• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.15-20
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• 2011

This study presents the behavior characteristics of buried three-layered pipeline subjected to pile driving loads corresponding to its cover depth. The analysis considered the driving energy caused by 7 tonf of ram weight and 1.2m of stroke with 20m distance from buried pipeline for all the analysis cases. A cover depth of pipe is varied 0.6m to 3.8m for this research. Vibration Velocity and stress are investigated at the center section in longitudinal direction. With same distance from pile, attenuation ratio of vibration velocity for increment of cover depth has shown an increasing trend. Also, Stress attenuation ratio of inner pipe is increased with cover depth.

• Korean Journal of Construction Engineering and Management
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• v.17 no.4
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• pp.87-94
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• 2016

The necessity to consider stability of underground structures constructed below or adjacent ammunition depots has been increased since the expansion of urban area and construction of infrastructure. However, there are a few studies on influence of accidental explosion on underground structures. In this study, the process of assessing the stability of underground structures is suggested and its applicability is verified through the case study. AUTODYN and SPACECLAIM are used to execute the structure and geotechnical modelling, and explosion effect is simulated and vibration velocities are calculated. According to the result of this case study, it is concluded that underground structure constructed 70m below ground might be rarely influenced by the simulated explosion. The process used in this study could be used to design the underground ammunition complex and analyse the stability of underground facilities being influenced by periodical vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1253-1258
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• 2007

The media transport systems, such as printers, copy machines, facsimiles, ATMs, cameras, etc. have been widely used and being developed rapidly. In the development of those sheet-handling machineries, it is important to predict the static and dynamic behavior of the sheet with a high degree of reliability because the sheets are fed and stacked at such a high speed. Flexible media are very thin, light and flexible, so they behave in geometric nonlinearity with large displacement and large rotation but small strain. In the flexible media analysis, aerodynamic effect from the surrounding air must be included because any small force can make large deformation. In this paper, only the flexible media analysis is performed as early stage of analysis including aerodynamic effect. Through formulations and simulations for total Lagrangian(TL), updated Lagrangian (UL) and co-rotational(CR) method which are widely used for geometric nonlinear analysis, usefulness and reliability of each methods are investigated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1335-1340
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• 2007

The media transport systems, such as printers, copy machines, facsimiles, ATMs, cameras, etc. have been widely used and being developed rapidly. In the development of those sheet-handling machineries, it is important to predict the static and dynamic behavior of the sheet with a high degree of reliability because the sheets are fed and stacked at such a high speed. Flexible media are very thin, light and flexible, so they behave in geometric nonlinearity with large displacement and large rotation but small strain. In the flexible media analysis, aerodynamic effect from the surrounding air must be included because any small force can make large deformation. In this paper, surrounding air was modeled by incompressible Navier-Stokes flow and an arbitrary Lagranigan-Eulerian(ALE) finite element method with automatic mesh-updating technique was formulated for large domain changes. In the numerical simulations, the results with consideration of the air fast decayed and converged into static results while the results without considering air oscillated continuously.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.247-250
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• 2007

Flexible media such as the paper, the film, etc. are thin, light and very flexible. They behave in geometrically nonlinear. Any of small force makes large deformation. So we must including aerodynamic effect when its behavior is predicted. Thus, it becomes fully coupled fluid-structure interaction(FSI) problem. In FSI problems, where the fluid mesh near the structure undergoes large deformations and becomes unacceptably distorted, which drive the time step to a very small value for explicit calculations, the arbitrary Lagrangian-Eulerian(ALE) methods or rezoning are used to create a new undistorted mesh for the fluid domain, which allows the calculations to continue. In this paper, FE sheet model considering geometric nonlinearity is formulated to simulate the behavior of the flexible media. Aerodynamic force to the media by surrounding air is calculated by solving the incompressible Navier-Stokes equations. Q2Q1(Taylor-Hood) element which means biquadratic for velocity and bilinear for pressure is used for fluid domain. Q2Q1 element satisfies LBB condition and any stabilization technique is not needed. In this paper, cantilevered sheet in the viscous incompressible Navier-Stokes flow is simulated to check the mesh motion and numerical integration scheme, and then falling paper in the air is simulated and the effects of some representative parameters are investigated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.2 s.95
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• pp.206-212
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• 2005

