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2016 Vol.49, Issue 6 Preview Page
Development of a real-time surface image velocimeter using an android smartphone

스마트폰을 이용한 실시간 표면영상유속계 개발

Kwonkyu Yua*
,
Jeong-Geun Hwanga
류 권규a*
,
황 정근a
aDept. of Civil Engrg., Dong-eui University
a동의대학교 공과대학 토목공학과
*교신저자. *Corresponding Author. 
30 June 2016. pp. 469-480
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Abstract

LISFLOOD-FP model in which channel flows are resolved separately from the floodplain flows using either a kinematic or diffusive wave approximation has been used to analyze flooding behavior on the lower Mankyung River influenced by backwater. A calibration and validation process was applied using the previous flood events to assess the model performance. Sensitivity analysis was conducted for main calibrated parameters, such as Manning roughness coefficient and downstream boundary condition. Also, we examined the effect of warm-up for the initial conditions. The results show that the computed hydrograph is in good agreement with measured data on the study reach, even though it was a hydrologic kinematic wave model. The sensitive analysis show that the difference between the computed results may be greater depending on the used calibrated parameters and that the sufficient calibration/validation process against various flood events is necessary. If the flood inundation simulation is performed using the validated model, it is expected to be able to contribute about river planning and policy decision-making for flood damage reduction.

Keywords
velocity measurement
surface image velocimeter
image processing
smartphone
Android

본 연구는 안드로이드 기반의 스마트폰을 이용한 실시간 표면영상유속계를 개발하는 것이다. 스마트폰이 내장한 카메라, GPS, 방향 센서, CPU를 활용하여, 실시간으로 현장에서 하천의 표면유속을 측정하는 것이다. 먼저, 스마트폰의 GPS를 이용하여 측정 현장의 위치를 파악하고, 경사계(방향 센서)를 활용하여 카메라와 촬영면의 기하적인 관계를 설정한다. 이 때 입력해야 할 유일한 변수는 수면과 카메라의 연직 높이뿐이다. 내장된 카메라로 정해진 시간만큼 동영상을 촬영한다. 촬영된 동영상을 개방 소스의 영상처리 라이브러리인 OpenCV를 이용하여 프레임별로 분할하고, 이를 시공간 영상 분석하여 하천 표면의 2차원 유속장을 추정한다. 시판되는 안드로이드 스마트폰에 적용하여 현장 시험한 결과 약 11초에 1회의 순간유속 측정 (1초간의 평균유속 측정)을 할 수 있어, 현장에서 즉각적으로 하천 수표면의 표면유속을 측정할 수 있었다. 또한 이 순간유속을 수십회 반복한 뒤 평균하여 시간평균유속을 구할 수 있었다. 개발된 시스템을 실험 수로에서 시험한 결과, 측정이 매우 효과적이며 편리하였다. 측정된 결과를 프로펠러 유속계에 의한 측정값과 비교한 결과, 최대 오차 13.9%, 평균적으로 10 % 이내의 오차로 실험 수로의 표면 유속을 측정할 수 있었다.

키워드
유속측정
표면영상유속계
영상처리
스마트폰
안드로이드
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Information
  • Publisher :KOREA WATER RESOURECES ASSOCIATION
  • Publisher(Ko) :한국수자원학회
  • Journal Title :Journal of Korea Water Resources Association
  • Journal Title(Ko) :한국수자원학회 논문집
  • Volume : 49
  • No :6
  • Pages :469-480
  • Received Date : 2016-02-22
  • Revised Date : 2016-03-18
  • Accepted Date : 2016-03-21
  • DOI :https://doi.org/10.3741/JKWRA.2016.49.6.469
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