Homogeneous mixtures of hydroxyapatite (HAp) and yttria-stabilized zirconia (YSZ)
nanoparticles were successfully synthesized using chemical co-precipitation and subsequent
calcination. For the synthesis of HAp/YSZ nanopowder, the Ca/P atomic ratio was
1.73 to obtain high-content stoichiometric hydroxyapatite phase and to suppress
β-tricalcium
phosphate (β-TCP) formation. The agglomerated crystalline powders were milled using YSZ ball media
to obtain well-separated nanoparticles. The final particle size of the HAp and YSZ was
∼50–70
and ∼15–30 nm, respectively. The crystallinity and morphological feature of the nanopowder was
analysed using x-ray diffraction (XRD) and high-resolution transmission electron
microscopy (HRTEM) analyses. The ball-milled nanopowder mixture was hot pressed at
1100 °C
for 1 h under 20 MPa in vacuum atmosphere. The sintered HAp/YSZ nanocomposites exhibited
approximately 99% of the theoretical density, due not only to the fine nanoscale of the
particles, but also to the homogeneous distribution of the nanoparticle mixture. They also
showed fine grain structures of the HAp phase due to the suppressed grain growth by YSZ
particles. The nanocomposites showed improved mechanical properties, flexural strength of
∼155 MPa and fracture
toughness of ∼2.1 MP m1/2, due to the YSZ contribution to the HAp matrix.
High-rise building construction demands precise planning prior to actual operation. High-rise building construction has widely been planned in urban area. Curtain wall operation is one of important and fundamental operations in high-rise building construction. Curtain wall operation is composed of various activities. Precise planning is required for the effective management of such operation. Construction simulation technique has been considered an appropriate methodology for estimating construction performance which is required for the effective management of the project. However, simulation technique revealed serious limitations. Simulation technique has difficulty in preliminary modeling and application of changed conditions. This paper suggests a preliminary study for the research that overcomes traditional simulation technique limitations focusing on curtain wall operations.
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