• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.9
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• pp.511-519
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• 2003

In this paper, we considered the design of gain scheduled controllers for linear systems with saturating actuators. Our basic idea is to design a control that uses higher control gain when the states are smaller, and lower gain when it is higher. By doing this, we can avoid the saturation and we can improve the performance. First, we derive a control and a reachable set expressed as LMI form, which minimizes not only the L$_2$ gain from the disturbance to the measured output but also the control is never saturated within this reachable set. Next, the reachable set is divided as nested subsets, and at each nested subset, the control gain is designed to minimize the L$_2$ gain and it is never saturated. Finally, the control gain is scheduled according to the status of states, i.e., the subset in which the states are located. A numerical example is presented to show that our gain scheduled control significantly improves the performance.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.335-338
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• 2003

In this paper, we considered the design of gain scheduled controllers for linear systems with input constraints. The gain scheduled control is a method that uses larger control gain when the states are smaller, and smaller gain when it is larger. By doing this, we can use a full actuator capacity. Also we allow the over-saturation in control to improve the performance. First, we derive a control and a reachable set expressed as LMI form, while minimizing the $L_2$ gain from the disturbance to the measured output. Next, the reachable set is divided as nested subsets, and the control gains are obtained by minimizing the $L_2$ gain at each nested subset. Finally, the control gains are scheduled according to the status of states, i.e., the nested-subset in which the states are located. Performance of the proposed technique is illustrated through simulations of a six-story building subject to earthquake ground motion.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.915-920
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• 2007

A new optimal state feedback and disturbance feedforward control design in the sense of minimizing $L_{2}-gain$ from disturbance to control output is proposed for disturbance attenuation of systems with bounded control input and measurable disturbance. The controller is derived in the framework of linear matrix inequality(LMI) optimization. A gain scheduled state feedback and disturbance feedforward control design is also suggested to improve disturbance attenuation performance. The control gains are scheduled according to the proximity to the origin of the state of the plant and the magnitude of disturbance. This procedure yields a stable linear time varying control structure that allows higher gain and hence higher performance controller as the state and the disturbance move closer to the origin. The main results give sufficient conditions for the satisfaction of a parameter-dependent performance measure, without violating the bounded control input condition.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.11
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• pp.59-65
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• 2007

A new optimal state feedback and disturbance feedforward control design in the sense of minimizing $L_2$-gain from disturbance to control output is proposed for disturbance attenuation of systems with bounded control input and measurable disturbance. The controller is derived in the framework of linear matrix inequality(LMI) optimization. A gain scheduled state feedback and disturbance feedforward control design is also suggested to improve disturbance attenuation performance. The control gains are scheduled according to the proximity to the origin of the state of the plant and the magnitude of disturbance. This procedure yields a stable linear time varying control structure that allows higher gain and hence higher performance controller as the state and the disturbance move closer to the origin. The main results give sufficient conditions for the satisfaction of a parameter-dependent performance measure, without violating the bounded control input condition.

• Journal of Korean Biological Nursing Science
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• v.21 no.3
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• pp.169-177
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• 2019

Purpose: The purpose of this paper was to identify blood pressure, interdialytic weight gain, thirst and intradialytic discomfort in subjects after applying individual low-sodium dialysis fluid (1,2,3 mEq/L) to hemodialysis patients for 12 weeks. Methods: This study was a non-equivalent pre-post design. For 12 weeks, dialysate concentration was maintained at 1 mEq/L or 2 mEq/L or 3 mEq/L based on average sodium concentration of each individual, and the difference was compared after applying individually. Results: Change in blood pressure significantly decreased in the group where in pre-hemodialysis systolic pressure decreased the gradient of sodium concentration in serum sodium and dialysis solution by 2mEq/L. Interdialytic weight gain, and thirst showed significant decrease in all three groups. But in all three groups, intradialytic discomfort among dialysis showed no significant changes. Conclusion: Although application of low sodium dialysis fluid showed no change in intradialytic discomfort, lowered blood pressure, thirst, and interdialytic weight gain, which could be used for individual showing increased interdialytic weight gain and increased blood pressure. There is need for continued study on this.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.12-16
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• 2003

