• Title/Summary/Keyword: foundation displacement

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The Development of Confocal Microscopy Using the Amplified Double-compound Flexure Guide (레버 증폭 구조의 플렉서를 이용한 공초점 현미경의 개발)

  • Lee, Sang-Won;Kim, Wi-Han;Jung, Young-Dae;Park, Min-Kyu;Kim, Jee-Hyun;Lee, Sang-In;Lee, Ho
    • Korean Journal of Optics and Photonics
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    • v.22 no.1
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    • pp.46-52
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    • 2011
  • A confocal microscope was developed utilizing a scanning sample stage based on a home-built double-compound flexure guide. A scanning sample stage with nano-scale resolution consisted of a double leaf spring based flexure, a displacement amplifying lever, a Piezo-electric Transducer(PZT) actuator and capacitance sensors. The performance of the two-axis stage was analyzed using a commercial finite element method program prior to the implementation. A single line laser was employed as the light source along with the Photo Multiplier Tube(PMT) that served as the detector. The performance of the developed confocal microscope was evaluated with a mouse ear skin imaging test. The designed scanning stage enabled us to build the confocal microscope without the two optical scanning mirror modules that are essential in the conventional laser scanning confocal microscope. The elimination of the scanning mirror modules makes the optical design of the confocal microscope simpler and more compact than the conventional system.

Pile and adjacent ground behaviors depending on horizontal offset between pile and tunnel subjected to horizontally loaded single pile (수평하중을 받는 단일 말뚝 하부 터널굴착 시 말뚝-터널 수평이격거리에 따른 말뚝 및 인접 지반 거동)

  • Ahn, Ho-Yeon;Oh, Dong-Wook;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.19 no.5
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    • pp.685-703
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    • 2017
  • Recently, as the number of high-rise building and earthquake occurrence are increasing, it is more important to consider horizontal load such as wind and seismic loads, earth pressure, for the pile foundation. Also, development of underground space in urban areas is more demanded to meet various problem induced by growing population. Many studies on pile subjected to horizontal load have been conducted by many researchers. However, research regarding interactive behavior on pile subjected to horizontal load with tunnel are rare, so far. In this study, therefore, study on the behaviors of ground and horizontal and vertical loads applied to single pile was carried out using laboratory model test and numerical analysis. The pile axial force and ground deformation were investigated according to offset between pile and tunnel (0.0D, 1.0D, 2.0D: D = tunnel diameter). At the same time, close range photogrammetry was used to measure displacement of underground due to tunnelling during laboratory model test. The results from numerical analysis were compared to that from laboratory model test.

Modelling and Analysis of Roll-Type Steel Mats for Rapid Stabilization of Permafrost (I) - Modeling - (영구동토 급속안정화를 위한 롤타입강재매트의 모델링과 해석(I) - 해석모델의 수립 -)

  • Moon, Do Young;Kang, Jae Mo;Lee, Janggeun;Lee, Sang Yoon;Zi, Goangseuo
    • Journal of the Korean Geosynthetics Society
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    • v.13 no.4
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    • pp.97-107
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    • 2014
  • Finite element modelling and analysis were conducted for the roll-type steel mats which were placed on loose sand and subjected to a standard truck wheel load in this study. The roll-type steel mats mean that the steel mats can be folded as a circle shape for the carrying to fields in cold regions where workability is limited and are developed for a rapid rehabilitation method for roadway across soft ground which is caused by thawing during the summer season in cold regions. The model is composed of link elements to simulate nonlinear behavior of connections between steel mats, thick shell elements to have flexural stiffness of the steel mats, and springs to simulate characteristics of foundation soils. The structural behaviors of the shell, link elements, and springs were verified at each modelling step through experiment and analysis. Beam and shell analysis without the link elements were conducted and compared to results obtained from the model presented in this study. Significant vertical displacement is shown in the shell model with hinge connections. Therefore, the results demonstrate that the analysis model for the roll-type steel mats on loose sand needs further detail parametric studies.

