• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.10
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• pp.51-63
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• 1995

In this paper, a new real-time optical image switching system based on the phase-typed BPEJTC is suggested. The phase filter mask which has the arbitrary position mapping function between input and output planes is constructed by using the modified JTPS of the BPEJTC. Then, the input image is convolved with this phase filter mask in the spatial frequency domain and through further Fourier transform the input image is switched to the new positions in the output correlation plane where the correlation peaks are occurred. And, based on the computer simulation results, the practical optical switched to the new positions in the output correlation plane where the correlation peaks are occurred. And, based on the computer simulation results, the practical optical switching system is opto-digitally constructed and through some experiments on image switching the possiblity of real-time implementation of the multiple optical image switching system by using the BPEJTC is suggeste.

• Journal of Magnetics
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• v.14 no.3
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• pp.104-107
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• 2009

The effects of the magnetic property variation on current-induced magnetization switching in magnetic tunnel junction with perpendicular magnetic anistoropy (PMA) and the soft magnetic polarization-enhancement layers (PELs) inserted between the layers with PMA and the MgO layer was studied. A micromatnetic model was used to estimate the switching time of the free layer by different applied current densities, with changing saturation magnetization ($M_s$) of the PELs, interlayer exchange coupling between PMA layers and PELs. The switching time could be significantly reduced at low current densities, by increasing $M_s$ of PELs and decreasing interlayer exchange coupling.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.3
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• pp.228-236
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• 1989

The theroy of variable structure control system (VSS) is applied to the position control for DC servo-motors. In order to use the microcomputer as a control device, the principles of VSS for the continuous-time system are extended to the discrete-time system. A new switching law is proposed to achieve the reduction of chattering. It adds a new switching structure to the conventional switching sturctures. This switching region is set near and including the conventional switching curve. The new algorithm is obtained for single-input second order system, and applied to the position control of a DC servo-motor. Experimental results show that the transient behavior is improved due to the reduction of chattering and good robustness properties are demonstrated.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.5
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• pp.57-64
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• 2015

This paper proposes a new switching algorithm for an controllable clamp snubber to improve the efficiency of a fly-back converter system. This system uses an controllable clamp method for the snubber circuit for the efficiency and reliability of the system. However, the active clamp snubber circuit has the disadvantage that system efficiency is decreased by switch operating time because of heat loss in resonance between the snubber capacitor and leakage inductance. To address this, this paper proposes a new switching algorithm. The proposed algorithm is a technique to reduce power consumption by reducing the resonance of the snubber switch operation time. Also, the snubber switch is operated at zero voltage switching by turning on the snubber switch before main switch turn-off. Experimental results are presented to show the validity of the proposed controllable clamp control algorithm.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.33-37
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• 2004

To meet an increasing demand for high performance in gun dynamic plant, both a precise and a fast response positioning are strongly required for the gun servomechanism control. A mode switching control(MSC) system, which includes a fine stabilizing controller, fast positioning one and a switching function, is widely used to meet this requirement. Stabilization is performed through PID controller, while proximate time optimal servo(PTOS) is used for target designation. Because gun dynamic have large damping comparing to acceleration, PTOS algorithm with damping is newly derived. This paper adopts the initial value compensation method that improve the transient response after switching. Some simulation results are given to show the effectiveness of our scheme.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.1
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• pp.1-8
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• 2005

We fabricate PLT(5) thin film on Pt/TiO/sub x/SiO₂/Si substrate by using sol-gel method and investigate leakage current, switching and retention properties. The leakage current density of PLT(5) thin film is 3.56×10/sup -7/A/㎠ at 4V. In the examination of switching properties, pulse voltage and load resistance were 2V～5V and 50Ω～3.3kΩ, respectively. Switching time has a tendency to decrease from 0.52㎲ to 0.14㎲ with the increase of pulse voltage, and also the time increases from 0.14㎲ to 13.7㎲ with the increase of load resistance. The activation energy obtained from the relation of applied pulse voltage and switching time is about 135kV/cm. The error of switched charge density between hysteresis loop and experiment of polarization switching is about 10%. Also, polarization in retention decreases as much as about 8% after l0/sup 5/s.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.285-285
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• 2016

Resistive random access memory devices have been widely studied due to their high performance characteristics, such as high scalability, fast switching, and low power consumption. However, fluctuation in operational parameters remains a critical weakness that leads to device failures. Although the random formation and rupture of conducting filaments (CFs) in an oxide matrix during resistive switching processes have been proposed as the origin of such fluctuations, direct observations of the formation and rupture of CFs at the device scale during resistive switching processes have been limited by the lack of real-time large-area imaging methods. Here, a novel imaging method is proposed for monitoring CF formation and rupture across the whole area of a memory cell during resistive switching. A hybrid structure consisting of a resistive random access memory and a light-emitting diode enables real-time monitoring of CF configuration during various resistive switching processes including forming, semi-forming, stable/unstable set/reset switching, and repetitive set switching over 50 cycles.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.7
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• pp.50-57
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• 2000

We propose a logic synthesis algorithm for the design of FPGAs operating at high speed. FPGA is a novel technology that provides programmability in the field. Because of short turnaround time and low manufacturing cost, FPGA has been noticed as an ideal device for system prototyping. Despite these merits, FPGA has drawbacks, namely low integration and long delay time comparing to ASIC. The proposed algorithm partitions a given circuit into subcircuits utilizing a kernel divisor such that the subcircuits can be performed at the same time, hence reducing the delay of the circuit. Experimental results on the MCNC benchmark show that the proposed algorithm is effective by generating circuits having 19.1% les delay on average, when compared to the FlowMap algorithm.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.6
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• pp.71-78
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• 2002

A method of soft switching in the half bridge converter using a small saturable core is presented. For the soft switching, a small dead time of both switch off is made in a pair of MOSFET switch. The saturable core is of rectangular magnetization characteristics and the core flux swings from the minus to the plus saturation during ON time of the switch. The soft switching is realized in dead time by a resonance between the saturating inductance of the core and the stray capacitance of MOSFET. As an extension of this concept, instead of the saturable core, we propose a new soft switching circuit using a linear inductance and two switches, which is especially suitable for regulating the output and also for high frequency switching. A theoretical principle of soft switching presented here was confirmed by experiments on a half bridge converter of 1.25 KW.

• Journal of Power Electronics
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• v.12 no.5
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• pp.769-777
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• 2012

In this paper, a new development in the time optimal control theory in sliding mode control systems for multi-quadrant buck converters with a variable load is presented. In general, the closed-loop time optimal control system is applied to multi-quadrant buck converters for output regulation, so that an optimal switching surface is obtained. Moreover, an adjusted optimal sliding mode controller is suggested which adjusts the controller parameters to give an optimal switching surface. In addition, a description of the transient response of the closed-loop system is proposed and used to damp any output or input disturbances in minimum time. Numerical simulations and experimental results are employed to demonstrate that the output regulation time and transient performances of dc/dc converters using the proposed technique are improved effectively when compared to the classical sliding mode control method.