• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.10 no.4
• /
• pp.269-274
• /
• 2010

After introducing many different types of prefilter convergence, we introduce an universal method to define various notions of compactness using cluster point and convergence of a prefilter and to prove the Tychonoff theorem using characterizations of ultra(maximal) prefilters.

• Korean Journal of Mathematics
• /
• v.10 no.1
• /
• pp.5-10
• /
• 2002

In this paper, we investigate the prefilter base on a fuzzy set and fuzzy net ${\varphi}$ on the fuzzy topological space (X,${\delta}$). And we show that the prefilter base $\mathcal{B}({\varphi})$ determines by the fuzzy net ${\varphi}$ converge to a fuzzy point $p$ iff the fuzzy net ${\varphi}$ converge to a fuzzy point $p$. Also we prove that if the prefilter base $\mathcal{B}$ converge to a fuzzy point $p$, then the $\mathcal{B}$ has the cluster point $p$.

• Korean Journal of Mathematics
• /
• v.4 no.2
• /
• pp.173-178
• /
• 1996

In this paper, we discuss quasi-fuzzy H-closed space and introduce ${\theta}$-convergence of prefilter in fuzzy topological space. And we define ${\theta}$-closed fuzzy set using by ${\theta}$-convergence.

• Journal of the Institute of Electronics Engineers of Korea TE
• /
• v.39 no.4
• /
• pp.370-378
• /
• 2002

Fuzzy inference which combines numerical data and linguistic data has been used to design adaptive filter algorithms. In adaptive IIR filter design, the fuzzy prefilter is taken account, and applied to both direct and lattice structure. As for the fuzzy inference of the fuzzy filter, the Sugeno's method is employed. As membership functions and inference rules are recursively generated through neural network, the accuracy can be improved. The proposed adaptive algorithm, adaptive IIR filter with fuzzy prefilter, has been applied to adaptive system identification for the purposed of performance test. The evaluations have been carried out with viewpoints of convergence property and tracking properties of the parameter estimation. As a result, the faster convergence and the better coefficients tracking performance than those of the conventional algorithm are shown in case of direct structures.

• Proceedings of the KIEE Conference
• /
• 1995.07b
• /
• pp.471-475
• /
• 1995

This paper deals with the aliasing problem minimized by using an analog low-pass prefilter have a sampling frequency of 18000 Hz is designed and describes to extract their fundamental frequency components by AFT filter. And them distance relaying algorithm based AFT filter is computational simple, good frequency response and fast convergence in calculation of system apparant impedance. We performed off-line simulation using data from EMTP.