• Journal of the Korean Society for Nondestructive Testing
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• v.10 no.1
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• pp.84-90
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• 1990

By discriminating the wave propagation paths in cylindrical vessels, a technique for AE source location has been proposed. This method is based on the path difference between several propagating directions from a source to a sensor. One sensor can receive multiple waveforms sequentially including a direct arrival and several others propagated through the circumferential direction. An wave front normally propagates in all directions and as many waveforms can reach the sensor until the signal faded out by attenuation. Only the first four arrivals suffice the condition for calculating the source location. The proposed method was examined for an actual cylindrical vessel by the source location experiment using simulated AE sources. The test showed very promising results and the method can be utilized for a simple AE source location without multi-channel instruments.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.1
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• pp.5-9
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• 2003

The waveforms of partial discharges (PDs) imply physical and structural properties of PD sources, so analyzing them give us information on the kind of PD sources and the location. Waveforms of PD as a time series function have variable amplitudes but sustain a certain uniform shape, which shows well the characteristics of the waveforms and frequency region. They can also be used as parameters having time and frequency information of PD signals and applied to classification of multiple PDs sources via Artificial Neural Network with back propagation (BP) learning.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.513-515
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• 2000

This paper deals with a method for determining an optimal operation strategy of dispersed generating sources considering thermal merits. The optimal operation of these sources can be determined by the principle of equal incremental fuel cost. This paper presents an optimal operation strategy using the Kuhn-Tucker's optimal conditions and also an priority method to decide the optimal location of those sources in power systems. The validity of the proposed algorithms are demonstrated using a model system.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.155-163
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• 2012

The geometrical and electrical errors of array sensors can severely degrade the performance of array sensor system. Various calibration techniques are developed to alleviate this problem. In this paper, two different calibration methods with respect to location, gain and phase of array sensors are presented. One method applies the first-order Taylor series expansion to approximate the true steering vector from the nominal values of array sensors. Then a set of equations is formed by using the null characteristics of the MUSIC spectrum to estimate errors of location, gain and phase of array sensors. Another method estimates these errors based on the data covariance matrix of pilot sources. From the simulations, it is demonstrated that two calibration algorithms calibrated an array system successfully. In addition to that, Fistas and Manikas's algorithm is more robust against noise than Ng and Lie's one when SNR is from 10dB to 50dB.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.758-763
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• 1994

The work discusses the problems of modelling of the process of acoustic signal generation in machines. We have pointed out that in the task of minimizing of both moise and vibration, the key problem is identification of sources and paths of propagation, both in terms of their location and of definition of their characteristic features. Properly conducted identification makes possible the use of relatively simple mathematical models and this fact is particularly important for a broad application of the proposed methods in practice.

• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.323-328
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• 2004

In this paper we review the observational results on Relic radio sources in clusters of galaxies. We discuss their observational properties, structures and radio spectra. We will show that Relics can be divided according to their size, morphology, and location in the galaxy cluster. These differences could be related to physical properties of Relic sources. The comparison with cluster conditions suggests that Relics could be related to shock waves originated by cluster mergers.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.158-159
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• 2005

The paper presents a method for location of subsurface UXOs. The approach utilities gradient interpretation techniques (analytic signal, horizontal gradient and Euler methods) to locate the objects. Then, linear least-squares technique, we obtain the magnetization location of the sources. We demonstrate the practical utility of the method using marine magnetic field data.

• Journal of Navigation and Port Research
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• v.33 no.4
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• pp.271-275
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• 2009

A strategic decision making on location selection for product transportation includes many tangible and untangible factors. To choose the best locations is a difficult job in the sense that objectives usually conflict with each other. In this paper, we consider a multi stage multi criteria transshipment problem with different types of items to be transported from the sources to the destination points. For the optimization of the problem, a goal programming formulation will be presented in which the location selection for each product type will be determined under the multi objective criteria. In the study, we generalize the transshipment model with a variety of product types and finite number of different intermediate nodes between origins and destinations. For the selection of the criteria we selected the costs(fixed cost and transportation cost), location numbers, and unsatisfied demand for each type of products in multi stage transportation, which are the main goals in transshipment modelling problems. The related conditions are also modelled through linear formats.

• Journal of Advanced Navigation Technology
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• v.26 no.2
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• pp.78-84
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• 2022

In this paper, we propose a closed-form based 3D localization method in the presence of multiple signal sources. General localization methods such as TDOA, AOA, and FDOA can estimate a location when a single signal source exists. When there are multiple unknown signal sources, there is a limit in estimating the location. The proposed method calculates a cross-correlation vector of signals received by sensors having an array antenna, and estimates TDOA and AOA values from the cross-correlation values. Then, the coordinate transformation is performed using the position of the reference sensor. Then, the coordinate rotation is performed using the estimated AOA value for the transformed coordinates, and then the three-dimensional position of each emitter is estimated. The proposed method verifies its performance through computer simulation.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.1
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• pp.43-53
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• 2019

In the Geumho River, 4-nitrophenol has been detected, thus it is necessary to investigate the contamination sources in order to prevent the release of this compound. However, the research to estimate the potential source is regarded as complicated research. In this study, the distributions of 4-nitrophenol were simulated and the contribution of the potential sources was estimated using a numerical model(HydroGeoSphere; HGS) and the measuring data of 4-nitrophenol from 2013 to 2017. The altitude data, the land cover data, the flow rates of the tributaries and wastewater treatment plants, and the decay rate of 4-nitrophenol was used as the input data. The results of this research showed that the contribution rates of potential contamination sources in the upstream area were higher than that of the downstream area. Most of the upstream area is the agricultural area, it seemed that 4-nitrophenol was originated from the pesticides. In order to achieve more specific location of sources, an intensive investigation in the upstream is required.