• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.543-551
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• 2015

Quick-hardening track (QHT) is a construction method which is used to change from old ballast track to concrete track. Sufficient time for construction is important, as the construction should be done during operational breaks at night. Most of the time is spent on exchanging the ballast layer. If it is possible to apply the ballast non-exchange type of quick-hardening track, it would be more effective to reduce the construction time and costs. In this paper, pouring materials with high permeability are suggested and a construction method involving a layer separation pouring process considering the void condition is introduced in order to develop ballast non-exchange type of QHT. The separate pouring method can secure the required strength because optimized materials are poured into the upper layer and the lower layer for each void ratio condition. To ensure this process, a rheology analysis was conducted on the design of the pouring materials according to aggregate size, the aggregate distribution, the void ratio, the void size, the tortuosity and the permeability. A polymer series was used as the pouring material of the lower layer to secure the void filling capacity and for adhesion to the fine-grained layer. In addition, magnesium-phosphate ceramic (MPC) was used as the pouring material of the upper layer to secure the void-filling capacity and for adhesion of the coarse-grained layer. As a result of a mechanics test of the materials, satisfactory performance corresponding to existing quick-hardening track was noted.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.4
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• pp.179-191
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• 2018

In order to determine the distribution characteristics of the heavy metals in surface sediments of the eastern Yellow Sea, heavy metal concentrations (Cu, Pb, Zn, Cd, Cr, Mn, As, Ni, Co, Li, Fe and Al) together with grain size and total organic carbon (TOC), were analyzed. The concentrations of all heavy metals, with the exception of Pb, Mn and As in some stations, were relatively high in the central area of the Yellow Sea and tended to decrease toward the Korean coast. A significant relationship between grain size and concentrations of heavy metals suggested that they were mostly controlled by quartz dilution effect. However, at some stations, Pb, Mn and As exhibited different distribution patterns. For Pb, the differences were caused by petrogenetic influences (feldspar) in coarse-grained sediments. In the case of Mn, biogenetic influences ($CaCO_3$) affected distribution patterns. As was distributed differently because of the existence of a heavy mineral (pyrite). A comparison with previous data (collected in 2000) shows that the heavy metal concentration in the eastern Yellow Sea has not increased over the past fifteen years. The sedimentary environment of dumping sites in the Yellow Sea has not been significantly improved during this period. The results of the pollution assessment revealed that the concentrations of heavy metals in the study area were lower than lower criteria (TEL, MSQ-1) in Korean and Chinese sediment quality guidelines. The enrichment factor (EF), geo-accumulation index ($I_{geo}$) and ecological risk index (ERI) of Cu, Pb, Zn and Cr were higher in the central area of the Yellow Sea.

• Journal of The Geomorphological Association of Korea
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• v.15 no.2
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• pp.11-24
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• 2008

Stratified slope was formed on the SSE-facing slope in the southwest region of Haenam, South Korea. Field and laboratory investigations into the geomorphology and sedimentology of stratified slope deposit that is inactive. Outcrops of this deposit show an alteration of coarse debris-supported matrix and tiny debris-supported matrix layers. Sedimentological analysis(particle-size analysis) indicates that this deposit is not fluvial process or only gravitation like rock-fall. Many clasts and fine materials on the slope is supposed to be product by congelifraction under Pleistocene periglacial climatic environment. Also The processes responsible for the genesis of this deposit probably are to move downward by gelifluction and to remove fine materials by slope wash in thawing cycle and in situ debris congelifraction on gelifluction slope. Now It is impossible to account for the time range of genesis(diurnal, seasonal). In conclusion, this stratified slope formed in cold and humid periglacial environmental in pleistocene, therefore, this slope is a periglacial relic landform, indicates that in south korea there was a cold and humid paleo-climate such as periglacial environmen.

