• Journal of Power System Engineering
• /
• v.17 no.1
• /
• pp.50-57
• /
• 2013

This describes the formulation for the free vibration of joined conical-cylindrical shells with uniform thickness using the transfer of influence coefficient. This method was developed based on successive transmission of dynamic influence coefficients, which were defined as the relationships between the displacement and the force vectors at arbitrary nodal circles of the system. The two edges of the shell having arbitrary boundary conditions are supported by several elastic springs with meridional/axial, circumferential, radial and rotational stiffness, respectively. The governing equations of vibration of a conical shell, including a cylindrical shell, are written as a coupled set of first order differential equations by using the transfer matrix of the shell. Once the transfer matrix of a single component has been determined, the entire structure matrix is obtained by the product of each component matrix and the joining matrix. The natural frequencies and the modes of vibration were calculated numerically for joined conical-cylindrical shells. The validity of the present method is demonstrated through simple numerical examples, and through comparison with the results of previous researchers.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.7
• /
• pp.1307-1311
• /
• 2006

In this paper, we propose new speech feature parameter using the Matrix Factorization for appearance part-based features of speech spectrum. The proposed parameter represents effective dimensional reduced data from multi-dimensional feature data through matrix factorization procedure under all of the matrix elements are the non-negative constraint. Reduced feature data presents p art-based features of input data. We verify about usefulness of NMF(Non-Negative Matrix Factorization) algorithm for speech feature extraction applying feature parameter that is got using NMF in Mel-scaled filter bank output. According to recognition experiment results, we confirm that proposed feature parameter is superior to MFCC(Mel-Frequency Cepstral Coefficient) in recognition performance that is used generally.

• Honam Mathematical Journal
• /
• v.35 no.3
• /
• pp.417-433
• /
• 2013

We consider the iterative solution of a quadratic matrix equation with special coefficient matrices which arises in the quasibirth and death problem. In this paper, we show that the elementwise minimal positive solvent of the quadratic matrix equations can be obtained using Newton's method if there exists a positive solvent and the convergence rate of the Newton iteration is quadratic if the Fr$\acute{e}$chet derivative at the elementwise minimal positive solvent is nonsingular. Although the Fr$\acute{e}$chet derivative is singular, the convergence rate is at least linear. Numerical experiments of the convergence rate are given.

• Composites Research
• /
• v.16 no.6
• /
• pp.33-40
• /
• 2003

The initial thermal degradation of polymer matrix composite is not observed easily. At the beginning of thermal degradation of polymer matrix composites, phase transformation such as chain scission, oxidation occur, and then micro delamination is produced in matrix and interface between matrix and fiber before blistering. Initial heat damage deteriorate mechanical properties of composites. We presented the detection method of the initial heat damage of composites conveniently using ultrasonic technique. Absorption coefficient and material velocity was measured with thermal degradation and degree of cure. The more thermal degradation was progressed, the more absorption coefficient was increased. When the cure temperature is more high, the absorption coefficient of cured composite is increased and material velocity is decreased. We concluded that cure temperature is more high, the defects such as void is increased and molecular structure cured at high temperature has cross-linking structure which is more absorb the ultrasonic waves.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.6
• /
• pp.171-177
• /
• 2002

Metal matrix composites had generated a lot of interest in recent times because of significant in specific properties, it was also highlighted as the material of frontier industry because strength, heat-resistant, corrosion-resistant and wear-resistant were superiored. In recent years, the study of metal matrix composite has increased by aluminum alloy. The study is based on the tribological properties of AC4CH that is a part of the mechanical property of metal matrix composites. Metal matrix composite that is produced from matrix material AC4CH and reinforcement SiO$_2$, Al$_2$O$_3$ and TiO$_2$ are added to the metal matrix composite fur strength so binding among the whisker can take place. Each metal matrix composite is produced using the squeeze casting method. To test for tribe a pin-on-disk machine and lubricant is used without paraffine 8.2CST at room temperature which is 40$\^{C}$. As the results of this study, the tribological properties of each specimen are more improved than AC4CH. The variation of coefficient resistance is more stable at the AC4CH and TiO$_2$, but the variation rates are higher at the inanimate binder.

