• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.583-588
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• 2014

In this study, there are examined to the grounding of lightning protection system and electrical continuity tests in the field. The standard for lightning protection system is different design or construction according to the characteristics of the structure. Ground is measured and compared at least four locations. According to the measured results in the field, the sampled values of the ground resistance are measured $5{\Omega}$ or less and the difference between each value is suitable as $0.2{\Omega}$ or less. The values of the electrical continuity test between ground and metal bodies are measured 3 groups such as isolated portion, the mechanical contacted portion, and the electrical continuity portion measuring $0.2{\Omega}$ or less. It is measured to be less than $0.2{\Omega}$ at all in metal bodies of underground. A metal body installed inside the structure is not isolated, but the resistance values are higher than $0.2{\Omega}$. Therefore, It must be carried out the structure having lightning protection system confirm the LPL(lightning protection level) and design the strategy.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.142-147
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• 2007

This paper presents the distributions of ground surface potential rises as functions of soil structure and buried depth of ground rod. To propose fundamental data relevant to the reduction of electric shock of human beings due to ground surface rise, the ground surface potential rises near the ground rod were computed and measured. Ground surface potential rises near ground rod strongly depend on the soil structure, and an increase of the buried depth of ground rod results in a decrease of the ground surface potentials. The maximum ground surface potential appeared at the just above point of ground rod. Also, the measured results were in reasonably agreement with the data computered by grounding analysis program.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.4
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• pp.56-61
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• 2009

This paper presents the ground surface potential profiles and hazard voltages around the metallic structure connected to a small-sized model ground electrode. Because it is very difficult to draw valid conclusions concerning a general grounding problem from actual field data, scale model tests can be used to determine the touch and stop voltages and surface potential profiles around ground electrode. In this work, a hemispherical vessel with a diameter of 1,100[mm] was employed to simulate uniform soil. As a result, the ground surface potential around the ground electrode was significantly raised In particular the ground surface potential at the just upper point of ground rod was higher than other points. When the buried depth of ground rod is increased, the ground surface potential and step voltage were lowered but the touch voltage was elevated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.83-89
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• 2018

In this study, the settlement of concrete rectangular pyramid foundation on soft ground is investigated based on a finite element analysis. considering the grounding load and the grounding area of square pyramid foundation, we compensate the insufficient design bearing capacity and investigated the effect of settlement by load. Based on this study, it is found that the rectangular pyramid foundation shows the smallest settlement of three different type of foundations. As a result of this study, it was resulted that the square pyramid foundations were more effective than the crushed stone foundations by 18%. These results show that the ground pressures of the square pyramid bases are divided into horizontal and vertical stresses, so it is analyzed that the horizontal stress builds up the rigid ground on the foundation of the structure and distributes the load widely to increase the resistance to the overhead load.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.434-439
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• 2010

This study fabricated a simulation facility which reduced the structure of a current distribution line to 50:1 in order to analyze the induced lightning shielding effect of a 22.9kV-Y distribution line according to ground resistance capacity, grounding locations, etc. When installing an overhead ground wire, the standard for grounding a distribution line with a current of 22.9kV-Y requires that ground resistance in common use with the neutral line be maintained less than $50\Omega$every 200m span. The reduced line for simulation had 7 electric poles and induced lightning was applied to the ground plane 2m apart from the line in a direction perpendicular to it using an impulse generator. If induced voltage occurred in the line and induced current flowed through the line due to the applied current, the induced voltage and current of the 'A' phase were measured respectively using an oscilloscope. When all 7 electric poles were grounded with a ground resistance of less than $50\Omega$ respectively, the combined resistance of the line was $7.4\Omega$. When an average current of 230A was applied, the average induced voltage and current measured were 1,052V and 13.8A, respectively. Under the same conditions, when the number of grounding locations was reduced, the combined resistance as well as induced voltage and current showed a tendency to increase. When all 7 electric poles were grounded with a ground resistance of less than $100\Omega$, the combined resistance of the line was $14.9\Omega$. When an average current of 236A was applied, the average induced voltage and current of the 'A' phase calculated were 1,068V and 15.6A, respectively. That is, in this case, only the combined resistance was greater than when all 7 electrical poles were grounded, and the induced voltage and current were reduced. Therefore, it is thought that even though ground resistance is slightly higher under a construction environment with the same conditions, it is advantageous to ground all electric poles to ensure system safety.

