• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6C
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• pp.570-576
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• 2005

Recognition of posed face is one of the most challenging problems in the field of face recognition. In this paper, as a preprocessing step for recognizing such faces, a method to transform non-frontal face images into frontal face images is proposed. The linear relationship between eigenfaces is utilized to obtain a pose transform matrix. The proposed method is verified with a well-known face recognition algorithm based on PCA/LDA. Compared to the conventional algorithm applied to the original posed face images, our experimental results indicated that the proposed method contributes to improve the recognition rate of such faces by $20\%$.

• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.173-180
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• 2008

In this paper, we proposed an algorithm for an effective public key and private key generation to implement a secure asymmetric watermarking system against the public key attack. The public key and private key generation is based on the linear transformation using a special matrix and the keys are designed to be able to have high correlation value. We also proposed a counter plan of public key attack. This method uses a multiple public key generation and distribution. As the results, the correlation value between the public key and the private key is high in the watermarked image. After the public key attack. this can detect the correlation by using other public key.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.6
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• pp.568-572
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• 2006

This paper presents the device of recognizing image of the studded paving blocks, transmitting, the information by vibration to a visually handicapped person. Usually the blind uses the walking stick to recognize the studded paving block. This research uses a PCA (Principal Component Analysis) based image processing approach for recognizing the paving blocks. We classify the studded paving blocks into 5 classes, that is, vertical line block, right-declined line block, left-declined line block, dotted block and flat block. The 8 images for each of 5 classes are captured for each block by 112*120 pixels, then the eigenvectors are obtained in magnitude order of eigenvectors by using principal component analysis. The principal components for images can be calculated using projection of transformation matrix composed of eigenvectors. The classification has been executed using Euclidean's distance, so the block having minimum distance with a image is chosen as matched one. The result of classification is transmitted to the blind by electric vibration signals with different magnitudes and frequencies.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.3
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• pp.76-87
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• 1993

We present a self-consistent, 2-dimensional solution of the Poisson and Sch rodinger equation based on the finite difference method with a nonuniform mesh size for a AlGaAs/GaInAs/GaAs HEMT devide. During the interative self-consistent calculation, however, we calculate Schrodinger equation only a some region of device, not a fully region in order to save the moemory and the speed-up of computation, and then use the approximated data for the other region using by a interpolation method with a given values. Also we adopt the proper matrix transformation method that allows preservation of the symmetric, form of the discretized Schrodinger equation, even with the use of a nonumiform mesh size, therefor, can reduce the computation time. We calculate the wavefunction, eigenstates and the electron concentration uat channel layer nder the thermal equilibrium and the biased conditions, respectively. Also,these parameters are used to solve 2-dimensional tdistribution of potential in he entire region of device. It is proved that the method is very efficient in finding eigenstages extending over relatively large spatial area without loss of accuracy. So, it can be used rather easily in any sarbitrary modulation doped utucture.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.892-897
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• 2001

Variations of dielectric and piezoelectric properties and associated phase transformation of <001> -oriented rhombohedral 0.92Pb (Zn$\sub$1/3/Nb$\sub$2/3/)O$_3$-0.08PbTiO$_3$ single crystals were investigated. The longitudinal strain level was found to abruptly increase at 15 kV/cm, corresponding to that where an induced phase appears within a multidomain matrix. Drastic decreases in the dielectric constant, transverse coupling, and transverse piezoelectric coefficient associated with the E-field induced phase were the result of increased crystal anisotropy in PZN-PT crystals. By contrast, the thickness coupling increased from 53 % at 0 kV/cm to 64 % at 45 kV/cm, also associated with this phase transition under the E-field. The measured dielectric and piezflelectric properties found for the induced phase state were nearly identical to those of <001> poled tetragonal (1-x)PZN-xPT (x>0.1) crystals. Based on these results, it is evident that the symmetry of induced phase is tetragonal.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1283-1289
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• 2014

