• Journal of Power Electronics
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• v.9 no.3
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• pp.403-409
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• 2009

Automatically tuned passive filters can improve power quality to a great extent in power systems. A novel three-phase shunt auto-tuned filter is designed to effectively compensate source current harmonics and to provide reactive power required by the non-linear load, which draws a highly reactive, harmonic-rich current from the supply. An artificial neural network (ANN) based controller selects filter component values in accordance with reactive power requirement and harmonic compensation. Traditional passive filters are permanently connected to the system and draw large amounts of source current even under light load conditions. By using auto-tuned filters, the passive filter components can be controlled according to load variations and, hence, draw only required source currents. The selection is done by the ANN with the help of a properly tuned knowledge base to provide instantaneous compensation using a digital controller.

• Journal of the Korean Institute of Navigation
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• v.24 no.5
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• pp.443-450
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• 2000

Before some experiments were carried out with analog bandpass filter which used for filtering the noise included in sound source signal. And this filter was constituted by condenser, register and operational amplifier. Hut these elements made the phase characteristics to differentiate in each sensing channel and cause a little of measurement error. We made new measurement system that was substituted digital filter for the analog filter in order to develop the optimal system which could find the time delay between each sensors with high accuracy. This paper describes the new system's constitution and the function of each parts. Specially three digital filters were designed and applied to the digital signal processing Part. And a series of experiments were carried out with the source＇s distance 9.53meters and the random bearing interval within the limits of $0^{\circ}$ ~ $180^{\circ}$. As a result, we have recognized that the accuracy of measurements were differentiated by the methods what kind of digital filter were adopted. And we have confirmed the facts that IIR LPF was suitable for sound source's bearing measurement and FIR LPF reduced the range measurement error.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.697-704
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• 2008

Stormwater runoff from urban road area as non-point source has a tendency of including lots of pollutants at initial rain period. Recently, there are several cases of having installed treatment facilities for reducing pollution discharge from the impervious cover in urban area to prevent watershed environment from getting worse. The filtration type among non-point source treatment systems has been known as one of the most efficient system for treatment of non-point source pollutants. Therefore, various kinds of filter media such as expanded polypropylene(EPP), granular activated carbon, zeolite, perlite, illite, sand, gravel has been developed. This study was conducted to verify performance and hydraulic characteristics of filter media as measures for non-point source. The experiment was carried out to evaluate applicability and variation of 4 kind of most popular filter media(EPP, GAC, Zeolite, Perlite) in headloss with elapsed time and influent flow rate and to obtain data base that could be used to establish management plan for road runoff treatment. In experiment by tap water, it showed that EPP and perlite those are floatable materials showed stable operating performance and lower headloss than the others.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.1
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• pp.88-98
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• 2012

In this paper, the relationship between the bandwidth (BW) and power efficiency of a source follower based (SFB) filter is quantitatively analyzed, and a design methodology for a SFB filter for optimized BW - power consumption is introduced. The proposed design methodology achieves a maximum BW at a target quality (Q) factor for the given power consumption constraint by controlling design factors individually. In order to achieve the target BW from the maximized BW, a tuning method is introduced. Through the proposed design methodology, a fourth order Butterworth filter was implemented in 0.18 ${\mu}m$ CMOS technology. The measured BW, power consumption, and IIP3 are 100 MHz, 33 ${\mu}W$, and 9 dBm, respectively. Compared with other filter structures, the measured results show high BW - power efficiency.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.5
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• pp.386-393
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• 2001

A series active power filter compensating current harmonics and unbalanced source voltages in a 3phase-3wire power system is presented. The system is composed of series active power filter and shunt passive filters that are tuned at 5th and 7th harmonics. The proposed series active power filter improves harmonic compensation characteristics of the shunt passive filters, reduces source side harmonic currents and compensates the unbalanced source voltages. In the proposed algorithm, compensation voltage for harmonic reduction is calculated by a performance function, and compensation voltage for the unbalanced source voltage is calculated based on the synchronous reference frame. Some results obtained from the experimental model using the proposed method are Presented to demonstrate and confirm its validity.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.5
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• pp.221-229
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• 2003

This paper suggests a control algorithm of 3-phase 3-wire series active power filter. This suggested algorithm can compensate source harmonics and reactive power in 3-phase 3-wire power distribution systems. These harmonics are generated by nonlinear loads such as diode rectifiers and thyristor converters. This control algorithm extracts a compensation voltage reference from performance function without phase transformation. Therefore, this control algorithm is simpler than any other conventional control algorithms. 3-phase 3-wire series active power filters which have a harmonic voltage source and a harmonic current source are manufactured and experiments are carried out to verify the effectiveness of suggested control algorithm.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1077-1080
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• 1992

In this paper suggested methods for current control in active filter are using the triangular carriers which were composed of independently generated threefold carriers and controllable current source which compensates the harmonics generated independently from the types of the load with instantaneous amplitude adjusting from the maximum magnitude of the compensating currents. And the 2-nd order high pass passive filter connected to the source finally supplies pure sinusoidal waves by suppressing the residual harmonics which cannot removed by the active filter. As the typical load which generates the harmonics, a rectifier was set and the system was also designed by simulations and implementations.

• Journal of Navigation and Port Research
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• v.28 no.2
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• pp.135-140
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• 2004

A purpose of developing a sound source tracking system in this paper is to reduce the noise efficiently from the received signal by microphone array and measure the signal's time delay between the microphones. I have applied the wavelet analysis algorithm to the system and calculated the sound source's relative position For the performance evaluation, I have compared with the results of utilizing the digital filtering methods based on the FIR LPF using Kaiser window function and the inverse Chebyshev IIR LPF. As a result, I have confirmed the fact that 'time-scale' filter using inverse discrete wavelet transform was suitable for this system.

• Journal of Korean Society on Water Environment
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• v.30 no.2
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• pp.159-165
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• 2014

Vegetative Filter Strip (VFS) is one of effective Best Management Practices (BMPs) to prevent sediment-laden water problem, is installed at the edge of source area such agricultural area so that sediment occurred in source area is trapped by VFS before it flow into stream or river. Appropriate scale of it needs to be simulated before it is installed, considering various field conditions. In this study, a model using VFSMOD-w model and Genetic Algorithm to determine effective VFS length was developed, it is available to calibrate input parameter related to source area sediment yield through thousands of VFSMOD-w simulations. Useful DBs, moreover, are stored in the model so that very specific input parameters can be used with reasonable values. Compared simulated values to observed data values for calibration, R2 and Nash-Stucliffe model efficiency coefficient were 0.74 and 0.65 in flow comparison, and 0.89 and 0.79 in sediment comparison. The model determined 1.0 m of Filter Length, 0.18 of Filter Slope, and 0.2 cm of Filter Media Spacing to reduce 80% of sediment by VFS. The model has not only Auto-Calibration module also DBs for specific input parameters, thus, the model is expected to be used for effective VFS scale.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.180-185
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• 1989

In the current source type active power filter, the DC current source is implemented using an inductor with large inductance by maintaining the inductor current constantly. In this case, to compensate the loss of the switching devices of the power converter and the inductor, some real power should be supplied to the filter from the source. This process is analyzed through the equivalent circuit which expresses the loss of the switching devices and the inductor with the equivalent resistor R. This work discusses the validation of this DC side equivalent circuit and points out the problems, through the experiments using the experimental active power filter with 220V, 10KVA ratings, and suggests a more accurate equivalent circuit which puts the saturation voltage of the power transistors and the threshold voltage of the diodes into consideration.