• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.61-71
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• 1993

The stress waves generated by the mechanical energies by impact or the chemical energies by the explosions are transmitted through medium. The wave propagation process through medium is a very complicated procedure due to the reflections and refractions of the waves at the free surfaces and interfaces. In this study the pressure independent Von-Mises model is employed for the wave propagation analysis in the layered systems. Governing equations of this study are conservation equations of momentum and mass in Lagrangian coordinate system which is fixed to the material. Due to the shock-front which violates the continuity assumptions inherent in the differential equations numerical artificial viscosity is used to spread the shock front over several computational zones. These equations are solved by Finite Difference Method with discretized time and space coordinates. The associate normality flow rule as a plastic theory is implemented to find the plastic strains.

• The Journal of Engineering Geology
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• v.22 no.3
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• pp.353-363
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• 2012

The geology of Ulleung-Do is dominated by volcanic rocks with low strength and trachytic rocks with high strength but containing vertical joints that yield easily. Consequently, rockfalls along roadcuts are a major geological hazard, with the potential to affect the ring road of Ulleung-Do. In this study, we performed three types of rockfall hazard-risk assessment on the 3-km-long section of the ring road expected to have the highest possibility of rockfall. We used a rockfall ranking sheet in a roadside landslide hazard map, the Slope Stability Inspection Manual for National Highways (Japan), and a rockfall hazard rating system for inspection from the Japan Highway Public Corporation. We also employed the evaluation criteria of 'RHRS' developed by the Federal Highway Administration (FHA). An analysis of roadcuts at 27 sites with regard to geographic and geological conditions resulted in the identification of three classes of rockfall hazard (high, medium, and low). Of note, over 74% of slopes were assessed as high- and medium-class. Finally, a rockfall hazard map of the northeast region of Ulleung-Do was produced based on the evaluation results.

• Tunnel and Underground Space
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• v.23 no.4
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• pp.261-270
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• 2013

As part of the development of the 3-D geologic modeling software, this study addresses on new development of software modules that can perform the analysis and visualization of the fracture network system in 3-D. The developed software modules, such as BOUNDARY, DISK3D, FNTWK3D, CSECT and BDM, are coded on Microsoft Visual Studio platform using the MFC and OpenGL library supported by C++ program language. Each module plays a role in construction of analysis domain, visualization of fracture geometry in 3-D, calculation of equivalent pipes, production of cross-section map and management of borehole data, respectively. The developed software modules for analysis and visualization of the 3-D fracture network system can be used to tackle the geomechanical problems related to strength, deformability and hydraulic behaviors of the fractured rock masses. All these benefits will further enhance the economic competitiveness of the domestic software industry.

• Journal of the Korean Geographical Society
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• v.47 no.6
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• pp.809-824
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• 2012

Stone cultural heritages quantitatively as well as qualitatively occupy a large proportion in the designated heritages in Korea. The Stone Buddha statue in the Gulbulsa temple site, designated as the No. 121 treasure in 1935, is located in the southwestern slope of Mt. Sogeumgang, Dongcheon-dong, Gyeongju-si, Gyeongbuk Province and Buddhist images are sculptured on four sides of a 3.5m-tall gigantic rock. The damage states result from the weathering degree and indicate high correlation with the water contents. The water contents in the Stone Buddha of Gulbulsa temple site are highest at the east side and then decrease in order of north, south and west sides. These are proportional to the durations of sunshine. Moreover, the Stone Buddha of Gulbulsa temple site with dense joints, repaired areas and vegetated areas by lichens shows high water contents and damage states.

