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In this work, we propose ferroelectric-based reconfigurable field-effect transistors (FeRFETs) which can switch the polarity without program gate (PG). In FeRFETs, the non-volatile and reconfigurable electrostatic doping by ferroelectric enables the type conversion without PG. Through the TCAD simulations calibrated with the experimental data, we confirm a reconfigurable high doping level (> 1×1021 cm-3), a clear type conversion and highly tunable performance in FeRFETs. It is also found that carefully tailoring coercive field (EC) is important to maximize the performance of FeRFETs.

Purpose This paper aims to propose a method for manufacturing multi-material monolithic structures with flexible materials to construct the elastic body by using a dual-nozzle three-dimensional printer to develop a piezoelectric (PZT)-driven micropositioning stage with three degrees of freedom (3-DOF) and flexure hinges. Design/methodology/approach Polylactic acid (PLA) and nylon were used for the lever structure’s frame and flexure hinge, respectively. Additionally, the stage consisted of three PZT actuators for fine movement in the nanometer scale in 3-DOF (x, y and θ-directions). For the design of the stage, the kinematic analysis model and the finite element method (FEM) analysis was undertaken for comparing between PLA with nylon (multi-material), PLA (single material) and aluminum (conventional-material). In addition, two verification experiments were implemented for the fabricated prototype stage. First, to evaluate various assessments (lever ratio, hysteresis, coupling error and resolution), a measurement is carried out using the three capacitive sensors. Then, a two-camera-vision measurement experiment was performed to verify the displacement and lever ratio over the full-scale working range of the fabricated positioning stage, and the results from the experimentation and the FEM analysis were compared. Findings The authors confirmed enhancements in the properties of the lever structure frame, which requires stiffness and of the hinge, which requires flexibility for elastic deformation. Comparing FEM analysis and experimental results, although the performance as shown by experimental results was lower: the maximum difference being 3.4% within the end-point working range; this difference was sufficient to be a plausible alternative for the aluminum-based stage. Originality/value Multi-material monolithic-structure fabrication has an effective advantage in improving the performance of the stage, by using a combination of materials capable of reinforcing the desired characteristics in the necessary parts. It was verified that the fabricated stage can substitute the aluminum-based stage and can achieve a higher performance than single-material stages. Thus, precise-positioning stages can be manufactured in many kinds of structures with various properties and contribute to weight reduction and low costs for application equipment.

Fourier model–based multi-probe-error-separation is an error separation method that is useful for precise measurement of the rotation error motion of spindles or roundness profile of rotating machine parts. However, it is not yet widely used, because it suffers from the critical problem of harmonic distortion. This study explores the phenomenon of harmonic distortion in detail and analytically clarifies the principles behind its occurrence. The position at which harmonic distortion occurs can be calculated exactly and easily using principles related not only to probe arrangement angles, but also to measurement conditions such as data length and undulation range of interest. Based on these principles, we propose multi-probe system design guidelines for the effective selection of probe arrangement angles and avoidance of harmonic distortion. The reliability and usability of the proposed design method are verified by simulation tests; stable multi-probe-error-separation can easily be achieved using the proposed design technique. We conduct experimental tests using a special measuring system based on four probes composed of two different probe arrangement sets and verify that this multi-probe-error-separation method can acquire rotation error motion or roundness profile precisely without harmonic distortion.

In this study, a real-time measurement system to easily apply multi-probe error separation method for error motion measurement of a shaft was designed and developed. An arrangement condition of sensing probes for accurate multi-probe error separation method was examined and verified by a simulation test. By following the examined arrangement condition for multi-probe method, a measurement system to measure radial and tilt error motions of a shaft was designed and developed. The efficiency of the multi-probe method with the examined arrangement condition was checked by comparing the error motion results for a rotary stage with the error motions in the specifications of the guarantee. It is expected to apply this system to a real-time monitoring system of failure diagnosis for rotating shafts in ships and plants.

Tiled display systems are widely utilized for digital signage application exceeding the size of a single flat-panel display. Smoothly varying spatial non-uniformity in luminance and color may cause visible difference in the boundary of two adjacent sub-displays. It is necessary to suppress such visible artifacts. Tiled display systems can be installed under various illumination environments and require routine color calibration to compensate for temporal change in display characteristics. This paper presents a simple and cost-effective color calibration method for tiled display systems. Consumer-level digital camera is utilized as a measuring device after the proposed vignetting correction was applied. Experimental results indicate that the proposed color calibration method for tiled display system is quite effective in suppressing the visible artifacts across two adjacent sub-displays.

