• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.373-384
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• 2000

The goal of this paper is to develop a computational method to predict cancellous bone density distributions based upon continuum levels of volumetric strain. Volumetric strain is defined as the summation of normal strains, excluding shear strains, within an elastic range of loadings. Volumetric strain at a particular location in a cancellous structure changes with changes of the boundary conditions (prescribed displacements, tractions, and pressure). This change in the volumetric strain is postulated to predict the adaptive change in the bone apparent density. This bone remodeling theory based on volumetric strain is then used with the finite element method to compute the apparent density distribution for cancellous bone in both lumbar spine and proximal femur using an iterative algorithm, considering the dead zone of strain stimuli. The apparent density distribution of cancellous bone predicted by this method has the same pattern as experimental data reported in the literature (Wolff 1892, Keller et al. 1989, Cody et al. 1992). The resulting bone apparent density distributions predict Young's modulus and strength distributions throughout cancellous bone in agreement with the literature (Keller et al. 1989, Carter and Hayes 1977). The method was convergent and sensitive to changes in boundary conditions. Therefore, the computational algorithm of the present study appears to be a useful approach to predict the apparent density distribution of cancellous bone (i.e. a numerical approximation for Wolff's Law)

• Journal of Biomedical Engineering Research
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• v.26 no.2
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• pp.117-122
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• 2005

The elastic modulus and the apparent density of the trabecular bone were evaluated from spherical indentation tests and Computed Tomography (CT) and their relationship was quantified. The femurs were prepared for trabecular bone analysis. Embedded with respect to their anatomical orientation, the transverse planes of the trabecular bone specimens were scanned at 1㎜ intervals using a CT scanner. The metaphyseal regions of femurs were sectioned with a diamond-blade saw, producing 8㎜ cubes. Using a specially made spherical indentation tester, the cubes were mechanically tested in the anterior-posterior (AP), medial-lateral (ML), and inferior-superior (IS) directions. After determination of modulus from the mechanical testing, the apparent densities of the specimens were measured. The results showed that the IS modulus was significantly greater than both the AP and ML moduli with the AP modulus greater than the ML modulus. This demonstrated that orthogonality was a structural characteristic of the trabecular bone. The power relationship between the modulus and the apparent density was also found to be statistically significant.

• Journal of the Korean institute of surface engineering
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• v.28 no.2
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• pp.92-100
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• 1995

To increase the capacity of positive electrode materials for matching the high capacity negative electrode materials in alkaline rechargeable batteries, high-density nickel hydroxide powders were made through a continuous process from nickel sulfate reacted with ammonia and sodium hydroxidc. The effect of operating conditions on structure, shape, size distribution, apparent density and tap density of powders were investigated. Crystal structure of nickel hydroxide powder was hcp according to Bravais Lattice. The increase of mean residence time promoted the growth of (101) plane. The shape of powder was nearly spherical. Their size was in the range of $2~50\mu\textrm{m}$. The size distribution of the powders prepared was narrower than that of commercially obtained nickel hydroxide. Apparent density and tap density were 1.6~1.7g/cc and 2.0~2.1g/cc, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.8 s.173
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• pp.27-33
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• 2005

Polishing pads play an important role in chemical mechanical polishing(CMP) which has recently been recognized at the most effective method to achieve global planarization. In this paper, we have investigated CMP characteristics as a change of groove density of polishing pads. The parameter $(K_n)$ is proposed to estimate groove density of pad. The $K_n$ is defined as groove area divided by pitch area. As the groove density value increased, removal rate increased to some point and then gradually saturated in case of increasing the groove density excessively. In addition Within wafer non-uniformity(WIWNU) worse as groove density increased excessively, although WIWNU improved as groove density increased. Also the uniformity of temperature of pad surface decreased as the groove density increased. It was because that the cooling effect increased as groove density increased. In other words, increasing the groove density which means the apparent contact area of pad has influence on amount of discharge of slurry during polishing process.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.06a
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• pp.81-86
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• 1998

The light aggregates were fabricated by sintering green bodies made form the fly ash-clay alip. The content of fly ashes in the slip could be increased up to 70wt.% due to controlled rheological behavior of the slip, and the green body of uniform microstructure could be obtained by DCC(Direct Coagulation Casting)method. The apparent density, microstructure and compressive strength for sintered bodies fired at 1100∼1200$^{\circ}C$ were evaluated. The properties of light aggregates fabricated depend on slip density, particle behavior in the slip and sintering conditions. The sintered body prepared by firing a green body made from slip of density 1.60 at 1150$^{\circ}C$/2hr satisfied conditions of a light aggregate as apparent density of 1.49${\pm}$0.02 and compressive strength of 584${\pm}$62kg/$\textrm{cm}^2$.