• Journal of Ubiquitous Convergence Technology
• /
• v.2 no.1
• /
• pp.18-26
• /
• 2008

The invariance relation existing in the non-negative matrix factorization (NMF) is used for constructing robust image hashes in this work. The image is first re-scaled to a fixed size. Low-pass filtering is performed on the luminance component of the re-sized image to produce a normalized matrix. Entries in the normalized matrix are pseudo-randomly re-arranged under the control of a secret key to generate a secondary image. Non-negative matrix factorization is then performed on the secondary image. As the relation between most pairs of adjacent entries in the NMF's coefficient matrix is basically invariant to ordinary image processing, a coarse quantization scheme is devised to compress the extracted features contained in the coefficient matrix. The obtained binary elements are used to form the image hash after being scrambled based on another key. Similarity between hashes is measured by the Hamming distance. Experimental results show that the proposed scheme is robust against perceptually acceptable modifications to the image such as Gaussian filtering, moderate noise contamination, JPEG compression, re-scaling, and watermark embedding. Hashes of different images have very low collision probability. Tampering to local image areas can be detected by comparing the Hamming distance with a predetermined threshold, indicating the usefulness of the technique in digital forensics.

• Journal of the Korean Statistical Society
• /
• v.23 no.1
• /
• pp.167-178
• /
• 1994

To estimate coefficient matrix in autoregressive model, usually ordinary least squares estimator or unconditional maximum likelihood estimator is used. It is unknown that for univariate AR(p) model, unconditional maximum likelihood estimator gives better power property that ordinary least squares estimator in testing for unit root with mean estimated. When autoregressive model contains multiple unit roots and unconditional likelihood function is used to estimate coefficient matrix, the seperation of nonstationary part and stationary part of the eigen-values in the estimated coefficient matrix in the limit is developed. This asymptotic property may give an idea to test for multiple unit roots.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.12A
• /
• pp.1346-1353
• /
• 2007

In this paper, the methods are presented for the calculation of general coupling coefficient matrixes used in the band pass filter design. They are calculated from transmission coefficient($S_{21}$) and reflection coefficient($S_{11}$) with desired characteristics derived from the poles of filter function and return loss(RL). The calculated matrixes from this method are transformed to the folded canonical filter structure using similarity transformation which lends us the practical filter design. Based on the resulting matrix, the folded canonical filter has been designed.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.31B no.8
• /
• pp.147-159
• /
• 1994

The performance of the improvement method of spatial resolution for satellite images based on the generalized inverse matrix is superior to the conventional methods. But, this method calculates the coefficient values for extracting the spatial information from the relation between a small pixel and large pixels. Accordingly it has the problem of remaining the blocky patterns at the result image. In this paper, a new generalized inverse matrix method is proposed which is different in the calculation method of coefficient values for extracting the spatial information. In this proposed metod, it calculates the coefficient values for extracting the spatial information from the relation between a small pixel and small pixels. Consequently it can improve the spatial resolution more efficiently without remaining the blocky patterns at the result image. The effectiveness of the proposed method is varified by simulation experiments with real TM image data.

• Structural Engineering and Mechanics
• /
• v.29 no.5
• /
• pp.531-550
• /
• 2008

This paper adopts the numerical assembly method (NAM) to determine the exact solutions of natural frequencies and mode shapes of a multi-span and multi-step beam carrying a number of various concentrated elements including point masses, rotary inertias, linear springs, rotational springs and springmass systems. First, the coefficient matrix for an intermediate station with various concentrated elements, cross-section change and/or pinned support and the ones for the left-end and right-end supports of a beam are derived. Next, the overall coefficient matrix for the entire beam is obtained using the numerical assembly technique of the conventional finite element method (FEM). Finally, the exact solutions for the natural frequencies of the vibrating system are determined by equating the determinant of the last overall coefficient matrix to zero and the associated mode shapes are obtained by substituting the corresponding values of integration constants into the associated eigenfunctions.