• International Journal of Fuzzy Logic and Intelligent Systems
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• v.13 no.3
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• pp.186-199
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• 2013

We pose pattern classification as a density estimation problem where we consider mixtures of generative models under partially labeled data setups. Unlike traditional approaches that estimate density everywhere in data space, we focus on the density along the decision boundary that can yield more discriminative models with superior classification performance. We extend our earlier work on the recursive estimation method for discriminative mixture models to semi-supervised learning setups where some of the data points lack class labels. Our model exploits the mixture structure in the functional gradient framework: it searches for the base mixture component model in a greedy fashion, maximizing the conditional class likelihoods for the labeled data and at the same time minimizing the uncertainty of class label prediction for unlabeled data points. The objective can be effectively imposed as individual mixture component learning on weighted data, hence our mixture learning typically becomes highly efficient for popular base generative models like Gaussians or hidden Markov models. Moreover, apart from the expectation-maximization algorithm, the proposed recursive estimation has several advantages including the lack of need for a pre-determined mixture order and robustness to the choice of initial parameters. We demonstrate the benefits of the proposed approach on a comprehensive set of evaluations consisting of diverse time-series classification problems in semi-supervised scenarios.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.156-166
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• 2000

A rate-distortion based segmentation using recursive merging is presented, which considers texture as a homogeneity by adopting the procedure of a generalized texture approximation. The texture in a region is approximated by SA-DCT and a set of two uniform quantizers with fixed step sizes, one for DC and another for AC. Using the approximated texture, we calculated the rate-distortion based cost. The segmentation using recursive merging is performed by using the rate-distortion based cost. Experimental results for 256$\times$256 Lena show that the region-based coding using the proposed segmentation yields the PSNR improvements of 0.8~ 1.0 dB and 1.2~1.5 dB over that using the rate-distortion based segmentation with DC approximation only and JPEG, respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.12
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• pp.2326-2339
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• 2011

To reduce the implementation complexity of the Vertical Bell Labs layered space-time (V-BLAST) systems with respect to the zero-forcing (ZF) criterion, a computationally efficient recursive algorithm is proposed. A fast implementation of the proposed algorithm is developed and its complexity is analyzed in detail. The proposed algorithm matches the ZF-OSIC detection well, and its three significant advantages can be demonstrated by analyses and simulations. Firstly, its speedups over the conventional ZF-OSIC with norm-based ordering, the original fast recursive algorithm (FRA) and the fastest known algorithm (FKA) in the number of flops are 1.58, 2.33 and 1.22, respectively. Secondly, a much simpler implementation than FRA and FKA can be expected. Finally, the storage requirements are lower than those of FRA and FKA. These advantages make the proposed algorithm more efficient and practical.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.3
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• pp.67-73
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• 2006

In this paper, a reconfigurable model following flight control method is proposed based on direct adaptive scheme using parameter estimation. Adaptive control scheme updates the control gains to make the system output follow the reference output even when fault occurs. By adopting the frequency domain parameter estimation method, system changes by the fault can be estimated. Recursive Fourier transformation is used for system identification. Using recursive Fourier transform, the proposed adaptive control algorithm guarantees the system stability and improves the system characteristics. To evaluate the performance of proposed control method, numerical simulations are performed.

• The Journal of Korea Robotics Society
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• v.13 no.1
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• pp.55-62
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• 2018

In this paper, a method for estimation of external force on an end-effector using joint torque sensor is proposed. The method is based on portion of measure torque caused by external force. Due to noise in the torque measurement data from the torque sensor, a recursive least-square estimation algorithm is used to ensure a smoother estimation of the external force data. However it is inevitable to create a delay for the sensor to detect the external force. In order to reduce the delay, modified recursive least-square is proposed. The performance of the proposed estimation method is evaluated in an experiment on a developed six-degree-of-freedom robot. By using NI DAQ device and Labview, the robot control, data acquisition and The experimental results output are processed in real time. By using proposed modified RLS, the delay to estimate the external force with the RLS is reduced by 54.9%. As an experimental result, the difference of the actual external force and the estimated external force is 4.11% with an included angle of $5.04^{\circ}$ while in dynamic state. This result shows that this method allows joint torque sensors to be used instead of commonly used external sensory system such as F/T sensors.

