• Journal of Korea Multimedia Society
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• v.20 no.10
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• pp.1637-1645
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• 2017

Target/Nontarget classification can be divided into the study of shape estimation of the target analysing reflected echo signal and of type classification of the target using acoustical features. In active sonar system, the feature vectors are extracted from the signal reflected from the target, and an classification algorithm is applied to determine whether the received signal is a target or not. However, received sonar signals can be distorted in the underwater environments, and the spatio-temporal characteristics of active sonar signals change according to the aspect of the target. In addition, it is very difficult to collect real sea-trial data for research. In this paper, target/non-target classification were performed using real sea-trial data. Feature vectors are extracted using MFCC(Mel-Frequency Cepstral Coefficients), filterbank energy in the Fourier spectrum and wavelet domain. For the performance verification, classification experiments were performed using backpropagation neural network classifiers.

• Journal of Korea Multimedia Society
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• v.19 no.10
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• pp.1775-1781
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• 2016

Generally, in the underwater target recognition, feature vectors are extracted from the target signal utilizing spatial information according to target shape/material characteristics. In addition, various signal processing techniques have been studied to extract feature vectors which are less sensitive to the location of the receiver. In this paper, we synthesized active echo signals using 3-dimensional highlight distribution. Then, Fractional Fourier transform was applied to echo signals to extract signal features. For the performance verification, classification experiments were performed using backpropagation and probabilistic neural network classifiers based on single aspect and multi-aspect method. As a result, we obtained a better recognition result using proposed feature extraction and multi-aspect based method.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.202-205
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• 2005

Our previous study showed that the overexpression of carboxypeptidase Y (CPY) of Saccharomyces cerevisiae in Escherichia coli resulted in the formation of insoluble inclusion bodies. To produce soluble CPY, we designed a novel Pichia pastoris expression system, in which the following were inserted into expression vectors: three different signal sequences derived from the mating factor a1 of S. cerevisiae, an inulinase of Kluyveromyces marxianus, and the endogenous signal sequence of CPY. The expression vector pHIL-D2-SSinul-proCPY was the most effective in the production of proCPY among the vectors examined. The purified active CPY was obtained from proCPY by treating with proteinase K, followed by QExcellose ion-exchange column chromatography.

• Journal of Power Electronics
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• v.17 no.4
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• pp.923-932
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• 2017

This paper proposes a novel scheme which can compensate the common-mode voltage (CMV) for five-level active neutralpoint clamped (5L-ANPC) inverters, which is based on modifying the space vector pulse width modulation (SVPWM) and adding an auxiliary leg to the inverter. For the modified SVPWM, only the 55 voltage vectors producing low CMV values among the 125 possible voltage vectors are utilized, which varies over the three voltage levels of $-V_{dc}/12$, 0 V, and $V_{dc}/12$. In addition, the compensating voltage, which is injected into the 5L-ANPC inverter system to cancel the remaining CVM through a common-mode transformer (CMT) is generated by the additional NPC leg. By the proposed method, the CMV of the inverter is fully eliminated, while the utilization of the DC-link voltage is not decreased at all. Furthermore, all of the DC-link and flying capacitor voltages of the inverter are well controlled. Simulation and experimental results have verified the validity of the proposed scheme.

• Journal of Microbiology
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• v.34 no.1
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• pp.74-81
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• 1996

Two secretion vectors, pUBA240 and pUB340 were constructed by using the promoter and secretory signal region of the .alpha.-amylase gene from an .alpha.-amylase hyperproducing strain, Bacillus subtilis NA64. In this secretion vector system, various restriction enzyme sites are located immediately after the proregion of the .alpha.-amylase gene for easy replacement of various foregn structural genes. To evaluate this secretion vectors, the .betha.-lactamase gene of pBR322 was used as a reporter gene. The expressed and biologically active .betha.-lactamase was secreted into the culture broth from B. subtilis LKS86 transformants harboring each .betha.-lactamase secreting plasmid, pUBAbla and pUBSble. In both cases, more than 92% of expressed .betha.- lactamases were located idn the culture medium. The amount of the secreted .betha.-lactamase was about 80% of the total secreted proteins in the culture medium.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.615-619
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• 1998

