• Economic and Environmental Geology
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• v.30 no.4
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• pp.303-312
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• 1997

The massive, fractured and porous-type of glauconite, which is subdivided by surface morphology, occur in subtidal sand and semiconsolidated intertidal sand/mud from continental shelf of the southeastern Yellow Sea. This area is presumed to be a part of Holocene transgressive tidal systems tract. The glauconite, pellet-like grains with diameter of 0.1 to 1 mm, is scattered in surface sand sediments. Results of X-ray diffraction data of the minerals are monoclinic with $a=5.242{\AA}$, $b=9.059{\AA}$, $c=10.163{\AA}$, ${\beta}=100.5^{\circ}$, $V=474.53{\AA}^3$. Thermal treatments on the oriented glauconite increase the X-ray diffraction intensity near $10{\AA}$ (001), suggesting the presence of some expandable layers. Specific gravity of the glauconite is $2.60{\pm}0.45gm/cc$ on the basis of chemical composition and unit-cell dimensions. Based on $O_{10}(OH)_2$, chemical composition of glauconites, octahedral Fe content ranges from 1.19 to 2.06 atoms, corresponding octahedral AI is 0.18 to 0.76 atoms, which progressively substitute Fe for AI with increasing from porous to massive-type. The Mg content ranges from 0.35 to 0.54 atoms, and shows higher with increasing Al contents. A systematic increase of interlayer K from 0.34 to 0.71 is also observed with apparent increases from porous to massive-type, and related to a proportion of expandable layers. The clay preserved in glauconite, which is recognized as ordered/disordered (massive to fractured-type). The interstratified illite/smectite (porous-type), contains 7 to 27 % expandable layers. The glauconite seems to originate from post depositional authigenic growth in reducing environments promoted by the dissolution of clay minerals and biogenic debris.

• Geomechanics and Engineering
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• v.13 no.4
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• pp.571-584
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• 2017

Slope mass rating (SMR) is commonly used for the geomechanical classification of rock masses in an attempt to evaluate the stability of slopes. SMR is calculated from the $RMR_{89-basic}$ (basic rock mass rating) and from the characteristic features of discontinuities, and may be applied to slope stability analysis as well as to slope support recommendations. This study attempts to utilize the SMR classification system for slope stability analysis and to investigate the engineering geological conditions of the slopes and the slope stability analysis of the Gas Flare site in phases 6, 7 and 8 of the South Pars Gas Complex in Assalouyeh, south of Iran. After studying a total of twelve slopes, the results of the SMR classification system indicated that three slope failure modes, namely, wedge, plane and mass failure were possible along the slopes. In addition, the stability analyses conducted by a number of computer programs indicated that three of the slopes were stable, three of the slopes were unstable and the remaining six slopes were categorized as 'needs attention'classes.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.904-909
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• 2004

The study area adjoins with Yangsan fault in Sangbuk-myeon, Samsam-ri, Kyongsang-namdo and consist of the natural steep slope. After drawing data layer which have altitude by using digital topography data, it is converted to lattice DEM of $10m{\times}10m$ size. From this, gradient map of unit lattice, slant direction map and shadow relif map are made. Using flow apportioning algorithm, upper slope contributing area and wetness index by established lattice can be calculated. Area that have high wetness index shows lineament structure of northwest-southeast direction, and this agrees with shear fracture system. The result of electricity specific resistance survey in the study area shows that area of high wetness index has low electricity specific resistance anomaly. That is, wetness index conforms with distribution of fractured zone that accompanied chemical weathering of rock. Therefore, wetness index can be used as the method of detecting fractured zones and judging the stability of the area.

• Geomechanics and Engineering
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• v.17 no.2
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• pp.133-143
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• 2019

An optimal hydraulic section is critical for irrigated water conservancy in seasonal frozen ground due to a large proportion of water leakage, as investigated by in-situ surveys. This is highly correlated with the frost heave of underlain soils in cold season. This paper firstly derived a practical model for frost heave of clayey soils, with temperature dependent thermal indexes incorporating phase change effect. A model test carried out on clay was used to verify the rationality of the model. A novel approach for optimizing the cross-section of irrigation canals in cold regions was suggested with live updated geometry characterized by three unique geometric constraints including slope of canal, ratio of practical flow section to the optimal and lining thickness. Allowable frost heave deformation and tensile stress in canal lining are utilized as standard in computation iterating with geometry updating while the construction cost per unit length is regarded as the eventual target in optimization. A typical section along the Jinghui irrigation canal was selected to be optimized with the above requirements satisfied. Results prove that the optimized hydraulic section exhibits smaller frost heave deformation, lower tensile stress and lower construction cost.

• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.607-622
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• 2005

This study was carried out in order to evaluate where the soil loss was mainly occurred, .and to verify how riverbed sediments in the tributaries of the Seomjin River were related to their source rocks distributed in Sunchang area. The study area including the Seomjin River with 4 tributaries of Kyeongcheon, Okgwacheon, Changjeong-cheon and Ipcheon was divided into 10 watershed. The RUSLE (Revised Universal Soil Loss Equation) was estimated for all the grids (10 m cells) in the corresponding watershed. The amount of soil loss per unit area was calculated as follows: dry fold (53,140.94 tons/ha/year), orchard (25,063.38 tons/ha/year), paddy field (6,506.7 tons/ha/year) and Idlest (6,074.36 tons/ha/year). The differences of soil loss per unit area appear to be depends on areas described earlier. Soil erosion hazard zones were generally distributed within dry fields. Several thematic maps such as land use maps, topographical maps and soil maps were used as a data to generate the RUSLE factors. The amount of soil loss, computed by using the RUSLE, showed that soil loss mainly occurred at the regions where possible source rocks were distributed along the stream. Based on the this study on soil loss and soil erosion hazard zone together with chondrite-normalized REE patterns that were previously analyzed in same study area, a closed relationship between riverbed sediments and possible source rocks is formed. Especially in the Okgwacheon that are widely distributed by various rocks, chondrite-normalized REE pattern derived from the riverbed sediments, source rock and soil is expected to have a closed relationship with the distribution of soil loss.

• Journal of the Mineralogical Society of Korea
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• v.5 no.2
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• pp.109-121
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• 1992

For the purpose of mineralogical and chemical study on the topazes from various localities of world(Brzail, China, India, Nigeria and Sri Lanka), electron microprobe analysis(EPMA), neutron activation analysis(NAA), X-ray diffractometry, Raman spectroscopy, etch test, scanning electron microscopy, refractive index, specific gravity, fluid inclusion were performed. The chemical composition in topaz was discussed along with its physical and structural properties. Variations in the unit-cell dimension and physical properties of topaz were found to have a close relations in the unit-cell dimension and physical properties of topaz were found to have a close relationship with extent of substitution of $OH^-\;for\;F^-$. According to neutron activation analyses, the trace elements had no effects on the physical properties of topaz. Raman spectra showed that the peaks of topaz were different in intensity from one locality to another. Etching defects in topaz includes negative crystal defect o point-bottom pit(India, Nigeria) and net work defect of curl-bottom pit(Brazil, China). Fluid inclusions in topaz may be classiffied into liquid $CO_2$-bearing inclusion, gaseous inclusion, halite, sylvite-bearing inclusion and liquid inclusion. The results of this study can be useful to devising artificial coloring methods for topaz with different mineralogical compositions.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.1
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• pp.13-24
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• 2022

The Arctic Ocean is very sensitive to global warming and Arctic Ocean sediments provide a records of terrestrial climate change, analyzing their composition helps clarify global warming. The gravity core sediment ARA07C-St02B was collected at the East Siberian margin during an Arctic expedition in 2016 on the Korean ice-breaking vessel ARAON, and its provenance was estimated through sedimentological, mineralogical and geochemical analysis. The core sediment was divided into four units based on sediment color, sand content and ice-rafted debris content. Units 1 and 3 had higher sand and ice-rafted debris contents than units 2 and 4, and contained a brown layer, whereas units 2 and 4 were mainly composed of a gray layer. Correlation analysis using the adjacent core sediment ARA03B-27 suggested that the sediment units were deposited during marine isotope stage 1 to 4. The bulk mineral, clay mineral, and geochemical compositions of units including a brown layer differed from units including a gray layer. Bulk and clay mineral compositions indicated that coarse and fine sediments had a different origin. Coarse sediments might have been deposited mostly by the East Siberian Coastal Current from the Laptev Sea and the East Siberian Sea or by the Beaufort Gyre from the Chukchi Sea, whereas fine sediments might have been transpoted mostly by currents from the East Siberian Sea, the Chukchi Sea and the Beaufort Sea. Some of the coarse sediments in unit 1 and fine sediments in unit 3 might have been deposited by iceberg ice, sea ice or current from the Beaufort Sea and the Canada Archipelago. Investigating the geochemical composition of the potential origins will elucidate the origin and transportation of the study area's core sediments.

• Economic and Environmental Geology
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• v.55 no.5
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• pp.429-438
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• 2022

