• Economic and Environmental Geology
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• v.39 no.4 s.179
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• pp.403-416
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• 2006

Magnetic method is rapid, cheap and simple geophysical exploration technique, and has wide range of applications such as resources prospecting, geological structure investigation and even geotechnical and environmental problems. Especially, aeromagnetics gives fundamental and useful geoscientific data fnr not only assessment of potential resources, but also national land planning. Magnetic method, perhaps the oldest geophysical technique, was relatively early introduced into Korea. Documents during Japanese occupation says that magnetic method was used for exploring metallic ore deposits and hot spring, and that a geomagnetic observatory was operated. From mid 1950's, after Korean War, magnetic explorations for natural resources such as metallic ore, uranium, coal, and groundwater were intensively executed for industrialization. Apache aeromagnetic survey project during $1958{\sim}1959$ and its ground follow-up surveys are typical and important cases in those days. Magnetic survey techniques were rapidly advanced during 1970's and 1980's with improvements of instruments, growth of geophysical manpower, and availability of computers. The national aeromagnetic mapping project by KIGAM in 1981 showed the improved technical capability of those days. Decline of mining industry since mid 1980's moved the exploration objects from traditional resources to new ones such as groundwater and geothermal resources, and applications to investigation of geological structure were revived. Recently appeared applications such as natural hazard assessment, and engineering and environmental studies increased the magnetic method's utility in the realm of exploration.

• Proceedings of the KSEG Conference
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• 2002.04a
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• pp.285-290
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• 2002

조사지역은 전라남도 함평군 함평읍으로부터 남쪽으로 엄다면 화양리, 학야리, 성천리 일대에 발달한 충적층으로서. 이 지역에는 남서-북동방향으로 광주단층이 통과하고 있는 것으로 추정된다. 충적층 하부에 발달한 단층을 포함한 대규모 파쇄대 파악에는 지표지질조사로서 한계가 있다. 따라서 이 연구에서는 물리탐사방법을 적용하여 충적층 하부의 대규모 파쇄대의 방향과 연장성을 파악하고자 하였으며, 사용된 물리탐사법은 전기비저항 2차원탐사, 전자탐사 그리고 자력탐사이다. 전기비저항 탐사결과 충적층 내에서 남북방향의 연장성을 갖는 전기비저항 이상대가 파악되었으나, 자력탐사와 전자탐사의 측정자료에는 이 이상대에대한 반응을 관찰할 수 없었다. 이는 전자탐사의 경우, 가탐심도가 매우 작은 EM31을 사용하였고, 또한 자력탐사는 주변 지질매체 간의 대자율 차이가 없는 것에 기인한 것으로 판단된다. 따라서 향후 지하심부의 탐사를 위해 전자탐사법중 TEM 탐사를 실시할 계획이며, 또한 낮은 전기비저항 이상대의 연장성을 정확히 파악하기 위하여 기 측정된 전기비저항 탐사 측선 사이를 탐사할 예정이다.

• Geophysics and Geophysical Exploration
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• v.16 no.1
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• pp.36-44
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• 2013

We conducted the airborne magnetic and radiometric survey for the characterization of the black shale related and pyrometamorphic uranium deposits distributed in Geumsan area. For the successful characterization of the uranium deposits, the general geological and structural geological features were investigated based on the lithological and linear feature analysis to individual magnetic and radiometric data as the first step. Lithological analysis from the magnetic reduction to the pole and downward continuation map revealed that prominent positive anomalies caused by black and dark gray slate member were clearly recognized as magnetic sources. These results indicate that magnetic survey, even though it is not a direct method for the detection of uranium, can be a useful tool in uranium detection. By the linear feature analysis based on 2nd vertical derivative and curvature map, two linearments corresponded the gray hornfels and black slate member were extracted and in succession, the additional uranium potential zone was inferred. Final discrimination whether uranium-rich or not was confirmed by radiometric and uranium anomaly map. From these analysis, we finally concluded that uranium deposit originated by pyrometamorphic process was confined near the intrusive area only. On the contrary, it was found that black shale related uranium deposit is distributed and extended through out the entire survey area with south-west to north-east direction. In addition, from the linear feature analysis based on radiometric total anomaly map, the typical discontinuous characteristics were recognized in areas where uranium-contained linearments cross the faults. From the above discussion, we concluded that airborne magnetic and radiometric survey are complementary to each other. So it is preferable to carry out simultaneously for the efficient data processing and fruitful interpretation.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2012.10a
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• pp.301-302
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• 2012

• Proceedings of the KSEEG Conference
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• 2007.04a
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• pp.415-417
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• 2007

• Geophysics and Geophysical Exploration
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• v.17 no.3
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• pp.147-154
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• 2014

