• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.673-676
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• 2009

Non-point pollutants, which mainly originate from high traffic roads and rural areas, contaminate the environment by flowing into various rivers and lakes and thus are of interest as an environmental issue. Accordingly, efforts have been made to design and maintain efficient filter systems for the control of the non-point pollutants. Meanwhile, clay-type materials are widely used for the absorption of chemicals included in pollutants and the absorption performances of various clays have been reported in the literature. Thus, the present study proposes a non-destructive monitoring method for the performance of a clay-type filter using electrical resistivity measurement. A series of experimental tests is performed on celite-based particulate filters with infiltrating non-point source pollutants having the same characteristics as pollutants on high traffic roads. Each test measures permeability, resistivity of the filter materials and resistivity of the filtrated water. As the particulate filter materials filtrate pollutants and absorb heavy chemicals (e.g., $Cr^{6+}$, lead, nickel, among others), ionic concentration increases resulting as the electrical resistivity decrease. When the filter systems approach the end of their lifetime, the electrical resistivity of the filter material converges to a very low value due to lowered filter absorption efficiency. Hence, the electrical resistivity of the filtrated water also converges to a low value due to high concentrations of heavy metals. The permeability converges to a very low value because of significantly reduced porosity due to clogging and absorption of pollutants on the filter material. The experimental results show that electrical resistivity monitoring of filter materials is a promising approach to estimation of filter performance and its life expectancy.

• 전력전자학회논문지
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• 제9권6호
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• pp.592-601
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• 2004

능동전력필터의 성능은 인버터의 특성, 제어 방법, 그리고 기준신호발생기의 정확도에 좌우된다. 이중에서 기준신호발생기의 정확도는 능동전력필터의 성능을 결정짓는 가장 중요한 요소이다. 본 논문은 개선된 적응예측필터로 구성한 새로운 기준신호발생기에 대해 소개하고 그 성능을 MATLAB을 이용한 시뮬레이션으로 검증하였다. 그리고 실제 하드웨어의 적용타당성을 평가하기 위해 개선된 기준신호발생기로 구성한 알고리즘을 TMS320C31 DSP(digital signal processor)에 구현하고 이 기준신호발생기를 기반으로 하는 단상능동전력필터의 축소모형을 제작하여 실험을 실시하였다. 시뮬레이션과 실험결과로 제안하는 기준신호발생기가 위상지연이 없는 기준신호를 추출하여 능동전력필터에 활용가능하며 그 성능도 대단히 우수함을 알 수 있었다.

• 한국시뮬레이션학회논문지
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• 제27권3호
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• pp.99-107
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• 2018

본 논문에서는 비선형성을 가지는 측정방정식의 상태값을 효과적으로 추정할 수 있는 확장칼만필터(Extended Kalman Filter/EKF)와 확장칼만필터의 변종들 그리고 코스트 레퍼런스 파티클필터(Cost-Reference Particle Filter/CRPF)를 이용하여 이차원 공간에서 표적추적 성능에 관하여 연구한다. 확장칼만필터의 변종으로 분산점칼만필터(Unscented Kalman Filter/UKF), 중심차분칼만필터(Central Difference Kalman Filter/CDKF), 제곱근 분산점칼만필터(Square Root Unscented Kalman Filter/SR-UKF) 그리고 제곱근 중심차분칼만필터(Square Root Central Difference Kalman Filter/SR-CDKF)를 소개한다. 본 연구에서는 노이즈가 불확실한 표적에 대하여 몬테카를로 시뮬레이션 기법을 이용하여 각 필터들의 평균제곱오차(Mean Square Error/MSE)를 계산하였다. 시뮬레이션 결과 확장칼만필터의 변종들 중에서 제곱근 중심차분칼만필터가 속도와 성능 면에서 가장 우수한 결과를 보여주었다. 코스트 레퍼런스 파티클 필터는 확장칼만필터와 다르게 노이즈의 확률 분포를 알 필요가 없다는 유리한 특성을 가지고 있으며 시뮬레이션 결과 제곱근 중심차분칼만필터보다 처리속도 및 정확도 면에서 우수한 결과를 보여주었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.426-429
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• 1997

This paper proposes a robust H$_{\infty}$ tracking filter to improve the unacceptable target tracking performance for systems with parameter uncertainties. Also, we use here the input estimation approach to account for the possibility of maneuver. Simulation results show that the robust H$_{\infty}$ tracking filter which is proposed here to solve the systems with all system parameter uncertainties, has a good tracking performance for a maneuvering target tracking problem.m.

• 정보통신설비학회논문지
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• 제8권3호
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• pp.107-110
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• 2009

In this paper, a PN code tracking loop with extended Kalman filter (EKF) is proposed for a direct-sequence spread-spectrum. EKF is used to estimate amplitude and delay in a multipath. fading channel. It is shown that tracking error performance is significantly improved by EKF compared with a conventional tracking loop.

• 한국진공학회지
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• 제8권3B호
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• pp.315-321
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• 1999

In this paper, the SEM image processing system based on PC is designed, and a new noise reduction filtering algorithm is proposed. The SEM image obtained in semiconductor processing line is sensitive to noise, the weighted-D filter can remove uniform and Gaussian noise effectively, but can not remove impulse noise properly, A new improved filtering algorithm is proposed to reduce mixed-noise. The performance of the proposed filter is quantitatively evaluated by use of the normalized mean square errors (NMSE). The experimental results show that the performance of the proposed filter is obtained between 0.96 and 2.5 times better than that of weighted-D filter in NMSE evaluation.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.112-114
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• 2009

In this paper, a PN code tracking loop with extended Kalman filter (EKF) is proposed for a direct-sequence spread-spectrum. EKF is used to estimate amplitude and delay in a multipath fading channel. It is shown that tracking error performance is significantly improved by EKF compared with a conventional tracking loop.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.909-913
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• 1998

Transient and static characteristics of HVDC inverter can be analyzed with various simulation tools. For the optimal filter design, various performance criteria are proposed. In this paper, performance index is calculated based on proposed per phase equivalent circuit. Voltage and harmonic and filter power loss are selected as criteria. Optimization procedure is performed to find optimal passive filter parameters. Dynamic characteristics is also analyzed with proposed equivalent circuit.

• Journal of the Korean Data and Information Science Society
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• 제15권2호
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• pp.499-506
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• 2004

The Unscented Kalman Filter is known to outperform the Extended Kalman Filter for the nonlinear state estimation with a significance advantage that it does not require the computation of Jacobian but EKF has a competitive advantage to the UKF on the performance time. We compare both algorithms on training the artificial neural network. The validation data set is used to estimate parameters which are supposed to result in better fitting for the test data set. Experimental results are presented which indicate the performance of both algorithms.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권7호
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• pp.444-451
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• 2004

Conventional magnetic levitation systems could show unsatisfactory performance under air-gap disturbance due to rail irregularities. In this paper, we propose a feedback control system with discrete Kalman filter for air-gap disturbance attenuation. It is shown that excellent system performance can be obtained with the use of discrete Kalman filter, and that results from experiments agree well with those of simulations.