• Journal of Advanced Marine Engineering and Technology
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• v.35 no.7
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• pp.966-973
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• 2011

Power distribution onboard vessel is typically configured as ungrounded system due to the ability to continuously supply electric power even when an earth fault occurs. The impedance connections between 3 phase power lines and hull cause the line-to-hull voltages to become unstable and increased in case the impedances are unbalanced, bringing the situation susceptible to electric shock and deterioration of insulation material. Also the line-to-hull voltage can reach to a certain maximum value in the steady state depending on the distributed capacitances and grounding resistances between lines and hull. This study suggests how to find and calculate the maximum line-to-hull voltage in view of magnitude and phase angle based on the vector diagram.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2619-2627
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• 2009

The ground fault is occupying 70% among the total number of faults in ungrounded distribution power system. When the ground fault occurs in ungrounded system, the fault current is so small that it is hard to detect. But fault handling is very important because to continue power supply during fault conditions may cause the fault spreading and the distribution device in trouble. This paper presents the fault line detection method by using GPT signal detecting zero sequence voltage, and the fault section detection method by detecting whether GPT signal is disappeared or not during shifting normally open switch, which is connecting switch between distribution lines with open state in order to restore the outage area under emergency situation, and during isolating each section one by one which belongs to the fault line. This method is efficient because there is no whole power interruption during the fault section detection, and it is possible to perform both the fault section detection and the service restoration for the outage area at the same time, and it can apply to various distribution system configuration. Program for the fault restoration was developed applying proposed method, and it has been validated by applying to the pilot project of distribution automation system in Vietnam which has the ungrounded distribution system.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.113-117
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• 2003

The digital systems include the noise in power supply, ground and packaging due to a simultaneous switching of signal, signal reflections and distortions on single and multiple transmission lines. The requirement for the controlled impedance on a PCB can be both a critical success factor and a design challenge. So, the invented tool simulates the tracks controlled impedance with the test coupon. It can saves the design time and supports the economical PCB design.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.5-6
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• 2015

A GNSS based measurement system was constructed with not only the core sensors of a GNSS receiver, a TRS sensor and a soil moisture sensor but supplementary installation of power supply and radio communication for monitoring steep slope sites. The sensor combination extracts and transfers not only ground displacement in real-time but soil moisture content.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.229-232
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• 1988

Induced voltage causing disturbances on the communication lines of electric train is dealt with when the AT power supply system is employed. In the paper we obtain an algorithm to calculate the induced voltages on the communication lines in the AT system and an algorithm for the induced current in case of the accident that the line falls to the ground. These algorithms are developed to a package of computer programs and their validity was checked on a simulated system.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.149-153
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• 1999

As VLSI technology advances rapidly, the operating frequency of digital systems becomes very fast. In such a high-speed system, there are many factors that threaten signal integrity. The noise sources in digital system include the noises in power supply, ground bounce and packaging media and distortions on single and multiple transmission lines. This paper will present a technology survey useful in the design of Gigabit interconnection systems. Some case studies have been constructed which show the lossy transmission line effect of skin effect. dielectric loss, with backplane connectors using the theoretical and practical conditions.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.344-351
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• 1999

The safe operation of electro railways is greatly dependant on its protective systems. The system so-called Fault Protection Wire(FW) is now widely adapted to protect in AT feeding systems. It is connected between the feeder and trolley circuit to return the fault current to autotransfonmers at substation. This paper computed the distribution of fault currents at FW in the system and also evaluated the safety from electric shock when ground fault or flashover occur in the feeding system. The results show FW is useful to protect power supply network from fault in electric railways

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.283-287
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• 2005

In this paper, one general approach is proposed for the design of power system that can be applicable for next generation LEO satellite application. The power system consists of solar panels, battery, and power control and distribution unit(PCDU). The PCDU contains solar array modules, battery interface modules, low-voltage power distribution modules, high-voltage distribution modules, heater power distribution modules, on-board computer interface modules, and internal DC/DC converter modules. The PCDU plays roles of protection of battery against overcharge by active control of solar array generated power, distribution of unregulated electrical power via controlled outlets to bus and instrument units, distribution of regulated electrical power to selected bus and instrument units, and provision of status monitoring and telecommand interface allowing the system and ground operate the power system, evaluate its performance and initiate appropriate countermeasures in case of abnormal conditions. We review the functional schemes of the main constitutes of the PCDU such as the battery interface module, the auxiliary supply module, solar array regulators with maximum power point tracking(MPPT) technology, heater power distribution modules, spacecraft unit power distribution modules, and instrument power distribution module.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.7
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• pp.319-325
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• 2005

In order to analyze ground potential rise of grounding system installed in buildings, the hemispherical grounding simulation system has been designed and fabricated as substantial and economical measures. Ground potential rise(GPR) has been measured and analyzed for shapes of grounding electrode using the system in real time. The system is apparatus to have a free reduced scale for conductor size and laying depth of a full scale grounding system and is constructed so that a shape of equipotential surface is nearly identified a free reduced scale with a real scale when a current flows through grounding electrode. The system was composed of a hemispherical water tank, AC Power supply, a movable potentiometer, and test grounding electrodes. The test grounding electrodes were fabricated through reducing grounding electrode installed in real buildings such as rod type, mesh grid type. When a mesh grid type was associated with a rod type, GPR was the lowest value. The proposed results would be applicable to evaluate GPR in the grounding systems. and the analytical data can be used 0 stabilize the electrical installations and prevent the electrical disasters.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.4
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• pp.73-79
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• 2007

In order to analyze the potential rise of grounding systems installed in buildings, a hemispherical grounding simulation system was studied. Potential rise was measured and analyzed regarding the shape and distance of the grounding electrodes by using this system. The system was composed of a hemispherical water tank, AC power supply, a movable potentiometer, and test grounding electrodes. The potential rise was measured in real time by the horizontal moving probe of be potentiometer. The test grounding electrodes were fabricated through reducing the grounding electrode installed in real buildings such as the ground rod, grounding grid and so on. The potential rise was displayed in a two-dimensional profile and was analyzed regarding the shapes of the ground electrodes. The potential rise of the grounding grid combined with a ground rod was the lowest of every grounding electrode tested. The proposed results can be applicable to evaluating ground potential rise in grounding systems, and the analytical data can be used to stabilize the electrical installations and prevent electrical disasters.