• Title/Summary/Keyword: 고주파통과필터

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A Visual Quality Enhancement of Medical Image Using Optimized High-Frequency Emphasis Filter (고주파 강조필터를 이용한 의료영상의 화질향상을 위한 최적화 방법)

  • Shin, Choong-Ho;Jung, Chai-Yeoung
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.7
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    • pp.1681-1685
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    • 2014
  • The visual quality of medical image is an important factor for diagnosis accuracy. Therefore, the methods to improve the quality of medical image have studied. Among them, frequency domain filter is very powerful method to impove the visual quality of image. In this paper, the X-ray medical image using optimized high-pass filter was improved edges. The result image was improved edge and contrast of flat area using optimized high frequency emphasis filter. At last, the result image is to minimize the noise using the minimum mean square error(MMSE) filter. As a result, the proposed method has enhanced contrast and edge of the image in the contrast of existing filters, with the noise canceling effect.

Design and Implementation of LNA and BPF for RF System in Digital TRS Base Station (I) ; Receiving Part (디지털 TRS 기지국의 RF 시스템 수신부를 위한 저잡음증폭기와 대역통과필터의 설계 및 제작)

  • 구인모;이상설
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.10 no.6
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    • pp.900-909
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    • 1999
  • The receiving part of the RF system for the digital TRS base stations is developed in this paper. Based on the system specifications, the structure of the RF system is accomplished and its block diagram is drawn. The RF system is implemented according to these block diagrams. Subsequently the RF band-pass filter, the low noise amplifier, the automatic level controlled attenuator, the frequency synthesizer and other components for the system are designed and implemented, and a main board to integrate these modules is also manufactured. To lower the noise floor of the system and suppress the RF spurious noise, a PCB layout is performed carefully. For each module consisting of the RF system and the entire system, the performance tests are accomplished to check the specifications.

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Sound Synthesis of Piri by Asymmetric Frequency Modulation (비대칭 FM합성방식을 이용한 피리 소리의 합성)

  • Pyoun, Joong-Bae;Cho, Sang-Jin;Chong, Ui-Pil
    • Proceedings of the Korea Institute of Convergence Signal Processing
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    • 2006.06a
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    • pp.37-40
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    • 2006
  • FM(Frequency Modulation) 음 합성방식은 오랫동안 연구되어 왔고 여러 가지 효과를 주기에 유용하고 비교적 낮은 사양으로 높은 수준의 배음을 합성할 수 있지만 그 응용분야가 대부분이 서양악기 위주의 연구였다. 이에 본 논문에서는 국악 관악기인 피리를 주파수 영역에서 저주파 영역과 고주파 영역으로 나누어 분석하고 이 결과를 이용하여 FM 파라미터를 추출하고 비대칭 FM합성방식으로 1차적인 소리를 합성하였다. 분석된 저주파 영역과 고주파 영역의 특성을 각각의 역 필터링을 위한 2개의 필터를 설계하여 이를 다시 합성된 소리를 통과시켜 두 소리를 합산함으로써 더욱 원음과 유사한 소리를 합성할 수 있었다.

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Characteristics of High Efficiency Wideband Microstrip Band Pass Filter (고효율 광대역 마이크로스트립 대역통과필터 특성)

  • Lee, Young-Hun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.4
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    • pp.636-644
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    • 2009
  • This paper presents a compact, low insertion loss, sharp rejection and wide band microstrip band pass filter that is composed rectangular loop resonator and step-impedance-open-stub(SIOS) for wireless data communication. The SIOS can be reduce length about 30% more than general $0.25{\lambda}$ stub. And the stub can the advantage of tuning impedance magnitude. In order to demonstrate agrement of this paper prove, the optimized wide band pass filters are realized and experimented. A transmission line model used to calculate the frequency response of the new filters shows good agreement with measurements. The filter has 3dB fractional bandwith of 52.5%(3.267GHz), an insertion loss of better than 0.33dB from 4.587GHz to 7.854GHz, and two rejection of greater than 30dB within 221MHz$(4.366GHz{\sim}4.587GHz)$ at low frequency band, 181MHz$(7.854GHz{\sim}8.035GHz)$ at high frequency band. Maximum rejection characteristics of the filter are -54dB at low frequency and -60dB at high frequency.

A Dual-Mode Canonical Filter with Dual-Passband for Satellite Transponder (두 개의 통과대역을 갖는 위성 중계기용 이중모드 정규(Canonical) 구조 필터)

  • 이주섭;엄만석;염인복;박종흥
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.3
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    • pp.278-283
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    • 2004
  • Due to the complex arrangement of frequency plans and spatial overages in modern satellite communications, channels that are non-contiguous in frequency may be amplified by a single power amplifier and transmitted to the ground through one beam. In this paper, a dual-mode canonical filter with dual-passband is presented. The filter adopts dual-mode technique for mass and volume reduction. Canonical structure is adopted for maximum transmission zero realization. To validate the design technique, a 6-pole dual-mode canonical dual-passband filter for Ka-band(30/20 ㎓) satellite transponder is realized. The measured frequency response of the filter shows good agreement with the computed one.

