• Journal of Broadcast Engineering
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• v.22 no.5
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• pp.579-588
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• 2017

Recently, due to the development of network environment, the internet market has been expanding, so it is necessary to standardize the data format and API to exchange information among objects. Therefore, MPEG (Moving Picture Expert Group), an international standardization organization, is establishing the MPEG-IoMT (ISO/IEC 23093) project to standardize the Internet of Things. MPEG-IoMT establishes Core Experiment (CE) and discusses overall data exchange such as data exchange procedure, markup language and communication method. In this paper, core experiments 1, 2, 4, and 5 of the core experiments of MPEG-IoMT will be discussed. The performance information of the sensor, the sensor data, the performance information of the driver, and the exchange procedure of the control command are explained and the exchange of the media additional data is discussed. We compare the markup language and communication method through experiment.

• Geophysics and Geophysical Exploration
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• v.18 no.4
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• pp.232-240
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• 2015

Magnetotelluric (MT) survey investigates electrical structure of subsurface by measuring natural electromagnetic fields on the earth surface. For the accurate interpretation of MT data, the precise three-dimensional (3-D) modeling algorithm is prerequisite. Since MT responses are affected by electrical anisotropy of medium, the modeling algorithm has to incorporate the electrical anisotropy especially when analyzing time-lapse MT data sets, for monitoring engineered geothermal system (EGS) reservoir, because changes in different-vintage MT-data sets are small. This study developed a MT modeling algorithm for the simulation MT responses in the presence of electrical anisotropy by improving a pre-existing staggered-grid finite-difference MT modeling algorithm. After verifying the developed algorithm, we analyzed the effect of vertical transversely isotropic (VTI) anisotropy on MT responses. In addition, we are planning to extend the applicability of the developed algorithm which can simulate not only the horizontal transversely isotropic (HTI) anisotropy, but also the tiled transversely isotropic (TTI) anisotropy.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.42-47
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• 2007

We have studied feasibility of the geostatistical approach to enhance the result of analysis of the sparsely obtained MT(Magnetotelluric) data by combining with gravity data. We have attempted to use geostatistics for integrating the MT data along with gravity data. To evaluate the feasibility of this approach, we have studied about interrelation between geological boundary and density distribution, and corrected density distribution for conversion to more sensitive to geological boundary by minimization of difference between z-directional variogram values of resistivity distribution obtained MT inversion and density distributions. Then, this method has been tested on model and field data. In model test, the results obtained were good agreement with real model. And in a real field data, the result of analysis demonstrate convincingly that our geostatistical approach is effective.

• Journal of the Korean earth science society
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• v.30 no.5
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• pp.550-564
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• 2009

When magnetotelluric (MT) data are obtained in the vicinity of the coast, the surrounding seas make it difficult to interpret subsurface structure, especially the deep part of the subsurface. We introduce an iterative method to correct the sea effect, based on the previous topographic correction method that removes the distortion due to topographic changes in seafloor MT data. The method first corrects the sea effect in observed MT impedance, and then inverts corrected response in a model space without the sea. Due to mutual coupling between the sea and the subsurface structure, the correction and inversion steps are iterated until the changes in each result become negligible. The method is tested for 1- and 2-D structures using synthetic MT data produced by 3-D forward modeling including surrounding seas. In all cases, the method closely recovers the true structure assumed to generate synthetic responses after a few iterations.

• Geophysics and Geophysical Exploration
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• v.11 no.4
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• pp.286-301
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• 2008

When magnetotelluric (MT) data are obtained in vicinity of the coast, the sea can distort observed MT responses, especially those of deep part of subsurface. We introduce an iterative method to correct the sea effect, based on the previous topographic correction method which removes the distortions due to topographic changes in seafloor MT data. The method first corrects the sea effect in observed MT impedance, and then inverts corrected responses in a model space without the sea. Due to mutual coupling between sea and subsurface structure, the correction and inversion steps are iterated until changes in each result become negligible. The method is validated for 1-D and 2-D structure using synthetic MT data produced by 3-D forward modeling including surrounding seas. In all cases, the method closely recovers the given structure after a few iterations. To test the applicability of the proposed method to field data, we generate synthetic MT data for the Jeju Island whose 1-D conductivity structure is well known, using 3-D forward modeling. The distortions due to the surrounding sea start to appear below the frequency about 1 Hz, and are relatively severe in the electrical field perpendicular to the coastline because of the location of the observation sites. The proposed method successfully eliminates the sea effect after three iterations, and both 1-D and 2-D inversion of corrected responses closely recover the given subsurface structure of the Jeju Island model.

