• The Journal of Engineering Geology
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• v.11 no.2
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• pp.205-214
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• 2001

A simple automated measuring method for planar or linear features on the rock excavation surface is presented. Attitude of the planar and linear feature is calculated from 3D coordinates of points on the structures. Spatial coordinates are calculated from overlapped stereo images. Factors used in the calculation are (1) local coordinates of the left and right images, (2) the focal length of cameras, and (3) the distance between two cameras. A simple image capturing device and an image treatment routine coded by Visual Basic and GIS components are constructed for the remote measurements, The methodology shows less than 1 cm error when a point is measured from 179 cm in distance. The methodology is tested at the excavation site in PaiChai University. Remotely measured result matches well with the manual measurement within the reasonable error range.

• Geomechanics and Engineering
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• v.11 no.6
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• pp.821-845
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• 2016

Extensive researches on distribution of earthquake induced damages in different regions have shown that geological and geotechnical conditions of the local soils significantly influence behavior of alluvial areas under seismic loading. In this article, the site of Babol city which is formed up of saturated fine alluvial soils is considered as a case study. In order to reduce the uncertainties associated with earthquake resistant design of structures in this area (Babol city), the required design parameters have been evaluated with consideration of site's dynamic effects. The utilized methodology combines experimental ground ambient noise analysis, expressed in terms of horizontal to vertical (H/V) spectral ratio, with numerical one-dimensional response analysis of soil columns using DEEPSOIL software. The H/V spectral analysis was performed at 60 points, experimentally, for the region in order to estimate both the fundamental period and its corresponding amplification for the ground vibration. The investigation resulted in amplification ratios that were greater than one in all areas. A good agreement between the proposed ranges of natural periods and alluvial amplification ratios obtained through the analytical model and the experimental microtremor studies verifies the analytical model to provide a good engineering reflection of the subterraneous alluviums.

• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2576-2581
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• 2021

The thermal stability and crystallization behaviors of La₂O₃ containing B₂O₃-CaO-Al₂O₃ glass waste forms were investigated to evaluate the stability of waste form during emergencies in deep geological disposal. For glasses containing 15% La₂O₃, LaBO₃ phases were observed as major crystals from 780 ℃ and exhibited needlelike structures. Al, Ca, and O were homogeneously distributed throughout the entire specimen, while some portions of B and La were concentrated in some parts. By differential thermal analysis at various heating rates, the activation energy for grain growth and the crystallization rate of LaBO₃ were calculated to be 12.6 kJ/mol and 199.5 kJ/mol, respectively. These values are comparable to other waste forms being developed for the same purpose.

• Steel and Composite Structures
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• v.38 no.1
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• pp.79-86
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• 2021

Due to the complex geological conditions, a large number of high quality coal seams was buried in the western of China which cannot be mining in open-pit methods. The dynamic properties of that coal cannot be studied easily in real site for the complex working condition. The compound coal blocks made on the basis of the real situation were studied in the laboratory. The physical and mechanical properties of the compound coal blocks and the raw coal were contrasted by using the UCS tests. The results show that the compound coal blocks made by mixing coal powder, cement and water in proportion of 2.5:2:1 are the closest to that of standard raw coal. Then the propagation of strain waves and crushing effects on the coal were studied in the compound coal blocks by using the super dynamic strain test system and the numerical calculated method of ANSYS/LS-DYNA. The results show that the diameter of the crushing zone in the compound coal blocks was similar to that in the numerical results. The fractures distribution in laboratory tests also has a similar trend to the calculation results. The measured strain waves at the distance of 50 cm, 100 cm, and 150 cm from the center of the charge are mainly concerned at -1.0×104 με and have a similar trend as that in the numerical simulation.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.3
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• pp.157-162
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• 2023

As a result of active geological investigation of faults in Korea, many Quaternary faults have been identified and some of them were judged to have potential to generate earthquakes. Those faults need to be considered as additional seismic sources in the seismic hazard analysis. When a fault is introduced as a new source, the earthquakes generated by the fault should be removed from the area sources that include any part of the fault, to avoid double counting. In practice, however, double counting cannot completely be avoided as the complete separation of the fault-generated earthquakes from the area sources is impossible due to uncertainties related to the earthquake location, subsurface structures of faults, etc. When a new fault source is introduced, the only constraint is the invariance of earthquake frequency. The maximum earthquake and the Richter-b value should also be subject to change, but there are no competent approaches to estimate the change due to incomplete separation of earthquakes. To gain insight into the effect of a new fault source, an example calculation of the seismic hazard were carried out. The example calculation shows that addition of a new fault source centers seismic hazard around the fault source.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.133-140
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• 2007

