• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.5
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• pp.965-970
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• 2023

Wind profiler and wind lidar produce a vertical profile of winds in high spatiotemporal resolution in the atmospheric boundary layer. The wind lidar makes the wind vector using DBS (Doppler Beam Swinging) and VAD (Velocity Azimuth Display) methods. The DBS method has the advantage of obtaining a wind profile with a fast scan time. On the other hand, there is a restriction that requires at least two beams including vertical beam, which causes a decrease in the data acquisition rate. The VAD method was improved to produce more wind vector of the wind profiler as well as the wind lidar, which generally uses 5 beams. Fourier series was estimated with the radial velocity by the DBS method and wind vector was determined by setting the azimuth interval and applying the radial velocity by the Fourier series to the VAD method. The wind vectors were retrieved at the altitude where the wind was not calculated by the DBS method, and the results of the two methods were consistent.

• Journal of Environmental Science International
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• v.17 no.6
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• pp.699-709
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• 2008

To understand the development mechanism of the aerosols in the surface boundary layer, the variation in the aerosol number concentration due to the divergence and convergence of the wind fields was investigated. The aerosol number concentration was measured in the size ranges of $0.3{\sim}10.0{\mu}m$ using a laser particle counter(LPC) from 0000 LST on 03 Feb. to 0600 LST on 07 Feb. 2004 at Mokpo in Korea during snowfall. The Velocity Azimuth Display(VAD) technique was used to retrieve the radar wind fields such as the horizontal wind field, divergence, and deformations including the vertical air velocity from a single Doppler radar. As a result, the distribution of the aerosol number concentration is apparently different for particles larger than $1{\mu}m$ during snowfall, and it has a tendency to increase at the beginning of the snowfall. The increase and decrease in the aerosol concentration due to the convergence and divergence of the wind fields corresponded to the particles with diameters greater than $1{\mu}m$. It is found that the fluctuations in the aerosol number concentration are well correlated with the development and dissipation of snowfall radar echoes due to the convergence and divergence of horizontal wind fields near the surface boundary layer in the inland during the snowfall.

• Journal of Environmental Science International
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• v.18 no.3
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• pp.333-343
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• 2009

This study presents the analysis of an atmospheric flow around a single-doppler radar located in a pseudo-site. The use of a doppler radar in meteorological field of wind engineering has become widespread over the last several decades, but it has generally been recognized that the single-Doppler radar yields only one single velocity component - the radial velocity($V_r$) so that some additional hypotheses or simplifications must be necessary to get proper wind forecast. Therefore, in order to get an accurate radial velocity($V_r$) in this study, the existing methods such as VAD(Velocity Azimuth Display) and VARD(Velocity Area Display) are reformulated and applied to match the previous study(Waldteufel and Corbin), which have been an important indicator for retrieving a radar velocity. The results presented in this study include the results from different assessment methods in a peudo-site of different wind fields. Unless the existing method can consider the proper decomposition of radial velocity in the real site, then authors suggest an appropriate curve-fitting to decrease the uncertainty errors by changing a grid adaptation rate or applying a weighting function with respect to the wind angle. It is concluded that provided properly formulated fitting function are used, the wind retrieval from the Doppler radar using VAD and VARD methods can be a viable tool for use in wind engineering problems searching for the wind resources.

• Wind and Structures
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• v.15 no.1
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• pp.65-86
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• 2012

Over the last decade substantial improvements have been made in our ability to observe the tropical cyclone boundary layer. Low-level wind speed maxima have been frequently observed in Global Positioning System dropwindsonde (GPS sonde) profiles. Data from GPS sondes and coastal Doppler radars were employed to evaluate the characteristics of tropical cyclone vertical wind profiles in open ocean conditions and at landfall. Changes to the mean vertical wind profile were observed azimuthally and with decreasing radial distance toward the cyclone center. Wind profiles within the hurricane boundary layer exhibited a logarithmic increase with height up to the depth of the wind maximum.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.99-107
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• 2014

Abruptly occurred obstacles on highway threaten driving safety. Radar draws the attention to the collision avoidance system because it can be fully operational in all weather, and day and night condition. This paper presents the design, implementation and performance test results of pulsed Doppler radar system for detection and warning of road obstacles. The system is designed to consider highway environment and detection capability about various fixed and moving obstacles. The system consists of 4 subsystems, which include antenna unit, transmitter and receiver unit, radar signal & data processing unit, and controller & display unit. The core technologies include clutter map based change detection for fixed obstacles detection, Doppler estimation for velocity detection of moving targets, and azimuth angle estimation method using monopulse for lane estimation and tracking. The design performance of the developed radar system is verified through experiments using a fixed reference target and moving vehicles in test highway.