• Journal of Communications and Networks
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• 제14권2호
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• pp.199-205
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• 2012

This work investigates the progressive linear precoder design for packet retransmissions in multi-input multi-output (MIMO) systems with multiple codewords and automatic repeat request (ARQ) bundling feedback. Assuming perfect channel state information, a novel progressive linear ARQ precoder is proposed in the perspective of minimizing the packet error rate. We devise the ARQ precoder by combining power loading and sub channel pairing between current retransmission and previous transmissions. Furthermore, we extend the design to the case that the channel estimation error exists. Numerical results show that the proposed scheme can improve the performance of MIMO ARQ systems significantly regardless of the channel estimation error.

• 제어로봇시스템학회논문지
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• 제3권3호
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• pp.244-251
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• 1997

In this paper, we propose a fault diagnosis algorithm to detect and isolate multiple faults in a system. The proposed fault diagnosis algorithm is based on a multiple fault classifier which consists of two ART2 NN(adaptive resonance theory2 neural network) modules and the algorithm is composed of three main parts - parameter estimation, fault detection and isolation. When a change in the system occurs, estimated parameters go through a transition zone in which residuals between the system output and the estimated output cross the threshold, and in this zone, estimated parameters are transferred to the multiple faults classifier for fault isolation. From the computer simulation results, it is verified that when the proposed diagnosis algorithm is performed successfully, it detects and isolates faults in the position control system of a DC motor.

• 대한전기학회논문지
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• 제34권3호
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• pp.107-114
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• 1985

This paper presents the iterative algorithm for obtaining the ME PSE(Maximum Entropy Power Spectral Estimation) of 2-dimensional signals. This problem involves a correction matching power spectral estimate that can be represented as the reciprocal of the spectral of 2-dimensional signals. This requires two matrix inversion every iterations. Thus, we compensate the matrix to be constantly positive definite with relaxational parameters. Using Row/Column decomposition Discrete Fourier Transform, we can decrease a calculation quantity. Using Lincoln data and white noise, this paper examines ME PSE algorithms. Finally, the results output at the graphic display device. The 2-dimensional data have the 3-dimensional axis components, and, this paper develops 3-dimensional graphic output algorithms using 2-dimensional DGL(Device Independent Graphic Library) which is prepared for HP-1000 F-series computer.

• Journal of Communications and Networks
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• 제9권3호
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• pp.254-264
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• 2007

A promising approach to improve the performance of mobile location system is the use of antenna arrays in both transmitter and receiver sides. Using advanced array signal processing techniques, such multiple-input multiple-output (MIMO) communication systems can offer more mobile location information by exploiting the spatial properties of the multipath channel. In this paper, we propose a novel approach to determine the position of mobile terminal based on estimated multipath signal parameters using only one base station in MIMO communication systems. This approach intends to minimize the error occurring from the estimation of multiple paths and gives an optimal estimation of the position of mobile terminal by simultaneously calculating a set of nonlinear location equations. This solution breaks the bottleneck of conventional mobile location systems which have to require multilateration of at least three base stations.

• 한국정밀공학회지
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• 제22권6호
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• pp.47-54
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• 2005

A dangerous event occurred at the field industry and mechanical system. At developed by SUNGGOKNANOTECH corp. a R-L clutches of a small and high capacity serves safety device from a variety environment of mechanical system, it permits transmission of driving torque from input to output shaft in both directions of rotation, but restrains any feedback torque of the driven load from rotating the output shaft in either direction. This study was carried out to demonstrate through finite element method and durability estimation for safety of the R-L clutches without sliding during the engagement process. As results, we organized about endurance test method when applied rated torque.

