• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1343-1349
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• 2010

This paper presents the behavior of the soil based on the Gap Parameter during the Shield TBM tunnel excavation in sandy soil. This study reproduced the tunnel before and after the excavation according to the diameter of the tunnel, water ratio and depth to execute a Scaled Model Test and analyzed the behavior change of the upper soil. As a result, tunneling after for soil stress decreased was similar in all the Case. In addition, the soil stress decreased was in water ratio increases.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.6
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• pp.1130-1137
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• 2009

This paper describes a scaled model development of PMSG wind power system using wind turbine simulator and matrix converter. The wind turbine simulator, which consists of an induction motor with vector drive, calculates the output torque of a specific wind turbine using simulation software and sends the torque signal to the vector drive after scaling down the calculated value. The operational feasibility of interconnected PMSG system with matrix converter was verified by computer simulations with PSCAD/EMTDC software. The feasibility of hardware implementation was conformed by experimental works with a laboratory scaled-model of wind power system. The simulation and experimental results confirm that matrix converter can be effectively applied for the PMSG wind power system.

• KIEE International Transactions on Power Engineering
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• v.5A no.2
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• pp.159-170
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• 2005

This paper presents the design and development of a scaled down physical model for power Distribution Automation (DA) system simulation. The developed DA system simulator is useful in providing hands-on experience to utility engineers / managers to familiarize with the DA system and gain confidence in managing the power distribution system from the computer aided distribution control center. The distribution automation system simulator can be effectively used to carry out further research work in this area. This also helps the undergraduate and graduate students to understands the power distribution automation technology in the laboratory environment. The developed DA simulator has become an integral part of a distribution automation lab in the Electrical Engineering Department at Indian Institute of Technology Kanpur in India.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.159-169
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• 2008

In general, it is considered that a pillar between closely-spaced tunnel is sensitive for stress concentration. Stability of a pillar is key factor for excavation of closely-spaced tunnel. In this paper, the study is focused on tracing the behaviors, displacement and plotting damages around tunnels that is modelled with Particle Flow Code, $PFC^{2D}$. Parametric study was performed with changing distance between center of tunnels and coefficient of earth pressure(K). Scaled-model tests were also carried out to validate a numerical analysis model. It was found that $PFC^{2D}$ could show dynamic visualized result in quite good agreement with the experimental test.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.571-575
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• 2000

The physical properties of the spatial model, mass, stiffness and damping matrix, can be defined by a specific natural frequency, damping ratio and mode shape. These modal parameters can be determined from a set of frequency response function(FRF) measured by exciting the structure and measuring the responses at various points around the structure. In this paper, The Transfer Matrix is obtained by experimental modal analysis for the 3-story scaled building model which TMD is installed on top and the physical properties of the spatial model is determined using the residue matrix and the location of poles from FRF measurement using polynomial curve fitting methods.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.353-353
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• 2000

To control a light weight flexible manipulator, a composite fuzzy controller is proposed. The controller is designed based on two time scaled models. A singular perturbation technique is applied for deriving the models. The proposed controller, however, does not use the complex equilibrium manifold equations, which are usually needed in the controller based on the two time scaled models. The controller for a slow sub-model and a fast sub-model are T-S type fuzzy controllers, which use 3 linguistic variables for each sub-model. A step trajectory is used in simulations as a reference trajectory of joint motions. The results of simulations with the proposed controller show excellent damping of flexible motions compared to a controller with derivative control of flexible motions.

• International Journal of Railway
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• v.2 no.2
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• pp.93-97
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• 2009

The experiments for aerodynamic characteristics of railway acoustic screen are performed using 1/61 scaled-down moving model rig facility which employs an axis symmetry and one wire guidance method. The launching mechanism is an air-gun type. The train model for the experiment is the high speed train (Korea Train Express: KTX) and the tested speed is about 300 km/h. The tested train length is 61 em which is corresponding to two units of KTX train. The cross sectional area and weight of train model are 0.00264 $m^2$ and 287 g, respectively. The Reynolds number based on the model train length is $1.2{\times}10^7$. The strength of pressure wave is measured using piezo typed pressure sensor. The measured pick value of pressure was as high as 365 Pa in the shortest gap between the acoustic screen and model train. The measured pressure is well compared with the field test data of mc 779-1 [2] values. However, the experimental data were slightly lower than the mc 779-1 values. The results show the model test can be used as a substitute for the field test.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.335-344
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• 2010

This paper presents both of an investigation on the ultimate responses and a verification study on the structural methodology using beam-truss element of steel transmission towers using experimental study. The partially scaled tower which verified with analytical model was fabricated and the horizontal load was applied up to failure in the laboratory. The structural methodology for finite element analyses was verified against experimental results and both the ultimate load capacity and collapse mechanism were shown in the test to give sufficiently accurate results with those of analytical study. It was shown as well that the ultimate failure is primarily attributed to instability of the main posts in the leg parts.

• International Journal of Highway Engineering
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• v.18 no.2
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• pp.51-60
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• 2016

PURPOSES : The applicability of the mechanics-based similarity concept (suggested by Feng et al.) for determining scaled variables, including length and load, via laboratory-scale tests and discrete element analysis, was evaluated. METHODS: Several studies on the similarity concept were reviewed. The exact scaling approach, a similarity concept described by Feng, was applied in order to determine an analytical solution of a free-falling ball. This solution can be considered one of the simplest conditions for discrete element analysis. RESULTS : The results revealed that 1) the exact scaling approach can be used to determine the scale of variables in laboratory tests and numerical analysis, 2) applying only a scale factor, via the exact scaling approach, is inadequate for the error-free replacement of small particles by large ones during discrete element analysis, 3) the level of continuity of flowable materials such as SCC and cement mortar seems to be an important criterion for evaluating the applicability of the similarity concept, and 4) additional conditions, such as the kinetics of particle, contact model, and geometry, must be taken into consideration to achieve the maximum radius of replacement particles during discrete element analysis. CONCLUSIONS : The concept of similarity is a convenient tool to evaluate the correspondence of scaled laboratory test or numerical analysis to physical condition. However, to achieve excellent correspondence, additional factors, such as the kinetics of particles, contact model, and geometry, must be taken into consideration.

• Tunnel and Underground Space
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• v.25 no.5
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• pp.423-434
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• 2015

Scaled model tests were performed to investigate the influence of pillar width, rock strength and isotropy/anisotropy on the stability of twin tunnels. Test models had respectively different pillar widths, uniaxial compressive strengths of modelling materials and model types, where both the deformation behaviors around tunnels and the biaxial pressure data at a time of pillar cracking were analysed. The cracking pressures of the higher strength models were higher than the lower strength models, whereas the percentage of cracking pressure to uniaxial compressive strength of modelling materials showed an opposite tendency. The cracking pressures of the shallower pillar width models were lower than the thicker models, moreover the percentage of that showed a same tendency. It has been found that the pillar width was one of the main factors influencing on the stability of twin tunnels. Model types such as isotropy/anisotropy also influenced on the stability of twin tunnels. The anisotropic models showed lower values of both cracking pressures and the percentage of that than the isotropic models, where the pillar cracks of anisotropic models were generated with regard to the pre-existing joint planes.