• Journal of the Korean Geophysical Society
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• v.5 no.1
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• pp.29-39
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• 2002

Geophysical data sets from the Chojeong area in the Chungbok-Do are compositely studied in terms of multi-attribute interpretations for the subsurface mappings of shallow fracture zones, associated with groundwater reservoir. Utilizing a GIS software, the attribute data were implemented to a database; a lineament from the satellite image, electrical resistivities and its standard deviation, radioactivity, seismic velocity, and bedrock depth. In an attempt to interpret 1-D electrical sounding data in 3-D views, 1-D data are firstly performed horizontal and vertical inter- and extrapolation. Reconstruction of a resistivity volume is found to be an effective scheme for subsurface mapping of shallow fracture zones. Shallow fracture zones are located in the southeastern part of the study area, which are commonly correlated with the various exploration data.

• Geophysics and Geophysical Exploration
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• v.27 no.1
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• pp.57-68
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• 2024

Offshore wind power is increasingly regarded as a viable solution for reducing greenhous emissions due to the construction of wind farms and their superior power generation efficiency. Submarine power cables play a crucial role in transmitting the electricity generated offshore to land. To monitor cables and identify points of failure, analyzing the location or depth of burial of submarine cables is necessary. This study reviewed the technology and research for detecting submarine power cables, which were categorized into seismic/acoustic, electromagnetic, and magnetic exploration. Seismic/acoustic waves are primarily used for detecting submarine power cables by installing equipment on ships. Electromagnetic and magnetic exploration detects cables by installing equipment on unmanned underwater vehicles, including autonomous underwater vehicles (AUV) and remotely operated vihicles (ROV). This study serves as a foundational resource in the field of submarine power cable detection.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.1
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• pp.27-40
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• 2013

This study is about development of technology system for an advanced deep-sea unmanned underwater robot of S. Korea analysed by the application of scenario planning. It was developed a 6000m class next-generation deep-sea unmanned underwater vehicle(or robot, UUV) system, soonly ROV 'Hemire' and Depressor 'Henuvy' in 2006 at S. Korea and motion control, adaptive control algolithm, a work-space manipulator control algolithm, especially the underwater inertial-acoustic navigation system robust to initial errors and sensor failures. But there are remained matters on position tracking of the USBL, inertial-acoustic navigation system, attitude sensor, designed sonar sensors. So this study suggest the new idea for settle the matters and then this idea help the development of the underwater inertial-acoustic navigation system robust to initial errors and sensor failures, such as acoustic signal drop-out, by modifying the error covariance of the failed sonar signal when drop-out occurs. As a result, the future policy for deep-sea unmanned underwater robot of S. Korea is to further spur the development of new technology and more improvement of the technology level for deep-sea unmanned underwater robot system with indicator and imaginary wall as external device.

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.168.2-168.2
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• 2009

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.317-331
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• 2005

[ ${\circ}$ ] 지반 분포 상환 파악 : 도모그래피 기법 ${\circ}$ 지반의 불연속면 파악 : BHTV, BIPS 및 TSP ${\circ}$ 지반의 횡파 속도 파악, 내진 설계: 표면파 기법, 다운홀 및 크로스홀 ${\circ}$ 시추공의 심도 별 원위치 물성 산출: 밀도 검층, Suspension PS 검충

• The Korean Journal of Petroleum Geology
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• v.12 no.1
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• pp.14-19
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• 2006

The electromagnetic (light) waves have a limitation to penetrate media, ie, water and sea-bottom layers, due to high energy attenuation, but acoustic (sound) waves play as the good messenger to gather the underwater target information. Therefore, the acoustic methods are applied to almost all of ocean equipments and technology in terms of in-water and sub-bottom surveys. Generally the sound character is controlled by its frequency. In case that the sound source is low frequency, the penetration is high and the resolution is low. On the other hand, its character is reversed at the high frequency. The common character at the both of light and sound is the energy damping according to the travel distance increase.

