• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.183-192
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• 2008

Generally, application of steel pipe pile as deep foundation member needs special requirement for the connection method between steel pipe pile and concrete footing. Even though two types of connection method are suggested in the korea highway bridge code, type-B method is prevalent. In this study, vertical, lateral, and tension loading test are done for two types of type B connection to review stress concentration, formation and behavior of imaginary RC column in the footing. Welding type and hook type as the connection method are considered in this study. Test results show that welding type have the more reserve capacity than hook type and the specimens connected by the welding type behave as the imaginary RC column in the footing. However, the specimens connected by the hook type did not behave as the imaginary RC column in the footing but behave as the hinge.

• Journal of the Korean Geotechnical Society
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• v.39 no.12
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• pp.93-102
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• 2023

Despite recent modifications to building structural standards emphasizing the seismic stability of building foundations, the current design focus remains solely on vertical support, resulting in insufficient consideration of horizontal loads during earthquakes. In this study, we evaluated the dynamic behavior of inclined tripod micropiles (ITMP), which provide additional seismic resistance against horizontal and vertical loads during earthquakes. A comparison of the dynamic characteristics, such as acceleration, displacement, bending moment, and axial force, of ITMP with a 15° installation angle and normal vertical micropiles with a 0° installation angle was performed using dynamic centrifuge model tests. Results show that under moderate seismic loads, the proposed ITMP exhibited lower acceleration responses than the vertical micropiles. However, when subjected to a long-period strong seismic excitation, such as sine (2 Hz), ITMP showed greater responses than the vertical micropiles in terms of acceleration and settlement. These results indicate that the use of ITMP reduces the amplif ication of short-period (high-f requency) contents compared with the use of vertical micropiles. Therefore, ITMP can be used to enhance seismic performance of structures.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.424_425
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• 2009

접지시스템은 인체의 안전을 확보함과 동시에 기기 및 장치의 확실한 동작과 절연 파괴를 방지하기 위한 가장 중요한 시스템이라 할 수 있다. 접지시스템은 전원설비용, 통신설비용, 피뢰설비용 접지로 크게 분류할 수 있으며 사고 발생 시 대지를 통하여 고장 전류를 신속하게 방전함으로서 기준전위를 유지하는 것을 목적으로 하며, 시스템 성능을 최적화하기 위하여 용도에 따라 서로 다른 목적의 접지라도 각 접지시스템을 본딩시켜 등전위를 형성하는 것이 가장 보편적으로 적용되는 설계 개념이다. 본 연구에서는 축소형 GIS 접지시스템의 계획과 시공에 있어서 좁은 지형조건에서 지반 보강용 철근 콘크리트 파일을 건축물 구조체 접지극으로 활용하여 mesh 접지망과 등전위화 함으로써 접지시스템의 효과를 증대 할 수 있는 방안을 제안하고 효과를 검증하고자 한다.

• Explosives and Blasting
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• v.33 no.2
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• pp.40-43
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• 2015

In this case study, a S/W optimized for ground vibration monitoring and analysis was developed. It was applied at vibrating compaction works for the ground improvement needed for the expansion of terminal 5 in Chagi International Airport in Singapore. The possible application of the new vibration analysis software to similar works like pile driving and the capability of long term and real time of the repeated wave vibration at seawalls, the vibration occurring from large structures like super tall buildings, tunnels, long cable hanging bridges, and etc were investigated.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.529-531
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• 2002

생방송 비디오 프록시는 사용자에게 최신의 비디오 데이터를 전송해야 한다. 그러나 큰 파일을 나누어 미리 캐싱하는 기존의 방법으로는 최신의 데이터를 보여줘야 하는 생방송 VOD의 제약을 만족시킬 수 없다. 본 논문에서는 생방송 비디오 스트림을 대상으로 효과적으로 캐싱할 수 있도록 클라이언트의 요청을 받는 큐와, 생방송 비디오 데이터를 저장하는 버퍼풀을 구성하였고, 이들이 제대로 동작하기 위한 동기화 과정을 설계하였다. 이 구조의 특징은 프록시가 클라이언트들의 요청을 일정시간 동안 모아서, 미디어 서버에게 한번만 요청한다는 데에 있다 미디어 서버는 프록시에게만 요청을 받고 데이터를 전달하게 되며, 모든 부하는 프록시 쪽으로 옮겨간다 결국 프록시 서버의 개수를 늘리거나 성능을 확장하면 서비스 가능한 클라이언트의 수를 확장시진 수 있는, 이른바 확장성의 개선을 기대할 수 있다. 실제로 구현해본 절과 지연시간 개선, 확장성 효과 등 프록시로서 만족할 만한 성능이 나옴을 확인하였다. 비연속적인 비디오 데이터를 대상으로 한 본 논문은, 오디오와 같이 연속적인 성질의 데이터에 대한 처리를 보강한다면 수요가 늘고있는 생방송 VOD서비스에 대비한 프록시 개발에 도움을 줄 것이다.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.845-862
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• 2009

