• Journal of Conservation Science
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• v.25 no.1
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• pp.61-76
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• 2009

Gwangjueupseong (Gwangju Town Wall) has been found in the site of the Asian Culture Complex (former Provincial Government of Jeonnam) by archaeological field survey. The length of the remaining wall is 85.1m, and the Town Wall consists of ten kinds of rock type. The major rock types are dacite (41.1%) and andesite (35.7%). Dacite composes main rock blocks of the wall, and andesite is used to fill the cavity between main rock blocks. These rocks look very similar to basement rocks of the Mudeung Mountain on the basis of occurrence features, magnetic susceptibility, petrological, mineralogical and geochemical properties. Also, quarrying traces were found on the southwestern slope of the mountain along the Jeungsimsa Temple valley. Thus, it is probable that the rock materials of the Gwangju Town Wall were supplied from the Mudeung Mountain and that they were transported along the Gwangju river.

• Nuclear Engineering and Technology
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• v.36 no.2
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• pp.196-202
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• 2004

KAERI (Korea Atomic Energy Research Institute) is at present preparing a preliminary performance assessment to set up the HLW disposal concept of Korea. The solubility of the radionuclides contained in HLW is necessary as a source term in order to predict their potential migration in both the near and far fields. The solubility of actinides (Th, Am, U, Np and Pu) for a reference deep groundwater of Korea has been calculated using a geochemical code with thermodynamic data selected by a peer review of existing thermodynamic databases and literature. The solubilities from the experimental study and/or field observations from natural analogue studies are compared. The sensitivity of solubility to the variability of three main parameters of groundwater (pH, Eh, and carbonate concentration) is also investigated. The results of the sensitivity analysis show that the solubility of actinides strongly depends on the parameters considered. Within the range of parameter values studied (pH=7 to 10, Eh=-0.4 to -0.1V, and carbonate concentration=1.E-5 to 1.E-2 mol/L), the solubility of each actinide exists between 1.4E-10 and 1.6E-6 mol/L for Am, 4.9E-9 and 2.8E-6 mol/L for Th, 3.2E-9 and 5.7E-4 mol/L for U, 1.1E-9 and 1.0E-7 mol/L for Np, and 4.0E-11 and 2.8E-6 mol/L for Pu, respectively.

• Korean Journal of Remote Sensing
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• v.23 no.4
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• pp.287-295
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• 2007

A mineral potential map showing the distributions of potential areas for exploration of undiscovered mineral deposits is a kind of predictive thematic maps. For any predictive thematic maps to show reasonably significant prediction results, validation information on prediction capability should be provided in addition to spatial locations of high potential areas. The objective of this paper is to apply prediction rate curves to the estimation of prediction probability of future discovery. A case study for Au-Ag mineral potential mapping using geochemical data sets is carried out to illustrate procedures for estimating prediction probability and for an interpretation. Through the case study, quantitative information including prediction rates and probability obtained by prediction rate curves was found to be very important for the interpretation of prediction results. It is expected that such quantitative validation information would be effectively used as basic information for cost analysis of exploration and environmental impact assessment.

• Korean Journal of Remote Sensing
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• v.10 no.2
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• pp.37-48
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• 1994

In spatial information processing, particularly in non-renewable resource exploration, the spatial data sets, including remote sensing, geophysical and geochemical data, have to be geocoded onto a reference map and integrated for the final analysis and interpretation. Application of a computer based GIS(Geographical Information System of Geological Information System) at some point of the spatial data integration/fusion processing is now a logical and essential step. It should, however, be pointed out that the basic concepts of the GIS based spatial data fusion were developed with insufficient mathematical understanding of spatial characteristics or quantitative modeling framwork of the data. Furthermore many remote sensing and geological data sets, available for many exploration projects, are spatially incomplete in coverage and interduce spatially uneven information distribution. In addition, spectral information of many spatial data sets is often imprecise due to digital rescaling. Direct applications of GIS systems to spatial data fusion can therefore result in seriously erroneous final results. To resolve this problem, some of the important mathematical information representation techniques are briefly reviewed and discussed in this paper with condideration of spatial and spectral characteristics of the common remote sensing and exploration data. They include the basic probabilistic approach, the evidential belief function approach (Dempster-Shafer method) and the fuzzy logic approach. Even though the basic concepts of these three approaches are different, proper application of the techniques and careful interpretation of the final results are expected to yield acceptable conclusions in cach case. Actual tests with real data (Moon, 1990a; An etal., 1991, 1992, 1993) have shown that implementation and application of the methods discussed in this paper consistently provide more accurate final results than most direct applications of GIS techniques.

