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Three-dimensional computational fluid dynamics (CFD) modeling of the hydrodynamic characteristics for the various sand particle sizes (10 μm, 250 μm, 482 μm, 750 μm, 1000 μm, and the actual particle size distribution (PSD)) in a 0.1 MWthpilot-scale full-loop circulating fluidized bed combustor (CFBC) was numerically investigated with a commercial CFD code, ANSYS FLUENT. Those were clearly validated with actual CFBC operating data. As the result, the sand particle size of the actual PSD was in good agreement. In order to accurately simulate wood pellet combustion, kinetic parameters for activation energy (Ea) and pre-exponential factor (A) for wood pellet decomposition and char combustion were obtained from lab-scale TGA experiments with wood pellet sample actually used for CFBC operation. The CFD modeling on wood pellet combustion were conducted with the selected sand particle size of actual PSD with improved char combustion model using the user-defined function (UDF) reflected kinetic parameters. The CFD modeling results were carefully compared with actual CFBC operating results. Therefore, our CFD simulation results for the concentrations of gas species (N2, CO2, O2, SO2, CO, NO, and N2O) at the gas exit in the cyclone were also in good agreement with the actual CFBC operating data. The accuracy improvements were increased from 1.9 times to 2.5 times due to our improved char combustion model using the UDF.

We present a piezoresistive high-G accelerometer that achieves 1% cross-axis sensitivity, 200 kG shock endurance, and 90% fabrication yield. The special features and advances in the accelerometer are as follows. First, the cross-symmetric structure of the accelerometer is effective in reducing cross-axis sensitivity. Second, the piezoresistors implanted on the elastic beam surface at a low doping level result in a high gauge factor and sensitivity with excellent shock endurance. Third, the cross-symmetric structure, generating both tensile and compressive stresses on the elastic beam surface, forms a piezoresistor bridge interconnection on a single side of the accelerometer, thus simplifying the fabrication process as well as the wiring and packaging process with a high yield of 90%. Experimental characteristics of the fabricated accelerometer show a detection range of up to 200 kG, a resonant frequency of 577.04 ± 13.62 kHz, a prime-axis sensitivity of 1.01 $\pm 0.11 ~\mu \text{V}$ /G, a cross-axis sensitivity ratio of 0.98% ± 0.62%, and a linearity of 99.99% ± 0.08% over the detection range. The fabricated accelerometer shows only a 1.35% variation of prime-axis sensitivities at 20 kG before and after a shock of 200 kG, indicating its performance stability and repeatability. Therefore, the accelerometer demonstrates strong potential for high-G impact monitoring applications in the fields of defense, aerospace, marine, automotive, construction, and so on.

Carbon and semiconductor nanoparticles are promising photothermal materials for various solar-driven applications. Inevitable recombination of photoinduced charge carriers in a single constituent, however, hinders the realization of a greater photothermal effect. Core–shell heterostructures utilizing the donor–acceptor pair concept with high-quality interfaces can inhibit energy loss from the radiation relaxation of excited species, thereby enhancing the photothermal effect. Here, core–shell structures composed of a covellite (CuS) shell (acceptor) and spherical carbon nanoparticle (CP) core (donor) (abbreviated as CP/CuS) are proposed to augment the photothermal conversion efficiency via the Förster resonance energy transfer (FRET) mechanism. The close proximity and spectral overlap of the donor and acceptor trigger the FRET mechanism, where the electronic excitation relaxation energy of the CP reinforces the plasmonic resonance and near-infrared absorption in CuS, resulting in boosting the overall photothermal conversion efficiency. CP/CuS core–shell coated on polyurethane (PU) foam exhibits a total solar absorption of 97.1%, leading to an elevation in surface temperature of 61.6 °C in dry conditions under simulated solar illumination at a power density of 1 kW m–2(i.e., 1 sun). Leveraging the enhanced photothermal conversion emanated from the energy transfer effect in the core–shell structure, CP/CuS-coated PU foam achieves an evaporation rate of 1.62 kg m–2h–1and an energy efficiency of 93.8%. Thus, amplifying photothermal energy generation in core–shell structures via resonance energy transfer can be promising in solar energy-driven applications and thus merits further exploration.

To determine the effect of oral administration of porcine placental extract (PPE) on the menopausal symptoms of Korean women.

