• Spatial Information Research
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• v.17 no.1
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• pp.89-102
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• 2009

The information of ocean topology is the fundamental source which is necessary for understanding the ocean, producing nautical charts and delimiting maritime boundaries. An echo sounder is being used generally to collect undersea bathymetric data, but an indirect method such as geophysical data acquired by satellites is being used recently. In this study, the outputs of ocean surveying for the production of the Basic Maps of the Sea in 1996 and 1997 in the East Sea and the bathymetric data produced by geophysical data are compared and analyzed. The study areas are Ulleung Plateau, Ulleung Basin and the southern area of Ulleung Basin which have different geophysical characteristics. Through this study, we found that the bathymetric data acquired by an indirect method using satellite is similar to the field surveying results in general configuration of ocean floor and average depth. However, the minimum square error is about 100m in 1700m depth, and it has been observed a local error up to 1000m. In addition, it has been found that the detailed undulation of ocean topology is shown on the gravity data which is acquired by the research vessel.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.305-312
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• 2017

The most effective way to distinguish subsurface interfaces that produce various geophysical responses is through the integration of multiple geophysical methods, with each method detecting both a complementary and unique set of distinct physical properties relating to the subsurface. In this study, shallow seismic reflection (SSR) and ground penetrating radar (GPR) surveys were conducted at the Cheongju-Gadeok site of the Korea National Groundwater Monitoring Network to map the water table, which was measured at 12 m depth during the geophysical surveys. The water table proved to be a good target reflector in both datasets, as the abrupt transition from the overlying unsaturated weathered rock to the underlying saturated weathered rock yielded large acoustic impedance and dielectric constant contrasts. The two datasets were depth converted and integrated into a single section, with the SSR and GPR surveys conducted to ensure subsurface imaging at approximately the same wavelength. The GPR data provided detailed information on the upper ~15 m of the section, whereas the SSR data imaged structures at depths of 10-45 m. The integrated section thus captured the full depth coverage of the sandy clay, water table, weathered rock, soft rock, and hard rock structures, which correlated well with local drillcore and water table observations. Incorporation of these two geophysical datasets yielded a synthetic section that resembled a simplified aquifer model, with the best-fitting seismic velocity, dielectric constant, and porosity of the saturated weathered layer being $v_{seismic}=1000m/s$, ${\varepsilon}_r=16$, and ${\phi}=0.32$, respectively.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.21-26
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• 2003

The visualization of three dimensional geophysical data is forcing a revolution in the way of working, and allowing the discovery and production of hydrocarbons at much lower costs than previously thought possible. There are many aspects of this revolution that are behind the scenes, such as the database structure, the storage and retrieval of data, and the exchange of data among programs. Also the user had changes where the interpreter (or manager, or processor) actually looks at and somehow interacts with the data. The use of opacity in volume rendering, and how its judicious application can assist in imaging geologic features in three dimensional seismic data. This revolutionary development of new technology is based on the philosophy of synergy of inter-disciplines of the oil industry. Group interaction fostered by large room visualization environments enables the integration of disciplines we strive for, by putting the petrophysicist, geologist, geophysicist, and reservoir engineer in one place, looking at one image together, without jargon or geography separating them. All these tools developed in the oil industry can be applied into the civil engineering industry also such as the prior geological and geophysical survey of the constructions. Many examples will show how three dimensional geophysical technology might make a revolution in the oil business industry now and in future. This change can be considered as a fusion process at data, information, and knowledge levels.

• Korean Journal of Remote Sensing
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• v.21 no.5
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• pp.371-382
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• 2005

We present a processing system for the Atmospheric Infrared Sounder (AIRS) sounding suite onboard Aqua satellite. With its unprecedented 2378 channels in IR bands, AIRS aims at achieving the sounding accuracy of radiosonde (1 K in 1-km layer for temperature and $10\%$ in 2-km layer for humidity). The core of the processor is the International MODIS/AIRS Processing Package (IMAPP) that performs the geometric and radiometric correction for generation of Level 1 brightness temperature and Level 2 geophysical parameters retrieval. The processor can produce automatically from received raw data to Level 2 geophysical parameters. As we process the direct-broadcast data almost for the first time among the AIRS direct-broadcast community, a special attention is paid to understand and verify the Level 2 products. This processor includes sub-systems, that is, the near real time validation system which made the comparison results with in-situ measurement data, and standard digital information system which carry out the data format conversion into GRIdded Binary II (GRIB II) standard format to promote active data communication between meteorological societies. This processing system is planned to encourage the application of geophysical parameters observed by AIRS to research the aqua cycle in the Korean peninsula.

