• 한국지반환경공학회 논문집
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• 제4권4호
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• pp.17-23
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• 2003

플라스틱보드드레인(PBD)공법에 의해 개량된 연약점토지반의 압밀특성은 아직 충분히 밝혀져 있지 않기 때문에 개량지반의 압밀거동을 정확히 예측하기는 어려운 실정이다. PBD공법에 사용되는 배수재의 형상은 개량지반의 압밀특성에 영향을 미치는 중요한 인자중의 하나로 알려져 있다. 본 연구에서는PBD공법에 의해 개량된 연약지반의 압밀특성에 미치는 배수재의 폭과 재하중 상태의 영향을 고찰하기 위하여 일련의 실내모형실험을 실시하였다. 모형실험의 결과로부터 모형지반의 침하 및 과잉간극수압의 소산거동과, 모형지반내의 함수비 분포형상을 파악할 수 있었다. 그리고 모형실험결과에 미친 모형지반 상부의 배수조건의 영향을 검토하기 위해서 Barron의 이론해에 의한 압밀거동과 비교, 고찰하였다. 그 결과 모형실험에 의한 압밀거동은 방사방향의 배수조건 뿐만 아니라 연직방향 배수조건으로부터도 영향을 받았음을 알 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1724-1729
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• 2003

A new ground transportation system is often simulated by the wing in ground effect(WIG). Recently, several kinds of experimental and computational studies are being carried out to investigate the WIG aerodynamic characteristics which are of practical importance to develop the new ground transportation vehicle system. These works are mainly based on conventional wind tunnel tests, but many problems associated with the WIG aerodynamic characteristics can not be satisfactorily resolved. In order to develop the new ground transportation vehicle system the WIG should be further investigated. To do this, it is necessary to develop a s imulator appropriate to the WIG aerodynamics. The objective of the present study is to clarify the aerodynamic characteristics of the WIG and to develop a new experimental test rig for the investigation of the WIG aerodynamics. Some preliminary experiments are performed to investigate the usefulness of the WIG simulator.

• 한국지반환경공학회 논문집
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• 제1권1호
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• pp.27-33
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• 2000

쇄석말뚝 공법은 다져진 자갈, 폐석, 쇄석 등을 이용하여 느슨한 사질지반이나 연약점성토 지반을 개량하는 공법으로 일반적으로 말뚝은 70%이상의 치환율로 실트질 점토에 시공되어 지지력을 증진시키는 공법이나 말뚝을 배수층으로 압밀에 의한 점성토의 지반의 강도 증가를 전제로 치환율을 30% 이하로 억제하는 저치환 공법의 효율에 관한 연구가 진행되고 있다. 본 연구에서는 쇄석말뚝의 치환율에 따른 단일 등가원주 모형 실험을 실시하여 쇄석말뚝이 연약지반의 압밀거동에 미치는 영향을 분석하였다. 실험결과 치환율의 증가에 따른 침하감소효과와 침하저감계수를 산정하였으며 복합지반의 압밀시간 단축을 확인하였다. 또한, 복합지반에 대한 이론식을 이용한 장기침하량 예측을 통해 보강지반의 침하억제 경향을 평가하고 베인전단시험을 통해 복합지반의 강도증가특성을 확인하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.303-314
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• 2010

This study, as basic research which was intended to develope the surface reinforcement method using reinforcement material which is applicable to very soft ground in Korea, was aimed at proposing the design parameter for the surface ground improvement method. To that end, a wide width tensile test using geotextile, geogrid and steel bar (substitute for bamboo) and 49 kinds of the laboratory model tests were conducted. And the result the study suggested $\beta_s$, the stiffness coefficient to evaluate the stiffness effect of reinforcement materials. Then, it was also found that the stiffness coefficient, $\beta_s$ as the testing constant would be appropriate as high as 1.0, 1.1 and 1.5 for geotextile, geogrid and steel bar, respectively. And It was evaluated that the stiffness effect affecting reinforcement improvement effect would be reduced as the thickness of embeded depth increases and that RFe, the stiffness effect reduction coefficient would have positive correlation with H/B. Finally, it was confirmed that the bearing capacity gained from the method to calculate bearing capacity, which was suggested in the study, would almost correctly estimate the capacity, demonstrating the appropriateness of the proposed bearing capacity calculation method.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.480-488
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• 2010

