• Journal of electromagnetic engineering and science
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• 제12권4호
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• pp.247-253
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• 2012

This study presents a new, simple method for improving the front-to-back (F/B) ratio of a microstrip patch antenna. The back radiation of the microstrip patch antenna is reduced by removing some metallic parts around the ground plane and placing a new soft-surface configuration, consisting of an array of stand-up split-ring resonators on a bare dielectric substrate near the two ground plane edges. Compared to the F/B ratio of a conventional microstrip patch antenna with a full ground plane of the same size, our proposed microstrip patch antenna experimentally achieves an improved F/B ratio of 9.6 dB.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.398-403
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• 2002

The low slump mortar grouting is widely used in reinforcement of structural foundation and ground improvement in soft ground. It also has merit that construction is possible in insufficient space. In this study, the main purpose is to evaluate effects for contiguous structures that can be happened along with soft ground improvement by the low slump mortar grouting. To estimate these effects, numerical analysis using finite difference method was applied. It was performed to analyze settlement, upheaval and horizontal displacement of surrounding ground and to measure horizontal stress variation by the first and the second grouting in the pile foundation.

• 한국지반공학회논문집
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• 제19권6호
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• pp.307-323
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• 2003

본 연구에서는 침하가 발생한 연약지반에 대하여 저유동성 몰탈에 의한 주입공법인 C.G.S공법의 적용성과 침하억제 효과를 확인하기 위하여 시험시공을 실시하였으며, 그 결과를 이용하여 지반조건에 적합한 설치직경, 간격, 심도, 주입재, 주입압 등 다양한 조건을 고려한 시공관리기준을 정하여 본 시공을 실시하였다. 본 시공과정 중에는 지반개량 효과를 파악하기 위하여 C.G.S개량 전, 후 현장지반조사 및 이에 따른 실내토질시험, 계측관리 등을 수행하였다. 현장 조사시험에 의한 강도특성 확인결과 C.G.S주입 주변지반은 개량전과 비교하여 전반적으로 지반강도가 증가되었음을 확인할 수 있었다. 또한, 계측관리 및 압밀특성을 분석한 결과 주변지반의 압밀특성이 개선되었음을 확인할 수 있었으며, 특히 C.G.S주입재의 압축강도시험 결과 주변지반에 비해 강성이 매우 큰 C.G.S주입에 따른 복합지반효과를 통해 지지력 증대효과 및 응력분담으로 장래침하량을 억제할 수 있는 것으로 나타났다. 이와 같이 연약점성토 지반에서 C.G.S주입시공에 의한 침하억제효과로부터 공법의 적용성이 매우 양호한 것을 확인할 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.1042-1050
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• 2008

In this study, SCP method was used by purpose to improve loose sand and soft clay that is drilled Sand Compaction Pile in underground. Settlement behavior of field analyzed through SCP method. When sand Compaction Pile drilled in clay, forming composite ground that foundation and Sand Compaction Pile behavior. According to SCP method can expect bearing capacity improvement, Settlement reduction, lateral flow protection. SCP increase the consolidation settlement of ground and it reduce settlement for that purpose increase liquefaction resistance, lateral Resistance. Because SCP had been widely used for sand. Area of Inchon-A by sand compose clay and silt to upper Ground and compose soft clay to under ground. After pre-loading, it measured settlement by extensometer and settlement extensometer that purpose of ground improvement with 13% in replacement ratio. The result analyzed settlement behavior is similar to Multi-layered Ground that it happened to elastic settlement at upper ground and to consolidation settlement at under ground.

• 한국지반환경공학회 논문집
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• 제20권2호
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• pp.19-28
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• 2019

국내 서해안 지역은 대부분 퇴적된 연약점성토로 이루어져 있으며, 구조물을 시공하기 전에 현장에 적합한 지반개량 공법의 적용이 필요하다. 본 연구에서는 CGS(Compaction Grouting System) 공법의 적용성을 파악하기 위하여 매립토 및 연약점성토로 이루어진 인천국제공항시설 현장에 공법을 적용하였다. CGS 공법은 현장 성토부의 지반개량 효과를 얻기 위함뿐만 아니라 교대의 말뚝기초 역할을 위해 적용되었으며, 본 공법의 지반개량 효과를 파악하기 위하여 공법 적용 전 후 지반의 개량 효과를 콘 관입시험을 수행함으로써 비교 분석하였다. CGS 공법의 적용 결과 현장지반의 전반적인 강도 증대 효과를 얻을 수 있었으며, 이는 현장교대의 하중을 충분히 견딜 수 있는 것으로 파악되어 말뚝기초로의 역할과 지반개량공법으로써의 CGS 공법의 적용성을 검증하였다. 또한 공동팽창이론을 적용하여 상부 구근의 크기 예측을 수행하였으며, 시공 후 상부구근 육안 확인을 통하여 시공 후 구근예측에 있어 공동팽창이론의 적용 가능성을 평가하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.918-927
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• 2008

