• Title/Summary/Keyword: filter performance

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A Robustness Improvement of Adjoint-LMS Algorithms for Active Noise Control (능동소음제어를 위한 Adjoint-LMS 알고리즘의 강인성 개선)

  • Moon, Hak-ryong;Shon, Jin-geun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.65 no.3
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    • pp.171-177
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    • 2016
  • Noise problem that occurs in living environment is a big trouble in the economic, social and environmental aspects. In this paper, the filtered-X LMS algorithms, the adjoint LMS algorithms, and the robust adjoint LMS algorithms will be introduced for applications in active noise control(ANC). The filtered-X LMS algorithms is currently the most popular method for adapting a filter when the filter exits a transfer function in the error path. The adjoint LMS algorithms, that prefilter the error signals instead of divided reference signals in frequency band, is also used for adaptive filter algorithms to reduce the computational burden of multi-channel ANC systems such as the 3D space. To improve performance of the adjoint LMS ANC system, an off-line measured transfer function is connected parallel to the LMS filter. This parallel-fixed filter acts as a noise controller only when the LMS filter is abnormal condition. The superior performance of the proposed system was compared through simulation with the adjoint LMS ANC system when the adaptive filter is in normal and abnormal condition.

Development and Performance Evaluation of Positively Charged Porous Filter media for Water Purification System (정수 설비를 위한 양전하가 부가된 다공성 수처리 필터 개발과 성능평가)

  • Lee, Chang-Gun;Joo, Ho-Young;Lee, Jae-Keun;Ahn, Young-Chull;Park, Seong-En
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.95-98
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    • 2006
  • Filtration by fibrous filter is one of the Principle methods used for removing pollutant particles in the liquid. Because of the increasing need to protect both human health and valuable devices from exposure to fine particles, filtration has become more important. Filters have been developed with modified surface charge characteristics to capture and adsorb particles by electrokinetic interaction between the filter surface and particles contained in water. The main purposes of this study are to develop and evaluate the performance evaluation of the apparatus for making a positively charged porous filter media and to analyze the surface characteristics of the filter media for capturing negavitely charged contaminants mainly bacteria and virus from water. The experimental apparatus consists of a mixing tank, a vacuum pumping system, a injection nozzle, a roller press and a controller. The filter media is composed of glass fiber(50-750 nm), cellulose($10-20{\mu}m$) and colloidal charge modifier. The characteristics of filter media is analyzed by SEM(Scanning Electron Microscopy), AFM(Atomic Force Microscopy) and quantified by measuring the zeta potential values.

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Effect of the Internal Shape of eDNA Filter Case made by the PBF method Metal 3D Printer on Water Sampling Performance (PBF 방식 금속 3D프린터로 제작된 환경DNA 필터 케이스의 내부 형상이 포집 성능에 미치는 영향)

  • Lee, Seung-Min;Park, Se-Hyun;Kwak, Ihn-Sil;Kim, Hyoung-Ho;Kwak, Tae-Soo
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.8
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    • pp.74-79
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    • 2021
  • This study focuses on designing a filter case using a water pump for application in eDNA filtering systems. Filter cases, channel type and net type were designed based on the flow field and made using a 3D printer for metal. Flow analysis was conducted for each filter case, and the results were consistent with the pressure experiment results. Furthermore, the water sampling performance test showed that the channel-type filter case exhibited a high flow rate and low pressure through the filter. The eDNA extraction experiment showed that the channel type exhibited improved capture ability compared to the net type.

Performance assessment of HEPA filter to reduce internal dose against radioactive aerosol in nuclear decommissioning

  • Hee Kwon Ku;Min-Ho Lee;Hyunjin Boo;Geun-Dong Song;Deokhee Lee;Kaphyun Yoo;Byung Gi Park
    • Nuclear Engineering and Technology
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    • v.55 no.5
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    • pp.1830-1837
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    • 2023
  • The thermal cutting of contaminated or activated metals during decommissioning nuclear power plants inevitably results in the release of radioactive aerosol. Since radioactive aerosols are pernicious particles that contribute to the internal dose of workers, air conditioning units with a HEPA filter are used to remove radioactive aerosols. However, a HEPA filter cannot be used permanently. This study evaluates the efficiency and lifetime of filters in actual metal cutting condition using a plasma arc cutter and a high-resolution aerosol detector. The number concentration and size distribution of aerosols from 6 nm to 10 ㎛ were measured on both the upstream and downstream sides of the filter. The total aerosol removal efficiency of HEPA filter satisfies the standard of removing at least 99.97% of 0.3 ㎛ airborne particles, even if the pressure drop increases due to dust feeding load. The pressure drop and particle size removal efficiency at 0.3 ㎛ of the HEPA filter were found to increase with repeated cutting experiments. By contrast, the efficiency of used HEPA filter reduced in removing nano-sized aerosols by up to 79.26%. Altogether, these results can be used to determine the performance guidance and replacement frequency of HEPA filters used in nuclear power plants.

