• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.838-841
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• 2005

This study was carried out to analyze the effect of wind load on the structural stability of a 50ton articulation type container crane using wind tunnel test and provide a container crane designer with data which can be used in a wind resistance design of an articulation type container crane assuming that a wind load 75m/s wind velocity is applied in an articulation type container crane. Data acquisition conditions for this experiment were established in accordance with the similarity. The scale of an articulation type container crane dimension, wind velocity and time were chosen as 1/200, 1/13.3 and 1/15. And this experiment was implemented in an Eiffel type atmospheric boundary layer wind tunnel with $11.52m^2$ cross-section area. Each directional drag and overturning moment coefficients were investigated and uplift forces at each supporting point due to the wind load were analyzed.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.211-216
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• 2013

A wind generator system model includes wind model, rotor dynamics, synchronous generator, power converter, distribution line and infinite bus. This paper investigates the low-Voltage Ride-Through capability of PMSG wind turbine in a variable speed. The drive train of a wind turbine on 2-mass modeling can observe the shaft torsional vibration when the low-voltage occur. To reduce the torsional vibration when the low-voltage occur, this paper designs suppression control algorithm of the torsional vibration and implements simulation. The simulation based on MATLAB/SIMULINK has validated at the transient state of the PMSG and an experiment using 3kW simulator has validated the LVRT control.

• Wind and Structures
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• v.38 no.6
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• pp.461-475
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• 2024

A reliable wind speed forecasting method is crucial for the applications in wind engineering. In this study, the generalized S-transform (GST) is innovatively applied for wind speed forecasting to uncover the time-frequency characteristics in the non-stationary wind speed data. The improved grey wolf optimizer (IGWO) is employed to optimize the adjustable parameters of GST to obtain the best time-frequency resolution. Then a hybrid method based on IGWO-optimized GST is proposed to validate the effectiveness and superiority for multi-step non-stationary wind speed forecasting. The historical wind speed is chosen as the first input feature, while the dynamic time-frequency characteristics obtained by IGWO-optimized GST are chosen as the second input feature. Comparative experiment with six competitors is conducted to demonstrate the best performance of the proposed method in terms of prediction accuracy and stability. The superiority of the GST compared to other time-frequency analysis methods is also discussed by another experiment. It can be concluded that the introduction of IGWO-optimized GST can deeply exploit the time-frequency characteristics and effectively improving the prediction accuracy.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.2
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• pp.165-170
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• 2011

In this paper, wind force coefficient by wind tunnel experiment is obtained to compute the accurate wind force of the gantry crane model to be used for mobile harbor ship. The first crane model was tested under 20, 30, 40, 52m/s, partially 58m/s and the wind force coefficient is about 2.0 which is very close to the suggested theoretical value. The other is the more reliable crane model and tested under 20, 30, 40m/s also giving the similar realistic wind force coefficient. Also structural analysis of crane model was performed giving the reliable stress level. Since the rolling effect is important for mobile harbor ship, the safety of the crane on the ship needs to be guaranteed. For this, using the computed reaction forces, a tie-down design is suggested which connects the crane and ship to resist the turnover motion of the crane.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.3
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• pp.246-253
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• 2005

An experimenal study on flight control of high-speed AEV(Aero-levitation Electric Vehicle) scale model in wind-tunnel is conducted. The AEV is to fly at very low altitude in predesigned track so that it is always under the wing-in-ground effect. The experiment is intended to fly the scale model to follow the predesigned altitude schedule while holding its attitude (pitch, roll, and yaw). Especially, the altitude changes for climb, cruise, and descent with constant pitch angle are most important maneuvers. The experiment shows that the required mission flights can be performed with appropriate sensors, processors, and actuators.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.371-372
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• 2006

