• Title/Summary/Keyword: Large scale model test

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Evaluation on bridge dynamic properties and VIV performance based on wind tunnel test and field measurement

  • Yang, Yongxin;Ma, Tingting;Ge, Yaojun
    • Wind and Structures
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    • v.20 no.6
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    • pp.719-737
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    • 2015
  • Full scale measurement on the structural dynamic characteristics and Vortex-induced Vibrations (VIV) of a long-span suspension bridge with a central span of 1650 m were conducted. Different Finite Element (FE) modeling principles for the separated twin-box girder were compared and evaluated with the field vibration test results, and the double-spine model was determined to be the best simulation model, but certain modification still needs to be made which will affect the basic modeling parameters and the dynamic response prediction values of corresponding wind tunnel tests. Based on the FE modal analysis results, small-scaled and large-scaled sectional model tests were both carried out to investigate the VIV responses, and probable Reynolds Number effects or scale effect on VIV responses were presented. Based on the observed VIV modes in the field measurement, the VIV results obtained from sectional model tests were converted into those of the three-dimensional (3D) full-scale bridge and subsequently compared with field measurement results. It is indicated that the large-scaled sectional model test can probably provide a reasonable and effective prediction on VIV response.

Stability of A Surcharged Tunnel under the Effect of Pre-Loading on the Adjacent Braced Wall (근접한 흙막이벽체에 가하는 선행하중의 영향을 받는 상재하중 재하 터널의 안정)

  • Kim, IL;Lee, Sang Duk
    • Journal of the Society of Disaster Information
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    • v.4 no.2
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    • pp.10-27
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    • 2008
  • When the ground is excavated adjacent to the existing tunnel, which is loaded by the surcharge on the ground surface, the tunnel stability would be very sensitive to the deformation of the ground induced by the horizontal displacement of braced wall. The stability of the existing surcharged tunnel could be controlled by pre-loading on the braced wall. In this paper, it was investigated, if it would be possible to keep the existing surcharged tunnel stable by preventing the horizontal displacement of a braced wall by imposing the pre-loading during the ground excavation. For this purpose, large scale model tests were performed in a scale 1/10 at the test pit which was 2.0m in width and 6.0m in height and 4.0m in length. Isotropic test ground was constructed homogeneously by wet sand. Model tunnel was constructed in the test ground. Surcharge was loaded on the ground surface above the tunnel. During the tests, the behavior of model tunnel and model braced wall was measured. Numerical analyses were also performed in the same condition as the tests. And their results were compared to that of the model tests. Consequently, the effect of a surcharge could be compensated by imposing the pre-loading on the braced wall. The existing tunnel and the braced wall could be kept stable by preventing the horizontal displacement of the braced wall through pre-loading, although the tunnel is surcharged.

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Development of the Engagement Control Software Architecture Based on UML 2.0 Model (UML 2.0 모델 기반의 교전통제 소프트웨어 아키텍처 개발)

  • Yoo, Myong-Hwan;Bae, Jung-Il;Shin, Jin-Hwa;Cho, Kil-Seok
    • Journal of the Korea Institute of Military Science and Technology
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    • v.10 no.4
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    • pp.20-29
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    • 2007
  • The engagement control software embedded in the weapon control computer of the fire control center for air defense missile system is large-scale real-time software. The use of typical software development methodologies is not appropriate to develop such large-scale embedded software in terms of reusability, reliability, and productivity for the reason that it is significantly complicated, and highly dependent on hardware platforms and developers. In this paper, a model-based software architecture using components based on UML 2.0 for the engagement control software is presented in order to solve these problems. This software architecture is verified using the black-box test, the scenario-based test, and the Ethernet packet monitoring test methods. The results demonstrate that the developed software architecture can be employed to enhance reusability, maintainability, and productivity of large-scale embedded software.

The Study of Development and Calibration for the Real Scale Fire Test Facility (실대형화재평가장치의 개발 및 안정화에 관한 연구)

  • Yoo, Yong-Ho;Kim, Heung-Youl;Shin, Hyun-Jun
    • Fire Science and Engineering
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    • v.22 no.1
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    • pp.37-44
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    • 2008
  • The reduced scale fire test provides basic data but it is not enough to analysis real fire problem directly because there is no exact analogy theory between a real fire and the reduced scale model. Therefore, we have developed the 10 MW large scale calorimeter in order to real scale fire test. This advanced large scale calorimeter used for physical properties such as a heat release rate, based upon consumption of $O_2$ method. Using the heptane pool fire, we carried out the calibration in order to evaluation for heat release rate. It is approve that this facility has the reliability and it is capable of applying to the advance fire research in the future.

Analytical study on seepage behavior of a small-scale capillary barrier system under lateral no-flow condition

  • Byeong-Su Kim
    • Geomechanics and Engineering
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    • v.35 no.1
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    • pp.13-27
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    • 2023
  • The model production for large-scale (lateral length ≥ 2.0 m) capillary barrier (CB) model tests is time and cost-intensive. To address these limitations, the framework of a small-scale CB (SSCB) model test under the lateral no-flow condition has been established. In this study, to validate the experimental methodology of the SSCB model test, a series of seepage analyses on the SSCB model test and engineered slopes in the same and additional test conditions was performed. First, the seepage behavior and diversion length (LD) of the CB system were investigated under three rainfall conditions. In the seepage analysis for the engineered slopes with different slope angles and sand layer thicknesses, the LD increased with the increase in the slope angle and sand layer thickness, although the increase rate of the LD with the sand layer thickness exhibited an upper limit. The LD values from the seepage analysis agreed well with the results estimated from the laboratory SSCB mode test. Therefore, it can be concluded that the experimental methodology of the SSCB model test is one of the promising alternatives to efficiently evaluate the water-shielding performance of the CB system for an engineered slope.

