• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.10
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• pp.1215-1221
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• 1999

A high speed digital distance relaying algorithm based on a Wavelet Transformation is proposed. To obtain stable phasor values very quickly, first, a lowpass filter which has low cutoff frequency is used. Secondly, db2(Daubechies 2) Wavelet which has the data window of 4 samples is used. A FIR filter which removes the DC-offset component in current relaying signals is applied. In accordance with a series of tests, the operation time of the relaying algorithm is less than 3/4 cycles after faults in a 80 [km], 154[kV], 60[Hz] over-head transmission line system.

• ETRI Journal
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• v.29 no.4
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• pp.470-476
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• 2007

In this paper, a versatile three-input five-output universal capacitor-grounded voltage-mode filter is proposed. The circuit employs two differential voltage current conveyors as active elements together with two grounded capacitors and four resistors as passive elements. The proposed configuration can be used as either a single-input five-output or three-input two-output. Unlike the previously reported works, it can simultaneously realize five different generic filtering signals: lowpass, bandpass, highpass, bandreject, and allpass. It still maintains the following advantages: (i) the employment of all grounded capacitors, (ii) no need to employ inverting-type input signals, (iii) no need to impose component choice, (iv) orthogonal control of the resonance angular frequency ${\omega}_o$ and the quality factor Q, and (v) low active and passive sensitivity performances.

• Tribology and Lubricants
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• v.17 no.1
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• pp.33-39
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• 2001

A method of calculating wear volume is developed using the signal processing technique. The lowpass filter with Fourier transform and the “windowing” are implemented in the method. User-defining feature is also included in determining the cutoff frequency of the low-pass filter and the baseline for the volume integration. Commercial software, MatLab, is used for the programming. Since the method uses the original wear data without simplifying the wear shape, it can give a further accurate result than the previously utilized methods, which often adopted the simplification. It becomes further powerful if the contacting body has a general shape rather than that gives well-formed surface traction (e.g., the Hertzian). The validation of applying the average surface roughness, Ra, to the “windowing” and the baseline for volume integration is discussed.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.265-268
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• 2003

In this paper, we introduce the SIR typed bandpass filters in CPW structures for shifting spurious harmonic frequency into higher frequency band. And we proposed the effective feed structures for suppressing spurious frequency in the SIR typed CPW bandpass filters. The designed folded feed structures have lowpass filtering characteristic. They are very effective feed types in the CPW bandpass filters for suppressing harmonics. The measured results of the CPW bandpass filter with folded feed line shows that it has suppressed and wide out-of-band up to 5.8fo.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.1
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• pp.11-21
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• 1989

In this paper, a GMSK modulator was implemented with a gaussian lowpass filter using digital signal processing, a phase integration, D/A convers and auxiliary circuits. The relatively narrow bandwidth of power spectrum of the GMSK modulator is observed when the cut off frequency (B T) of the gaussian baseband filter is varied. In a demodulator, a discriminator type circuit is used. Using the above degital radio GMSK modem, BER is theoretically derived and experimentally measured when 16Kbps PRBS data is transmitted under Rayleigh fading and additive white gaussian noise conditions.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.7
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• pp.855-862
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• 1999

A high speed digital distance relaying algorithm based on a least square error method is proposed. To obtain stable phasor values very quickly, first, a lowpass filter which has very short transient period and no overshoot is presented. Secondly, the least square error method having the data window of 3 samples is used by applying a FIR filter which removes the DC-offset component in current relaying signals. Test results show that the proposed distance relaying algorithm detects most of internal faults within a half cycle after faults in a 154[kV] overhead transmission line system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4745-4750
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• 2012

In this paper a $6^{th}$ 1MHz~30MHz bandpass filter for Power line communication(PLC) modem receiver is designed using current mode synthesis method which is good to design the low-voltage and low-power filter. The designed bandpass filter is composed of cascade connecting between $3^{rd}$ Butterworth highpass filter and $3^{rd}$ Chebychev lowpass filter. As a core circuit in the current-mode filter, a current-mode integrator is designed with new architecture which can improve gain and unity gain frequency of the integrator. The gain and the unity gain frequency of the designed integrator is each 32.2dB and 247MHz. And the cutoff frequency of the designed $6^{th}$ bandpass filter can be controlled to 50MHz from 200KHz according to controlling voltage and the power consumption is 2.85mW with supply voltage, 1.8V. The designed bandpass filter was verified using a $0.18{\mu}m$ CMOS parameter.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.418-428
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• 2007

In the calculation of wave propagation by Boussinesq equation model, it is very common to experience numerical noises generated from nonlinear interaction and breaking wave occurrence, and the numerical solution is rapidly diverged unless the noises are properly controlled. A comparative study was here undertaken for the characteristics of three different lowpass filters (FFT filter, Gaussian filter and Shapiro filter) which are all designed to be applied to the interim results of numerical calculation. The numerical results obtained with application of respective filter techniques were compared with the results of an existing hydraulic experiment for the aspects of noise suppression, conservation of main signal and altering time. The results show that the Shapiro filter can be best applied with optimal choices of its element number, pass number and filtering tune interval. The combination of the number of filter element off, pass number of 50 or less, and application interval of 100 to 200 time steps generally showed good performance in both accuracy and efficiency of the numerical calculation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.5
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• pp.84-95
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• 2011

In this paper, we present a deblocking algorithm that removes grid and staircase noises, which are called "blocking artifacts", occurred in the compressed satellite images. Particularly, the given satellite images are compressed with equal quantization coefficients in row according to region complexity, and more complicated regions are compressed more. However, this approach has a problem that relatively less complicated regions within the same row of complicated regions have blocking artifacts. Removing these artifacts with a general deblocking algorithm can blur complex and undesired regions as well. Additionally, the general filter lacks in preserving the curved edges. Therefore, the proposed algorithm presents an adaptive filtering scheme for removing blocking artifacts while preserving the image details including curved edges using the given quantization step size and content analysis. Particularly, WLFPCA (weighted lowpass filter using principle component analysis) is employed to reduce the artifacts around edges. Experimental results showed that the proposed method outperforms SA-DCT in terms of subjective image quality.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.9
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• pp.46-51
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• 2009

This paper propose the new approach of the quantity effect by high efficiency inductor characteristic to the harmonic suppression of the lowpass filter. We applied the reliable de-embedding process in order to extract the precise elements values. Moreover, for the effective its application and comparison, the variable stepped impedance low pass filters with a same specification are designed. The proposed procedure is expected to handle the overall filter performance and to construct a synthesized equivalent circuit from its determined specification.