• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.6
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• pp.546-555
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• 2001

In this paper filtering techniques to reduce the adverse effects of motor leads on high-frequency PWM inverter fed AC motor drives are presented. The filter was designed to keep the motor terminal from the cable surge impedance to reduce overvoltage reflections ringing and the dv/dt, di/dt, at the motor terminals. Specially the output filter is used to limit the rate of the inverter output voltage and reduce common mode noise to the motor, The performance of the output filter is evaluated through simulations and experiment on PWM inverter-fed AC motor drive. An experimental PWM drive system reduction of conducted EMI was implemented on an available TMS320C31 microprocessor control board Finally, experimental result shows inverter output filter reduces more common mode voltage than low pass filter also reduce overoltage and ringing at the motor terminal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.11
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• pp.1714-1725
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• 1993

This paper analyzes the properties of such algorithm that corresponds to the nonlinear adaptive algorithm with additional update terms, parameterized by the scalar factors a1, a2, a3 and Presents its structure. The analysis of convergence leads to eigenvalues of the transition matrix for the mean weight vector. Regions in which the algorithm becomes stable are demonstrated. The time constant is derived and the computational complexities of MLMS algorithms are compared with those of the conventional LMS, sign, LFG, and QFG algorithms. The properties of convergence in the mean square are analyzed and the expressions of the mean square recursion and the excess mean square error are derived. The necessary condition for the CFG algorithm to be stable is attained. In the computer simulation applied to the system identification the CFG algorithm has the more computation complexities but the faster convergence speed than LMS, LFG and QFG algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12A
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• pp.1971-1977
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• 2001

Multipath Rayleigh fading channels for mobile radio transmission can be represented by the linear filter model, and depending on the delay path characteristics, only a selected number of taps may have significance in the receiver structure design. By using tap-selective equalization, reduction in both processing complexity and power consumption can be obtained. In this paper, we present an optimal tap selection method for a given channel model, and demonstrate the performance improvement over an existing method. We show the method performs the CFAR (Constant False Alarm Rate) detection when the noise power information is available, and derive exact expressions of the error probability for the case of noise power estimation. Using the derived formulas and simulation results, it is demonstrated that the error probability quickly approaches to the optimal performance as the number samples used for the noise power estimation increases.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.151-156
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• 2012

In this paper robust nonlinear image denoising algorithms are introduced for the distribution which is Gaussian in the center and Laplacian in the tails. The distribution is known as the least favorable ${\epsilon}$-contaminated normal distribution that maximizes the asymptotic variance. The proposed filter proves to be the maximum likelihood estimator under the heavy-tailed Gaussian noise environments. It is optimal in the respect of maximizing the efficacy under the above noise environment. Another filter for reducing impulsive noise is proposed by mixing with the myriad filter to propose an amplitude-limited myriad filter. Extensive experiment is conducted with images corrupted with ${\alpha}$-stable noise to analyze the behavior and performance of the proposed filters.

• Proceedings of the KAIS Fall Conference
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• 2011.12a
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• pp.262-265
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• 2011

본 연구는 탈진 기류 분사 시스템의 최적화 설계에 관한 기초 연구의 일환으로 전산유체역학(CFD)을 이용하여 일반 블로우 튜브와 단순 벤츄리 조합의 충격 기류(Pulse air jet) 방식의 탈진 장치에 대한 탈진 성능과 벤츄리 입구에 기류 유도용 구조물을 설치한 경우의 탈진 성능을 비교하였다. 각 Case별로 벤츄리 내부로 유입되는 탈진 공기량을 예측한 결과, case 2의 벤츄리 형상 개조시 case 1 보다 벤츄리로 유입되는 탈진 공기량이 약 20% 증폭되는 것으로 나타났다. 또한 필터백 표면에서의 탈진 기류 전달 분포를 예측한 결과, 모든 case가 필터백의 국한된 영역으로 탈진 기류가 집중됨을 알 수 있었다. 또한, case 2의 경우가 case 1보다 오히려 탈진 기류의 전달 수준이 불량함을 알 수 있다. 이는 case 2의 경우 벤츄리 입구에 기류 유도용 구조물을 설치한 것이 탈진 공기량을 증폭시키는데에는 도움이 되나, 오히려 벤츄리 내부로 유입된 탈진 기류의 직진성을 보완하여 필터백 내부에서 탈진 기류의 확장을 방해하기 때문인 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.172-172
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• 2017

