• Geophysics and Geophysical Exploration
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• v.27 no.1
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• pp.69-83
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• 2024

Considering importance and specificity, site investigations for deep geological disposal of Spent Nuclear Fuel require stringent quality control, unlike general geotechnical investigations for tunnels and bridges. In this study, we present a case of selecting geophysical survey method for individual site investigation stage and preparing geophysical survey guideline. The proposed geophysical survey guidelines include procedures, considerations, and quality control for exploration planning, data acquisition, data processing, and interpretation. They comprehensively summarize the contents of airborne electromagnetic survey and seismic reflection survey.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.497-498
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• 2021

현대사회의 산업 현장에서 기계가 사람들을 대체하면서 작업의 효율을 높이고 있다. 많은 산업 분야에서 사람들을 기계로 대체하고 있는데, 재해 및 사고 현장이나 위험 지역 조사 등에 대한 탐사 활동은 대부분 인력이 차지하고 있으며, 탐사 활동에 참여하는 많은 인력들은 2차, 3차 사고에 쉽게 노출되어 있으며, 그로 인한 인력소모가 심하다. 따라서 우리는 인력 투입 전 사고 및 재난 현장이나 위험 지역에 인력을 투입하기 전 피해를 최소화 하면서 탐사 인력에 대한 안전이 보장된 근무 환경을 개선 시키기 위해서 무인 탐사차량을 생각하게 되었다. 무인 탐사 차량에는 아두이노와 라즈베리파이를 메인으로 삼았고, 현장의 온도와 습도, 화재여부, 가스여부를 측정하기 위한 센서들은 아두이노에 연결하고, 카메라와 라이다센서의 경우 라즈베리파이에 연결을 하였다. 그리고 모든 데이터값은 블루투스와 와이파이 모듈을 통해서 수신받을 수 있게 프로그램을 구성하였다.

• Geophysics and Geophysical Exploration
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• v.18 no.4
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• pp.216-222
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• 2015

Airborne transient electromagnetic (ATEM) surveying was introduced several decades ago in the mining industry to detect shallow conductive targets. However, conventional ATEM systems have limited depth of investigation because of weak signal strength. Recently, the grounded electrical source airborne transient electromagnetic (GREATEM) system was proposed to increase the depth of investigation. The GREATEM is a semi-airborne transient electromagnetic system because a long grounded wire is used as the transmitter. Traditionally, ATEM sounding data have been interpreted with 1D earth models to save the computing time because modern ATEM systems generally collect large data sets. However, the GREATEM 1D modeling requires numerical integration along the wire, so it takes much more time than the 1D modeling of conventional ATEM. In this study, the adaptive Born forward mapping (ABFM) was applied to the ATEM 1D modeling because the ABFM is incommensurably faster than the ordinary GREATEM 1D modeling. Comparing the results from ordinary and ABFM 1D modeling, it was confirmed that the ABFM can be applied to the 1D modeling of GEATEM.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.489-490
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• 2021

본 연구에서는 해양사고 처리 중 발생하는 인명사고 발생률을 감소시키고, 효율적으로 양식장을 관리하는 것을 전제로 카메라와 센서를 다기능 해양탐사 로봇에 적용하고자 한다. 현재의 양식장 관리 시스템은 수온 체크만 할 수 있게 되어있다. 이러한 시스템은 양식어에게 적합한 환경을 제공해주기 쉽지 않다. 본 논문은 이러한 문제점들을 개선하기 위해 기존의 해양 처리시스템과 양식 시스템 대신 카메라와 수온 센서, pH 농도 센서, 초음파 거리 센서, DC 모터, 블루투스 모듈을 적용한 다기능 해양탐사 로봇 기술을 제안한다. 기존의 시스템과는 다르게 안전하고 효율적으로 환경을 분석하고, 제어할 수 있다.

