• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.131-134
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• 2004

This paper has been studied a ADI-FDTD(Alternating Direction Implicit Finite Difference Time Domain ) algorithm using an alternating Direction time-stepping scheme for GPR( Ground-Penetrating Radar ) system simulation. We did the numerical formulations for three-dimensional ADI-FDTD algorithm and PML(Perfect Matched Layer), and made an simple experiment on a arbitrary cube with programed algorithms. And then we compared its computed results with those of conventional FDTD.

• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.55-62
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• 2012

Humanitarian demining is very important issue not only in mine affected courtiers but also for the courtiers which are technically, politically and financially supporting the mine affected courtiers. In order to achieve higher efficiency of the mine clearance operation, new technologies can significantly contribute to the societies. Since 2002, Tohoku University, Japan has developed a sensor system "ALIS" for humanitarian demining. ALIS is a hand-held dual sensor, which combines an electromagnetic induction sensor (EMI) and a Ground Penetrating Radar (GPR). ALIS has a real-time sensor tracking system based on a CCD camera and which enables the image reconstruction. We have tested ALIS in Cambodia and found that it can eliminate more than 70 % metal fragments. Since 2009, 2 sets of ALIS have detected more than 80 anti-personnel mines, and cleared more than 137,000 $m^2$ in Cambodia.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06c
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• pp.427-431
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• 2007

차세대 지뢰탐지 기술로는 NQR(Nuclear Quadrupole Resonance, 핵4중극자공명), GPR(Ground Penetrating Radar, 지상 침투 레이더)등 이 연구 및 개발 중 이다. 현재 우리나라에서도 이중 GPR을 차세대 지뢰탐지 기술로 연구중에 있다. 그렇지만 지금까지 개발된 GPR 기술을 적용한 지뢰탐지기는 얻어진 2차원 영상에 대해서 육안에 의한 식별만이 가능하여 지뢰 식별이 장시간 소요된다는 단점을 가지고 있다. 이에 본 논문에서는 그러한 문제를 해결하기 위해 주성분 분석법을 적용하여 해결하고, 제안된 시스템이 가능한지 확인하기 위해 유사한 실험 환경을 구성하고, 얻어진 영상을 학습시켜 실제로 얻어진 영상에 대한 분류가 가능한지를 확인하였다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.429-432
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• 2005

Geophysical investigations, as a non-invasive method, were conducted at the former gas station site contaminated with fuel hydrocarbons. GPR (Ground Penetrating Radar) survey was performed to locate buried objects such as USTs (Underground Storage Tanks) and fuel pipes which might serve as a origin of the site contamination. Additional GPR investigation and a resistivity survey were conducted to map water table and to characterize shallow geologic structures of the site. The results of the study have shown that seven USTs including one unknown UST and buried fuel pipes are present, and that the groundwater elevation varies with topography from approximately 1.5 to 3m below the surface and the water table is located in the residual soils above the bedrock in the site. The results also show that the geophysical methods can be a very useful tool for the characterization of the contaminated site.

• Geophysics and Geophysical Exploration
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• v.7 no.4
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• pp.256-261
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• 2004

This study grafts geophysics on modem archaeology and approaches with scientific and systematic methods to an excavation plan or archaeological study by means of GPR exploration which can assist archaeologists to study Wolseong fortress without excavating it. We investigated the areas in front of Seokbinggo (ice storage facility built of stone) and in the eastern corner of the castle with GPR. As a result, we detected 7 large squared building foundations, stone walls, an entrance for the fortress, many other foundation stones, a road and a garden.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.113-118
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• 2008

Among the geophysical methods, Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT) comprise the most promising techniques in resolving buried archaeological structures in urban territories. In this work, two case studies which involve an integrated geophysical survey employing the surface three dimensional (3D) ERT and GPR techniques, in order to archaeologically characterize the investigated areas, are presented. Totally more than 4000 square meters were investigated from the test field sites, which are located at the centre of two of the most populated cities of the island of Crete, in Greece. The ERT and the GPR data were collected along dense and parallel profiles. The subsurface resistivity structure was reconstructed by processing the apparent resistivity data with a 3D inversion algorithm. The GPR sections were processed with a systematic way applying specific filters to the data in order to enhance their information context. Finally, horizontal depth slices representing the 3D variation of the physical properties were created and the geophysical anomalies were interpreted in terms of possible archaeological structures. The subsequent excavations in one of the sites verified the geophysical results, enhancing the applicability of ERT and GPR techniques in the archaeological exploration of urban territories.

• The Journal of Engineering Geology
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• v.23 no.3
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• pp.201-216
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• 2013

Ground penetrating radar (GPR) surveys were conducted in a sand tank model in a laboratory and at an alluvial field site to detect the groundwater table and to investigate the influence of saturation on GPR response in the unsaturated zone. In the sand tank model, the groundwater table and saturation in the sand layer were altered by injecting water, which was then drained by a valve inserted into the bottom of the tank. GPR vertical reflection profile (VRP) data were obtained in the sand tank model for rising and lowering of the groundwater table to estimate the groundwater table and saturation. Results of the lab-scale model provide information on the sensitivity of GPR signals to changes in the water content and in the groundwater table. GPR wave velocities in the vadose zone are controlled mainly by variations in water content (increased travel time is interpreted as an increase in saturation). At the field site, VRP data were collected to a depth of 220 m to estimate the groundwater table at an alluvial site near the Nakdong river at Iryong-ri, Haman-gun, South Korea. Results of the field survey indicate that under saturated conditions, the first reflector of the GPR is indicative of the capillary fringe and not the actual groundwater table. To measure the groundwater table more accurately, we performed a GPR survey using the common mid-point (CMP) method in the vicinity of well-3, and sunk a well to check the groundwater table. The resultant CMP data revealed reflective events from the capillary fringe and groundwater table showing hyperbolic patterns. The normal moveout correction was applied to evaluate the velocity of the GPR, which improved the accuracy of saturation and groundwater table information at depth. The GPR results show that the saturation information, including the groundwater table, is useful in assessing the hydrogeologic properties of the vadose zone in the field.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.980-986
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• 2004

So far systematic and reliable methods for the investigation of track substructure (ballast and subgrade) are not developed yet. This study presents the applicability of GPR (Ground Penetrating Radar) and PBS (Portable Ballast Sampler) to the evaluation of railway trackbed conditions. Including FWD (Falling Weight Deflectometer) often used to evaluate the subsurface conditions of pavement, the standard system for assessing trackbed conditions will be developed in the future.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.6
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• pp.404-404
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• 2000

The receiving responses of a bistatic GPR system are analyzed by using three-dimensional FDTD method and equivalent network model. The conventional delta-gap feed model may be inaccurate because of neglecting the impedance matching characteristics between the antenna and the transmission line. In this paper, the feed model is improved by considering the physical characteristics of the actual GPR. The actually received voltage is calculated by employing the equivalent network model in angular frequency-domain, which is composed by using the results of three-dimensional FDTD analysis for an actual bistatic GPR system. The validity of the presented model is assured by showing the convergence of the computed results to the measured data.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.6
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• pp.44-53
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• 2000

The receiving responses of a bistatic GPR system are analyzed by using three-dimensional FDTD method and equivalent network model. The conventional delta-gap feed model may be inaccurate because of neglecting the impedance matching characteristics between the antenna and the transmission line. In this paper, the feed model is improved by considering the physical characteristics of the actual GPR. The actually received voltage is calculated by employing the equivalent network model in angular frequency-domain, which is composed by using the results of three-dimensional FDTD analysis for an actual bistatic GPR system. The validity of the presented model is assured by showing the convergence of the computed results to the measured data.