• Journal of the Korean earth science society
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• v.42 no.2
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• pp.164-174
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• 2021

The study examines the shearing and crushing characteristics of land-derived subaqueous granular materials in a gravel-bed river. A series of large-sized ring shear tests were performed to examine the effect of shear time and shear velocity on the shear stress characteristics of aquarium gravels with a 6-mm mean grain size. Three different shear velocities (i.e., 0.01, 0.1, and 1 mm/sec) were applied to measure the shear stress under the drained (long-term shearing) and undrained (short-term shearing) conditions. Different initial shear velocities, i.e., 0.01→0.1→1 mm/sec and 0.1→0.01→1 mm/sec, were considered in this study. The test results show that the grain crushing effect is significant regardless of drainage conditions. The shear stress of coarse-grained materials is influenced by initial shear velocities, regardless of the drainage conditions. In particular, particle breakage increases as grain size increases. The shearing time and initial shear velocity are the primary influencing factors determining the shear stress of gravels. The granular materials may be broken easily into particles through frictional resistance, such as abrasion, interlocking and fracture due to the particle-particle interaction, resulting in the high mobility of granular materials in a subaqueous environment.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.141-155
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• 2023

Monitoring technology based on electrical resistivity is widely used for non-destructive data collection and health analysis of underground structures and tunnels. Vulnerable sections such as fault zone generates many problems during construction of the tunnel. These problems cause displacement and stress changes of the ground. Therefore, it is necessary to predict the state of the fault zone section to ensure the mechanical stability of the underground structure. Monitoring the size of joints and the porosity of the fillings is essential for rocks. Previous studies have not considered the variety of fillings in rock joints. In this study, electrical resistivity tests were conducted according to the particle mixing state of the sandy fillings. When the size of fillings is decreased at the constant porosity, the electrical resistivity tends to increase. The results of this study are expected to be useful as basic electrical resistivity data for predicting the ground conditions and evaluation of the ground behavior that is containing sandy fillings in the rock joint for tunnels.

• Journal of the Korean Geographical Society
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• v.42 no.4
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• pp.469-487
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• 2007

Grain-Size Trend Analysis is the methodology to identify net sediment transport pathways, based on the assumption that the movement of sediment from the source to deposit leaves the identifiable spatial pattern of mean, sorting, and skewness of grain size. It can easily be implemented with low cost, so it has great potentials to contribute to geomorphological research, whereas it can also be used inadequately without recognition of its limitations. This research aims to compare three established methods of grain-size trend analysis to search for the adequate way of application, and also suggest the research tasks needed in improving this methodology 1D pathway method can corporate the field experience into analyzing the pathway, provide the useful information of depositional environments through X-distribution, and identify the long-term trend effectively. However, it has disadvantage of the dependence on subjective interpretation, and a relatively coarse temporal scale. Gao-Collins's 2D transport vector method has the objective procedure, has the capability to visualize the transport pattern in 2D format, and to identify the pattern at a finer temporal scale, whereas characteristic distance and semiquantitative filtering are controversial. Le Roux's alternative 2D transport vector method has two improvement of Gao-Collins's in that it expands the empirical rules, considers the gradient of each parameters as well as the order, and has the ability to identify the pattern at a finer temporal scale, while the basic concepts are arbitrary and complicated. The application of grain sire trend analysis requires the selection of adequate method and the design of proper sampling scheme, based on the field knowledge of researcher, the temporal scale of sediment transport pattern targeted, and information needed. Besides, the relationship between the depth of sample and representative temporal scale should be systematically investigated in improving this methodology.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.4
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• pp.179-187
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• 1980

1) Soils (volcanic ash and muck) were fractionated into particle-size separates (200 - 20, 20 - 2, 2 - 0.5 and finer than $0.5{\mu}$ in diamter), and of which the silt fraction was further fractionated into specific gravity separates (more than 2.0, 2.0 - 1.7, 1.7 - 1.4 and less than 1.4 in $g/cc^3$). And total organic and inorganic phosphorus in the separates were determined. 2) The amounts of total, organic and inorganic phosphorus distributed in the particle-size separates were as follows fine clay > coarse clay > silt > fine sand fraction. The increase rate in the amounts of phosphorus was great in the separates finer than $20{\mu}$, and greatest in the fine clay fraction. 3) The amounts of total, oganic and inorganic phosphorus distributed in the specific gravity separates were as follows: 2.0 - 1.7 > 1.7 - 1.4 > heavier than 2.0 fraction. The increase rate in the amounts of phosphorus was in the following order 2.0 - 1.7 > 1.7 - 1.4 > heavier than 2.0 fraction. 4) Distribution of carbon, amorphous aluminum and free iron oxides in the particle-size separates and the specific gravity separates were examined, and the distribution and the formes of organo-minera1 complexes in the separates were discussed to shed light on the factors affecting the distribution of phosphorous into the separates. And it was estimated that there was close relation among the distribution of organic and inorganic phosphorus, and the distribution and the formes of organo-minera1 complexes.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.739-752
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• 2006