• Geophysics and Geophysical Exploration
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• v.12 no.1
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• pp.1-7
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• 2009

Airborne electromagnetics (AEM) is a useful tool for investigating volcanic structures because it can survey large and inaccessible areas. Disadvantages include lower accuracy and limited depth of investigation. The Grounded Electrical Source Airborne Transient Electromagnetic(GREATEM)survey system was developed to increase the depth of investigation possible using AEM. The method was tested in a survey at Mount Bandai in north-eastern Japan. Mount Bandai is an andesitic stratovolcano that rises 1819m above sea level. An eruption in July 1888 left a hoof-shaped collapsed wall in its northern crater and avalanche debris at its base. Previous surveys of Mount Bandai allow for comparisons of data on its structure and collapse mechanism as obtained by GREATEM and other geophysical methods. The results show resistive structures in recent volcanic cones and conductive structures in the collapsed-crater area. Conductive areas around the collapsed wall correspond to an alteration zone resulting from hydrothermal activity, supporting the contention that a major cause of the collapse associated with the 1888 eruption was hydrothermal alteration that structurally weakened the interior of the volcanic edifice.

• Geophysics and Geophysical Exploration
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• v.20 no.1
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• pp.33-42
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• 2017

Recently, the grounded electrical-source airborne transient electromagnetic (GREATEM) system with high power source was introduced to achieve deeper investigation depth and to overcome high noise level. Although the GREATEM is a transient electromagnetic system using a long grounded wire as the transmitter, GREATEM data have been interpreted with 1D earth models because 2D or 3D modeling and inversion of vast airborne data are complicated and expensive to calculate. Generally, 1D inversion is subsequently applied to every survey point and combining 1D images together forms the stitched conductivity-depth image. However, the stitched models often result in abrupt variations in neighboring models. To overcome this problem, laterally constrained inversion (LCI) has been developed in inversion of ATEM data, which can yield layered sections with lateral smooth transitions. In this study, we analysed the GREATEM data through 1D numerical modeling for a curved grounded wire source. Furthermore, we developed a laterally constrained inversion scheme for continuous GREATEM data based on a layered earth model. All 1D data sets and models are inverted as one system, producing layered sections with lateral smooth transitions. Applying the developed LCI technique to the GREATEM data, it was confirmed that the laterally constrained inversion can provide laterally smooth model sections that reflect the layering of the survey area effectively.

• Geophysics and Geophysical Exploration
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• v.21 no.3
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• pp.150-161
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• 2018

Recently, unmanned aircraft EM (electromagnetic) survey based on ICT (Information and Communication Technology) has been widely utilized because of the efficiency in regional survey. We performed the theoretical study on the unmanned airship EM system developed by KIGAM (Korea Institute of Geoscience and Mineral resources) as part of the practical application of unmanned aircraft EM survey. Since this system has different configurations of transmitting and receiving loops compared to the conventional aircraft EM systems, a new technique is required for the appropriate interpretation of measured responses. Therefore, we proposed a method to calculate the EM field for the arbitrary shaped transmitter and verified its validity through the comparison with analytic solution for circular loop. In addition, to simulate the magnetic responses by three-dimensionally (3D) distributed anomalies, we have adapted our algorithm to 3D frequency-domain EM modeling algorithm based on the edge-FEM (finite element method). Though the analysis on magnetic field responses from a subsurface anomaly, it was found that the response decreases as the depth of the anomaly increases or the flight altitude increases. Also, it was confirmed that the response became smaller as the resistivity of the anomaly increases. However, a nonlinear trend of the out-of-phase component is shown depending on the depth of the anomaly and the used frequency, that makes it difficult to apply simple analysis based on the mapping of the magnitude of the responses and can cause the non-uniqueness problem in calculating the apparent resistivity. Thus, it is a prerequisite to analyze the appropriate frequency band and flight altitude considering the purpose of the survey and the site conditions when conducting a survey using the unmanned aircraft EM system.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.01a
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• pp.185-186
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• 2021

