• Photonics industry news
• /
• s.21
• /
• pp.74-79
• /
• 2004

• The Magazine of the IEIE
• /
• v.31 no.4
• /
• pp.31-49
• /
• 2004

현재 국내 인터 넷 상용망은 케이티(KORNET), (주)데이콤(BORANET), (주)온세통신(Shinbiro), 하나로통신(hananet), (주)두루넷(Thrunet), (주)엔터프라이즈 네트웍스(CNGIDC), 에스케이텔레콤(SKSpeedNet), 드림라인(DreamX), (주)파워콤(POWERCOMM)등 78개 업체가 인터넷 서비스를 제공하고 있다. 인터넷 서비스 사업자는 1998년도에 총 ISP수가 25개이고 2001년도 99개였으며, 2003년도에는 78개로 약간 감소 추세인 것으로 보여진다. 전국적인 인터넷 기간망 사업자를 대상으로 인터넷 망 구축기술과 규모, 제공되는 서비스현황 등을 한국전산원이 발간할 2004인터넷백서를 근간으로 하여 알아본다.(중략)

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.24 no.2
• /
• pp.63-77
• /
• 2022

Our aim was to reduce estimation errors of a wind velocity model used as an early warning system for weather risk management in the agricultural sector. The Rural Development Administration (RDA) agricultural weather observation network's wind velocity data and its corresponding estimated data from January to December 2020 were used to calculate linear regression equations (Y = aX + b). In each linear regression, the wind estimation error at 87 points and eight time slots per day (00:00, 03:00, 06:00, 09.00, 12.00, 15.00, 18.00, and 21:00) is the dependent variable (Y), while the estimated wind velocity is the independent variable (X). When the correlation coefficient exceeded 0.5, the regression equation was used as the wind velocity correction equation. In contrast, when the correlation coefficient was less than 0.5, the mean error (ME) at the corresponding points and time slots was substituted as the correction value instead of the regression equation. To enable the use of wind velocity model at a national scale, a distribution map with a grid resolution of 250 m was created. This objective was achieved b y performing a spatial interpolation with an inverse distance weighted (IDW) technique using the regression coefficients (a and b), the correlation coefficient (R), and the ME values for the 87 points and eight time slots. Interpolated grid values for 13 weather observation points in rural areas were then extracted. The wind velocity estimation errors for 13 points from January to December 2019 were corrected and compared with the system's values. After correction, the mean ME of the wind velocities reduced from 0.68 m/s to 0.45 m/s, while the mean RMSE reduced from 1.30 m/s to 1.05 m/s. In conclusion, the system's wind velocities were overestimated across all time slots; however, after the correction model was applied, the overestimation reduced in all time slots, except for 15:00. The ME and RMSE improved b y 33% and 19.2%, respectively. In our system, the warning for wind damage risk to crops is driven by the daily maximum wind speed derived from the daily mean wind speed obtained eight times per day. This approach is expected to reduce false alarms within the context of strong wind risk, by reducing the overestimation of wind velocities.