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The purpose of this study was to compare the gender differences in isokinetic hamstring to quadriceps (H/Q) and hip abductor to adductor (AB/AD) strength ratios at different angular velocities in collegiate taekwondo athletes. Thirty collegiate taekwondo athletes (15 females and 15 males) participated in this study. Maximal isokinetic hamstring and quadriceps strengths were measured at different angular velocity (60° s−1, 120° s−1, and 240° s−1) with isokinetic dynamometer (Cybex 770, USA). They also performed five isokinetic hip abductor and adductor contractions at 30° s−1, and 60° s−1 on a following day. Female athletes showed significantly lower in H/Q peak torque ratios than male athletes at 60° s−1 (right and left, p

During five-axis machining of impeller, the excessive local interference avoidance leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to improve the efficiency of five-axis machining of impellers, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. By using an MC-space algorithm for interference avoidance, an MB-spline algorithm for continuous control was intended to create a five-axis machining tool path with excellent surface quality and economic feasibility. A five-axis cutting experiment was performed to verify the effectiveness of the continuity control. The result shows that the surface shape with continuous method is greatly improved, and the surface roughness is generally favorable. Consequently, the effectiveness of the suggested method is verified by identifying the improvement of efficiency of five-axis machining of an impeller in aspects of surface quality and machining time.

We investigated the sintering and consolidation phenomena of silver nanoparticles under various thermal treatment conditions when they were patterned by a contact printing technique on polyimide substrate films. The sintering of metastable silver nanoparticles commenced at 180 °C, where the point necks were formed at the contact points of the nanoparticles to reduce the overall surface area and the overall surface energy. As the temperature was increased up to 250 °C, silver atoms diffused from the grain boundaries at the intersections and continued to deposit on the interior surface of the pores, thereby filling up the remaining space. When the consolidation temperature exceeded 270 °C, the capillary force between the spherical silver particles and polyimide flat surface induced the permanent deformation of the polyimide films, leaving crater-shaped indentation marks. The bonding force between the patterned silver metal and polyimide substrate was greatly increased by the heat treatment temperature and the mechanical interlocking by the metal particle indentation.

The microstructural characterization of inkjet-printed Ag films sintered at various conditions was carried out to analyze the effect of microstructure on mechanical and electrical properties. As expected, the films became denser with grain growth with increasing sintering time and temperature, which resulted in improvement in mechanical properties. However, the resistivity of the films reached a minimum value of 3.0 μΩ cm before full densification. In order to improve the mechanical properties, pressure-assisted sintering was introduced. As a result, inkjet-printed Ag films sintered at 250°C under 5 MPa showed a tensile strength of 550 MPa, elongation of 2.4%, Young’s modulus of 55 GPa, and resistivity of ~3.0 μΩ cm.

Inkjet printing is considered one of the most promising methods for patterning and materials deposition. The feasibility of employing inkjet technology for the creation of conductive pathways on printed circuit boards is addressed herein. Prediction of the width, length, and thickness of printed lines as a function of the dot diameter, resolution, and volume fraction of the particles in the ink is presented. Surface treatment of the substrate to promote desirable adhesion and wetting properties as well as the adjustment of the curing process to reduce the surface roughness of the printed traces were studied. In a sintering study, samples sintered at 250°C for 20 min showed a resistivity of 4.2 μΩ cm, which is approximately 2.6 times that of bulk silver. A low-temperature sintering method through the reduction of a metal salt is presented. The resistivity of printed samples sintered at 140°C for 30 min in the presence of silver nitrate with N,N-dimethylformamide showed a resistivity of 22.5 μΩ cm.

The ultra-drawing process of an ultra high molecular weight polyethylene (UHMWPE) gel film was examined by incorporating linear low-density polyethylene (LLDPE) and BaTiO3 nanoparticles. The effects of LLDPE and the draw ratios on the morphological development and mechanical properties of the nanocomposite membrane systems were investigated. By incorporating BaTiO3 nanoparticles in the UHMWPE/LLDPE blend systems, the ultra-drawing process provided a highly extended, fibril structure of UHMWPE chains to form highly porous, composite membranes with well-dispersed nanoparticles. The ultra-drawing process of UHMWPE/LLDPE dry-gel films desirably dispersed the highly loaded BaTiO3 nanoparticles in the porous membrane, which could be used to form multi-layered structures for electronic applications in various embedded, printed circuit board (PCB) systems.

This paper describes the speckle shearing interferometry, a non-destructive optical method, for quantitative estimation of void defect and monitoring separation defect inside of a pneumatic tire. Previous shearing interferometry has not supplied quantitative result of inside defect, due to effective factors. In the study, factors related to the details of an inside defect are classified and optimized with pipeline simulator. The size and the shape of defect can be estimated accurately to find a critical point and also is closely related with shearing direction. The technique is applied for quantitative estimation of defects inside of a pneumatic tire. The actual traveling tire is monitored to reveal the cause of separation and the starting points. And also unknown void defects on tread are inspected and the size and shape of defects are estimated which has good agreement with the result of visual inspection.

This study discusses a non-contact optical technique (electronic speckle pattern interferometry) that is well suited for thermal deformation measurement without any surface preparation and compensating process. Fiber reinforced plastics ([0]16, [0/90]8S) were analyzed by ESPI to determine their thermal expansion coefficients. The thermal expansion coefficient of the transverse direction of a uniaxial composite is evaluated as 48.78×10−6(1/°C). Also, the thermal expansion coefficient of the cross-ply laminate [0/90]8S is numerically estimated as 3.23×10−6 (1/°C) that is compared with that measured by ESPI.

In the world, there are several types of vibration, and these vibrations especially affect the mechanical industry. In this paper, experimental analysis of vibration modes of plates is discussed. Electronic speckle pattern interferometry (ESPI) is one of the optical nondestructive testing techniques. By using the ESPI, vibration modes of plates with various excitation points, ratio of longitudinal and lateral length, and materials are measured and qualitatively compared with the results of theoretical analysis proposed by Warburton. Finally, these vibration modes are quantitatively compared with the result of FEM analysis. The results of this study are as follows: (1) By comparing the theoretical and experimental frequencies, we confirmed qualitatively that deviations of frequencies are within 10% in accuracy. (2) By comparing the experimental vibration mode shapes with the numerical ones of the FEM analysis, we can conclude quantitatively that measuring vibration modes by using the ESPI has high accuracy.

Two-dimensional in-plane displacements and strains are measured using an electronic speckle pattern interferometry (ESPI) system based on the dual beam speckle interferometric method. Different types of specimens are used: a flat plate, a cracked-plate, and plate with a central hole of 12 mm diameter. Two-dimensional fringes obtained from real-time images are analyzed by an image analyser. The values of in-plane strains obtained by the ESPI technique show high accuracy compared with those measured by strain gages.