• The Journal of Engineering Geology
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• v.16 no.1 s.47
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• pp.85-96
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• 2006

This study was conducted to suggest a method to determine weighting values of each parameter of the RMR system considered with geologic characteristics of a study area. This study reviewed the weighting values of the RMR system for the Cretaceous sedimentary rocks distributed in Ulsan area. Based on the data of field survey at the study area, a multiple regression analysis was used to set up an optimal weighting values of the RMR parameters. For the multiple regression analysis, each parameter of the RMR and the slope gradient were regarded as the independent variable and the dependent variable, respectively. The analysis result suggested a modified weighting values of the RMR parameters as follows; 30 for the intact strength of rock; 18 for RQD; 8 for spacing of discontinuities; 32 for the condition of discontinuities; and 12 for ground water.

• The Journal of Engineering Geology
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• v.3 no.2
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• pp.101-114
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• 1993

GIS technique was applied to identify the regional hydrologic units for groundwater exploitation and recharge analysis in a study area. The technique was very effective to identify the potential areas for groundwater exploitation, and for groundwater management & land use planning. GIS database of environmental resources was complied from a variety of sources and scales as the foundation for analysis, including digitizing and scanning of hardcopy maps. A DEM(Digital Elevation Model) was used to dassify slopes, and identify problematic drainage system. Quantitative analysis of environmental resources helps us to develop the scoring system of GIS model, which evaluates each resource in relation to the others and reflects the relative importance of each resource. ARC4NFO was used to construct digital database, and the cartographic simulation techniques were applied in order to create new maps.

• The Journal of Engineering Geology
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• v.7 no.3
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• pp.161-171
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• 1997

The exact information on geological structures and characteristics of the subsurface must be acquired to secure quality and safety of constructions. GPR technique, one of the most updated geophysical methods, is known for its applicability to shallow-depth underground surveys. The purpose of this study is to examine the usefulness of GPR method in constructions for detailed subsurface investigations, especially detecting the boundary between basement rock and its overburden. To find appropriate depths of the geological boundaries, it is necessary to obtain velocity of electromagnetic wave propagating into the ground. Wave velocity 0.096 m/ns estimated from velocity analysis using CMP gathers is used for depth conversion from time section. The depths of geological boundaries from GPR profiles are very well correlated with boring data. In addition, GPR survey has found some undulations of the geological boundaries due to weathering, which cannot be provided by conventional coring approaches.

• The Journal of Engineering Geology
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• v.15 no.4 s.42
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• pp.475-486
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• 2005

According to the inference results of formation process of the tectonic lineament, totally four events of subsidence including two events after upheaval of granite body and two events after sedimentation of unconsolidated sedimentary layer formed the macroscopic tensional lineament. The subsidence was occurred by tensional stress oriented ENE-WSW direction and compressional stress oriented NNW-SSE direction. The deeper distribution of tuff and unconsolidated sedimentary layer as much as 70-140m and that of granite as much as 50-500m at Hamdeok and Shinheung than those of the eastern and the western area around Hamdeok and Shinheong is due to the Hamdeok-Pyoseon Graben by three events of differential subsidence from Hamdeok to Pyoseon including Shinheung.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.577-587
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• 2007

The length of study area was about 450m, and it was shown the geological condition of distinguished change of rock by cutting slope. In order to establish a slope stability, we carried out an engineering geological investigations about rock constituent, rock structure and a direction of discontinuous plane. The study area was divided into six section considered by direction of cutting slope, height of slope and geological condition. Analysis of cutting slope stability was carried out with stereo-graphic projection method by DIPS program which was feasible of stability analysis with geometrical correlation for a direction of discontinuous plane and direction of cutting slope. From analysis of cutting slope stability considered by construction, stability and economical efficiency, the slope stability countermeasures such as a high tensile wire net, slope protection method and enhanced retaining wall were established and operated which minimized effect caused by lower end of road on a relaxation of huge rock.

• The Journal of Engineering Geology
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• v.5 no.2
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• pp.167-179
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• 1995

The only three elements such as RQD, N -value and Es were used as a quantitative standard for the design of supporr pattern determidetion on subway line 8th in Seoul. Because the support pattern that was obtained by these elements could not he determined on the basis of the quantitative of geology and the orientations and properties of discontinuity planes, there have been some problems in determining the economic support pattern and tunnel stability. Therefore, in an attempt to determine the stable and economic support pattern with more quantitative elements, more flerrible rock mass classification with geologic conditions was performed by using RMR at 1745 sections and Q-system at 374 sections within Seongnam block on subway line 8th. Then, rusults by these two methods were compared with standard support pattern of the subway line 8th. Moreover, relationships between geology, geologic structures and topography to rock mass grades were studied. According to the rusult of this study, it is judged that the standard support pattern designed with PD-4 or PS - 4 should have been subdivided into 4~6 support patterns. Some sections where geologic structures such as faults and joints are developed tend to have rock mass grades. And they also have low rock mass grades near valley. On thr other hand, they show intermediate grades at piedmont area and the greatest ones at high mountains.

