• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.215-218
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• 2007

Tunnel detection is known to be one of the challenging problems in geophysical society. Among various geophysical methods, we tried to examine the applicability of electrical resistivity tomography (ERT) method to detect empty tunnel. In this study, we analyzed the ERT data acquired at the test site for tunnel detection. The inversion results have shown reasonable image of the tunnel although the resolution is quite poor. Moreover, we could obtain the three-dimensional attitude of tunnel through 3-D ERT imaging. Therefore, we expect that ERT can make contribution to the tunnel detection problem and further research effort such as fusion of geophysical methods will provide more reliable tunnel detection capability.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1386-1388
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• 2003

This paper analyzes the advantage of the XML, and studies the simple feature object model and Geography Markup Language that proposed by the Open GIS Consortium (OGC). We discussed the means of encoding the geographical data based on XML.

• The Journal of Engineering Geology
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• v.11 no.2
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• pp.131-139
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• 2001

Until recently, limestone yield production is mainly depend on geological investigation and boring. In the study seismic and electrical method are applied to calculate the basic data of limestone yield production. the result of geophysical prospecting, the depth of bed rock is approximately 17m. And there is a slightly difference between the limestone layer boundary which is drawn by electrical prospecting method and that of geological investigation.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.491-498
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• 2004

In recent years, as an effort to grasp the leading position in the field of maritime trading, new ports and container terminals arc now under construction. Old ports are extended. At the beginning, stones were thrown down to form stone embankments, that is stone-dams, in the outer and inner boundaries of the planned reclamation-land. S.C.P(Sand Compaction Pile) works are often needed to improve the stability of stone-dams, where marine sediments arc relatively thick. Here, interests are centered on the shape of stone body. In this, drilling work won't provide a sufficient resolution. In addition, the result corresponds to only one borehole point information. Thus, the aim of this paper is to introduce an affordable technology, that is, a combined geophysical method(seismic tomography + Televiewer) enables to get the whole information about stone-dam section. The measuring and evaluating procedure is described in detail with an emphasis on dealing with the use of seismic detonator, proper borehole deployment and integrated data analysis. Examples of field experiments at Busan new port are illustrated, which will prove the benefit of combined geophysical method.

• 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.

• 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.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.12a
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• pp.53-62
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• 2007

Preliminary gas hydrate surveys were carried out From 2000 to 2004 in the East Sea. Research results showed the geophysical evidence of gas hydrate existence. In 2005, Gas Hydrate R&D Organization was established and 10 year gas hydrate development program was initiated. In the $1^{st}$ stage of the program from 2005 to 2007, 6,600 L-km 2-D seismic survey was conducted in the $1^{st}$ year 2005, and $400\;km^2$ 3D survey was conducted in the $2^{nd}$ year 2006. Acquired seismic data were processed and seismic section and 3D cube were produced. By geophysical interpretation and velocity analysis, prospective areas were mapped and candidate drilling sites were recommended. For the precise interpretation, velocity was analyzed using AVO method, and BSR signal was analyzed using deconvolution method. For the prospective area, OBS and high-resolution seismic surveys were conducted. This presentation shows the introduction and examples of the research results of the geophysical methods applied for the gas hydrate exploration in the East Sea.

• Geophysics and Geophysical Exploration
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• v.5 no.4
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• pp.291-298
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• 2002

We have developed a two-dimensional (2-D) magnetotelluric (MT) inversion algorithm, which can include topographic effects in inversion. We use the finite element method (FEM) to incorporate topography into forward calculation. Topography is implemented simply by moving nodes of rectangular elements in z-direction according to the elevation of air-earth interface. In the inversion process, we adopt a spatially variable Lagrangian multiplier algorithm in the smoothness-constrained least-squares inversion. The inversion algorithm developed in this study reconstructs subsurface resistivity structure quite well when topography variation exists. Also, it turns out to be effective in both resolution and stability from a model study and field data application.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.92-96
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• 2005

Comprehensive field surveys, including various hydrogeological and geophysical methods, were carried out to appraise the applicability of those methods to a leakage problem at the Sandong earth fill dam in southwestern Korea. The methods applied in the fold site were tracer tests, monitoring of drawdown and leakage with discharge of reservoir water, electrical resistivity surveys using the dipole-dipole array, self-potential (SP), and temperature logging methods. The leakage pattern in the reservoir wall was demonstrated by hydrogeological methods and was further clarified by the geophysical surveys. Leakage turned out to be through the right abutment of the reservoir wall. In this study, we conformed that the electrical resistivity method is effective in detecting the zones favorable to leakage, and SP methods are useful for delineating the leakage pathways themselves, because leaks generate strong streaming-potential anomalies.

• Geophysics and Geophysical Exploration
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• v.21 no.4
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• pp.244-254
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• 2018

The first geophysical technique applied to the agricultural sector in Korea was electrical resistivity sounding and conducted in purpose of groundwater exploitation in the 1970s. According to the diversity of agricultural activities since the 1990s, various geophysical methods including electrical resistivity, electromagnetic induction, and self-potential method were applied to several agricultural fields such as soil characterization with saline concentration in vast reclaimed area, delineation of seawater intrusion regions in costal aquifer, safety inspection of embankment dikes with leakage problem, detection of ground subsidence from overpumping and tracing of groundwater aquifer contamination by leachate from livestock mortality burial or waste burial site. This paper introduces representative geophysical techniques that have been utilized in various agricultural fields and suggests several ways to develop the geophysical methods required for the precision agriculture field in the near future based on the past achievements.