• 조명전기설비학회논문지
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• 제19권2호
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• pp.63-68
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• 2005

본 논문은 메쉬 접지전극이나 침부 매설지선이 연결된 심매설 봉상 접지전극의 실효임펄스접지임피던스의 특성을 다루었다. 시험용 접지전극의 전위상승은 인가된 임펄스 전류의 상승시간의 함수로 측정되었고, 실효임펄스접지 임피던스는 산출되었다. 심매설 봉상 접지전극의 임펄스접지임피던스는 임펄스 전류의 상승시간에 강하게 의존하며 메쉬 접지전각과의 병렬연결에 의해 확연히 감소하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.672-679
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• 2008

During recent years, the large soft ground improvements very rapidly increase with industrial development and it is the types and scales of structure that is enlarged by degree. Then, we must enter construct equipment to improve soft ground and we fulfilled works by carrying out soft clay soil to gain trafficability for them. For improving the soft ground, we lay geotextile on soft clay ground and fill the filter sand that can drain the pore water. Then, we landfill cover soil for come by trafficability of construction tools. Ater that we penetrate vertical drain for dehydration through soft ground. there are very complicated works. For these reason we suggest the methods of soft ground improvement constructions.

• 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.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.3-11
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• 1998

Response of tall buildings to near-field ground motions with distinct low-frequency pulses can differ dramatically from, for example, the response to the 1940 El Centro ground motion. For the same peak ground acceleration (PGA) and duration of shaking, ground motions with a pulse-like characteristic can generate much higher base shear, inter-story drifts and roof displacement in a high-rise building as compared to ground motions without the characteristic pulse. Also, the ductility demand is much higher and the effectiveness of supplemental damping is lower for pulse-like ground motions. This paper presents a simple interpretation of the response characteristics for two recorded and one synthetic near-field pulse-like ground motions.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.347-354
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• 2002

In this paper, when structures are constructed in the soft ground with poor bearing capacity at Incheon International Airport(railroad area), as for the grouting columns built In soft ground by high pressure jet grouting with Triple tube rod(super injection grouting), the effects on reinforcement and bearing capacity of ground are investigated. A unconfined compressive strength tests has been performed on the specimens sampled from the grouting columns and a mass plate bearing test has been performed on a grouting column. The test results show that super injection grouting has a sufficient effect on composite ground improved of foundation ground and reatraint of settlement of structure.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.611-618
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• 2002

In this study the CGS as an injection method by low slump mortar was performed the pilot test to confirm the applicability of this method and the effectiveness of settlement restraint. From the results, there has been concluded the construction control standard such as an institutional diameter, space, depth, injection materials, Infection pressure etc. Also, there has been estimated the ground improvement effectiveness which has resulted from the field investigation and consolidation test etc. From the results, in the adjacent ground the CGS, generally, has been confirmed to in-crease ground strength to improve the consolidation characteristic obtained from the field investigation and consolidation test. Especially, the CGS which performed the larger stiffness to the ground has been concluded that the settlement restraint to the ground complicates the ground effect which Increases the bearing capacity and stress assignment. So, the CGS can be considered as an effective method to increase the bearing capacity as well as the settlement restraint of soft ground.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1849-1851
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• 2003

To obtain a low ground resistance in high resistivity soil, long vertical ground rods are often used. However, if the lightning current or fault current with high frequency flow into the grounding system, the ground impedance is significantly increased because of the inductive behavior. This paper presents how the impulse current works on the long vertical ground electrodes. The different shape of current was impressed between ground rods and auxiliary electrode by using impulse generator and the ground impedance was calculated from the ground potential rise.

• Earthquakes and Structures
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• 제10권3호
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• pp.563-588
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• 2016

In this study, solution models are proposed to obtain code-compatible ground motion record sets which can be used for both uni-directional and bi-directional dynamic analyses. Besides scaled, unscaled ground motion record sets are obtained to show the utility and efficiency of the solution models. For scaled ground motion sets the proposed model is based on hybrid HS-Solver which integrates heuristic harmony search (HS) algorithm with the spreadsheet Solver add-in. For unscaled ground motion sets HS based solution model is proposed. Design spectra defined in Eurocode-8 for different soil types are selected as target spectra. The European Strong Motion Database is used to get ground motion record sets. Also, a sensitivity analysis is conducted to evaluate the effect of different HS solution parameters on the solution accuracy. Results show that the proposed solution models can be regarded as efficient ways to develop scaled and unscaled ground motion sets compatible with code-based design spectra.

