• Journal of the Korean Geotechnical Society
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• v.24 no.2
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• pp.67-75
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• 2008

It is interesting to note that distinct element method has been used extensively to model the response of micro and discontinuous behavior in geomechanics. Impressive advances related to response of distinct particles have been conducted and there were difficulties in considering fluid effect simultaneously. Current distinct element methods are progressively developed to solve particle-fluid coupling focused on fluid flow through soil, rock or porous medium. In this research, numerical simulations of fluid injection into particulate materials were conducted to observe cavity initiation and propagation using distinct element method. After generation of initial particles and wall elements, confining stress was applied by servo-control method. The fluid scheme solves the continuity and Navior-Stokes equations numerically, then derives pressure and velocity vectors for fixed grid by considering the existence of particles within the fluid cell. Fluid was injected as 7-step into the assembly in the x-direction from the inlet located at the center of the left boundary under confining stress condition, $0.1MP{\alpha}\;and\;0.5MP{\alpha}$, respectively. For each simulation, movement of particles, flow rate, fluid velocity, pressure history, wall stress including cavity initiation and propagation by interaction of flulid-paricles were analyzed.

• Resources Recycling
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• v.33 no.3
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• pp.48-56
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• 2024

In this study, physical property evaluation and physical separation of the target product were performed to investigate the possibility of using sewage sludge gasification solid residue (GSRs) as a circulating resource. Firstly, the GSRs used in this study was supplied by Sudokwon Landfill Management Corporation, and generally the GSRs was in the form of porous pellets with a particle size of several millimetres. In addition, the partially black areas were confirmed to be unburned and ungasified carbon, and the average carbon content was 5%. In addition, the content of silica, alumina and phosphorus oxide was more than 70% of the total content. It was confirmed that the metallic components of the wet grinding product were separated into individual elements. As a physical separation of metallic and non-metallic components was required, it was finally found that flotation screening was suitable. Accordingly, cationic and anionic surfactants were selected to separate metallic components in which a relatively large amount of non-metallic components were concentrated, and the separation characteristics were confirmed. As a result, it is expected that the concentration of non-metallic components such as silica, alumina and phosphorus will be easier than the separation of metallic components. Therefore, since it is possible to physically treat the gasified sludge residue, it is judged to have potential as a circular resource according to the proposed recycling method for the separated product.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.6
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• pp.422-429
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• 2013

It is generally known that the increase of the Earth surface temperature due to the global warming together with the land desertification by rapid urban development has caused severe climate and weather change. In desert or desertification land, it is observed that there are always severe flooding phenomena, even if desert sand has the high porosity, which could be believed as the favorable condition of rain water infiltration into ground water. The high runoff feature causes possibly another heavy rain by quick evaporation with the depletion of underground water due to the lack of infiltration. The basic physics of desert flooding is reasonably assumed due to the thermal buoyancy of the higher temperature of the soil temperature than that of the rain drop. Considering the importance of this topic associated with water resource management and climate disaster prevention, no systematic investigation has, however, been reported in literature. In this study, therefore, a laboratory scale experiment together with the effort of numerical calculation have been performed to evaluate quantitatively the basic hypothesis of run-off mechanism caused by the increase of soil temperature. To this end, first, of all, a series of experiment has been made repeatedly with the change of soil temperature with well-sorted coarse sand having porosity of 35% and particle diameter, 2.0 mm. In specific, in case 1, the ground surface temperature was kept at $15^{\circ}C$, while in case 2 that was high enough at $70^{\circ}C$. The temperature of $70^{\circ}C$ was tested as this try since the informal measured surface temperature of black sand in California's Coachella Valley up to at 191 deg. $^{\circ}F$ ($88^{\circ}C$). Based on the experimental study, it is observed that the amount of runoff at $70^{\circ}C$ was higher more than 5% compared to that at $15^{\circ}C$. Further, the relative amount of infiltration by the decrease of the surface temperature from 70 to $15^{\circ}C$ is about more than 30%. The result of numerical calculation performed was well agreed with the experimental data, that is, the increase of runoff in calculation as 4.6%. Doing this successfully, a basic but important research could be made in the near future for the more complex and advanced topic for this topic.

• Korean journal of food and cookery science
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• v.14 no.3
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• pp.225-231
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• 1998

Enzyme-treated glutinous rice flour, which was developed to shorten or skip a steeping process during the preparation of Yukwa, was analyzed for its physicochemical characteristics and compared with glutinous rice flour made by 28-day-steeping method. Total sugar content of the 28-day-steeped flour was the highest among all groups, on the other hand, the reducing sugar content was higher in enzyme-treated glutinous rice flour. The viscosity of enzyme-treated flours was significantly lower than that of the 28-day-steeped and particularly showed the lowest value at 65$^{\circ}C$. The contents of Ca$\^$2+/ and Mg$\^$2+/ in enzyme-treated glutinous rice flours were higher than those of the 28-day-steeped group, however, the content of P$\^$+/ was lower. Free sugar detected in glutinous rice flour prepared from 28-day-steeping method was glucose only, but enzyme-treated flours contained maltose and glucose, and the content of total free sugar was much higher than that of the 28-day-steeped group. In microscopic structure, both 28-day-steeped and enzyme-treated flours showed the particle size decreased and porous surface on some part of the flour granule.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.498-506
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• 2019

This study is based on a coating method that provides utilization value as a micronised powder for cosmetic raw materials using natural minerals buried in Bonghwa, Gyeongsangbuk-do in Korea. The mineral powder name is called Buseok, and chemical name is pumice powder. The results of a study on the efficacy of cosmetics are reported by the development of particulate powder to assess the performance of this powder. First of all, in order to coat the surface of this powder with oil, aluminum hydroxide was coated on the particulate surface and then coated with alkylsilan. In addition, it was coated with vegetable oil to prevent condensation of the powder and increase the dispersion in the oil phase. First; the particle size of pumice powder was from 10 to 50mm having porous holes on the surface of the particles. Second; The components of this powder contained $SiO_2$, $Al_2O_3$, $Fe_2O_3$, MgO, CaO, $K_2O_2$, $Na_2O$, $TiO_2$, $TiO_2$, MnO, $Cr_2O_3$, $V_2O_5$. Third: The particles of this powder have a planetary structure and are reddish-brown with porosity through SEM and TEM analysis. Fourth; the far-infrared radiation rate of this parabolic powder was $0.924{\mu}m$, and the radiative energy was $3.72{\times}102W/m^2$ and ${\mu}m$. In addition, the anion emission is 128 ION/cc, which shows that the coating remains unchanged. Based on these results, it is expected to be widely applied to basic cosmetics such as BB cream, cushion foundation, powderfect, and other color-coordinated cosmetics, sunblock cream, wash-off massage pack as an application of cosmetics. (Small and Medium Business Administration: S2601385)