• Nuclear Engineering and Technology
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• 제39권6호
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• pp.725-730
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• 2007

This paper describes recently developed techniques for effective filtering of neutron detector signal noise. In this paper, three kinds of noise filters are proposed and their performance is demonstrated for the estimation of reactivity. The tested filters are based on the unilateral kernel filter, unilateral kernel filter with adaptive bandwidth and bilateral filter to show their effectiveness in edge preservation. Filtering performance is compared with conventional low-pass and wavelet filters. The bilateral filter shows a remarkable improvement compared with unilateral kernel and wavelet filters. The effectiveness and simplicity of the unilateral kernel filter with adaptive bandwidth is also demonstrated by applying it to the reactivity measurement performed during reactor start-up physics tests.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.449-452
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• 2014

We present a multi-tap microwave photonic filter with high selectivity through applying time-to-frequency mapping and optical frequency comb shaping techniques. When arranged in the time-to-frequency mapping stage, by a Fourier transform, the deviation of the optical taps to the target profile is significantly reduced while maintaining the apodization profile, resulting in high sidelobe suppression in the filters. By applying a simple time-to-frequency mapping stage to the conventional optical frequency combs, we demonstrate a substantially enhanced (>10dB) sidelobe suppression, resulting in filter lineshapes exhibiting a significantly high (>40dB) main lobe to sidelobe suppression ratio. These results highlight the potential of the technique for implementation in various passband filters with high sidelobe suppression.

• ETRI Journal
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• 제28권2호
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• pp.223-226
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• 2006

This letter presents a new approach to synthesize the resonator filters of an arbitrary topology. This method employs an optimization method based on the relation between the polynomial coefficients of the transfer function and those of the $S_{21}$ from the coupling matrix. Therefore, this new method can also be applied to self-equalized filters that were not considered in the conventional optimization methods. Two microwave filters, a symmetric 4-pole filter with four transmission zeros (TZs) and an asymmetric 8-pole filter with seven TZs, are synthesized using the present method for validation. Excellent agreement between the response of the transfer function and that of the synthesized $S_{21}$ from the coupling matrix is shown.

• ETRI Journal
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• 제28권5호
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• pp.607-614
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• 2006

This paper presents a new class of microstrip slow-wave open-loop resonator filters with reduced size and improved stopband characteristics. A comprehensive treatment of both ends loaded with triangular and rectangular ends is described, leading to the invention of a microstrip slow-wave open-loop resonator. Two-resonator and four-resonator bandpass filters are designed at the operating frequency of about 2 GHz, and a bandwidth of 60 MHz. The size of the slow-wave open-loop resonator is optimized from the standpoint of the unloaded Q-factor. The filters are not only compact in size due to the slow-wave effect, but also have a wider upper stopband resulting from the dispersion effect. The filter designs of this type are described in details. The experimental results are demonstrated and discussed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.237-240
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• 2000

We have proposed a simple method based on IIR filters for realizing sound image localization. How-ever the nonlinearity of phase characteristics of the IIR filters, which are used for sound image localization, cause decrease of the localization accuracy. In this paper we investigate the influence of phase characteristics on the sound localization. Head-related transfer functions (HRTFs) of a dummy-head are approximated by the IIR filter. We carried out sound image localization experiment with 2-loudspeaker reproduction using the approximated HRTFs. Then the errors which obtained from experiments were compared with the theoretical values which were estimated from the phase shifts of the IIR filters. As a result there was little influence of the nonlinear phase characteristics of the IIR fitters in the localization on the horizontal plane.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.46-49
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• 2000

An iterative deblocking algorithm for DCT-compressed images using two-dimensional FIR filters adapted for local directionality of each block, is proposed. First, we introduce a set of simple lowpass filters, which are adapted for edges of different angles. In conventional deblocking methods based on lowpass-filtering and convex projections, a single filter is applied to a whole image. In the proposed method, on the other hand, a suitable filter is chosen out of the directional filters designed previously in every subimage (typically $8{\times}8$ block). Experimental results indicate that adaptive filtering improves PSNR at each iteration.

• 전자공학회논문지A
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• 제30A권4호
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• pp.1-10
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• 1993

This paper presents the designing/manufacturing scheme of the diplexer for satellite transponder which is composed of 2-channel bandpass filters, coupled with E-plane T-junction, having symmetrical waveguide E-plane step discontinuity structures. The 2-channel bandpass filters of the diplexer are designed by the scheme of connecting ${\lambda}_{g}$/2 shunt stub to the waveguide E-plane, playing the role of heat sinks without attaching a special heat sinks and to give the profitable productivity and allow the low-cost manufacturing at mass production, tuning screws are eliminated which have been used to compensate the operating characteristics of manufactured filters. The 2 channel bandpass filters of manufactured 14/12 GHz diplexer for domestic Ku-band satellite transponder have the return loss of 25 dB, insertion loss of 0.3 dB in passband, and below-50 dB of stopband characteristics (T$_{x}$ : f$_{o}{\pm}$250 MHz, R$_{x}$ : f$_{o}{\pm}$220 MHz) at room temperature.

• 한국통신학회논문지
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• 제15권1호
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• pp.15-20
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• 1990

오랫동안 최소 제곱법에 바탕을 둔 선형 신호복원 방식이 연구되어 널리 쓰여 왔다. 그러나, 선형복원 방식은 실제로 처리해야 할 신호에 적합하지 않을 때가 자주 있다. 이러한 문제점을 풀기 위하여 비선형 신호복원 방식이 제안되었고, 이에 대한 연구가 활발히 진행중이다. 이 논문에서는 신호처리에 자주 쓰이는 여러 비선형 여파기들의 전반적인 성질을 간략히 되살펴 본다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.549-554
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• 2002

Recently, interest in hygiene has been arouse in the health care field. Consequently, Filters with antibacterial agent applied to improve air quality by sterilizing bacteria, fungi, etc. We actually installed antibacterial air filter containing 2.5wt%Ag zeolite on the air intake route to air-conditioner in passenger cu, and evaluated filter's performance on antibacterial effect. By the microbe liquid spattering method, we found that the antibacterial air filter has notably sufficient antibacterial efficiency against standard strains and wild type strains. Antibacterial effect was observed at whole area of filter media by zone of inhibition test. The evaluation of microbe quantity was conducted through mixing dilution plate culture method. In comparison with ordinary filter, the amount of germs attached on antibacterial air filters was larger. The amount of germs attached on ordinary filters was very small since ordinary filters contained less dust. In comparison in antibacterial air filter with thickness, the amount of germs attached on 9mm filter was smaller than that of on 6mm filter. i.e. thicker filter, superior efficiency.

• JSTS:Journal of Semiconductor Technology and Science
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• 제11권1호
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• pp.65-72
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• 2011

In this paper, the T-shape stepped impedance resonators are adopted for the design of microstrip bandpass filters for wide harmonics suppression. The proposed filters are operated at the center frequency of 2.44 GHz and 5.20 GHz, respectively. These bandpass filters have been also applied for a high performance diplexer. The insertion losses at the center frequencies of 2.44 and 5.20 GHz are 1.23 and 1.18, respectively. The applicable return losses for both frequency bands and a wide stopband better than 17 dB up to 20 GHz have been obtained.