• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.71-78
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• 2002

The N-value from the standard penetration test(SPT) is affected by the magnitude of the rod penetration energy transmitted from the falling hammer as well as the geotechnical characteristics of the ground. Understanding of the striking energy efficiency in the SPT equipment is getting important for that reason. The energy efficiencies of the various type of equipment were investigated through field tests using the instrumented rod and wave-signal acquisition systems including the pile driving analyzer(PDA). The rod energy ratio, ERr was defined as the ratio of the energy delivered to the drilling rod to the potential free-fall energy of the hammer. It appears that the type of the hammer and lift/drop system had a strong influence on the energy transfer mechanism and ERr also varies according to the energy instrumentation system and the analysis methods.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2102-2107
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• 2007

GSHP systems are used for air-conditioning systems in commercial buildings, schools, and factories because of low operating and maintenance costs. These systems use the earth as a heat source in heating and a heat sink in cooling mode. Ground heat exchangers are classified by a horizontal and vertical type according to the installation method. Vertical type is usually constructed by placing small diameter high density polyethylene tube in a vertical borehole. Vertical tube sizes range from 20 to 40 mm nominal diameter. Borehole depth range between 100 and 200 m depending on local drilling conditions and available equipment. In this study, to evaluate the performance of single u-tube with bentonite grouting, single u-tube with broken stone grouting and double u-tube bentonite grouting of vertical ground heat exchangers, test sections are buried on the earth and experimental apparatus is installed. Therefore the heat transfer performance and pressure loss of these are estimated.

• Explosives and Blasting
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• v.28 no.1
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• pp.63-70
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• 2010

This study is investigated the extent of the noise and ground vibration in an adjacent zone of a cattle pen and an antiquated housing structures for judgement of the spot applicability on the extents of the noise and ground vibration of the rock-splitting method by an oil pressure. It is studied by measuring and analysing in an adjacent position the extents of the noise and ground vibration according to the work process of the rock-splitting method, such as drilling, rock-splitting, arranging rock, loading and by being compared with the permitted level on the noise and ground vibration fixed at the spot. To the results, it is identified that the influence to the noise has to be considered, even if the rock-splitting method is applied as an excavation method to lower a ground vibration by the classification on blasting method of the ministry of land, transport and marine affairs.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.247-254
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• 1999

In recent years there has been a steady increase in geoenvironmental engineering projects where geotechnical engineering has been combined with environmental concerns. Many of these projects involve some investigation of contaminant in the ground. There are many techniques such as geophysical, drilling, sampling, and pushing techniques for investigation of contaminated ground. The most rapidly developing site characterization techniques for geoenvironmental purposes Involve direct push technology, that is, penetration tests. In this study, the envi-cone penetrometer system is developed by modification of traditional cone penetration test. The electrical resistivity sensor, pH sensor, thermometer are installed in envi-cone penetrometer system. This envi-cone penetrometer system provides a continuous profile of measurements, and it is rapid, repeatable, reliable and cost effective.

• Nuclear Engineering and Technology
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• v.33 no.2
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• pp.156-165
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• 2001

A radiological safety assessment was performed for a hypothetical near-surface radioactive waste repository as a simple screening calculation to identify important nuclides and to provide insights on the data needs for a successful demonstration of compliance. Individual effective doses were calculated for a conservative ground water pathway scenario considering well drilling near the site boundary. Sensitivity of resulting ingestion dose to input parameter values was also analyzed using Monte Carlo sampling. Considering peak dose rate and assessment time scale, C-14 and T-129 were identified as important nuclides and U-235 and U-238 as potentially important nuclides. For C-14, the dose was most sensitive to Darcy velocity in aquifer The distribution coefficient showed high degree of sensitivity for I-129 release.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.245-250
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• 2007

The small loop EM method is a fast and convenient geophysical tool which can give shallow subsurface resistivity distribution. It can be a useful alternative of resistivity method in conductive environment. We applied the multi-frequency small loop EM method for the investigation of a soft ground landfill site which was constructed on a tideland since the resistivity of the survey area is extremely low. 3D resistivity distribution was obtained by merging 1D inversion results and shallow subsurface structure can be interpreted. By comparing the result with the drilling log and measured soil resistivity sampled at 16 drill holes, we can get lot of information such as groundwater level, thickness of landfill, salinity distribution, depth to the basement and etc.