DCM (Deep Cement Mixing Method) has been applied to build structures such as self-supported earth retaining walls. DCM columns should be penetrability into the stiff layer to assure the self-supporting ability. On the penetration increase of blade attached to the DCM mixing tools, a spiral mixing blade has been revised. Penetration characteristics of spiral blades in the stiff soil layer were evaluated through Gimhae and Incheon areas. The spiral mixing blades could penetrate into the stiff soil layers which have the N-value of greater than 30 although the penetration rate is somewhat slow. Penetration characteristics and economical efficiency should be discussed to determine the critical depth of the spiral mixing blade because the penetration efficiency can decrease in the stiff layer in this paper.

• Economic and Environmental Geology
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• v.45 no.1
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• pp.31-40
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• 2012

This paper examined the characteristics of ductile and brittle structural elements with detailed mapping by lithofacies classification to clarify the relationship between the geological structure and the geochemical high-grade uranium anormal zone and to provide the basic information on the flow of groundwater in the eastern area of Shinbo mine, Jinan-gun, Jeollabuk-do, Korea. It indicates that this area is mainly composed of Precambrian quartzite, metapelite, metapsammite, which show a zonal distribution of mainly ENE-WSW trend, and age unknown pegmatite and Cretaceous porphyry which intrude them. But the Cretaceous Jinan Group which unconformably covers them, contrary to assumption, could not be observed. The main ductile deformation structures of Precambrian metasedimentary rocks were formed at least through three phases of deformation [ENE striking regional foliation (D1) -> ENE or EW striking crenulation foliation (D2) -> WNW or EW trending open, tight, kink folds (D3)]. The predominant orientation of S1 regional foliation strikes ENE and dips south, being similar to the zonal distribution of Precambrian metasedimentary rocks. Most predominant orientation of high-angled brittle fracture (dip angle ${\geq}45^{\circ}$) [ENE (frequency: 24.3%) > NS (23.9%) > (N)NW (18.8%) > WNW (16.9%) > NE (16.1%) fracture sets in descending frequency order], which is closely related to the flow of groundwater, strikes ENE and dips south. It also agrees with the zonal distribution of metasedimentary rocks and the predominant orientation of S1 regional foliation. The next one strikes NS and dips east or west. Considering the controlling factor of the geochemical uranium anormal zone in the Shinbo mine and its eastern areas from the above structural data. the uranium source rock in these areas might be pegmatite and the geochemical uranium anormal zone in the Sinbo mine area could be formed by an secondary enrichment through the flow of pegmatite aquifer's groundwater into the Sinbo mine area like the previous research's result.

• The Korean Journal of Petroleum Geology
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• v.2 no.2 s.3
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• pp.59-70
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• 1994

The Cenozoic geological structures and the tectonic evolution of the southern Ulleung Basin were studied with seismic profiles and exploration well data. Basement structure of the Korea Strait is distinctly characterized by normal faults trending northeast to southwest. The normal faults of the basement are most likely related to the initial liking and extensional tectonics of Ulleung Basin. Tsushima fault along the west coast of Tsushima islands runs northeastward to the central Ulleung Basin. The Middle Miocene and older sequences in the Tsushima Strait show folds and faults mostly trending northeast to southwest. These folds and faults may be interpreted as a result of compressional tectonics. The Late Miocene to Qauternary sequences are not much deformed, but numerous faults mostly N-S trending are dominated in the Tsushima Strait. The Ulleung Basin was in intial rifting during Oligocene, and then active extension and subsidence from Early to early Middle Miocene. Therefore SW Japan separated from Korea Peninsula and drifted toward southeast, and Ulleung Basin was formed as a pull-apart basin under dextral transtensional tectonic regime. During rifting and extensional stage, Tsushima fault as a main tectonic line separating SW Japan block from the Korean Peninsula acted as a normal faulting with right-lateral strike-slip motion as SW Japan drifted southeastward. During middle Middle Miocene to early Late Miocene, the opening of Ulleung basin stopped and uplifted due to compressional tectonics. The southwest Japan block converging on the Korean Peninsula caused compressional stress to the southern margin of Ulleung Basin, resulting in strong deformation under sinistral transpressional tectonic regime. Tsushima fault acted as thrust fault with left-lateral strike-slip motion. From middle Late Miocene to Quaternary, the southern margin of Ulleung Basin has been controlled by compressional motion. Thus the Tsushima fault still appears to be an active thrust fault by compressional tectonic regime.

