• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.5
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• pp.418-426
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• 2016

This paper analyzes the effect of resistance error to the performance of sensorless drive system of surface-mounted permanent magnet synchronous machine (SMPMSM) based on the back-EMF observer. The analysis shows that the bandwidth of the entire sensorless drive system decreased in the low-speed region when using smaller resistance value than the actual one in the back-EMF observer. Even if the back-EMF observer invokes estimation error, the entire sensorless drive system does not make any steady-state position error. These characteristics may have positive effects such as extension of the low speed limit that goes further down in the sensorless drive. The validity of the analysis is verified by the experimental setup comprising the MG set.

• Journal of Broadcast Engineering
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• v.17 no.1
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• pp.81-94
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• 2012

Several methods which utilize the phase of Zernike moments (ZMs) to estimate the rotation angle have shown good performance in terms of accuracy. In this paper, we provides the performance comparison results of the existing rotation angle estimation methods based on ZMs and propose an extension of Revaud et al.'s method [1] which utilizes the phase of ZMs; the proposed method uses angular radial transform coefficients instead of ZMs and yields better performance than the ZMs based methods in terms of accuracy. A set of ART can describe angular variation of image more intensively than ZMs, it enables more accurate estimation of the rotation angle than ZMs. In the experiments, the proposed method outperforms ZMs based method. Comparisons were made in terms of the root mean square error vs. the coverage on MPEG-7 shape dataset.

• Journal of Broadcast Engineering
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• v.12 no.5
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• pp.503-515
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• 2007

A new fast motion estimation algorithm is presented in this paper. The algorithm, named Enhanced Cross-Diamond Search (ECDS), is based on the Diamond Search (DS) algorithm. The DS algorithm, even though faster than the most well-known algorithms, was found not to be very robust in terms of objective and subjective qualities for several sequences and the algorithm searches unnecessary candidate blocks. We propose a novel ECDS algorithm using a small cross search as the initial step, and large/small DS patterns as subsequent steps for fast block motion estimation. Experimental results show that the ECDS is much more robust, provides a faster searching speed, and smaller distortions than other popular fast block-matching algorithms.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.4
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• pp.265-271
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• 2015

This study proposes an algorithm for recognizing apple trees in images and detecting apples to measure the number of apples on the trees. The proposed algorithm explores whether there are apple trees or not based on the number of image block-unit edges, and then it detects apple areas. In order to extract colors appropriate for apple areas, the CIE $L^*a^*b^*$ color space is used. In order to extract apple characteristics strong against illumination changes, modified census transform (MCT) is used. Then, using the AdaBoost learning algorithm, characteristics data on the apples are learned and generated. With the generated data, the detection of apple areas is made. The proposed algorithm has a higher detection rate than existing pixel-based image processing algorithms and minimizes false detection.

• International Journal of Computer Science & Network Security
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• v.23 no.9
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• pp.157-161
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• 2023

Reliability is one of the computable quality features of the software. To assess the reliability the software reliability growth models(SRGMS) are used at different test times based on statistical learning models. In all situations, Tradational time-based SRGMS may not be enough, and such models cannot recognize errors in small and medium sized applications.Numerous traditional reliability measures are used to test software errors during application development and testing. In the software testing and maintenance phase, however, new errors are taken into consideration in real time in order to decide the reliability estimate. In this article, we suggest using the Weibull model as a computational approach to eradicate the problem of software reliability modeling. In the suggested model, a new distribution model is suggested to improve the reliability estimation method. We compute the model developed and stabilize its efficiency with other popular software reliability growth models from the research publication. Our assessment results show that the proposed Model is worthier to S-shaped Yamada, Generalized Poisson, NHPP.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.5
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• pp.38-44
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• 2007

This paper presented a location and attitude estimation scheme of a capsule endoscope based on ultrasonic ranging. The scheme comprised eight on-capsule ultrasonic sensors to alleviate measurement errors due to irregularities in human body ultrasonic characteristics. It calculated the coordinate values and angles in a Cartesian coordinate system. The Matlab simulation reflecting random errors yielded the average deviations of 0.8mm in the location and $0.2^{\circ}$ in the attitude angle. These values are far smaller than normal intestine movement ranges inside human body, and will contribute accurate diagnosis of intestine.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.9
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• pp.2626-2641
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• 2024

Images taken in low lamination condition suffer from low contrast and loss of information. Low lumination image enhancement algorithms are required to improve the quality and broaden the applications of such images. In this study, we proposed a new Low lumination image enhancement architecture consisting of a transformer-based curve learning and an encoder-decoder-based texture enhancer. Considering the high effectiveness of curve matching, we constructed a transformer-based network to estimate the learnable curve for pixel mapping. Curve estimation requires global relationships that can be extracted through the transformer framework. To further improve the texture detail, we introduced an encoder-decoder network to extract local features and suppress the noise. Experiments on LOL and SID datasets showed that the proposed method not only has competitive performance compared to state-of-the-art techniques but also has great efficiency.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.3
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• pp.9-18
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• 2001

In this paper, we present the joint symbol detection and channel estimation for an orthogonal frequency division multiplexing (OFDM) system in fading channels. The proposed methods are based on decision-directed channel estimation (DDCE) method and their symbol detection is achieved by using Viterbi algorithm. This Viterbi decision-directed channel estimation (VDDCE) method tracks time-varying channels and detects a maximum likelihood symbol sequence. Recursive Viterbi decision-directed channel estimation (RVDDCE) method based on VDDCE method is proposed to shorten the detecting depth. In this method, channel estimate and Viterbi processing are recursively performed every interval of training symbol. Also, average chann'el estimation (ACE) technique to reduce the effect of additive white Gaussian noise (AWGN) is applied VDDCE method and RVDDCE method. These proposed methods arc demonstrated by computer simulation.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.616-619
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• 2003

In this paper, we develop an input device equipped with accelerometers and gyroscopes. The installed sensors measure the inertial measurements i.e., accelerations and angular rates produced by the movement of the system when a user is writing on the plane surface or in the three dimensional space. The gyroscope measurement are integrated once to give the attitude of the system and consequently used to remove the gravity included in the acceleration measurements. The compensated accelerations bin doubly integrated to yield the position of the system. Due to the integration processes involved in recovering the users'motions, the accuracy of the position estimation significantly deteriorates with time. Among various error sources of the system incorrect estimation of attitude causes the largest portion of the positioning error since the gravity is not fully cancelled. In order to solve this problem, we propose a Kalman filler-based attitude estimation algorithm which fuses measurement data from accelerometers and gyroscopes by fuzzy logic approach. In addition, the online calibration of the gyroscope biases are performed in parallel with the attitude estimation to give more accurate attitude estimation. The effectiveness and the feasibility of the presented system is demonstrated through computer simulations and actual experiments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5A
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• pp.423-431
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• 2011

In this paper, carrier frequency offset and 2-D AoA (Angle-of-Arrival) estimation methods are proposed for an OFDM-based MRS (Mobile Relay Station) with UCA (Uniform Circular Array). The proposed methods are performed by using the preamble symbol in downlink and can improve the performance of CFO estimation significantly, compared with the conventional method. The proposed methods can be divided into two methods (method 1 and method 2) depending on the order of the AoA estimation and CFO estimation. It is shown by computer simulation under Mobile WiMAX environments that the proposed methods can estimate the CFOs and AoAs of adjacent BSs effectively.