• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.10
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• pp.917-925
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• 2016

Schmitt Trigger logic is a gate level design method to have hysteresis characteristics to improve noise immunity in digital circuits. Dynamic Threshold voltage MOS(DTMOS) Schmitt trigger circuits can improve noise immunity without adding additional transistors but by controlling substrate bias. The performance of DTMOS Schmitt trigger logic has not been verified yet in standard CMOS process through measurement. In this paper, DTMOS Schmitt trigger logic was implemented and verified using Magna $0.18{\mu}m$ MPW process. DTMOS Schmitt trigger buffer, inverter, NAND, NOR and simple digital logic circuits were made for our verification. Hysteresis characteristics, power consumption, and delay were measured and compared with common CMOS logic gates. EM Immunity enhancement was verified through Direct Power Injection(DPI) noise immunity test method. DTMOS Schmitt trigger logics fabricated using CMOS process showed a significantly improved EM Immunity in 10 M~1 GHz frequency range.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.5
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• pp.694-699
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• 2012

This paper proposes a new sensorless speed control scheme of permanent magnet DC motor using a numerical model and hysteresis controller, which requires neither shaft encoder, speed estimator nor PI controllers. By supplying the identical instantaneous voltage to both model and motor in the direction of reducing torque difference, the rotor speed approaches to the model speed, namely setting value and the system can control motor speed precisely. As the numerical model whose electric parameters are the same as those of the actual motor is adopted, the armature rotating speed can be converged to the setting value by controlling torque on both sides to be equalized. And the hysteresis controller controls torque by restricting the torque errors within respective hysteresis bands, and motor torque are controlled by the armature voltage. The experiment results indicate good speed and load responses from the low speed range to the high, show accurate speed changing performance.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.173-178
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• 2010

Electric railroad systems consist of supply system of electric power and electric locomotive. The electric locomotive is adapted to high speed driving and mass transportation due to obtaining high traction force. The electric locomotive is operated by motor blocks and traction motors. Train speed is controlled by suppling power from motor blocks to traction motors according to reference speed. Speed control of the electric locomotive is efficient by spending minimum energy between motor blocks and traction motors. Recently, induction motors have been used than DC and synchronized motors as traction motors. Speed control of induction motors are used by vector control techniques. In this paper, speed of the induction motor is controlled by using the vector control technique. Control system model is presented by using Simulink. Pulse is controlled by PI and hysteresis controller. IGBT inverter is used for real-time control and system performance is demonstrated by simulating the induction motor which has 210[kW] on the output power.

• Journal of Biosystems Engineering
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• v.31 no.4 s.117
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• pp.315-322
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• 2006

A torsional damper comprised of two stage pre-dampers was used to reduce the rattle noise generated in the PTO gear box of a direct engine-PTO driveline of agricultural tractors. It was designed and mounted to the engine flywheel to reduce the torque fluctuation-induced speed variations at the driving gears in the PTO gearbox, which were found to be main cause of the rattle noise. The effects of a hysteresis torque and a torsional stiffness of the damper on the speed variation were analyzed using an 11 degree of freedom non-linear model of the damped PTO driveline. The torsional damper was represented by a single degree of freedom model with 7 parameters. Under a constant hysteresis torque, velocity variation was reduced with decrease in the torsional stiffness of the damper. The velocity variation was also decreased with decrease in the hysteresis torque under a constant torsional stiffness. Optimum values of the torsional stiffness and hysteresis torque were obtained by the model simulation for the PTO driveline under the study. When the optimum values of the damper were used, the sound pressure level of the rattle noise was reduced by 81%, resulting in a reduction of 15dB(A). The optimum damper also reduced the engine speed variation, resulting in a reduction of 80% at the driving gears in the PTO gearbox. The torsional damper showed a good performance in reducing the rattle noise caused by the speed variation in the direct engine-PTO driveline.

