• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.2
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• pp.97-102
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• 2004

The objective of this survey is to characterize personal magnetic field exposure of the general population in Korea. Participants for the survey on magnetic field exposure were selected randomly in some occupations. Those wore the magnetic field meter for about 25∼28 hours and the measured data were stored in the meter. In this first step survey, the number of participant is 244 and for the second step, about 400 participants will be surveyed in the near future. The statistics of the 24-hour exposure data are the major concern of this survey. However the survey provided the opportunity to analyze exposures corresponding to different types of activities. It was analyzed by separating periods of time corresponding to the following activities: entire 24-hour period, in bed, at work and by occupation. Therefore the database will be able to be established to analyze the status of personal magnetic field exposure and safety.

• KIEE International Transactions on Electrophysics and Applications
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• v.12C no.4
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• pp.195-200
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• 2002

The objective of this survey is to characterize personal magnetic field exposure of the general population in Korea. The participants of the survey on magnetic field exposure were selected randomly in some occupations. The participant wore the magnetic field meter for about 25∼28 hours and the data were stored in the meter. Because this is a preliminary for the main survey, it was done with 36 participants only. For the main survey, about 400 subjects by occupation will be done. The statistics of the 24-hour exposure data are the major concern of this survey However the survey provided the opportunity to analyze exposures corresponding to different types of activities. It was analyzed by separating periods of time corresponding to the following activities: entire 24-hour period, in bed, at work and by occupation.

• Geophysics and Geophysical Exploration
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• v.6 no.1
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• pp.23-27
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• 2003

A magnetic survey on the lake war carried out to explore the possible UXO (unexploded ordnance) under the water. A magnetic gradiometer with 2 magnetometer sensors was used, which measures total magnetic intensity. For the positioning of the measurement points on the water, RTK (real time kinematic) survey system was used. The theoretical responses were calculated assumming the dimension and the material of the UXO so that the detectability could be investigated. Since the areal size of the survey vessel was rather small, the influence from the magnetic material of the vessel and the other equipments such as a laptop computer was not negligible, and the influence did not remain constant during the survey due to the change of survey direction. These effects were reduced remarkably using moving average technique. The result reveals the lineament of a pipe line laid on the bottom of the lake, which can be regarded as an indirect proof of detectability of the method.

• 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 Geophysical Society
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• v.3 no.3
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• pp.175-184
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• 2000

A nondestructive experimental feasibility study was conducted using magnetometer to find buried cultural objects at pottery and steel matters in low-relief mountaineous area of Doojeong-dong, Cheonan, Chungnam Province from May 23 to July 18, 1998. Magnetic survey was carried out with $20cm{\times}20cm$ grid in a site of $20m{\times}40m$ before excavation, and the distribution of magnetic anomalies was compared with the results of excavation. Magnetic sensor was located on the surface of ground during the magnetic survey on the basis of an experimental result. Positive magnetic anomalies of maximum 130 nT are found over a pair of potteries. Magnetic anomaly map reveals several anomalous points in the 1st and 4th quadrants of the survey site, from where potteries and their fragments were confirmed. Six points out of seven points cprrelated with magnetic anomaly are found contain earthwares, whereas a magnetically uncorrelated location produced earthware made of unbaked clay. Steel waste such as cans and wires hidden in soil and bushes also influenced magnetic anomalies. Therefore, it is better to remove such steel wastes prior to magnetic survey if possible. Some magnetically anomalous points produced no archaeological object on excavation. This may be explained by shallower level of excavation than burial depth.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.08a
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• pp.157-179
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• 2004

The application of magnetic method for archaeoprospection has been carried out through two archaeological areas in Egypt, Abydos and Abu Sir, In order to find out tile ancient Egyptian archaeological features. The magnetic work at the selected archaeological site of Abydos area was carried out by gradiometer survey, while magnetic work at the selected archaeological site of Abu Sir area was carried out by gradiometer survey and magnetic susceptibility measurements. A gradiometer survey with raster of 0.5 m/0.5 m has been carried out on a surface area of $9600 m^2$ at Abydos area to relocate the buried Solar Boats. The magnetic data were processed using Geoplot software to treat the field noises and enhance the quality of the obtained images. The final magnetic images indicate the existence of 12 Solar Boats as well as tombs, remains of ancient rooms and walls. All of them are expected to belong to the Middle Kingdom, particularly from the 18th to 20th Dynasties. Two magnetic tools have been applied over a selected site of $25600 m^2$ at Abu Sir area in order to detect the hidden archaeological features nearby the Sun Temple. The acquisition of the magnetic data was initiated by the measurements of the topsoil magnetic susceptibility of 272 samples collected from the whole studied area, and then followed by the gradiometer survey to measure tile vertical gradient of the geomagnetic field over an area of $14400 m^2$. The magnetic susceptibility results show the presence of high concentration at the middle part of the study area with a little extension to the south western side, with maximum value of about $36{\times}10^5$ SI. They may indicate the proximity of ritual monuments. Also, they offered the site of interest for carrying out a gradiometer survey. The gradiometer results show tile existence of numerous distributed archaeological features made of mud-bricks with different shapes and sizes. They may indicate tombs, burial rooms, dissected walls; all of them are expected to belong to the 5th Dynasty of pharaohs, who used to build their buildings by mud bricks. The depth of the expected buried archaeological features has been estimated from tihe gradiometer. It is around 1.2m for deep features and 0.42 m for shallow features.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.472-474
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• 2002

The objective of this survey is to characterize the personal magnetic field exposure of the Korean population. The participants in the survey on magnetic field exposure were selected randomly by occupation. In this first step survey, the number of participant is 108 and for the second step, about 400 participants will be surveyed in the near future. The survey is the first significant study that quantifies the exposure of the general population for the entire day, not only for the time spent in one's bed but also for the time at work in Korea.

• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.121-128
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• 2006

Magnetic survey flights by helicopters are usually parallel to the topographic surface, with a nominal clearance, but especially in high-resolution surveys the altitudes at which observations are made may be too variable to be regarded as a smooth surface. We have developed a reduction procedure for such data using the method of equivalent sources, where surrounding sources are included to control edge effects, and data from points distributed randomly in three dimensions are directly modelled. Although the problem is generally underdetermined, the method of conjugate gradients can be used to find a minimum-norm solution. There is freedom to select the harmonic function that relates the magnetic anomaly with the source. When the upward continuation function operator is selected, the equivalent source is the magnetic anomaly itself. If we select as source a distribution of magnetic dipoles in the direction of the ambient magnetic field, we can easily derive reduction-to-pole anomalies by rotating the direction of the magnetic dipoles to vertical.

• 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.

• Geophysics and Geophysical Exploration
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• v.22 no.1
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• pp.29-36
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• 2019

Regional airborne magnetic survey is very cost-effective mapping tool. Magnetic anomaly maps have abundant information, which are an important tool for understanding the geological evolution and mineral exploration. For this reason, the governments of many countries have made significant investment in the acquisition of airborne geophysical data over many decades. KIGAM (Korea Institute of Geoscience and Mineral Resources) began nationwide airborne magnetic mapping programme in 1982, and completed in 2017. The obtained magnetic data was reprocessed and magnetic database was built in 2018. In addition, the magnetic anomaly map of Korea with a scale of 1:1,000,000 was published. In this paper, we introduced a new magnetic anomaly map of Korea through describing the changing survey parameters during data acquisitions and history of data processing.