• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.193-198
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• 2006

It takes a lot of time and effort to generate grids for numerical analysis of problems with ground effect because the relative attitude and height of airfoil should be maintained to the ground as well as the inflow. A low Mach number preconditioned turbulent flow solver using the overlap grid technique has been developed and applied to the ground effect simulation. It has been validated that the present method using the multi-block grid gives us highly accurate solutions comparing with the experimental data of the RAE 101 airfoil in an unbounded condition. Present numerical method has been extended to simulate ground effect problems by using the overlapped grid system to avoid tedious work in generating multi-block grid system. An extended method using the overlapped grid has been verified and validated by comparing with results of multi-block method and experimental data as well. Consequently, the overlapped grid method can provide not only sufficiently accurate solutions but also the efficiency to simulate ground effect problems. It is shown that the pressure and aerodynamic centers move backward by the ground effect as the airfoil approaches to the ground.

• 한국항공우주학회지
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• 제35권8호
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• pp.661-669
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• 2007

지면효과에 대한 수치해석을 위한 격자생성 과정에서 발생하는 어려움을 해소하기 위하여 중첩격자 기법을 이용한 수치해석 기법의 타당성에 대한 연구를 수행하고 그 신뢰성을 검증하였다. 지면효과가 있는 경우와 없는 경우 RAE 101 익형주위의 저속 난류 유동장에 대한 수치해석을 수행하였고 다중블록격자 기법과 중첩격자 기법을 적용한 수치해석 결과를 실험결과와 비교하였다. 이를 통하여 중첩격자 기법을 이용함으로써 지면효과에 대한 수치해석과정을 정확하고 격자생성 문제없이 효과적으로 수행할 수 있음을 보였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 추계학술대회 논문집
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• pp.193-196
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• 2008

In these days, large structures are constructed and bonded with ground grid Because the distances between mesh and auxiliary electrodes are not enough in downtown areas, it is very difficult to measure the ground resistance of large scale grounding electrode systems. Actually the auxiliary electrodes for test are installed in grounding grid. This paper present the experimental results of ground resistance and impedance according to the location of auxiliary electrode. As a result, we get much lower resistances and impedances than real values the auxiliary electrodes are placed in the ground grid. In case that the auxiliary electrodes are located in the ground grid the resistances are very low and reactance only is inductive component.

• 한국안전학회지
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• 제30권4호
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• pp.46-50
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• 2015

This paper describes the measurement and analysis of ground impedance according to arrangement of auxiliary probe around ground grid using the fall-of-potential method and the testing techniques to minimize the measuring errors are proposed. The fall-of-potential method involves passing a current between a ground electrode and a current probe, and then measuring the voltage between a ground electrode and a potential probe. To minimize interelectrode influences due to mutual resistances, the current probe is a generally placed at a substantial distance from the ground electrode under test. In order to analyze the effects of ground impedance due to the arrangement of auxiliary probe and frequency, ground impedances were measured in case that the arrangements of auxiliary probe were straight line, perpendicular line, and horizontal line. The distance of current probe was located from 10[m] to 200[m] and the measuring frequency was ranged from 55[Hz] to 513[Hz]. As a consequence, the ground impedance increases with increasing the distance from the ground electrode to the point to be tested, but the ground impedance decreases with increasing the frequency.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.65.2-65.2
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• 2010

Currently the variety of governmental business support and research for supplying solar energy have been actively progressed. As of now, however, There are no practical testing infrastructures of grid-connected photovoltaic system which test performance of solar power facility in domestic. Therefore, in KEPRI, there is in progress construction of practical testing ground of 500 kW class grid-connected PV System for developing the evaluation of the performance technology including the Module, PCS, and etc, that is the important instrument of the PV System, in Gochang area. It analyzed the site creation work for constructing the practical testing ground and new construction of control room and the unit standards, specifications and capacity of required equipment. For the system detailed design, configuration, instrument-specific parameters established, power generation predictions of Array Type and the components of testing ground are needed to build.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.63-65
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• 2003

The purpose of the study is to produce the surface ground temperature diagnostically using surface EBM with the use of GRID model in Geographic Information Systems (GIS). Certain characteristics have been analyzed for local slope effect, coastal effect and influence of high orographic aspect on the surface ground temperature. We present discussions on the meteorological responsibility for their temperature. The derived surface ground temperatures can be provided for comparison with those from satellite-based observ ation.

• 조명전기설비학회논문지
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• 제20권4호
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• pp.29-36
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• 2006

본 논문은 여러 가지 형상의 접지시스템에서 접지전극 상호간의 전위간섭에 대해 다루었다. 접지전극의 일정한 형상과 크기, 접지전극간 이격거리에 따른 전위상승과 전위간섭계수를 수조실험장치를 이용하여 측정하고, CDEGS 프로그램으로 해석하였다. 전위상승과 전위간섭계수는 접지전극의 이격거리, 접지전극의 형상과 크기에 강하게 의존한다. 격자형 접지전극과 격자형 접지전극 사이의 전위간섭은 격자형 접지전극과 봉형 접지전극 사이의 전위간섭보다 낮은 것으로 나타났다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2002년도 학술대회논문집
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• pp.303-306
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• 2002

This paper presents a novel method for measuring the ground impedance in grounding systems. A square wave current was injected to the main grounding grid through auxiliary electrode, and the test current and ground potential rise(GPR) were measured using the band-pass filter. Ground impedance was calculated from the sinusoidal waveforms of the test current and GPR in frequency range of 20~2100Hz. Also the resistance and reactance component of ground impedance were analyzed.

• 조명전기설비학회논문지
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• 제26권3호
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• pp.53-60
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• 2012

The fall-of-potential method is commonly used in measuring the ground resistance of large-scaled grounding system and the current and potential auxiliary electrodes are horizontally arranged. Because the distances between the ground grid to be tested and auxiliary electrodes are limited in downtown areas, it is very difficult to measure accurately the ground resistance of large-scaled grounding system. In this paper, the fall-of-potential method of measuring the ground resistance with the vertically-placed current and potential auxiliary electrodes was examined and discussed. The validity and good accuracy of the proposed method of measuring the ground resistance were confirmed through various simulations and actual tests carried out in uniform and two-layer soil structures.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1673-1677
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• 2008

A method of construction with a basis treatment that uses a latticed bamboo mat puts bamboo's peculiarity and bamboo mat's bending substance to use, and a latticed bamboo mat equally distributes to embankment loading in a basis ground. Therefore it prevents ground destruction by an ill-balanced load and an irregular ground subsidence, and it makes safety system. This investigation make progress a soil box model by a dredged reclamation ground of west and south sea at domestic area, and make a comparative study and analyze the strengthening effect based on a grid size of a bamboo-mat and ground failure that it will use in the field.