• Tunnel and Underground Space
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• v.22 no.6
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• pp.429-437
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• 2012

This study predicted temperature in the disposal tunnels using computational fluid dynamics based on natural ventilation quantity that comes from high altitude and temperature differences that are the characteristics of high level waste repository. The result of the previous study that evaluated quantitatively natural ventilation quantity using a hydrostatic method and CFD shows that significant natural ventilation quantity is generated. From the result, this study performed the prediction of temperature in disposal tunnels by natural ventilation quantity by the caloric values of the wastes, at both deep geological repository and surface repository. The result of analysis shows that deep geological repository is effective for thermal control in the disposal tunnels due to heat transfer to rock and the generation of sufficient natural ventilation quantity, while surface repository was detrimental to thermal control, because surface repository was strongly affected by external temperature, and could not generate sufficient natural ventilation quantity. Moreover, this study found that in the case of deep geological repository with a depth of 200 m, the heatof about $10^{\circ}C$ was transferred to the depth of 500 m. Thus, it is considered that if the high level waste repository scheduled to be built in the country is designed placing an emphasis on thermal control, deep geological repository rather than surface repository is more appropriate.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.06a
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• pp.125-146
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• 1998

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.255-262
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• 1999

This paper summarizes the results of a study which uses the recently developed Optical Profile Microscopy technique (Dove and Frost, 1996) as the basis for investigating the role of geomembrane surface roughness on the shear strength of goomembrane/geotextile interfaces. The results show that interface friction can be quantitatively related to the surface roughness of the geomembrane. The peak and residual interface strengths increase dramatically through the use of textured geomembranes as opposed to smooth geomembranes. For the smooth geomembranes, the sliding of the geotextile is the main shear mechanism. For the textured geomembranes, the peak interface strength is mainly mobilized through the micro-texture of the geomembrane, however, the residual interface strength is primarily attributed to macro scale surface roughness which pulls out and breaks the filaments from the geotextile. The results of this study can be extended to the other interfaces such as joints in rock mass, and also can be used to provide a quantitative framework that can lead to a significantly improved basis for the selection and design of geotextiles and geomembranes in direct contact.

• Carbon letters
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• v.1 no.3_4
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• pp.138-142
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• 2001

The effect of electrochemical surface treatments in KOH chemical solution on microstructures of carbon blacks was investigated in terms of surface functional values and XRD measurements. And their mechanical interfacial properties of the carbon blacks/rubber composites were studied by the composite tearing energy ($G_{IIIC}$). It was found that the development of basic-surface functional groups lead to the significant physical changes of carbon blacks, such as, decrease of the interlayer spacing ($d_{002}$), increase of the crystalline size along c-axis ($L_c$), and increase of degree of crystalline (${\chi}_c$). This treatment is possibly suitable for carbon blacks to be incorporated in a hydrocarbon rubber matrix, resulting in improving the hardness and tearing energy of the resulting composites.

• Carbon letters
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• v.1 no.1
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• pp.1-5
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• 2000

The effect of surface free energy on the positive temperature coefficient (PTC) of carbon black/thermoplastic resin composites was investigated. The thermoplastic resins such as EVA, LDPE, LLDPE and HDPE were used with the addition of 30 wt.% of the carbon black. The surface free energy of the composites was studied in the context of two-liquid contact angle measurements, i.e., deionized water and diiodomethane. It was observed that the resistivity on PTC composites Was greatly increased near the crystalline melting temperature, due to the thermal expansion of polymeric matrix. From the experimental results, it was proposed that the decrease of surface free energy induced by interactions between carbon black surfaces and polymer chains is an important factor to the fabrication of a PTC composite made of carbon black and polymeric matrix.

• Journal of Conservation Science
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• v.28 no.1
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• pp.39-52
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• 2012

The Usuki Stone Buddha Statues in Oita are consisted of 60 Buddhas which represent of Japan carved on the rock-cliff in the 12 to 14th centuries. The basement rock of the statues is dark gray welded lapilli tuff that containing the Aso-4 pyroclastic rock group. Deterioration maps for the Hoki I and the Furuzono Buddha Statues group show multi-directional fissures on the Cakra, and sheeting-off zone at the margin of uprising water. Deterioration rate of the Hoki I group was calculated fissure about 121 in number, 19% of sheeting-off zone and 51% of biological weathering in surface of area. And the Furuzono group was also evaluated as about 48 of fissures in number, 24% of sheeting-off zone and 41% biological weathering. The slope stability assessment results, the Hoki I developed discontinuous planes has possibility of planar, toppling and wedge failures in all caves. Ultrasonic velocity of the Aizen-myooh (basement rock) ranges from 1,520 to 2,794 (average 2,298m/s). And pedestal of Amita-yeorae which has been replaced by new fresh rock is measured as 3,242 to 4,141 (average 3,813m/s). Therefore, we establish of planing conservation treatment and reinforcement methods to fissure, cavity, sheeting-off zone in the Buddha surface.

