• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.273-278
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• 2007

2-D MT surveys at the Century mine in Australia have been performed with very far remote reference in Esashi, Japan as well as Gregory Downs, which are roughly 6400 km and 80 km apart from the field site, respectively. Long period pulsations observed in this survey generally showed dominant $H_x$ polarization than $H_y$; $H_x$ component is more than 3 times stronger than $H_y$ component. Polarity reversal in magnetic field pointing east ($H_y$ component) has also been observed in long period pulsations, while $H_x$ component remain coherent between the hemispheres. Though $H_x$ component shows relatively good coherency than $H_y$ component between the hemispheres at frequencies lower than 0.01 Hz, it seems rather too far to be used as a remote reference for ordinary MT frequency band.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.345-352
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• 2007

Two-dimensional (2D) MT surveys near the Century mine in Australia have been performed with very far remote reference in Esashi, Japan (RR_ESS) as well as Gregory Downs (RR_GREG), which are roughly 6,400 km and 80 km apart from the survey area, respectively. Good quality of MT data could be obtained by remote reference processing with RR_GREG, while the coherency of magnetic fields between field sites and RR_ESS was not sufficient to be used as remote data. Both 2D and 3D inversion of 2D profile data represented the general geological structure beneath the survey area. The main target of the survey, Termite Range Fault, appeared as a boundary between a conductive block to the north and a resistive block to the south in the reconstructed resistivity section, and is inclined slightly to the north-east direction.

• Geophysics and Geophysical Exploration
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• v.27 no.2
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• pp.129-143
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• 2024

In magnetotelluric (MT) surveys, small inhomogeneities near the surface cause a static shift in which apparent resistivities shift regardless of frequency. As the static shift in MT data leads to errors in subsurface structure interpretation, many studies have been conducted over the past few decades to mitigate or remove the distortions it caused. The most representative method involves removing static shifts from the data before inversion. Conversely, static shifts can be corrected during inversion or included in the inversion process. In addition, other geophysical data can be used to remove static shifts. However, the correction methods are limited to one-dimensional (1D) static responses, and limitations remain in two- or three-dimensional (2D or 3D) interpretation of distorted MT data owing to static shifts. This study provides a foundation for future studies on static shift by analyzing several previously published methods.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.434-437
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• 2006

Though numerous drilling has been performed in Jeju Island for development of ground water, the wells are mostly located along the coast lines or at low altitude area, and can hardly be found on the mid-mountain area. Two-dimensional magnetotelluric (MT) surveys have been carried out to cover the lack of geological Informal ion on the mid-mountain area and to figure out any possible structures or evidences for deep geothermal energy remained. Two-dimensional (2-D) inversion of MT data for four survey lines surrounding the Halla mountain show a thick layer having around 10 ohm-m in the depth of a few hundred meters throughout the survey area, which can be considered as the unconsol idated sedimentary layer. And they also show a conductive anomaly extending to more than 2km depth at the central part of each survey lines, which can possibly be related with old volcanic activities during the formation of Halla Mt.. Further seological/geophysical investigations should be followed.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.61-68
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• 2010

A magnetotelluric (MT) survey has been performed to delineate deeply extended fracture systems at the geothermal field in Seokmo Island, Korea. To assist interpretation of the MT data, geological surveying and well logging of existing wells were also performed. The surface geology of the island shows Cretaceous and Jurassic granite in the north and Precambrian schist in the south. The geothermal regime has been found along the boundary between the schist and Cretaceous granite. Because of the deep circulation along the fracture system, geothermal gradient of the target area exceeds $45^{\circ}C/km$, which is much higher than the average geothermal gradient in Korea. 2D and 3D inversions of MT data clearly showed a very conductive anomaly, which is interpreted as a fracture system bearing saline water that extends at least down to 1.5 km depth and is inclined eastwards. After drilling down to the depth of 1280 m, more than 4000 tons/day of geothermal water overflowed with temperature higher than $70^{\circ}C$. This water showed very similar chemical composition and temperature to those from another existing well, so that they can be considered to have the same origin; i.e. from the same fracture system. A new geothermal project for combined heat and power generation was launched in 2009 in Seokmo Island, based on the survey. Additional geophysical investigations including MT surveys to cover a wider area, seismic reflection surveys, borehole surveys, and well logging of more than 20 existing boreholes will be conducted.

