• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.1
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• pp.10-20
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• 2017

This study presents the feasibility of CFD(computational fluid dynamic) analysis using the flow angularity wind tunnel test technique. The CFD analyzed data by the flow angularity technique has been constructed as the database to get store trajectories by 6-DOF simulation. The database has been checked out store aerodynamic coefficients by the analyses at each position under wing. After that process, the simulated trajectories by database have been compared with the store trajectories by CTS(Captive Trajectory Simulation) of CFD. The trajectories provided by the database of flow angularity have a good agreement with the store trajectories by CFD.

• Smart Structures and Systems
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• v.22 no.4
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• pp.459-468
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• 2018

In this paper, the effect of non-persistent joints was determined on the behavior of concrete specimens subjected to biaxial loading through numerical modeling using particle flow code in two dimensions (PFC2D). Firstly, a numerical model was calibrated by uniaxial, Brazilian and triaxial experimental results to ensure the conformity of the simulated numerical model's response. Secondly, sixteen rectangular models with dimension of 100 mm by 100 mm were developed. Each model contains two non-persistent joints with lengths of 40 mm and 20 mm, respectively. The angularity of the larger joint changes from $30^{\circ}$ to $90^{\circ}$. In each configuration, the small joint angularity changes from $0^{\circ}$ to $90^{\circ}$ in $30^{\circ}$ increments. All of the models were under confining stress of 1 MPa. By using of the biaxial test configuration, the failure process was visually observed. Discrete element simulations demonstrated that macro shear fractures in models are because of microscopic tensile breakage of a large number of bonded discs. The failure pattern in Rock Bridge is mostly affected by joint overlapping whereas the biaxial strength is closely related to the failure pattern.

• International Journal of Aeronautical and Space Sciences
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• v.1 no.2
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• pp.68-74
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• 2000

A comparative wind tunnel testing of an airplane model was performed at the Korea Aerospace Research Institute Low Speed Wind tunnel(KARI LSWT). The model used for the comparative test was a seaplane model from the Glenn L. Martin Wind(GLM) Tunnel of University of Maryland, U.S.A. The 6-component external balance used in force and moment measurement is pyramidal type, which is a precision device that has strain gauge-type load cell inside of balance and the virtual center of the balance coincides with the tunnel centerline. Image method is adopted to eliminate the tare and interference of the model support, and to correct the flow angularity to the model also. Test results from KARI LSWT were compared with the results from GLM tunnel.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.85-88
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• 2005

The stone powder sludge occurred at aggregate production process is classified the specified waste, so it is disposed by appropriate method. But the problems of the shortage of the disposal-site, the environment pollution, and the increase of disposal cost can be occurred in handling process, therefore the stone powder sludge is required the development of recycling technique. The stone powder sludge includes SiO2 of about $63\%$. This characteristic is important at the production of hardened specimens under condition of hydro-thermal reaction. In this study, we investigated the strength properties of concrete used stone powder sludge as siliceous material. The test results under condition of hydro-thermal reaction shows the two main facts. The first, the stone powder sludge is affected to fluidity because the surface of the stone powder sludge has characteristics of flakily and angularity. The second, weight content of the stone powder sludge, is not effective factor to the properties of strength.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.2
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• pp.130-135
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• 2007

Wind tunnel test for Smart UAV power model has been conducted at KARI LSWT for about 3 months. The static model is used for the base plane and the power effect of tilt rotor is simulated by the tilt-rotor test rig installed in the test section. Although the genuine power effect is the difference between power-on and off tests. The existence of struts for power effect test produced unwanted form of interference and caused the change in flow angularity. To precisely evaluate power effect, a special approach is applied to Smart UAV test.

• Structural Engineering and Mechanics
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• v.69 no.1
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• pp.51-67
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• 2019

In this paper, the anisotropy of tensile behaviours of layered rocks consisting internal notch has been investigated using particle flow code. For this purpose, firstly calibration of PFC2D was performed using Brazilian tensile strength. Secondly Brazilian test models consisting bedding layer was simulated numerically. Thickness of layers was 10 mm and layered angularity was $90^{\circ}$, $75^{\circ}$, $60^{\circ}$, $45^{\circ}$, $30^{\circ}$, $15^{\circ}$ and $0^{\circ}$. The strength of bedding interface was too high. Each model was consisted of one internal notch. Notch length is 1 cm, 2 cm and 4 cm and notch angularities are $60^{\circ}$, $45^{\circ}$, $30^{\circ}$, $15^{\circ}$ and $0^{\circ}$. Totally, 90 model were tested. The results show that failure pattern was affected by notch orientation and notch length. It's to be noted that layer angle has not any effect on the failure pattern. Also, Brazilian tensile strength is affected by notch orientation and notch length.