• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.12
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• pp.1-7
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• 2008

Magnetic Tunneling Junction (MTJ) has been used as a nonvolatile universal storage element mainly in memory technology. However, according to several recent studies, magneto-logic using MTJ elements show much potential in substitution for the transistor-based logic device. Magneto-logic based on MTJ can maintain the data during the power-off mode, since an MTJ element can store the result data in itself. Moreover, just by changing input signals, the full logic functions can be realized. Because of its programmability, it can embody the reconfigurable magneto-logic circuit in the rigid physical architecture. In this paper, we propose a novel 3-bit arbitrary magneto-logic circuit beyond the simple combinational logic or the short sequential one. We design the 3-bit magneto-logic which has the most complexity using MTJ elements and verify its functionality. The simulation results are presented with the HSPICE macro-model of MTJ that we have developed in our previous work. This novel magneto-logic based on MTJ can realize the most complex logic function. What is more, 3-bit arbitrary logic operations can be implemented by changing gate signals of the current drivel circuit.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.1
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• pp.1-7
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• 2007

An MTJ element not only computes Boolean function but also stores the output result in itself. We can make the most use of magneto-logic's merits by employing the magneto-logic in substitution for the sequential logic as well as the combinational logic. This unique feature opens a new horizon for potential application of MTJ as a universal logic element. Magneto-logic circuits using MTJ elements are more integrative and non-volatile. This paper presents novel 3-bit magneto-logic up/down counters and presents simulation results based on the HSPICE macro-model of MTJ that we have developed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.9
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• pp.10-17
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• 2007

It opens a new horizon on spintronics for the potential application of MTJ as a universal logic element, to employ the magneto-logic in substitution for the transistor-based logic device. The magneto-logic based on the MTJ element shows many potential advantages, such as high density, and nonvolatility. Moreover, the MTJ element has programmability and can therefore realize the full logic functions just by changing the input signals. This magneto-logic using MTJ elements can embody the reconfigurable circuit to overcome the rigid architecture. The established magneto-logic element has been designed and fabricated on a triple-layer MTJ. We present a novel magneto-logic structure that consists of a single layer MTJ and a current driver, which requires less processing steps with enhanced functional flexibility and uniformity. A 4-bit gray counter is designed to verify the magneto-logic functionality of the proposed single-layer MTJ and the simulation results are presented with the HSPICE macro-model of MTJ that we have developed.

• Smart Structures and Systems
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• v.12 no.6
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• pp.595-617
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• 2013

Semi-active control equipments are used to effectually enhance the seismic behavior of structures. Magneto-rheological (MR) dampers are semi-active devices that can be utilized to control the response of structures during seismic loads and have received voracious attention for response suppression. They supply the adaptability of active devices and stability and reliability of passive devices. This paper presents an optimal fuzzy logic control scheme for vibration mitigation of buildings using magneto-rheological dampers subjected to near-fault ground motions. Near-fault features including a directivity pulse in the fault-normal direction and a fling step in the fault-parallel direction are considered in the requisite ground motion records. The membership functions and fuzzy rules of fuzzy controller were optimized by genetic algorithm (GA). Numerical study is performed to analyze the influences of near-fault ground motions on a building that is equipped with MR dampers. Considering the uncontrolled system response as the base line, the proposed method is scrutinized by analogy with that of a conventional maximum dissipation energy (MED) controller to accentuate the effectiveness of the fuzzy logic algorithm. Results reveal that the fuzzy logic controllers can efficiently improve the structural responses and MR dampers are quite promising for reducing seismic responses during near-fault earthquakes.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.7
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• pp.572-577
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• 2005

This paper applies the fuzzy logic controller to a semiactive seat suspension system in order to obtain the better ride comfort in constraint of specific rattle space. The seat suspension system used for this research is a scissors-type one with the MR (Magneto Rheological) fluid damper. Since a seat suspension system with a driver can not be exactly modeled, it is effective to control with the fuzzy logic controller. The rule was carefully tuned to effectively reduce the vibration transmitted to a driver. The on-road ride was realized on a hydraulic excitor and the result shows that the fuzzy controller has reduced the vibration of a seat suspension system compared to the continuous skyhook controller.

