• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3647-3653
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• 2012

In active noise control filter, IIR filter structure which used for control filter assures the stability property. The stability characteristics of IIR filter structure is mainly determined by pole location of control filter within unit disc, so stable selection of the value of control filter coefficient is very important. In this paper, we proposed novel adaptive stabilized Filtered_U LMS algorithms with IIR filter structure which has better convergence speed and less computational burden than conventional FIR structures, for multi-channel active noise control with vehicle enclosure signal case. For better convergence speed in adaptive algorithms, fuzzy LMS algorithms where convergence coefficient computed by a fuzzy PI type controller was proposed.

• Journal of the Korean Solar Energy Society
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• v.39 no.2
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• pp.81-92
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• 2019

When Photovoltaic inverter is connected to grid and used as PVPCS (Photovoltaic Power Conditioning System), 120 Hz AC ripple occurs at the dc-link capacitor voltage. This AC ripple reduces the efficiency of PVPCS and shortens the lifetime of the capacitor. In this paper, we design a notch filter to remove AC ripple. As a result, the AC voltage ripple was removed from the dc link and the THD of the PVPCS output current with the notch filter was lowered. This notch filter is determined by the damping coefficient, the bandwidth coefficient, and the switching frequency. Among these, the switching frequency determines the switching loss and the size of the LC filter, and the PVPCS with the high switching frequency has a greater efficiency loss due to the switching loss than the efficiency improvement by the notch filter. Therefore, it is important to set the optimum switching frequency in the PVPCS with the notch filter applied. In this paper, THD and switching loss of PVPCS output current with notch filter are calculated through simulation, and cost function to calculate optimum switching frequency through data is proposed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.11
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• pp.84-90
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• 2010

In this paper, the reduced size of broad bandpass filter with parallel coupled line structure is presented. This proposed filter can control bandwidth of narrow to broadband by adjusting the coupling coefficient. The conventional filter is operated with a narrow band. If a higher bandwidth is desired than the conventional narrow bandwidth, it is hard to realize due to the coupling coefficient between feeding line and resonator. In this paper, to overcome this limitation, a proposed bandpass filter is designed with reduced size due to SIR(Stepped Impedance Resonator) and multi-grade type structures than conventional one, and it has characteristics of adjusting bandwidth freely as per quantity of coupling coefficient. The proposed bandpass filter that, experimental results of insertion and return losses are 0.42 dB and 20.9 dB with bandwidth of 60 % at the center frequency of 5.8 GHz, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.407-413
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• 2011

In this paper, the reduced size of broad bandpass filter with parallel coupled line structure is presented. This proposed filter can control bandwidth of narrow to broadband by adjusting the coupling coefficient. The conventional filter is operated with a narrow band. If a higher bandwidth is desired than the conventional narrow bandwidth, it is hard to realize due to the coupling coefficient between feeding line and resonator. In this paper, to overcome this limitation, a proposed bandpass filter is designed with reduced size due to SIR (Stepped Impedance Resonator), U-shaped open stub with hair-pin and vertical-type structure than conventional one, and it has characteristics of adjusting bandwidth freely as per quantity of coupling coefficient. The proposed bandpass filter that, experimental results of insertion and return losses are 0.42 dB and 24.5 dB with bandwidth of 60 % at the center frequency of 5.8 GHz, respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.84-90
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• 2011

In active noise control filter, LMS algorithms which used for control filter, assure the convergence property, and computational burden of these algorithms are proportionate to the filter taps. The convergence speed of LMS algorithms is mainly determined by value of the convergence coefficient, so optimal selection of the value of convergence coefficient is very important. In this paper, We proposed novel adaptive fuzzy logic LMS algorithms with FIR filter structure which has better convergence speed and less computational burden than conventional LMS algorithms, for single channel active noise control with ill conditioned signal case. Computer simulations were performed to show the effectiveness of a proposed algorithms.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1319-1324
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• 2007

A tank model in conjunction with Kalman filter is developed for prediction of sediment yield from an upland watershed in Northwestern Mississippi. The state vector of the system model represents the parameters of the tank model. The initial values of the state vector were estimated by trial and error. The sediment yield of each tank is computed by multiplying the total sediment yield by the sediment yield coefficient. The sediment concentration of the first tank is computed from its storage and the sediment concentration distribution(SCD); the sediment concentration of the next lower tank is obtained by its storage and the sediment infiltration of the upper tank; and so on. The sediment yield computed by the tank model using Kalman filter was in good agreement with the observed sediment yield and was more accurate than the sediment yield computed by the tank model.

