• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.98-105
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• 2014

Soil discharges near the ground rod play an important role to reduce the ground potential rise and the ground impedance and to help the fault current to spread into the earth. This paper presents the effects of soil discharges on the transient and conventional ground impedances when the lightning impulse voltage was applied to a ground rod with radial needles. The current-voltage (I-V)curves and transient ground impedance curves were calculated based on the measured current and potential traces. Soil discharge behaviors related to I-V curves and transient ground impedance curves were analyzed as a function of the magnitude of lightning impulse voltages. As a result, the soil discharges occurred near the ground electrode contribute to the reduction of conventional ground impedance and limits the ground potential rise effectively under lightning impulse voltages.

• ETRI Journal
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• v.30 no.1
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• pp.101-112
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• 2008

In this paper, we present a method to customize the ground color in outdoor sports video to provide TV viewers with a better viewing experience or subjective satisfaction. This issue, related to content personalization, is becoming critical with the advent of mobile TV and interactive TV. In outdoor sports video, such as soccer video, it is sometimes observed that the ground color is not satisfactory to viewers. In this work, the proposed algorithm is focused on customizing the ground color to deliver a better viewing experience for viewers. The algorithm comprises three modules: ground detection, shot classification, and ground color customization. We customize the ground color by considering the difference between ground colors from both input video and the target ground patch. Experimental results show that the proposed scheme offers useful tools to provide a more comfortable viewing experience and that it is amenable to real-time performance, even in a software-based implementation.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.109.1-109.1
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• 2012

In the past few years, two-planet circumbinary systems (e.g., HW Vir, NN Ser, DP Leo and HU Aqr) have been detected around short-period eclipsing binaries using ground-based telescopes. The existence of these planets has been inferred by interpreting the O-C variations of the mid-eclipse times. We have tested the orbital stability of these systems and propose to use Light Travel Time Effect (LITE) to detect such circumbinary planets from the ground. We generated synthetically the LITE signal of a two-planet circumbinary system with the aim to apply an analytic LITE model to recover the underlying synthetic system. To mimic a degree of realism inherent to ground-based observations, we added to the synthetic LITE data white noise with a Gaussian distribution and sampled the synthetic LITE signal randomly. We successfully recovered the original system demonstrating that two-planet circumbinary systems can be detected using ground-based telescopes, provided the timing measurements of the mid-eclipses are sufficiently accurate and the observing baseline is long enough to ensure a sufficient coverage of all involved periods. We used HU Aqr as a test system and applied our model to its proposed planetary bodies considering near-circular orbits. We present the results of our calculations and discuss the LITE-detectability of a HU Aqr-like system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.663-668
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• 2008

Recently, World Radio Conference(WRC)-2007 approved the ultrawide bandwidth of 500 MHz for the use of spaceborne synthetic aperture radar in X-band for the EESS(Earth Exploration Satellite Service) in order to improve the SAR imaging resolution. It is concerned about the interference impact from the spaceborne SAR that may cause to most of ground radars due to the extended ultra wideband. In this paper, in order to predict the interference impact of the ground-based radar from the spaceborne radar, radar interference model is presented using radar characteristic parameters by taking into account the operating environments of the spaceborne and ground based radar in the time, space, and spectrum domains. Using the spaceborne SAR model of TerraSAR-X and ground radar model of meteorological radar recommended by ITU-R, the interference impact was assessed through the computer simulation to see the possible interference impact of the ground based radar operating in the Korean peninsula.

• Journal of the Korean GEO-environmental Society
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• v.22 no.12
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• pp.33-40
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• 2021

The deterioration of underground facilities, disturbance of the ground due to underground development activities, and changes in ground water can cause ground subsidence accidents in the urban areas. The investigation on the geotechnical and hydraulic factors affecting the ground subsidence accident is very significant to predict the ground subsidence risk in advance. In this study, an analysis DB was constructed through 3D ground modeling to utilize the currently operating geotechnical survey information DB and ground water behavior information for risk prediction. Additionally, using these results, the relationship between the actual ground subsidence occurrence history and ground conditions and ground water level changes was confirmed. Furthermore, the methodology used to visualize the risk of ground subsidence was presented by reconstructing the engineering characteristics of the soil presented according to the Unified Soil Classification System (USCS) in the existing geotechnical survey information into the internal erosion sensitivity of the soil, Based on the result, it was confirmed that the ground in the area where the ground subsidence occurred consists of more than 40% of sand (SM, SC, SP, SW) vulnerable to internal erosion. In addition, the effect of the occurrence frequency of ground subsidence due to the change in ground water level is also confirmed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1778-1783
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• 2009

Ground impedance for the large grounding system is measured according to the IEEE Standard 81.2 which is based on the revised fall-of-potential method of installing auxiliary electrode at a right angle. When the auxiliary electrodes are located at an angle of $90^{\circ}$, the ground impedance inevitably includes the error due to earth mutual resistance. In this paper, in order to accurately measure the ground impedance of vertically-driven ground electrodes, error rates due to earth mutual resistance are evaluated by ground resistance and ground impedance measuring devices and compared with calculated values. As a result, the measured results are in good agreement with the computed results considering soil layer with different resistivity. The error rates due to earth mutual resistance decrease with increasing the length of ground electrode in the case that the ratio of the distance between the ground rod to be measured and the auxiliary electrodes to the length of ground electrode(D/L) is same. The ground impedance should be measured at the minimum distance between the auxiliary electrodes that will have an estimated measurement accuracy due to earth mutual resistance.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.285-287
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• 2007

This paper describes that the effect on the other system is generated by the single line to ground fault of the underground transmission systems and distribution systems established the common ground in trefoil. Each system is modeled by EMTP/ATPDraw and the system carry out simulations according to the various values of common ground to analyse. In this study, the result of analysis based on simulation suggests protection method and ground system of each system.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1448-1453
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• 2008

This paper deals with the estimation methods of ground-borne noise generated by subway. Generally, numerical method using by ground model is used to prediction of ground borne noise. However, this method is needed a lots of time to make an analysis and model. In this paper, we describe empirical formula that is based on experimental data for subway and estimate the ground-borne noise propagated from underground station that is builded in the near future to building.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.211-214
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• 2004

The measurement system of ground impedance is based on a computer aided technique. The magnitude and phase of ground impedance were determined by the novel measurement and analysis using the revised fall-of-potential method. The ground impedances of the ground rod of 30 m long are considerably dependent on the frequency. The ground impedance is mainly resistive in the frequency range of 3-20 kHz. At higher frequencies, the reactive components of the ground impedances are no longer negligible and the inductance of the ground rod was found to be the core factor deciding the ground impedance.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.10
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• pp.983-988
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• 2011

This paper presents a robust method for ground plane detection in vision-based applications based on a monocular sequence of images with a non-stationary camera. The proposed method, which is based on the reliable estimation of the homography between two frames taken from the sequence, aims at designing a practical system to detect road surface from traffic scenes. The homography is computed using a feature matching approach, which often gives rise to inaccurate matches or undesirable matches from out of the ground plane. Hence, the proposed homography estimation minimizes the effects from erroneous feature matching by the evaluation of the difference between the predicted and the observed matrices. The method is successfully demonstrated for the detection of road surface performed on experiments to fill an information void area taken place from geometric transformation applied to captured images by an in-vehicle camera system.