Synthesis of mesoporous tungsten oxide nanofibers using the electrospinning method

Mesoporous tungsten oxide nanofibers were synthesized via a 500 °C thermal treatment of composite nanofibers prepared by electrospinning an ethanol solution consisting of tungsten ethoxide, P123 triblock copolymer, and polyvinylpyrrolidone. The as-electrospun composites exhibited unwoven nanofibers with an average diameter of 233 nm and a smooth surface morphology. During the calcination process, the composite nanofibers were shrunk to 85 nm in diameter and converted into rough, wormhole-like nanofibers. These were formed by agglomerating polycrystalline WO₃ particles of 10–30 nm along the axial direction. Furthermore, a measured pore-size distribution indicated that this nanofiber mat had different types of meso-sized porosities, which may have resulted from their wormhole-like structures and inter-fiber voids. In addition, it was observed to have the intra-grain porosity with the diameter of about 1.0 nm.     

Functional properties of different Korean sweet potato varieties

Eight different varieties of Korean sweet potatoes (SPs) were investigated to develop new healthy foods. The purple-fleshed SPs, ‘Shinjami’ and ‘Borami’, the orange-fleshed SPs, ‘Juwhangmi’ and ‘Shinwhangmi’, and the white/cream-fleshed dry-type SPs, ‘Shinyulmi’, ‘Shinchunmi’, ‘Yeonwhangmi’, and ‘Jeungmi’, were used. Alcohol insoluble solids (AIS), total dietary fiber (TDF), anthocyanin, carotenoid, and phenolic compounds contents for SP powders vary significantly (p<0.05) between different varieties. The TDF, anthocyanin, and the total phenolic compounds of SPs had the highest values in the purple-fleshed SPs (10.11–10.87%, 2.43–3.35 mg/g, and 454.13–638.79%, respectively) and the lowest values in the white/cream-fleshed dry-type SPs. The carotenoids of the orange-fleshed SPs were higher in ‘Juwhangmi’ than in ‘Shinwhangmi’. The color differences among the purple-fleshed SPs were 3–4 times larger than those of other SPs. The antioxidant activities of the purple-fleshed SPs were higher than those of other SPs.     

Deep-sea water supplementation and swimming exercise improves bone metabolism in growing rats fed a high-fat diet

This study was examined the effects of deepsea water (DSW) supplementation and swimming exercise on bone metabolism in growing male rats. Thirty-two Sprague-Dawley male rats, 6 weeks of age, were randomly divided into high-fat diet sedentary (HS, n=8) or exercised group (HE, n=8) and DSW supplemented sedentary (DS, n=8) or exercised group (DE, n=8), given a high fat diet to all groups for 8 weeks. In the results, serum osteocalcin level of the DS was significantly lower than that of the HS (p<0.01). In addition, femoral bone mineral density (BMD), tibial bone mineral content (BMC), and breaking force of the DS were significantly higher than that of the HS (p<0.05). Furthermore, femoral BMD and tibial weight of DE were significantly higher than that of the HE (p<0.05). These results suggest that drinking deep-sea water and exercise has a crucial role for prevent osteoporosis and increase peak bone mass in growing male rats.     

A conservative method of wavelet neural network based meta-modeling in constrained approximate optimization

The paper aims at the development of the wavelet neural network (WNN) based conservative meta-model that satisfies the constraint feasibility of approximate optimal solution. The WNN based constraint-feasible meta-model is formulated via exterior penalty method to optimally determine interconnection weights and dilation and translation coefficients in the network. Using Ackley’s path function, the approximation performance of WNN is first tested in comparison with BPN. The proposed approach of constraint feasibility is then verified through a ten-bar planar truss problem. For constrained approximate optimization, the structural design of a composite rotor blade is explored to support the proposed strategies.     

Effects of Annealing Temperature on Microstructure and Tensile Properties in Ferritic Lightweight Steels

An investigation was conducted into the effects of annealing temperature on microstructure and tensile properties of ferritic lightweight steels. Two steels were fabricated by varying the C content, and were annealed at 573 K to 1173 K (300 °C to 900 °C) for 1 hour. According to the microstructural analysis results, κ-carbides were formed at about 973 K (700 °C), which was confirmed by equilibrium phase diagrams calculated from a THERMO-CALC program. In the steel containing low carbon content, needle-shaped κ-carbides were homogeneously dispersed in the ferrite matrix, whereas bulky band-shaped martensites were distributed in the steel containing high carbon content. In the 973 K (700 °C)-annealed specimen of the steel containing high carbon content, deformation bands were formed throughout the specimen, while fine carbides were sufficiently deformed inside the deformation bands, thereby resulting in the greatest level of strength and ductility. These results indicated that the appropriate annealing treatment of steel containing high carbon content was useful for the improvement of both strength and ductility over steel containing low carbon content.     

A study on tension behavior considering thermal effects in roll-to-roll E-printing

The mathematical model for tension in a moving web by Shin [1] was extended by considering thermal strain due to temperature fluctuations in the drying of a roll-to-roll system. The extended model describes variations in tension and includes terms that represent the change of the Young’s Modulus, the thermal coefficient, and the thermal strain. In this paper, a new control scheme based on the extended model is proposed for mitigation of tension disturbances due to thermal strain in the drying process. Tension feedback control logic generally is not be applied due to the fact that register errors can be induced by speed alterations that help to compensate for tension disturbances. But in our approach, the thermal strain in the web is compensated for by means of velocity adjustments without adding extra register errors in the steady state. A computer simulation followed by an experimental validation was carried out to confirm the performance of the proposed method. The results show that the proposed model is useful for describing tension behavior and suggest that tension control logic improves control precision for the drying module of a roll-to-roll e-printing system.     

Enforcement avoidance behavior near automated speed enforcement areas in Korean expressways

Automated speed enforcement system (ASES) has been deployed as a safety countermeasure on Korean roadways to reduce speeding-related traffic crashes; information on ASES locations is mandated to be open to the public. However, because drivers are alerted about enforcement via on-board navigation systems and roadside signs, they can avoid enforcement by momentarily reducing their speeds near ASES locations. This enforcement avoidance behavior (EAB) can induce sudden changes in speed near the enforcement locations and thereby increase risk of crash occurrence.