기존의 건물 점검은 사람이 직접 들어가 확인하는 방식이 일반적이다. 본 연구에서는 건물 탐사를 보다 안전하고 신속하게 하는 것을 전제로 하여 현재 상용화 되고 있는 드론과 아두이노를 이용한 센서를 적용하고자 한다. 건물 점검은 사람이 직접 들어가 확인하는 만큼 안전 수칙을 지켜가며 실시해야 하지만, 불편함이나 귀찮음을 핑계로 지켜지지 않는 경우가 대다수이다. 지켜지지 못한 안전 수칙에 더불어, 건물의 직접적인 상태를 미리 알지 못하고 진입하게 됨으로 발생하는 인명피해는 불가피하다. 본 논문은 이러한 문제점들을 개선하기 위해 기존의 어려운 조작의 드론에 호버링이 가능하게 하는 옵티컬 플로어 센서를 장착하여 조작을 보다 쉽게 하고 아두이노의 센서를 적용한 '건물 탐사 드론' 기술을 제안한다. 기존의 드론과 다르게 카메라와 센서를 이용해 건물의 점검을 대신하고, 센서들의 값을 앱으로 전송받아 핸드폰으로 받아 볼 수 있다.

• Geophysics and Geophysical Exploration
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• v.10 no.1
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• pp.77-88
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• 2007

Following a successful bathymetric mapping demonstration in a previous study, the potential of airborne EM for seafloor characterisation has been investigated. The sediment thickness inferred from 1D inversion of helicopter-borne time-domain electromagnetic (TEM) data has been compared with estimates based on marine seismic studies. Generally, the two estimates of sediment thickness, and hence depth to resistive bedrock, were in reasonable agreement when the seawater was ${\sim}20\;m$ deep and the sediment was less than ${\sim}40\;m$ thick. Inversion of noisy synthetic data showed that recovered models closely resemble the true models, even when the starting model is dissimilar to the true model, in keeping with the uniqueness theorem for EM soundings. The standard deviations associated with shallow seawater depths inferred from noisy synthetic data are about ${\pm}5\;%$ of depth, comparable with the errors of approximately ${\pm}1\;m$ arising during inversion of real data. The corresponding uncertainty in depth-to-bedrock estimates, based on synthetic data inversion, is of order of ${\pm}10\;%$. The mean inverted depths of both seawater and sediment inferred from noisy synthetic data are accurate to ${\sim}1\;m$, illustrating the improvement in accuracy resulting from stacking. It is concluded that a carefully calibrated airborne TEM system has potential for surveying sediment thickness and bedrock topography, and for characterising seafloor resistivity in shallow coastal waters.

• The Science & Technology
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• v.9 no.8 s.87
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• pp.23-27
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• 1976

우리나라에서 본격적으로 물리탐사를 시도한것은 1958~1960년에 실시한 항공자력탐사로서 그후 현재까지 불과 20년이 지나지 않았다. 그간 물리탐사의 기술발전으로 자원탐사분야에 많은 공헌이 있었다. 현재까지 주로 적용된 분야는 철자원탐사를 위한 자력탐사, 지하수조사를 위한 전기비저항탐사동, 연등의 통화금속광물탐사를 위한 각종 전기탐사, 제3기층 지질구조와 땜공사, 공업단지조성등의 기반암조사, 그리고 광산의 갱내 출수조사등을 위한 탄성파탐사, 우라늄자원을 위한 방사능탐사, 그리고 해저지질 및 자원조사를 위한 해상물리탐사등이다. 이와 동시에 석탄층조사를 위한 전기탐사 및 Model연구자력탐사의 전산처리 적용, 그리고 광물 및 암석의 물리적 성질등 학술분야에 대한 기초연구도 계속하여 왔다. 우리나라에 있어 물리탐사의 적용조건은 비교적 험악한 지형, 복잡한 지질구조, 광상의 불규칙 또는 소규모의 발달과 산재등이다. 이와 같은 특징은 탐사해석의 정도를 높이기 위하여 보다 고도의 과학기술문제의 해결을 요구하고 있으며 이와 동시에 현대적 탐사방법과 연구개발로 대상자원의 탐사지역확대와 지하심부 탐사등이 당면과제이다. 기술과제로서는 석탄 및 기타자원에 대한 물리검층탐사, 경상계 지질구조구명을 위한 탄성파탐사 및 동력탐사의 적용, 항공자력, 전자 및 방사능탐사 및 해양의 각종물리탐사의 기술개발이 있으며 그외 탐사자료의 전산처리기술 및 지구과학의 기초연구등이 있다.