
• /
• v.14 no.4
• /
• pp.445-451
• /
• 1999

Glutathione production was carried out using mixed cells of E. coli TG1/pDG7 $\alpha$ and bakers yeast in an Aerated Slurry Bioreactor. Glutathione-producing enzymes were stable for 34 hours, yielding 4.6 mM glutathione in suspension reaction. Glutahione production with high density mixed cells was studied as a function of flow rate in an Aereated Slurry Bioreactor. Glutathione concentration was higher than that in suspension reaction for 32 hours at the substrate feeding rate of 5.2 mL/hr with cell recycle in continuous Aerated Slurry Bioreactor. It was for 42 hours at 2.6 mL/hr and 22 hours at 5.2 mL/hr without cell recycle. Glutahione productivity was 25.7 mg/g wet $cell{\cdot}hr$ at the substrate feeding rate of 10.4 mL/hr with cell recycle, but 5.28 mg/g wet $cell{\cdot}hr$ at 5.2 mL/hr and 1.65 mg/g wet $cell{\cdot}hr$ at 2.6 mL/hr without cell recycle. Effective production time increased from 25 to 45 hours, by using a surfactant, tween 80. As a purfing gas, nitrogen was tested instead of air to avoid a possible oxidizing effect on glutathione-producing enzymes, resulting in the increase of effective production time to 40 hours.

• Korea-Australia Rheology Journal
• /
• v.16 no.3
• /
• pp.109-115
• /
• 2004

Comparisons in shear behaviour are made between aqueous suspensions of a laterite ore and aqueous suspensions of pure goethite ($\alpha$-FeOOH), following prior papers in which the rheologies of the two mineral suspensions were characterized individually. Drawing comparisons is appropriate because the ore sample was about 65% goethite and it was originally thought that the pure goethite might serve as a model of the more complex laterite. Viscosity measurements of the two suspensions show that, at the same solids fraction, the goethite suspensions were more viscous by an order of magnitude, even though the goethite particles had much smaller aspect ratios. Similarly, yield stresses for the goethite suspensions were at least an order of magnitude higher. The most significant difference was in transient behaviour. Time-dependent effects were investigated by subjecting a fluid to a step change or a ramp sequence in shear rate, and measuring the resulting shear stress over time. In most cases, transient behaviour could not be detected in the goethite suspensions, whereas stresses in the laterite suspensions relaxed over periods of order 10 seconds. The disparate results indicate that a goethite suspension is a poor model of a laterite slurry.

• Applied Chemistry for Engineering
• /
• v.33 no.3
• /
• pp.284-288
• /
• 2022

Polypropylene (PP) powder/cellulose nanofibers (CNF) 1 wt% slurry composites were prepared by filtering their suspension under reduced pressure and dried them in an oven followed by the use of a twin screw extruder. PP modified with side branches and polar groups was used. The side branches and polar groups were introduced into PP by using divinylbenzene and maleic anhydride (MAH), respectively. As a result of examining the dispersibility of CNF and the physical properties of the composite, it was confirmed that the composite prepared from PP powder/CNF 1 wt% slurry showed equal or higher levels in tensile and flexural strength as compared with those using the composite prepared from CNF powder.

• Journal of Mechanical Science and Technology
• /
• v.14 no.10
• /
• pp.1159-1167
• /
• 2000

Particles in liquid-solid suspension flow might enhance or suppress the rate of heat transfer and turbulence depending on their size and concentration. The heat transfer characteristics of liquid-solid suspension in turbulent flow are not well understood due to the complexibility of interaction between solid particles and turbulence of the carrier fluid. In this study, the heat transfer coefficients of liquid-solid mixtures are investigated using a double pipe heat exchanger with suspension flows in the inner pipe. Experiments are carried out using spherical fly ash particles with mass median diameter ranging from 4 to $78{\mu}m$. The volume concentration of solids in the slurry ranged from 0 to 50% and Reynolds number ranged from 4,000 to 11,000. The heat transfer coefficient of liquid-solid suspension to water flow is found to increase with decreasing particle diameter. The heat transfer coefficient increases with particle volume concentration exhibiting the highest heat transfer enhancement at the 3% solid volume concentration and then gradually decreases. A correlation for heat transfer to liquid-solid flows in a horizontal pipe is presented.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.1C
• /
• pp.1-5
• /
• 2010

The river maintenance processing has revealed that the river beds in Korea have been significantly polluted in various ways for the last two decades. Thus, the dredging, transportation and landfilling of these contaminated materials are attracting public attention these days. In this study, electrokinetic method was applied in order to accelerate the settling processes of clay particles in suspension and evaluate the factors affecting the settling behaviour. It has been found from the testing results that the settling velocity under the influence of electrokinetics was much faster than the gravitational one, and the water content of slurry soil reduced significantly after the electrokinetic processing. The initial water content of slurry soil should be one of the important factors affecting the settling behaviour as well as variation of water content, and hence the electrokinetic processing would be the cost-effective method for the field application.