This paper presents a compensation method for a temperature-dependent gain tilt in L-band erbium-doped fiber amplifier using a voltage-controlled attenuator. The gain tilts in the L-band of 1570-1605 nm due to a temperature change have negative slopes, whereas they have positive slopes for the increasing optical input powers in a saturation region. The proposed method utilizes these opposite gain variations to compensate for the gain tilt over a wide range of temperature. While applying forty channels with a channel spacing of 100 GHz in the L-band and changing the ambient temperature from 0 to $50^{\circ}C$, the compensation method maintained the gain deviation within 1 dB.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.9
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• pp.743-749
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• 2002

A 1.5V 70㏈ 100MHz CMOS class-AB complementary operational amplifier is presented. For obtaining the high gain and the high unity gain frequency, the input stage of the amplifier is designed with rail-to-rail complementary differential pairs which are symmetrically parallel-connected with the NMOS and the PMOS differential input pairs, and the output stage is designed to the rail-to-rail class-AB output stage including the elementary shunt stage technique. With this design technique for output stage, the load dependence of the overall open loop gain is improved and the push-pull class-AB current control can be implemented in a simple way. The designed operational amplifier operates perfectly on the complementary mode with 180$^{\circ}$ phase conversion for 1.5V supply voltage, and shows the push-pull class-AB operation. In addition, the amplifier shows the DC open loop gain of 70.4 ㏈ and the unity gain frequency of 102 MHz for $C_{L=10㎊∥}$ $R_{L=1㏁}$ Parallel loads. When the resistive load $R_{L}$ is varied from 1 ㏁ to 1 ㏀, the DC open loop gain of the amplifier decreases by only 2.2 ㏈.a$, the DC open loop gain of the amplifier decreases by only 2.2 dB.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.727-732
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• 2020

In this paper, when a refractive index grating and a gain grating were simultaneously present in a DFB laser having a wavelength of 1.55 ㎛, a dielectric film coating was applied so that reflection did not occur on the right mirror surface, so that 𝜌_r=0. In case of δL > 0, the threshold gain and the beam distribution in the longitudinal direction and the radiated power ratio P_l/P_r of the oscillation mode were compared for the cases of the phase of 𝜌_l=π and π/2. If the phase of 𝜌_l=π, in order to obtain a low threshold current and high frequency stability, κL should be greater than 8. In the case of the phase of 𝜌_l= π/2, when κL is larger than 4.0, the oscillation gain starts to be lower than when the phase of 𝜌_l=π. In order to lower the threshold current of a oscillation mode and enhance the frequency stability, κL should be greater than 8.

• Journal of Software Assessment and Valuation
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• v.16 no.2
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• pp.117-125
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• 2020

In this paper, when both the refractive index grating and the gain grating exist in a 1.55um DFB laser with two cleaved mirror facets, when the phase of ρ_l is fixed to 0 and the phase of ρ_r is changed to -π/2, π, π/2, 0, the change in frequency and oscillation gain was theoretically analyzed. In the case of δL<0, the oscillation gain required for lasing is the lowest and the most stable frequency operation is obtained in the case of (ρ_l phase=0, ρ_r phase=0) and κL=10, when κL is varied from 0.1 to 10. In the case of δL>0, when (ρ_l phase=0, ρ_r phase=π) and κL=10, the oscillation gain required for lasing is the lowest and the difference between the oscillation gains of the higher-order modes is large so that the most stable frequency operation is obtained.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.2
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• pp.195-203
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• 2016

In order to overcome the influence of system stability and accuracy caused by uncertainty, estimation errors and external disturbances in Eight-Rotor MAV, L2 gain control method was proposed based on interval type II fuzzy neural network identification here. In this control strategy, interval type II fuzzy neural network is used to estimate the uncertainty and non-linearity factor of the dynamic system, the adaptive variable structure controller is applied to compensate the estimation errors of interval type II fuzzy neural network, and at last, L2 gain control method is employed to suppress the effect produced by external disturbance on system, which is expected to possess robustness for the uncertainty and non-linearity. Finally, the validity of the L2 gain control method based on interval type II fuzzy neural network identifier applied to the Eight-Rotor MAV attitude system has been verified by three prototy experiments.