• Journal of Conservation Science
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• v.6 no.1 s.7
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• pp.31-60
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• 1997

Stone-cultural-properties, distributed in Naju, Hwasun and a part of Jangheung, have been investigated and studied on the characteristics, rock weathering and phases in the geological and conservational points of view. The properities involve pagoda and twelve stupas, four stone-buddha, three stone monuments, two stone-lantern, four stone-Jangseung, one and flag-pole. The rocks used are mainly pebble-bearing tuffaceous rocks of the Cretaceous age which are widely distributed in the area. However, granites are also used in some properties. These rocks are strongly influenced by weathering and pervasive moss. The mottled rock surfaces in some properties are in colors due to pervasive moss different. Parts of some cultural properties are broken which results in structurally unstable. Cultural properties in the area are relatively well conserved at the earth consolidated by ramming and by iron fence. However some cultural properties are partly repaired by using other hinds of rock phases which results in different colors in weathered rock surface. For conservation, rock phases, weathered surface colors, and relationships with original parts must be scientifically considered in repairment forward.

• Journal of fish pathology
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• v.23 no.3
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• pp.281-291
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• 2010

Crytocaryon irritans infection of rock bream was investigated in embankment fish farm from July to December 2009. Prevalence variation was 20.0~88.0% that was high in september and was low in July. While no mortality was found in July and August, it occurred after mid september. Environmental conditions during the survey period were water temperature $19.3{\sim}24.3^{\circ}C$, dissolved oxygen $5.0{\sim}7.1\;mg\;L^{-1}$ and salinity 31.9~33.7 psu, and the water temperature during mortality season was $24.0^{\circ}C$. External symptom of the rock bream was secretion mucus but swimming showed fine in the early infected period. While, the symptoms in the severe outbreak season were excess of mucus, falling off tail and congestion, bleeding spot the surface and weakened swimming. We observed free living and parasitic stages in the gills and body surface of rock bream. Hepato somatic index (HSI) was $1.9{\pm}1.1{\sim}3.5{\pm}1.7%$, which was low in the September being mortality season but was high in November. The percentages of hematocrit infected with Crytocaryon irritans were 37.3% and 41.0% in July and August, respectively while they gradually decreased to 32.1% and 24.2% in september and October, respectively. Total cholesterol and Triglyceride values rapidly decreased by October. After mortality, AST and ALT were 7 and 5 folds higher compared to non-mortality season.

• Journal of The Geomorphological Association of Korea
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• v.19 no.3
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• pp.51-69
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• 2012

Physical strength of the rock is the most important factor of resistance to erosion and has been measured through various way. Bedrock microforms, like potholes and grooves, are the forms sculpted by the erosional processes of flow and the location and morphology are strongly affected by the differential erosion. It also assumed that the physical strength of the rock controls the erosion rate and mode of erosion. The schmidt hammer has been used to measure the rock strength in the field for the geomorphological research. To find the relationship between the rock strength and microforms, Schmidt hammer's R(rebound) were measured in the Baeksuktan, middle reach of Gilancheon, Cheongsong, Gyungsangbuk do. The overall values of rebound of the local sandstone showed over 65 in most cases, so it can be regarded as 'very strong'. It is found that the rebound values of the rock surface decreased towards current water level. It also, however, found that there was no systematic differences in rebound values among the topographically high and lows in the bedrock surface. There was no statistically significant difference in rebound values of the area with well developed microforms and others. The values of R from the exposed faces and inside of the microforms are similar. In the case of conglomerate, the part with the gravel showed higher values that the parts with sands. The rebound values are decreased near of(<1cm) the geological discontinuities(including joint and faults), so this line of weakness could be the point of initiation of active erosion to form microforms. However there is large variations in rebound values within this part. It also should be mentioned that topological relation between the strike of the geologic discontinuities and flow direction looks control the mode of erosional processes.

• Journal of the Korean earth science society
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• v.35 no.7
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• pp.501-517
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• 2014

Based on a summary of the previous studies on columnar joints, this study presents research strategies and subjects to understand a formation of columnar joints, and its application in South Korea as follows; geometry of colonnade and entablature, formation mechanism and pattern change, surface morphology and internal structure, platy joint at the top and the bottom of columnar joints, crack patterns in drying starch-water slurries, using numerical models and computer graphics on joint formation, scale and geometry concerned with occurrence of volcanic rock, petrological and mineralogical study of the host rock. Additionally, more research is needed, such as deformation of column pattern during the hot state, secondary landform by alteration and weathering on the Earth's surface such as rock stream, tor and tafoni. This study will take an active role in research of columnar joint and the Cenozoic lava flow of South Korea. Results of this study will be useful to the activation of geotourism and geological field study.