• Wind and Structures
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• 제20권6호
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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.

• 한국재난정보학회 논문집
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• 제4권2호
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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.

• 한국군사과학기술학회지
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• 제10권4호
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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.

• 한국화재소방학회논문지
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• 제22권1호
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• pp.37-44
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• 2008

최근 화재와 관련된 연구가 활발해지면서 축소모형실험 등을 통한 연구가 진행되어 왔다. 그러나 실물화재 실험과의 직접적인 상관관계를 설명하기에는 충분하지 못하기 때문에 실물화재에 대한 관심이 증가되어 왔다. 따라서 본 연구에서는 산소소모율법을 적용한 10 MW급 라지스케일로리미터를 개발하였으며, 헵탄 풀 화재를 이용한 발열량 보정을 수행하였다. 그 결과 신뢰성 높은 보정결과를 얻었으며, 보다 진보적인 실물화재연구에 적용할 수 있음을 확인할 수 있었다.

• Geomechanics and Engineering
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• 제35권1호
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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 (L_D) 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 L_D increased with the increase in the slope angle and sand layer thickness, although the increase rate of the L_D with the sand layer thickness exhibited an upper limit. The L_D 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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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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.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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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%.

• 한국터널지하공간학회 논문집
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• 제9권4호
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• pp.343-349
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• 2007

터널 화재와 관련된 축소모형실험연구는 기본적인 데이터는 제공할 수 있지만, 축소모형과 실물화재간의 정확한 이론적 상사관계가 정립되어 있지 않기 때문에 실물화재에 대한 직접적인 분석을 하기에는 어려움이 따른다. 이에 산소소모율법을 적용하여 열방출율과 같은 물리량의 측정이 가능한 실물화재실험장치인 대형칼로리미터를 개발하였다. 이를 이용하여 차량의 화재시 열방출율을 측정하기 위한 실물실험을 실시하였으며, 그 결과 차량의 열방출율은 $2.3{\sim}3.4\;MW$로 측정되었다. 이는 PIARC에서 권고하는 차량의 열방출율과 유사한 범위로서 개발된 실물화재평가장치의 신뢰성을 확인할 수 있음은 물론이고 향후 관련 연구에 매우 유용하게 이용될 수 있을 것이다.

• 대한기계학회논문집
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• 제11권3호
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• pp.528-536
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• 1987

본 연구에서는 간헐적인 유동에 의거한 체적 대류 모델을 설정하고, 구배 확 산 모델에 유동장의 중심부와 외부에서 서로 다른 무게값을 부여하는 혼성 확산 모델 (hybrid diffusion model)을 제안하며, 이 모델을 검증하기 위한 첫 단계로서 평면 제 트 유동에 대하여 수치 계산을 수행하다. 여기에는 간헐도에 대한 난류 전달 방정식 이 필요한데 이 방정식의 생성항(production term)은 곧 외부의 비회전 유동이 난류성 유체로 유입되는 정도를 의미하게 된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 가을 학술발표회 논문집
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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.