• Journal of Institute of Control, Robotics and Systems
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• v.8 no.3
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• pp.193-198
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• 2002

In this paper, we Propose a PD+I fuzzy controller using an error-accumulating applying factor. In fuzzy control, analytical study was done formerly, in which fuzzy control can be classified by PD type and PI type, and also the study for getting merits of both types was done, too. But the mixed type has a complex structure and many parameters. The proposed fuzzy controller is 2-input 2-out-put and PD type fuzzy control is used as a basic structure. And the proposed controller annihilates a steady-state error and improves transient responses because of using the error-accumulating applying factor which is determined in the real time along the current state of controlled process. Futhermore it is easy to tune the system because of decreasing the number of scaling factors and the I type controller with resetting resolves the integral wind-up problem. Finally we apply the proposed scheme to various plants and show the performance betterment.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.6
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• pp.641-646
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• 2014

In this paper, we propose a controller for a ball and beam system which reduces the measurement error effect under AC and DC noise. The ball and beam system measures data through a sensor. If sensor noise is included in a controller via the feedback channel, the signal is distorted and the entire system cannot work normally. Therefore, some appropriate action for the measurement error effect is essential in the controller design. Our controller is equipped with a gain-scaling factor and a compensator to reduce the effect of measurement error in the feedback signal. Effectively, our proposed controller can reduce the AC and DC noise of a feedback sensor. We analyze the proposed controller by Laplace transform technique and illustrate the improved control performance via an experiment for a ball and beam system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.887-892
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• 2003

In this paper, we propose a simple scaling algorithm for CDMA mobile communications where a voice traffic signals are transmitted by individual one of several data rates at every frames. The traditional method is based on using look-up table called SMT(symbol metric table), but the proposed algorithm is real-time direct scaling method through simple bit manipulations without lookup table. The bit error rate performance is calculated by computer simulation over AWGN and Rayleigh fading channels. From the results, it is shown that the proposed algorithm outperforms the traditional SMT method on Rayleigh channel by 0.3∼0.8dB, while achieving the less H/W complexity.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.491-497
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• 1993

In MIMO design, input and output units are different from each other. By this reason, the effect of larger units to smaller one is not trivial and there is no method of proper scaling, optimal scaling. In this paper, robust stability of MIMO LQG/LTR design are analised when the plnat inputs and outputs are scalled. The upper bound of model error to guarantee the robust stability is obtained, and gain margin and phase margins are computed with respect to scalling matrices.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.53-56
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• 2000

본 논문에서는 컬러이미지의 스케일링(scaling)을 위해 경사투영방법을 사용하여 기본적인 보간방법, 최소자승근사(least square approximation)의 결과들과 비교하여 보았다. 경사투영방법은 최소의 근사오차(approximation error)를 제공하는 수직투영(orthogonal projection)방법과 유사한 결과를 제공하며 전처리 필터 디자인에 자유성을 부여하고, 좀 더 일반화된 형태의 보간 방법이다. 사용된 방법을 기본적인 보간법들과 비교하여 보았을 때 더 좋은 PSNR의 결과를 얻을 수 있었으며 최소자승근사 방법과 유사한 결과들을 얻을 수가 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.419-424
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• 2015

The Decision-directed (DD) algorithm is known to be not effective to initialize a blind equalizer in the channel conditions when the eye diagram of received signals is completely closed because it can not open the eye diagram enough. In this paper, we propose a new error to replace the error of the conventional DD algorithm. The new DD error is the conventional DD error scaled by the modulus of symbol decision, new DD algorithm using this error is effective to open the closed eye diagram in early stage of equalization unlike the conventional DD. The new DD algorithm appling the new error is showed excellent convergence characteristics as compared to the CMA widely used in blind initialization, particularly, is useful for equalization of signals having multimodulus. The performance of the new DD algorithm is verified through the simulation for the higher-order QAM signals.

• Journal of the Korea Computer Industry Society
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• v.5 no.9
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• pp.993-1004
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• 2004

We propose the method for kinematic and dynamic modeling and Path-tracking of four-wheeled mobile robots with 2 d.o.f having the limited drive-torques. Controllability of wheeled-mobile robots is revealed by using the kinematic model. Instantaneously coincident coordinate system, force/torque propagation and Newton's equilibrium law are used to induce the dynamic model. When drive-torques generated by inverse dynamics exceed the limitation, we make wheeled-mobile robots follow the reference path by modifying the planned reference trajectory with time-scaling. The controller is introduced to compensate for error owing to modeling uncertainty and measurement noise. And simulation results prove that the method proposed by this paper is efficient.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.486-490
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• 2002

When the fuzzy controller apply to a real plant, We have not excepted result of a satisfactory control by modeling error and lacking information about an plant. In this case, we have to adjust the scale factors for improvement of the control performance and this method need a lot of time and cost for perform a trial and error. In this paper, we proposed the fuzzy controller with the automatic adjustment of scaling factors. It was improve upon the control performance using a adequate scale factor by fuzzy logic and normalizer. As the results of simulation through the second order plant, we confirmed that the proposed the fuzzy controller within the function of automatic scale get a good response compare with the fuzzy controller within the fixed scale factor.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.80-84
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• 2001

When the fuzzy controller apply to a real plant, We have not excepted result of a satisfactory control by modeling error and lacking information about an plant. In this case, we have to adjust the control factors for improvement of the control performance and this method need a lot of time and cost for perform a trial and error. In this paper, we proposed the fuzzy regulator with the automatic adjustment of scaling factors. It was improve upon the control performance using a adequate scale factor by fuzzy inference. We implemented the controller using the DSP processor and applied in a hydraulic servo system. And then we observed an experimental results.

• Journal of electromagnetic engineering and science
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• v.13 no.3
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• pp.158-164
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• 2013

This paper expands a previously proposed optimized higher order (2, 4) finite-difference time-domain scheme (H(2, 4) scheme) for use with lossy material. A low dispersion error is obtained by introducing a weighting factor and two scaling factors. The weighting factor creates isotropic dispersion, and the two scaling factors dramatically reduce the numerical dispersion error at an operating frequency. In addition, the results confirm that the proposed scheme performs better than the H(2, 4) scheme for wideband analysis. Lastly, the validity of the proposed scheme is verified by calculating a scattering problem of a lossy circular dielectric cylinder.