• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.347-350
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• 2009

The latticed mesh grounding is compared with the diagonal mesh grounding. In the result, The latticed mesh grounding better than the diagonal mesh grounding at the maximum touch voltage, the grounding resistance and the total length of conductors.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.116-124
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• 2006

No matter how the equally spaced grounding grid is designed there are many problem. The best-fitted design for unequally spaced grounding grid is a part that must be considered. This paper Suggest a new way of calculation for grounding grid space of ground conductor by an algebraic function control(The first-order function, Root function, Polynomial function etc.) and on the optimal spaced grounding conductor that make the under 2[%] between maximum potential and minimum potential.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.1
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• pp.47-61
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• 2013

This study compares the Residual ultimate longitudinal strength - grounding Damage index (R-D) diagrams produced by two analysis methods: the ALPS/HULL Intelligent Supersize Finite Element Method (ISFEM) and the design formula (modified Paik and Mansour) method - used to assess the safety of damaged ships. The comparison includes four types of double-hull oil tankers: Panamax, Aframax, Suezmax and VLCC. The R-D diagrams were calculated for a series of 50 grounding scenarios. The diagrams were efficiently sampled using the Latin Hypercube Sampling (LHS) technique and comprehensively analysed based on ship size. Finally, the two methods were compared by statistically analysing the differences between their grounding damage indices and ultimate longitudinal strength predictions. The findings provide a useful example of how to apply the ultimate longitudinal strength analysis method to grounded ships.

• Journal of the Korean Society of Marine Environment & Safety
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• v.4 no.2
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• pp.1-12
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• 1998

This paper descirbes a series of numberical simulations of grounding accidents of four 40,000 DWT Conventional and Advanced Double Hull tanker bottom structures using LS/DYNA3D. The overall objective of this study is no understand the structural failure and energy absorbing mechanisms during grounding events for candidate double hull tanker bottom structures, which lead to the initiation of inner shell rupture and cause the kinetic energy dissipation to bring the ship to a stop. These nuberical simulations of the grounding events will contribute to future improvements in tanker safety at the design stage.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.6 no.5
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• pp.45-49
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• 1992

The transient characteristics of grounding systems are very important in the insulation design of electrical installations and depend on the shape and size of electrodes, soil resistivity and the magnitude and wave of the injection current. This paper establishes an algorithm to compute the surge impedance of two or more grounding systems using the Laplace Transformation technique and deals with the analysis of the transient characteristics on grounding systems.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.6
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• pp.298-306
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• 2002

We performed an safety evaluation on constructing of a common grounding system for electrical railway in view of its efficacy and technical fit. In order to compare the conventional grounding method, which has been individually conducted, with the common grounding with all ground wires connected in common to the counterpoise buried below the surface of the earth in parallel with rail, we set up scenarios with several cases of fault and load conditions in Chungbuk railway sections with the common grounding system. Based on models for railway conductors including the grounded system, line Parameters of railway power system are computed. The circuit model for power system with up and down lines, auto-transformers and railway substations is used to compute impedances of counterpoise and substation ground net. For each scenario with faults and operation conditions of railway, the induced potentials on signal and communication lines are also computed. It is shown that the common grounding for Chungbuk railway is superior experimentally to the conventional method in three respects: (1) the lower rail potentials during operation of railway in line, (2) the lower rail potentials for short-circuit faults between catenary and rail, and (3) the lower stress voltages on signal and communication lines for short-circuit or ground faults. The analysis results confirm that the grounding system for electric railway is required to be built by the common grounding and be evaluated on its safety in design.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.9
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• pp.57-63
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• 2012

The basic purpose of grounding is for human safety and normal operation of system related to electrical shock hazard by faults of electrical equipments. A grounding electrode is defined as a conducting element that connects electrical systems and/or equipment to the earth. The lowest possible resistance connection to the earth is sought from the grounding electrode. The grounding electrode is the foundation of the electrical safety system. The resistance to ground of vertical electrodes buried in the two deference soil structures has been analyzed for a length of electrodes and soil parameters. The equation of ground resistance of vertical electrodes are Tagg's equation for uniform soil models, and modified equation of Dwight equation for two-layer soil model. In this paper, compared with results of two equations are calculated values of vertical electrode in uniform and two-layer soil models.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.6
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• pp.108-114
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• 2011

In order to mitigate the possible hazards from electric shock due to the touch and step voltages, the high resistivity material such as gravel is often spread on the earth's surface in substations. When the grounding electrode is installed in two-layer soil structures, the surface layer soil resistivity is different with the resistivity of the soil contacted with the grounding electrodes. The design of large-sized grounding systems is fundamentally based on assuring safety from dangerous voltages within a grounding grid area. The performance of the grounding system is evaluated by tolerable touch and step voltages. Since the floor surface conditions near equipment to be grounded are changed after a grounding system has been constructed, it may be difficult to determine the tolerable touch and step voltage criteria. In this paper, to propose an accurate and convenient method for evaluating the protective performance of grounding systems, the propriety of the method for evaluating the current flowing through the human body around on a counterpoise buried in two-layer soils is presented. As a result, it is reasonable that the grounding system performance would be evaluated by measuring and analyzing the current flowing through the human body based on dangerous voltages such as the touch or step voltages and the contact resistance between the ground surface and feet.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.60-66
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• 2010

Mesh grounding electrodes in Korea and abroad are designed as lattice-shaped equidistance grounding grids. In case of a lattice-shaped grounding Grid, however, there is a problem of higher touch voltage at the corner of the grid relative to the center. To overcome this problem, we used oblique-shaped equidistance grounding grid to reduce the area of the corner where mesh voltage occurs. As a result the mesh voltage was reduced. Therefore, this paper suggests the use of oblique-shaped grounding grid instead of the existing lattice-shaped ones. It applied the same grounding design dimensions for both lattice-shaped and oblique-shaped grounding grids, compared and analyzed mesh voltage, GPR, ground resistance, total length of grounding conductor, verified that oblique-shaped grounding grid is superior to the lattice-shaped.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.905-907
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• 1996

Current design standard of substation grounding systems is primarily concerned with conventional outdoor substations. But in case of 154kV substations in the nation, almost all are indoor-type GIS substations. So there became to be something not proper for application of present design standard to indoor-type substations. In this paper, as a preliminary stage of drawing-up of the grounding system design standard which concerned with in-door-type substions, issues of current design standard are mentioned and directions of improvement are also presented.