• Journal of Korea Multimedia Society
• /
• v.12 no.9
• /
• pp.1210-1216
• /
• 2009

In this paper we analyze the convergence behavior of the recursive least rank (RLR) L-filter. The RLR L-filter is an order statistics filter, filter coefficients of which are the weights according to the order of magnitude of inputs. And RLR L-filter is a non-linear adaptive filter, that uses RLR algorithm for coefficient updating. The RLR algorithm is a non-linear adaptive algorithm based on rank estimates in Robust statistics. The mean and mean-squared convergence behavior of the RLR L-filter is examined with variable step-sizes. The RLR L-filter adapts the median filter type to the heavy-tailed distribution function of impulse noise, and adapts the average filter type to Gaussian noises.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.9 no.1
• /
• pp.59-64
• /
• 2009

In this paper, we study the relations between L-fuzzy topologies and L-filters on a strictly two-sided, commutative quantale lattice L. We define an L-fuzzy neighborhood filter and introduce the notion of L-filter convergence in L-fuzzy topological spaces.

• Journal of Korea Multimedia Society
• /
• v.12 no.1
• /
• pp.26-30
• /
• 2009

We propose an adaptive Recursive Least Rank(RLR) L-filter which uses an L-estimator in order statistics and is based on rank estimate in robust statistics. The proposed RLR L-filter is a non-linear adaptive filter using non-linear adaptive algorithm and adapts itself to optimal filter in the sense of least dispersion measure of errors with non-homogeneous step size. Therefore the filter may be suitable for applications when the transmission channel is nonlinear channels such as Gaussian noise or impulsive noise, or when the signal is non-stationary such as image signal.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.10 no.2
• /
• pp.117-123
• /
• 2005

The cutoff frequency of a LC output filter for Dynamic Voltage Restorers (DVR) limits the control bandwidth of a DVR system while it attenuates the inverter switching ripples. For a selected cutoff frequency of a LC output filter, infinite number of L-C combinations is possible. Although different L-C combination has different filter characteristics, the filter design on L-C combination has been depended on field experiences without clear analysis. This paper proposes a design criterion and design examples for the L-C filter combination considering the control characteristics and the size of DVRs. An experimental DVR system based on the proposed LC output filter design methodology is built and tested.

• Korean Journal of Remote Sensing
• /
• v.28 no.5
• /
• pp.561-571
• /
• 2012

The MTF(Modulation Transfer Function) is one of quality assesment factors to evaluate the performance of satellite images. Image restoration is needed for MTF compensation, but it is an ill-posed problem and doesn't have a certain solution. Lots of filters were suggested to solve this problem, such as Inverse Filter(IF), Pseudo Inverse Filter(PIF) and Wiener Filter(WF). The most commonly used filter is a WF, but it has a limitation on distinguishing signal and noise. The L-curve-based Modified Wiener Filter(MWF) is a solution technique using a Tikhonov regularization method. The L-curve is used for estimating an optimal regularization parameter. The image restoration was performed with Dubaisat-1 images for PIF, WF, and MWF. It is found that the image restored with MWF results in more improved MTF by 20.93% and 10.85% than PIF and WF, respectively.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.5C no.4
• /
• pp.176-179
• /
• 2005

The increasing demand for high density packaging technologies and the evolution to mixed digital and analogue devices has been the con-set of increasing research in thin film multi-layer technologies such as the passive components integration technology. In this paper, Cu and TaO thin film with RF sputtering was deposited for spiral inductor and MOM capacitor on the $SiO_2$/Si(100) substrate. MOM capacitor and spiral inductor were fabricated for L-C band pass filter by sputtering and lift-off. We are analyzed and designed thin films L-C passive components for band pass filter at 900 MHz and 1.8 GHz, important devices for mobile communication system. Based on the high-Q values of passive components, MOM capacitor and spiral inductors for L-C band pass filter, a low insertion loss of L-C passive components can be realized with a minimized chip area. The insertion loss was 3 dB for a 1.8 GHz filter, and 5 dB for a 900 MHz filter. This paper also discusses a analysis and practical design to thin-film L-C band pass filter.

• Proceedings of the KIEE Conference
• /
• 2009.04b
• /
• pp.228-230
• /
• 2009

Nowadays, the LCL-filter type becomes an attractive grid interfacing for grid-connected Voltage Source Inverter (VSI). LCL-filter can render the current harmonics attenuation around the switching frequency by using smaller inductance than L-filter. This paper presents a study about the LCL-filter design for single-phase grid-connected inverter in Photovoltaic (PV) system. According to the expected current ripple, the inductances of the filter can be determined. Based on the absorbed reactive power on capacitor, the capacitance can be calculated. Due to the theoretical analysis, a LCL-filter based single phase grid connected inverter control system are simulated. The studied simulation results are given to validate the theoretical analysis.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.5
• /
• pp.307-314
• /
• 2021

Even though the LCL filters have superior harmonic attenuation ability to L filters, stability has always been an issue. The system could be unstable because of the resonance phenomenon, especially when digital controller is used. Adding a notch filter to the compensator is one approach to solve the problem. Resonance phenomenon can be inhibited by aligning notch frequency to system resonance frequency. However, resonance frequency variation can be obtained because the actual system has a nonstationary characteristic. Therefore, the system could be unstable, where the system parameters are changed when the conventional notch filter is used. An adaptive digital notch filter that stabilizes the system even system parameters are changed. Simulation and experiment results are provided to verify the validity of the proposed adaptive filter.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.1
• /
• pp.104-109
• /
• 2012

In this paper, we propose a way to improve the quality of L-band wireless communication from unfriendly influential factors lying in the neighboring RF bands. The UHF-band system has resonator components and they generate harmonics as the spurious in the L-band. Therefore, a metamaterial CRLH bandpass filter is designed for the purpose of system miniaturization and smaller insertion loss, and its spurious phenomenon is observed in the frequency domain. And its harmonics in the L-band are suppressed by a compact bandstop filter whose equivalent circuit is newly developed. The design methodology is validated by the equivalent circuit to be compared with commercial full-wave EM software simulations, where the spurious is dropped by 20dB. Also, the advantage of the proposed design is presented by the comparison where our filter is much smaller than the conventional parallel edge coupled filter by over 50%, with excellent harmonic suppression.

• Proceedings of the KIEE Conference
• /
• 2004.04a
• /
• pp.118-121
• /
• 2004

The cutoff frequency of a LC output filter for Dynamic Voltage Restorers (DVR) limits the control bandwidth of a DVR system and the attenuation factor against the inverter switching ripples. For a selected cutoff frequency of a LC output filter, infinite number of L-C combinations is possible. Although different L-C combination has different filter characteristics, the filter design on L-C combination has been depended on field experiences without clear analysis. This paper proposes a design criterion and design examples for the L-C filter combination considering the control characteristics and the size of DVRs. An experimental DVR system based on the proposed LC output filter design methodology is built and tested.