Design of Lowpass Filter With the Wide Stopband Characteristics Using Microstrip Line (마이크로스트립 선로를 이용한 광대역 차단특성을 가지는 저역통과 필터 설계)

  • Choi Dong-Muk;Shim Joon-Hwan;Jeon Joongn-Sung;Kim Dong-Il
    • Journal of Navigation and Port Research
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    • v.30 no.5 s.111
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    • pp.331-334
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    • 2006
  • In this paper, we designed and fabricated the lowpass filter with the wide stopband characteristics using microp- strip line. Adding the $\lambda_g/4$ open stub at the input and output ports, we developed the L-C ladder type lowpass filter using the open stub which has wide stopband characteristics. In order to reduce the entire size qf this filter, the high impedance microstrip lines were made with the meander structure. The lowpass filter was fabricated with the cutoff frequency 2.3 GHz and its measured frequency responses agree well with the simulation results.

Bandpass Filter Based Focus Measure for Extended Depth of Field (피사계심도 확장을 위한 대역통과 필터 기반 초점 정량화 기법)

  • Cha, Su-Ram;Kim, Jeong-Tae
    • Journal of Broadcast Engineering
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    • v.16 no.5
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    • pp.883-893
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    • 2011
  • In this paper, we propose a novel focus measure that determines in-focus and out-of-focus region in an image. In addition, we achieved extended depth of field by blending the acquired image and Wiener filtered image using a decision map based on the designed focus measure. Since conventional focus measures are based on the amount of high frequency components in an acquired image, the measures may not be accurate if there exist high frequency components in out-of-focused region. To overcome the problem, we designed the novel focus measure based on effective band pass filtering. In simulations and experiments, the proposed method showed better performance than existing methods.

Characteristics for High Efficiency and Wideband Band Pass Filter Using Rectangular Resonator and Step-Impedance-Open-Stubs (구형 공진기와 계단 임피던스 개방 스터브를 사용한 고효율 광대역 대역 통과 필터 특성)

  • Lee, Young-Hun;Kwon, Won-Hyun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.2
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    • pp.200-207
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    • 2009
  • This paper presents a compact, low insertion loss, sharp rejection and wide band microstrip band pass filter that is composed rectangular loop resonator and Step-Impedance-Open-Stub(SIOS). The SIOS can be reduce length about 30 % more than general 0.25 $\lambda$ open stub. And the stub can the advantage of tuning impedance magnitude. In order to demonstrate agrement of this paper prove, the optimized wide band pass filters are realized and experimented. A transmission line model used to calculate the frequency response of the new filters shows good agreement with measurements. The filter has 3 dB fractional bandwidth of 51.75 %(3.206 GHz), an insertion loss of better than 0.44 dB from 4.587 GHz to 7.793 GHz, and two rejection of greater than 30 dB within 221 MHz($4.326{\sim}4.587\;GHz$) at low frequency band, 181 MHz($7.739{\sim}7.954\;GHz$) at high frequency band. Maximum rejection characteristics of the filter are -61.8 dB at low frequency and -76.3 dB at high frequency.

The Bandpass Filter with Transmission Zero Using . the Effect of Effective Inductance and Multi-layer PCB (유효 인덕턴스 효과와 적층 PCB를 이용한 하나의 전송 영점을 갖는 대역 통과 필터)

  • Kim, Yu-Seon;Nam, Hun;Lee, Geon-Cheon;Seo, In-Jong;Lim, Yeong-Seog
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.11 s.114
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    • pp.1089-1095
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    • 2006
  • In this paper, the circuit analysis of three-dimensional bandpass filter with transmission zero in multi-layer printed circuit board is presented. The equivalent circuit of bandpass filter is evaluated by microwave network analysis. Compare to the established paper that have configured the circuit model of filter except the effect of distribute element, the proposed model can include the effect. As a result, the multi-layer PCB bandpass filter with transmission zero has designed by extracting mutual capacitance from electrical component inside inductor. The structure size is only $10mm{\times}20mm{\times}1.251mm$. Measured data of the bandpass filter indicate 1.9 dB of insertion loss and 28 dB of return loss at the center frequency of 1.84 GHz, as well as 43 dB attenuation at the refraction frequency of 2.78 GHz.

Detection Method of Series Arc Signal (직렬아크신호지 검출방법)

  • Kil, Gyung-Suk;Ji, Hong-Keun;Park, Dae-Won;Kim, Il-Kwon;Rhyu, Keel-Soo;Song, Jae-Yong
    • Journal of the Korean Society for Railway
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    • v.11 no.5
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    • pp.477-481
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    • 2008
  • This paper dealt with a detection method of series arc existence which is a symptom of electric fires in low-voltage system. The proposed detection circuit consists of a high-pass filter with a low cut-off frequency of 3kHz to attenuate power frequency voltage by 80 dB and an active band-pass filter with a center frequency of 4kHz to detect only the series arc signals. The performance of the circuit was evaluated in a phase-controlled incandescent lamp as a non-linear load and an inverted-fed induction motor as a high frequency load by using the arc generator specified in UL1699. From the experimental results, it was confirmed that the proposed method solved the detection error, which is being the most problem, by discriminating the series arc signal even in non-linear and high frequency loads.