• Tunnel and Underground Space
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• v.10 no.3
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• pp.395-402
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• 2000

The influence of the mined-out caves on the stability of the high speed railway tunnel was investigated with a series of geological logging and in-situ tests on the one hand, and with the rock mass classification using the multiple regression analysis on the other hand. The rock mass in this area can be classified as 'fair', and the condition of the discontinuities plays the most important role in the classification of the rock mass. The results of the analysis obtained by the FLAC showed that the western part of the tunnel locating at 50m above the mine cavities could be affected by subsidence associated with a considerable deformation, the magnitude of which might depend on the properties of the rock mass.

• Tunnel and Underground Space
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• v.10 no.3
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• pp.309-315
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• 2000

For proper sampling of a rock and preparation of specimens, the representative elementary volume (REV) should be determined in rock mechanical test and numerical analysis. Mechanical properties of a rock, in general, would be strongly affected by mineral composition. In this reason REV of Youngju granite is determined by using stereoscopic microscope observation and homogenization numerical analysis. As the area of analysis model exceeds approximately 702$\textrm{mm}^2$(900 elements), the change of the mineral composition is not observed. The calculated results indicate that Young's modulus is fluctuated with increase of the number of elements in homogenization numerical analysis mesh. However, as the number of elements exceeds 1156 (area of about 900$\textrm{mm}^2$), Young's modulus does not change apparently.

• Proceedings of the Korea Contents Association Conference
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• 2005.11a
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• pp.123-128
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• 2005

Buk-myeon area in Changwon is located near Nakdong river and not short of quantity of river but the water quality and quantity is changed extremely by seasons, and Fe, Mn, Cu are found at the base rock underground water. Therefore, bank filtrated water developing is settled. At this research, Pilot-Plant is built to find out Fe and Mn are detected and eliminated by biological process and the ammonia is exceeded the drinking water quality criteria at the bank filtrated water while designing and facilitating the local water supply facilities at Buk-myeon area. Also, check results of the changed treatment process of automatic precipitating filter, which is producing and supplying drinking water, and analyzing the Biological Process Effectiveness by building and running Buk-myeon Water Treatment Facility, which could provide $10,000m^3/day$.

• Tunnel and Underground Space
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• v.21 no.6
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• pp.480-493
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• 2011

Dynamic rock property is one of most important parameters in design of earthquake-resistant structures. In this study, free-free resonant column test has been conducted to obtain dynamic Young's modulus, dynamic shear modulus, and damping ratio among dynamic properties with granite specimen of Chungnam Yeongi area. The dynamic properties obtained from this test were compared with the physical properties from static rock tests, and their relationship has been analyzed. From our study, it has been concluded that the dynamic Young's modulus and the dynamic shear modulus are linearly proportional to the elastic wave velocity. And also the damping ratio has been identified to be in non-linear inverse proportion to the elastic wave velocity.

• Tunnel and Underground Space
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• v.23 no.6
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• pp.506-520
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• 2013

While geothermal energy provides the only base-load power among renewable energy sources, its development has been carried out predominantly in volcanic area. EGS (Enhanced Geothermal System) is a ubiquitous technology that can allow the geothermal power generation virtually in any area. This manuscript introduces the current state-of-the-art of EGS development in the world and presents the hydraulic stimulation technology and associated microseismicity which are key technical component in EGS. Finally this paper suggests the key research areas required in Korea for further development of EGS.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.466-474
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• 2008

The purpose of this study was to comparatively analyze the measured values and modelling values when a sample mountain was cut and thereby, assess the fitness of the prediction model. For this purpose, the researcher analyzed the relationship between the groundwater levels measured at 7 monitoring holes set within the area of the underground flow prediction model and the levels of the groundwater monitoring holes before and after mountain cutting. As a result of this analysis, it was found that the MODFLOW program itself was limited and uncertain in terms of calibration of the modelling values. Since the model was based on the assumption that the same amount of rainfalls would permeate into the ground when the sample mountain area was cut up to 50m high, it was deemed inevitable that the result of modelling was different from the actual measurement.

