• Economic and Environmental Geology
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• v.3 no.1
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• pp.17-24
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• 1970

The purpose of this report is to prepare a data for the economic evaluation on the Goobong Limestone Mine which is located at the south-eastern corner of the Yongchun Quadrangle scaled in 1:50,000. The accessibility from the mine to railroad was considered in two ways. One is to Dodam Station on Central Railway Line and the other is to reach Songjung-ni village which is near Sangyong Station on Hamback Railway Line. The distance of the former way is 26.7km and the later is 24.2km. Geologically the mine is situated near the base of the Greast Limestone Series which strikes generally $N25^{\circ}{\sim}30^{\circ}E$. The series comprises six different formations from older to younger; Pungchon Limestone Formation and Whajol Formation of Cambrian age, and Dongjum Quartzite Formation, Dumudong Formation, Maggol Limestone Formation and Goseong Formation of lower to middle Ordovician age. 82 samples; 48 from Pungchon Limestone Formation, 11 from Dumudong Formation, 15 from Maggol Limestone Formation and 8 from Goseong Formation, were taken from the series in the crossed direction to the general trend of the series as shown in geological map. They were chemically analyzed on the components of CaO, MgO, $SiO_2$, $R_2O_3(Al_2O_3+Fe_2O_3)$ and ignition loss as shown in table 2, table 3, table 4, and table 5. As seen from the tables, among the formations of the series, middle to upper parts of the Pungchon Limestone Formation and middle and upper parts of the Dumudong Formation have chemical composition as available source for the raw material of cement industry, not only that but also the part of the Pungchon Formation was highly evaluated as source for the flux of iron smelting and the raw material of carbide manufacturing because of its high purity of calcium carbonate.

• Tunnel and Underground Space
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• v.30 no.2
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• pp.149-163
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• 2020

This paper presents a logistic regression and GIS based urban ground sink susceptibility assessment using underground facility information considering soil particle loss. In the underground environment, the particle loss due to water flow or groundwater level change leads to the occurrence and expansion of cavities, which directly affect the ground sink. Four different contributory factors were selected according to the two underground facility domains (water pipeline area, sewer pipeline area) and subway line area. The logistic regression method was used to analyze the correlation and to derive the regression equation between the ground sink inventory and the contributory factors. Based on these results, three ground sink susceptibility maps were generated. The results obtained from this study are expected to provide basic data on the area susceptible to ground sink and needed to safety monitoring.

• Tunnel and Underground Space
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• v.26 no.3
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• pp.166-180
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• 2016

The present study numerically simulated the CO2 injection into the saline aquifer of CO2CRC Otway pilot project and the resulting hydrological-mechanical coupled process in the storage site by TOUGH-FLAC simulator. A three-dimensional numerical model was generated using the stochastic geological model which was established based on well log and core data. It was estimated that the CO2 injection of 30,000t over a period of 200 days increased the pressure near the injection point by 0.5 MPa at the most. The pressure increased rapidly and tended to approach a certain value at an early stage of the injection. The hydrological and mechanical behavior observed from the CO2 flow, effective stress change and stress-strength ratio revealed that the CO2 injection into the saline aquifer under the given condition would not have significant effects on the mechanical safety of the storage site and the hydrological state around the adjacent fault.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.3
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• pp.171-180
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• 2005

Related to the tsunami impact caused by the 2004 Sumatra earthquake, field excursion of the title 'Tsunami impact on the coastal zone of Thailand' was carried out along the damaged coasts of Thailand fur three days. The damaged coastal zones along the Andaman Sea coasts of Thailand are classified into the severely damaged, the moderately damaged, and the slightly damaged coastal zone by the degree of damage. Channels of the river- mouths were widen, and the beach sands were eroded, transported, and then redeposited in the near shore or in the back beach area. Field excursion stops were 12 in the representative areas like Phang Nga province, the severely damaged coastal zone and Phuket Island, the slightly damaged coastal zone. In this report, the geo-logical effects on the coastal zone of Thailand by tsunami will be mainly illustrated by the satellite data before and after tsunami and the photographs taken during the field excursion.

• Geosciences Journal
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• v.22 no.6
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• pp.1001-1013
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• 2018

A new type of uranium occurrence in Korea was identified in pegmatitic and hydrothermally altered granite in the Daejeon area. The U-bearing parts typically include muscovite, pink-feldspar and sericite as alteration minerals. In this study, the geochemical characteristics and alteration age of the granitic rocks were examined to provide evidence for hydrothermally-enriched uranium. The K-Ar ages of muscovite coexisting with U-bearing minerals were determined as 123 and 128 Ma. The U-bearing rocks have relatively low ($CaO+Na_2O$), high $K_2O$ contents, and high alteration index values by major element geochemistry. The trace element geochemistry shows that the uraniferous rocks have significantly low Th/U ratios and strongly differentiated features. The rare earth element patterns indicate that the uraniferous rocks have a low total REE and LREE contents with depletion of Eu. Considering the geochemical variation of the granitic rock major, trace and rare earth elements, it can be concluded that uranium enrichment in pegmatites and altered granite should be genetically related to post-magmatic hydrothermal alteration of K-metasomatism after emplacement of the two-mica granite. This is the first report for geochemical characteristics of Mesozoic granite-related U-occurrences in South Korea. This study will help further research for uranium deposits with similarities in geological setting, mineralogy and age data between South China and Korea, and can also be expected to help solve the source problems related to high uranium concentrations in some groundwater occurring in the granitic terrane.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.505-505
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• 2017

