Hyunchul Sohn

A modified skyhook control for the semi-active Macpherson suspension system is considered. A new quarter-car model, which incorporates the rotational motion of the unsprung mass, is introduced. A feedback control law in the form of a modified skyhook control is derived. Two filters to estimate the absolute velocity of the sprung mass and the relative velocity of the rattle space are designed. By including the actual semi-active damper in the loop of computer simulation, the nonlinearity, time-de

Abstract Chalcogenide materials of the amorphous phase with low band gaps were reported to show Ovonic threshold switching (OTS), making them suitable for selection devices in cross-point memory arrays. Herein, we report that ZnTe films with polycrystalline structures show OTS behavior. Nearly stoichiometric ZnTe thin films were deposited by an RF sputtering method. X-ray diffraction analysis indicated that the films were polycrystalline. The optical band gaps of the ZnTe films were estimated as

Multi-component chalcogenide thin films of GeTe x and GeTe x S 1− x are prepared by atomic layer deposition technique. With the conformal deposition characteristics, its electrical properties of threshold switching are demonstrated for emerging computing.

Ga2Te3 is of great interest because of its memory and threshold switching properties and potential for memory device application. Here, device of TiN/Ga2Te3/TiN with two terminals was fabricated and its threshold switching was investigated. Current–voltage measurements showed the ovonic threshold switching of amorphous Ga2Te3 thin films at 300 K with a high switching speed of about 10 ns. AC pulse tests showed reliable switching endurance over 109 switching cycles with the selectivity of 103. Am

Ovonic threshold switching (OTS) in chalcogenide materials has attracted considerable interest for application in electronic devices to suppress leakage current in cross-point array structures. Although OTS appears to originate from an electronic process, the exact mechanism of OTS remains unclear with respect to sub-threshold conduction and threshold switching. In this study, we demonstrated that the sub-threshold conduction characteristics is affected by the structures of the exponentially dis

In this research, 1-diode (1D), 1-resistor (1R), and 1D1R stacked devices were separately fabricated using a 400 nm diameter hole substrate. It was observed that, in 1D1R, there was a fivefold increase in endurance and 52% improvement in the resistance distribution characteristics compared to those of 1R. It could be surmised that the stacked diode not only plays the role of a selection device to minimize the interference in the crossbar array type resistive switching device but also acts as an

Negative differential resistance (NDR) in NbO x films attracts attention for potential application in neuromorphic computing. A continuous S‐type and abrupt snapback NDR characteristics are reported for NbO x devices. The NDR characteristics are expected to depend on the nature of the switching path in NbO x . Previous NDR studies have been performed mainly on amorphous NbO x films with an electroforming process to create a switching path. Herein, the NDR characteristics of a forming‐free NbO x

A comparative study of two electrode materials is conducted to demonstrate the effect of the electrode material on the resistive switching (RS) behavior of Ta 2 O 5 ‐based devices. Compared with a Pt top electrode (TE), application of a TiN TE shows an improved endurance of up to 10 9 cycles and a highly reliable 4 bit (16 states) operation. Various structural analyses reveal that this distinctive RS performance originates from an oxygen‐deficient layer (TaO x ) between the Ta 2 O 5 and TiN TEs.