• Journal of the Korean Ceramic Society
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• v.28 no.1
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• pp.37-45
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• 1991

The critical current density, electrical conductivity, critical magnetic field, Meissner effect, apparent density, and microstructure of YBa2Cu3O7-x ceramic superconductor prepared by polymeric precursor, while varing calcining and sintering conditions, were investigated. The best superconducting properties could be obtained from the body sintered at 93$0^{\circ}C$ for 10h after calcining at 90$0^{\circ}C$ for 10h, which gave 383A/$\textrm{cm}^2$ of critical current density(Jc), 96K of onset temperature(Tonset), 94. 8K of zero temperature (Tzero) 225 Oe of critical magnetic field (Hc1), 72.8% of superconducting volume fraction measured by Meissner effect and 6.28g/㎤ of apparent density.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.45-46
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• 2023

CLC is used as a filling material for many buildings, and according to energy saving design standards, CLC also requires insulation performance. However, it shows lower insulation performance compared to organic insulation, so additional research is needed. Therefore, in this study, the insulation properties of CLC were analyzed by incorporating EPS beads with high insulation performance into CLC. In this experiment, EPS beads and blast furnace slag were replaced, and W/B was fixed at 33%. The EPS Bead mixing ratio was divided into 5 levels: 0, 0.5, 1.0, 1.5, 2.0 (%), and the experimental items were measured for apparent density and thermal conductivity. As a result of the experiment, the apparent density and thermal conductivity tended to decrease as the mixing ratio of EPS beads increased. It is judged that the density decreased due to the low density and the micropores inside, and the thermal conductivity also decreased.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.3
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• pp.146-151
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• 2013

In this study, the effect of addition of waste glassy slag produced from recycling of spent catalyst (denoted as waste glass hereafter) on the physical properties of artificial aggregates made of coal bottom ash and dredged soil (7 : 3 by weight base) was evaluated. Especially, the bloating behavior of artificial aggregates was analyzed by performing the relation study between the apparent density, water absorption and microstructure. The apparent density of artificial aggregates increased slightly with sintering temperature at $1050{\sim}1150^{\circ}C$, but decreased above $1150^{\circ}C$ showing bloating phenomenon. The bloating behavior of artificial aggregates was decreased so the apparent density increased with amount of waste glass added. Also, the water absorption of artificial aggregates decreased with sintering temperature. Above $1200^{\circ}C$, big fissure and much liquid were formed at the surface of artificial aggregates and these phenomena could be suppressed by increasing amount of waste glass added. The artificial aggregates fabricated in this study had an apparent density of 1.1~1.6 and water absorption of 8~22 % which meet KS requirements for the artificial lightweight aggregates.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.654-658
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• 2012

In this work, the properties of an organic-inorganic hybrid insulating material using an inorganic filler and polyurethane foam with different foaming conditions were investigated. At weight ratios of polyol and isocyanate of 1 to 1.2 good foaming properties were noted. In addition, an addition of 0.4 g of water, 0.1 g of surfactant, and 0.1 g of catalyst with respect to the composites of polyol at 5 g and isocyanate at 6 g showed the lowest apparent density and thermal conductivity. The pore size was smaller in the organic-inorganic hybrid foaming body with an increase in the $CaCO_3$ addition amount. Moreover, the apparent density and thermal conductivity were increased when the added amount of $CaCO_3$ increased. Increasing the amount of $CaCO_3$ powder is expected to improve the flame retardant capabilities; however, doing this tends to increase the apparent density and thermal conductivity.

• Journal of the Korean Society of Tobacco Science
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• v.29 no.1
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• pp.23-29
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• 2007

The measurement of physical properties such as apparent density and void fraction of tobacco materials, which is so bulky, is a main theme with regard to tobacco process, quality control, cigarette combustion and smoke generation. Except Solution Impregnation Method, there was no alternative method for measuring those properties in the porous material so far. However, experimental processes of that method are so complicated as to cost much time and labor, the main solution such as mercury to apply to the method is usually very hazard. Therefore, we had developed a new method to determine them easily in our other paper by the mathematical equations derived from the Ergun equation for the purpose of it, and then already evaluated our method through applying some basic data from Muramatsu et at. (1979) with regard to our developed equations. Then, we found our method best fit to experimental one (Oh et al., 2001). In this study we tried to establish our method to conveniently determine those physical properties. Especially, we have focused on the development the easy way to measure surface area and the volume of single shred in a tobacco column. As a result of that, we found that the computer image analyzer was best fit for it. Then, we have finally determined apparent density and void fraction for our domestic tobacco shred.