• Journal of Power Electronics
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• v.11 no.6
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• pp.904-913
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• 2011

Previous publications regarding the design and specifications of input filters for STATCOMs usually deal with the input filter only, and seldom pay any attention to the influence of the input filters on the performance of the STATCOM systems. A detailed analysis of the influences of input filters on the stability of STATCOM systems and the corresponding design considerations are presented in this paper. Three types of input filters, L filters, LC filters, and LCL filters, are examined separately. The influences of the parameters of input filters on system stability are investigated through frequency domain methods. With direct current control taken as the major control strategy for the STATCOMs, the different situations when adopting different current detection points are covered in this analysis. A comparison between LC filters and LCL filters is also presented with optimized filter parameters. Based on the analysis, the phase margin, as one of the design considerations for the different types of input filters under different current detection schemes, is discussed. This leads to filter parameters that are different than those of the traditional design. Hardware experimental results verify the validity of the above analysis and design.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.817-822
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• 1992

Distortion analysis of digital filters for the ECG signal processing is presented. Several band pass and band reject filters are designed for the analysis. Computer simulations are performed to compare the distortions of the Butterworth type filters and linear phase optimal fitters. The designed filters are applied to power line interference cancelling in ECG signals.

• Journal of Biomedical Engineering Research
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• v.14 no.2
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• pp.137-145
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• 1993

Time domain analysis as well as frequency domain analysis of signal conditioning filters is very useful for practical applications. Time domain analysis of digital filters for noise cancelling in ECG signals is presented. Several band pass and band reject filters are designed for the analysis. Computer simulations are performed to compare the distortions of the Butterworth type filters and linear phase optimal FIR filters which are widely used for ECG signal processing. Band reject filters are applied to power line interference cancelling in ECG signals.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.362-368
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• 2009

The SA filters encompass a large class of filters based on order statistics as well as linear FIR filters. The class of SA filters is defined as a multi-stage filters whose output is linear combination of nonlinear(minimum, maximum, exclusive-OR) sub-filter outputs. According to the lust stage nonlinear sub-filters, SA filters are called SAMAX, SAMIN, and SAXOR filters. In this paper, optimal SAMAX and SAMED filters are designed for images corrupted by biased noise. The performance analysis of this experiment shows that SAMAX filters outperforms SAMED filters for biased noise. In the case of un-biased noise, the SAMAX and SAMED filters give the same performance. This result leads us to a new guideline in the application of SA filters.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.70-73
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• 1993

Design as well as Distortion analysis of signal conditioning filters is very useful for practical applications. Distortion analysis of digital filters for wave forms detection in ECG signals is presented. Several band pass and band reject filters are designed for the analysis. Computer simulations are performed to compare the distortions of the Butterworth type filters and linear phase optimal FIR filters which are widely used for ECG signal processing.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.89-94
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• 2006

In order to increase the signal-to-noise ratio in multi-component seismic data, we developed new polarization filters based on the method of multicomponent complex trace analysis. Unlike the previous polarization filters, the present filters separately compute linear and elliptic components at each time sample using amplitude ratio of horizontal and vertical components of body waves and ellipticity of Rayleigh waves. The polarization filters work ideally even with low S/N data. Application of the filters to both synthetic and real seismic data shows that Rayleigh waves of elliptic motions are effectively eliminated and both P and S waves of linear motions are well separated each other.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1134-1138
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• 2008

Electret filter media are used in general ventilation filters, disposable respirators, vehicle cabin filters, vacuum cleaners and room air cleaners. There are basic mechanisms of interception, inertial impaction, diffusion, gravitational settling, electrostatic attraction by which an aerosol particle can be deposited onto a fiber in a filter. The ability of fine particle removal strongly depends on the electrostatic forces between particles and polarized fibers. Thus, the stability of the fiber polarization is a major factor in the reliability of electret filters. In this study, electrical properties and filtration performance of electrospun filter media are quantitatively investigated. Electrical properties of electrospun filters have been studied on surface charge potential and surface charge density. Also the filtration performance of the electret filters are evaluated on collection efficiency. Electrospun filters show same collection efficiency with low pressure drop compare to commercialized HEPA filters. Surface charge potential and surface charge density of electrospun filters are increased with increasing applied voltage. Also collection efficiency of electrospun filters is increased with increasing surface charge potential and surface charge density.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.10
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• pp.630-638
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• 2005

In FIR (Finite Impulse Response) filter applications, Nth-band F]U digital filters are known to be important due to their reduced computational requirements. The conventional methods for designing F]U filters use iterative approaches such as the well-known Parks-Mcclellan algorithm. The Parks-Mcclellan algorithm is also used to design Nth-band FIR digital filters. But a disadvantage of the Parks-Mcclellan algorithm is that it needs a good amount of design time. This paper describes a direct design method for Nth-band FIR Filters using Chebyshev polynomials, which provides a reduced design time over indirect methods such as the Parks-Mcclellan algorithm. The response of the resulting filter is equiripple in passband. Our proposed method produces a passband response that is equripple to within a minuscule error, comparable to that of the Parks-Mcclellan algorithm.

• Journal of Korean Society on Water Environment
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• v.37 no.5
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• pp.398-404
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• 2021

The use of water purifiers has been increasing every year due to increased drinking water safety concerns raised by the water pollution accidents occasionally reported. Currently, more than 10 million water purifiers have been distributed in Korea, and the estimation of the purifier sales reaches two million units per year. As a result, the number of used water purifier filters that must be replaced on a regular basis has gradually increased. However, regardless of the considerations for the capacity of used filters remaining, water purifier filters were replaced and collected at regular intervals. The high cost of disposal of the used filters by landfill or incineration were required. Thus, in this study, the current status and trends of recycling technologies for used water purifier filters were reviewed. It is noted that there was insufficient statistical data to understand the current status of the difference between the number of used water filters discarded and the number of those recycled. Most studies on the recycling of old water purifier filters have concentrated on pretreatment and cleaning methods for sediment filters and membrane filters, with the goal of extending the lifespan of used filters. Further, the study suggested future study directions on the recycling of used water purifier filters, which could be useful information on establishing environmental policy to promote the recycling of used filters.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.248-251
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• 1990

A new CAD program for double E-plane bandpass filters is developed based on the variational analysis method and the passband correction method combined with the synthesis procedures. By taking the widths of three narrow waveguide equally, we can design bandpass filters with best stopband characteristics.