본 연구는 차량의 AW(AutoWiping) 기능을 위해 장착된 강우센서를 이용하여 강우정보를 생산하는 기술을 개발하고자 하였다. AW(AutoWiping) 기능이란 차량 앞창(Windshield)에 빗방울이 맺히게 되면 광신호의 산란으로 인해 수광부에 들어오는 감소되는 광신호의 정도에 따라 차량 와이퍼의 속도를 결정해 주는 기능이다. 빗방울이 많이 맺힐수록 광신호는 감소되며 와이퍼는 더 빠른 속도로 작동을 하게 된다. 여기서 강우센서가 강우량이 많으면 감소된 광신호 데이터를 표출하는 현상을 이용하여 강우정보를 생산한다. 강우센서는 총 8개의 채널로 이루어져있고, 초당 250개의 광신호 데이터를 수집하며, 10분이면 약 120만 개의 데이터가 생산되게 된다. 이 대량의 데이터에서 정확한 강우량을 산출하기 위해 강우센서의 초기값과 와이퍼 이동시 발생하는 순간 이상치를 제거해야 한다. 하지만 일일이 수백만 개 이상의 데이터에서 모든 이상치를 제거하는 작업은 불가능하다. 따라서 이상치를 포함한 회귀 분석 방법을 연구하였고, 인공강우 발생기를 이용하여 광신호를 강우량으로 환산하는 2가지 회귀식이 유도되었다. 이들은 각각 이상치를 모두 포함시켜 독립변수(광신호)에 따라 종속변수(강우량)의 값이 변화하는 관계를 나타내는 선형회귀분석(model 1), 임계치를 정하여 일정 이상치가 제거된 신호만 통과시키는 대역통과 필터링 분석(model 2)으로 유도된 회귀식을 실강우에 회귀식을 적용하여 정확도를 분석하였다.

• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.53-58
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• 2016

In this paper, we propose a novel quadratic Kalman filter based object tracking algorithm using moving pictures. Quadratic Kalman filter, which is introduced recently, has not yet been applied to the problem of 3-dimensional (3-D) object tracking. Since the mapping of a position in 2-D moving pictures into a 3-D world involves non-linear transformation, appropriate algorithm must be chosen for object tracking. In this situation, the quadratic Kalman filter can achieve better accuracy than extended Kalman filter. Under the same conditions, we compare extended Kalman filter, unscented Kalman filter and sequential importance resampling particle filter together with the proposed scheme. In conculsion, the proposed scheme decreases the divergence rate by half compared with the scheme based on extended Kalman filter and improves the accuracy by about 1% in comparison with the one based on unscented Kalman filter.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1229-1235
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• 2003

When finite length image signal is decomposed into 2-band signal and synthesized using 2-band orthogonal wavelet transform, boundary signals are not reconstructed perfectly. To reconstruct them perfectly, the filters which are different from wavelet filter are applied to the boundary signals. Since the existing boundary filters show poor frequency characteristic, the improvement of performance is bounded in practical applications. In this paper, the design method of improvement of frequency characteristic is proposed using inserting a zero to boundary filters which can reconstruct the boundary regions perfectly. Even though the length of proposed boundary filters is shorter, they show 4.2dB∼6.59dB gains in pass band and stop band error power compared with existing boundary filters. But synthesis process is some complicated.

• The KIPS Transactions:PartB
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• v.12B no.4 s.100
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• pp.379-386
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• 2005

This paper provides a rigorous theory for analysis of quantization effects and optimum filter bank design in quantized multidimensional subband filter banks. Even though subband filter design has been a hot topic for last decades, a few results have been reported on the subband filter with a quantizer. Each pdf-optimized quantizer is modeled by a nonlinear gain-plus-additive uncorrelated noise and embedded into the subband structure. Using polyphase decomposition of the analysis/synthesis filter banks, we derive the exact expression for the output mean square quantization error. Based on the minimization of the output mean square error, the technique for optimal filter design methodology is developed. Numerical design examples for optimum nonseparable paraunitary and biorthogonal filter banks are presented with a quincunx subsampling lattice. Through the simulation, $10\~20\;\%$ decreases in MSE have been observed compared with subband filter with no quantizers especially for low bit rate cases.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.470-473
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• 1989

본 논문은 상태 변수 모델 하에서 유도된 최적 FIR 필터의 해를 이용한 새로운 이산 퓨리에 변환 방법을 제시한다. 이 방법은 측정 잡음 하에서 시변 하모닉스 성분을 추정하는데 특히 유용하여, 기존의 이산 퓨리에 변환 보다 훨씬 효과적인 노이즈 억제성능을 얻을 수 있으며 또한 칼만 필터를 사용한 하모닉스 추정 방법에서 발생하는 발산 문제를 해결할 수 있다. 그것은 유일한 필터 구간 내에서 BIBO 안정도를 향상 보장하는 FIR필터의 구조에서 야기된다. 한편 기존의 하모닉스 추정 방법들과 여러 가지 측면의 성능 비교가 있었고 시뮬레이션 예제를 통해 본 논문에서 제시한 방법의 효용성을 입증하였다.