Verification of the Numerical Analysis on Caisson Quay Wall Behavior Under Seismic Loading Using Centrifuge Test (원심모형시험을 이용한 케이슨 안벽의 지진시 거동에 대한 수치해석 검증)

  • Lee, Jin-Sun;Park, Tae-Jung;Lee, Moon-Gyo;Kim, Dong-Soo
    • Journal of the Korean Geotechnical Society
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    • v.34 no.11
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    • pp.57-70
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    • 2018
  • In this study, verification of the nonlinear effective stress analysis is performed for introducing performance based earthquake resistance design of port and harbor structures. Seismic response of gravitational caisson quay wall in numerical analysis is compared directly with dynamic centrifuge test results in prototype scale. Inside of the rigid box, model of the gravitational quay wall is placed above the saturated sand layer which can show the increase of excess pore water pressure. The model represents caisson quay wall with a height of 10 m, width of 6 m under centrifugal acceleration of 60 g. The numerical model is made in the same dimension with the prototype scale of the test in two dimensional plane strain condition. Byrne's liquefaction model is adopted together with a nonlinear constitutive model. Interface element is used for sliding and tensional separation between quay wall and the adjacent soils. Verification results show good agreement for permanent displacement of the quay wall, horizontal acceleration at quay wall and soil layer, and excess pore water pressure increment beneath the quay wall foundation.

Evaluation Model for Lateral Flow on Soft Ground Using Commitee and Probabilistic Neural Network Theory (군집신경망과 확률신경망 이론을 이용한 연약지반의 측방유동 평가 모델)

  • Kim, Young-Sang;Joo, No-Ah;Lee, Jeong-Jae
    • Journal of the Korean Geotechnical Society
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    • v.23 no.7
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    • pp.65-76
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    • 2007
  • Recently, there have been many construction projects on soft ground with growth of industry and various construction problems concerning soft soil behavior also have been reported. Especially, foundation piles of abutments and (or) buildings which were constructed on the soft ground have been suffering from a lot of stability problems of inordinary displacement due to lateral flow of soft ground. Although many researches for this phenomena have been carried out, it is still difficult to assess the mechanism of lateral flow on soft ground quantitatively. And reliable design method for judgement of lateral flow occurrence is not established yet. In this study, PNN (probabilistic neural network) and CNN (committee neural network) theories were applied for judgment of lateral flow occurrence based on eat data compiled from Korea and Japan. Predictions of PNN and CNN models for new data which were not used during model development are compared with those predicted by conventional empirical methods. It was found that the developed PNN and CNN models can predict more precise and reliable judgment of lateral flow occurrence than conventional empirical methods.

Application of Probabilistic Neural Network (PNN) for Evaluating the Lateral Flow Occurrence on Soft Ground (연약지반의 측방유동 평가를 위한 확률신경망 이론의 적용)

  • Kim, Young Sang;Joo, No Ah;Lee, Jeong Jae;Lee, Sook Ju
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.1C
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    • pp.1-8
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    • 2008
  • Recently, there have been many construction projects on soft ground with growth of industry and economy. Therefore foundation piles of abutments and(or) buildings had been suffering from a lot of stability problems of inordinary displacement due to lateral flow of soft ground. Although many researches about lateral flow have been carried out, it is still difficult to assess the mechanism of lateral flow in soft ground quantitatively. And reasonable design method for judgement of lateral flow occurrence in soft ground is not established yet. In this study, six PNN (Probabilistic Neural Network) models were developed according to input variables and database compiled from Korea and Japan for the judgment of lateral flow occurrence. PNN models were compared with present empirical methods. It was found that the developed PNN models can give more precise and reliable judgment of lateral flow occurrence than empirical methods.

Full mouth rehabilitation with reorientation of occlusal plane using facial scan: a case report (교모 환자에서 안면 스캔을 활용하여 교합 평면을 재설정한 전악 보철 수복 증례)

  • Eun-Gyeong Kim;Sae-Eun Oh;Jee-Hwan Kim
    • The Journal of Korean Academy of Prosthodontics
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    • v.62 no.1
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    • pp.64-71
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    • 2024
  • The most critical aspect of full-arch prosthodontic treatment is evaluating whether the patient's vertical occlusal dimension is appropriate, and if necessary, restoring it through increasing vertical dimension. If the vertical occlusal dimension is too low, it can lead to reduced chewing efficiency, as well as not only aesthetic concerns but also potential issues like hyperactivity of muscles and posterior displacement of the mandible. This report is about the patient dissatisfied with pronunciation and aesthetics due to an inappropriate vertical occlusal dimension resulting from prior prosthetic interventions, underwent full-arch prosthodontic restoration treatment. Through the utilization of digital diagnostic apparatus, a comprehensive evaluation was undertaken for patient's vertical occlusal dimension, occlusal plane orientation, and the condition of prosthetic restorations. Through 3D facial scanning, the facial landmarks were discerned, and subsequently, the new occlusal plane was established. This provided the foundation for a digitally guided diagnostic wax-up. An elevation of 5 mm from the incisor was determined. Comprehensive dental rehabilitation was then executed for all remaining teeth, excluding the maxillary four incisors. The treatment protocol followed a systematic approach by initially creating implant-supported restorations on both sides of the dental arch to establish a stable occlusal contact. Subsequently, prosthetic restorations for the natural dentition were generated. Diagnostic and treatment planning were established through the utilization of facial scanning. This subsequently led to a reduction in treatment complexity and an expedited treatment timeline.

