• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.168-169
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• 2011

The aim of this paper is to present a new algorithm for the load flow problem using modified Newton-Raphson (NR) iteration method and a approach to derive a simple formula to compensate the reactive power at some heavy load bus. The reactive power source used in this research is the DG which is adjacent to the heavy load. Phenomena of low voltages may cause the load flow calculation process to diverge. In modified NR method, low voltages will be detected and corrected before the next iteration. Therefore, the results of load flow calculation process satisfy the voltage constraint i.e. higher than the lower voltage limit or higher than the critical voltage in case the conventional load flow diverges. Linearizing the power network using PTDFs is a simple method with accepted errors. A new value of voltage at the DG terminal is computed in terms of the voltage deviation of load buses. In this approach, solving the entire system is unnecessary.

• Computational Structural Engineering
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• v.3 no.3
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• pp.133-140
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• 1990

Analysis of cable structures is complex because their force - displacement relationships are highly nonlinear and also because large deformations introduce geometric nonlinearity. Therefore, we must take account their geometric nonlinearity in the analysis and find the equilibrated shape of cable structures. In this paper, to slove these problems, numerical procedures involving geometrical nonlinearity are introduced. They are applicable to general cable net, flexible transmission lines and suspended cable roof. These procedures are divided into two parts; one is to obtain the equilibrated shapes and stresses of the cable structures with uniform load by flexibility iteration method, the other is to analyse the equilibrated structures subjected to nodal external forces by nonlinear finite element method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.3
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• pp.170-176
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• 2017

In this paper, we proposed the miniaturized structure of the Log-Periodic Dipole Array(LPDA) antenna for PS-LTE(Pubic Safety-Long Term Evolution) service. The length of array dipole was shortened by adding a fractal tree element with iteration to the array dipole to miniaturize the LPDA antenna. As the result, the proposed LPDA antenna was reduced up to 25 %, compared a typical LPDA antenna. To validation of the proposed LPDA antenna specification, the proposed LPDA antenna is fabricated using aluminum with 1.5 mm thickness and performances are measured. Comparison between simulation result and experiment shows good agreement.

• Bulletin of the Korean Mathematical Society
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• v.26 no.2
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• pp.127-134
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• 1989

This paper proposes a deformation method for solving practical nonlinear programming problems. Utilizing the nonlinear parametric programming technique with Quasi-Newton method [6,7], the method solves the problem by imbedding it into a suitable one-parameter family of problems. The approach discussed in this paper was originally developed with the aim of solving a system of structural optimization problems with frequently appears in various kind of engineering design. It is assumed that we have to solve more than one structural problem of the same type. It an optimal solution of one of these problems is available, then the optimal solutions of thel other problems can be easily obtained by using this known problem and its optimal solution as the initial problem of our parametric method. The method of nonlinear programming does not generally converge to the optimal solution from an arbitrary starting point if the initial estimate is not sufficiently close to the solution. On the other hand, the deformation method described in this paper is advantageous in that it is likely to obtain the optimal solution every if the initial point is not necessarily in a small neighborhood of the solution. the Jacobian matrix of the iteration formula has the special structural features [2, 3]. Sectioon 2 describes nonlinear parametric programming problem imbeded into a one-parameter family of problems. In Section 3 the iteration formulas for one-parameter are developed. Section 4 discusses parametric approach for Quasi-Newton method and gives algorithm for finding the optimal solution.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.1-6
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• 2006

This paper predicts the stall characteristics of three-dimensional wings. An iterative decambering approach is introduced into the nonplanar lifting surface method to take into consideration the stall characteristics of wings. An iterative decambering approach uses known airfoil lift curve and moment curve to predict the stall characteristics of wings. The multi-dimensional Newton iteration is used to take into consideration the coupling between the different sections of wings. Present results are compared with experiments and other numerical results. Computed results are in good agreement with other data. This scheme can be used for any wing with the twist or control surface and for wing-wing configurations such as wing-tail configuration or canard-wing configuration.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.1
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• pp.33-39
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• 1999