The problems associated with constructing high-speed concrete track embankments over soft compressible soil has lead to the development and/or extensive use of many of the ground improvement techniques used today. Drains, surcharge loading, and geosynthetic reinforcement, have all been used to solve the settlement and embankment stability issues associated with construction on soft soils. Geosynthetic-reinforced embankment supporting piles method consist of vertical columns that are designed to transfer the load of the embankment through the soft compressible soil layer to a firm foundation and one or more layers of geosynthetic reinforcement placed between the top of the columns and the bottom of the embankment. In the paper, the evaluations of a seismic performance of geosynthetic-reinforced embankment piles for a ultra soft ground during earthquake were studied. the equivalent linear analysis was performed by SHAKE for soft ground. A seismic performance analysis of Piles was performed by GROUP PILE and PLAXIS for geosynthetic-reinforced embankment piles. Guidelines is required for pile displacement during earthquake. Conclusions of the studies come up with a idea for soil stiffness, conditions of pile cap, pile length and span.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.336-345
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• 2010

GS E&C was awarded the contract for the construction of Hanoi - Hai Phong Expressway Package EX-7 from Station Km 72+000 to Station Km 81+300 in December 2008. This project is the $7^{th}$ contract package of the 105.5 km long expressway near Hai Phong city, which includes a FCM-styled bridge along with high embankments over soft ground. For these high embankments, there is a need to treat the soft soil for improving the overall stability during construction and for reducing the post-construction settlement of the expressway. The Designer of this project had adopted four (4) different types of ground improvement techniques to treat the soft ground, including the prefabricated vertical drains (PVD), sand drains (SD), pack drains (PD, or sometimes called packed sand drains), and sand compaction piles (SCP). The main focus of soft soil treatment should be paid attention to the residual settlement after construction. In current design, however, it appeared that the secondary compression (or creep) of the improved soil layer and the consolidation settlement of the lower untreated compressible soil layer have been neglected in the estimation of the post-construction settlement. These uncalculated residual settlements may not only unsatisfy the design criteria but also raise serious problems during service period of this expressway. In this paper, the subsoil condition and current design were reviewed focusing on the employed soft soil treatment method and expected residual settlement.

• 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.

• 한국지반환경공학회 논문집
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• 제15권3호
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• pp.5-13
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• 2014

본 논문에서는 준설토를 활용한 경량혼합토(LWFS)의 연약지반개량 적용성에 대해 검토한 내용을 다루었다. 현재까지 제시된 경량혼합토의 공학적 특성에 관한 연구결과를 종합 분석하여 경량혼합토의 물성을 정리하였으며, 그 결과를 토대로 임의의 현장조건을 가정하여 경량혼합토공법과 SCP 공법 및 DCM 공법 적용 시에 대한 3차원 수치해석을 수행하였다. 연약지반개량공법 비교해석 결과, 경량혼합토 공법을 적용하는 경우 SCP 공법을 적용하는 수준 이상의 침하관리가 가능하며, 경량혼합토의 목표성능에 따라 침하발생 수준을 조절할 수 있는 것으로 검토되었다. 또한 DCM 공법과 비교 시 경량혼합토 재료의 경량성으로 과잉간극수압 발생량이 현저히 작아져 잔류침하를 최소화할 수 있는 것으로 검토되었다.

• 산업기술연구
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• 제25권A호
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• pp.67-73
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• 2005

In this research, centrifuge model experiments and numerical approach of finite element method to analyze experimental results were performed to investigate the behavior of improved ground with sand compaction piles. One of typical clay minerals, kaolinite powder, were prepared for soft ground in model tests. Jumunjin standard sand was used to sand compaction pile installed in the soft soil. In order to investigate the characteristics of mechanical behavior of sand compaction piles with low replacement ratios, centrifuge model experiments with the replacement ratio of 40%, changing the width of improved area with respect to testing results the width of surcharge loads, were carried out to obtain of bearing capacity, characteristics of load-settlement, vertical stresses acting on the sand pile and the soft soil failure mechanism in improved ground.