• Geophysics and Geophysical Exploration
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• v.14 no.4
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• pp.335-341
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• 2011

Most sensing and instrumentation systems should have very higher sampling rate than required data rate not to miss important information. This means that the system can be inefficient in some cases. This paper introduces two new research areas about information acquisition with high accuracy from less number of sampled data. One is Compressed Sensing technology (which obtains original information with as little samples as possible) and the other is Super-Resolution technology (which gains very high-resolution information from restrictively sampled data). This paper explains fundamental theories and reconstruction algorithms of compressed sensing technology and describes several applications to geophysical exploration. In addition, this paper explains the fundamentals of super-resolution technology and introduces recent research results and its applications, e.g. FRI (Finite Rate of Innovation) and LIMS (Least-squares based Iterative Multipath Super-resolution). In conclusion, this paper discusses how these technologies can be used in geophysical exploration systems.

• Journal of the Korean earth science society
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• v.31 no.7
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• pp.681-690
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• 2010

Inversion result of geophysical data given as a block type was geostatistically simulated with borehole observation given as a point type and was applied to the rock classifying map. The geophysical data generally involved secondary information for the target material and were obtained for overall region. In contrast, borehole data provided direct information for the target material, but tended to be effective only for a narrow range of region and were dealt as a point type. Integrated simulation or kriging interpolation of these two different kinds of information required the covariance for point-point, point-block and block-block. Using the Bssim module included in SGeMS software, integrated result of geophysical data and borehole data were obtained. The results were then compared with the method of geostatistical inversion proposed by authors. Downscaling method used in this study showed relatively more flexible than the geostatistical inversion.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.24 no.1
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• pp.1-10
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• 1996

A detailed bathymetric map is used to construct a morphotectonic map of the Ulleung Basin. The definition of "morphotectonics" and the procedure of the morphotectonic mapping are described in detail. The morphotectonic structural elements of various orders and ranks are also determined using echo-sounding and other geophysical data. Preliminary analysis shows that the newly determined morpho-structural elements coincide with the locations of deeper tectonic features established by the geophysical evidences of the inner sedimentary and/or crustal sections. Therefore, the tectonic zone of the Ulleung Basin has imprinted the patterns of the inherited evolution since Neogene.e Neogene.

• Journal of the Korean Geophysical Society
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• v.3 no.3
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• pp.161-174
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• 2000

Bayesian inversion is a stable approach to infer the subsurface structure with the limited data from geophysical explorations. In geophysical inverse process, due to the finite and discrete characteristics of field data and modeling process, some uncertainties are inherent and therefore probabilistic approach to the geophysical inversion is required. Bayesian framework provides theoretical base for the confidency and uncertainty analysis for the inference. However, most of the Bayesian inversion require the integration process of high dimension, so massive calculations like a Monte Carlo integration is demanded to solve it. This method, though, seemed suitable to apply to the geophysical problems which have the characteristics of highly non-linearity, we are faced to meet the promptness and convenience in field process. In this study, by the Gaussian approximation for the observed data and a priori information, fast Bayesian inversion scheme is developed and applied to the model problem with electric well logging and dipole-dipole resistivity data. Each covariance matrices are induced by geostatistical method and optimization technique resulted in maximum a posteriori information. Especially a priori information is evaluated by the cross-validation technique. And the uncertainty analysis was performed to interpret the resistivity structure by simulation of a posteriori covariance matrix.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.231-236
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• 2002

The understanding of underground geologic structures is of great importance for the surface and subsurface constructions, prevention of natural hazards such as land-slides and subsidence, and many other areas. To get the information on the geologic conditions, many of investigations such as geologic survey, geophysical explorations, testings on the physical properties of rocks, drilling tests and logging, and groundwater surveys are usually conducted, and tremendous data are collected accordingly. In general, however, these huge amount of data are interpreted in the individual areas only. If these data are analyzed collectively, much more information on the geologic conditions can be obtained. In this study, 3D visualization of borehole logging data is attempted. Borehole logging data are obtained at the urban subsidence area. To compare the 3D logging data with other geologic and geophysical data such as resistivity tomography data, interface module was developed. The 3D visualization of logging data and the comparison with other data can be helpful for the understanding of underground geologic structures.

• The Journal of Engineering Geology
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• v.10 no.2
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• pp.172-188
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• 2000

This paper presents the state of art and the role of geophysical exploration techniques with evaluating the trend of domestic and worldwide seawater intrusion research, and illustrates advanced techniques obtained through the project of 'Development of the techniques for estimation, prediction, and prevention of seawater intrusion' funded by the Ministry of Science and Technology of Korea. The advanced geophysical interpretation was achieved by adding the digital geophysical logging data. DC resistivity and TEM monitorings were applied to determine whether or not the seawater intrusion was in progress. Induced Polarization technique using electric current monitoring channel was introduced to discriminate seawater contaminated zone from highly conductive layer caused by clay minerals. A conceptual model was suggested with spatial visualization of the study area to predict the diffusion of seawater contamination. Finally, the future work of the development of geophysical techniques was suggested with the base of the present level of them.