This study, examines the flow characteristics of upstream channel depending on water gate operation of Nakdan Multi-fuctional weir. The specific purpose of this study are to simulate the variation of flow velocity depending on the operation of the weir using 1-dimensional hydraulic model, HEC-RAS, and compare it with observed velocity. For discharge conditions from 50 ㎥/s to 3,500 ㎥/s, it is observed that the velocity of upstream channel is almost constant, whereas for probability flood discharge, the velocity and froude number are increased as the discharge values are increased. The velocity values for downstream boundary condition EL, 40.0 m are more decreased than those for EL. 40.5m. From comparison on the variation of water stage depending on water gate operation, it is observed that the stage values are almost constant for discharges below 300 ㎥/s, whereas 5 cm to 20 cm for discharges over 700 ㎥/s. Flow velocity at streamflow gauging station. Nakdong, is decreased by more than 875% after installing the weir. The results obtained from this study indicate that the velocity of upstream channel is decreased and the discharge and velocity of downstream channel are significantly varied after installing the weir.

Abstract
 1. 서 론
 2. 자료 및 방법
  2.1. 대상유역의 개요
  2.2. 분석방법
 3. 결과 및 고찰
  3.1. 분석결과
  3.2. 분석결과 비교
 4. 결 론
 REFERENCES

• 문상철(경일대학교 건설공학부, School of Construction Engineering, Kyungil University) | Sang-Chul Moon
• 박기범(경일대학교 건설공학부, School of Construction Engineering, Kyungil University) | Ki Bum Park Corresponding author
• 안승섭(경일대학교 건설공학부, School of Construction Engineering, Kyungil University) | Seung-Seop Ahn