For analyzing the distribution of chromite, magnetic survey was carried out on the chromium mineralized belt in Bophi Vum area, northwestern Myanmar. As a result, the magnetic susceptibility of chromite is lower than those of dunite and harzburgite, which are background rocks of chromite. Also, the locations of low magnetic anomaly zone and low magnetic susceptibility models of 3D magnetic inversion result are spatially well matched with those of chromite occurrences confirmed by the surface geological survey and trench survey. Some of low magnetic effects are expanded to the periphery area of chromite occurrences. Considering the magnetic susceptibility characteristics of various rocks in this area, the expanded low magnetic anomaly zones are estimated as the high potential areas bearing chromite. For confirming the potential area of chromite pointed by coarse magnetic survey, the additional detail exploration need to be carried out in future.

• Journal of the Korean earth science society
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• v.30 no.1
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• pp.49-57
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• 2009

We studied a structure of the Kunsan basin in the Yellow Sea using ship-borne magnetic data and altimetry satellite-derived gravity data provided from the Scripps institution of oceanography in 2006. The gravity data was analyzed via power spectrum analysis and gravity inversion, and the magnetic data via analytic signal technique, pseudo-gravity transformation, and its inversion. The results showed that the depth of bedrock tended to increase as we approached the center of the South Central Sag in Kunsan basin and that the maximum and minimum of its depth were estimated to be about 6-8 km and 2 km, respectively. Inaddition, the observed high anomaly of gravity and magnetism was attributed to the intrusion of igneous rock of higher density than the surrounding basement rock in the center of South Central Sag, which was consistent with the interpretation of seismic data obtained in the same region.

• Resources Recycling
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• v.10 no.3
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• pp.43-50
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• 2001

Characteristics of crushing and magnetic separation on the spent batteries, were investigated for reclaiming spent carbon-zinc and alkaline manganese dioxide batteries. Crushing of carbon zinc battery was easier than that of alkaline $MnO_2$battery using impact type crusher with rotary blades. Most of magnetic products were distributed in the range of 8 mesh size. With crushing 1 ton of spent carbon-zinc and alkaline $MnO_2$batteries respectively, magnetic separation of 8 mesh oversize particles, we can get 214 kg and 235 kg of magnetic products which is composed of 94% and 88% of Fe.

• Geophysics and Geophysical Exploration
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• v.27 no.2
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• pp.108-118
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• 2024

In this study, expressions for the magnetic field and magnetic gradient tensor due to an elliptical disk were derived. Igneous intrusions and kimberlite structures often have elliptical cylinders with axial symmetry and elliptical cross sections. An elliptical cylinder with varying cross-sectional areas was approximated using stacks of elliptical disks. The magnetic fields of elliptical disks were derived using the Poisson relation, which includes the direction of magnetization in the gravity gradient tensor, as described in a previous study (Rim, 2024). The magnetic gradient tensor due to an elliptical disk is derived by differentiating the magnetic fields, which is equivalent to obtaining ten triple-derivative functions acquired by differentiating the gravitational potential of the elliptical disk three times in each axis direction. Because it is possible to exchange the order of differentiation, the magnetic gradient tensor is derived by differentiating the gravitational potential of the elliptical disk three times, which is then converted into a complex line integral along the closed boundary curve of the elliptical disk in the complex plane. The expressions for the magnetic field and magnetic gradient tensor derived from a complex line integral in complex plane are perfectly consistent with those of the circular disk derived from the Lipschitz-Hankel integral.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.141-151
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• 2006

A blank test was done to calculatee the car itself's magnetic effect as noise and to eliminate it from the data set of total magnetic intensity(=magnetic flux density) exploration in a car-borne magnetic exploration system. To calculate the induced magnetic intensity(= magnetization) and the remanent magnetic intensity(= magnetization) of the car itself, we have installed the magnetometer on a fixed point and measured the magnetic intensity letting the car move around the magnetometer, and we have changed the data set into an analogous data set as if acquired in the condition that we have parked the car on the same fixed point and measured the magnetic intensity moving the magnetometer around the magnetometer. Through an inversion with the later data set as input, we have calculated the magnetic center and the magnetic moments of the induced magnetic intensity(= magnetization) and the remanent magnetic intensity(= magnetization) of the car itself with the two centers coincided because of some barriers of the inversion algorithm that we have used in this study. On the other hand, we have extracted the magnetic anomaly by reducing i. e. vectorially eliminating the induced magnetic intensity(= magnetization) and the remanent magnetic intensity(= magnetization) of the car itself calculated forwardly, from the magnetic exploration data set acquired by the car-borne magnetic exploration system.