• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.103-108
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• 2005

The purpose of numerical analysis is to design an effective algorithm to realize some mathematical model on computer. In general the approximate value, which is obtained from computer operation, is not the same as the real value that is given by mathematical theory. Therefore the mr estimate measuring how approximate value is near to the real value, is the most significant task to evaluate the efficiency of algorithm. The limit of an error is used for mr estimation at the most case, but the exact mr evaluation could not be expected to get for there is no way to know the real value of the given problem. Wegmann's method has been researched, which is one of the solution to derive the numerical conformal mapping. We proposed an improved method for convergency by applying a low frequency filter to the Wegmann's method. In this paper we investigate error analysis based on some mathematical theory and propose an effective method which makes us able to estimate an error if the real value is not acquired. This kind of proposed method is also proved by numerical experiment.

• Journal of Korean Institute of Industrial Engineers
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• v.15 no.1
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• pp.1-15
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• 1989

In the past few years, increasing numbers of automatic storage/retrieval system (AS/RS) using computer controlled storage/retrieval machine have been installed. This paper introduces two modeling approaches to determine the best operating policy for AS/RS : an M/G/1 queueing model and a computer simulation model. The operating policy consists of three elements. : the operation command cycle, the storage location method, and the operation dispatching rule. The analysis based on M/G/1 model is suitable for a quick and approximate evaluation, due to its inherent strict assumptions. The computer simulation can be used to perform a more realistic analysis. It is shown through the study that a significant improvement in the throughput and/or the space requirement can be expected by determining the best operating policy to a particular system. Most important, the computer simulation demonstrates its powerful capability in evaluating dynamic stochatic systems with imperfect information.

• Journal of Information Processing Systems
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• v.19 no.3
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• pp.377-384
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• 2023

The existence of abnormal breakpoint data leads to poor channel balance in wireless sensor networks (WSN). To enhance the communication quality of WSNs, a method for positioning abnormal breakpoint data in WSNs on the basis of signal reconstruction is studied. The WSN signal is collected using compressed sensing theory; the common part of the associated data set is mined by exchanging common information among the cluster head nodes, and the independent parts are updated within each cluster head node. To solve the non-convergence problem in the distributed computing, the approximate term is introduced into the optimization objective function to make the sub-optimization problem strictly convex. And the decompressed sensing signal reconstruction problem is addressed by the alternating direction multiplier method to realize the distributed signal reconstruction of WSNs. Based on the reconstructed WSN signal, the abnormal breakpoint data is located according to the characteristic information of the cross-power spectrum. The proposed method can accurately acquire and reconstruct the signal, reduce the bit error rate during signal transmission, and enhance the communication quality of the experimental object.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4057-4064
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• 2014

In this paper, attempts were made to design a preform for a final punch inexpensively using the proposed approximate optimization method or metamodel-based simulation optimization. The design objective of this work is to achieve a uniform distribution of effective strains, the angle dimension of the preformed punch is chosen as a design variable, and maximum underfill ratio is used as a constraint. For this optimization, a computer simulation of a practical punch forging process is run using DEFORM software, in which a preformed punch(workpiece), a master punch(upper die), and a bottom die are dealt with. A validation method is introduced to determine if the simulation results match the actual forging process. In addition, this work presents the detailed design optimization procedure consisting of (i) generation of an initial metamodel, (ii) metamodel optimization, (iii) validation of metamodel-predicted optimum, and (iv) metamodel improvement.

• ETRI Journal
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• v.17 no.3
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• pp.45-63
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• 1995

This paper proposes an algorithm to improve the correlation between giga-hertz transverse electromagnetic (GTEM) cell and open area test site (OATS). It is based on the dipole modeling process of an unknown source object in a GTEM cell and on the evaluation of the approximate far field equations correlated with measured GTEM powers at output port of the GTEM cell. In this algorithm, the relative phase differences between dipole moments play an important part in modeling the test object as a set of dipoles and offer stable calculation of emission values. The radiated emission test using this algorithm requires fifteen orientations of equipment under test, but the increased orientations as compared with the previous method have little effect on the time needed for testing. Radiation from a notebook computer has been tested for statistical analysis of the correlation between GTEM data and OATS data. The emission test results of the notebook computer show that the mean, the standard deviation, and the correlation coefficient are -0.62, 1.99, and +0.85, respectively. These figures indicate that this algorithm provides improved accuracy in the measurement of electromagnetic emissions over the previous method.

• Journal of applied mathematics & informatics
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• v.11 no.1_2
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• pp.59-80
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• 2003

An incomplete factorization method for preconditioning symmetric positive definite matrices is introduced to solve normal equations. The normal equations are form to solve linear least squares problems. The procedure is based on a block incomplete Cholesky factorization and a multilevel recursive strategy with an approximate Schur complement matrix formed implicitly. A diagonal perturbation strategy is implemented to enhance factorization robustness. The factors obtained are used as a preconditioner for the conjugate gradient method. Numerical experiments are used to show the robustness and efficiency of this preconditioning technique, and to compare it with two other preconditioners.

• Journal of Biomedical Engineering Research
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• v.16 no.1
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• pp.33-42
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• 1995

A new neural network architecture for the recognition of patterns from images is proposed, which is partially based on the results of physiological studies. The proposed network is composed of multi-layers and the nerve cells in each layer are connected by spatial filters which approximate receptive fields in optic nerve fields. In the proposed method, patterns recognition for complicated images is carried out using global features as well as local features such as lines and end-points. A new generating method of matched filters representing global features is proposed in this network.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.1
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• pp.7-14
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• 1983

Linear feature such as lines and curves are one of important features in image processing. In this paper, new method of linear feature detection is suggested. Also, we have studied approximation technique which transforms detected linear feature into data structure for the practical. This method is based on graph theory and principle of this method is based on minimal spanning tree concept which is widely used in edge linking process. By postprocessing, Hairs and inconsistent line segments are removed. To approximate and describe traced linear feature, piecewise linear approximation is adapted. The algorithm is demonstrated through computer simulations.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.169-172
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• 2009

In this paper, we propose the method to improving touch recognition using edge mask on a touched object at vision-based touchscreen. Because vision-based touchscreen recognizes touch using threshold simply, noise occur in fist or wrist in case of touch directly with hand, correct touch recognition was difficult. However, in this paper, we execute morphology and extract surrounding mask in object that approximate to touchscreen, use change of contrast for the mask. When we touch screen to use these dynamic information, prevent noise. The goal of this paper is when hand was touched on screen it can recognize to touch.

• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.755-766
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• 2012

A Binary Decision Diagram (BDD) is a graph-based data structure that calculates an exact top event probability (TEP). It has been a very difficult task to develop an efficient BDD algorithm that can solve a large problem since its memory consumption is very high. Recently, in order to solve a large reliability problem within limited computational resources, Jung presented an efficient method to maintain a small BDD size by a BDD truncation during a BDD calculation. In this paper, it is first identified that Jung's BDD truncation algorithm can be improved for a more practical use. Then, a more efficient truncation algorithm is proposed in this paper, which can generate truncated BDD with smaller size and approximate TEP with smaller truncation error. Empirical results showed this new algorithm uses slightly less running time and slightly more storage usage than Jung's algorithm. It was also found, that designing a truncation algorithm with ideal features for every possible fault tree is very difficult, if not impossible. The so-called ideal features of this paper would be that with the decrease of truncation limits, the size of truncated BDD converges to the size of exact BDD, but should never be larger than exact BDD.