• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.33.3-33
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• 2001

This paper considers a fault detection and diagnosis using estimation method in uncertain systems. In the state estimation method, we use the robust H$\infty$ FIR filtering algorithm. A novel aspect of the fault detection technique described here is that it explicitly accounts for the effects of simplified models and errors due to the linearization of nonlinear systems at an operating point.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.105
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• pp.129-133
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• 2006

In spite of the advantage of simple circuit, small size, and low price, predistortered power amplifier does not satisfy the IMD specification at low power range because of an IMD hump characteristic. To reduce the performance degradation by IMD hump, the method which is to control the operating point of amplifier according to its output power is presented. This method using envelope detection bias control is applied to the implemented class AB predistortered 16 W power amplifier. The measured result shows 10 dB improvement of $3^{rd}$ IMD performance in wide dynamic range of output power.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.9
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• pp.104-114
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• 1995

Mathematical models of industrial robots or manipulators are composed of highly nonlinear equations with nonlinear couplings between the variables of motions. These nonlin- earities were not considered important in the first stage that the working speed of the manipulator was not so fast, but the effect of nonlinear forces has become serious, as the working speed has been increased. So more improvement of performance cannot be expected by the control of manipulator using approximate linearization. As an approach for solving these problems, there is a method that eliminates nonlinear theory, which makes possible cecoupling of coupling terms and arbitrary arranging of poles is briefly introduced in this study. When the theory is applied to design the control law, its feasibility is examined whether the reasonable control results are obtained by simulating position, velocity, torque and tracing trajectory. The relations between the coefficients of the linearized differential equations and the maximum error and torque for the prescribed trajectory are also examined. Finally, the method for selecting the values for getting the most rapid and precise response within maximum torque of each drive is suggested in the choice of coefficients of characteristic equations which are obtained as a result of the control.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.3
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• pp.372-384
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• 1993

The inverted pendulum system has interesting and challenging problems related to robotics and rocket attitude control view of both control theory and applications. Generally approximately linearized plant models are employed to control the system. In this paper a recently developed control theory based on differentiable manifold theory is used to control the inverted pendulum system which is typically nonlinear. First, the nonlinear model is transformed into the approximate feedback linearized system by nonlinear state feedback. Secondly, the linear controller is designed using the pole-placement method for the approximate feedback linearized plant model, the output of which are finally inverse-transformed to yield the control input to the actual system of the inverted pendulum. The proposed method is evaluated by the computer simulation to compare with the 3rd order linearization model.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.11
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• pp.128-139
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• 1999

This paper proposes a linearization technique for the space vector modulation method, which increases the linear control range of inverter up to the 6-step inverter. This method is based on fourier series expansion of the desired output voltage of the inverter to calculate the compensation angle in continuous switching mode and holding angle in discontinuous switching including the 6-step mode respectively. The approximation equation of these angles are used for compensation of fundamental voltage in overmodulation range. Therefore, it is possible to obtain the linear control and the maximized utilization of PWM inverter output voltage.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.3
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• pp.179-192
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• 2008

A multiphase compensation method with mismatch linearization technique, is presented and demonstrated in a $\Sigma-\Delta$ fractional-N frequency synthesizer. An on-chip delay-locked loop (DLL) and a proposed delay line structure are constructed to provide multiphase compensation on $\Sigma-\Delta$ quantizetion noise. In the delay line structure, dynamic element matching (DEM) techniques are employed for mismatch linearization. The proposed $\Sigma-\Delta$ fractional-N frequency synthesizer is fabricated in a $0.18-{\mu}m$ CMOS technology with 2.14-GHz output frequency and 4-Hz resolution. The die size is 0.92 mm$\times$1.15 mm, and it consumes 27.2 mW. In-band phase noise of -82 dBc/Hz at 10 kHz offset and out-of-band phase noise of -103 dBc/Hz at 1 MHz offset are measured with a loop bandwidth of 200 kHz. The settling time is shorter than $25{\mu}s$.

• Journal of Biomedical Engineering Research
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• v.22 no.6
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• pp.479-486
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• 2001

Spirometer is a medical equipment which diagnoses respiratory function by measuring 9as volume across Patient's lunes through airway. Because a little overdose of anesthesia medicine can take away Patient's life in the ventilator for a surgical operation. an exact measurement of respiring volume is very important. This Paper Presented an exact flow volume calculation method from factors having an influence on measurement and introduced a spirometry system for an anesthesia ventilato. This system, using differential Pressure sensor measured flow by mutual relation with Pressure. temperature. gas density and linearization from the 2nd order characteristics of differential pressure with flow.

• Journal of Ocean Engineering and Technology
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• v.27 no.6
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• pp.56-64
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• 2013

Crabbing motion is the pure sway motion of a ship without surge velocity. Thus, it can be applied to a berthing operation. Crabbing motion is induced by a peculiar operation method called the push-pull mode. The push-pull mode is induced by using a combination of the main propeller and side thruster. Two propellers generating the same amounts of thrust and rotating in opposite directions produce some yawing moment on a vessel but do not induce longitudinal motion. With the additional operation of side thrusters, the push-pull mode is used to induce a large amount of lateral force. In this paper, three-degree-of-freedom equations of motion such as for the surge, sway, and yaw are constructed for the crabbing motion. Based on these equations of motion, a feedback linearization control method is applied to auto-berthing control for a twin-screw ship with side thrusters. The controller can deal with the nonlinearity of a system, which is present in the berthing maneuver of a twin screw ship. A simulation of the auto-berthing of a ship is performed to validate the performance of the designed controller.

• The Journal of the Acoustical Society of Korea
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• v.21 no.5
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• pp.478-484
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• 2002

Linear towed arrays (LTA) have a nonlinear shape due to tow vessel motion, ocean swells and currents. By reasons of nominally linear shape, various towed array shape estimation techniques have been developed since the perturbed shape cause the error in target detection. In this paper,, we propose the beamforming method for the perturbed LTA with simple structure. The proposed method linearizes a nonlinear phase of steering vector with position information measured by two reference sensors. It can be proved using some properties of Markov transition matrix, and iteration number of linearization process is decided by variance of cross phase difference. As a result of computer simulation in the ocean environment, beampattern of the proposed method is almost same with the ideal case in my type of array shape. In the signal-to-noise ratio (SNR) performance simlation, the DOA estimation performance of the proposed beamforming method is evaluated, and the comparison with Bartlett beamformer of the LTA shows that the proposed method can estimate. the spatial characteristic of sources more accuracy.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.6
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• pp.1-14
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• 2007

Optimal design method of nonlinear damping system for seismic response control of adjacent structures is studied in this paper. The objective functions of the optimal design are defined by structural response and total amount of the dampers. In order to obtain a solution minimizing two mutually conflicting objective functions simultaneously, multi-objective optimization technique based on genetic algorithm is adopted. In addition, stochastic linearization method is embedded into the multi-objective framework to efficiently estimate the seismic responses of the adjacent structures interconnected by nonlinear hysteretic dampers without performing nonlinear time-history analyses. As a numerical example to demonstrate the effectiveness of the proposed technique, 20-story and 10-story buildings are considered and MR dampers of which hysteretic behaviors vary with the magnitude of the input voltage are considered as nonlinear hysteretic damper interconnecting two adjacent buildings. The proposed approach can provide the optimal number and capacities of the MR dampers, which turned out to be more economical than the uniform distribution system while maintaining similar control performance. The proposed damper system is verified to show more stable performance in terms of the pounding probability between two adjacent buildings. The applicability of the proposed method to the design problem for optimally placing semi-active control system is examined as well.