This work investigates the areal effect, a smoothing of the surface areal topography in measurements from optical instruments that arises from the use of discrete pixels. Two-dimensional and three-dimensional models for the process of acquiring areal topography data were developed and applied to three-dimensional reference surface textures of various traditional machined surfaces that were measured by an atomic force microscope. Sets of reference surface areal data were stitched by a three-dimensional stitching method prior to their use in simulations. Roughness parameters and cumulative power spectra of areal topography of the specimen surfaces measured by coherence scanning interferometry were calculated and compared to the results from the simulated profiles. The results from the simulated data profiles showed good agreement with profiles measured by a coherence scanning interferometry microscope. Finally, the relationship between the pixel size of the optical instruments and the resulting reliability of the high-frequency components of the acquired surface profiles was investigated with spectral analysis. Selection criteria for the magnification of the objective lens are proposed, which allow determination of the appropriate sensor spatial resolution for measurements based on the surface texture characteristics of the specimen.

In this paper, six-degree-of-freedom (DoF). Displacement measurement technique using a compact stereo-vision system is proposed. The measuring system consists of a camera, an optical prism, two plane mirrors, and a planar marker on a target. The target was attached on an object so that its six-DoF displacement can be calculated using a proposed coordinates estimating algorithm and stereo images of the marker. A prototype was designed and fabricated for performance test. From the test results, it can be confirmed that the proposed measuring technique can be applied to monitoring and control of various manipulators.

A 3D stitching algorithm was developed to measure wide-range data without reducing lateral resolution. This algorithm can correct X- and Y-axis rotational errors and Z-axis translational errors, as well as minimize the propagation of stitching error using an overall squared stitching method. Furthermore, the coordinate relation of adjacent areas is clearly defined to facilitate proper implementation of the algorithm. The developed algorithm has been applied with simulated and actual measured data to verify that it can stitch various types of data. The stitching accuracy on the common stitching area was evaluated using the Monte-Carlo method as the noise level increased to determine the criteria on measuring conditions. The stitching error was validated to be very small and to occur at the sub-nanometer level.

The amorphous InGaZnO (a-IGZO) is widely accepted as a promising channel material for thin-film transistor (TFT) applications owing to their outstanding electrical properties [1, 2]. However, a-IGZO TFTs have still suffer from their bias instability with illumination [1-4]. Up to now, many researchers have studied the sub-gap density of states (DOS) as the root cause of instability. It is well known that defect states can influence on the performances and stabilities of a-IGZO TFTs. The defects states should be closely related with the deposition condition, including sputtering power, and pressure. Nevertheless, it has not been reported how these defects are created during conventional RF magnetron sputtering. In general, during conventional RF magnetron sputtering process, negative oxygen ions (NOIs) can be generated by electron attachment in oxygen atom near target surface and then accelerated up to few hundreds eV by a self-bias; at this time, the high energy bombardment of NOIs induce defects in oxide thin films. Recently, we have reported that the properties of IGZO thin films are strongly related with effects of NOIs which are generated during the sputtering process [5]. From our previous results, the electrical characteristics and the chemical bonding states of a-IGZO thin films were depended with the bombardment energy of NOIs. And also, we suggest that the deep sub-gap states in a-IGZO as well as thin film properties would be influenced by the bombardment of high energetic NOIs during the sputtering process. In this study, we have studied the gate bias instability and their density of states (DOSs) of a-IGZO TFTs as depending on the bombardment of NOIs during conventional magnetron sputtering. Finally, we will introduce our novel technology named as Magnetic Field Shielded Sputtering (MFSS) process to prevent the NOIs bombardment effects and present how much to be improved the instability of a-IGZO TFTs by this new deposition method. 1. M.G. Kim, M.G. Kanatzidis, A. Facchetti, and T.J. Marks, Nat. Mater. 10, 382 (2011). 2. K.K. Banger, Y. Yamashita, K. Mori, R.L. Peterson, T. Leedham, J. Rickard, and H. Sirringhaus, Nat. Mater. 10, 45 (2011). 3. M.D.H. Chowdhury, P. Migliorato, and J. Jang, Appl. Phys. Lett. 98, 153511 (2011). 4. X. Xiao, W. Deng, S. Chi, Y. Shao, X. He, L. Wang, and S. Zhang, IEEE Trans. Electron Devices 60, 4159 (2013). 5. D.H. Kim, J.N. Jang, S.B. Yoon, and MunPyo Hong, Appl. Phys. Express 7, 031401 (2014).