• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.584-586
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• 2005

The stroke of piston in the linear compressor driven by LPMSM can be obtained from integrating the input voltage and current of LPMSM, and may be diverged due to dc components In the voltage and current. The strategy to prevent the divergence of stroke using both the high-pass filter and dc offset compensation was suggested. The equations for the magnitude and phase of the stroke and also dc offset including the stroke are derived as a function of the cut-off frequency of HPF. The performance of stroke calculation scheme has been verified by experimentally on a linear compressor drive system, where the control was implemented by a 16-bit DSP.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2763-2765
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• 2000

The interactions between the excavation tool and the excavation environment are dynamic, unstructured and complex. In addition. operating modes of an excavator depend on working conditions, which makes it difficult to derive the exact mathematical model of excavator. Even after the exact mathematical model is established, it is difficult to design of a controller because the system equations are highly nonlinear and the state variable are coupled. The objective of this study is to design a fuzzy logic controller (FLC) which controls the position of excavator's attachment. This approach enables the transfer of human heuristics and expert knowledge to the controller. Expeiments are carried out to check the performance of the FLC.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.864-866
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• 2000

In the slotted motor, cogging torque is generated due to the interaction between the rotor magnets and the slots on the stator. It is well known that cogging torque produces vibration and noise which may be detrimental to the performance of position and speed control system. Hence, the prediction of cogging torque is very important at the design stage of BLDC motor. In this paper, permanent magnets with different arc an91e of inner and outer radius is proposed. The cogging torque of proposed model and conventional one is analyzed by 2-D FEM and compared.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.127-133
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• 2001

The flexibility of long reach manipulators presents a difficult control problem when accurate end-point position is required. Input shaping by convolving system commands with impulse sequences has been shown to be an effective method of reducing residual vibrations in flexible systems. However, existing shapers has been considered robustness for only frequency uncertainty. However, this paper presents new multi-hump convolution(CV) input shaper that could accommodate with the simultaneous variation of natural frequency and damping ratio. Comparisons with previously proposed input shapers are presented to illustrate the qualities of the new input shaper. These new shapers will be shown to have better robustness for the variation of frequency and damping ratio.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.13-13
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• 2002

A Spatial light modulator (SLM) is a real-time programmable device having the modulation function of the amplitude, phase or polarization of an optical wavefront as a function of position via electrical or optical control signals. Various types of reusable SLMs with two-dimensional pixel arrays are centrally important devices in volumetric recording, data processing, pattern recognition, optical computer and other optical system. (omitted)

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.484-489
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• 1998

In this paper, we examine the displacement characteristics of the parallel leaf spring mechanism with large-deflective elastic hinges, and the validity of this mechanism as a translational and rotational mechanism is confirmed with multi-input system. This study is focused on the linear driving force as an input force, which is applied to the large-deflective elastic mechanism, and the displacement characteristics are discussed with theoretically and experimentally. The motions of this mechanism due to large-deflective hinges are changed by the position of loading force regardless of a single driving force. The numbers of degree of freedom are increased with the hinges, and we can be used to a multiple driving force in order to obtain many types of Output.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.601-604
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• 2004

Precise position and attitude control of pico-satellite requires huge number of impulses of the order of 10$^{-6}$ Ns. MEMS solid rocket array is a promising propulsion system but the higher degree of miniaturization causes unreliable operation mainly due to quenching. In order to breakthrough this situation, a novel design of solid micro-rocket is proposed, which generates tiny impulses repetitively from a single rocket not from array. This unique micro-rocket is based on the utilization of quenching, which causes propellant reaction to sustain only in a small area. A test chip of a micro solid propellant tank and micro heater array is fabricated and ignition test is conducted. Obtained results show the feasibility of this concept and future direction of this quenching-based propulsion is discussed.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.873-876
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• 1993

A fuzzy controller designed by mini-max-gravity(MMG) method is essentially nonlinear with respect to the controller's input and output relationship, and stability analysis is thus needed to construct a stable control system. This paper deals with a design method of a position-type MMG fuzzy controller stable in a sense of Lyapunov when considered is a single-input-single-output linear, stable plant. We first introduce a method to construct a Laypunov function by using an eigen-value of A matrix of the linear, stable plant dynamics and then we derive an asymtotic stability condition in terms of scale factors for fuzzy state variables and controller gain. The stability condition is found reasonably practical through comparing the theoretical stability region with that obtained from simulations.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.1
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• pp.1-8
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• 2003

Generally, thrust force of double-sided LPM is more powerful than that of single-sided LPM. Also, double-sided LMP can be effectively applied to the high-precision position system with its simple control scheme. However, An equality between two airgap lengths Is a necessary condition for its high performance. If a little difference between two airgaps is existed, unbalanced normal force and undesirable vibration will be generated. Additionally, even though two airgap lengths are absolutely same, undesirable vibration can be generated because the direction of instantaneous normal force on mover is changed according to excitation methods. An effect of inequality of two airgap lengths is presented in this paper. Distribution of airgap permeance vs. relative displacement is analyzed by two dimensional finite element method. Excitation From this results, current waveforms to reduce the undesirable vibration is proposed.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2473-2475
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• 2001

In trajectory tracking methods, the error values of current position and velocity are compensated to follow the given reference path and velocity. The path tracking for a wheeled mobile robot is treated in this paper. It is very difficult to implement stable trajectory tracking algorithms because mobile robots have kinematically non-holonomic constraints. For solving this problem, a velocity controller is presented in this paper. This velocity controller is designed by a PID controller which could be easily employed. In this case, velocity errors caused by system uncertainties or internal and external disturbances could exist. A neural network is used for compensating the velocity errors. Input variables of this neural network compensator are defined by differences between the velocities of the posture controller and the real velocities of the mobile robot. Simulation results show the effectiveness of the proposed controller.