• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.4
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• pp.197-203
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• 2001

This study presents the results of shaking table test of scaled model structures with added viscoelastic dampers, which are considered to be one of the most efficient means of upgrading existing structures against seismic loads. The experimental results were compared with those from analysis based on the linear modeling of viscoelastic dampers. The parameters obtained from free vibration test were utilized in the analysis. According to the results the added viscoelastic dampers turned out to be effective in reducing the responses of the model structures. It was also found that the analysis with linear modeling of viscoelastic dampers could simulate the test results accurately.

• Wind and Structures
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• v.16 no.2
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• pp.137-156
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• 2013

A wind tunnel test of a scaled-down model and field measurement were effective methods for elucidating the aerodynamic behavior of a chimney under a wind load. Therefore, the relationship between the results of the wind tunnel test and the field measurement had to be determined. Accordingly, the set-up and testing method in the wind tunnel had to be modified from the field measurement to simulate the real behavior of a chimney under the wind flow with a larger Reynolds number. It enabled the results of the wind tunnel tests to be correlated with the field measurement. The model surface roughness and different turbulence intensity flows were added to the test. The simulated results of the wind tunnel test agreed with the full-scale measurements in the mean surface pressure distribution behavior.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.3
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• pp.10-16
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• 2004

In this paper the aeroacoustic characteristics of a helicopter main rotor system is measured by using a pair of scaled rotor blades. A low noise rotor test jig is developed for noise measurement and the rotational speed, thrust and torque are measured simultaneously in order to match the aerodynamic conditions with the full scale rotor. The accuracy of the force measurement device was checked through a calibration procedure. The measured thurst and torque with a 1.2m rotor are compared to the results of analytical prediction and showed that the thrust data at various rotational speed followed the prediction relatively well, but the torque data considered less accurate. It is also found that the background noise level of the test rig is sufficiently low, and the measured noise level from the rotor can be scaled with rotor tip speed. However, the Mach number dependancy and the directivity changes depend on the noise source characteristics.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.641-652
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• 2007

In this paper, a half-scaled substructure test was performed to evaluate the buckling and structural safety of an existing transmission tower subjected to wind load. A loading scheme was devised to reproduce the dead and wind loads of a prototype transmission tower, which uses a triangular jig that is mounted on the reduced model to which the similarity law of a half length was applied. As a result of the preliminary numerical analysis carried out to evaluate the stability of a specimen for the design load, is was confirmed that the calculated axial forces of tower leg members were distributed to $80{\sim}90%$ of an admissible buckling load. When the substructured transmission tower was loaded by 270% of its maximum admissible buckling load, it was failed due to the local buckling that is occurred in joints with weak constraints for out-of-plane behavior of leg members. By inspection of load-displacement curves, displacements and strains of members, it is considered that this local buckling was due to additional eccentric force by unbalanced deformation because the time that is reached to yielding stress due to the bending moment is different at each point of a same section.

• Geotechnical Engineering
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• v.13 no.3
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• pp.63-76
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• 1997

To investigate the engineering characteristics of crushed rockfill material, the large-scaled triaxial tests have been carried out, The rpckfill is made from the greywacke, and the 3 parallel gradations with different maximum particle size(dmu=38.1mm, 25.4mm and 19.1mm) were designed for the test. The dimension of the specimen is 300mm in diameter and 600mm in height, and the applied confining stress varied from 5t/$51.6^{\circ}$ to 60t/$51.6^{\circ}$. The test results show that the influence of the maximum particle size on the stress -strain r$51.6^{\circ}\; to\; 40.5^{\circ}$ when the confining stress increases from 5t/$51.6^{\circ}$ to 60t/$51.6^{\circ}$ The hyperbolic parameter values estimated from the test result for rockfill are much different from the recommended values by Duncan et. at(1980) for GW and GP material, especially in the $\phi$ ad K-values.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.1
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• pp.59-68
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• 2013

This paper presents the fundamental study on the field applicability of new-type steel fiber improved the existing shape. In this study, the theoretical reviews and the laboratory test programs were carried out to evaluate the mechanical characteristic of the new-type of steel fiber. The steel fiber sticking coefficient of new-type steel fiber was estimated from the test results. The laboratory scaled shotcrete rebound tests were also performed to analysis the field applicability of New-type steel fiber shotcrete and the mechanical behaviour of New-type steel fiber shotcrete were compared with that of the existing steel fiber shotcrete. It was found that the strength characteristic of New-type steel fiber shotcrete was increased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.37-46
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• 2014

This paper describes the conceptual design and development test procedure of a unmanned scaled-down personal air vehicle(PAV) with drive and flight dual mode capability. Trade studies on operational requirements led to the suggestion of a quad tilt prop platform which has nacelle tilt capability with multi rotor configuration. Motors for propeller propulsion and driving mechanism were integrated into a single nacelle, then they were implemented by nacelle tilt mechanism for conversion between the drive and the flight modes. Primary design parameters and initial specifications were confirmed through conceptual design, then functional tests were performed with the test platforms for the drive and the flight modes.

• Geophysics and Geophysical Exploration
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• v.12 no.4
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• pp.355-360
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• 2009

This paper presents mobile robot based down-scale mineral resources exploration test system for the USN (Ubiquitous Sensor Network) based exploration. The system emulates the actual exploration environment. Underneath the metal free test plate, a metal object is attached. A magneto-meter mounted mobile robot runs around on the plate to find the metal. The measured magneto-meter values are transferred to the host PC via wireless network. The system enables to improve the reliability of simulation as well as to help efficient exploration system design. Metal-detecting experiments were carried out to illustrate the efficiency of the proposed system.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.819-824
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• 2010

Model test was performed for new earth retention system that is a kind of truss tower with non-supported excavation. For the model test, a dimensional analysis of the full-scaled truss tower system was performed. The horizontal displacement of the wall, bending stress acting on TTS system were measured during construction simulation. From the measurements, the performance of the truss tower system was investigated.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.595-606
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• 2009

This paper presents the characteristics of stress transfer around carven due to cavern size and rock joint properties by laboratory model test. In order to perform this study, eight different scaled model tests were carried out according to excavation stage. The limited numerical analysis were also performed to verify the model test results. The amount of stress transfer around the cavern is increased and then decreased by longitudinal arching effect according to tunnel excavation. It is founded that the stress developed around the cavern during excavation is increased when the cavern size and joint orientation are increased. It is also investigated that shear behaviour (such as stress, deformation) developed around cavern is considerably depended on the characteristic of fill material, dip and direction of joints. It is suggested that the behaviour will be verified throughout the 3D numerical prediction.