최근 하천의 유량측정에 있어서 ADCP(Acoustic Doppler Current Profiler)의 빈도와 활용범위가 점차적으로 증가하고 있다. 국토교통부의 유량측정을 전담하고 있는 유량조사사업단에서는 최근 저평수기 유량측정은 물론, 중고수위 유량측정에서도 기존 유량측정방법의 단점을 보완하기 위해 ADCP 이동보트법을 적극적으로 활용하고 있다. 현재 ADCP 이동보트법으로 측정된 유량은 제조업체에서 제공되는 소프트웨어로 산정되며 크게 두 가지 문제를 초래하고 있다. 첫째, 제조업체에서 제공한 소프트웨어는 자동으로 품질평가를 할 수 있는 기능이 제한적이고, 사용자가 측정자료를 검토하기 위해 제공되는 표와 그래프 등의 정보가 제조업체마다 일관적이지 않다. 따라서, 측정자료의 품질평가는 측정한 ADCP에 종속되고 제조업체에서 제공된 소프트웨어 기능에 한정되어 효율적인 평가는 저해되고, 일관적이지 못한 결과를 초래하여 측정자의 책임이 증가되고 있다. 둘째, 제조업체에서 제공되는 소프트웨어가 자료의 처리 및 유량 계산에 대한 상이한 알고리즘을 사용하여 제조업체가 다른 ADCP로 동시에 측정된 유량이 서로 다른 결과로 나타나 혼란을 주고 있다. 이러한 이유로 USGS(U.S.Geological Survey)에서는 ADCP를 이용한 이동보트법 측정유량 처리에 대한 소프트웨어인 QRev를 개발하였으며, 일관적이고 효율적인 자료 처리와 계산이 이루어지도록 하고 있다. 본 연구에서는 유량조사사업단에서 수행한 ADCP 이동보트법 측정유량 자료에 대하여 QRev를 이용한 자료의 처리 결과에 대하여 분석하였다. 특히, ADCP로 측정이 불가능한 수면 및 하상 영역에 대한 외삽방법들의 적용 결과 및 제조업체의 기본 설정 값들에 대한 결과를 비교함으로서 QRev에 대한 향후 국내 활용 방향을 제시하고자 한다.

• Geophysics and Geophysical Exploration
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• v.8 no.3
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• pp.207-217
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• 2005

We present a new approximate formulation of the integral equation (IE) method for models with variable background conductivity. This method overcomes the standard limitation of the conventional If method related to the use of a horizontally layered background only. The new approximate IE method still employs the Green's functions for a horizontally layered 1-D model. However, the new method allows us to use an inhomogeneous background with the IE method. The method was carefully tested for modeling the EM field for complex structures with a known variable background conductivity. It can find wide application in modeling EM data for multiple geological models with some common geoelectrical features, like a known inhomogeneous overburden, or salt dome structures.

• Journal of the Korean GEO-environmental Society
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• v.20 no.2
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• pp.29-40
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• 2019

Mechanized constructions have been frequently increased in soft ground below sea bed or river bed, for urban tunnel construction, and for underpinning the lower part of major structures in order to construct a safer tunnel considering various risk factors during the tunnel construction. However, it is difficult to estimate the subsidence behavior of the ground surface due to excavation and needs to be easily predicted. Thus, in this study, when a twin tunnel is constructed in the soft ground, it is proposed a simpler equation relating to the settlement behavior and a corrected formula applicable to soft ground and large diameter shield tunnels based on the previously proposed theory by Peck (1969). For this purpose, it was analyzed to long-term measurement values such as the amount of maximum settlement, the subsidence range by ground conditions, and interference volume loss due to the parallel construction, etc. As a result, a equation was suggested to predict the amount of maximum settlement in the soft sediment clay ground where is located at the upper part of the excavation site. It is turned out that the proposed equation is more suitable for measurement data in Korea than Peck (1969)'s.

• Journal of Climate Change Research
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• v.7 no.3
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• pp.269-282
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• 2016

Watershed area can be submerged due to constructions and management of dams, and these change can impact not only on ecosystem and environment of river basin area but also on local climate. This study is conducted to construct and classify climate zones of Andong Dam watershed where the area is submerged due to the construction of the dam. By applying Principal Components Analysis (PCA) and Getis-Ord $Gi^*$ statistics, three climate zones were classified for the result. Each zone was then analyzed and validated with climatic and geological features including topography, land cover, and forest type map. As a result of the analysis, there was a difference in temperature, elevation, precipitation and tree species distribution among the zones. Also, an analysis of land cover map showed that there were more agricultural land near Andong Reservoir. This study on the climatic classification is considered to be useful as the basis for decision-making or policy enforcement regarding ecosystem, environmental management or climate change response.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.658-669
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• 2020

The horizontal-to-vertical spectral ratio (HVSR) analysis is conducted to estimate the site amplification effect and the thickness of the sedimentary layer beneath the measurement site. We investigated the effects of meteorological variations (wind and precipitation rate) and sensor burial depths on HVSR analysis. The HVSR results were unstable when seismographs were exposed on the ground. The HVSR results of ambient noise data measured under strong winds were also unstable. It is recommended to measure the ambient noise at wind speeds of <3 m s-1. Stable HVSR results were obtained when seismographs were buried, regardless of the precipitation rates. The results of this study provide the best observations and optimal weather conditions required to acquire accurate and reliable HVSR results.