PRC Maritime Operational Capability and the Task for the ROK Military (중국군의 해양작전능력과 한국군의 과제)

  • Kim, Min-Seok
    • Strategy21
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    • s.33
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    • pp.65-112
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    • 2014
  • Recent trends show that the PRC has stepped aside its "army-centered approach" and placed greater emphasis on its Navy and Air Force for a wider range of operations, thereby reducing its ground force and harnessing its economic power and military technology into naval development. A quantitative growth of the PLA Navy itself is no surprise as this is not a recent phenomenon. Now is the time to pay closer attention to the level of PRC naval force's performance and the extent of its warfighting capacity in the maritime domain. It is also worth asking what China can do with its widening naval power foundation. In short, it is time to delve into several possible scenarios I which the PRC poses a real threat. With this in mind, in Section Two the paper seeks to observe the construction progress of PRC's naval power and its future prospects up to the year 2020, and categorize time frame according to its major force improvement trends. By analyzing qualitative improvements made over time, such as the scale of investment and the number of ships compared to increase in displacement (tonnage), this paper attempts to identify salient features in the construction of naval power. Chapter Three sets out performance evaluation on each type of PRC naval ships as well as capabilities of the Navy, Air Force, the Second Artillery (i.e., strategic missile forces) and satellites that could support maritime warfare. Finall, the concluding chapter estimates the PRC's maritime warfighting capability as anticipated in respective conflict scenarios, and considers its impact on the Korean Peninsula and proposes the directions ROK should steer in response. First of all, since the 1980s the PRC navy has undergone transitions as the focus of its military strategic outlook shifted from ground warfare to maritime warfare, and within 30 years of its effort to construct naval power while greatly reducing the size of its ground forces, the PRC has succeeded in building its naval power next to the U.S.'s in the world in terms of number, with acquisition of an aircraft carrier, Chinese-version of the Aegis, submarines and so on. The PRC also enjoys great potentials to qualitatively develop its forces such as indigenous aircraft carriers, next-generation strategic submarines, next-generation destroyers and so forth, which is possible because the PRC has accumulated its independent production capabilities in the process of its 30-year-long efforts. Secondly, one could argue that ROK still has its chances of coping with the PRC in naval power since, despite its continuous efforts, many estimate that the PRC naval force is roughly ten or more years behind that of superpowers such as the U.S., on areas including radar detection capability, EW capability, C4I and data-link systems, doctrines on force employment as well as tactics, and such gap cannot be easily overcome. The most probable scenarios involving the PRC in sea areas surrounding the Korean Peninsula are: first, upon the outbreak of war in the peninsula, the PRC may pursue military intervention through sea, thereby undermining efforts of the ROK-U.S. combined operations; second, ROK-PRC or PRC-Japan conflicts over maritime jurisdiction or ownership over the Senkaku/Diaoyu islands could inflict damage to ROK territorial sovereignty or economic gains. The PRC would likely attempt to resolve the conflict employing blitzkrieg tactics before U.S. forces arrive on the scene, while at the same time delaying and denying access of the incoming U.S. forces. If this proves unattainable, the PRC could take a course of action adopting "long-term attrition warfare," thus weakening its enemy's sustainability. All in all, thiss paper makes three proposals on how the ROK should respond. First, modern warfare as well as the emergent future warfare demonstrates that the center stage of battle is no longer the domestic territory, but rather further away into the sea and space. In this respect, the ROKN should take advantage of the distinct feature of battle space on the peninsula, which is surrounded by the seas, and obtain capabilities to intercept more than 50 percent of the enemy's ballistic missiles, including those of North Korea. In tandem with this capacity, employment of a large scale of UAV/F Carrier for Kill Chain operations should enhance effectiveness. This is because conditions are more favorable to defend from sea, on matters concerning accuracy rates against enemy targets, minimized threat of friendly damage, and cost effectiveness. Second, to maintain readiness for a North Korean crisis where timely deployment of US forces is not possible, the ROKN ought to obtain capabilities to hold the enemy attack at bay while deterring PRC naval intervention. It is also argued that ROKN should strengthen its power so as to protect national interests in the seas surrounding the peninsula without support from the USN, should ROK-PRC or ROK-Japan conflict arise concerning maritime jurisprudence. Third, the ROK should fortify infrastructures for independent construction of naval power and expand its R&D efforts, and for this purpose, the ROK should make the most of the advantages stemming from the ROK-U.S. alliance inducing active support from the United States. The rationale behind this argument is that while it is strategically effective to rely on alliance or jump on the bandwagon, the ultimate goal is always to acquire an independent response capability as much as possible.

