• 한국해양학회지
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• v.18 no.1
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• pp.21-28
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• 1983

A series of experiments was performed to increase and make our puantitive understanding of the entrainuent and settling processes of fine-grained sediments, which are of critical importance to construct a predictive model of sediment experiments were performed in an annular flume. A rotating top produced a turbulent flow which in turn exerted and are shown to be dependent on the sediment concentration and the presence of clay minerals. The parameters on which entrainment strongly depends were identified to be the shear stress, water content (time ofter deposition), and the type of sediment (grain size and mineralogy).

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.140-145
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• 2010

Consolidation in cohesive soils mainly focuses on compressibility of soils, but it affects solute transport in some cases. The consolidation process takes on particular significance for fine grained soils at high water content, such as dredged sediments, but has also been shown to be important for compacted clay liners during waste filling operation. Numerical investigation using CST1 and CST2 was reviewed on consolidation-induced solute transport in this paper, especially with the development of CST2 model, verification by comparing experimental results with numerical simulations, and cases studies regarding transport in a confined disposal facility (CDF) and during in-situ capping. The importance of the consolidation process on solute transport is accessed based on simulated concentration or mass breakthrough curves. Results indicate that neglecting transient consolidation effects may lead to significant errors in transport analyses, especially with soft contaminated cohesive soils undergoing large volume change.

• Journal of the Korean Ceramic Society
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• v.31 no.4
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• pp.399-406
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• 1994

The SiC/MoSi2 composite material was prepared by infiltration with the mixture of metal Si and MoSi2 into the preform of $\alpha$-SiC and graphite under the vacuum atmosphere of 10-1 torr. The mechanical properties, phases and microstructural characteristics have been investigated by employing an universal testing machine, scanning electron microscope and X-ray diffractometer. With the increase of MoSi2/Si mixing content, the quantity of the residual silicon phase was decreased and the hardness and fracture toughness of composite materials were increased. Also, as the infiltration temperature increased, a lot of fine-grained $\beta$-SiC phases, which were produced from the reaction of graphite and liquid silicon melt, were transformed to $\alpha$-SiC phases.

• Economic and Environmental Geology
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• v.10 no.3
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• pp.99-105
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• 1977

Mineralogical study of original and crushed zinc ores as well as mill products was made in order to find out the cause of low-grade concentrate and the scheme of raising its grade. Low-grade concentrate is due to 1) the abundance of other independent sulfides (arsenopyrite, pyrrhotite, chalcopyrite, stannite) and silicate (quartz) in the zinc concentrate, 2) the presence of composite grains of sphalerite and other sulfides or silicate, 3) the presence of a lot of very fine-grained particle of stannite and chalcopyrite within the sphalerite grains, and 4) the high content of iron in sphalerite. It is proposed that further crushing and other appropriate processing should be made in order to increase the grade of zinc concentrate.

• Journal of Environmental Science International
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• v.16 no.5
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• pp.657-664
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• 2007

The content and distribution of some heavy metals (Fe, Mn, Cr, Co, Cu, Ni, Zn and Pb) were investigated in the <$63{\mu}m$ bed sediments of the Mangyeong river to recognize the extent of contamination. Results showed that a wide range of concentrations was apparent for every metal. These variations were particularly significant at the confluence of tributaries. High levels of metals occur mainly in the confluence of tributaries. Geoaccumulation indexes have been calculated to assess whether the concentration observed represent background or contaminated levels. It is proved that the Mangyeong River is moderately to strongly polluted for Mn, Cr, Cu, Zn and Pb. The spatial extent of pollution was examined, and it was found that the most polluted area is located in the confluence of Iksan and Jeonju tributaries.

• The Journal of the Petrological Society of Korea
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• v.15 no.3 s.45
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• pp.139-153
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• 2006

For the characteristics of rock material and standardization, flagstones of the trifurcated path in Jongmyo Royal Shrine, registered as World Cultural Heritage, were studied on the basis of petrographic, petrochemical and magnetic properties. The flagstones are composed mainly of pale gray fine to medium grained hornblende biotite granite, pale gray fine to medium grained biotite granite, pale pink medium to coarse grained biotite granite, pink medium to coarse grained biotite granite and minor pegmatite and schist. Flagstone represents the average size of $65cm{\times}4cm$ (standard deviation $12cm{\times}7cm$) and suitable (34.7%), common (41.4%) and unsuitable (23%) in roughness. It is interpreted that pale pink and pink granite, pegmatite, schist and other flagstones with unsuitable state are not original rock materials and were exchanged during restoration, in the past. The number of these non-original rock materials is about 560 flagstones. We suggests that the standard flagstone of the trifurcated path is pale gray fine to medium grained biotite granite (${\pm}$hornblende in trace), 70wt.% in $SiO_2$, content, and ${\pm}0.1{\times}10^{-3}\;SI$ in magnetic susceptibility.