• The Journal of the Petrological Society of Korea
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• v.28 no.1
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• pp.25-38
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• 2019

The Muju-Seolcheon area, which is known to be located in the boundary of Ogcheon Belt and Ryeongnam Massif (OB-RM), consists of age unknown or Precambrian metamorphic rocks (MRs) [banded biotite gneiss, metasedimentary rocks (black phyllite, mica schist, crystalline limestone, quartzite), granitic gneiss, hornblendite], Mesozoic sedimentary and igneous rocks. In this paper are researched the structural characteristics of each deformation phase from the geometric and kinematic features and the developing sequence of multi-deformed rock structures of the MRs, and is considered the boundary location of OB-RM with the previous geochemical, radiometric, structure geological data. The geological structure of this area is at least formed through four phases (Dn-1, Dn, Dn+1, Dn+2) of deformation. The Dn-1 is the deformation which took place before the formation of Sn regional foliation and formed Sn-1 foliation folded by Fn fold. The Dn is that which formed the Sn regional foliation. The predominant Sn foliation shows a NE direction which matches the zonal distribution of MRs. A-type or sheath folds, in which the Fn fold axis is parallel to the direction of stretching lineation, are often observed in the crystalline limestone. The Dn+1 deformation, which folded the Sn foliation, took place under compression of NNW~NS direction and formed Fn+1 fold of ENE~EW trend. The Sn foliation is mainly rearranged by Fn+1 folding, and the ${\pi}$-axis of Sn foliation, which is dispersed, shows the nearly same direction as the predominant Fn+1 fold axis. The Dn+2 deformation, which folded the Sn and Sn+1 foliations, took place under compression of E-W direction, and formed open folds of N-S trend. And the four phases of deformation are recognized in all domains of the OB-RM, and the structural characteristics and differences to divide these tectonic provinces can not be observed in this area. According to the previous geochemical and radiometric data, the formation or metamorphic ages of the MRs in and around this area were Middle~Late Paleproterozoic. It suggests that the crystalline limestone was at least deposited before Middle Paleproterozoic. This deposition age is different in the geologic age of Ogcheon Supergroup which was recently reported as Neoproterozoic~Late Paleozoic. Therefore, the division of OB-RM tectonic provinces in this area, which regards the metasedimentary rocks containing crystalline limestone as age unknown Ogcheon Group, is in need of reconsideration.

• The Journal of Engineering Geology
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• v.7 no.3
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• pp.173-189
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• 1997

A study on the geological structure and geothermal gradient distribution was carried out to evaluate the feasibility of developing a new geothermal field in the Yusong area. It is suggested that geothermal water in the Yusong area is closely related with faults, dykes, and their dipping characteristics with the study of geothermal gradient distribution. A fault of EW direction locates in northern boundary of the study area and another fault of N40{\citc}W$ crosses the EW fault at the western part of the study area. Locations of faults are recognized quite well by lineaments, geophysical exploration and geothermal gradient distribution characteristics. Three sets of dyke are found in the study area. According to the result of the geothermal gradient distribution study, the location of geothermal anomaly belt and dykes coincide each other, and the area has the temperature gradient of larger than 3$^{\circ}C$ between the depths of 0.5m and 1.0m below ground surface. The thermal anomaly belt those temperature gradient is larger than 2.5$^{\circ}C$ between the depths of 0.5m and 1.Om below ground surface is expected in the direction of N80{\citc}W$ in the study area. The dirping of dyke is almost vertical according to the linear distribution of dykes on surface and the results of geophysical survey. From the distribution of geothermal anomaly belt and the locations of dyke, three locations for the development of hot spring water could be recommended and the depth that ensure over 4$0^{\circ}C$ geotheraral water is estimated as 170~200m below the ground surface.