• 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 International Society for Simulation Surgery
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• v.4 no.1
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• pp.1-8
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• 2017

In the field of tissue engineering, researches have been actively conducted to regulate stem cell fate by understanding the interaction between cell and materials. This approach is expected as a promising therapeutic method in the future medicine by utilizing differentiation of stem cells into desired cells or tissues using biomaterial. For this regenerative medicine, there exist lots of attempts to construct optimized structures of various shapes and sizes that can regulate the stem cell fate. In this review, we will empathize the topographic effect as stem cell niche on the mesenchymal stem cell (MSC) response (cell attachment, proliferation, and differentiation) according to the shape and size of the structure of the substrates, and comprehensively analyze the importance and the effect of shape and size of the surface topography.

• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.366-370
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• 1995

The ballistic efficiency of alumina tiles with various sizes, shapes, and target configurations was measured by the thick backing plate technique. The ballistic efficiency of square tiles roughly 8 mm thick struck by 12.7mm diameter bullets rapidly increased with tile size up to about 100mm, then tended to saturate. Circular shape tiles had lower ballistic efficiencies than those of square shape tiles for the same width and thickness. Small tiles (50mm) that were recessed in aluminum wells had a significantly higher ballistic efficiency than tiles placed on a flat surface. However, the difference in the ballistic efficiency between the two target configurtions became small at larger tile sizes. All the results could be explained by the effect of reflected waves at edges and the propagation of resulting cracks on the penetration process.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.375-382
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• 2004

The compressive strength of concrete is used as the most basic and important material Property when reinforced concrete structures are designed. It has become a problem to use this value, however, because the control specimen sizes and shapes are different from every country. In this study, the effect of specimen sizes and shapes on compressive strength of concrete specimens was experimentally investigated based on fracture mechanics. Experiments for the Mode I failure was carried out by using cylinder, cube, and prism specimens. The test results are curve fitted using least square method(LSM) to obtain the new parameters for the modified size effect law(MSEL). The analysis results show that the effect of specimen sizes and shapes on ultimate strength is apparent. In addition, correlations between compressive strengths with size, shape, and casting direction of the specimen are investigated. For cubes and prisms the effect of placing direction on the compressive strength was investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1453-1463
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• 2013

In this study, we investigated the effect of the indenter geometry on the crack characteristics by indentation cracking test and FEA. We conducted various cohesive finite element simulations based on the findings of Lee et al. (2012), who examined the effect of cohesive model parameters on crack size and formulated conditions for crack initiation and propagation. First, we verified the FE model through comparisons with experimental results that were obtained from Berkovich and Vickers indentations. We observed whether nonsymmetrical cracks formed beneath the surface during Berkovich indentation via FEA. Finally, we examined the relation between the crack size and the number of cracks. Based on this relation and the effect of the indenter angle on the crack size, we can predict from the crack size obtained with an indenter of one shape (such as Berkovich or Vickers) the crack size for an indenter of different shape.

• Journal of the Korean Ceramic Society
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• v.22 no.6
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• pp.21-28
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• 1985

The properties of magnetic recording materials largely depend on their shape magnetic anisotropy. The control of their shape and size distribution is very important for improving magnetic properties. The silica-coated goethite$(SiO_2$/$\alpha$-FeOOH=1.5wt%) having acicular shape was prepared. The sillica-coated goethite was heat-treated at 40$0^{\circ}C$~1,00$0^{\circ}C$ 1hr and then reduced at 50$0^{\circ}C$ 2hr. When the silica-coated goethite was heat-treated at 80$0^{\circ}C$ its acicular shape was maintained and its magnetic properties were improved(Hc: 1,325 Oe $\sigma$m:138.8 emu/g, Rs:0.56) However the acicular shape of the paricles was broken for non-coated hematite obtained by dehydration at 80$0^{\circ}C$ They were sintered and showed poor magnetic properties.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.8
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• pp.790-796
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• 2008

Typical solid rocket motors have a fixed propellant grain shape and nozzle throat size resulting in a fixed motor thrust. Pintle nozzle has been suggested as a means of providing variable thrust while maintaining the inherent advantage of solid rocket motors. In this study, the pintle shape effect on nozzle performance is investigated using experimental-aided Computational Fluid Dynamics(CFD). The pintle shape is modified by a principle of monotony. CFD analysis is performed using Fluent by applying the turbulent model. This analysis indicates that nozzle thrust and pintle load are influenced by change of nozzle shock pattern and flow separation due to pintle shape and there exists a high-performing pintle shape.

• Korean Journal of Human Ecology
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• v.1 no.2
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• pp.113-118
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• 1998

Clothing shape is principally described in seven factors that are composed of clothing design, clothing material, clothing size, pattern design, sewing method and body motion etc.. The aims of this study was to measurement out-line space-shape variation of clothing fitness with somato type by using the image processing. The subjects for direct anthropometric measurements were 248 female college students aged from 19 to 22. The data were statistically analyzed by principal analysis and cluster analysis. The results were obtained three somato type. Also I made skirts in order to analyzed to the out-line space-shape variation of clothing fitness with body. The effect of somato type on the shape of flare skirts was determined by the out-line space-shape variation of clothing fitness with body. The out-line space-shape variation of clothing fitness with body was observed between the node number and amplitudes of clothing wave form and node number was determined at the maxim of space-shape amplitude, and the space-shape amplitudes have related with aspect ratio of cross-sectional shape. Results for flare skirts show changes in amplitude and mean with fabrics, somato type. therefore gray-level histogram are correlated with changes out-line space-shape, differences in drape spacing and related fabric properties and their somato type. (Korean J Human Ecology 1(2):113∼110 1998)

• Journal of Powder Materials
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• v.17 no.2
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• pp.130-135
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• 2010

Sm-16.7wt%Co alloy powders were prepared by high energy ball milling under the conditions of various milling time and the content of process control agent (PCA), and their microstructure and magnetic properties were investigated to establish optimum processing conditions. The initial powders employed showed irregular shape and had a size ranging from 5 to $110\;{\mu}m$. After milling for 5 h, the shape of powders changed to round shape and their mean powder size was approximately $5\;{\mu}m$, which consisted of the agglomerated nano-sized particles with 15 nm in diameter. The coercivity was reduced with increasing the milling time, whereas the saturation magnetization increased. As the content of PCA increased, the powder size minutely decreased to approximately $7\;{\mu}m$ at the PCA content of 10 wt%. The XRD patterns showed that the main diffraction peaks disappeared apparently after milling, indicating the formation of amorphous structure. The measured values of coercivity were almost unchanged with increasing the content of PCA.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.9
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• pp.28-34
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• 2022

The flow at the top surface of the hopper is of particular industrial interest. Previously, the velocity distribution inside the hopper was predicted using the simple, void and spot models, which are equations for the particle flow field. However, because these equations cannot predict the velocity distribution at the top surface, a new equation has been recently proposed. This study employed the discrete element method with the changed shape of the particles. Based on the results, the shape of the particle had no effect on the discharge angle and shape of the velocity distribution; however, it greatly affected the size of the velocity distribution and bed thickness of the flowing particles. Therefore, in the future, it is necessary to modify the theoretical equation by considering the shape of the particles.