This study evaluated the effect of the degree of weathering on the particle size distribution and the amount of fine particles generated in the aggregate production process during the crushing of igneous rock. Rock samples were collected from three areas with differences in strength from the Schmith hammer measurement at the aggregate quarry in Geochang, Gyeongsangbuk-do. After crushing with a jaw crusher under the same conditions in laboratory, particle size analysis, mineral analysis, chemical analysis, and weathering index were calculated. The Schmidt hammer measurements were 56, 28, and <10, and the CIA and CIW values of weathering index were also different, so the rock samples were classified into hard rock, soft rock, and weathered rock according to the weathering degree. It shows a smaller particle size distribution toward weathered rocks under the microscope, and the proportion of altered clay minerals such as sericite increased. The composition of feldspar and quartz was high for hard rock, and the ratio of muscovite and kaolinite was low. As a result of the crushing of the jaw crusher, hard rock produced a lot of coarse crushed material (13.2mm), while soft rock and weathered rock produced fine crushed material (4.75mm). The former showed the characteristics of the beta distribution curve, and the latter showed the bimodal distribution curve. The production of fine rock particles (based on 0.71mm of sieve, wt. %) increased to 13%<21%<22% in hard rock, soft rock, and weathered rock, and the greater the degree of weathering, the more fine rock particles were generated. The fine particles are recovered by the operation of the sand unit in the wet aggregate production process. Therefore, in order to minimize the amount of sludge generated in the aggregate production process, it was judged that a study on the optimal operation of cyclones could be necessary.

• Economic and Environmental Geology
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• v.34 no.1
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• pp.1-12
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• 2001

The crystal structure of biotite-1M from Bancroft, Ontario, was determined by Rietveld refinement method using high-resolution neutron powder diffraction data at -26.3$^{\circ}C$, 2$0^{\circ}C$, 30$0^{\circ}C$, $600^{\circ}C$, 90$0^{\circ}C$. The crystal structure has been refined to a R sub(B) of 5.06%-11.9% and S (Goodness of fitness) of 2.97-3.94. The expansion rate of a, b, c unit cell dimensions with elevated temperature linearly increase to $600^{\circ}C$. The expansivity of the c dimension is $1.61{\times}10^{40}C^{-1}$, while $2.73{\times}10^{50}C^{-1}$ and $5.71{\times}10^{-50}C^{-1}$ for the a and b dimensions, respectively. Thus, the volume increase of the unit cell is dominated by expansion of the c axis as increasing temperature. In contrast to the trend, the expansivity of the dimensions is decreased at 90$0^{\circ}C$. It may be attributed to a change in cation size caused by dehydroxylation-oxidation of $Fe^{2+}$ to $Fe^{3+}$ in vacuum condition at such high temperature. The position of H-proton was determined by the refinement of diffraction pattern at low temperature (-2.63$^{\circ}C$). The position is 0.9103${\AA}$ from the O sub(4) location and located at atomic coordinates (x/a=0.138, y/b=0.5, z/c=0.305) with the OH vector almost normal to plane (001). According to the increase of the temperature, $\alpha$* (tetrahedral rotation angle), $t_{oct}$ (octahedral sheet thickness), mean distance increase except 90$0^{\circ}C$ data. But the trend is less clearly relative to unit cell dimension expansion because the expansion is dominant to the interlayer. Also, ${\Psi}$ (octahedral flattening angle) shows no trends as increasing temperature and it may be because the octahedron (M1, M2) is substituted by Mg and Fe.

• The Journal of Engineering Geology
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• v.21 no.2
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• pp.133-145
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• 2011

Unsaturated soil column tests were performed for weathered gneiss soil and weathered granite soil to assess the relationship between infiltration velocity and rainfall condition for different rainfall durations and for multiple rainfall events separated by dry periods of various lengths (herein, 'rainfall break duration'). The volumetric water content was measured using TDR (Time Domain Reflectometry) sensors at regular time intervals. For the column tests, rainfall intensity was 20 mm/h and we varied the rainfall duration and rainfall break duration. The unit weight of weathered gneiss soil was designed 1.21 $g/cm^3$, which is lower than the in situ unit weight without overflow in the column. The in situ unit weight for weathered granite soil was designed 1.35 $g/cm^3$. The initial infiltration velocity of precipitation for the two weathered soils under total amount of rainfall as much as 200 mm conditions was $2.090{\times}10^{-3}$ to $2.854{\times}10^{-3}$ cm/s and $1.692{\times}10^{-3}$ to $2.012{\times}10^{-3}$ cm/s, respectively. These rates are higher than the repeated-infiltration velocities of precipitation under total amount of rainfall as much as 100 mm conditions ($1.309{\times}10^{-3}$ to $1.871{\times}10^{-3}$ cm/s and $1.175{\times}10^{-3}$ to $1.581{\times}10^{-3}$ cm/s, respectively), because the amount of precipitation under 200 mm conditions is more than that under 100 mm conditions. The repeated-infiltration velocities of weathered gneiss soil and weathered granite soil were $1.309{\times}10^{-3}$ to $2.854{\times}10^{-3}$ cm/s and $1.175{\times}10^{-3}$ to $2.012{\times}10^{-3}$ cm/s, respectively, being higher than the first-infiltration velocities ($1.307{\times}10^{-2}$ to $1.718{\times}10^{-2}$ cm/s and $1.789{\times}10^{-2}$ to $2.070{\times}10^{-2}$ cm/s, respectively). The results reflect the effect of reduced matric suction due to a reduction in the amount of air in the soil.