• The Journal of Engineering Geology
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• v.22 no.4
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• pp.449-458
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• 2012

A sound understanding of the structural characteristics of fractured rock masses is important in designing and maintaining earth structures because their strength, deformability, and hydraulic behavior depend mainly on the characteristics of discontinuity network structures. Despite considerable progress in understanding the structural characteristics of rock masses, the complexity of discontinuity patterns has prevented satisfactory analysis based on a 3-D rock mass visualization model. This paper presents the results of studies performed to develop rock mass visualization in 3-D to analysis the mechanical and hydraulic behavior of fractured rock masses. General and particular solutions of non-linear equations of disk-shaped fractures have been derived to calculated lines of intersection and equivalent pipes. Also, program modules have been developed to perform the calculations. The procedures developed for the 3-D fractured rock mass visualization model can be used to characterize rock mass geometry and network systems effectively. The results obtained in this study will be refined and then combined for use as a tool for assessing geomechanical problems related to strength, deformability and hydraulic behaviors of the fractured rock masses.

• Korean Journal of Remote Sensing
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• v.20 no.6
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• pp.369-382
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• 2004

The purpose of this study is the investigation of applicability of LSMA(Linear Spectral Mixture Analysis) on the geological uses with different radiometric and spatial types of sensor images such as Terra ASTER and LANDSAT 7 ETM+. As for the actual application case, geologic mapping for mineral exploration using ASTER and ETM+ at the Mongolian plateau region was carried out. After the pre-processing such as the geometric corrections and calibration of radiance, 7 endmembers, as spectral classes for geologic rock types, related to spectral signature deviation for the given application was determined by the pre-surveyed geological mapping information and the correlation matrix analysis, and total 20 images of ASTER and ETM+ were used to LSMA processing. As the results, fraction maps showing individual mineral types in the study area are presented. It concluded that this approach based on LSMA using ETM+ and ASTER is regarded as one of the effective schemes for geologic remote sensing.

• The Journal of the Convergence on Culture Technology
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• v.8 no.3
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• pp.551-557
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• 2022

Geotechnical risk factors encountered in intermediate-depth underground tunnel construction are diverse, and the types and standards of risk factors are different according to the depth and regional geological characteristics of Korea. In order to understand the effects of geological characteristics and geologic structure on safety, which show various porous characteristics of urban underground complex ground, the risk factors of intermediate-depth rock mass in Korea were analyzed based on domestic and foreign cases. As a result of the study, seven categories affecting the stability of the intermediate-depth tunneling, namely, geologic structure, rock characteristics, hydrogeology, overburden, high stress, ground characteristics and artificial structures, and about 22 risk factors were derived. We present the risk criteria and interval values for risk evaluation of faults, folds, dikes, and rocks that have the greatest influence among risk factors. Criteria and interval values for other risk factors are under study.

• Geophysics and Geophysical Exploration
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• v.26 no.3
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• pp.138-149
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• 2023

In geoscience and engineering the geological characteristics of sediment strata is crucial and possible if reliable borehole logging and seismic data are available. To investigate the characteristics of the shallow strata in the Korea Strait, laboratory sonic logs were obtained from deep borehole data and seismic section. In this study, we integrated and analyzed the sonic log data obtained from the drilling core (down to a depth of 200 m below the seabed) and multichannel seismic section. The correlation value was increased from 15% to 45% through time-depth conversion. An initial model of P-wave impedance was set, and the results were compared by performing model-based, band-limited, and sparse-spike inversions. The derived P-impedance distributions exhibited differences between sediment-dominant and unconsolidated layers. The P-impedance inversion process can be used as a framework for an integrated analysis of additional core logs and seismic data in the future. Furthermore, the derived P-impedance can be used to detect shallow gas-saturated regions or faults in the shallow sediment. As domestic deep drilling is being performed continuously for identifying the characteristics of carbon dioxide storage candidates and evaluating resources, the applicability of the integrated inversion will increase in the future.