In order to calculate geoidal height refered to Bessel ellipsoid, methods to translate geoidal heights from a certain coordinate system to an arbitrary system with the corresponding ellipsoid are studied. and geoidal heights refered to Bessel ellipsoid were computed from EGM96 Model refered to GRS80 using iteration method pro-posed in this paper. Transformation parameters between WGS84 and Bessel were calculated using geoidal heights computed from iteration method. The result of coordinate transformation(standard deviation) were 0.009 second in latitude and 0.006 in longitude and 0.393m in orthometric height.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.47-52
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• 2013

In this paper, The existing interference alignment algorithms were analyzed in Rayleigh fading channel environment. The interference alignment techniques are divided to two parts. First thing is Iterative-method, another is Linear-method. Iterative method needs local channel info, but it has the constraint of iteration. On the other hand Linear-method must have global channel info, but has free of iteration and better performance. This paper evaluates the performance of interference alignment algorithms in Rayleigh fading channel of outdoor environment and WLAN channel based on IEEE 802.11n of indoor environment.

• Journal of Biomedical Engineering Research
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• v.38 no.5
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• pp.219-226
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• 2017

Penalized-likelihood (PL) reconstruction methods for transmission tomography are known to provide improved image quality for reduced dose level by efficiently smoothing out noise while preserving edges. Unfortunately, however, most of the edge-preserving penalty functions used in conventional PL methods contain at least one free parameter which controls the shape of a non-quadratic penalty function to adjust the sensitivity of edge preservation. In this work, to avoid difficulties in finding a proper value of the free parameter involved in a non-quadratic penalty function, we propose a new adaptive method of space-variant smoothing with a simple quadratic penalty function. In this method, the smoothing parameter is adaptively selected for each pixel location at each iteration by using the image roughness measured by a pixel-wise standard deviation image calculated from the previous iteration. The experimental results demonstrate that our new method not only preserves edges, but also suppresses noise well in monotonic regions without requiring additional processes to select free parameters that may otherwise be included in a non-quadratic penalty function.

• East Asian mathematical journal
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• v.24 no.1
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• pp.35-43
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• 2008

Let E be a uniformly convex Banach space and K be a nonempty closed convex subset of E. Let ${\{T_i\}}^N_{i=1}$ be N nonexpansive self-mappings of K with $F\;=\;{\cap}^N_{i=1}F(T_i)\;{\neq}\;{\theta}$ (here $F(T_i)$ denotes the set of fixed points of $T_i$). Suppose that one of the mappings in ${\{T_i\}}^N_{i=1}$ is semi-compact. Let $\{{\alpha}_n\}\;{\subset}\;[{\delta},\;1-{\delta}]$ for some ${\delta}\;{\in}\;(0,\;1)$ and $\{{\beta}_n\}\;{\subset}\;[\tau,\;1]$ for some ${\tau}\;{\in}\;(0,\;1]$. For arbitrary $x_0\;{\in}\;K$, let the sequence {$x_n$} be defined iteratively by $\{{x_n\;=\;{\alpha}_nx_{n-1}\;+\;(1-{\alpha}_n)T_ny_n,\;\;\;\;\;\;\;\;\; \atop {y_n\;=\;{\beta}nx_{n-1}\;+\;(1-{\beta}_n)T_nx_n},\;{\forall}_n{\geq}1,}$, where $T_n\;=\;T_{n(modN)}$. Then {$x_n$} convergence strongly to a common fixed point of the mappings family ${\{T_i\}}^N_{i=1}$. The result presented in this paper generalized and improve the corresponding results of Chidume and Shahzad [C. E. Chidume, N. Shahzad, Strong convergence of an implicit iteration process for a finite family of nonexpansive mappings, Nonlinear Anal. 62(2005), 1149-1156] even in the case of ${\beta}_n\;{\equiv}\;1$ or N=1 are also new.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.11
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• pp.1-7
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• 2009

In this paper, a simple analytical model for deriving the threshold voltage of a short-channel intrinsic-body SDG SOI MOSFET is suggested. Using the iteration method, both Laplace equations in intrinsic silicon body and gate oxide are solved two-dimensionally. Obtained potential distributions in both regions are expressed in terms of fourth and fifth-order of the coordinate perpendicular to the silicon channel direction. Making use of them, the surface potential is obtained to derive the threshold voltage in a closed-form. Simulation results show the fairly accurate dependencies of the threshold voltage on the various device parameters and applied bias voltages.