Deep-sea surface sediments acquired by multiple corer from 69 stations in the Clarion-Clipperton fracture zone of the northeast equatorial Pacific, were examined to understand the correlation of mass physical properties and sedimen-tological processes. The seabed of the middle part ($8-12^{\circ}N$) of the study area is mainly covered by biogenic siliceous sediment compared with pelagic red clays in the northern part ($16-17^{\circ}N$). In the southern part ($5-6^{\circ}N$), water depth is shallower than carbonate compensation depth (CCD). The mass physical properties such as grain size distribution, mean grain size, water content, specific grain density, wet bulk density, void ratio, and porosity of sediments are distinctly different among the three parts of the study area. Surface sediments in northern part are characterized by fine grain size and low water contents possibly due to low primary productivity and high detrital input. Conversely, sediments in the middle part are characterized by coarse grain size and high water contents, which might be caused by high surface productivity and deeper depth than CCD. The sediments show low water contents and high density in the southern part, which can be explained by shallower depth than CCD. Our results suggest that the variations in mass physical properties of sediments are influenced by combined effects including biogenic primary productivity of surface water, water depth, especially with respect to CCD, sedimentation rate, detrital input, and the geochemistry of the bottom water (for example, formation of authigenic clay minerals and dissolution of biogenic grains).

• 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.

• The Journal of the Petrological Society of Korea
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• v.21 no.2
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• pp.263-275
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• 2012

Jurassic Daebo biotite granites, known as one of the main stone resources in the country, are widely and away distributed in the Pocheon and Yangju areas of the mid Gyeonggi massif. The objects of the study are mainly to reveal the unique characteristics of grain size, rock color, mineral composition, physical property and fracture system from the above biotite granites. Biotite granites from the Pocheon area (PG) and Yangju area (YG) are represented by coarse-grained and light gray, and medium to coarse-grained and grayish to light gray, respectively. In modes, main minerals of Qz+Af+Pl (quartz+alkali feldspar+plagioclase) are more increased in the PG, and accessories of biotite are more increased in the YG, which differences can cause the PG more bright light gray than the YG. Specific gravity (SG) shows somewhat more increasing in the YG than the PG. These differences can be caused by more increasing in biotite contents of higher specific gravity compared to the major minerals in the former than the latter. Absorption ratio (AR) and porosity (PR) of the PG and YG show the same values of 0.33 % and 0.86 %, respectively. In the correlations, PR vs SG and AR vs PR show gradually negative and distinctly positive trends, respectively. Compressive strength (CS) and tensile strength (TS) show increasing in the PG (CS: 1,775 $kg/cm^2$, TS: 87 $kg/cm^2$) than the YG (CS: 1,647 $kg/cm^2$, TS: 79 $kg/cm^2$). These strength characteristics could be attributed to the inherent rock textures of them. Abrasive hardness (AH) also shows a little increasing in PG, which can be caused by increase in quartz contents having higher hardness than the other major minerals. Orientations of fracture sets from the PG and YG were compared with those of vertical rift and grain planes in Mesozoic granites of the country. From the overlapped diagram, the distribution pattern between fracture sets and above vertical planes suggests that microcrack systems developed in Mesozoic granites in Korea occur also in the Daebo biotite granite bodies of the mid Gyeonggi massif. From the relation diagram showing the characteristics of fracture patterns for the above two area, PG and YG may have more potentiality for dimension and non-dimension stone resources, respectively.