• Ocean Systems Engineering
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• v.8 no.2
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• pp.201-221
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• 2018

In this paper a comprehensive study for the structural control of Jacket platform with Magneto-Rheological (MR) damper is presented. The control is implemented as a closed loop feedback of the applied voltage in the MR Damper using fuzzy logic. Nine cases of combinations with MR damper are presented to complete the work. The selection of the MR damper (RD 1005-3) is based on the operating parameters (i.e., the range of frequency and displacement). Bingham model is used to obtain the control forces. The damping co-efficient of the model is obtained using empirical relationship between the voltage in the MR damper and input velocity from the structural members. The force acting on the structure is obtained from Morison equation using P-M spectrum. The results show that the reliable control was obtained when there was a continuous connection of multiple MR dampers with the lower levels of the structure. Independent MR dampers at different levels provided control within a range, while the MR dampers placed at alternate positions gave very high control.

• Structural Engineering and Mechanics
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• v.36 no.2
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• pp.181-195
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• 2010

Coupled building control is a viable method to protect tall buildings from seismic excitation. In this study, the semi-active control of a building complex is investigated for mitigating seismic responses. The building complex is formed of one main building and one podium structure connected through Magneto-Rheological (MR) Dampers and Tuned Mass Damper. The conventional semi-active control techniques require a primary controller as a reference to determine the desired control force, and modulate the input voltage of the MR damper by comparing the desired control force. The fuzzy logic directly determines the input voltage of an MR damper from the response of the MR damper. The control performance of the proposed fuzzy control technique for the MR damper is evaluated for the control problem of a seismically-excited building complex. In this paper, a building complex that include a 14-story main building and an 8-story podium structure is applied as a numerical example to demonstrate the effectiveness of semi-active control with Magneto-Rheological dampers and its comparison with the passive control with the Tuned Mass Damper and two uncoupled buildings and hybrid semi-active control including the Tuned Mass Damper and Magneto-Rheological dampers while they are subject to the earthquake excitation. The numerical results show that semi-active control and hybrid semi-active control can significantly mitigate the seismic responses of both buildings, such as displacement and shear force responses, and fuzzy control technique can effectively mitigate the seismic response of the building complex.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.69-79
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• 2011

This paper proposes a GA-based optimal fuzzy control technique for the vibration control of earthquakeexcited adjacent structures interconnected with semi-active magneto-rheological(MR) dampers. Rule-based fuzzy logic controllers are designed first by implementing heuristic knowledge and the genetic algorithm(GA) is then introduced to optimally tune the fuzzy controllers for enhancing the seismic performance of semi-active control system. For practical implementation, the fuzzy controller simply uses locally measured responses of the dampers involved and directly returns the input voltage to the magneto-rheological dampers in real time through the fuzzy inference mechanism. The local measurement based fuzzy controller provides optimal damping force in a decentralized manner so that it does not require a primary central controller unlike the conventional semi-active control techniques. As a result, it can avoid the unbridgeable discrepancy between the desired control force and the actual damper force that may occur in the conventional control approaches. The validity and effectiveness of the proposed control method are shown numerically on two 20-story earthquake-excited buildings interconnected with MR dampers.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.1
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• pp.27-32
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• 2002

This paper describes a fuzzy steering controller for an outdoor autonomous mobile robot using MR(magneto-resistive) sensor. Using the magnetic field difference values(dBy, dBz) obtained from the MR sensor, we designed fuzzy logic controller for driving the robot on the road center and proposed a method to eliminate the Earth magnetic field. To develop an autonomous mobile robot simulation program, we have done modeling MR sensor, mobile robot and coordinate transformation. A computer simulation of the robot including mobile robot dynamics and steering was used to verify the driving performance of the mobile robot controller using the fuzzy logic. So, we confirmed the robustness of the proposed fuzzy controller by computer simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1986-1991
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• 2007

In this paper, we discussed, intelligent soft filter for MR(magnetoresistive) sensor. Most navigation systems today use some type of compass to determine heading direction. Using the earth's magnetic field, electronic compass based on MR(magnetoresistive) sensors can electrically resolve better then 0.1 degree rotation. Intelligent methode for soft building a one degree compass using MR(magnetoresistive) sensors will also be discussed. Compensation techniques are shown to correct for compass tilt angels and nearby ferrous material disturbances. we proved the fuzzy logic that based on the way the ham deals with inexact information is useful for MR sensors.