Implementation of adaptive filters using fast hadamard transform (고속하다마드 변환을 이용한 적응 필터의 구현)

  • 곽대연;박진배;윤태성
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.1379-1382
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    • 1997
  • We introduce a fast implementation of the adaptive transversal filter which uses least-mean-square(LMS) algorithm. The fast Hadamard transform(FHT) is used for the implementation of the filter. By using the proposed filter we can get the significant time reduction in computatioin over the conventional time domain LMS filter at the cost of a little performance. By computer simulation, we show the comparison of the propsed Hadamard-domain filter and the time domain filter in the view of multiplication time, mean-square error and robustness for noise.

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A New Master-Slave Filter-Bank with Series-Parallel Structure for Tracking Center Frequency (주파수 추적을 위한 직병렬 구조의 새로운 주종 필터뱅크)

  • 윤형식;임재환;이석필;박상희
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.43 no.2
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    • pp.339-345
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    • 1994
  • A new filter-bank is proposed in order to track center frequency of narrow band signal. The two banks are connected in series-parallel. The master filter bank which is made of traditional filter bank detects the center frequency roughly. And the performance for tracking center frequency is greatly improved by the slave filter bank which is based on energy-difference estimator. Computer simulations show that it achieves a good tracking accuracy.

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A Study on the Algorithm for Adaptive Odd/Even Multi-shell Median Filter (가변 문턱조건을 이용한 odd/even median filter 알고리즘)

  • 조상복;이일권
    • Proceedings of the IEEK Conference
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    • 1999.11a
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    • pp.495-498
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    • 1999
  • In this paper, we propose the adaptive Odd/Even Multi-shell Median Filter(adaptive O/E MMF) to improve the defect that Modified Multi-shell Median Filter(MMMF) can not recover missing lines of vertical and cross direction. This filter uses odd/even multi-shells and new proposed threshold strategy The performance of the proposed filter is evaluated over image 'airfield 'by using MATLAB. As the proposed threshold strategy eliminate the number of redundant replacement, it suppresses impulse noise and recovers missing lines.

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Fuzzy $\alpha-\beta$ filter for vehicle tracking (차량 추적 성능 향상을 위한 퍼지 $\alpha-\beta$ 필터)

  • 정태진;김인택;한승수
    • Proceedings of the IEEK Conference
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    • 2000.06e
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    • pp.43-46
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    • 2000
  • In this paper, we present a method for vehicle tracking systems using $\alpha$-$\beta$ filter based on fuzzy logic. The $\alpha$-$\beta$ filter estimates the future target positions using fixed $\alpha$.$\beta$ coefficients. We utilize the fuzzy logic to make $\alpha$ and $\beta$ coefficients very with the position. Comparisons of tracking performance made for three different schemes: the $\alpha$-$\beta$ filter, $\alpha$-$\beta$filter using fuzzy logic, and the kalman filter.

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Treatment of the Herniated Nucleus Pulposus Syndrome by Chemonucleolysis with Chymopapain

  • Dabezies, Eugene J.
    • Journal of Biomedical Engineering Research
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    • v.5 no.2
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    • pp.111-120
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    • 1984
  • A new restoration method of chest X-ray image (dual project filter) was proposed to improve SNR (signal to noise ratio) characteristics. In this method, a priori information of system and anatomical structure and statistics of projected object are used in the design of filter. Dual projection filter varies its parameters, adapting to the local regions of chest(lungregion, mediasternum, subdiaphragm) and the structure of chest (bone, tissue, blood vessel, bronchia). The performance of Dual Projection Filter was 0.1-0.2dB better than Dual Sensor Wiener Filter, which was used for initial estimate of Dual Porjection Filter.

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A Study on Lip-reading enhancement using RATSTA fileter (RASTA 필터를 이용한 립리딩 성능향상에 관한 연구)

  • Shin Dosung;Kim Jinyoung;Choi Seungho;Kim Sanghun
    • Proceedings of the KSPS conference
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    • 2002.11a
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    • pp.191-194
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    • 2002
  • Lip-reading technology that is studied them is used to compensate speech recognition degradation in noise environment in bi-modal's form. The most important thing is that search for correct lips area in this lip-reading. But, it is hard to forecast stable performance in dynamic environment. Used RASTA filter that show good performance to remove noise in the speech to compensate. This filter shows that improve performance of using time domain of digital filter. To this experiment observes performance of speech recognition only using image information, service chooses possible 22 words and did recognition experiment in car. We used hidden Markov model by speech recognition algorithm to compare this words' recognition performance.

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