• Journal of the Korean Geotechnical Society
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• v.31 no.12
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• pp.71-76
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• 2015

Recently, people are increasingly interested in horizontal directional drilling (HDD) to construct oil and gas pipeline and utility pipeline in the urban area as one of trenchless methods. One of major issues during the HDD is the collapse of borehole, which may be the potential causes of ground collapse. This study investigated the effect of mud pressure on the borehole stability, using finite element analysis. Since the borehole is being drilled with a certain angle, three dimensional analysis should be performed. The borehole stability was examined by applying two different types of mud pressures, i.e., uniform and non-uniform, to the exterior surface of borehole. The results show that the high mud pressure at the beginning of drilling, i.e., at shallow depth, causes the borehole collapse, whereas the borehole was stable even at high mud pressure as the drilling depth increases. It can be said that the determination of maximum mud pressure is strongly related to the drilling depth.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.466-469
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• 2007

Heat pumps are used for air-conditioning systems in commercial buildings, schools, and factories because of low operating and maintenance costs. These systems use the earth as a heat source in heating mode and a heat sink in cooling mode. Ground heat exchangers are classified by a horizontal type and vertical type according to the installation method. A horizontal type means that a heat exchanger is laid in the trench bored in 1.2 to 1.8 m depth. And a vertical type is usually constructed by placing small diameter high density polyethylene tube in a vertical borehole. Vertical tube sizes range from 20 to 40 mm nominal diameter. Borehole depth range between 100 and 200 m depending on local drilling conditions and available equipment. In this study, to evaluate the performance of single u-tube with bentonite grouting, single u-tube with broken stone grouting and double n-tube bentonite grouting of vertical ground heat exchangers, test sections are buried on the earth and experimental apparatus is installed. Therefore the heat transfer performance and pressure loss of these are estimated.

• Journal of the Korean Society for Railway
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• v.2 no.4
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• pp.9-19
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• 1999

The use of compaction grouting evolved in 1950's to correct structural settlement of buildings. Over the almost 50 years, the technology has been developed and is currently used in wide range of applications. Compaction grouting, the injection of a very stiff, 'zero-slump' mortar grout under relatively high pressure, displaces and compacts soils. It can effectively repair natural or man-made soil strength deficiencies in variety of soil formations. Major applications of compaction grouting include densifying loose soils or fill voids caused by sinkholes, poorly compacted fills, broken utilities, improper dewatering, or soft ground tunneling excavation. Other applications include preventing liquefaction, re-leveling settled structures, and using compaction grout bulbs as structural elements of minipiles or underpinning. In this paper, on the basis of the case history constructed in this year, a study has been performed to analyze the basic mechanism of the compaction grouting. Also, the effectiveness of the ground improvement and the bearing capacity of the compaction pile has been verified by the Cone Penetration Test(CPT) and Load Test. Relatively uniform compaction grouting column could be maintained by planning the quality control in the course of grouting. And, the Qualify Control Plan has been conceived using grout pressure, volume of grout and drilling depth.

• Journal of the Korean earth science society
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• v.36 no.1
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• pp.16-26
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• 2015

To investigate the applicability of physical prospecting technique in soft ground assessment, the resistivity monitoring data of 6 months are acquired. The Multichannel Analysis Surface Wave (MASW) has been additionally performed to identify the shear wave velocity and strength distribution of soft ground. Moreover, by using the Cone Penetration Test (CPT) and laboratory tests of drilling samples, a relationship with the physical prospect data is checked and the reliability of the physical prospect data is increased. Through these activities, the behavior patterns of soft soil are identified by long term monitoring, and the significant relationship between the shear wave velocity and laboratory tests has been confirmed, both of which can be useful in the surface wave exploration to evaluate the strength of soft ground. Finally, using the geostatistical method, 3-dimensional soil base distribution images are obtained about the combined physical prospecting data with heterogeneous data. Through the studies, the nature of entire area can be determined by long term resistivity monitoring for the soft ground assessment in wider area. It would be more economic and reliable if additional exploring and drilling samples can be analyzed, which can reinforce the assessment.