• Journal of the Korean Ceramic Society
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• v.43 no.6 s.289
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• pp.351-357
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• 2006

The fabrication process of the honeycomb filter was investigated using synthesized cordierite with the addition of pore former and extrusion additives (either organic matter or graphite). Also, the effect of additives on the resultant properties of honeycomb filter such as porosity, thermal expansion coefficient and mechanical strength were investigated. With increasing the organic matter up to 10 wt%, porosity was increased but compressive strength was decreased. With increasing the graphite content, however, both porosity and compressive strength were increased. The specimen with an optimum processing condition (C-17A30G, sintering at $1150^{\circ}C$) was demonstrated 59% in porosity, 69 MPa in compressive strength, and $2.4{\times}10^{-6}/^{\circ}C\;(25{\sim}1000^{\circ}C$) in thermal expansion coefficient, which physical properties are appropriate for the honeycomb filter applications.

• Proceedings of the KSRS Conference
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• 2007.03a
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• pp.183-187
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• 2007

적조원격탐사의 기초연구로서 적조생물의 광학적 특성을 조사하였다. 연구에 사용된 적조생물 종은 와편모조류에 속하는 종으로 Scrippsiella trochoidea이다. 광학적 특성 조사를 위해 순수 배양된 생물종을 미세조류은행(KMCC)에서 구입하여 배양하였다. 배양된 샘플로 chlorophyll 농도, 홉광계수(absorption coefficient, a), 소산계수 (attenuation coefficient, c), 역산란계수(backscattering coefficient, $b_b$), 입자크기분포(size distribution, Fd)를 측정하였다. 본 연구의 결과는 2000년 적조 생물종 원격탐사 기술개발 보고서의 결과와 비교해 보았으며, 홉광계수 측정방법에 있어서 filter technique과 부유상태에서 측정한 결과를 비교하였다. 홉광계수에 있어서 기존연구와 본연구의 결과는 매우 유사한 홉광 스펙트럼올 나타내었으며，filter technique와 부유상태에서 측정한 홉광도는 filter technique를 이용한 것이 높은 값을 나타내었다. 이는 multiple absorption, 즉 ${\beta}-effect$에의한 것으로 보인다. 역산란 스펙트럼은 노이즈가 많이 나타났는데 이것은 농도가 충분하지 않아서 나타난 것으로 추정된다. 적조생물의 고유광특성이 해색에 영향을 미칠것이라고 보고 이들 결과는 해색을 재현하기 위한 해색모텔의 입력변수로 활용될 수 있다.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.E2
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• pp.49-56
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• 2005

A long-path transmissometer is one of the optical instruments widely used to measure atmospheric light extinction coefficient without enclosing a light beam and perturbing aerosols. Over the past two decades, a number of measurements have been carried out using the long-path transmissometer manufactured by OPTEC, Inc. Calibration of the transmissometer should be performed when any component of the transmissometer system is interchanged or installation condition is changed. For a better calibration of the transmissometer, application of a modified calibration method for the existing neutral density (ND)-filter method was recommended for the computation of the atmospheric transmittance using model MODTRAN 4 in this study. It was revealed that the measured light extinction coefficient from the transmissometer which was calibrated using the existing ND-filter method could be overestimated due to the assumption of the atmospheric transmittance suggested by OPTEC, Inc. The uncertainty of the measured light extinction coefficient from the transmissometer calibrated based on the modified ND-filter method was calculated to be approximately $13Mm^{-1}$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.379-385
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• 2015

This paper proposes the hardware architecture of high performance ALF(Adaptive Loop Filter) for efficient filter coefficient estimation. In order to make the original image which has high resolution and high quality into highly compressed image effectively and also, subjective image quality into improved image, the ALF technique of HEVC performs a filtering by estimating filter coefficients using statistical characteristics of image. The proposed ALF hardware architecture is designed with a 2-step pipelined architecture for a reduction in performance cycle by analysing an operation relationship of Cholesky decomposition for the filter coefficient estimation. Also, in the operation process of the Cholesky decomposition, a square root operation is designed to reduce logic area, computation time and computation complexity by using the multiplexer, subtracter and comparator. The proposed hardware architecture is designed using Xilinx ISE 14.3 Vertex-7 XC7VCX485T FPGA device and can support 4K UHD@40fps in real time at a maximum operation frequency of 186MHz.