In many machines handling lightweight and flexible media, such as magnetic tape drives, xerographic copiers and sewing machines, the media must transit an open space. It is important to predict the static and dynamic behavior of the sheets with a high degree of reliability. The nonlinear theory of the dynamic elastica has often been used to a nonlinear dynamic deflection model. In this paper, the governing equation is derived and simulated by the finite difference method. The parametric cubic curve is applied for defining the guide shape. The dynamic contact conditions suggested by Klarbring is used to predict the direction of the flexible media according to the initial velocity and the friction coefficient. The analysis is also compared to the conventional model, showing that after contacting a $45^{\circ}$ wall, the directions of flexible media of two models are different.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.561-566
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• 2008

Recently, because of development of the high speed train technology, the vibration loads by train is significantly increased ever than before. This buried gas pipelines are exposed to both repeated impact loads, and, moreover, they have been influencing by vibration loads than pipeline which is not located under vehicle loads. The vibration characteristic of pipeline is examined by dynamic analysis, and variable is only train speed. Since an effect of magnitude of vibration loads is more critical than cover depth, as increasing the train speed, the vibration speed of buried pipelines is also increased. The slope of vibration velocity is changed by attenuation of wave, at train speed, 300 km/h. From the analysis results, the vibration velocity of pipelines is satisfied with the vibration velocity criteria which are established by Korea Gas Corporation. The results present operation condition of pipelines under rail loads has fully sound integrity based on KOGAS specification.

• Journal of the Korean Geotechnical Society
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• v.17 no.3
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• pp.33-39
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• 2001

지진 등에 의해 유발된 동 하중에 의한 지반-구조물 계의 응답은 지반-구조물사이의 경계에서의 마찰특성과 미끄러짐에 의해 크게 영향을 받게 된다. 본 논문에서는 진동대(Shaking table)를 이용하여 조립토와 건설재료(steel)와의 경계에서 지반으로부터 지중구조물에 전달되는 전단응력의 전달정도를 파악하기 위한 실험을 실시하였다. 본 실험에서 설정한 미끄러짐속도 범위 내에서는 미끄러짐속도 변화에 따른 조립토와 건설재료(steel) 사이의 동마찰계수의 변화가 작다는 사실이 관찰되었다. 그리고 조립토의 평균유효입경의 변화가 동마찰계수에 미치는 영향도 함께 조사되었으며, 이 동마찰계수를 같은 조립토에 대한 평면변형률시험을 통해 얻어진 최대내부마찰각으로부터 구한 마찰계수와 비교하여 정량화하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.1
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• pp.145-151
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• 1991

The final purpose of this study is to examine the uses of coal ash, by-product from thermal power plant as a type of filling-embankment materials and the reuses of ash ponds. In this time, to investigate the dynamic properties, we made the test piece specimen with coal ashes, and obtained the damping ratio. In place(ash pond), the damping property by underground wall was investigated before and after soil improvements. The damping ratio of coal ash test piece specimen of 12% cement is the highest and that of 9% cement or chemical grout, that of 6% cement is in order. In same coal ash test piece, the damping ratio increases with decreasing the void ratio. In conclusion, it could be said that the damping ratio increases with the stiffness of materials. In the ash pond, the damping effect is the most when trench is set through the vibration wave propagation course, and when soil is improved the higher stiffness of the improved soil is, the more damping effect appeared. It is justified to obtain not only the dropping of permeability and the strength increase, but also the damping effect fairly by soil improvements.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.99-105
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• 2011

When a certain magnitude earthquake occurs, serious damage for human and properties is a major concern for most of the subway stations which were not applied for earthquake resistant design. Consideration and experimental verification for ground and structural behavior based on soil-structure interaction relation are required to evaluate seismic performance of the subway station as embedded structures. For 1/60 scaled subway station model, centrifuge modeling shaking table test is performed using Kobe and Northridge earthquakes. Compare to displacements and moments of the underground and structure obtained by soil response analysis and response displacement method based on experimental results, this paper shows how to evaluate seismic performance of subway station.