• Journal of the Korean GEO-environmental Society
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• v.16 no.12
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• pp.13-22
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• 2015

Developed ground cavity due to leakage of decrepit old sewer pipe causes ground surface settlement and brittle fracture of pavement. Recently, for 5 years, frequency of occurrence of ground subsidence phenomenon tends to increase rapidly and/or steadily. It is difficult to investigate ground surface settlement and/or subsidence in urban area because most ground surfaces are covered with asphalt or concrete pavement. In this research, therefore, ground surface settlement, influence zone and settlement of sewer pipe were analyzed using finite element method. Not only reinforced effect of pseudo-plastic backfill that is applied to prevent ground surface settlement or subsidence spot, was compared and analyzed using numerical analysis program, but also direct shear test was carried out to determine strength parameters of pseudo-plastic backfill.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.3
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• pp.211-220
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• 2002

CGS(Compaction Grouting System) is widely used in reinforcement of structural foundation and ground improvement in soft ground. But the effects of ground improvement depending on the type of soil must be studied in order to adopt in various soils (granular soil and cohesive soil). In this study, characteristics of ground improvement (the increase of N value, increase in unit weight, vertical displacement on the ground surface) by CGS method was compared through two cases that were performed in granular and cohesive soil. The results show that the closer to the grout hole, the more increase in N value and this trend appear distinctly in granular soil. Unit weight of ground increase largely near by the grout hole and decrease in far from it independently of the soil type. The vertical displacement on the ground surface appeared in smaller area in case of granular soil than cohesive soil.

• Advances in environmental research
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• v.9 no.3
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• pp.151-160
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• 2020

Water quality demonstrates physical, chemical and biological characteristics of water. The quality of surface and groundwater is currently an important concern with population growth and industrialization. Over exploitation of water resources due to demand is causing the deterioration of surface water and ground water. Periodic water quality testing must be carried out to protect our water resources. The present research analyses the spatial variation of surface water and groundwater in and around the lakes of Hyderabad. Twenty-Seven lakes and their neighboring bore water samples are obtained for water quality monitoring. Samples are evaluated for specific physico-chemical parameters such as pH, Total Dissolved Solids (TDS), Cl, SO₄, Na, K, Ca, Mg, and Total Hardness (TH). The spatial variation of water quality parameters for the 27 lakes and groundwater were analysed. Correlation and multiple regression analysis were carried out to determine comparative study of lake and ground water. The study found that most of the lakes were polluted and this had an impact on surrounding ground water.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.4
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• pp.117-123
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• 2011

Lightning and switching surges propagating through the grounding conductors lead to transient overvoltages, and electronic circuits in information technology systems are very susceptible to damage or malfunction from the electrical surges. Surge damages or malfunctions of electrical and electronic equipment may be caused by potential rises. To solve these problems, it is very important to evaluate the ground surface potential rises and hazardous voltages such as touch and step voltages at or near the grounding systems energized by electrical surges. In this paper, the performance of grounding systems against the surge current containing high frequency components on the basis of the actual-sized tests is presented. The ground surface potential rises and hazardous voltages depending on impulse currents for vertical or horizontal grounding electrodes are measured and analyzed. Also the touch and step voltages caused by the impulse currents are investigated. As a result, the ground surface potential rises, the touch and step voltages near the grounding electrodes are raised and the conventional grounding impedances are increased as the front time of the injected impulse currents is getting faster.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.1
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• pp.145-153
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• 1990

The relationship between ground surface settlements and wall displacements associated with excavation is analysed by the results of model test of anchored sheet-piles in loose sand. The effect of wall restriction at the toe, anchor slope, wall rigidity, and excavation level on settlement of ground surface and wall displacement are considered for model test. The results of model test are compared with the theory and the results of field measurement of braced wall. The results of analysis are shown by fitted regression equations that may be used for prediction of ground surface settlement adjacent to anchored sheet-piles. It is found that wall displacement and ground surface settlement associated with excavation are different from the supporting methods.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.3
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• pp.17-25
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• 1997