This study was carried out to analyze the effect of wind load on the structural stability of a container crane according to the change of the boom shape using wind tunnel test and provide a container crane designer with data which can be used in a wind resistance design of a container crane assuming that a wind load 75m/s wind velocity is applied in a container crane. Data acquisition conditions for this experiment were established in accordance with the similarity. The scale of a container crane dimension, wind velocity and time were chosen as 1/200, 1/13.3 and 1/15. And this experiment was implemented in an Eiffel type atmospheric boundary layer wind tunnel with $11.52m^2$ cross-section area. Each directional drag and overturning moment coefficients of a container crane according to the change of the boom shape were investigated.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.1
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• pp.1-7
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• 2008

To investigate the appearance of cold water by upwelling effect near Ulsan-Gampo of the southeastern coast in Korea on June, 1999, we carried out a numerical experiment by 3-dimensional diagnostic numerical model. Appearance of cold water by the result of numerical experiment was due to upwelling by wind effect at 50-100m depth near Ulsan-Gampo coast. This result was mused by using a model to 2 times of existing wind magnitude near Busan, Ulsan and Gampo that is 5.0m/sec wind. Therefore, to illustrate the phenomenon of extraordinary marine environment like upwelling event and so forth, appropriate wind data at sea should be used instead of those on land.

• Atmosphere
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• v.25 no.4
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• pp.685-692
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• 2015

In this study, the effects of trees on flow and scalar dispersion in an urban street canyon were investigated using a computational fluid dynamics (CFD) model. For this, we implemented the drag terms of trees to the CFD model, and compared the CFD-simulated results to the wind-tunnel results. For comparison, we considered the same building configuration as the wind-tunnel experiment. The trees were located at the center of street canyon with the aspect ratio (defined as the ratio of the street width to the building height) of 1. First, the flow characteristics were analyzed in the tree-free and high-density tree cases and the results showed that the CFD model reproduced well the flow pattern of the wind-tunnel experiment and reflected the drag effect of trees in the street canyon. Then, the dispersion characteristics of scalar pollutants were investigated for the tree-free, low-density tree and medium-density tree cases. In the tree-free case, the nondimensionalized concentration distribution simulated by the CFD model was quite similar to that in the wind-tunnel experiment in magnitude and pattern. The correlation coefficients between the measured and simulated concentrations are more than 0.9 in all the cases. As the tree density increased, nondimensionalized concentration increased (decreased) near the wall of the upwind (downwind) building, which resulted from the decrease in wind speed case by the drag effect of trees. However, the CFD model underestimated (overestimated) the concentration near the wall of upwind (downwind) building.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.96-102
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• 2008

For centuries now, wind tunnels have been a key element in scientific research in a number of fields. Experimenting with racecars, airplanes, weather patterns, birds, and various other areas has been made much easier because of its development. In the racing field, for example, the information gathered from this testing can mean the difference between winning and losing a race. Weather simulations can also provide valuable information regarding building stability and safety. This has become very important when designing buildings today. Valuable information concerning bird flight has also been collected based on wind tunnel testing. Wind tunnels have a variety of important uses in the world today. Wind tunnel that used here is an open loop low speed wind tunnel. The fundamental principles of this tunnel is moving the air using exhaust fan In the rear side, and placing the cube in the external balance system which used to measure the working force. This experiment is using 50mm cube of finished wood. From this experiment we can get Drag Force (FD), The Reynolds Number (Re) and The Coefficient of Brae (CD).

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.4
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• pp.393-400
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• 2012

This paper deals with a development of 2-DOF flutter experiment equipment which represents a 2-DOF typical section model. For a conventional 2-DOF flutter experiment equipment, it is hard to observe flutter boundary clearly due to the complexity of the experiment equipment. To refine our flutter experiment equipment system, a compliant mechanism based torsional spring is used. Well-designed extruded aluminum pipe works as a torsional spring. SolidWorks and ANSYS are used for modeling, analysis and design of the torsional spring. With this designed torsional spring, the 2-DOF flutter experiment equipment is developed and wind tunnel tests are performed. Clear flutter boundary which is estimated by classical flutter analysis is observed in the experiments.