The state transition matrix are obtained by solving state equations in terms of Laplace inverse transformation and Cayley-Hamilton theorem, and an establishment of a precise discrete-iterative mapping of the voltage-fed buck-boost converter operating in discontinuous conduction mode is made. On the basis of the mapping, the converter bifurcation diagrams and Lyapunov exponent diagrams with the input voltage, the resistance, the inductance and the capacitance as the bifurcation parameters are obtained, and the effect of the parameters on the system stability is deeply studied. The results obtained show that they have a great influence on the stability of the system, and the general trend is that the increase of either the voltage-fed coefficient, input voltage or the load resistance, or the decrease of the filtering inductance, capacitance will make the system stability become poorer, and that all the parameters have a critical value, and when they are greater or less than the values, the system will go through stable 1T orbits, stable 2T orbits, 4T orbits, 8T orbits and eventually approaches chaos.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1217-1228
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• 2014

A method for faulted line detection of four parallel lines on the same tower is presented, based on four-summing and double-differential sequences of one terminal current. Four-summing and double-differential sequences of fault current can be calculated using a certain transformation matrix for parameter decoupling of four parallel transmission lines. According to fault boundary conditions, the amplitude and phase characteristics of four-summing and double-differential sequences of fault current is studied under conditions of different types of fault. Through the analysis of the relationship of terminal current and fault current, a novel methodology for fault line detection of four parallel transmission line on the same tower is put forward, which can pick out the fault lines no matter the fault occurs in single line or cross double lines. Simulation results validate that the methodology is correct and reliable under conditions of different load currents, transient resistances and fault locations.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1935-1944
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• 2018

With the increase of the production of energy from renewable, it becomes important to look at techniques to store this energy. Therefore, a single winding bearingless flywheel motor (SWBFM) specially for flywheel energy storage system is introduced. For the control system of SWBFM, coupling between the torque and the suspension subsystems exists inevitably. It is necessary to build a reasonable radial force mathematical model to precisely control SWBFM. However, SWBFM has twelve independently controlled windings which leads to high-order matrix transformation and complex differential calculation in the process of mathematical modeling based on virtual displacement method. In this frame, a Maxwell tensor modeling method which is no need the detailed derivation and complex theoretical computation is present. Moreover, it possesses advantages of universality, accuracy, and directness. The fringing magnetic path is improved from straight and circular lines to elliptical line and the rationality of elliptical line is verified by virtual displacement theory according to electromagnetic torque characteristics. A correction function is taken to increase the model accuracy based on finite element analysis. Simulation and experimental results show that the control system of SWBFM with radial force mathematical model based on Maxwell tensor method is feasible and has high precision.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.1
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• pp.52-60
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• 1999

This paper deals with a fault detection and isolation scheme for a DC motor driven centrifugal pump system. The emphasis is placed on the design and implementation of the residual generatorm, based on parity relation, that provides decision logic unit with residuals that will be further processed to detect and isolate three important faults in the system;brush fault, impeller fault, and the speed sensor fault. Two process faults are modelled as multiplicative type faults, while the sensor fault as an additive one. With multiplicative fault, the implementation of the residual generator needs the time varying transformation matrix that must be computed on-line. Typical implementation methods lack in generality because only a numerical approximation around the assumed fault levels is employed. In this paper, a new implementation method using well tranined neural network is proposed to improve the generality of the residual generator. Application results show that the fault detection and isolation scheme with the proposed residual generator effectively isolates three major faults in the centrifugal pump system even with a wide range of fault magnitude.

• Journal of Korea Foundry Society
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• v.9 no.6
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• pp.463-473
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• 1989

This study is aimed to investigate the effect of cyclic heat treatment which is special heat treatment on the strength and toughness in Multi-phase(Ferrite-Bainite-Martensite) Ductile cast Irons. Spceimens were austenitized at eutectoid transformation temperature range(${\alpha}+{\gamma}$) for 30min and austempered at $300^{\circ}C$ and $400^{\circ}C$ for different holding times, and then quenched in ice water to obtain the multi-phase(Ferrite-Bainite-Martensite) structure from various prior structures, which was obtained by various cyclic heat treatments. As the number of cycle in cyclic heat treatment increased, volume fraction of pearlite increased and the its morphology was refined. As the number of cycle in cyclic heat treatment increased, the multi-phase(Ferrite-Bainite-Martensite) was dispersed in whole matrix as refined island phase. Particularly, martensite among the multi-phase gradually became a spherical shape. Good combination in impact energy and tensile strength was detained in $840^{\circ}C-300^{\circ}C-15min$ condition after 10 cycles in cyclic heat treatment, and its multi-phase volume fraction is Ferrite(50%)-Martensite(l3%)-Bainite(37%).