• Korean Journal of Plant Taxonomy
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• v.41 no.3
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• pp.287-297
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• 2011

The objective of this study was to discuss the characteristics of the moss flora of Mt. Deogyu located on the border of the Jeonbuk and Kyungnam provinces in Korea. A total of 21 field surveys were carried out at various sites in the mountain area from August 2007 to September 2008. All the collected materials were processed into voucher specimens and were currently deposited in the herbarium at Chonbuk National University (JNU). In this study, we collected and identified 158 moss taxa, which included 156 species, 1 subsp. and 1 var. of 96 genera and 37 families. Unconfirmed taxa in this study, but previously recorded, belonged to 25 taxa, which included 13 families, 19 genera and 25 species. In addition, 183 taxa were found on Mt. Dreogyu, which belonged to 37 families, 101 genera, 1 subsp. and 1 var. The habitat of each collection was examined and the classification system of Ignatov et al. (2006) was used. New vernacular names of 6 families and 11 genera were then determined. Six species, formerly thought be only in North Korea, were shown to be present on Mt. Deogyu, which included Bucklandiella laeta, Anomobryum filiforme var. concinnatum, Herzogiella turfacea, Brachythecium rutabulum, Eurhynchium angustirete and Campylidium hispidulum.

• Geophysics and Geophysical Exploration
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• v.8 no.4
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• pp.251-261
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• 2005

The quality of MT (magnetotellurics) data highly depends on the level of artificial noise form industrial sources. We have conducted the feasibility study of MT noise modelling using digital spatial data and spatial modelling through the comparison between the predicted and the measured MT noises. A simple noise model predicting the intensity of electromagnetic field radiated from the latent noise sources, that is, the electric facilities in the building, road and high-voltage powerline, is developed in consideration of the propagation property of electromagnetic waves. From the analysis of correlation between the predicted and the measured noise power, the correlation coefficients of electric field are higher than those of magnetic field in whole frequency band. The magnetic field component has the high correlation in the narrow band near 60 Hz only. The spatial noise modelling proposed in this study would provide some useful informations for the MT surveys in the noisy environment like urban area.

• Korean Journal of Plant Taxonomy
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• v.51 no.1
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• pp.33-48
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• 2021

We investigated the bryophyte flora of the Gayasan Mountain National Park in Korea by conducting 18 field surveys in from April of 2009 to November of 2016 at various sites on the mountains. During the surveys, we discovered 204 taxa comprising 57 families, 106 genera, 199 species, 2 subspecies, and 3 varieties. Among these, 145 species were reported as new to the flora of Gayasan Mountain. A checklist based on a study of 903 specimens is provided. The most notable species recorded during the surveys were the rare bryophytes Hattoria yakushimensis (Horik.) R. M. Schust., Nipponolejeunea pilifera (Steph.) S. Hatt., Drepanolejeunea angustifolia (Mitt.) Grolle, Lejeuena otiana S. Hatt., Cylindrocolea recurvifolia (Steph.) Inoue and Pogonatum contortum (Menzies ex Brid.) Lesq.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.151-154
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• 2005

With the aim of global environmental monitoring we carried out GPR (Ground Penetrating Radar) surveys at the Livingstion Island in Antarctica. Research area is near the Mt. Charra (340m) in Livingston Island which is located 80 km to the southwest of the King Sejong Station. We have collected 5 lines of GPR data. Two kinds of survey, CMP (Common Midpoint) surveys and common offset profiles, were performed. We classified the glacier into the three layers using electromagnetic velocity of the ice and reflection characteristic, The depth of glacier reached about $80{\~}110\;m$. Some reflectors showed the evidence of the water filled englacial drainage and volcanic ash-layers.

• Journal of the Korean earth science society
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• v.18 no.6
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• pp.522-528
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• 1997

Gravity surveys with accompanying spirit levelings were carried out in Mt. Hangye area. From these survey results, orthometric height correctioins were calculated. The correction reaches 5 cm when the height difference is 900 m in this area. The corrections were also calculated using an available Bouguer anomaly map, and they are little different from the previous results. In conclusion, orthometric height corrections are necessary in precise spirit leveling, specially in higher lands, and they can be easily calculated from an available Bouguer anomaly map without laborious gravity surveys.