• The Journal of the Petrological Society of Korea
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• v.27 no.2
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• pp.85-96
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• 2018

The Neoproterozoic Gyemyeongsan Formation and the Mesozoic igneous rocks are distributed in the Eoraesan area, Chungju which is located in the northwestern part of Ogcheon metamorphic zone, Korea, and the rare earth element (REE) mineralized zone has been reported in the Gyemyeongsan Formation. We drew up the detailed geological map by the lithofacies classification, and measured the radioactivity values of the constituent rocks to understand the distribution and characteristics of the source rocks of REE ore body in this paper. It indicates that the Neoproterozoic Gyemyeongsan Formation is mainly composed of metapelitic rock, granitic gneiss, iron-bearing quartzite, metaplutonic acidic rock (banded type, fine-grained type, basic-bearing type, coarse-grained type), metavolcanic acidic rock, and the Mesozoic igneous rocks, which intruded it, are divided into pegmatite, biotite granite, gabbro, diorite, basic dyke. The constituent rocks of Gyemyeongsan Formation show a zonal distribution of mainly ENE trend, and the distribution of basic-bearing type of metaplutonic acidic rock (MPAR-B) is very similar to that of the previous researcher's REE ore body. The Mesozoic biotite granite is regionally distributed unlike the result of previous research. The radioactive value of MPAR-B, which has a range of 852~1217 cps (average 1039 cps), shows a maximum value among the constituent rocks. The maximum-density distribution of radioactive value also agrees with the distribution of MPAR-B. It suggests that the MPAR-B could be a source rock of the REE ore body.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.380-385
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• 2014

Spherical atomizing reduction steel slag was prepared by atomizing technology using reduction steel slag (ladle furnace slag, LFS) generated from steel industry. In order to develop the mass-recycling technology of atomizing reduction steel slag, polymer concrete composite was prepared using spherical atomizing reduction steel slag instead of fine aggregate (river sand) and coarse aggregate (crushed aggregate), depending on the grain size. Different polymer concrete specimens were prepared with the various proportions of polymer binder and replacement ratios of atomizing reduction steel slag in order to investigate the characteristics of polymer concrete composite. Results showed that compressive strengths of polymer concrete specimens decreased with the increase of replacement ratios of atomizing reduction steel slag, but flexural strengths of the specimens showed a maximum strength at the 50% of replacement ratios of atomizing reduction steel slag. It was concluded that addition ratio of polymer binder, which affect greatly on the prime cost of production of polymer concrete, could be reduced by maximum 18.2 vol% because the workability of the polymer concrete was remarkably improved by using the atomizing reduction steel slag. However, further study is required because the mechanical strength of the specimen using atomizing reduction steel slag was greatly reduced in hot water resistance test.

• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.99-103
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• 2009

This research is the result of investigating engineering characteristics of slime generated during construction of deep mixing method. Mechanical characteristics of slime have been studied through literature review and laboratory tests of unconfined compression test, permeability test and settling tests were performed. As result of field observation of slime being generated, slime started to be produced right after flight auger was penetrated into a ground and its amount was increased in progress. Unconfined compressive strength of specimen with slime obtained from in field was measured in the range of $929.7{\sim}3,509.8kN/m^2$ and the value of unconfined compressive strength was found to be changed significantly with mixing ratio of soil, cement and binder. Permeability of them was measured in the range of $4.53{\times}10^{-7}{\sim}6.62{\times}10^{-6}cm/sec$ so that the mixture was appropriate as a impervious barrier. It was also know that the value of permeability was changed with the mixing ratio of binder. As test results of solidifying slime specimen prepared in the laboratory, good quality of cement mixture with coarse soil of sand were produced, compared with fine soils of silt and clay.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.36-43
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• 2010

Changes in runoff and soil erosion at slightly hilly erosive plots with pear trees over a three-year period were monitored under two distinct types of weed treatment by herbides : (1) pre-emergence herbicide with glyphosate; (2) post-emergence herbicide with paraquat. The numbers of rainfall events from June to Nov for three years of experimental periods were approximately 50 times in the plots having 5.5%to 10.2%slope at an altitude of 125 m. The steady-state infiltration rate was generally increased in the bare plot from which all weeds were removed while it was decreased in the herbicide treated plots and control. The runoffs from the control plot during the experimental periods were always less than those from plots of the herbicide-treated and the bare. The runoff under the same rainfall intensity was decreased in the order of bare, glyphosate, paraquat, and control. This results indicated that the removal time of weed by the different types of herbicides might influenced the runoff rate. For the first two years of the experimental periods, loss of fine fraction was much greater than that of coarse fraction while soil loss was correlated neither with total rainfall nor amount of runoff. The soil erosion rate under the same rainfall intensity was increased in the order of control, glyphosate, paraquat, and bare plot. However, there were not much differences in the soil loss for all plots under a relatively lower rainfall intensity less than 30 mm $day^{-1}$, resulting in rainfall intensity was important factor on soil erosion.

