• Tribology and Lubricants
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• v.15 no.1
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• pp.46-51
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• 1999

An analytical model about lateral crack occurring in abrasive wear of brittle solids is developed. Stress field around the lateral crack and stress intensity factor at the crack tip are analytically modeled. Abrasive wear by abrasive particle is experimentally studied. In soda-lime glass, it is observed that chipping by lateral crack occurs and produces the greatest material removal when normal load applied by the abrasive particle is about 1.5∼3.0 N. The prediction of lateral crack length from the model is compared with the experimentally measured length in soda-lime glass.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.221-222
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• 2003

Typically, closed production system units are subject to an accumulation of fine suspended solids and dissolved organics (Weeks et at., 1992). Foam fractionation process is believed to be most effective in marine application for solids removal. In present experiment, the performance of foam fractionator for removal of solids, protein, and other dissolved materials was evaluated at different foam overflow heights and air flow rates in a pilot-scale recirculating aquaculture system for culture of Korean rockfish. (omitted)

• Proceedings of the Optical Society of Korea Conference
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• 1997.08a
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• pp.90-90
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• 1997

• Structural Engineering and Mechanics
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• v.11 no.2
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• pp.221-236
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• 2001

A local point interpolation method (LPIM) is presented for the stress analysis of two-dimensional solids. A local weak form is developed using the weighted residual method locally in two-dimensional solids. The polynomial interpolation, which is based only on a group of arbitrarily distributed nodes, is used to obtain shape functions. The LPIM equations are derived, based on the local weak form and point interpolation. Since the shape functions possess the Kronecker delta function property, the essential boundary condition can be implemented with ease as in the conventional finite element method (FEM). The presented LPIM method is a truly meshless method, as it does not need any element or mesh for both field interpolation and background integration. The implementation procedure is as simple as strong form formulation methods. The LPIM has been coded in FORTRAN. The validity and efficiency of the present LPIM formulation are demonstrated through example problems. It is found that the present LPIM is very easy to implement, and very robust for obtaining displacements and stresses of desired accuracy in solids.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.8
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• pp.1291-1297
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• 1997

Elastic-plastic finite element(FE) simulation was performed for polycrystalline solids subjected to plane strain tensile loading. Using Asaro's double slip crystal plasticity model, the polycrystalline solids were modeled by assigning different initial slip directions to each grain. From the FE calculations, the microscopic deformation characteristics of polycrystalline solids were analyzed. Moreover, the effect of grain size and grain boundaries on the deformation characteristics were clarified.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.2
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• pp.23-29
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• 2007

Fracture behavior of brittle solids such as rocks, ceramics and concrete is closely related to microcracking. A meso-scale analysis method using the natural element method is proposed for the analysis of material damage of brittle microcracking solids. The microcracking is assumed to occur along Voronoi edges in the Voronoi diagram generated using the nodal points as the generators. The mechanical effect of microcracks is considered by controlling the material constants in the neighborhood of the microcracks. The proposed meso analysis method is applied to the simulation of the microcracking behaviors of brittle solids subjected to uniaxial and biaxial macrostress. The obtained results are in good agreement with the results by computational damage mechanics model. The validity of the proposed method has been demonstrated by these numerical examples.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.31-34
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• 2005

This article has investigated the spatial distribution of the solid particles in polymerization reactors using CFD analysis (FLUENT v. 6.2.1). The suspension of the solids in stirred reactors is affected by a number of parameters including particle diameter, vessel shape, impeller size, impeller speed, and rotating direction of stirrer. The degree of solids suspension in the vessel was quantified with a statistical average value, ${\sigma}^2$. The best stirring conditions were determined based on ${\sigma}^2$, which was found to depend on the vessel bottom shape.

• Water for future
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• v.25 no.2
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• pp.67-78
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• 1992

Several field surveys were conducted to investigate changes of water quality with time in a tidal river. Results indicated that nitrification process were dependent on the change of salinity and suspended solids concenttration. Therefore laboratory batch experiments were conducted, using suspended solids and sediment taken from a tidal river, to study the effect of salinity on nitrification and to estimate kinetic parameters of it in the tidal river. suspended solids and sediment were sampled at a point in the middle stream. Sediments were collect from the aerobic layer of mud. The change of nitrogen concentration with time was clearly explained with Monod groth model and kinetic parameters were obtained by curve fitting method. Changes in NH4-N, NO2-N, and NO3-N concentrations in the river ROKKAU with time were simulated well using Lagrangian reference frame and parameter values obtained in the laboratory tests. T도 mechanism of nitrification by suspended solids and sediment in a tidal river is shown to depend on tidal effects.

• Journal of the Korean Wood Science and Technology
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• v.35 no.5
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• pp.67-75
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• 2007

As a part of abating the formaldehyde emission of urea-formaldehyde (UF) resin adhesive by lowering formaldehyde to urea (F/U) mole ratio, this study was conducted to investigate properties of UF resin adhesive with different F/U mole ratios. UF resin adhesives were synthesized at different F/U mole ratios of 1.6, 1.4, 1.2, and 1.0. Properties of UF resin adhesives measured were non-volatile solids content, pH level, viscosity, water tolerance, specific gravity, gel time and free formaldehyde content. In addition, a linear relationship between non-volatile solids content and sucrose concentration measured by a refractometer was established for a faster determination of the non-volatile solids content of UF resin. As F/U mole ratio was lowered, non-volatile solids content, pH, specific gravity, water tolerance, and gel time increased while free formaldehyde content and viscosity were decreased. These results suggested that the amount of free formaldehyde strongly affected the reactivity of UF resin. Lowering F/U mole ratio of UF resin as a way of abating formaldehyde emission consequently requires improving its reactivity.

• Korean Journal of Microbiology
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• v.24 no.4
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• pp.385-388
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• 1986

In a study of the aerobic growth of Baker's yeast (Saccharomyces cerevisiae) on Maxon-Johnson medium (with glucose as substrate) solidified with kudzu root starch, it was observed that between 8 and 24 hour incubation. 10 and 12% solids stimulated greater cell production than did 6 and 8% solids. The concentration of solids also affected thd secretion of protein from the yeast cells with the highest content of extracellular protein at 10-24 hour incubation stimulated by 10% starch solids.