• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.481-488
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• 1994

In this paper a study of neuro-pathway estimation based on visual and somatosensory evoked potential is given. The evoked potentials which are caused by visual and somatosensory stimulation are detected by an average method. The forward problem that is estimating a scalp potential from a given electrical source in the brain is solved by using a triple concentric spherical shell model of the head and a single current dipole model of the neuron activity. The inverse problem which calculates a source position is solved by a least square fit between the model predicted potential and a given evoked potential measurement. The similarities between estimated sensory neuro-pathways and physiological brain function regions are verified.

• Journal of Ocean Engineering and Technology
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• v.17 no.5 s.54
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• pp.19-24
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• 2003

The question of wave source identification in a wave maker problem is the primary objective of the this paper. With the observed wave elevation, the existence of the wave maker velocity is discussed with the help of the mathematical theory of inverse problems. Utilizing the property of the Strum-Liouville system and compactness, the uniqueness and the ill-posedness(in the sense of stability) for the identification are proved.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.57-58
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• 2014

Digital filter is very important role in signal processing system. In general, input signal is determined by transfer function of the digital filter. But if input signal was exposured in various sound environment, it is difficult to verify its original source. In this paper, inverse problem in order to extract original input signal from noisy environment is considered.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.125-129
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• 2003

The identification of location and strength distribution of extended noise sources is important in the practical noise control engineering, especially in the viewpoint of dealing with the inherent nature of noise problem in question. For noise source ranking inside an automotive vehicle, the window method has been mainly used due to its simplicity. However, time and cost drawbacks in the measurement and inaccuracy due to low-frequency tunneling and lack of phase information have been a serious problem in using this method. In this study, the inverse FRF method was employed to carry out the noise source ranking inside an automotive vehicle and it was also used to predict the interior sound pressure with the change of sound insulation materials. As a result, it was found that the source contribution of vehicle panels could be successfully identified in comparison with the window method. The sound pressure at driver's ear position was predicted based on the obtained data and was compared with the measured data. The agreement in spectral trends was acceptable and their difference in level was within 3㏈ above 500㎐.

• Journal of Radiation Protection and Research
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• v.42 no.4
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• pp.212-221
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• 2017

Background: This study aims to calculate detector positions as a design of a radioactive source localizing radiation portal monitor (RPM) system using an improved genetic algorithm. Materials and Methods: To calculate of detector positions for a source localizing RPM system optimization problem is defined. To solve the problem, a modified iterative genetic algorithm (MIGA) is developed. In general, a genetic algorithm (GA) finds a globally optimal solution with a high probability, but it is not perfect at all times. To increase the probability to find globally optimal solution rather, a MIGA is designed by supplementing the iteration, competition, and verification with GA. For an optimization problem that is defined to find detector positions that maximizes differences of detector signals, a localization method is derived by modifying the inverse radiation transport model, and realistic parameter information is suggested. Results and Discussion: To compare the MIGA and GA, both algorithms are implemented in a MATLAB environment. The performance of the GA and MIGA and that of the procedures supplemented in the MIGA are analyzed by computer simulations. The results show that the iteration, competition, and verification procedures help to search for globally optimal solutions. Further, the MIGA is more robust against falling into local minima and finds a more reliably optimal result than the GA. Conclusion: The positions of the detectors on an RPM for radioactive source localization are optimized using the MIGA. To increase the contrast of the measurements from each detector, a relationship between the source and the detectors is derived by modifying the inverse transport model. Realistic parameters are utilized for accurate simulations. Furthermore, the MIGA is developed to achieve a reliable solution. By utilizing results of this study, an RPM for radioactive source localization has been designed and will be fabricated soon.

• Journal of Korea Multimedia Society
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• v.22 no.6
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• pp.684-694
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• 2019

Information spread in networks is universal in many real-world phenomena such as propagation of infectious diseases, diffusion of a new technology, computer virus/spam infection in the internet, and tweeting and retweeting of popular topics. The problem of finding the information source is to pick out the true source if information spread. It is of practical importance because harmful diffusion can be mitigated or even blocked e.g., by vaccinating human or installing security updates. This problem has been much studied, where it has been shown that the detection probability cannot be beyond 31% even for regular trees if the number of infected nodes is sufficiently large. In this paper, we study the impact of an anti-information spreading on the original information source detection. We consider an active defender in the network who spreads the anti-information against to the original information simultaneously and propose an inverse Voronoi partition based inference approach, called Voronoi Inference to find the source. We perform various simulations for the proposed method and obtain the detection probability that outperforms to the existing prior work.

• The Journal of the Acoustical Society of Korea
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• v.31 no.5
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• pp.332-339
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• 2012

Beamspace transform algorithm transforms spatial-domain data - such as x, y, z dimension - into incidence-angle-domain data, which is called beamspace-domain data. The beamspace transform method is generally used in source localization and tracking, and adaptive beamforming problem. When the beamspace transform method is used in multichannel audio source separation, the inverse beamspace transform is also important because the source image have to be reconstructed. This paper studies the beamspace transform and inverse transform algorithms for multichannel audio source separation system, especially for the beamspace-domain multichannel NMF algorithm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.150-158
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• 2003

In the beam pattern synthesis problem using line source, the relationship between source distribution function and beam pattern may be represented by Fourier transform pair. In this paper, a general method to synthesize the line source distribution for a desired lobe-like beam pattern is presented by developing the nonlinear inversion method based on an iterative sampling technique. This method can be applied to the synthesis of continuously distributed dielectric constants satisfying the desired inverse scattering coefficient patterns when illuminating by TE-polarized and TM-polarized plane waves to arbitrary dielectric material. Furthermore this method can also be applied to the synthesis of transmission line with arbitrary reflection coefficient patterns. Some bandstop spatial filter and dispersive transmission line filter are illustrated for generality.

• Industrial Engineering and Management Systems
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• v.11 no.2
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• pp.183-187
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• 2012

In this paper, we study the fixed charge transportation problem with uncertain variables. The fixed charge transportation problem has two kinds of costs: direct cost and fixed charge. The direct cost is the cost associated with each source-destination pair, and the fixed charge occurs when the transportation activity takes place in the corresponding source-destination pair. The uncertain fixed charge transportation problem is modeled on the basis of uncertainty theory. According to inverse uncertainty distribution, the model can be transformed into a deterministic form. Finally, in order to solve the uncertain fixed charge transportation problem, a numerical example is given to show the application of the model and algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.2
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• pp.291-301
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• 1999

A method for the synthesis of one-dimensional nonlinear distribution function is presented for the desired inverse scattering pattern. This method is based on the inverse transform of the solution of the Riccati equation derived from one-dimensional inverse scattering problem. Since the solution is analogous to the array factor or normalized space factor in collinear array antenna, the synthesis method for field pattern is applied for the construction of the involved line-source nonlinear distribution function. The suggested method is carried out under the optimization process, and is numerically verified by synthesizing the dispersive transmission line profile within the specified frequency band and control of scattered field on resistive strip.