• Resources Recycling
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• v.31 no.6
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• pp.81-91
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• 2022

The use of lithium-ion batteries increases significantly with the rapid spread of electronic devices and electric vehicle and thereby an increase in the amount of waste batteries is expected in the near future. Therefore, studies are continuously being conducted to recover various resources of cathode active material (Ni, Co, Mn, Li) from waste battery. In order to recover the cathode active material, black mass is generally recovered from waste battery. The general process of recovering black mass is a waste battery collection - discharge - dismantling - crushing - classification process. This study focus on the crushing/classification process among the processes. Specifically, the particle size distribution of various samples at each crushing/classification step were evaluated, and the particle shape of each particle fraction was analyzed with a microscope and SEM (Scanning Electron Microscopy)-EDS(Energy Dispersive Spectrometer). As a result, among the black mass particle, fine particle less than 74 ㎛ was the mixture of cathode and anode active material which are properly liberated from the current metals. However, coarse particle larger than 100 ㎛ was present in a form in which the current metal and active material were combined. In addition, this study developed a PBM(Population Balance Model) system that can simulate two-species mixture sample with two different crushing properties. Using developed model, the breakage parameters of two species was derived and predictive performance of breakage distribution was verified.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5C
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• pp.209-218
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• 2010

In residual soils, large particles such as rock fragments or gravel are surrounded by sand or clay. The strength of such granular mixtures can be controlled by the concentration of fine or coarse grains. The percentage by weight, size or shape of gravel in the mixture that can control the strength of the mixture has not been clearly determined for various granular mixtures. In this study, the effect of dispersed gravels on the shear characteristics of sand was evaluated. Large and small gravels were inserted in the middle of each layer with moist Nakdong River sand and compacted into a cylindrical sample with five equal layers. Embedded gravel ratios by weight were 0, 3, 9, and 14%. After consolidation, a series of undrained triaxial compression tests was performed on Nakdong River sand with dispersed gravels. Maximum deviator stresses of the Nakdong River sand with large gravels decrease up to 38% as a percentage of embedded gravels increases. Such strength degradation decreases as a confining pressure increases. The maximum deviator stress increases as the percentage by weight of small gravel increases; at 3 or 9% of gravel weight it slightly increases but at 14% of gravel weight it increases up to 34%.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.3
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• pp.279-284
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• 1999

Fly ash is the fine ash particles that are flying out of chimney of the thermoelectric power plant where coals are used as fuel. There are two kinds of fly ashes from anthracite and bituminous coal. By scanning electron microscope(SEM) morphological feature of fly ash was confirmed to the exact spherical particles with the diameter variation from the fine to the largest about $50{\mu}m$(mainly silty particle). Surface of anthracite ash particle was very smooth but that of bituminous was somewhat coarse. To find the utilization of fly ash for improving soil permeability, soils of 4 kinds of different texture, clay, clay loam, sandy clay loam and sand mere applied with 7 levels of fly ash: 0, 10, 20, 40, 60, 80, 100%(w/w) and their saturated hydraulic conductivity(Ks) were determined at each application by constant head method. In clay soil with low water permeability, Ks value was increased about 10 times from $10^{-8}$ to $10^{-7}m\;s^{-1}$ level with application of 10% fly ash and it was slightly increased with increasing fly ash application from 40 to 80%. In clay loam Ks value was about $10^{-7}m\;s^{-1}$ level and its value was not influenced by the fly ash application. In sandy clay loam with relatively high permeability, Ks value was decreased about 10 times from $10^{-5}$ to $10^{-6}m\;s^{-1}$ level with application of 10% fly ash and also decreased about 50 times from $10^{-5}$ to $5.0{\times}10^{-7}m\;s^{-1}$ with application of more than 20% fly ash. In sand with very high permeability, Ks value was decreased about 10 times from $10^{-4}$ to $10^{-5}m\;s^{-1}$ level with application of 10% fly ash and also decreased about 100 times from $10^{-4}$ to $10^{-6}m\;s^{-1}$ level with application of 20% fly ash and continuously decreased about 500 times from $10^{-4}$ to $5.0{\times}10^{-7}m\;s^{-1}$ level with application of more than 40% fly ash. In conclusion by fly ash application saturated hydraulic conductivity was increased in clay soil, on the contrary it was decreased in sandy soils. Fly ash may be used as a material for amelioration of soil permeability.

