• Proceedings of the KSEEG Conference
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• 1999.04a
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• pp.80-85
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• 1999

본 연구에서는 토목분야에서 중요한 문제가 되는 기초 파일의 깊이 탐지와 관련하여 시추공 자력탐사의 적용성을 확인하기 위하여 시추공 자력탐사 모형 반응 계산 및 역산 알고리즘을 개발하였다. 모형 반응 계산은 시추공 자력탐사에 적합하고 삼성분 이상을 계산할 수 있도록 기존의 방법을 수정하였으며, 역산 알고리즘은 일반적인 자력탐사 자료 역산의 불안정성을 고려하여 광역적 최적화 기법의 하나임 ASA(Adaptive Simulated Annealing : Ingber, 1993)를 이용하였다. 개발된 모형 반응 및 역산 알고리즘을 간단한 모형 및 합성자료에 대해 적용한 결과 그 타당성을 검증할 수 있었다. 또한 실제 현장에서 부딪힐 수 있는 무작위 잡음을 첨가한 자료, 주변 파일의 영향 및 지표 구조물에 의한 영향을 고려한 복잡한 모형에 대해 기초 파일의 깊이를 탐지해 낼 수 있었으며, 이를 토대로 실제 현장 적용시 고려해야할 현장지침에 대해서도 고찰할 수 있었다. 마지막으로 실제 현장자료에 적용한 결과 실제 파일의 깊이를 역산해 낼 수 있음을 확인함으로써, 기초 파일의 깊이 탐지를 위한 시추공 자력탐사의 적용성 및 본 알고리즘의 현장 적용성을 확인할 수 있었다.

• 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.

• Geophysics and Geophysical Exploration
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• v.27 no.2
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• pp.119-128
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• 2024

Marine magnetic surveys provide a rapid and cost-effective method for pioneer geophysical survey for many purposes. Sea-surface magnetometers offer high accuracy but are limited to measuring the scalar total magnetic field and require dedicated cruise missions. Shipboard three-component magnetometers, on the other hand, can collect vector three components and applicable to any cruise missions. However, correcting for the ship's magnetic field, particularly viscous magnetization, still remains a challenge. This study proposes a new additional correction method for ship's viscous magnetization effect in vector data acquired by shipboard three-component magnetometer. This method utilizes magnetic data collected simultaneously with a sea-surface magnetometer providing total magnetic field measurements. Our method significantly reduces deviations between the two datasets, resulting in corrected vector anomalies with errors as low as 7-25 nT. These tiny errors are possibly caused by the vector magnetic anomaly and its related viscous magnetization. This method is expected to significantly improve the accuracy of shipborne magnetic surveys by providing corrected vector components. This will enhance magnetic interpretations and might be useful for understanding plate tectonics, geological structures, hydrothermal deposits, and more.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.40.1-40.1
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• 2010

한국천문연구원 우주과학연구본부 태양우주환경연구그룹은 일본 Tierra Tecnica사의 RFP-523C Overhauser Proton 자력계와 MISYS-09 삼축 MI 자력계를 2009년 11월에 보현산천문대 태양망원경동에 구축하였다. 한국천문연구원은 이미 2007년 11월에 RFP-523C Fluxgate 자력계를 보현산천문대 태양망원경동에 구축하여 K 지수 산출 등의 우주환경예 경보 연구에 활용하고 있다. Fluxgate 자력계는 지자기 3축 성분의 변화량을 측정하는 장비이고 이번에 설치한 Overhauser Proton 자력계는 지자기의 총 자기장을 측정하는 장비이다. 삼축 MI 자력계는 지자기장의wave를 측정하는 장비이다. 기존에 설치한 Fluxgate 자력계와 새로 설치한 Proton 자력계, 삼축 MI 자력계를 연계하여 운용할 경우 우주환경에 의한 지자기장 변화량의 측정 정밀도가 향상되고 지자기장을 효율적으로 관측할 수 있다. 보현산천문대에 구축한 각각의 자력계가 측정한 지자기 자료들은 S-FTP와 Socket 통신을 이용하여 대전에 있는 한국천문연구원 태양우주환경연구그룹의 데이터 서버로 실시간으로 전송되어 저장되고 있다. 데이터 서버로 전송된 지자기 측정 자료들은 한국천문연구원 우주환경감시실에서 모니터링하고 있다.

• Geophysics and Geophysical Exploration
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• v.17 no.3
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• pp.171-178
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• 2014

Aeromagnetic survey generally require much more pre-processing steps than that of common land survey due to several complex and cumbersome steps included in pre-processing stage. Therefore it is desirable to use specific processing tool especially based on graphic user interface. For this purpose, aeromagnetic pre-processing software based on graphic user interface under the Windows environment, called $KMagLevelling^{TM}$ was developed and briefly introduced. In an aspect of its user-friendliness and originality, three noticeable features of $KMagLevelling^{TM}$ are summarized as the following (1) function of representation and handling for large amount of aeromagnetic data set as a visualization in the form of flight-path (2) function of selective exclusion of unwanted data by using survey area information expressed as polygon, and (3) function of selective removal processing for the irregular flight-path data acquired within the entire survey area by implementing the segmentation of flight-path technique.

