For the feasibility study of a wind energy site, accurate information on the flow field within the given full-scale site is a prerequisite. Two 2-D ultrasonic anemometers and one cup anemometer, located perpendicular to the prevailing wind direction, were used to measure the mean and instantaneous wind velocities at a height of 4.5 m. The experiments showed that the Reynolds number was about 6.7 x 10(5) (based on the sensor height and the wind velocity) and the friction velocity, u(*) about 0.32 ms(-1). The power-spectrum analysis on horizontal and vertical wind speed was conducted over a wide range of frequencies by joining together various portions of the spectrum. There appeared to be four major eddy-energy peaks in the spectrum; each peak occurred at periods of about 1 or 2 min, 8 h, 24 h and 100 h. Between the peaks, a broad spectral gap was centered at a frequency ranging from 0.2 to 10 cycles per hour. On the basis of an overall analysis of the short-term data measured in Wol-Ryong, Jeju Island, it is concluded that for the development of future wind energy resources, the Wol-Ryong site is a good candidate for a future wind energy site. (C) 2010 Elsevier Ltd. All rights reserved.