• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.288-292
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• 2006

Usually, equations that calculate ground resistance of earth electrode was already informed well by form of earth electrode. But, when apply on the spot because general expressions are very insufficient at point that calculate exact ground resistance value by variation of earth electrode, and constant value that corrective coefficient for ground resistance calculation is fixed regardless of change of the earth resistivity specially is presented, it is actuality that difficulty is. Therefore, in this study, about these problem, proposed corrective coefficient for calculation of ground resistance according to change of the earth resistivity.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.285-292
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• 2004

Earth Anchor method as a supporting system is widely used in the large scale deep excavation of urban areas or slope excavation project. Considering the application frequency of that method and catastrophe of that method under unproper construction management, we can find out many problems relevant to the domestic design and construction management of earth anchor method. When we encounter the cases of rapid increments and various decrements in earth anchor axial forces, considering the characteristic of earth anchor method, it is an essential point to catch the reasons and to prepare countermeasures. This article introduces two actual monitoring examples based on the close analyses of measured data in a typical large scale deep excavation project and slope excavation project. One is a rapidly increasing case of earth anchor axial forces with the continuous advance of incremental deformation in a geological layer interface. And another is a decreasing case of earth anchor axial forces with the construction conditions. The effort of this article aims to improve and develop the technique of design and construction in the coming projects having similar ground condition and supporting method.

• 한국과학교육학회지
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• 제29권8호
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• pp.874-885
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• 2009

본 연구의 목적은 달의 위상변화를 다룬 중학교 3학년 과학 교과서 6종의 삽화, 내용, 실험의 문제점을 분석하고, 달의 위상변화에 대한 교과서 삽화, 내용, 실험의 일관성 있는 새로운 구성을 제안하기 위함이다. 이를 위해 연구자는 '교과서 삽화가 달의 위상변화를 이해하는데 도움이 되는가?', '교과서 내용이 달의 위상변화를 이해하는 데 도움이 되는가?', '교과서 실험이 달의 위상변화를 이해하는데 도움이 되는가?', '교과서 삽화, 내용, 실험이 일관성 있게 달의 위상변화를 설명하고 있는가?'를 연구문제로 선정하였다. 연구자를 포함해 교육대학원생 10명이 본 연구에 참여하였으며, 연구 참여자 모두의 의견이 일치된 내용만을 연구결과에 반영하였다. 연구결과는 다음과 같다. 첫째, 달의 위상변화와 관련된 교과서 삽화에 우주관찰자 관점, 지구관찰자 관점이 혼재되어 나타나 있었다. 또한 일부 교과서 삽화에서는 '일출', '일몰' 등의 단어를 함께 제시하고 있어 너무 많은 내용을 하나의 삽화에 제시하고 있다. 둘째, 달의 위상변화와 관련된 교과서 내용이 불명확하게 진술되어 있었다. 특히 달의 위상변화 원인에 대한 명확하고 자세한 설명이 이루어지고 있지 않았다. 셋째, 한 교과서를 제외한 나머지 다섯 교과서에서 달의 위상변화와 관련된 실험을 지구관찰자 관점에서 다루고 있었지만, 지구관찰자에 대한 구체적인 언급을 하고 있지 않았다. 넷째, 교과서 삽화, 내용, 실험이 일관성 있게 달의 위상변화를 설명하고 있지 못했다.

• 한국해양공학회지
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• 제15권4호
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• pp.92-100
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• 2001

It is very important to determine the coefficient of earth pressure at rest accurately in order to estimate the behavior of soil structure. For estimation of K/sub 0/-value depending upon the stress history of dry sand, a new type of K/sub 0/-oedeometer apparatus is devised, and the horizontal earth pressure is accurately measured. For this study, 2 types of one-cyclic K/sub 0/-Loading/unloading models have been studied experimentally using four relative densities of the sand. The results obtained in this test are as follows : K/sub on'/ the coefficient of earth pressure at - rest for virgin loading is a function of the angle of internal friction Φ' of the sand and is determined as K/sub on/=1 - 0.914 sin Φ', K/sub ou'/ the coefficient of earth pressure at rest for virgin unloading is a function of K/sub on/ and over consolidation ratio(OCR), and is determined as K/sub ou/=K/sub on/(OCR)K/sup a/. The exponent α, increases as the relative density increases. K/sub or'/ the coefficient of earth pressure at rest for virgin reloading decreases in hyperbola type as the vertical stress, σ/sub v/’, increases. And, the stress path at virgin reloading leads to the maximum prestress point, independent upon the value of the minimum unloading stress. The gradient of this curve, m/sub r/ increases as OCR increases.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.950-958
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• 2017

Viaduct increases the height of subway catenary, namely magnifies lightning attraction scope that lead to higher possibility of suffering lightning stroke. Therefore, it is necessary to analyze performance of lightning striking to catenary of subway in viaduct section and propose an improving lightning protection scheme. In this paper, using ATP-EMTP simulation software to establish an associated model to evaluate lightning withstand level of catenary with existing lightning protection schemes including arrester and grounding point, an improving lightning protection scheme is proposed - every pillar ground earth and arresters are installed with some installing spacing between 200m to 400m based on lightning damage degree and reliability requirements - according to analyzing results: while lightning withstand level is lowest for lightning striking to the neutral pillar, lightning withstand level is greatest for lightning striking to the both-ends pillar that arrester and grounding point are both installed; grounding point could obviously improve lightning withstand level for lightning striking to ground wire while arrester could obviously improve the lightning withstand level for lightning striking to catenary; every pillar ground earth could enhance the lowest lightning withstanding level up to 2.5 times than of that pillar ground earth across every 200m.

