• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.119-121
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• 2011

플로팅 구조물의 거동은 함체의 크기에 따라 많은 영향을 받는 것으로 알려져 있다. 그에 따라 함체의 거동을 표현하기 위한 해석모델은 해석의 단순성, 파랑하중과의 상호작용의 연계정도를 고려하여 그 형태 또한 달라지게 된다. 해석모델에는 함체에 발생하는 진동을 효과적으로 저감시키기 위한 진동저감시스템을 포함하는 경우도 있다. 함체의 해석모델에 진동저감시스템의 해석모델이 연계되면 이들 해석모형이 상호결함된 통합모형은 더욱 복잡한 경향을 가지게 된다. 본 연구에서는 함체의 해석모형을 강체거동을 하는 단순한 모형으로 가정하고 해석모형이 가지는 동적특성을 ICA기법을 통하여 효과적으로 추정하는 기법을 다룬다. 이를 위하여 실험과 ICA 기법을 이용하여 동적추정이 가능한지를 평가해보고 이를 플로팅 구조물에 적용하기 위한 기법을 다룬다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.171-178
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• 2008

The object of this study is to propose a rate of vibration increase in the analysis of temporary rail non-fixed in the vertical direction and characterize the nonlinear dynamic behavior of temporary rail while considering longitudinal and latitudinal load, vibration and lifting. The rate of vibration increase is proposed through measurement of an actual structure that is largely affected by loading and vibration of the superstructure. Dynamic behavior was additionally characterized by the dynamic response resulting from nonlinear dynamic finite element analysis with vehicle loading, including the rate of vibration increase. As a result, the rate of vibration increase by the vibration of an Auto Bar Machine is determined as 7% and the maximum stress in the analysis of the nonlinear rail is increased 14.5% over that of linear rail, and temporary rail is shown to be very sensitive to the velocity of the superstructure.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.222-228
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• 2008

We conducted a dynamic analysis of an underwater test collector, which operates on extremely soft soil of deep-seafloor. The underwater test collector consists of nodule pick-up device, vehicle tracks, nodule crusher, loading frame and electric-electronic system. The weight of underwater test collector is about 8600 kg. The average normal pressure, that the underwater test collector supports, is about 6.0 kPa. The dynamic analysis model of underwater test collector is developed using commercial software RecurDyn-LM and Visual Fortran 90. A terramechanics model of extremely soft soil is implemented to the software based on user-written subroutine and applied to the dynamic analysis of the underwater test collector model. The dynamic responses of test collector are studied with respect to track velocities, terrain conditions, and coefficients of added mass and drag.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.186-193
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• 2010

Track system and periodic live load are characteristics of railway bridges. In the design and construction of railway bridge, periodic live load increases the importance of dynamic behavior. And It is well known that behavior of railway bridge may be affected by track system in real bridge. Through experimental study, static and dynamic behaviors were investigated. Deflection and stress due to bending moment were measured, the location of neutral axis of each section, natural frequency, damping ratio were analyzed for each three track systems - girder only, installed ballast track system and installed concrete slab track system. According to measured values for the each type of track system, concrete track system increases the stiffness of bridge by 50%, and ballast system does by 7%, dynamic responses of structure change linearly with the magnitude of load and location of neutral axis of each sections varies with each track system. Damping ratio is almost equal without and with track. Therefore, the effects of track system on the integral behaviors of railway bridge can not be ignored in the design of bridge, especially in the case of concrete slab track system. So study of the quantitative analysis method for effects of track system must be performed.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.4
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• pp.93-104
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• 2000

적충되어 있는 다중 블록 시스템은 역사적 건물이나 문화재등에 자주 사용되고 있다. 이러한 구조시스템은 지진에 매우 취약하고, 특히 세장한 구조물인 경우에는 낮은 수준의 지반가속도에 대해서도 전도가 일어날 수 있다. 지진으로부터 이러한 구조물을 보호할 수 있는 방법중의 하나로써 지진격기받침의 사용을 들 수 있으나, 아직 격리받침이 설치되어 있는 다중블록의 거동에 대해서는 잘 알려지지 않는 실정이다. 이 논문에서는 각각 P-F 시스템, FPS, LRB 시스템이 설치되어 있을때의 세장한 강체 블록의 동적거동에 대해 살펴보았다. P-F 시스템과 FPS에서의 마찰모델은 Coulomb의 마찰법칙을 이용하였도, 상부구조물은 붙음(stick)모드와 록킹(rocking) 모드만이 존재하도록 가정하였다. 충격은 개별요소법(distinct element method, DEM)을 이용해 기술하였고, 조화입력운동에 대한 응답을 조사하였다.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.441-448
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• 2011

It is very important that establishing the valve train equations and representing the behavior of the valve train parts. To maintain the specific efficiency of running engine, the cam profile of valve train has more specific influence on the adequate behavior of the valve train than a valve clearance, heat-resistance and durability of parts. The polynomial cam, the multipol cam and polydyne cam profie are widely used to represent cam behaviour. In this study, using polydyne cam design profile equations which is more adequate for representing high speed engine, the geometrical modeling and mathmatical variable analysis are established to analysis the valve behaviour.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.9
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• pp.791-799
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• 2016

To ensure the reliability and safety of various mechanical systems in accordance with their high-speed usage, it is necessary to evaluate the dynamic deformation behavior of structural materials under impact load. However, it is not easy to understand the dynamic deformation behavior of the structural materials using experimental methods in the high strain-rate range exceeding $10^4\;s^{-1}$. In this study, the Taylor bar impact test was conducted to investigate the dynamic deformation behavior of metallic materials in the high strain-rate region, using a high-speed photography system. Numerical analysis of the Taylor bar impact test was performed using AUTODYN S/W. The results of the analysis were compared with the experimental results, and the material behavior in the high strain-rate region was discussed.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.2
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• pp.1-12
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• 1998

The seismic behaviour of rotating machine-foundation systems subjected to six-component nonstationary earthquake ground accelerations is analyzed. The rotating machine-foundation system is idealized by using discs, rotating shaft, fluid-film journal bearings, pedestals, and space frame foundation. Thus, governing equations of motion for the rotating machine-foundation system are obtained by considering Gyroscopic effect, Coriolis effect, dynamic characteristics of fluid-film journal bearings, and translational and rotational motions of seismic rigid base. The influences due to Gyroscopic effects, Coriolis effects, and rotational motions of seismic base on the overall structural response are demonstrated by a numerical example. The results show that the inclusion of base rotations and Gyroscopic effects contributes significantly to the system response.

• Journal of the Korean Geophysical Society
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• v.9 no.2
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• pp.77-86
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• 2006

Aplications of the real-time kinematic GPS surveying and inertial measurement unit have been beingRTK GPS allows the use of a static base station and remote rover unit to allow for data collectionwithin several seconds and in real time. It is useful for monitoring the behaviors of massive structureslike bridges. And this study purposed to implement a method of deciding the acurate dynaimc attitudeof structures by IMU. In this study, among GPS methods, we used RTK GPS to analyze the precisionof monitoring and then on the basis of it, we developed a monitoring system using RTK GPS anda deviation betwen observation values, X axis was 1mm, Y axis was 1mm and Z axis 2.2mm. I tturned out that it was possible to monitor and measure structures by RTK GPS and IMU.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.244-244
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• 2003