• Journal of the Korea Society of Computer and Information
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• v.11 no.2 s.40
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• pp.263-273
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• 2006

The remarkable development of the internet causes us to have too many homepages and content, to be specialized and subdivided, and to need 'CMS'(Content Management System). Currently, CMS have been developed by many solution providers and studied in many ways. However, it is hard to find a system which is able to construct the specified Culture & Tourism content rapidly and managed them efficiently. Step on these requirement, this paper focus on design and implementation of unified CMS based on recursive relation object model which can be satisfied the demand of the usual people's information service of Culture & Tourism and which can be installed and managed the standardized Culture & Tourism content easily.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.10
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• pp.43-48
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• 2010

In general, in order to reduce an initial cell searching time, W-CDMA systems adopt a three-step cell search scheme: slot synchronization, frame synchronization, and primary scrambling code identification. We consider the second step (frame synchronization), in which a coherent detection using P-SCH (primary synchronization channel) is possible. In this paper, we propose a new coherent detection scheme, where a first order recursive filter is used to enhance channel estimation performance. Computer simulation results indicate that the detection performance of the proposed scheme can be robust over large range of frequency offset.

• Journal of Drive and Control
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• v.14 no.3
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• pp.40-49
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• 2017

This study presents an online estimation of an excavator's rotational inertia by using recursive least square with forgetting. It is difficult to measure rotational inertia in real systems. Against this background, online estimation of rotational inertia is essential for improving safety and automation of construction equipment such as excavators because changes in inertial parameter impact dynamic characteristics. Regarding an excavator, rotational inertia for swing motion may change significantly according to working posture and digging conditions. Hence, rotational inertia estimation by predicting swing motion is critical for enhancing working safety and automation. Swing velocity and damping coefficient were used for rotational inertia estimation in this study. Updating rules are proposed for enhancing convergence performance by using the damping coefficient and forgetting factors. The proposed estimation algorithm uses three forgetting factors to estimate time-varying rotational inertia, damping coefficient, and torque with different variation rates. Rotational inertia in a typical working scenario was considered for reasonable performance evaluation. Three simulations were conducted by considering several digging conditions. Presented estimation results reveal the proposed estimation scheme is effective for estimating varying rotational inertia of the excavator.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.237-239
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• 2018

This paper proposes an on-line estimation algorithm of internal resistance of Li-ion battery based on the recursive least squares method to prevent the overvoltage and undervoltage casing degradation of life cycle of battery. An equivalent circuit model with single time constant is adopted, and under assumptions that the terminal voltage, current and SOC are measured accurately, the discrete time based nonlinear equation of the model can be converted to the linear equation which can be applied to recursive least squares method. Since the coefficients of the discrete time linear equation can be expressed by the parameters of the equivalent circuit model, it is shown that an internal resistance (Ri) can be estimated in real time using the least square method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.6
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• pp.609-615
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• 2000

The energy conservation is one of the most important issues in recent years. Especially, the energy conservation through improved control strategies is one of the most highly possible area to be implemented in the near future. The energy conservation of the ice storage system can be accomplished through the improved control strategies. A real time building load prediction algorithm was developed. The expected highest and the lowest outdoor temperature of the next day were used to estimate the next day outdoor temperature profile. The measured dry bulb temperature and the measured building load were used to estimate system parameters by using the on-line weighted recursive least square method. The estimated hourly outdoor temperatures and the estimated hourly system parameters were used to predict the next day hourly building loads. In order to see the effectiveness of the building load prediction algorithm, two different types of building models were selected and analysed. The simulation results show less than 1% in error for the prediction of the next day building loads. Therefore, this algorithm may successfully be used for the development of improved control algorithms of the ice storage system.