• Tunnel and Underground Space
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• v.17 no.1 s.66
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• pp.32-42
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• 2007

Severe damage can occur around deposition holes due to complex interaction of thermo-hydro-mechanical (THM) loading during the long term operation of high level radioactive waste repository. Many candidate sites for repository are located in crystalline rock mass, therefore mechanism of damage follows the form of brittle fracture and failure. This paper briefly introduces major outcomes from 15 years international collaborative project, DECOVALEX, and presents major study results for current ongoing benchmark test study from DECOVALEX-THMC, to evaluate the effect of THM loading to rock mass in excavation damaged zone (EDZ) near deposition holes. Through benchmark test model by simplifying THM loading to boundary loading obtained numerical results are compared, and discrete fracture interaction after up to 1 million years operation is discussed.

• 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.

• Journal of the Korean Geotechnical Society
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• v.24 no.10
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• pp.25-32
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• 2008

Based on recent studies, the side resistance of rock socketed drilled shafts was affected by unconfined compressive strength of rock, socket roughness, rock types and joints, and initial normal stress. Especially, the socket roughness was affected by rock types and joints, drilling methods, and diameters of pile. In this study, a new roughness measurement system (BKS-LRPS, Backyoung-KyungSung Laser Roughness Profiling System) usable in water was developed. Based on the laboratory model tests, an EMD (Effective Measurement Distances) according to various turbidity was proposed as $EMD=1149.2{\times}T_{b}^{-0.64}$.

• Journal of the Korean Geotechnical Society
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• v.25 no.8
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• pp.5-21
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• 2009

Based on recent studies on rock socketed drilled shafts, it was found that the side resistance of rock socketed drilled shafts is affected by unconfined compressive strength of rock, socket roughness, rock types and joints, and initial normal stress. Especially, the socket roughness is affected by rock types and joints, drilling methods, and diameters. Since existing roughness measurement systems could be conducted only in the air, a new roughness measurement system, which can measure rock socket roughness in the air and also in the water, is needed. However, the development of new roughness measurement system fur civil engineers has been faced with difficulties of electrical applications. In this study, the laboratory verification system far BKS-LRPS (Backyoung-KyungSung Laser Roughness Profiling System) was developed, which can be applied both in the water and air. Based on the laboratory verification, it was found that the improved BKS-LRPS could define effective measurement distances for the conditions reflecting the apparatus and in-situ situations.

• Journal of the Korean earth science society
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• v.44 no.6
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• pp.611-628
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• 2023

This study aimed to explore the geo-educational value of Deokmyeong-ri in Goseong-gun, Gyeongsangnamdo, through field research. The study area comprises well-exposed outcrops, which can be used as field sites during field trip for studying sedimentary structures (normal grading bedding, cross bedding, ripple, and desiccation crack), coastal depositional environments (coastal cliff, shore platform, and gravel beach), basic principles of relative dating (unconformity, fault, intrusion, and xenolith), and columnar joints. This study evaluated the field sites based on the achievement standards and textbooks used in the science curriculum. The field sites have a high educational value because they exhibit typicality, as mentioned in the textbook, and provide study materials for enrichment learning. Furthermore, Deokmyeong-ri Area has well-developed tourist and educational infrastructures; thus, it is a safe place for geological education.

• 한국지구물리탐사학회:학술대회논문집
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• 1999.08a
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• pp.137-155
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• 1999

Recently, Televiewer(Borehole Acoustic Scanner(Televiewer)) has come to be widely used specially for the general engineering construction design. The Televiewer tool using a focussed acoustic beam is to detect the amplitude and traveltime of each reflected acoustic signal at the wall, resulting in the amplitude- and traveltime image respectively. Fractures can be well detected, because they easily scatter the acoustic energy due to the highly narrow beam. In addition, the drilling work will rough the borehole wall so that the acoustic energy can be scattered simply due to the roughness of the wall. Thus, the amplitude level can be directed associated with the elastic properties(impedance) and the hardness of the rock as well. Meanwhile, the traveltime image provides an information about the borehole shape and can be converted to a high precision 3D caliper log(max. 288 arms). In this paper, based on the high resolution of Televiewer images, general evaluation methods are illustrated to derive very reliable rock parameters.