For polydimethylsiloxane (PDMS), a formation of interconnected pores and an addition of Silwet L-77 are, respectively, made as physical treatment and chemical one to change the material properties involved in the water permeable flow through PDMS. Here, we investigate a change in the water permeable flow through PDMS induced by physicochemical treatment. 28 kinds of physicochemically treated PDMS (pc-PDMS) blocks having different pore sizes of 50–500 µm and different Silwet L-77 concentrations of 0.0–8.0 wt% are prepared using a pressure-assisted compaction and NaCl particle-leaching technique. The values of mass flow rate and flow delay are obtained from pressure-driven water flow through pc-PDMS blocks as indexes for characterizing their water permeable flow. Our physicochemical treatment successfully controls the water permeable flow through PDMS, which means that pc-PDMS can be used for the development of powerless microfluidic regulators for aqueous chemicals in micro-total analysis systems (µ-TAS).

The GnF/SU-8 composites are new polymer matrix composites (PMCs) composed of graphite nanoflakes (GnFs) bound together by SU-8 photoresist. The PMCs therefore have excellent ultraviolet (UV) photopatternability and high electrical properties. In spite of the unique material properties of GnF/SU-8 composites, much still remains uncertain about their controllability in both UV photopatternability and electrical properties. Here, we investigate 7 kinds of GnF/SU-8 composites having different GnF concentrations of 5.0 to 25.0 wt.% to characterize the changes in the UV photopatternability (i.e., polymerized thickness and photopattern quality) and electrical conductivity of GnF/SU-8 composites caused by a variation in GnF concentration. The polymerized thickness of GnF/SU-8 composites is measured to be in the range of 4.06 to 23.99 μm, which is inversely proportional to GnF concentration and also directly proportional to UV dose (i.e., 345 to 3,450 mJ/cm2) because of the screening effect of GnF existed in the composites; the photopattern quality at the edge is in inverse proportion to GnF concentration. An increase in GnF concentration leads to a significant change in the electrical conductivity of GnF/SU-8 composites in a proportional way (up to 25.34 S/m). The GnF/SU-8 composites are expected to be widely used as UV photopatternable and electrically conductive PMCs for diverse engineering applications.

The graphite nanoflake (GnF)-reinforced polydimethylsiloxane (PDMS) composites (GnF/PDMS composites) are developed as new polymer matrix composites (PMCs) with controllable mechanoelectrical properties. Here, we investigate the effect of GnF concentration on the mechanoelectrical properties (i.e., elastic modulus, fracture strain, and conductivity) of GnF/PDMS composites; the change in the surface morphology of GnF/PDMS composites caused by a variation in GnF concentration is also explored. The mechanoelectrical properties are measured by performing tensile tests on the GnF/PDMS composite specimens with different GnF concentrations of 5.0, 10.0, 12.5, 15.0, 20.0, and 25.0 wt.%. The surface morphology is analyzed in terms of internal void formation and surface roughness. The elastic modulus is measured to be in the range of 1.62 to 13.8 MPa which is proportional to GnF concentration, while the fracture strain and electrical conductivity are respectively characterized to be in ranges of 0.09 to 2.09 and 0.3 to 221.0 S/m which are in inverse proportion to GnF concentration. An increase in GnF concentration leads to increases in internal voids’ amount and surface roughness. The GnF/PDMS composites can be used as sensing materials for detecting both small and large deformations in a variety of engineering applications.

We study the impact of gate stacks on the electrical characteristics of Zn-diffused source InxGa1?xAs tunneling field-effect transistors (TFETs) with Al2O3or HfO2/Al2O3gate insulators. Ta and W gate electrodes are compared in terms of the interface trap density (Dit) of InGaAs MOS interfaces. It is found that Ditis lower at the W/HfO2/Al2O3InGaAs MOS interface than at the Ta/HfO2/Al2O3interface. The In0.53Ga0.47As TFET with a W/HfO2(2.7 nm)/Al2O3(0.3 nm) gate stack of 1.4-nm-thick capacitance equivalent thickness (CET) has a steep minimum subthreshold swing (SS) of 57 mV/dec, which is attributed to the thin CET and low Dit. Also, the In0.53Ga0.47As (2.6 nm)/In0.67Ga0.33As (3.2 nm)/In0.53Ga0.47As (96.5 nm) quantum-well (QW) TFET supplemented with this 1.4-nm-thick CET gate stack exhibits a steeper minimum SS of 54 mV/dec and a higher on-current (Ion) than those of the In0.53Ga0.47As TFET.