• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.12
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• pp.1209-1218
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• 2016

In order to safely and speedily transport a load such as a large glass plate using four electric cylinders, the synchronous error outside the permitted range should not be continuously generated between the cylinders. In this study, a methodology of synchronous control which can be applied to synchronization of four or more cylinders is developed. The synchronous control system based on the decoupling structure is composed of a reference model, position and synchronous controllers in the respective cylinders. The reference model is used for calculating the decoupled synchronous error and control input for the each cylinder. The position controller of I-PD type is designed in order that the cylinder may follow the reference signal without overshoot and input saturation. And the synchronous controller of lead compensator is designed to achieve stable and accurate synchronization through loop shaping approach. Finally, the simulation results show that the synchronization between the four cylinders can be quickly and stably while each cylinder rod is transferred to the target point under torque disturbance.

• ETRI Journal
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• v.32 no.2
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• pp.345-347
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• 2010

In this letter, we present a new speech hash function based on the non-negative matrix factorization (NMF) of linear prediction coefficients (LPCs). First, linear prediction analysis is applied to the speech to obtain its LPCs, which represent the frequency shaping attributes of the vocal tract. Then, the NMF is performed on the LPCs to capture the speech's local feature, which is then used for hash vector generation. Experimental results demonstrate the effectiveness of the proposed hash function in terms of discrimination and robustness against various types of content preserving signal processing manipulations.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.480-483
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• 2004

This paper, we present the evaluation of outage probability on the SNR under the overlapped carrier allocation scheme in the reverse link with imperfect power control of a cellular CDMA system, which is base on using Gaussian approximation. In numerical results, the band limited pulse generated by square-root of raised consin pulse shaping filters (SRRC) of the transmitted signal is investigated and compared in conventional FD/CDMA and OC-CDMA of the outage probability. It will be also show that the outage probability can be improved by overlapping of carriers. We use error statistics to model the intra-cell interference and evaluate the impact of different mobiles velocity and number of resolvable paths on the system performance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.877-880
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• 2001

This paper presents the new linear motion device so called "inch-worm" which gets large displacement by incrementally summing small displacements of PZT actuators. Dynamics stiffness of inch-worm is generally low compared to its driving condition due to the requirement of inch-worm like small size and light weight. This low stiffness may degenerate the positional precision of inch-worm. An inch-worm is realized using three PZT actuators, a monolithic moving device and a guide way frame. Driving input signal is shaped to reduce the residual vibration of inch-worm by LQG controller and cycloid step input. The practical feasibility of inch-worm is also examined by running test.ning test.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.9
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• pp.14-23
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• 1993

In this paper, we present analysis results of various intermodulation products (IMPs) evaluation methods previously proposed for nonlinear systems. The results indicate that out of these methods, Fuenzalida and Simbo's method is the best for efficient evaluation of IMPs. Also, we present a detailed mathematical analysis of IMP and show how to apply the equations related to IMP to actual program implementations with examples. In this paper, we newly introduce three methods to reduce the IMP calculation time and improve the accuracy of the outputs :1) TWTA curve fitting method by LS (Least Square), 2) IMP evaluation technique which is based on a look-up table 3) Gaussian spectral shaping for PSK signal instead of convolution. The IMP evaluation results obtained by the new approaches introduced in this paper resulted in a good match with the published outputs in the open literature and showed improved performance especially in the TWTA curve .

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.411-414
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• 2000

Optical Triangulation Probes (OTPs) are widely used for their simple structure. high resolution, and long operating range. However, errors originating from speckle, inclination of the object, source power fluctuation, ambient light, and noise of the detector limit their usability. In this paper, we propose new design criteria for an error-reduced OTP. The light source module for the system consists of an incoherent light source and a multimode optical fiber for eliminating speckle and shaping a Gaussian beam Intensity profile. A diffuse-reflective white copy paper, which is attached to the object, makes the light intensity distribution on the change-coupled device(CCD). Since the peak positions of the intensity distribution are not related to the various error sources, a sub-pixel resolution signal processing algorithm that can detect the peak position makes it possible to construct an error-reduced OTP system

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.374-381
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• 2005

The ability to provide quality power has become a significant issue in power systems. The main causes of poor power quality are harmonic currents, poor power factor, supply-voltage variations, etc. A technique of achieving both active current distortion compensation, power factor correction and also mitigating the supply-voltage variation (sag or swell) at the load side is presented in this paper. The operation and rating issues of the proposed Single-phase Unified Power Quality Conditioner are also highlighted. To reduce the total cost while simultaneously increasing the performance, the system is fully digitally controlled using the fixed-point TMS320F240 digital signal processor. The performances of the UPQC, which is composed by shunt and series PWM controlled-converters, have been verified on a laboratory prototype.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.9
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• pp.650-656
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• 2004

This paper presents block and timing diagrams of the DWA(data weighted averaging) to optimize a feedback time delay of the sigma-delta modulator. Through the Matlab modeling, the optimized coefficients of the integrators are obtained to design the modulator. And then the fully differential SC integrators, feedback DAC, 9-level quantizer, and DWA are designed by considering the nonideal characteristics of the modulator. The designed second-order multibit modulator is fabricated in a 0.35$\mu\textrm{m}$ CMOS process. The designed modulator achieves 73dB signal-to-noise ratio and 72dB dynamic range at 1.2Vp-p 585kHz input singal and 52.8MHz sampling frequency.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.267-271
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• 2010

Photovoltaic system simulator is under being developed for the performance test of Power conditioning system (PCS). The photovoltaic system simulator is required to emulate real system, which can be obtained by fast response controller. In this paper, we suggest a robust control method as a tool to design the simulator controller. The performance of the controller is determined by weighting functions, sensitivity function $W_1$ complementary sensitiviey function $W_3$, and a control signal shaping function $W_u$. Experimental results show that robust control method is promising for obtaining better performance of the photovoltaic system simulator.

• Journal of Advanced Navigation Technology
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• v.7 no.1
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• pp.6-13
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• 2003

In this paper, a non-coherent code tracking loop is designed for 3GPP HSDPA MODEM and its performance is analyzed in terms of steady-state jitter variance and transient response characteristics. Analytical closed-form formula for steady-state jitter variance is first derived for AWGN environments as a function of pulse-shaping filter, timing offset, signal-to-interference ratio, and loop bandwidth. Also obtained is the transient response characteristic of a tracking loop. Finally, the performance of the designed tracking loop is confirmed by computer simulations.