• Journal of the Korean Geosynthetics Society
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• v.14 no.1
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• pp.59-65
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• 2015

The objective of the study is to verify a new calibration equation of dry density and water contents with TDR. Since the traditional calibration equation was proposed, some research to develop a new calibration equation has been conducted by several researchers. As traditional calibration equation is difficult to be applied for loose soil and fine-grained soil at high water contents, this study developed a new calibration equation. Thus, this study introduces a new calibration equation and its applicability by comparing TDR test results with conventional test results. Based on the analyses, the calibration equation for water content has large error. A new calibration equation was proposed and it showed more than 95% accuracy for estimating water content of soil.

• Geomechanics and Engineering
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• v.23 no.4
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• pp.301-311
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• 2020

In this study, shear strength behavior of fine-grained soils was investigated under unsaturated conditions. The samples in the unsaturated state were subjected to a net normal stress (σ-u_a) of 40 kPa and different matric suctions (u_a-u_w) of 50, 100 and 150 kPa. The matric suction values applied in the triaxial tests were selected according to the bubbling pressures determined from the SWC curves. The study was carried out on prepared re-constituted cylindrical samples by uniaxial consolidation of soil slurries. First, consolidated drained (CD) triaxial compression tests were performed on the saturated samples and the cohesion and angle of internal friction were determined. After that, drained triaxial compression tests under matric suctions were performed on the unsaturated samples. In order to obtain unsaturated test results, cohesion and internal friction angle values of saturated samples were used. The nonlinear surface representing the shear strength surface was approximated consisting of two planes (double planar surface). The reason for the nonlinear behavior of some soils is that the amount of sand content contained in it is relatively high and the bubbling pressure/permanent water content value is relatively low.

• Journal of Internet Computing and Services
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• v.19 no.1
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• pp.155-166
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• 2018

These days, online media, such as blogospheres, online communities, and social networking sites, provides the uncountable user-generated content (UGC) to discover market intelligence and business insight with. The business has been interested in consumers, and constantly requires the approach to identify consumers' opinions and competitive advantage in the competing market. Analyzing consumers' opinion about oneself and rivals can help decision makers to gain in-depth and fine-grained understanding on the human and social behavioral dynamics underlying the competition. In order to accomplish the comparison study for rival products and companies, we attempted to do competitive analysis using text mining with online UGC for two popular and competing ramens, a market leader and a market follower, in the Korean instant noodle market. Furthermore, to overcome the lack of the Korean sentiment lexicon, we developed the domain specific sentiment dictionary of Korean texts. We gathered 19,386 pieces of blogs and forum messages, developed the Korean sentiment dictionary, and defined the taxonomy for categorization. In the context of our study, we employed sentiment analysis to present consumers' opinion and statistical analysis to demonstrate the differences between the competitors. Our results show that the sentiment portrayed by the text mining clearly differentiate the two rival noodles and convincingly confirm that one is a market leader and the other is a follower. In this regard, we expect this comparison can help business decision makers to understand rich in-depth competitive intelligence hidden in the social media.

• 한국해양학회지
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• v.24 no.3
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• pp.132-147
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• 1989

A total of 83 surface sediments and 55 sea water samples, collected from the southwestern sea of Cheju Island, were analyzed in order to understand their textural characteristics, geochemical composition and the clay mineralogical features. The sediments were subdivided into ten textural classes, namely clayey sand, slightly gravelly muddy sand, sandy clay, clay and mud. The coarse and fine-grained mixed sediments are distributed in the northern part and around the Island, whereas the fine-grained deposits are mainly distributed in the central and southern parts of the study area; small scale mud patches are distributed in the southwestern and northern parts of Cheju Island. The high concentration of total suspended matter in study area gradually increase toward the southwestern and northwestern offshore area. The concentration of geochemical elements is as follow: the content of Mn, Al, Zn, Cr, Cu and Sn increase toward the southern part which is covered mainly with fine-grained deoposits, whereas the content of Ca, Mg and Ag is higher in the northern area; the elements such as Ni, Na, Fe and Pb are more concentrated relatively in muddy deposits rather than in sandy sediments. The light minerals such as Na-Ca feldspars show a high content around the Socotra Rock, toward the Soheugsan and Cheju Islands, but the K-feldspars are relatively high around the Cheju Island. It was noticed that the provenance of these sediments is partly influenced by the geological characteristics near the island. X-ray diffractogram for clay minerals from the southeastern mud patch and around the Soheugsan Island shows the diagnostic calcite peak indicating that the greater part of these clay fraction may have been derived from present and ancient Hwangho River. The high concentration of smectite in the northern part near the Cheju and around the Soheugsan Islands, eastern side of Socotra Rock probably result from supplies smectite altered from volcanic materials distributed in the Cheju Island and Socotra Rock, whereas the samples near the Chuja and northern parts of the Cheju Island contain weak calcite peak and high concentration of kaolinite and chlorite which is closely related to the geolgical characteristics on the adjacenting land area.