• Korean Journal of Soil Science and Fertilizer
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• v.1 no.1
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• pp.129-136
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• 1968

Low-Humic Gley Soils occur very commonly in Korea and constitute important paddy soils of the country. These soils are developed either on alluvial or fluvio-marine materials. The soils in the present invest igation are derived from the latter. The interesting morphological features of these two soils are the presence of $FeCO_3$ concretions in the subsoil and the occurrence of a buried black organic horizon of variable thickness(25-100 cm). The organic horizon overlies the greenish marine material and underlies the continental material. These soils have poor drainage and are wet most of the year. The presence of $FeCO_3$ concretions in poorly drained paddy soils has previously been reported in North America(8), Japan(9) and West Europe(7). The purpose of this investigation is to study the chemical and mineralogical characteristics of these soils; and the genesis of $FeCO_3$ concretions. Profile samples of both these soils were collected from Gimjae area, in co-operation with the Soil Survey Party. These profiles were described as follows:

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.225-236
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• 2003

In order to understand the relationship of depositional environment between fluvial and estuarine-embayment in Han River system, including depositional change in main Han River, more than 250 bottom sediment and 70 suspended sediment were analyzed with hydrologic data. Based on the previous data, the study area can be divided into two environment(fluvial and estuarine-embayment) by Singok underwater dam. The gravelly facies occurs in the South and North Han Rivers and sandy and silty facies occupies in the main Han River. Depositional environment of main Han River changed mainly because of limited sediment transport and hydrological condition. In the estuarine-embayment environment, coarse-grained sediments are dominant in tidal channel and of shore whereas fine and poorly sorted sediments are observed in coastal area. During moderate period, relationship between fluvial-estuarine-embayment system is discontinuou s because of flow restriction by artificial construction such as dam and underwater dam, so that each river system characterizes the individual environment. Fluvial and estuarine system is influenced by tide and, thus, transition zone of estuarine- embayment system moves landward. During flooding period, however, each river system is integrated as continuous depositional system by high discharge and, thus, transition zone of fluvial-estuarine-embayment system moves seaward. For further detailed systems about the lower Singok under-water dam, joint research of South-North Korea should be necessary.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.2
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• pp.145-156
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• 2003

The atmospheric aerosols collected at the 1100 site located in Mt. Halla have been analyzed to investigate their compositions and chemical characteristics . The average concentrations of water-soluble cations were in the order of N $H_{4}$$^{+}$ > $Ca^{2+}$ > N $a^{+}$ > $K^{+}$ > $Mg^{2+}$ during the spring, showing high increase of $Ca^{2+}$ concentration with the value of 0.60 $\mu\textrm{g}$/ $m^3$, and N $H_{4}$$^{+}$> N $a^{+}$> $K^{+}$> $Ca^{2+}$ > $Mg^{2+}$ during the other seasons. The average concentrations of anions have shown in the order of S $O_{4}$$^{2-}$ > N $O_{3}$$^{[-10]}$ >C $l^{[-10]}$ for all seasons, and S $O_{4}$$^{2-}$ and N $O_{3}$$^{[-10]}$ had higher concentrations in spring with the values of 4.84 $\mu\textrm{g}$/ $m^3$ and 1.08 $\mu\textrm{g}$/ $m^3$, respectively. From the analytical data of size-segregated particles by cascade impactor sampling, the components of N $H_{4}$$^{+}$, S $O_{4}$$^{2-}$, N $O_{3}$$^{[-10]}$ and $K^{+}$ were distributed mainly in fine particles, but $Ca^{2+}$, N $a^{+}$, $Mg^{2+}$ and C $l^{[-10]}$ were included mostly in coarse particles. The correlation coefficients of nss-S $O_{4}$$^{2-}$/N $H_{4}$$^{+}$, nss-S $O_{4}$$^{2-}$/ $K^{+}$ and N $O_{3}$$^{[-10]}$ /nss-C $a^{2+}$ showed quite high values with 0.871, 0.857 and 0.654, respectively Based on the study of enrichment factors, it is considered that N $a^{+}$, $Mg^{2+}$, C $l^{[-10]}$ and $Ca^{2+}$ components were delivered from oceanic and soil sources, but S $O_{4}$$^{2-}$, N $O_{3}$$^{[-10]}$ and N $H_{4}$$^{+}$ might have other source origins. The factor analysis study showed the aerosol at the 1100 site was influenced mainly by anthropogenic factors, followed by oceanic and soil factors. followed by oceanic and soil factors.