• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.43-47
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• 2012

A evaluation for the strength of rock includes a lot of uncertainty due to existence of discontinuity surface and weakness plain in the rock mass, so essential test results and other data for the resonable strength analysis are absolutely insufficient. Therefore, a analytical technique to reduce such uncertainty can be required. A probabilistic analysis technique has mainly to make up for the uncertainty to investigate the strength of rock mass. Recently, a artificial neural networks, as a more newly analysis method to solve several problems in the existing analysis methodology, trends to apply to study on the rock strength. In this study the unconfined compressive strength from basic physical property values of sedimentary rock, black shale and red shale, distributed in Daegu metropolitan area is estimated, using the artificial neural networks. And the applicability of the analysis method is investigated. From the results, it is confirmed that the unconfined compressive strength of the sedimentary rock can be easily and efficiently predicted by the analysis technique with the artificial neural networks.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.3
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• pp.175-182
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• 2022

Translocation of azurophil granules is pivotal for bactericidal activity of neutrophils, the first-line defense cells against pathogens. Previously, we reported that lysophosphatidylcholine (LPC), an endogenous lipid, enhances bactericidal activity of human neutrophils via increasing translocation of azurophil granules. However, the precise mechanism of LPC-induced azurophil granule translocation was not fully understood. Treatment of neutrophil with LPC significantly increased CD63 (an azurophil granule marker) surface expression. Interestingly, cytochalasin B, an inhibitor of action polymerization, blocked LPC-induced CD63 surface expression. LPC increased F-actin polymerization. LPC-induced CD63 surface expression was inhibited by both a Rho specific inhibitor, Tat-C3 exoenzyme, and a Rho kinase (ROCK) inhibitor, Y27632 which also inhibited LPC-induced F-actin polymerization. LPC induced Rho-GTP activation. NSC23766, a Rac inhibitor, however, did not affect LPC-induced CD63 surface expression. Theses results suggest a novel regulatory mechanism for azurophil granule translocation where LPC induces translocation of azurophil granules via Rho/ROCK/F-actin polymerization pathway.

• Tunnel and Underground Space
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• v.18 no.1
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• pp.80-89
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• 2008

The influence of in-situ rock stress on the stability of an underground rock structure increases as the construction depth become deeper and the scale of a rock structure become larger. In general, hydraulic fracturing stress measurement has been performed in the surface boreholes of the target area at the design stage of an underground structure. However, for some areas where the high horizontal stresses were observed or where the overstressed conditions caused by topographical and geological factors are expected, it is desirable to conduct additional in-situ stress measurement in the underground construction site to obtain more detailed stress information for ensuring the stability of a rock structure and the propriety of current design. The study area was a construction site for the additional underground oil storage facility located in the south-east part of OO city, Jeollanam-do. Previous detailed site investigation prior to the design of underground structures revealed that the excessive horizontal stress field with the horizontal stress ratio(K) greater than 3.0 was observed in the construction area. In this study, a total of 13 hydraulic fracturing stress measurements was conducted in two boreholes drill from the two water tunnel sites in the study area. The investigation zone was from 180 m to 300 m in depth from the surface and all of the fracture tracing works were carried out by acoustic televiewer scanning. For some testing intervals at more than 200 m ind depth from surface, the high horizontal stress components the horizontal stress ratio(K) greater than 2.50 were observed. And the overall investigation results showed a good agreement with the previously performed test.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.spc
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• pp.40-44
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• 2009

This study was carried for the understanding of infiltration and percolation characteristics of water in agricultural land filled with rock-dust (Technosols). The experiment was performed at two sites (A, B), and soil horizons of the sites were classified with 4 layers, respectively. The soil texture of all soil horizons was analyzed with silt loam (SiL) except for the soil texture, which was loamy sand (LS), at the lowest horizon of measurement site A. The bulk densities at each horizon of two soils were mostly over $1.49g{\cdot}cm^{-3}$, which is very higher than $1.25g{\cdot}cm^{-3}$ of typical medium-textured mineral soil, except for the surface of site A measured immediately after tillage. The concentrations of $P_2O_5$ at surface of two soils s were 1962 (A), 1613 (B) $mg{\cdot}kg^{-1}$, respectively. These concentrations are 3.2~6.5 times of $300{\sim}500mg{\cdot}kg^{-1}$, which is the optimum concentration for crop growth. Infiltration rates at surface of the soils were 3.54 (A), 2.85 (B) cm $hr^{-1}$, but percolation rates at soil horizons under the surface were below 0.3 (A), below 0.003 (B) cm $hr^{-1}$. These results would be because the surface soils were managed by tillage and crop planting etc., but soils under surface were formed with structural problems occurred at the formation time of agricultural land accumulated with rock-dust or a compaction by farm machines.