Active power filter is a kind of device used for compensating instantaneous reactive and harmonic current in three-phase circuits. An essential technology that determines the behavior of an active power filter is the method of detecting the distorted current. Using three-dimensional space vectors, this paper describes a simple method for detecting the distorted current without any coordinate transformation. The effectiveness of the novel method is verified by the theoretical analysis and simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.12
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• pp.1220-1225
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• 2010

This paper proposes a novel active noise control (ANC) approach that uses an IIR filter and neural network techniques to effectively reduce interior noise. We construct a multiple-channel IIR filter module which is a linearly augmented framework with a generic IIR model to generate a primary control signal. A three-layer perceptron neural network is employed for establishing a secondary-path model to represent air channels among noise fields. Since the IIR module and neural network are connected in series, the output of an IIR filter is transferred forward to the neural model to generate a final ANC signal. A gradient descent optimization based learning algorithm is analytically derived for the optimal selection of the ANC parameter vectors. Moreover, re-estimation of partial parameter vectors in the ANC system is proposed for online learning. Lastly, we present the results of a numerical study to test our ANC methodology with realistic interior noise measurement obtained from Korean railway trains.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1363-1371
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• 2017

In this paper, an improved Direct Power Control (DPC) algorithm is presented for grid connected three phase PWM rectifiers. The new DPC approach is based on two main tasks. First the optimization of the look-up table, which is well-known in conventional DPC, is outlined for selecting the optimum converter output voltage vectors. Secondly a very simple and effective method is used to directly calculate their duty cycles from the power errors. Therefore, the measured active and reactive powers are made to track their references using hysteresis controllers. Then two vectors are selected and applied during one control cycle to minimize both the active and reactive power ripples. The main advantages of this method are that there is no need of linear current controllers, coordinates transformations or modulators. In addition, the control strategy is able to operate at constant switching frequencies to ease the design of the power converter and the AC harmonic filter. The control exhibits a good steady state performance and improves the dynamic response without any overshoot in the line current. Theoretical principles of the proposed method are discussed. Both simulation and experimental results are presented to verify the performance and effectiveness of this control scheme.

• Journal of Power Electronics
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• v.12 no.6
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• pp.895-903
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• 2012

This paper presents a fast switching direct torque control (FS-DTC) using only a single DC-link current sensor. In FS-DTC, six new active voltage complex space vectors (CSVs) are synthesized by the conventional active voltage space vectors (SVs). The corresponding sectors are rotated in the anticlockwise direction by 30 degrees. A selection table is defined to select the CSVs. Based on the "Different Phase Mode", the output sequence of the selected CSV is optimized. Accordingly, a reconstruction method is proposed to acquire the phase currents. The core of the FS-DTC is that all of the three phase currents can be reliably reconstructed during every two sampling periods, which is the result of the fast switching between different phases. The errors between the reconstructed and actual currents are strictly limited in one sampling period. The FS-DTC has the advantages of the standard DTC scheme such as simple structure, quick torque response and robustness. As can be seen in the analysis, the FS-DTC can be thought of as an equivalent standard DTC scheme with 86.6% of the maximum speed, 173.2% of the torque ripple, and 115% of the response time of the torque. Based on a dSPACE DS1103 controller, the FS-DTC is implemented in an induction machine drive system. The results verify the effectiveness of the FS-DTC.

• The Journal of the Korea Contents Association
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• v.7 no.2
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• pp.1-10
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• 2007

In this paper, we propose a face recognition system using AAM and Gabor feature vectors. EBGM, which is prominent among face recognition algorithms employing Gabor feature vectors, requires localization of facial feature points where Gabor feature vectors are extracted. However, localization of facial feature points employed in EBGM is based on Gator jet similarity and is sensitive to initial points. Wrong localization of facial feature points affects face recognition rate. AAM is known to be successfully applied to localization of facial feature points. In this paper, we propose a facial feature point localization method which first roughly estimate facial feature points using AAM and refine facial feature points using Gabor jet similarity-based localization method with initial points set by the facial feature points estimated from AAM, and propose a face recognition system based on the proposed localization method. It is verified through experiments that the proposed face recognition system using the combined localization performs better than the conventional face recognition system using the Gabor similarity-based localization only like EBGM.