This study is daytime and nighttime runoff image data caused by heavy rain on May 27, 2013 at Oedo Water Treatment Plant of Oedo-Stream, Jeju to compute runoff by applying Surface image velocimeter (SIV) and analyzing correlation according to current. At the same time, current was comparatively analyzed using ADCP observation data and fixed electromagnetic surface current meter (Kalesto) observed at the runoff site.
As a result of comparison on resolutions of daytime and nighttime runoff images collected, correlation coefficient corresponding to the range of 0.6~0.7 was 6.8% higher for nighttime runoff image compared to daytime runoff image. On the contrary, correlation coefficient corresponding to the range of 0.9~1.0 was 17% lower. This result implies that nighttime runoff image has lower image quality than daytime runoff image. In the process of computing current using SIV, a rational filtering process for correlation coefficient is needed according to images obtained.

Abstract
 1. 서 론
 2. 상관계수 결정원리
 3. 연구방법
  3.1. 대상하천
  3.2. 관측자료
 4. 결과 및 고찰
  4.1. 주간 영상을 이용한 유속 산정
  4.2. 야간 영상을 이용한 유속 산정
 5. 결 론
 REFERENCE

• 김용석(제주대학교 토목공학과) | Yong-Seok Kim (Department of Civil Engineering, Jeju National University)
• 양성기(제주대학교 토목공학과) | Sung-Kee Yang (Department of Civil Engineering, Jeju National University) Corresponding author
• 김동수(단국대학교 토목환경공학과) | Dong-su Kim (Department of Civil & Env. Engineering, Dankook University)
• 김서준(단국대학교 토목환경공학과) | Seojun Kim (Department of Civil & Env. Engineering, Dankook University)