• Geomechanics and Engineering
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• v.34 no.2
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• pp.139-154
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• 2023

Red-bed soft rock is a common stratum and it is necessary to evaluate the mechanical properties and bearing capacity of red-bed soft rock mass affected by different environmental effects. This paper presents a complete procedure for evaluating the bearing capacity of red-bed soft rock by means of geophysical exploration and in-situ rock mechanics tests. Firstly, the thickness of surface loosened rock mass of red-bed soft rock was determined using geophysical prospecting method. Then, three environmental effects, including natural weathering effect, dry-wet cycling effect and concrete sealing effect, were considered. After each effect lasted for three months, in-situ rock mass mechanical tests were conducted. The test results show that the mechanical properties of rock mass considering the sealing effect of concrete were maintained. After considering the natural weathering effect, the mechanical parameters decrease to a certain extent. After considering the effect of dry-wet cycling, the decreases of mechanical parameters are the most significant. The test results confirm that the red-bed soft rock dam foundation rock mass will be significantly affected by various environmental effects. Therefore, combined with the mechanical test results, some useful implementations are proposed for the construction of a red-bed soft rock dam foundation.

• Tunnel and Underground Space
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• v.16 no.2 s.61
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• pp.189-193
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• 2006

Guide line for rock blasting design of the MOCT(Ministry of Construction and Transportation) adopts attenuation equation of du Pont company for blasting vibration. In this paper the validity of the equation is studied by comparing with several equations of Dowding, Devine and author's induced from the domestic vibration data. The equation is inadequately used and predicted values are proved to be underestimated and causes vibration problems.

• Geomechanics and Engineering
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• v.11 no.6
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• pp.867-877
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• 2016

Collapse shape of tunnel roof in layered Hoek-Brown rock media is investigated within the framework of upper bound theorem. The traditional collapse mechanism for homogeneous stratum is no longer suitable for the present analysis of roof stability, and it would be necessary to propose a curve failure mode to describe the velocity discontinuity surface in layered media. What is discussed in the paper is that the failure mechanism of tunnel roofs, consisting of two different functions, is proposed for layered rock media. Then it is employed to investigate the impending roof failure. Based on the nonlinear Hoek-Brown failure criterion, the collapse volume of roof blocks are derived with the upper bound theorem and variational principle. Numerical calculations and parametric analysis are carried out to illustrate the effects of different parameters on the shape of failure mechanism, which is of overriding significance to the stability analysis of tunnel roof in layered rock media.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.359-364
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• 2003

For safety evaluation of a rock-fill dim, it is often necessary to investigate spatial distribution of weak zones such as fracture. Both DC-resistivity survey and seismic(SASW) method are usually used for the purpose. Recently, Multichannel analysis of surface waves(MASW) method which makes up for the weak point of SASW method is developed and the site examination which is simple came to be possible comparatively. In order to obtain 2-D shear-wave velocity(Vs) profile along the dam axis that can be associated with dynamic properties of filled materials, MASW method was adapted. Then, DC-resistivity survey and drilling survey were performed to compare with each results. We confirmed that the MASW method and DC-resistivity survey show complementary result that corresspond with drilling result. Therefore, MASW method is an efficient method for dynamic characterization of dam-filling materials and also the combination of related methods such as DC-resistivity can lead to an effective safety evaluation of rock-fill dam.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.2
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• pp.78-85
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• 2009

High performance functional fibers are demanded increasingly in the modern industries, while the inorganic fibers such as carbon fibers, glass fibers, and metal fibers are representative among them in that they have high strength, consistent properties in a broad temperature change, etc.. This paper reports on the experimental trial to apply the microwave furnace on melting the natural basalt rock that spreads overall on the global surface and is supposed to be used as the raw material for the inorganic high performance fiber. Results showed that the new method to use the microwave as the heating source to melt the basalt rock was feasible. The crucible spinning could effectively applied for producing the basalt fibers up to 10 micrometer diameter, when the crushed basalt rocks were used. For drawing the molten basalt the drawing roller surface feature was a very important factor.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.610-614
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• 2005

Rock mass classification by using electrical resistivity tomography(ERT) method is widely performed for the determination of rock support type in tunnel design. In the region of high electrical noise level, however, the result of the ERT will have many erroneous features. In this study, the back ground electrical noise had been measured to find out the reason why the results of ERT in this area did not agree to the expected geology confirmed by boreholes. In order to overcome this limitation of ERT, a hybrid surface-borehole array seismic refraction tomography had been followed. Using this technique, we could get P-wave velocity section including the depth level of tunnel. The comparison of the P-wave velocity and RMR shows fairly good statistical relationship to make it possible to set up the rock mass classification for the entire tunnel line.