• 한국농공학회논문집
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• 제64권4호
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• pp.1-10
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• 2022

A vegetative filter strip (VFS) is one of the best management practices (BMPs) to reduce pollutant loads. This study aims to assess the effectiveness of VFS in dense upland field areas. The study areas are agricultural fields in the Maedae (MD), Gaa (GA), and Jaun (JU) watersheds, where severe sediment yields have occurred and the Korean government has designated them as non-point management regions. The agricultural fields were divided into three or four clusters for each watershed based on their slope, slope length, and area (e.g., MD1, MD2). To assess the sediment trapping (STE) and pesticide reduction efficiency (PRE) of VFS, the Vegetative Filter Strip Modeling System (VFSMOD) was applied with three different scenarios (SC) (SC1: VFS with rye vegetation; SC2: VFS with rye vegetation and a gentle slope in VFS range; and SC3: VFS with grass mixture). For SC1, there were relatively short slope lengths and small areas in the MD1 and GA3 clusters, and they showed higher pollutant reduction (STE>50%, PRE>25%). For SC2 and SC3, all clusters in GA and some clusters (MD1 and MD3) in MD show higher pollutant reduction (>25%), while the uplands in JU still show a lower pollutant (<25%). With correlation analysis between geographic characteristics and VFS effectiveness slope and slope length showed relative higher correlations with the pollutant efficiency than a area. The results of this study implied that slope and slope length should be considered to find suitable upland conditions for VFS installations.

• Journal of Astronomy and Space Sciences
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• 제41권1호
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• pp.1-15
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• 2024

The Korean heliospheric community, led by the Korea Astronomy and Space Science Institute (KASI), is currently assessing the viability of deploying a spacecraft at the Sun-Earth Lagrange Point L4 in collaboration with National Aeronautics and Space Administration (NASA). The aim of this mission is to utilize a combination of remote sensing and in situ instruments for comprehensive observations, complementing the capabilities of the L1 and L5 observatories. The paper outlines longterm scientific objectives, underscoring the significance of multi-point in-situ observations to better understand critical heliospheric phenomena. These include coronal mass ejections, magnetic flux ropes, heliospheric current sheets, kinetic waves and instabilities, suprathermal electrons and solar energetic particle events, as well as remote detection of solar radiation phenomena. Furthermore, the mission's significance in advancing space weather prediction and space radiation exposure assessment models through the integration of L4 observations is discussed. This article is concluded with an emphasis on the potential of L4 observations to propel advancements in heliospheric science.

• 전기학회논문지
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• 제57권2호
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• pp.172-178
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• 2008

If the fault occurs on the underground power cable systems, the fault current on the sheath has an influence on all sections of cable because it's returned through earth at the directly grounded point and operation point of SVL(Sheath Voltage Limiter) on each insulated joint box. Therefore, the earth resistance and the operation of SVL have an effect on the zero-sequence current, and then the impedance between relaying point and fault point is increased. That causes the overreach of distance relay. For these reasons, the distance relay algorithm for protecting an underground power cable systems hasn't been developed till now. In this paper, new distance relay algorithm is developed for protecting a underground power cable system using fuzzy inference system which is the one of ACI(Advanced Computational Intelligence) techniques. This algorithm is verified by EMTP simulation of real power cable system, and proves to effectively advance the errors

• 한국지구과학회지
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• 제30권1호
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• pp.96-110
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• 2009

8학년(중학교 2학년)을 대상으로 '지구와 별' 단원의 지구계 수업 모듈을 개발하였다. 그리고 이 수업 모듈 중 태양계 행성을 학습하는 행성 리모델링 활동을 개발하였다. 이 활동의 핵심은 행성에 생명체가 살 수 있도록 행성을 리모델링하는 것이다. 본 연구에서는 쓰기와 그리기로 표현된 학생들의 생각의 시각화와 이를 통해 학생들의 이해를 해석하였다 학생들의 인지구조를 분석하기 위하여 4개로 법주화된 분석틀을 개발하여 적용하였다. 그리고 인지적 내용 특성을 분석하기 위하여 지구계의 구성 요소별 그리고 과학과 기술의 이용별로 분석 요소를 세분화하여 적용하였다. 행성 리모델링 활동을 통해 분석한 학생들의 인지에는 지구 소양과 같은 지구계 수업의 영향이 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.217-222
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• 1994

Generally speaking, grouting on the base stabilizes the ground as the aspects of mechanic and engineering properties, with drilling hole at any depth of the earth, and pressuring the cement milk or special chemical grouting material in it. The purpose of grouting on the base is waterproofness and solidification of the ground by earth concreting that the cement milk pass through paticles of soil or crack of rock. This report shows the fundamental properties of microcement compared with those of ordinary portland cement in a point of grouting. It also describes that experimental applications on the treatment of the weathered rock at the constructior of Taegu subway and Boryong earth filled dam site, south of chungchung province, resulted in success.