• 제어로봇시스템학회논문지
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• 제7권8호
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• pp.711-715
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• 2001

In this paper, an effective filter structure for filtering of target glint in tracking radar systems is used to improve the performance of CLOS(Command to Line-Of-Sight) guidance. The filter decouples range and angel channels to that it has a sound mathematical basis as well as computation efficiency as applied to the IMM algorithm. The effective filter structure in conjunction with CLOS guidance is tested by a series of simulation runs and it is shown to have superior performance compared with the other filter structures.

• 대한음성학회지:말소리
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• 제53호
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• pp.93-102
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• 2005

The performance of a speech recognition system is generally degraded in telephone environment because of distortions caused by background noise and various channel characteristics. In this paper, data-driven temporal filters are investigated to improve the performance of a specific recognition task such as telephone speech. Three different temporal filtering methods are presented with recognition results for Korean connected-digit telephone speech. Filter coefficients are derived from the cepstral domain feature vectors using the principal component analysis. According to experimental results, the proposed temporal filtering method has shown slightly better performance than the previous ones.

• Journal of electromagnetic engineering and science
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• 제11권2호
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• pp.91-96
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• 2011

In this paper, we propose a microstrip bandpass filter using stepped-impedance coupled-line hairpin resonators. The stepped-impedance coupled-line hairpin resonator has extended harmonic suppression in comparison with a conventional hairpin resonator due to transmission zero and the movement of harmonic frequencies resulting from the stepped-impedance characteristic. A high-pass type impedance/admittance inverter is employed in order to improve the lower frequency skirt characteristics of the passband. A 4-pole bandpass filter is designed and fabricated at 1.8 GHz. The measured results show the excellent attenuation performance at the stopband which is greater than 30 dB up to 10 GHz.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권9호
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• pp.2348-2360
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• 2023

As science and technology evolve, object detection of moving objects has been widely used in the context of machine learning and artificial intelligence. Traditional moving object detection algorithms, however, are characterized by relatively poor real-time performance and low accuracy in detecting moving objects. To tackle this issue, this manuscript proposes a modified Kalman filter algorithm, which aims to expand the equations of the system with the Taylor series first, ignoring the higher order terms of the second order and above, when the nonlinear system is close to the linear form, then it uses standard Kalman filter algorithms to measure the situation of the system. which can not only detect moving objects accurately but also has better real-time performance and can be employed to predict the trajectory of moving objects. Meanwhile, the accuracy and real-time performance of the algorithm were experimentally verified.

• 한국측량학회지
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• 제37권5호
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• pp.367-377
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• 2019

As an alternative navigation system for the non-GNSS (Global Navigation Satellite System) environment, a new type of DBRN (DataBase Referenced Navigation) which applies both gravity gradient and terrain, and combines filter-based algorithm with profile matching was suggested. To improve the stability of the performance compared to the previous study, both centralized and decentralized EKF (Extended Kalman Filter) were constructed based on gravity gradient and terrain data, and one of filters was selected in a timely manner. Then, the final position of a moving vehicle was determined by combining a position from the filter with the one from a profile matching. In the simulation test, it was found that the overall performance was improved to the 19.957m by combining centralized and decentralized EKF compared to the centralized EKF that of 20.779m. Especially, the divergence of centralized EKF in two trajectories located in the plain area disappeared. In addition, the average horizontal error decreased to the 16.704m by re-determining the final position using both filter-based and profile matching solutions. Of course, not all trajectories generated improved performance but there is not a large difference in terms of their horizontal errors. Among nine trajectories, eights show smaller than 20m and only one has 21.654m error. Thus, it would be concluded that the endemic problem of performance inconsistency in the single geophysical DB or algorithm-based DBRN was resolved because the combination of geophysical data and algorithms determined the position with a consistent level of error.

• 한국위성정보통신학회논문지
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• 제12권3호
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• pp.63-68
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• 2017

영상 레이다(Synthetic Aperture Radar)는 전자파를 이용하여 영상을 생성함에 따라 주 야간 상황과 무관하게 안정적인 광역 관측자료를 확보할 수 있으며 기상 제약 환경과 무관하게 전략적 상업적 목적으로의 감시 및 관찰 기능을 요구하는 임무에 광범위하게 활용될 수 있다. 그러나 SAR 위성 시스템의 경우 넓은 대역의 주파수를 사용하기 때문에 인접대역을 사용하는 레이다 시스템 및 통신기기로부터 간섭 영향에 의해 영상품질을 저하시킬 수 있다. 본 논문에서는 SAR 영상의 품질향상을 위해 간섭 제거 기법인 고유치 기반 필터(Eigen-subspace based Filter) 기법을 제안하였으며, SAR 위성의 간섭제거 알고리즘인 고유치 기반 필터 기법의 정량적인 성능 분석을 위해 일반적인 노치 필터(Notch Filter) 기법을 적용한 결과를 토대로 비교 검증하였다.

• 전기학회논문지
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• 제59권1호
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• pp.176-183
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• 2010

This paper presents some practical design issues that should be carefully considered when a notch filter is included in a linear feedback controller. A notch filter is generally used to compensate the effects of resonant modes that may result in poor performance. It is very common that the practical engineers prefer to add such a notch filter after having previously designed a feedback controller without the filter. It is known that the resulting performance by this approach is not seriously different from when a feedback controller is designed for a plant previously compensated by a notch filter. However, we will point out that there are some cases where both approaches have different performances. In order to show this, a low-order controller design using the partial model matching method has been applied to a linear time invariant (L Tn model. The results suggest that there is a tendency to achieve much better time responses in terms of reducing the overshoot and shortening the settling time, and in the frequency domain characteristics such as the sensitivity function and the stability margins when the design of a feedback controller after including a notch filter is carried out.

• 한국인터넷방송통신학회논문지
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• 제14권3호
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• pp.43-49
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• 2014

마크-젠더 변조기와 저역 통과 필터를 사용하여 광 듀오바이너리 신호를 생성하는 광 듀오바이너리 송신기의 전송 특성을 40Gbps에서 이론적으로 분석하였다. 광 듀오바이너리 시스템의 전송 성능은 송신기를 구성하는 저역 통과 필터와 광 필터 그리고 수신기내 필터의 대역폭에 따라 차이를 보였으며 각 필터들은 광 파워 스펙트럼에 각기 다른 영향을 주었다. 필터들의 최적화된 대역폭을 선택함으로써 광 듀오바이너리 신호 전송 시 부엽 발생과 리플을 억제시키고 분산 내성을 개선 할 수 있었다.

• 전기학회논문지P
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• 제65권3호
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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.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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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.