The CGS method is non-discharge replacement method improving ground stiffness by the effect of static compaction with injecting very low slump mortar into ground, and is applied for increasing bearing capacity and filling ground cavity by lifting or restoring differential settled structures and preventing differential settlement. This paper suggests design of ground improvement and construction case history for civil engineering structures by CGS method. This method can be used for reinforcing soft ground and liquefaction of loose sandy soil. This method was used in SongDo area in Incheon Economic Free Zone due to its low vibration of ground while it can improve the soft soil where underground structures(subway and box culvert) are already existed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.605-610
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• 2000

A series of wind tunnel test were conducted on Korean high speed train model to understand the flow physics around the vehicle related to the aerodynamic drag. For the wind tunnel test on high-speed ground vehicle, a moving ground simulation is necessary to predict the aerodynamic drag accurately. So, the models were tested in three wind tunnels with various ground simulation facility including moving belt ground plane system and tangential blowing system. The test results including measured aerodynamic drag and flow visualization showed that a tangential blowing method can be an alternative ground simulation method in short time using conventional wind tunnel.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.100-107
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• 2001

One major problem in the model testing is the boundary effect and size effect caused by the limit in the size of the container. To overcome this problem, various types of laminar boxes are gradually manufactured and used in the shaking table test, which ideally has zero stiffness to horizontal shear. In this study, a small-scale laminar box is manufactured, which is composed of 6 thin aluminum rectangular hollow plates, and its inside dimensions are 300 mm length by 200 mm width by 350 mm depth. Shaking table tests are performed both with the laminar box and the rigid box under the same conditions, where displacements and accelerations are measured at various points of the box and model ground. As result of analyzing the measured data, during the propagation of input seismic motion from the bottom to the ground surface, the relative displacement of the model ground and the amplification of acceleration is hardly amplified in the rigid box. Because of the effect of stress waves reflecting from the rigid wall, the acceleration is slightly decreased at the edge in the rigid box. The laminar box, manufactured in this study, has a problem in that the soil behavior at the edge of ground surface is affected by the inertia force of the top layer due to its excessive self-weight.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.437-442
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• 2005

The high pressure jet grouting method is mainly used in the grouting. But, this method has problems that the scale and strength of improved body is not constant with ground condition. Considering these problems, triple rod MJM that results in the high-strength effect by the technology of the injected ${\phi}7mm$ cement mortar was developed. In this MJM, the unconfined strength is estimated with the various combination ratio and engineering characteristic, strength improvement effect of improved body, was checked through the field test. It is known that the application of MJM was verified with ground and construction condition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.464-465
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• 2008

Concrete poles(CP) are popular supports for distribution lines. Various types of grounding electrode, such as copper-clad rods, have been used to maintain CP's ground resistance under the required value. The buried part of CP can also have structural grounding effect because of its iron reinforcing rods inside CPs. In this paper, we measured the total ground current injected into CP ground while measuring the ground current splitting to the metal electrode as well as the total injecting current. By this, it was able to measure the ground current splitting to CP structure. Based on the measured results, interrelationship between ground resistance of metal electrodes and current split factor to CP structure was analyzed.

• 전기학회논문지
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• 제57권7호
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• pp.1223-1228
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• 2008

While a high frequency source is used for measuring the ground impedance, there are several factors having an effect on the measured value. A primary factor of the measurement error is the ac mutual coupling between current and potential test leads. The mutual coupling causes the test current to induce a voltage into the potential test lead that adds to the actual ground potential rise and produces a significant measurement error as the length of the test leads paralleled is prolonged. In order to avoid the mutual coupling, it is recommended that the ground impedance be measured by angled arrangement of test leads. The mutual impedance due to the inductive coupling with an angle of $90^{\circ}$ was calculated at $0^{\circ}$ by Campbell/Foster Method. With an angle of $180^{\circ}$, the mutual impedance was calculated large value enough to introduce a fairly large margin of error, however, the measured value of ground impedance was close to the value at $90^{\circ}$.