• Journal of the Korean Graphic Arts Communication Society
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• v.16 no.3
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• pp.121-131
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• 1998

The object color does not look same under the different light source. It depends on the surface spectral reflectance and the spectral distribution of light source. Therefore we should find the surface spectral reflectance of object color and the spectral distribution of light source for color reproduction. Using Wiener estimation, we can estimate the spectral reflectance from low dimensional images obtained with multi-band image acquisition system. The kind and the number of imaging filters have the effect on the estimation of the spectral reflectance. Therefore it is important that optimal filters are selected to minimize the error of the result. In this paper, we describe methods to select optimal filters with minimum error between measured and estimated surface spectral reflectance and to estimate surface spectral reflectance of Munsell color chart from six multi-band images by using Wiener estimation.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.850-853
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• 1987

A VLSI digital filter design using a semi-custom method is described. The digital filters composed of TDM/FDM Transmultiplexer are designed. Using the polyphase network approach a filter bank composed of only all-pass digital filter sections was designed. The use of all-pass filters as basic building blocks is shown to provide a transmultiplexer structure that has low computational requirements, low quantization noise, and high modularity. The silicon compiler systems is used to reduce the design time and increase the credibility of designed filters. A design of 1st order and 2nd order all pass filters is done using CMOS 2um N-well double metal cell.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.304-306
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• 2005

This paper presents the RTDS training course on using passive filters for control of harmonic currents. The course can show harmonic currents in porer system, which is occurred by function generators, with Fourier analysis function of RTDS and the effect of passive filters implemented in RTDS to eliminate harmonics. In addition to, With Jeju-Haenam HVDC system, we have simulated the effect of passive filters on harmonic currents occurred by massive power conversion system of HVDC.

• Journal of the Optical Society of Korea
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• v.20 no.2
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• pp.263-268
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• 2016

Broadband metal-dielectric-metal terahertz filters composed of complementary rings are designed and demonstrated. Four samples with different parameters were fabricated. Results measured using THz time-domain spectroscopy system show excellent agreement with simulations. Compared with the broadband filters reported before, the complementary ring structure in our design is insensitive to any polarization at normal incidence due to symmetry of the ring. Furthermore, the influence of structure parameters (such as period, radius, slot width, thickness and incidence angles) on the transmission characteristics has been investigated theoretically. The encouraging results afforded by designing of the filters could find applications in broadband sensors, terahertz communication systems, and other emerging terahertz technologies.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.1
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• pp.33-38
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• 1994

In this paper, waveguide banpass filters using H-plane step discontinuities are designed based on the field theory analysis and optimization of the resonator lengths as well as dimensions of discontinuities, instead of the conventional synthesis method based on the equivalent circuit. The waveguide inductive obstacles introduced by H-plane step discontinuities analyzed using mode-matching method and the generalized scattering parameters are derived. Using the derived scattering parameters of the discontinuities as well as those of resonators, waveguide bandpass filters are designed through optimization method, modified Razor search method proposed by J.H.Bandler. Using this design procedures, waveguide bandpass filters are designed and tested at X-band(center frequency 10GHz) as well as Ka-band(center frequency 35GHz).

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.5
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• pp.42-49
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• 1994

In this paper we consider efficient 1-D and 2-D linear-phased half-band filter designs. We first introduce a new derivation of the existing Vaidynathan-Nguyen 's half-band filter design method, which verifies that the design provides optimal half-band filters. We then propose an approximately-linear-phased IIR half-band filter design method, which is based on the all-pass equalizer design with the linear phase -$\omega$/2. Finally, we propose an efficient method to design optimal 2-D half-band filters, for which we utilize a 2-D all pass prototype filter of half the order of the desired 2-D half-band filters.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.895-896
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• 2008

We propose a adaptive combination of affine projection algorithm (APA) filters with different update interval. Two APA filters with different update interval are adapted independently in order to keep the advantages of both component filters. This novel scheme provides improvement of performance in term of the convergence rate and the steady-state error. Experimental results show good properties of the proposed algorithm.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.3
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• pp.10-21
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• 1993

Bilinear models are attractive for adaptive filtering applications because they can approximate a large class of nonlinear systems adequately, and usually with considerable parsimony in the number of coefficients compared with Volterra models. But bilinear filters have stability problem because they involve nonlinear feedback. Adaptive algorithms for bilinear filters may be diverge and have poor convergence characteristics when input signal is large In this paper, necessary and sufficient condition for mean square stability of bilinear filters for given input signal statistics is briefly described, and the method obtaining the input bound to guarantee the stability of bilinear filters is presented. New RPEM algorithm, which does not diverge and has the superior convergence characteristics compared with the conventional RPEM algorithm when input signal is large, is derived by applying the time-varying Kalman filtering concept to the conventional RPEM algorithm.

• The Pure and Applied Mathematics
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• v.19 no.2
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• pp.127-136
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• 2012

In this paper, we introduce the notion of an implicative vague filter in BE-algebras, and investigate some properties of them. Also we give conditions for a vague set to be an implicative vague filter, and we characterize implicative vague filters in BE-algebras. We define the notion of $n$-fold implicative vague filters in BE-algebras and we give characterizations of $n$-fold implicative vague filters and $n$-fold implicative BE-algebras.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.5
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• pp.33-40
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• 1998

In this paper, a design of current-mode continuous-time filters for low voltage and low frequency applications using complementary bipolar current mirrors is presented. The proposed current-mode filters consist of simple bipolar current mirrors and capacitors and are quite suitable for monolithic integration. Since the design method of the proposed current-mode filters are based on the integrator type of realization, it can be used for a wide range of applications. Since the input impedance of simple bipolar current mirror is small, in this paper, negative feedback amplifier is used to realize is designed by cascade method. The cutoff frequency of the designed filter can be easily tunable by the DC controlling current from 60kHz to 120kHz. The characteristics of the designed current-mode filters are simulated and examined by SPICE using standard bipolar transistor parameters.