• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.902-906
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• 1990

On-line robust control based on a stability index for time-delay systems has been developed. The purpose of the proposed design algorithm is to on-line tune a filter in the control loop. The problem of robust control with an incorrect given bound on the modeling error is investigated. Illustrative examples are presented to show the promise of the proposed method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.8
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• pp.1777-1783
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• 2013

We do research on the simulation of Doppler effect from a target's moving under the sea by Transmission Line Matrix modeling which is one of numerical methods on time domain. To implement the effect, the input signal was entered at a moving node according to a moving target's moving speed. The result had maximum 2.47% error compared with the theoretical value. And from simulation results with speed control of a moving target, we could also obtain resonable results within 0.63% error range.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1837-1843
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• 1997

This study experimentally demonstrates the use of active muffler attached to the automotive exhaust system to reduce exhaust noise. For improving the signal to noise ratio in the process of estimation of secondary path transfer functions, the on-line algorithm that conventional inverse modeling is combined with adaptive line enhancer is used as the control algorithm. Active muffler is designed that the primary noise and the control sound are propagated as a plane wave in the outlet. Therefore, the error microphone could be placed out of the tail pipe center of a high temperature and the radiation noise to the outside could be reduced in the whole area around the outlet. The control experiment for reducing exhaust noise with active muffler is implemented during run-up at no load. From the experimental results presented, compared with the conventional off-line method, the proposed on-line method is capable to acquire a reduction of exhaust noise above 5 dB in overall sound power level.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.586-593
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• 2017

Modeling busbar distribution system as a transmission line is an important subject of power line communication in the smart grid concept. This requires extraction of busbar RLGC parameters, accurately. In this study, a comparison is made between conventional and modified method for the aspect of optimum RLGC parameters extraction in the 1 MHz to 50 MHz frequency band. The usefulness of these methods is shown both in time and frequency-domain analysis. The frequency-domain analyzes show that the inherent power of modified method can eliminate the errors especially due to the discontinuities arise in conventional method. This makes the modeling approach of modified method more advantageous for the busbars due to its robustness against disturbances in the S-parameters measurements which cannot be eliminated with the calibration procedure. On the other hand, time-domain simulations show that the transmission line representation of the modified method is closer to physical reality by handling causality issues.

• Journal of Hydrospace Technology
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• v.2 no.1
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• pp.41-54
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• 1996

Sculptured surface structures such as ship hulls are traditionally formed up to the required double curved shape by line heating method. The nature of the line heating process is a transient thermal process, followed by a thermo-elastic-plastic stress field. The permanant shape is dependent on many factors involved in the process, Among them are torch speed and path, supplied heat type and amount , and plate size. Thus, the work is essentially leaded by experts with lots of experiences. However, in order to effectively improve productivity through automation, each factor should be clearly examined how much it affects the final shape. This can not be done only by experiments, but can be achieved by a mechanics-based approach. In this paper, we propose a conceptual configuration for plate forming system, and then present simulations of the line heating process with numerical data in practices and suggest a computerized process of the line heating for practical applications. The modeling of heating torch, water cooling, and the plate to be formed is proposed for the finite element analysis after the mechanics of line heating is studied. Parametric studies are given and discussed for the effects of plate thickness, torch speed and initial curvature in forming a saddle typed surface.

• The Journal of Information Technology
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• v.7 no.3
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• pp.1-10
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• 2004

Considerable efforts has been recently devoted to the determination of accurate channel models for the Power Line environment, both for the indoor and outdoor cases. The common denominator and limitation of the known and previously published models is the particular type of approach followed. In this paper is concerned with a power line channel modeling for the more fast and efficiently power line communication experiment. A capacitor load channel simulator is a essential equipment in the power line modem development for indoor network. We accomplished a channel modelling by the frequency response method about the total 224 capacitor load cases. On the basis of this measurement modeling it is here revealed that the PLC is a more deterministic media that commonly believed.

• Journal of the Korea Society of Computer and Information
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• v.18 no.8
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• pp.1-8
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• 2013

This paper proposes an effective parallel implementation of a physical modeling synthesis of guitar on the GPU environment. We used appropriate filter coefficients and adjusted the length of delay line for each open string to generate 44,100 six-polyphonic guitar sounds (E2, A2, D3, G4, B3, E4) by using physical modeling synthesis. In addition, we analyzed the physical modeling synthesis algorithm and observed that we can exploit parallelism inherent in the length of delay line. Thus, we assigned CUDA cores as many as the length of delay line and effectively implemented the physical modeling synthesis using GPU to achieve the highest performance. Experimental results indicated that synthetic guitar sounds using GPU were very similar to the original sounds when we compared their spectra. In addition, GPU achieved 68x and 3x better performance than high-performance TI DSP and CPU, respectively. Furthermore, this paper implemented and evaluated the performance of multi-GPU systems for the physical modeling algorithm.

• Transactions of The Korea Fluid Power Systems Society
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• v.1 no.2
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• pp.20-25
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• 2004

In this study, a position control characteristics of pneumatic cylinder with transmission line is analyzed. Dynamic characteristics of transmission line using compressible fluid is changed by the flowing stiles of the fluid the diameter and the length of the line. But, the effect of the change of dynamic characteristics of transmission line by the flowing states on the position control characteristics can be neglected because of the friction force of the pneumatic cylinder. So, We assume that the position control characteristics is affected by the diameter and length of the transmission line. The experimental results according to the change of parameter of the transmission line show that the relation between the parameter of the transmission line and the position control characteristics of pneumatic cylinder driving system with the transmission line.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1935-1944
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• 2018

With the increase of the production of energy from renewable, it becomes important to look at techniques to store this energy. Therefore, a single winding bearingless flywheel motor (SWBFM) specially for flywheel energy storage system is introduced. For the control system of SWBFM, coupling between the torque and the suspension subsystems exists inevitably. It is necessary to build a reasonable radial force mathematical model to precisely control SWBFM. However, SWBFM has twelve independently controlled windings which leads to high-order matrix transformation and complex differential calculation in the process of mathematical modeling based on virtual displacement method. In this frame, a Maxwell tensor modeling method which is no need the detailed derivation and complex theoretical computation is present. Moreover, it possesses advantages of universality, accuracy, and directness. The fringing magnetic path is improved from straight and circular lines to elliptical line and the rationality of elliptical line is verified by virtual displacement theory according to electromagnetic torque characteristics. A correction function is taken to increase the model accuracy based on finite element analysis. Simulation and experimental results show that the control system of SWBFM with radial force mathematical model based on Maxwell tensor method is feasible and has high precision.

• The Journal of the Acoustical Society of Korea
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• v.22 no.1E
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• pp.33-42
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• 2003

Kuo et al proposed an on-line method for an adaptive prediction error filter for improving secondary path modeling performance in the modeling method of the secondary path. This method have some disadvantages, namely having to use additive noise with the result that noise control performance is not good since it is focused on the estimated performance of the secondary path. In this paper, we proposes a modified Kuo model using gain control parameter and delay. It uses a reference signal for additive noise to improve the problems in the existing Kuo model.