• Journal of The Geomorphological Association of Korea
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• v.24 no.3
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• pp.83-103
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• 2017

Sand deposit with shell units is exposed in Hasa-ri, Yeonggwang-gun, Jeonnam province. We investigated the characteristics of sand sediment topography in the Yeonggwang coastal area to collect evidence of the paleo-environmental change. We performed analysis on particle characteristics, chemical composition, and the age of deposition of sediments. The deposit comprise moderately well sorted medium and fine sand ($1.00{\sim}2.19{\varphi}$). Various sedimentary structures can be observed. Geochemical characteristics change by depth and the degree of variation with depth is small. The results obtained from OSL dating show that sand layers below shell units are deposited 0.32-0.43 ka. As the elevation of the shell unit far mean high water levels or highest high water level, the extensive shell layers could only have been deposited during storm surge conditions. Aeolian processes are discounted due to the size of clasts and the location at which they occur. Results of age dating of the surrounding deposits indicate shell deposits formed after around 300 years age. There is a distinct difference between sedimentary layers including dark brown-black layer. The sedimentary characters such as particle size and geochemistry show difference with depth. It is presumed that depositional environmental in Hasa-ri has changed several times before. This study is expected to contribute to finding an evidence about occurrence of storm surges.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.2
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• pp.227-234
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• 2019

A user-friendly modeling interface is developed for a process-based total system performance assessment framework (APro) specialized for a generic geological disposal system for high-level radioactive waste. The APro modeling interface is constructed using MATLAB, and the operator splitting scheme is used to combine COMSOL for simulation of multiphysics and PHREEQC for the calculation of geochemical reactions. As APro limits the modeling domain to the generic disposal system, the degree of freedom of the model is low. In contrast, the user-friendliness of the model is improved. Thermal, hydraulic, mechanical and chemical processes considered in the disposal system are modularized, and users can select one of multiple modules: "Default process" and multi "Alternative process". APro mainly consists of an input data part and calculation execution part. The input data are prepared in a single EXCEL file with a given format, and the calculation part is coded using MATLAB. The final results of the calculation are created as an independent COMSOL file for further analysis.

• Journal of The Geomorphological Association of Korea
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• v.25 no.2
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• pp.63-80
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• 2018

The purpose of this study was to investigate the physicochemical characteristics and formation age of sand dunes in the Okjukdong and Dajindong, Daecheong Island. As a result, most of the sand deposited in Okjukdong were composed of medium sized sand with moderately well sorted. The $SiO_2$ and $Al_2O_3$ accounted for a very high proportion of these deposits. There were some differences in characteristics between the sands in the dune and beach, whereas similar characteristics were observed among the materials (OJ-B, OJ-C and OJ-D) in the dune. In case of Dajindong, heterogeneous geochemical characteristics were found in the lower point. It was estimated that this was due to the influence of Daejin-dong black beach. Age dating results showed that uncovered dunes in Okjukdong were deposited $0.44{\pm}0.02$ ~ $0.50{\pm}0.02ka$, and sand depositsin Dajindong were formed $0.16{\pm}0.01$ ~ $0.18{\pm}0.01ka$. In both Okjukdong and Dajindong, sand deposits estimated to be formed 70 years ago, therefore it can be estimated that sand movement was active throughout the area from about hundred years ago. In this study area, the growth of sand dunes has been active in recent several decades or hundred years. It seems that there were different regions where deposits predominated over time. The source of dune sand was also different from time to time. Since the windbreak forest was established, the natural growth of sand dunes was limited, and sand nourishment was carried out by period. Therefore, in order to protect and continuously utilize coastalsand dunesin Daecheong Island, it is necessary to prepare conservation plan.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1476-1484
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• 2023