• Journal of Ocean Engineering and Technology
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• v.25 no.3
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• pp.1-10
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• 2011

This paper estimates the residual longitudinal strength of a damaged double hull VLCC (Very Large Crude Carrier) under combined vertical and horizontal bending moments using Smith's method. The damage estimated in this study occurred due to collision or grounding accidents. The effects of the randomness of the yield stress, plate thickness, extent of damage, and the combination of these three parameters on the ultimate hull girder strength were investigated. Random variables were generated by a Monte Carlo simulation and applied to the double hull VLCC described by the ISSC (International Ship and Offshore Structures Congress) 2000 report.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.305-308
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• 2004

There are ground facility of maintenance in house electric facility of infra maintenance electric home appliances having used multifariousness in house, that use electric energy of common source for equipment. The body of building such as the reinforced concrete construction is structurally united, and the electric resistance is also small. It is possible that those foundations have contacted the ground at large surface area and that it substitutes the building construction body for the earth electrode. This is called "the structure earthing". This method has been defined at electrical facilities technical standards and KS in our country, and it has been used in various quarters practically. However, in our country, there is no example of using the foundation of the house as substitution earth electrode practically, and the means of the evaluation as electrode has not been established either. Then, in this paper, basic research for utilizing foundation of the house as substitution earth electrode is carried out.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.584-587
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• 2007

PCS를 비롯하여 WLAN, DMB, W-CDMA, UWB 등의 무선통신 서비스가 증가함에 따라 안테나 동작 대역폭의 광대역화가 더욱 요구된다. 1/4 파장 선형 모노폴 안테나는 구조가 간단하고 전방향성을 갖는 복사특성으로 인하여 가장 널리 사용되는 안테나 중의 하나이다. 모노폴 안테나의 광대역화를 위해서 일반적으로 원통의 직경을 증가시키는 방법을 사용하지만, 평면 모노폴에 적용된 스텝 기법을 적용하여 광대역 특성을 얻을 수 있다. 그러나 스텝 모노폴 자체는 광대역 특성을 나타내지 않으며, 접지면에서도 일정 형태의 스텝 돌출부위가 필요하게 된다. 본 논문에서는 그라운드면의 볼록 계단 구조가 모노폴 안테나의 대역 특성에 미치는 영향을 분석하여 최적의 안테나 급전구조를 도출하고자 한다. 결과의 검증을 위해서 소프트웨어 시물레이션 및 측정결과를 제시한다.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.280-281
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• 2006

This paper was analyzed fundamental about electrical characteristic of concrete to practical use base of building as Substitution Ground Electrode and Artificial Ground Electrode. 1) Gravel or Sand has a function that makes increase Resistivity of Concrete and Cement has a function that makes decrease Resistivity of Concrete. 2) Moisture Increase Work is so hard because of dry of Block but the Resistivity was decreased when the moisture of Concrete Block was gradually increased. 3) According to the measurement result of moltar and concrete block, ratio relation of Resistance and Resistivity of each block was thirty-fold difference.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.290-292
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• 2003

The intake tower of D-dam located in a mountainous area positioned in the left side of the dam and its structure installed alone on the water surface then, can become target of direct lightening. To protect the intake tower from the direct lightening and indirect-lightening, lightening rod installed in the top area of the intake tower and ground pole laid under the surrounding ground. however, because the surrounding ground almost consists of a rock, it is very difficult to obtain the grounding resistance. It is main object to examine the construction plan of the optimum lightening rod equipment and ground pole with measuring the earth specific resistance of the around of the intake tower which is the scheduled area to lay the ground pole with the Wenner's 4-electric pole method and the Schlumberger's method. and using the analysis tool, ESII.