• 한국지반공학회논문집
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• 제31권11호
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• pp.41-48
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• 2015

대규모 지반침하 및 지반함몰로 인한 재산, 인명피해를 사전에 예방하기 위하여 지반의 공동 및 이완구간에 대한 조사는 필수적이다. 최근, 지하투과레이더를 이용한 지반침하 및 지반함몰 구간 예측과 관련된 연구가 활발히 진행되고 있으나, 기존의 지하투과레이더 탐사에서는 전기적 임피던스가 서로 다른 층간 경계면 심도만을 산정하므로 조밀한 지반과 느슨한 지반을 서로 반대로 예측하는 오류를 범할 수 있었다. 본 연구에서는, 지하투과레이더로부터 획득된 전자기파의 반사파 특성을 이용하여 이완구간 심도를 추정하고자 하였다. 이완구간에 따른 신호획득을 위하여 과거 침하이력이 있었던 현장을 대상으로 지하투과레이더 탐사가 수행되었으며, 결과의 상호비교 및 검증을 위하여 동적 콘 관입시험이 수행되었다. 전자기파의 반사특성 분석 결과, 지하투과레이더 안테나에서 처음 측정된 신호와 조밀한 지반에서 반사되어 측정된 전자기파는 동일한 위상을 보이며, 느슨한 지반에서 반사되는 경우 안테나에서 처음 측정된 신호와 반대 위상을 보이는 것으로 나타났다. 획득된 지하투과레이더 신호로부터 대상지반의 이완구간 심도 산정 및 동적 콘 관입지수와 상호비교 결과, 지하투과레이더 신호 분석으로부터 산정된 이완구간 또는 조밀한 구간의 심도는 높은 신뢰도로 산정되었다. 본 연구에서 수행된 지하투과레이더 신호획득 및 분석과정은 지반 불연속층의 심도산정뿐만 아니라 이완구간 산정에 활용될 수 있을 것으로 판단된다.

• 한국지반공학회논문집
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• 제32권11호
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• pp.83-96
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• 2016

흙막이 벽체 배후지반의 지표 침하는 인접구조물의 안전성에 많은 영향을 미친다. 그러나 지반굴착에 따른 주변 지반의 침하는 예측하기가 쉽지 않고 굴착면으로부터 이격거리에 따른 침하량을 정량적으로 구하는 것은 더욱 어려운 일이다. 흙막이 벽체의 변형에 의한 지표침하는 수치해석(FEM)이나, 경험적 방법 Peck(1969)등으로 추정하고 있으나 주로 토사층을 대상으로 하고 있다. 본 연구에서는 토사층 하부에 암반층이 위치하는 복합지반을 굴착 할 때 암반층의 깊이와 절리경사에 따른 흙막이 벽체 배후지반의 지표침하를 대형모형실험(규격: $3m{\times}3m{\times}0.5m$)을 수행하여 측정하였다. 모형실험은 축척 1/14.5로 하고 10단계로 굴착을 하였다. 암반층 비율은 35%와 50%로 하였고 암반층의 절리경사를 $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$로 하여 단계굴착하면서 흙막이 벽체 버팀대에 작용하는 토압(Lee 2014)과 흙막이 벽체 배후지반의 지표 침하량을 측정하였다. 암반층비율과 암반층 절리경사가 증가하면 배후지반의 지표침하량도 증가하며 암반층 절리경사 $60^{\circ}$(J60)에서는 수평지반 굴착시에 비해 최대 17배 크게 발생하였다. 흙막이벽체 배후지반에서 최대 지표침하는 경험적 방법과 달리 흙막이 벽체로부터 굴착깊이의 17%~33%만큼 이격된 위치에서 가장 크게 발생하였다. 복합지반의 지표침하는 전반적으로 경험적 추정방법에 의한 지표침하량에 비해 작게 나타났다.