• KEPCO Journal on Electric Power and Energy
• /
• v.2 no.4
• /
• pp.601-608
• /
• 2016

The electrical characteristics of the soil where a ground electrode is buried vary with regions, seasons and environmental factors. Electrical discharge in the vicinity of the ground electrode will occur differently and significantly affect the performance of the grounding system. It is necessary to analyze discharge and ionization characteristics of soils when the grounding system is designed. The aims of this investigation are to understand correlation between the soil ionization and the transient ground impedance. This paper presents the experimental results on the soil ionization parameters and the transient ground resistance due to the soil ionization around a hemispherical ground electrode stressed by lightning impulse voltages.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.04a
• /
• pp.105-110
• /
• 1998

The propose of this study is to examine the mechanical properties of mortar using ground granulated blast-furnace(GGBF) slag. In this study, the mortar replaced by varying fineness and content of GGBF slag is investigated through the change of compressive strength, chemical resistance and weight loss. As the result, it has been found that GGBF slag increase somewhat higher flow value and compressive strength. In addition, the chemical resistance of motar using GGBF slag shows higher flow that of motar not containing GGBF slag.

• Fire Science and Engineering
• /
• v.2 no.1
• /
• pp.21-28
• /
• 1988

This paper deals with the optimal use of the ELB (Electric Leakage circuit Breaks) for the protection of low voltage distribution system. Since the ELB is recently used together for grounding fault while only the ground resistance was used in the past, the analysis of ELB characteristics is indispensible. By the quantitative analysis and the setting of limit the ground resistance and the ELB is derived and then the optimal use of the ELB is expected to contribute to the system protection.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.12
• /
• pp.88-93
• /
• 2011

When the ground current is injected into the adjacent ground electrode, the potential interference is caused between ground electrodes, the ground potential interferences have been largely studied with power frequency fault currents. Many attempts to find the frequency-dependent grounding impedance report that the high frequency grounding impedance is very different with the ground resistance. This paper presents experimental data on the frequency-dependent potential interference effects in the vicinity of ground rod. The ground potential rises around the test ground rod of 4 or 6[m] were measured and discussed. As a result, the ground potential rises and potential interference factor are decreased with decreasing the grounding impedance. It was found that the lowering of grounding impedance is critical to reduce the ground potential interference effects.

• Journal of the Korean GEO-environmental Society
• /
• v.18 no.7
• /
• pp.13-20
• /
• 2017

Soil nailing is ground reinforcement method using the shear strength of ground and the pullout shear resistance force of nail. It is mainly used for reinforcement of cut slopes, earth retaining structures and retaining walls, etc. It may be designed considering the pullout resistance of nail in the case of earth retaining structure and retaining wall, but it should be designed considering not only pullout resistance but also shear and bending resistance in the case of slope. However, conservative designs considering only pullout resistance are being done and most of the studies are about increasing pullout resistance by improving of material, shape and construction method of nail. Actually, Shear bending deformations occur centering on the active surface in ground reinforced with the nail. The grout with relatively low strength is destroyed and separated from the reinforcing material. As a result, the ground is collapsed while reducing the frictional resistance rapidly. Therefore, it is necessary to develop the method to increase the shear resistance while preventing separation of nail and grout body. In this study, an experimental study was conducted on new soil nailing method which can increase shear resistance by forming protrusions through pressurized grouting after installing a packer on the outside of deformed bar.

• Journal of the Korea Institute of Building Construction
• /
• v.23 no.4
• /
• pp.349-358
• /
• 2023

This research aimed to enhance the initial strength of concrete that is mixed with ground granulated blast furnace slag, as well as to fortify its resistance to carbonation and chloride ion permeation. To achieve this, alkaline aqueous, produced through the electrolysis of potassium carbonate, was employed as the mixing water in the preparation of concrete. To substantiate the increment in initial strength, compressive strength measurements of the concrete were executed. Additionally, an accelerated carbonation test and a chloride ion permeation resistance test were undertaken. The results confirmed that the initial strength of the concrete, which utilized electrolysis alkaline aqueous as mixing water, exhibited an improvement in comparison to concrete mixed with conventional water. It was also verified that both carbonation resistance and chloride ion permeation resistance showed enhancements.

• Proceedings of the SAREK Conference
• /
• 2008.11a
• /
• pp.33-38
• /
• 2008

A ground-loop heat exchanger in a ground source heat pump system is an important unit that determines the thermal performance of a system and its initial cost. The Size and performance of this heat exchanger is highly dependent on ground thermal properties. A proper design requires certain site-specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This study was performed to investigate the effect of some parameters such as borehole lengths, various grouting materials and U-tube configurations on ground effective thermal conductivity. In this study, thermal response tests were conducted using a testing device with 9-different ground-loop heat exchangers. From the experimental results, the length of ground-loop heat exchanger affects to the effective thermal conductivity. Among the various grouting materials, the bentonite-based grout with silica sand shows the largest thermal conductivity value.

• JOURNAL OF ELECTRICAL WORLD
• /
• no.8 s.128
• /
• pp.6-9
• /
• 1987

• Journal of the Korean Geotechnical Society
• /
• v.32 no.1
• /
• pp.5-18
• /
• 2016

In this study, we grasped the resistance state of the back ground which had a notable influence on computing the lateral resistance of the laterally loaded pile group in the homogeneous ground by the model test. Resistance state was grasped as the depth of rotation-point, wedge failure angle, and wedge wing angle. The model experiment is performed by varying the width, spacing and number of piles and the relative density of sand in this study. According to the observation of the rear ground surface deformation of the piles in lateral load, rotation point ratio, wedge failure angle, and wedge wing angle of the front row were similar to those of the middle row; however, those of the back row were relatively smaller. The rotation point ratio, wedge failure angle and wedge wing angle of the piles in parallel were the same as those of a single pile. Based on the model test results, equations for estimation of the rotation-point, wedge failure angle, and wedge wing angle are proposed.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.10 no.5
• /
• pp.163-170
• /
• 2006

Recently, piezocone penetration test is frequently used in order to estimate the characteristics of soft ground with standard penetration test, generally used in the past. In this study, the correlation of standard penetration test, piezocone penetration test and driving resistance of vertical drain is analyzed in order to increase the confidence for determination of soft ground depth. As the results of each zone, the relation between standard penetration test and piezocone penetration test shows qc=(1.09~1.63)N at the soft ground, determined by 5/30 N value which is decided for soft ground criteria. And qc=(1.21~1.98)N was shown at the point of compressible layer, evaluated by the preconsolidation pressure. And driving resistance of vertical drain is $65{\sim}70kgf/cm^2$ which is equal to $10kgf/cm^2$ of cone penetration resistance.