Experimental study on the relaxation zone depending on the width and distance of the weak zone existing ahead of tunnel face (터널 굴진면 전방에 위치한 연약대 폭과 이격거리에 따른 이완영역에 대한 실험적 연구)

  • Ham, Hyeon Su;Lee, Sang Duk
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.20 no.5
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    • pp.855-867
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    • 2018
  • When a weak zone exists ahead of tunnel face, the stress in the adjacent area would increase due to the longitudinal arching effect and the stability of the tunnel is affected. Therefore, it is critical to prepare a countermeasure through the investigation of the frontal weakness zone of the excavated face. Although there are several researches to predict the existence of weak zone ahead of tunnel face, such as geophysical exploration, numerical analysis and tunnel support, lack of studies on the relaxation zone depending on the width or distance from the vulnerable area. In this study, the impact of the weak zone on the formation of the relaxation zone was investigated. For this purpose, a series of laboratory test were carried out varying the width of the weak zone and the separation distance between tunnel face and weak zone. In the model test, sand with a water content of 3.8% was used to form a model ground. The model weak zone was constructed with dry sand curtains. The tunnel face was adjusted to allow a sequential excavation of upper and lower half part. load cells were installed on the bottom of the foundation and the tunnel face and measuring instruments for displacement were installed on the surface of the model ground to measure the vertical stress and surface displacements due to tunnel excavation respectively. The test results show that the width of weak zone did not affect the ground settlement while the ground subsidence drastically increased within 0.25D. The vertical stress and horizontal stress increased from 0.5D or less. In addition, the longitudinal arching effect is likely within the 1.0D zone ahead of the tunnel face, which may reduce the vertical stress in the ground following tunneling direction.

Shear strain behaviour due to twin tunnelling adjacent to pile group (군말뚝 기초 하부 병렬터널 굴착 시 전단변형 거동 특성)

  • Subin Kim;Young-Seok Oh;Yong-Joo Lee
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.26 no.1
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    • pp.59-78
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    • 2024
  • In tunnel construction, the stability is evaluated by the settlement of adjacent structures and ground, but the shear strain of the ground is the main factor that determines the failure mechanism of the ground due to the tunnel excavation and the change of the operating load, and can be used to review the stability of the tunnel excavation and to calculate the reinforcement area. In this study, a twin tunnel excavation was simulated on a soft ground in an urban area through a laboratory model test to analyze the behavior of the twin tunnel excavation on the adjacent pile grouped foundation and adjacent ground. Both the displacement and the shear strain of ground were obtained using a close-range photogrammetry during laboratory model test. In addition, two-dimensional finite element numerical analysis was performed based on the model test. The results of a back-analysis showed that the maximum shear strain rate tends to decrease as the horizontal distance between the pillars of the twin tunnel and the vertical distance between the toe of the pile group and the crown of the tunnel were decreased. The impact of the second tunnel on the first tunnel and pile group was decreased as the horizontal distance between the pillars of the twin tunnel was increased. In addition, the vertical distance between the toe of the pile group and the crown of the tunnel had a relatively greater impact on the shear strain results than the horizontal distance of the pillars between the twin tunnels. According to the results of the close-range photogrammetry and numerical analysis, the settlement of adjacent pile group and adjacent ground was measured within the design criteria, but the shear strain of the ground was judged to be outside the range of small strain in all cases and required reinforcement.