Crash Analysis of Railway Vehicle Structure Using Scale Model (축소모형을 이용한 철도차량 충돌 해석 기법 연구)

  • 김범진;허승진
    • Proceedings of the KSR Conference
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    • 2002.10a
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    • pp.54-59
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    • 2002
  • In general, the aluminum extrusions are used to the light construction of the high speed rail vehicle structures. However, the research works ok the crashworthy design of the high speed rail vehicle structures are not published sufficiently because the crash test of high speed rail vehicle structures costs high and is complicated. So, a method that can predict crash characteristics of a large size structure like a high speed tail vehicle should be suggested. In this study, the scale model studies are performed to predict the impact energy absorption characteristics of full scale model. In the first place, we verified the theory of scale law using FE-simulation from the crashworthiness point of view. Secondly, we performed the crush test using scale model, made of aluminum sub structure. As a result, we could predict the crash characteristics using scale model by 10∼20% error.

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Investigation of Large-scale Transmission Tower Grounding Grid with High Amplitude and Uniform Flowing Impulse Current

  • Yang, Shuai;Huang, Jiarui;Wei, Shaodong;Zhou, Wenjun
    • Journal of Electrical Engineering and Technology
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    • v.13 no.5
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    • pp.2050-2058
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    • 2018
  • Impulse characteristic of transmission tower grounding grid is needed for lightning protection of transmission line. This paper describes an outdoor experimental test facility established for large-scale grounding grid of transmission tower, made up of four impulse current generators and a circle current return electrode. The amplitude of impulse current is up to 100 kA. The results of the CDEGS simulation and GPR measurement reveal the uniform current distribution in the test arrangement. An impulse test for a square electrode with extended conductors is carried out in condition of three current waveforms with different amplitude. Based on the electrical network model and iterative algorithm method, a calculation model is proposed to simulate the impulse characteristic of large-scale grounding grid considering soil ionization. The curve of impulse resistance against the current amplitude shows the soil ionization both from the simulation and test. Deviation between the simulation and test result is less than 15%.

A study on the vehicle fire property using the large scale calorimeter (대형칼로리미터를 이용한 차량 화재 특성에 관한 연구)

  • Yoo, Yong-Ho;Kim, Heung-Youl;Shin, Hyun-Jun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.9 no.4
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    • pp.343-349
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    • 2007
  • The reduced scale fire test provides basic data but it is not enough to analysis real fire problem directly because there is no exact analogy theory between a real fire and the reduced scale model. Therefore we have developed the large scale calorimeter in order to the real scale fire test. This advanced large scale calorimeter used for physical properties such as a heat release rate, based upon consumption of $O_2$ method. Using this large scale calorimeter, we cameo out the real scale vehicle fire test in order to evaluation for heat release rate. We obtained the calculated result for HRR $2.3{\sim}3.4\;MW$ and this result is very similar to the PIARC candidate HRR. It is approve that this facility has the reliability and it is capable of applying to the advance fire research in the future.

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Development of the intermittency turbulence model for a plane jet flow (자유 평면 제트유동 해석을 위한 간혈도 난류모델의 개발)

  • 조지룡;정명균
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.3
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    • pp.528-536
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    • 1987
  • In a turbulent free shear flow, the large scale motion is characterized by the intermittent flow which arises from the interaction between the turbulent fluid and the irrotational fluid of the environment through the mean velocity gradient. This large scale motion causes a bulk convection whose effect is similar to the spatial diffusion process. In this paper, the total diffusion process is proposed to be approximated by weighted sum of the bulk convection due to the large scale motion and the usual gradient diffusion due to small scale motion. The diffusion term in conventional .kappa.-.epsilon. model requires on more equation of the intermittency transport equation. A production term of this equation means mass entrainment from the irrotational fluid to the turbulent one. In order to test the validity of the proposed model, a plane jet is predicted by this method. Numerical results of this model is found to yield better agreement with experiment than the standard .kappa.-.epsilon. model and Byggstoyl & Kollmann's model(1986). Present hybrid diffusion model requires further tests for the check of universality of model and for the model constant fix.

A Study on the Similitude of Member Behavior for Small-Scale Modeling of Reinforced Concrete Structure (철근콘크리트 축소모델의 부재거동 상사성에 관한 연구)

  • 장진혁;이한선
    • Proceedings of the Korea Concrete Institute Conference
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    • 1995.10a
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    • pp.187-192
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    • 1995
  • Four types of experiments were performed to check the similitude of member behavior between prototype and 1/10 scale models:(1) Test of slender columns with P- effect, (2)Test of short columns with and without confinement steel, (3)Test of simple beams without stirrups, and (4)T-beam test. Based on the results of experiments, the conclusions were made as follows : (1) The P- effect of slender columns can be almost exactly represented by 1/10 acale model. (2)The effect of confinement on short columns by the hoop steel can also roughly simulated by 1/10 scale model. (3)The failure modes of simple beams models were the yielding of tension steel followed by large diagonal tension cracking+compressive concrete failure. (4)The behaviors of prototype and 1/10 scale model in T-beams appear very similar.

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