• Journal of Korean Association for Spatial Structures
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• v.22 no.1
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• pp.51-57
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• 2022

In this paper, based on the finite element analysis model verified in previous studies, a new model of a buckling restrained brace reinforced with a steel plate was proposed. A design formula was proposed for the new model to dissipate energy without buckling the steel core under load protocol, and the performance of the model satisfying the design formula was evaluated by comparing it with the previous model through the results of hysteresis loop, bi-linear curve, cumulative energy dissipation capacity, and equivalent viscous damping.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.316-322
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• 2002

This paper presents the temperature-dependent hysteresis identification of an electro-rheological (ER) fluid under various operating temperatures using the Preisach model. As a first step, polymethylaniline (PMA) particles are prepared and mixed with silicone oil to make an ER fluid. A couette type electroviscometer is then employed to obtain the field-dependent shear stress. In order to show the suitability of the Preisach model to predict a physical hysteresis phenomenon of the ER fluid, two significant properties; the minor loop property and the wiping-out property are experimentally examined under three dominant temperature conditions. Subsequently, the Preisach model fur the PMA-based ER fluid is identified using experimental first order descending (FOD) curves. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one under the both specified and unspecified temperatures. In addition, the hysteresis model proposed in this work is compared to Bingham model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.8
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• pp.648-656
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• 2002

This paper presents the identification of temperature-dependent hysteresis of an electro-rheological (ER) fluid under various operating temperatures using the Preisach model. As a first step, polymethylaniline (PMA) particles are prepared and mixed with silicone oil to make an ER fluid. A couette type electroviscometer is then employed to obtain the field-dependent shear stress. In order to show the suitability of the Preisach model to predict a physical hysteresis phenomenon of the ER fluid, two significant properties; the minor loop property and the wiping-out property are experimentally examined under three dominant temperature conditions. Subsequently, the Preisach model for the PMA-based ER fluid is identified using experimental multiple first order descending (FOD) curves. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one under the both specified and unspecified temperatures. In addition, the hysteresis model proposed in this work is compared to Bingham model.

• Journal of the Korean Ceramic Society
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• v.38 no.7
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• pp.667-671
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• 2001

Sawyer-tower 회로를 이용한 강유전 이력곡선의 측정과정에서의 주요 오차 원인을 살펴보고 이에 대한 대안을 제시해 보았다. 강유전체 시편에 존재하는 직류 누설성분에 의해 잔류분극과 항전계는 과대평가될 수 있는 위험성이 항상 있음을 알 수 있었으며 이러한 오차의 보정에 대하여 논의하였다. 또한 강유전 이력곡선의 측정에서 측정하는 시간이 증가되면서 시편의 발열로 인해서 시편의 온도가 증가하게 되어 잔류분극 값과 항전계 값이 감소하는 경향으로 나타남을 관찰하였고, 그 대책을 제안하였다.

• Proceedings of the Korean Magnestics Society Conference
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• 2014.05a
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• pp.85-85
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• 2014

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.10a
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• pp.137-137
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• 1997

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.05a
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• pp.52-52
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• 1997

• Transactions on Electrical and Electronic Materials
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• v.11 no.6
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• pp.275-278
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• 2010

We have examined the Ferroelectric properties of $PbZr_{0.4}Ti_{0.6}O_3$ (PZT) grains by monitoring the surface potential through the utilization of Kelvin force microscopy. Hysteretic and time dependent behaviors of small and large grains were compared with each other. The smaller grain yields had smaller values of surface potential. However, the normalized voltage versus surface potential behavior indicates that the smaller grains became saturated earlier with respect to the writing voltages than did the larger grains. On the other hand, the surface potential hysteresis loop obtained from the smaller grains showed a similar shape to what might be obtained from a Zr rich PZT film. In contrast the hysteresis loop of the larger grain looks like that obtained from a Ti-rich film. In addition, the time dependent behaviors of the smaller grains also revealed a better response than the response of larger grains. The overall ferroelectric properties of the smaller grains seem better than corresponding properties for larger grains. The Ti/Zr ratio of the PZT film which was examined in this study was 60/40.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.2
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• pp.193-200
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• 2014

Piezoelectric actuators have been widely used in various applications because they have many advantages such as fast response time, repeatable nanometer motion, and high resolution. However Piezoelectric actuators have the strong hysteresis effect. The hysteresis effect can degrade the performance of the system using piezoelectric actuators. In past study, the parameters of the inverse hysteresis model are computed from the identified parameters using the Generalized Prandtl-Ishlinskii(GPI) model to cancel the hysteresis effect, however according to the identified parameters there exist the cases that can't form the inverse hysteresis loop. Thus in this paper the inverse hysteresis modeling mothod is proposed using the Inverse Generalized Prandtl-Ishlinskii(IGPI) model to handle that problem. The modeling results are verified by experimental results using various input signals.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.582-586
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• 2005

This paper presents a new structure of Phase Locked Loop(PLL) which changes its loop bandwidth according to the locking status. The proposed PLL consists of a conventional PLL and, Locking Status Indicator(LSI). The LSI decides the operating bandwidth of loop filler. When the PLL becomes out of lock, the PLL increases the loop bandwidth and achieves fast locking. When the PLL becomes in-lock, this PLL decreases the loop bandwidth and minimizes phase noise output. The PLL can achieve fast locking and low phase noise output at the same time. Proposed PLL's locking time is less than $40{\mu}s$ and spur is 76.1dBc. It is simulated by HSPICE in a Hynix CMOS $0.35{\mu}m$ Process.