• 한국정보전자통신기술학회논문지
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• 제13권2호
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• pp.153-158
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• 2020

본 논문에서는 무선 통신 환경에서 잡음 및 간섭을 제거하여 원하는 목표물을 추정하는 알고리즘을 연구하였다. 잡음과 간섭이 포함된 정보신호가 수신기에 입사하면 원하는 목표물을 정확히 추정하기 어렵기 때문에 잡음 및 간섭 신호를 제거하는 방법이 필수적이다. 수신 신호영역을 두 공간으로 분리하기 위해서 상관행렬, 공분산, 고유특성벡터, 고유치를 분석하여 전력 스펙트럼을 획득한다. 제안한 전력 스펙트럼은 잡음을 제거할 수 있는 알고리즘으로서 목표물 추정성능을 분석하기 위해서 기존의 알고리즘과 모의실험을 통해서 확인한다. 모의실험 결과로, 기존 알고리즘의 목표물방향 추정 분해능은 10°이상이지만, 제안 알고리즘의 분해능은 10°미만을 나타내었다. 제안 알고리즘이 기존 알고리즘보다 약 5°의 분해능이 향상 되었다. 본 연구에서 제안된 알고리즘이 목표물 추정 정확도와 분해능이 기존 알고리즘보다 우수함을 입증하였다.

• 유공압시스템학회논문집
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• 제4권4호
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• pp.1-7
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• 2007

Flow rate is one of the important variables for precise motion control and detection of the faults and fluid loss in many hydraulic components and systems. But in many cases, it is not easy to measure it directly. The orifice area of a servo valve by which the fluid flows is one of key factors to monitor the flow rate. In this paper, we have constructed an estimation algorithm for the effective orifice area by using the model of a servo valve cylinder control system and Kalman filter algorithm. Without geometry information about the servo valve, it is shown that the effective orifice area can be estimated by using only displacement and pressure data corrupted with noise. And the effect of the biased sensor data and system parameter errors on the estimation results are discussed. The paper reveals that sensor calibration is important in accurate estimation and plausible parameter data such as oil bulk modulus and actuator volume are acceptable for the estimation without any error. The estimation algorithm can be used as an useful tool for detecting leakage, monitoring malfunction and/or degradation of the system performance.

• 전력전자학회논문지
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• 제24권2호
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• pp.92-98
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• 2019

Accurate estimation of motor parameters is required in some motor control applications. For example, the value of stator resistance is required for stator flux-oriented control mostly used in doubly fed induction generator systems. Stator resistance is not a constant value and continuously changes due to the rise in temperature during motor operation. Estimation errors degrade the control performance. Hence, this study proposes a simple stator resistance estimation method. In this scheme, the differential components of voltage and current values are used to eliminate the dead-time effect, and Kalman filter algorithm is applied to reduce the error according to measurement noise. Simulation and experimental results obtained with a permanent magnet motor show the validity of the proposed algorithm.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.717-720
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• 2000

The sensorless scheme for Switched Reluctance Motor(SRM) dives must have the robustness and reliability because the noise and error are sensitive. These elements make electrically noisy environments due to the proximity of high current power circuits with small signal electronic circuits when SRM drives. Also the leakage inductances and finite coupling capacitances these can cause the noise on any low voltage current and voltage measurement. the error can occur because the current and voltage including the noise are used as the input of sensorless algorithm In this paper the high robustness and resistance of input noise are described and the fuzzy logic based rotor estimation algorithm is used to reduce the tolerance of input data.

• 전기학회논문지P
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• 제61권2호
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• pp.87-92
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• 2012

Voltage and current phasor estimation has been executed by GPS-based synchronized PMU, which has become an important way of wide-area blackout protection for the prevention of expending faults in a power system. The PMU technique can not easily get the field data and it is impossible to share information, so that there has been used a FNET(Frequency Monitoring Network) method for the wide-area intelligent protection in USA. It consists of FDR(Fault Disturbance Recorder) and IMS(Information Management System). Therefore, FDR must provide an optimal frequency estimation method that is robust to noise and failure. In this paper, we present comparative studies for the frequency estimation method using IRDWT(Improved Recursive Discrete Wavelet Transform), FRDWT(Fast Recursive Discrete Wavelet Transform), and DFT(Discrete Fourier Transform). The Republic of Korea345[kV] power system modeling data by EMTP-RV are used to evaluate the performance of the proposed two kinds of RDWT(Recursive Discrete Wavelet Transform) and DFT. The simulation results show that the proposed frequency estimation technique using FRDWT could be the optimal frequency measurement method, and thus be applied to FDR.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.283-284
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• 2008

• 한국항행학회논문지
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• 제16권6호
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• pp.975-981
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• 2012

서로 다른 품질을 요구하는 데이터들의 동시 전송 또는 효율적인 영상전송시스템에 응용될 수 있는 계층 16QAM (Quadrature Amplitude Modulation) 시스템에 대한 SNR 추정성능에 대해 분석한다. 계층 16QAM은 계층 변조파라미터를 제어하여 성좌점들의 형태를 변형시켜 사용자에게 고품질과 저품질 데이터서비스를 동시에 제공할 수 있는 변조 시스템이다. AWGN (Additive White Gaussian Noise) 채널환경에서 계층 16QAM 시스템에서 계층변조파라미터와 성좌점별 특성을 고려한 SNR (Signal to Noise power Ratio) 추정성능 특성을 분석하였다. 시뮬레이션 결과, 계층 16QAM의 여러성좌점들 중에 SNR 추정이 상대적으로 정확하게 이루어지는 성좌점이 존재함을 확인하였고, 계층변조파라미터 값에 따라 SNR 추정이 유리한 영역이 달라진다는 것을 알아내었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2357-2380
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• 2019

In this paper, we investigate the impact of hardware impairments (HWIs) on the performance of a downlink massive MIMO system. We consider a single-cell system with maximum ratio transmission (MRT) as precoding scheme, and with all the HWIs characteristics such as phase noise, distortion noise, and amplified thermal noise. Based on the system model, we derive closed-form expressions for a typical user data rate under two scenarios: when a common local oscillator (CLO) is used at the base station and when separated oscillators (SLOs) are used. We also derive closed-form expressions for the downlink transmit power required for some desired per-user data rate under each scenario. Compared to the conventional system with ideal transceiver hardware, our results show that impairments of hardware make a finite upper limit on the user's downlink channel capacity; and as the number of base station antennas grows large, it is only the hardware impairments at the users that mainly limit the capacity. Our results also show that SLOs configuration provides higher data rate than CLO at the price of higher power consumption. An approach to minimize the effect of the hardware impairments on the system performance is also proposed in the paper. In our approach, we show that by reducing the cell size, the effect of accumulated phase noise during channel estimation time is minimized and hence the user capacity is increased, and the downlink transmit power is decreased.

• 전기의세계
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• 제28권3호
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• pp.57-64
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• 1979

The static state estimation are divided into two groups; estimation and detection & identification. This paper centers on detection and identification algorithm. Especially, the identification of line errors is focused on and is performed by the extended W.L.S. algorithm with line swithching states. Here, line switching states mean the discrete values of line admittance which are influenced by unexpected line switching. The numerical results are obtained from the assumption that the noise vector is independent zero mean Gaussian random variables.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1993년도 춘계학술대회
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• pp.74-77
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• 1993

Estimation and removal of power line interference in the electrocardiogram using adaptive noise cancelling techniques is presented. The system identification concepts are used to design the noise cancelling filter and the prediction error method is used to adjust filter coefficients. Computer simulation were performed to compare this method with the Lekov's method.