• Smart Structures and Systems
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• v.16 no.1
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• pp.163-181
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• 2015

This research investigates the structural health monitoring of nonlinear structures after a major seismic event. It considers the identification of flag-shaped or pinched hysteresis behavior in response to structures as a more general case of a normal hysteresis curve without pinching. The method is based on the overall least squares methods and the log likelihood ratio test. In particular, the structural response is divided into different loading and unloading sub-half cycles. The overall least squares analysis is first implemented to obtain the minimum residual mean square estimates of structural parameters for each sub-half cycle with the number of segments assumed. The log likelihood ratio test is used to assess the likelihood of these nonlinear segments being true representations in the presence of noise and model error. The resulting regression coefficients for identified segmented regression models are finally used to obtain stiffness, yielding deformation and energy dissipation parameters. The performance of the method is illustrated using a single degree of freedom system and a suite of 20 earthquake records. RMS noise of 5%, 10%, 15% and 20% is added to the response data to assess the robustness of the identification routine. The proposed method is computationally efficient and accurate in identifying the damage parameters within 10% average of the known values even with 20% added noise. The method requires no user input and could thus be automated and performed in real-time for each sub-half cycle, with results available effectively immediately after an event as well as during an event, if required.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.311-316
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• 1991

This paper deals with designing the PID autotuner. The system parameters are identified using the relay control, where the unidirectional relay with hysteresis is adopted. The digital PID tuning rule on Nyquist plot is derived, and the statistical wordlength is adopted for the coefficient wordlength. The experimental results of temperature control exhibit the satisfactory performance and the validity of the derived statistical wordlength.

• Elastomers and Composites
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• v.56 no.4
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• pp.209-216
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• 2021

In this study, we observed the mechanical properties, thermal stability, and low temperature sealing performance of fluorosilicone elastic composites. When the blend ratio of Phenyl vinyl methyl silicone (PVMQ) was increased, the tensile strength, modulus at 100%, and compression set were decreased. The thermal stability of fluorosilicone elastic composites showed a similar tendency. These were caused by poorer green strength of PVMQ than Fluorosilicone rubber (FVMQ). The change in the tensile strength and elongation at -40℃ showed a decreasing tendency with increasing PVMQ blend ratio. By increasing the PVMQ blend ratio, low-temperature performance was improved. The Dynamic mechanical analysis (DMA) results showed that T_g was decreased and low-temperature performance was improved with increasing PVMQ blend ratio. However tanδ was decreased becaused of the poor green strength and elasticity of PVMQ. From a hysteresis loss at -40℃, the hysteresis loss value was increased and fluorosilicone elastic composites showed the decreasing tendency of elasticity with increasing PVMQ blend ratio. From the TR test, TR10 was decreased with increasing PVMQ blend ratio. FS-4 (45% PVMQ blended composites) showed a TR10 of -68.0℃ that was 5℃ lower than that of FS-1 (100% FVMQ). The gas leakage temperature was decreased with increasing PVMQ blend ratio. The gas leakage temperature of FS-4 was -69.2℃ that was 5℃ lower than that of FS-1. Caused by the polymer chain started to transfer from a glassy state to a rubbery state and had a mobility of chain under T_g, the gas leakage temperature showed a lower value than T_g. The sealing performance at low temperature was dominated by T_g that directly affected the mobility of the polymer chain.

• Journal of Magnetics
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• v.15 no.2
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• pp.85-90
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• 2010

This paper deals with the efficiency evaluations in a synchronous reluctance motor (SynRM) versus a permanent magnet assisted SynRM (PMASynRM), using a coupled transient finite element method (FEM) and Preisach modeling, which is presented to analyze the characteristics under the effects of saturation and hysteresis loss. We herein focus on the efficiency evaluation relative to hysteresis loss and copper loss on the basis of load conditions in a SynRM and PMASynRM. Computer simulation and experimental results for the efficiency, using a dynamometer, show the propriety of the proposed method and the high performance of the PMASynRM.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1105-1110
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• 2011

This paper presents an improved direct torque control based on artificial neural networks technique. The major problem that is usually associated with DTC drive is the high torque(speed) ripple. To overcome this problem a torque hysteresis band with variable amplitude is proposed based on artificial neural networks. The artificial neural networks proposed controller is shown to be able to reducing the torque(speed) ripple and dependency on motor parameter and to improve performance DTC especially at high speed and reversal running.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.873-876
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• 2005

The nonlinear characteristics of a damper is directly related to the car behavior and performance, both for handling and comfort. So considering the nonlinear characteristics of a damper such as hysteresis is important to analyze the dynamic characteristics of a car suspension. In this study, a mathematical nonlinear dynamic damper model based on experimental data is devised to estimate the nonlinear parameters of a NEW EF-SONATA damper using the least square method. The devised nonlinear dynamic damper model is used to analyze the reaction force of a NEW EF-SONATA suspension using ADAMS. The simulation results are good agreement with the experimental data than those of the linear model.