This paper aims to clarify the effects of grinding conditions on the grinding force, ground surface and chipping size of workpiece in surface grinding of various ferrites with the resin bond diamond wheel. The main conclusions obtained were as follows: In a constant peripheral wheel speed, the specific grinding energy is fitted by straight lines with grinding depth coefficient($\delta$) in a logarithmic graph. The effect of both depth of cut and workpiece speed on grinding energy becomes larger in the order of Mn-Zn, Cu-Ni-Zn and Sr. When using the diamond grain of the lower toughness, the roughness of the ground surface becomes lower. The ground surfaces show that the fracture process during grinding becomes more brittle in the order of Sr, Mn-Zn and Cu-Ni-Zn. The chipping size at the corner of workpiece in grinding increases with the the increases of the depth of cut and workpiece speed, and the decrease of peripheral wheel speed. The effect of both depth of cut and workpiece speed on chipping size becomes more larger in the order of Sr, Mn-Zn and Cu-Ni-Zn.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.2
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• pp.69-76
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• 2009

Infiltration is the process of water penetrating from the ground surface into soil. Infiltration plays an important role on affecting ground water surface and surface flow during rainy season. The amount of infiltration water would be decreased as the urbanization would increase. Such phenomenons would make streamflow decrease or stream run dry. In this study the cumulative infiltration and the infiltration capacity of ground surface have been determined by the field experiment at three sites in the Hankyong National University, Korea. Three type pervious pedestrian blocks of the cumulative infiltration and the infiltration capacity have also been determined at the same site of the ground surface. It has been shown that one of three type blocks in terms of infiltration capacity is almost same as that of ground surface. The Kostiakov type has been adopted to determine the cumulative infiltration and the infiltration capacity for each site. The Horton type has been also adopted to determine the cumulative infiltration and the infiltration capacity. The value of parameter k for each site is determined and soil type would be identified corresponding to the value of parameter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.4
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• pp.97-103
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• 2011

The most important object of grounding systems is to protect human being from electric shock. Touch and step voltages are measured to evaluate the performances of grounding systems. Dangerous voltages have been largely studied by the power frequency fault currents, on the other hand, the ground current containing the high frequency components and surge currents haven't been considered. Many attempts about the grounding impedances reported in these days show that the performance of the grounding systems in high frequency range is very different with the ground resistance. It is necessary to analyze the dangerous voltages formed by the ground currents containing high frequency components. In this paper, the ground surface potential rises near the vertical and horizontal grounding electrodes are measured at the frequency of 100[Hz], 30[kHz], and 100[kHz]. Dangerous voltages are investigated with the frequency-dependent grounding impedance. As a result, the ground surface potential rise is increased as the grounding impedance increases. Touch and step voltages near the grounding electrode whose impedance increases with the frequency are sharply raised.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.168-171
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• 2001

It is a common practice to extract water from the ground for domestic, agricultural or industrial uses or to lower the groundwater level for construction work. An accurate prediction of ground settlement Is sometimes crucial when groundwater is pumped. This case study have shown that drawdown of the groundwater table may cause ground subsidence. Many settlement gauges was installed in the vicinity of a pumped well to measure the surface settlement. The relationships between the level of groundwater drop and surface settlement is investigated In this research.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.211-219
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• 2000

This paper simulated surface grinding process with statistically simulated grinding wheel topography, considering ridge formation phenomenon when grain scratch workpiece. Wheel grain is modeled as hybrid sphere and cone. Grinding wheel characteristic was evaluated with stylus by expanding the scanning region of the profilometer from a straight line to a plane. Each grain's diameter and semi-angle are assumed as normal distribution, each grain's protrusion height from wheel plane is assumed gamma distribution. So grinding wheel is simulated with grain's position randomly distributed without overlapping. Ground surface is 3-dimensionally simulated considering ridge formation of workpiece by each grain's cutting, and then surface profile and surface roughness parameters are compared with real ground workpiece.