Laboratory experiments and point monitoring of reservoir sediments have proven that stable sulfate reduction (SSR) can lower the concentrations of toxic metals and sulfate in acidic groundwater for a long time. Here, we hypothesize that SSR occurred during in situ leaching after uranium mining, which can impact the fate of acid groundwater in an entire region. To test this, we applied a sulfur isotope fractionation method to analyze the mechanism for natural attenuation of contaminated groundwater produced by acid in situ leaching of uranium (Xinjiang, China). The results showed that δ³⁴S increased over time after the cessation of uranium mining, and natural attenuation caused considerable, area-scale immobilization of sulfur corresponding to retention levels of 5.3%-48.3% while simultaneously decreasing the concentration of uranium. Isotopic evidence for SSR in the area, together with evidence for changes of pollutant concentrations, suggest that area-scale SSR is most likely also important at other acid mining sites for uranium, where retention of acid groundwater may be strengthened through natural attenuation. To recapitulate, the sulfur isotope fractionation method constitutes a relatively accurate tool for quantification of spatiotemporal trends for groundwater during migration and transformation resulting from acid in situ leaching of uranium in northern China.

• The Journal of the Petrological Society of Korea
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• v.25 no.4
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• pp.373-388
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• 2016

To understand human activity in the past, the information about past environmental change including geomorphological and climatic conditions is essential and this can be traced by using age dating and geochemical analysis of sediments from the prehistoric sites. The sedimentary sequence of Seokgwan-dong Paleolithic Site located in Seoul was 5m long unconsolidated sediments and consists of lower part bedrock weathering sediments, slope deposits and upper-part fluvial deposits. In this study, upper part sediments were used to reconstruct past environmental change through age dating and various physical and chemical analyses including grain size, magnetic susceptibility and mineral and elements. The fluvial sediments can be divided into 4 units including three organic layers. Grain size analysis results showed that the sediments were very poorly sorted with fining upward features. Magnetic susceptibility was relatively high in the organic layers, indicating environmental changes causing mineral composition change at that times. The mineral and major element composition are similar to Jurassic biotite granite which mainly consists of quartz, K-feldspar, biotite and muscovite. The radiocarbon age of $14,240{\pm}80yr$ BP was obtained from the lower most organic layer of Unit III(O), suggesting that the fluvial sediments formed at least from the early stage of deglacial period after the end of Last Glacial Maximum. Subsequent wet and warm climates and resultant fluvial process including slope sedimentation during the Holocene may have been responsible for the sedimentary sequence in Seokgwan-dong paleolithic site and surrounding area. The observed organic layers suggests frequent wetland occurrence combined with natural levee changes in this area.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.293-304
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• 2017

This study was performed in order to hydrogeological analysis of aquifer, which is a necessary part for evaluating the efficiency of the combined well and open-closed loops geothermal (CWG) systems. CWG systems have been proposed for the effective utilization of geothermal energy by combining open loop geothermal systems and closed loop geothermal systems. Small aperture CWG systems and large aperture CWG systems were installed at a green house land with water curtain facilities in Chungju City. Aquifer tests include pumping tests and step-drawdown tests were conducted to analyse hydrogeological characteristics of aquifer in the study area. The transmissivity was estimated in the range of $13.49{\sim}58.99cm^2/sec$, and the storativity was estimated in the range of $1.13{\times}10^{-5}{\sim}5.20{\times}10^{-3}$. The geochemical analysis showed $Ca^{2+}$ ion and ${HCO_3}^-$ ion were dominant in groundwater. The Langelier Saturation Index and the Ryznar Stability Index showed low scaling potential of groundwater. In the analysis of vertical water temperature change, the geothermal gradient was estimated as $2.1^{\circ}C/100m$, which indicated the aquifer was enough for geothermal systems. In conclusion, groundwater is rich, can stably use geothermal heat, and it is less likely to cause deterioration of thermal energy efficiency by precipitation of carbonate minerals in study area. Therefore, the study area is suitable for installation of the combined geothermal system.