• Tunnel and Underground Space
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• v.18 no.4
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• pp.263-271
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• 2008

3D seismic tomography technique was assessed for applicability of developed 3D tomography algorithm based on Fresnel volume in the dam-planned area. Reconstructed 3D tomogram based on Fresnel volume and Fast Marching Method(FMM) reveals similar velocity structure to the other geotechnical survey results. With the correlation analysis between RMR data and seismic velocity information, it could provide reliable information of rock mass rate. The applicability of 3D seismic tomography was verified in this study. It would be expected to apply 3D tomography with new developed first arrival calculation and inversion algorithm to the engineering field economically.

• Membrane and Water Treatment
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• v.10 no.4
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• pp.313-320
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• 2019

Increasing the concentration of nitrate ions in the soil solution and then leaching it to underground aquifers increases the concentration of nitrate in the water, and can cause many health and ecological problems. This study was conducted to evaluate the vulnerability of Meymeh aquifer to nitrate pollution. In this research, sampling of 10 wells was performed according to standard sampling principles and analyzed in the laboratory by spectrophotometric method, then; the nitrate concentration zonation map was drawn by using intermediate models. In the drastic model, the effective parameters for assessing the vulnerability of groundwater aquifers, including the depth of ground water, pure feeding, aquifer environment, soil type, topography slope, non-saturated area and hydraulic conductivity. Which were prepared in the form of seven layers in the ARC GIS software, and by weighting and ranking and integrating these seven layers, the final map of groundwater vulnerability to contamination was prepared. Drastic index estimated for the region between 75-128. For verification of the model, nitrate concentration data in groundwater of the region were used, which showed a relative correlation between the concentration of nitrate and the prepared version of the model. A combination of two vulnerability map and nitrate concentration zonation was provided a qualitative aquifer classification map. According to this map, most of the study areas are within safe and low risk, and only a small portion of the Meymeh Aquifer, which has a nitrate concentration of more than 50 mg / L in groundwater, is classified in a hazardous area.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.227-231
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• 2015

The focus of this study is on the accuracy in quantity estimates made by BIM for materials needed during construction. BIM-Revit Architecture 2014 is utilized to establish the information for an actual case to conduct estimates for the amount of reinforced concrete and formwork needed. The actual case is with a total construction area of 5,438 square meters and a total floor area of 31,623 square meters. The building commenced in December 2012 and the major structure has been completed in 2014. It is a RC structure with 4 stories underground, 12 stories above and 3 roof floors. The result shows that both of the quantity estimates of reinforced concrete and formwork are higher than that of actual use in the case. The estimate of reinforced concrete is higher than that of actual use by 2.18%, while the estimate of formwork is higher than that of the actual use by 13.04%. The results indicate that the estimate of reinforced concrete made by BIM has high accuracy, but the accuracy of the formwork estimate still needs improvement.

• Ocean and Polar Research
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• v.26 no.1
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• pp.23-32
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• 2004

As a baseline survey for long-term monitoring on environmental change around the Antarctic King Sejong Station, distribution pattern of Deschampsia antarctica Desv., a flowering plant newly colonized were investigated qualitatively and quantitatively in both austral summer 2002 and 2003. Dispersal of the seeds and vegetative leaves by skuas might lead to the colonization into this area from neighbors in Maxwell Bay. The pioneer populations were observed around ponds and a stream of the Sejong Point in January 2002, and the maximum dispersal area was four times expanded after a year. Most of the populations were formed on the stable and well-drained substrate, which consisted of moss carpet of Sanionia georgico-uncinata (65%) and pebbles (25%), while only a few young individuals were observed on the unstable and watertight silt-sandy area. Especially, S. georgico-uncinata was being effectively utilized as their primary substrate with the soft, coarse and water-contained leaves. Also the perennial mature plants of D. antarctica were mainly formed on the moss carpet rather than pebbles. A few individuals were grown on other mosses of Polytrichastrum alpinum, Bryum pseudotriquetrum, Pohlia cruda, and Conostomum magellanicum and on a liverwort of Cephaloziella varians. We expect that dispersal of D. antarctica and the following succession to grass field will be countinuously and dynamically proceeded in this area, with the characteristics of ecological niche against the initial moss populations, on the similar continuity of environmental conditions. The continuous observations are needed with establishment of database on environmental change of micro-habitats, e.g. the water content and nutrients of soil and the underground temperature and permafrost.