• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.9
• /
• pp.912-918
• /
• 2014

In this paper, a VHF band multi channel phase discriminator for direction finding equipment using tripple baseline interferometer technique is proposed. In order to measure simultaneously phase difference between IF(Intermediate Frequency) signals of the direction finding equipment, phase discriminator was designed to have parallel structure with multi channel, the phase correlator of phase discriminator was designed with I, Q mixer for reducing number of components. And digital LUT(Look Up Table) was applied for compensating error of phase discriminator due to phase unbalance of RF components. The measured phase accuracy of fabricated phase discriminator was 2 degree RMS(Root Mean Square) at 30 dB SNR condition, which is superior to the phase accuracy of conventional product.

• The KIPS Transactions:PartC
• /
• v.10C no.3
• /
• pp.367-376
• /
• 2003

This study deals with the DCMST (Delay constrained Capacitated Minimum Spanning Tree) problem applied in the topological design of local networks or finding several communication paths from root node. While the traditional CMST problem has only the traffic capacity constraint served by a port of root node, the DCMST problem has the additional mean delay constraint of network. The DCMST problem consists of finding a set of spanning trees to link end-nodes to the root node satisfying the traffic requirements at end-nodes and the required mean delay of network. The objective function of problem is to minimize the total link cost. This paper presents two-phased heuristic algorithm, which consists of node exchange, and node shift algorithm based on the trade-off criterions, and mean delay algorithm. Actual computational experience and performance analysis show that the proposed algorithm can produce better solution than the existing algorithm for the CMST problem to consider the mean delay constraint in terms of cost.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.25 no.4
• /
• pp.641-649
• /
• 2011

This study was purposed to evaluate the effects of root of Liriope spicata (RLS) on LPS-induced COPD (chronic obstructive pulmonary disease) model. The extract of RLS was treated to A549 cells and LPS-induced COPD mice model. Then, various parameters such as cell-based cyto-protective activity and histopathological finding were analyzed. RLS showed a protective effect on LPS-induced cytotoxicity in A549 cells. This effect was correlated with analysis for caspase 3 levels, protein level of cyclin B1, Cdc2, and phospho-Erk1/2, and gene expression of TNF-${\alpha}$ and IL-$1{\beta}$ in A549 cells. RLS treatment also revealed the protective effect on LPS-induced lung injury in COPD mice model. This effect was evidenced via histopathological finding including immunofluence stains against caspase 3, and protein level of cyclin B1, Cdc2, and Erk1/2 in lung tissue. These data suggest that RLS has a pharmaceutical properties on lung injury. This study would provide an scientific evidence for the efficacy of RLS for clinical application to patients with COPD.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.34 no.2
• /
• pp.113-120
• /
• 2021

The wave-propagation phenomenon in an infinite medium has been used to describe the physics in many fields of engineering and natural science. Analytical or numerical methods have been developed to obtain solutions to problems related to the wave-propagation phenomenon. Energy radiation into infinite regions must be accurately considered for accurate solutions to these problems; hence, various numerical and mechanical models as well as boundary conditions have been developed. This paper proposes a new boundary condition that can be applied to scalar-wave or horizontally-polarized shear-wave (or SH-wave) propagation problems in layered waveguides. A governing equation is obtained for the SH waves by applying finite-element discretization in the vertical direction of the waveguide and subsequently modified to derive the boundary condition for the infinite region of the waveguide. Using the orthogonality of the eigenmodes for the SH waves in a layered waveguide, the new boundary condition is shown to be equivalent to the existing root-finding absorbing boundary condition; further, the accuracy is shown to increase with the degree of the new boundary condition, and its stability can be proven. The accuracy and stability are then demonstrated by applying the proposed boundary condition to wave-propagation problems in layered waveguides.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.42 no.4
• /
• pp.723-730
• /
• 2017

In this paper, we consider an online compensation algorithm considering the mutual coupling and suggest a new GPS antenna array to apply. To evaluate the anti-jamming performance for the proposed antenna array, ULA and URA, we divide direction finding of multiple jamming signals into environments. 1. there is no mutual coupling. 2. there is mutual coupling but no compensation. 3. mutual coupling is compensated. RMSE analysis showed that the online compensation algorithm works and that peak detection is possible for multiple jamming signals.

• Geophysics and Geophysical Exploration
• /
• v.2 no.1
• /
• pp.54-62
• /
• 1999

This paper describes a datuming scheme for a prestack dataset which uses wavefield depth extrapolation. The formulation of the prestack datuming algorithm is performed by finding the adjoint operator to the corresponding forward prestack wavefield extrapolation from a flat surface to an irregular surface. Here I used double-square-root (DSR) equation to extrapolate wavefield in prestack sense. This correspond to the forward model of the well known `survey sinking` prestack imaging algorithm.

• Journal of the Chungcheong Mathematical Society
• /
• v.21 no.1
• /
• pp.107-116
• /
• 2008

In this study the k-fold pseudo-Cauchy's method of order k+3 is proposed from the classical Cauchy's method defined by an iteration $x_{n+1}=x_n-{\frac{f^{\prime}(x_n)}{f^{{\prime}{\prime}}(x_n)}}{\cdot}(1-{\sqrt{1-2f(x_n)f^{{\prime}{\prime}}(x_n)/f^{\prime}(x_n)^2}})$. The convergence behavior of the asymptotic error constant is investigated near the corresponding simple zero. A root-finding algorithm with the k-fold pseudo-Cauchy's method is described and computational examples have successfully confirmed the current analysis.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 1999.10a
• /
• pp.147-154
• /
• 1999

This paper presents a procedure for the frequency-domain analysis of a non-proportionally damped structure subjected to stationary seismic loads and for the finding of proper damper locations through simple analysis procedure without iteration. The shear areas of the dampers are decided in proportion to the magnitude of the components of the primary mode shape vector and to the root mean square values of the story drifts, The root-mean-squear responses are obtained using a power spectral density function for the ground acceleration. the results are compared with those obtained from damper placement decided in sequency based on the maximum story drift. According to the results the reliability of the proposed method turns out to be satisfactory compared to the methods which required iteration.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.20 no.3
• /
• pp.3-8
• /
• 2010

There are some efficient brute force algorithm for factorization. Fermat's factorization is one of the way of brute force attack. Fermat's method works best when there is factor near the square-root. This paper shows that why Fermat's method is effective and verify that there are only one answer. Because there are only one answer, we can start Fermat's factorization anywhere. Also, we convert from factorization to finding square number.

• Journal of the Korean Mathematical Society
• /
• v.59 no.6
• /
• pp.1067-1082
• /
• 2022

This paper presents a new optimal three-step eighth-order family of iterative methods for finding multiple roots of nonlinear equations. Different from the all existing optimal methods of the eighth-order, the new iterative scheme is constructed using one function and three derivative evaluations per iteration, preserving the efficiency and optimality in the sense of Kung-Traub's conjecture. Theoretical results are verified through several standard numerical test examples. The basins of attraction for several polynomials are also given to illustrate the dynamical behaviour and the obtained results show better stability compared to the recently developed optimal methods.