• Geophysics and Geophysical Exploration
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• v.27 no.2
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• pp.129-143
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• 2024

In magnetotelluric (MT) surveys, small inhomogeneities near the surface cause a static shift in which apparent resistivities shift regardless of frequency. As the static shift in MT data leads to errors in subsurface structure interpretation, many studies have been conducted over the past few decades to mitigate or remove the distortions it caused. The most representative method involves removing static shifts from the data before inversion. Conversely, static shifts can be corrected during inversion or included in the inversion process. In addition, other geophysical data can be used to remove static shifts. However, the correction methods are limited to one-dimensional (1D) static responses, and limitations remain in two- or three-dimensional (2D or 3D) interpretation of distorted MT data owing to static shifts. This study provides a foundation for future studies on static shift by analyzing several previously published methods.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.209-214
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• 2005

In the present age, the quality of MT(magnetotellurics) data highly depends on the level of industrial interference in data. We analyzed the correlation between the spatial distributions of man-made EM noise source and the characteristics of MT data. The noise source analysis shows the correlation between the noise source density and the power spectral density of measured magnetic field in the frequency band of 60 Hz harmonics. In the MT 'dead band', the strong polarization observed on the magnetic field reveals that the severe artificial noises are caused by the adjacent metropolis.

• Geophysics and Geophysical Exploration
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• v.6 no.4
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• pp.199-206
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• 2003

Characteristics of the static shift are discussed by comparing the three-dimensional MT inversion with/without static shift parameterization. The galvanic distortion by small-scale shallow feature often leads severe distortion in inverted resistivity structures. The new inversion algorithm is applied to four numerical data sets contaminated by different amount of static shift. In real field data interpretations, we generally do not have any a-priori information about how much the data contains the static shift. In this study, we developed an algorithm for finding both Lagrangian multiplier for smoothness and the trade-off parameter for static shift, simultaneously in 3-D MT inversion. Applications of this inversion routine for the numerical data sets showed quite reasonable estimation of static shift parameters without any a-priori information. The inversion scheme is successfully applied to all the four data sets, even when the static shift does not obey the Gaussian distribution. Allowing the static shift parameters have non-zero degree of freedom to the inversion, we could get more accurate block resistivities as well as static shifts in the data. When inversion does not consider the static shift as inversion parameters (conventional MT inversion), the block resistivities on the surface are modified considerably to match possible static shift. The inhomogeneous blocks on the surface can generate the static shift at low frequencies. By those mechanisms, the conventional 3-D MT inversion can reconstruct the resistivity structures to some extent in the deeper parts even when moderate static shifts are in the data. As frequency increased, however, the galvanic distortion is not frequency independent any more, and thus the conventional inversion failed to fit the apparent resistivity and phase, especially when strong static shift is added. Even in such case, however, reasonable estimation of block resistivity as well as static shift parameters were obtained by 3-D MT inversion with static shift parameterization.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.253-258
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• 2006

The Korean peninsula has been known to be very difficult to acquire clean MT and GDS data due to its highly industrialization and civilization. In this environment, a pre-screening step selecting data segments with a proper S/N ration is an essential one. This study modified the automatic pre-screening step based on the spectral power of electromagnetic field (RMP) taking account of the situation of the Korean Peninsula. The modified RMP technique was applied to MT data measured at seven sites located in middle part of the peninsula. In the whole sense, the RMP technique considerably improved the connectivity of apparent resistivity and phase curves around the period of 10 sec. In addition, the results processed by the RMP technique showed a very little difference with those derived from manual editing, and the superior performance of it is found especially in the connectivity of apparent resistivity curve.

• Journal of Multimedia Information System
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• v.8 no.4
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• pp.301-308
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• 2021

The purpose of this study is to analyze the oral records of sports development contributors to explore the direction of big data research on sports development contributors in the future. To this end, the audio file produced in the interview with Lee00, a sports development contributor, was converted into text. The major themes were extracted by analyzing these oral records. The sub-themes were extracted in chronological order. Keywords were extracted by analyzing sub-themes. And the extracted keywords are searched in Google search engine to find related topics and to use them. A Google search for the topic 'Mt. Inwang' extracted from the oral archives of Lee00, a contributor to the development of sports, finds newspaper articles about President Moon Jae-in's climbing Mt. Inwang and opening up Mt. Bukhan. In addition, articles about Mt. Inwang and mountain climbers that the narrator In-jeong Lee speaks are searched for. Through these articles, you can Deriving the theme of the museum exhibition, Collection of museum exhibits, Use as climbing education material.