• 대한기계학회논문집A
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• 제28권11호
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• pp.1621-1628
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• 2004

This paper proposes a design methodology for the robust observer using the eigenstructure assignment in multi-output systems so that the observer is less sensitive to the ill-conditioning factors such as unknown initial estimation error, modeling error and measurement bias in transient and steady-state observer performance. The robustness of the observer can be achieved by selecting the desired eigenvector matrix to have a small condition number that guarantees the small upper bound of the estimation error. So the left singular vectors of the unitary matrix spanned by space of the achievable eigenvectors are selected as a desired eigenvectors. Also, this paper proposes how to select the desired eigenvector based on the measure of observability and designs the observer with small gain. An example of a spindle drive system is simulated to validate the robustness to the ill-conditioning factors in the observer performance.

• 한국정밀공학회지
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• 제13권5호
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• pp.38-43
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• 1996

Windowing routines have as their purpose the reduction of the sidelobes of a spectral output of the FFT or DFT routines. Windowing routines accomplish this by forcing the beginning and end of any sequence to approach each other in value. Since they must work with any sequence they force the beginning and ending samples near zero. To make up for this reduction in power, windowing routines give extra weight to the values near the middle of the sequence. The difference between windows is the way in which they transition from the low weights near the edges to the higher weights neqr the middle of the sequence. Signal-to-noise ratio(SNR) can be determined by the ratio of the output noisy signal variance to the input noisy signal variance of a window. Standard deviation of noise is reduced by windowing. Thus, the windowing operation improved the SNR of the noisy signal. This paper shows a performance estimation of windowing on a single tone with added Gaussian noise and uniform noise.

• 한국정밀공학회지
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• 제14권6호
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• pp.121-127
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• 1997

Multilayer feedforward networks may be applied to identify the deterministic relationship between input and output data. When the results from the network require a high level of assurance, consideration of the stochastic relationship between the input and output data may be very important. Variance is one of the effective parameters to deal with the stochastic relationship. This paper presents a new algroithm for a multilayer feedforward network to learn the variance of dispersed data without preliminary calculation of variance. In this paper, the network with this learning algorithm is named as a variance learning neural network(VALEAN). Computer simulation examples are utilized for the demonstration and the evaluation of VALEAN.

• 한국인터넷방송통신학회논문지
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• 제13권1호
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• pp.89-93
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• 2013

본 연구는 공간상에서 수신기에 입사하는 목표물 도래방향을 추정하는 것이다. 본 연구는 다중 입력 다중 출력 배열 안테나 시스템에서 상관성 간섭신호를 제거하기 위해서 제한 행렬을 이용하여 공분산 벡터를 제시하였고 비용함수와 최소 분산방법을 이용하여 목표물 도래방향을 추정하는 알고리즘을 제안하였다. 모의실험을 통하여 본 연구에서 제안된 알고리즘 성능을 기존 SPT_LCMV알고리즘과 비교분석하였다. 목표물 도래방향 추정에서 본 연구에서 제안한 방법이 기존 SPT_LCMV알고리즘보다 우수함을 나타내었다.

• 한국전자파학회논문지
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• 제19권4호
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• pp.461-469
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• 2008

본 논문은 MIMO OFDM 시스템에 적용 가능한 하이브리드 심볼 옵셋 추정 알고리즘을 제안한다. MIMO OFDM 시스템은 다중 송수신 안테나 시스템이므로 종래의 단일 송수신 안테나 시스템에 적용되는 알고리즘과는 다르게 다중 수신 안테나 시스템에서 사용하는 결합 기법을 고려하여 사용할 수 있다. 따라서 본 논문에서는 MIMO OFDM 시스템과 같은 다중 수신 안테나 시스템에서 적용 가능한 심볼 옵셋 추정 알고리즘을 제안하고, MIMO 시스템 환경에서 모의 실험하였으며, ISI가 심한 채널의 경우에는 제안하는 동일 이득 결합 상관 관계 알고리즘이 종래의 이른 심볼 옵셋 추정 알고리즘보다 이상적인 샘플 위치를 찾는 성능이 1.8배 우수함을 제시하였다.