• Journal of the Korean earth science society
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• v.38 no.4
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• pp.251-262
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• 2017

The system of magnetic exploration with a drone flight was constructed and applied to the iron mine site. The magnetic probe system installed on the drone used a sensor as Bartington's fluxgate type magnetometer, Mag639 and the A/D converter to collect magnetic intensity values on the tablet PC. The drone flight control module is a highly expandable Pixhawk with allowing 15 minutes of flight by loading 3kg. Experiments on the magnetic field interference range were performed to remove the erroneous effect from the drone with applying RTK GPS to obtain the magnetic intensity value at the accurate position. The accurate location information enabled to obtain the gradient measurement of magnetic field by measuring twice at different altitudes. Also, by using the terrain information, we could eliminate the terrain effect by setting the flight path to fly along the terrain. These results are in line with the field experiments using the nuclear proton magnetometer G-858 of Geometrics Co., Ltd, which adds to the reliability of the drone based aeromagnetic survey system we constructed.

• 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.

• Journal of Astronomy and Space Sciences
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• v.19 no.4
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• pp.293-304
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• 2002

This paper describes the re-design and the calibration results of the MAG digital circuit onboard the KSR-3. We enhanced the sampling rate of magnetometer data. Also, we reduced noise and increased authoritativeness of data. We could confirm that AIM resolution was decreased less than InT of analog calibration by a digital calibration of magnetometer. Therefore, we used numerical-program to correct this problem. As a result, we could calculate correction and error of data. These corrections will be applied to magnetometer data after the launch of KSR-3.

• Economic and Environmental Geology
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• v.28 no.4
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• pp.395-404
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• 1995

The geologic structure of the Cheju volcanic island has been investigated by analyzing the gravity and magnetic data. Bouguer gravity map shows apparent circular low anomalies at the central volacanic edifice, and the maximum difference of the anomaly values on the island appears to be 30 mgal. The subsurface structure of the island is modeled by three-dimensional depth inversion of gravity data by assuming the model consists of a stacked grid of rectangular prisms of volcanic rocks bounded below by basement rocks. The gravity modeling reveals that the interface between upper volvanic rocks and underlying basement warps downward under Mt. Halla with the maximum depth of 5 km. Magnetic data involve aeromagnetic and surface magnetic survey data. Both magnetic anomaly maps show characteristic features which resemble the typical pattern of total magnetic anomalies caused by a magnetic body magnetized in the direction of the geomagnetic field in the middle latitude region, though details of two maps are somewhat different. The reduced-to-pole magnetic anomaly maps reveal that main magnetic sources in the island are rift zones and the Halla volcanic edifice. The apparent magnetic boundaries inferred by the method of Cordell and Grauch (1985) are relatively well matched with known geologic boundaries such as that of Pyosunri basalt and Sihungri basalt which form the latest erupted masses. Inversion of aeromagnetic data was conducted with two variables: depth and susceptibility. The inversion results show high susceptibility bodies in rift zones along the long axis of the island, and at the central volcano. Depths to the basement are 1.5~3 km under the major axis, 1~1.5 km under the lava plateau and culminates at about 5 km under Mt. Halla. The prominent anomalies showing N-S trending appear in the eastern part of both gravity and magnetic maps. It is speculated that this trend may be associated with an undefined fault developed across the rift zones.

• Geophysics and Geophysical Exploration
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• v.14 no.4
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• pp.298-304
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• 2011

We conducted magnetic survey using IBRV (Ice Breaker Research Vessel) ARAON of KORDI (Korea Ocean Research and Development Institute), ROV (Remotely Operated Vehicle) of Oceaneering Co. and three components vector magnetometer, at Apr., 2011 in the western slope of the caldera of TA25 seamount, the Lau Basin, the southwestern Pacific. The depth ranges of the survey area are from about 900 m to 1200 m, below sea level. For the deep sea magnetic survey, we made the nation's first small deep sea three components magnetometer of Korea. The magnetometer sensor and the data logger was attached with the upper part and lower part of ROV, respectively. ROV followed the planning tracks at 25 ~ 30 m above seafloor using the altimeter and USBL (Ultra Short Base Line) of ROV. The three components magnetometer measured the X (North), Y (East) and Z (Vertical) vector components of the magnetic field of the survey area. A motion sensor provided us the data of pitch, roll, yaw of ROV for the motion correction of the magnetic data. The data of the magnetometer sensor and the motion sensor were recorded on a notebook through the optical cable of ROV and the network of ARON. The precision positions of magnetic data were merged by the post-processing of USBL data of ROV. The obtained three components magnetic data are entirely utilized by finding possible hydrothermal vents of the survey area.