• 한국지구물리탐사학회:학술대회논문집
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• 1999.08a
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• pp.21-36
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• 1999

Recently resistivity survey is widely used for site investigations in the field of civil engineering. Since such application area requires accurate interpretation tools especially in the area of complicated geology and rough terrain topography, we developed a three-dimensional (3-D) resistivity inversion code, which can reconstruct real earth structures. Furthermore, the inversion code gives resolution-enhanced images by applying the ACB(Active Constraint Balancing) method. With the help of this inversion code, 3-D resistivity survey is now used as new techniques for site investigations in civil engineering problem. By imaging the 3-D resistivity distribution, we could get useful informations such as depth distribution of basement rock, distribution of weak zone, fractures and cavities which is crucial to civil engineers.

• The Journal of Engineering Geology
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• v.5 no.3
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• pp.259-276
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• 1995

Electrical soundings and profilings were conducted for mapping the leachate in the region of Nanji - Do Landfill site. The results of electrical surveys conducted in the landfill area show that the basal leachate is formed at the height about 30 m above the mean sea level and that there is abundant floating leachate over the basal leachate. The surveys conducted around the landfill reveal that the groundwater which may be contaminated by the leachate from the landfill flows to the Han River. The top of the basement rock in this area has been severely affected by polluted groundwater. The layer which is thoroughly saturated with leachate in this region has the very low resistivity value below 10 ohm - m and this low resistivity value indicates that the groundwater and geology are severely contaminated by the leachate and wastes of the landfill.

• Journal of the Korean Geotechnical Society
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• v.34 no.11
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• pp.93-105
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• 2018

Precise investigation and interpretation of the ground subsidence risk factors needed to predict and evaluate the settlement problems of the surrounding ground due to the ground excavation. There are various geophysical exploration methods to investigate the ground subsidence risk factors. However, there are factors that influence the characteristics of the underground medium in these geophysical methods, and the actual soil contains complex factors affecting geophysical exploration. Therefore, it is necessary to analyze the effects on the geophysical methods based on the understanding of the geotechnical properties of soil. In this study, a test bed was constructed to consider various complicated factors in the complex ground and the ground behavior was analyzed by numerical analysis. In addition, we analyzed the limitations on investigating the ground subsidence risk factors through ground penetration radar (GPR) survey. As a result, ground subsidence of Open-cut Type Excavation is caused by various factors. Especially, in the case of soft ground condition, it was found that it was greatly influenced by the flow change of groundwater level. At the center frequency of GPR of 250 MHz, the attenuation of the electromagnetic wave is severely attenuated in the clay with high electrical conductivity, making it difficult to penetrate deeply into the ground (4 m below the surface). As the electromagnetic waves pass through the groundwater level below the groundwater, the attenuation of the electromagnetic waves becomes severe.

• Journal of the Korean Geotechnical Society
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• v.24 no.10
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• pp.33-43
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• 2008

In this study, for the purpose of evaluating the shear wave velocity in core zone, cross-hole test, down-hole test, MASW (Multi-channel Analysis of Surface Wave), and seismic reflection survey were carried out on the crest of the existing 'Y' dam. The results of field tests were compared one another. Furthermore, the field test results were compared with the result by the Sawada's empirical recommendation method. The purpose of this study is to compare the results of four kinds of field tests for evaluation of shear wave velocity in core zone of existing dam, to verify applicability of the empirical method which was recommended by Sawada and Takahashi, and to recommend a reasonable method for evaluation of shear wave velocity which is needed to evaluate tile maximum shear modulus of core zone. From the results of four kinds of field tests such as cross-hole test, down-hole test, MASW, and seismic reflection survey, it was found that the shear wave velocity distributions were similar within 18 m in depth and the results obtained by MASW and seismic reflection survey were almost the same by 30 m in depth. For evaluation of shear wave velocity in core zone of the existing dam, in consideration that it is not easy to bore the hole ill the core zone of existing dam, surface surveys such as MASW and seismic reflection method are recommended as realistic methods. On condition that it is impossible to conduct the field test and it is preliminary investigation, it is recommended that Sawada's low bound empirical equation be used.