Recently, Tunnel in soil has been designed frequently because Mountain Tunnel has been increased rapidly due to straight of horizontal curve and residents' complaints, tunnel portal has been planned at closed to surface for minimization of environmental damage. To excavate tunnel in soil, where displacement and crushing occur in tunnel face and crown because of unstable ground condition, appropriate reinforcement method needed. On this paper, through design and construction of the soil tunnel, consider application of reinforcement method, economical efficiency and stability.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1364-1368
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• 2006

By the countermeasure which is caused by with railroad station ground settlement it applied a CGS in each independent foundation. The effectiveness of the ground improvement and the bearing capacity of the compaction pile has been verified by the Cone Penetration Test(CPT) and Load Test. Test result show that penetration resistance and the cone friction force increased a lot and settlement 13.475mm as the standard settlement 40.0mm appeared at below. Also uniaxial compression test result $278kg/cm^2$ as the standard $150kg/cm^2$ appeared far a lot.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.247-248
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• 2020

본 논문은 동물 이미지 분류를 한 작은 데이터 세트를 기반으로 개선 된 딥 러닝 방법을 제안한다. 먼저, 소규모 데이터 세트에 대한 훈련 모델을 구축하기 위한 CNN이 사용되는 반면, 데이터 보강은 훈련 세트의 데이터 샘플을 확장하는 데 사용한다. 둘째, VGG16과 같은 대규모 데이터 세트에서 사전 훈련 된 네트워크를 사용하여 소규모 데이터 세트의 병목 현상 기능을 추출하여 두 개의 NumPy 파일에 새로운 학습 데이터 세트 및 테스트 데이터 세트로 저장한다. 마지막으로 새로운 데이터 세트로 완전히 연결된 네트워크를 학습한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.4
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• pp.70-77
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• 2010

Microcement grouting and micro pile are frequently used for ground modification during tunnel construction. The influence of grouting pressure of microcement grouting and micro pile to the existing bridge which is directly over the constructing tunnel is investigated. Three dimensional seepage flow-structure interactive analysis considering firm water pressure with full stages of construction including the construction of upper bridge, microcement grouting, micro pile and tunnel is performed. The settlement and tilting of the pier of existing bridge violate the design code and the reaction of the bridge are highly increased after grouting. The stress of tunnel bracings such as rockbolt and shotcrete also exceed the limit of the code. The pressure of microcement grouting is confined by bedrock and transmit to the surrounded soil and the upper bridge. Microcement grouting needs mid-high pressure to penetrate through weak fault plane and the pressure greatly influence the safety of the upper structure. It is important to decide and care the grouting pressure to improve weak fault plane directly under the existing structures and the pressure of microcement grouting should be considered in underground analysis.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.3
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• pp.543-560
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• 2018

With the increased development in downtown underground space facilities that vertically cross under a railway at a shallow depth, the demand for non-open cut method is increasing. However, most construction sites still adopt the pipe roof method, where medium and large diameter steel pipes are pressed in to form a roof, enabling excavation of the inside space. Among the many factors that influence the loosening region and loads that occur while pressing in steel pipes, the size of the pipe has the largest impact, and this factor may correspond to the magnitude of load applied to the underground structure inside the steel pipe roof. The super equilibrium method (SEM) has been developed to minimize ground disturbance and loosening load, and uses small diameter pipes of approximately 114 mm instead of conventional medium and large diameter pipes. This small diameter steel pipe is called an SEM pile. After SEM piles are pressed in and the grouting reinforcement is constructed, a crossing structure is pressed in by using a hydraulic jack without ground subsidence or heaving. The SEM pile, which plays the role of timbering, is a fore-poling pile of approximately 5 m length that prevents ground collapse and supports surface load during excavation of toe part. The loosening region should be adequately calculated to estimate the spacing and construction length of the piles and stiffness of members. In this paper, we conducted a comparative analysis of calculations of loosening load that occurs during the press-in of SEM pile to obtain an optimal design of SEM. We analyzed the influence of factors in main theoretical and empirical formulas applied for calculating loosening regions, and carried out FEM analysis to see an appropriate loosening load to the SEM pile. In order to estimate the soil loosening caused by actual SEM-pile indentation and excavation, a steel pipe indentation reduction model test was conducted. Soil subsidence and soil loosening were investigated quantitatively according to soil/steel pipe (H/D).