• 제어로봇시스템학회논문지
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• 제6권11호
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• pp.1039-1044
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• 2000

In this paper, the error caused by the measurement delay in INS/GPS integrated systems with Kalman filtering is defined and analyzed through the analytical method and the simulation. It is proved that the error of measurement delay causes not only the position error but also the estimate error of the x-axis accelerometer bias when a vehicle turns. And the estimation method of the delay time and the compensation method using an extrapolation method are presented. The performance of the compensation method is shown by the analytic method and the simulation.

• 제어로봇시스템학회논문지
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• 제13권7호
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• pp.637-648
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• 2007

This paper presents a sensor fusion method based on indirect Kalman filter(IKF) for error compensation of low-cost inertial sensors and its application to the determination of attitude and position of small flying robots. First, the analysis of the measurement error characteristics to zero input is performed, focusing on the bias due to the temperature variation, to derive a simple nonlinear bias model of low-cost inertial sensors. Moreover, from the experimental results that the coefficients of this bias model possess non-deterministic (stochastic) uncertainties, the bias of low-cost inertial sensors is characterized as consisting of both deterministic and stochastic bias terms. Then, IKF is derived to improve long term stability dominated by the stochastic bias error, fusing low-cost inertial sensor measurements compensated by the deterministic bias model with non-inertial sensor measurement. In addition, in case of using intermittent non-inertial sensor measurements due to the unreliable data link, the upper and lower bounds of the state estimation error covariance matrix of discrete-time IKF are analyzed by solving stochastic algebraic Riccati equation and it is shown that they are dependant on the throughput of the data link and sampling period. To evaluate the performance of proposed method, experimental results of IKF for the attitude determination of a small flying robot are presented in comparison with that of extended Kaman filter which compensates only deterministic bias error model.

• 한국통신학회논문지
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• 제29권2C호
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• pp.298-305
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• 2004

본 논문은 워드길이가 W 비트인 입력으로부터 W 비트를 출력하는 고정길이 modified Booth 곱셈기에 대한 오차보상 방법을 설명한다. 효율적으로 양자화 오차를 보상하기 위해 Booth 인코더의 출력정보를 이용하여 오차보상 바이어스를 생성한다. 절단된 부분이 양자화 오차에 미치는 영향에 따라 두 그룹(major or minor group)으로 나누고, 각 그룹에 서로 다른 오차보상 방법을 적용한다. 기존 방법과 비교하여 제안한 방법이 오차보상 바이어스를 생성하는 회로의 하드웨어 오버헤드는 비슷하면서 약 50％ 정도 양자화 오차가 적음을 시뮬레이션을 통해 보인다. 또한, 면적과 전력소모 면에서 제안한 고정길이 곱셈기가 이상적인 곱셈기 보다 약 40％ 정도 적게 나타났다.

• The Journal of the Acoustical Society of Korea
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• 제22권4E호
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• pp.150-154
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• 2003

The distortion effects of microphones have been analyzed and compensated at mel-frequency feature domain. Unlike popular bias removal algorithms a linear transformation of mel-frequency spectrum is incorporated. Although a diagonal matrix transformation is sufficient for medium-quality microphones, a full-matrix transform is required for low-quality microphones with severe nonlinearity. Proposed compensation algorithms are tested with HTIMIT database, which resulted in about 5 percents improvements in recognition rate over conventional CMS algorithm.

• 한국인터넷방송통신학회논문지
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• 제20권4호
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• pp.129-133
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• 2020

본 논문에서는 W-대역 저잡음증폭기의 온도에 따른 이득 변동을 경감시킬 수 있는 온도보상회로를 기술하였다. 제안된 캐스코드 온도보상 바이어스회로는 공통-소스 저잡음증폭기의 게이트 바이어스를 자동으로 조절하여 소신호 이득의 변화를 억제한다. 설계된 회로는 100-nm GaAs pHEMT 공정 디자인킷으로 구현되었다. 제안된 바이어스 회로를 적용한 W-대역 저잡음증폭기의 시뮬레이션 이득값은 -35~71℃ 범위에서 20 dB 이상, ±0.8 dB 내의 변동값을 보였다. 본 논문에서 제시한 회로는 레이더용 밀리미터파 수신기에 적용되어 안정적인 성능을 낼 수 있을 것으로 기대된다.

• 제어로봇시스템학회논문지
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• 제17권8호
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• pp.783-789
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• 2011

Target tracking performance improvement using multi-sensor data fusion is a challenging work. However, biases in the measurements should be removed before various data fusion techniques are applied. In this paper, a bias removing algorithm using measurement data from multi-radar tracking systems is proposed and evaluated by computer simulation. To predict bias estimation performance in various geometric relations between the radar systems and target, a system observability index is proposed and tested via computer simulation results. It is also studied that target tracking which utilizes multi-sensor data fusion with bias-removed measurements results in better performance.

• Journal of Positioning, Navigation, and Timing
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• 제13권2호
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• pp.179-187
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• 2024

The performance of a Strapdown Inertial Navigation System (SDINS) relies heavily on the accuracy of sensor error calibration. Systematic calibration is usually employed when only a 2-axis turntable is available. For systematic calibration, the body frame is commonly defined with respect to sensor axes for ease of computation. The drawback of this approach is that sensor axes may undergo time-varying deflection under temperature change, causing pseudo gyro bias. The effect of pseudo gyro bias on navigation performance is negligible for low grade navigation systems. However, for higher grade systems undergoing rapid temperature change, the error is no longer negligible. This paper describes in detail conditions leading to the presence of pseudo gyro bias, and proposes two techniques for mitigating the error. Experimental results show that applying these techniques improves navigation performance for precision SDINS, especially under rapid temperature change.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2521-2524
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• 2003

Since inertial sensor errors which increase with time are caused by initial orientation error and sensor errors (accelerometer bias and gyro drift bias), the accuracy of these devices, while still improving, is not adequate for many of today's high-precision, long-duration sea, aircraft, and long-range missile missions. This paper presents a navigation error compensation scheme for Strap-Down Inertial Navigation System (SDINS) using Line-Of-Sight(LOS) vector from star sensor. To be specific, SDINS error model and measurement equation are derived, and Kalman filter is implemented. Simulation results show the bounded-ness of position and attitude errors.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.888-893
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• 2005

Since inertial sensor errors which increase with time are caused by initial orientation error and sensor errors(accelerometer bias and gyro drift bias), the accuracy of these devices, while still improving, is not adequate for many of today's high-precision, long-duration sea, aircraft, and long-range flight missions. This paper presents a navigation error compensation scheme for Strap-Down Inertial Navigation System(SDINS) using star tracker. To be specific, SDINS error model and measurement equation are derived, and Kalman filter is implemented. Simulation results show the boundedness of position and attitude errors.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1701-1703
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• 2006

Here we describe a novel driving scheme in the form of negative AC bias stress (NAC) to compensate shift in the threshold voltage for hydrogenated amorphous silicon (${\alpha}$-Si:H) thin film transistor (TFT) for AMOLED applications. This scheme preserves the threshold voltage shift of ${\alpha}$-Si:H TFT for infinitely long duration of time(>30,000 hours) and thereby overall performance, without using any additional TFTs for compensation. We briefly describe about the possible driving schemes in order to implement for real time AMOLED applications. We attribute most of the results based on concept of plugging holes and electrons across the interface of the gate insulator in a controlled manner.