LSIV를 이용한 하천 합류부 수리 모형 실험

고석현,류권규,윤병만,Koh,Seok-Hyun,Yu,Kwon-Kyu,Yoon,Byung-Man 한국방재학회 2005 한국방재학회논문집 Vol.5 No.1

영상 해석을 이용한 유속 측정 방법인 LSIV를 합류점의 수리 모형 실험에 적용하였다. LSIV에 의해 측정된 표면 유속은 유속계에 의해 측정된 평균 유속과 상당히 유사한 결과를 나타내었다. 일반적인 유속계는 순간적인 지점 유속만을 나타내기 때문에 전체적인 유속장을 살피는 데 어려움이 있으나, LSIV는 전체적인 흐름장의 양상을 한 눈에 살펴 볼 수 있는 좋은 도구이다. 특히 합류점이나 교각 주변부와 같이 흐름이 국부적으로 변화가 심한 경우 LSIV는 적절한 실험 도구가 될 수 있을 것이다. LSIV (Large Scale Image Velocimetry), a technique of image analysis on velocity measurement, was applied to a hydraulic model experiment of river confluence. The surface velocities measured by using LSIV showed similar results with the mean velocities by using a traditional velocimeter, While a general velocimeter can measure only local point velocity, LSIV can measure whole velocity field with one shot. When it is applied to river confluence or around a bridge pier where local flow is dominant, LSIV may be a powerful tool to measure velocity field.

표면영상유속계(SIV)를 이용한 현장유량측정

김서준,주용우,류권규,윤병만,Kim. Seo-Joon,Joo. Yong-Woo,Yu. Kwon-Kyu,Yoon. Byung-Man 한국방재학회 2008 한국방재학회 학술발표대회논문집 Vol.2008 No.1

표면영상유속계(SIV)는 기존의 입자영상유속계(PIV)의 원리를 이용하여 하천의 표면유속을 측정하는 방법이다. 본 연구에서는 경제적이고 효율적인 유속측정 기법인 SIV 기법을 이용하여 국내 3개 하천에 대하여 현장 유량측정에 적용하였다. 현장 영상분석은 다중카메라 방식을 이용하였고 영상분석과정에 필요한 참조점과 횡단면 자료는 측량을 통하여 획득하였다. SIV로 측정된 유속을 검증하는 수로 실험의 결과, 평균오차 10% 이내의 정확도를 보여 정확한 유속측정이 가능함을 확인하였다. 그러나, 실제 하천에의 적용에서는 저수위시와 악천후시에 대해서는 20 % 이내의 오차를 보이는 것으로 나타났다. 향후 SIV 기법의 문제점들을 해결한다면 언제 어디서나 효율적이고 경제적인 유량측정을 할 수 있을 것이다. 그리고 이를 활용하여 실시간 하천정보시스템으로 발전시킴으로써 하천 관리에 큰 도움이 될 것이라 판단된다. Surface Image Velocity (SIV) is a technique which measures the surface velocity of river by using the principle of Paticle Image Velocimetry (PIV). The technique is economical and efficient way to measure velocity in rivers. The present paper aims to apply the technique to three rivers in Korea. It uses pairs of river surface images taken with two digital-cameras and reference points and cross section data which were acquired through plane survey. The performance of SIV was verified with automatic cart on an experimental flume. The test revealed that average error was less than 10 %, which assures that SIV can be used to measure velocity accurately. When it was applied to rivers with low water levels or rough weather condition, however, it showed the error about 20 %. If the problems of SIV technique are settled down, it can be one of the most convenient and economical ways to measure water discharge anytime and anywhere. And then it would be helpful to river management as developing a real-time river information system.

자갈 및 암반 하상 산지하천의 고리형 수위-유량 관계 분석

김동수,양성기,류권규,Kim, Dong-Su,Yang, Sung-Kee,Yu, Kwon-Kyu 한국수자원학회 2012 한국수자원학회논문집 Vol.45 No.9

홍수 발생 시 모래하천의 수위-유량 관계가 고리형을 이룬다는 것은 많은 현장 계측을 통해 보고되어 왔다. 또한, 홍수파 해석이나 사련에서 사구로 변동되는 하상해석을 통해 고리형 수위-유량 관계의 원인이 규명되어서 고리의 형태나 진행방향 등에 대해서는 이론적으로도 상당부분 입증되어 있다. 그러나 경사가 급한 자갈 및 암반으로 구성된 산지하천의 경우, 현장유량계측의 어려움과 관측 정확도의 문제로 고리형 수위-유량 관계에 대한 연구가 매우 드물었다. 본 논문은 자갈 및 암반지형의 산지하천인 제주도 한천에서 2011년 태풍 무이파 때 계측한 홍수 유량을 바탕으로 수위-유량 관계를 구축하고, 자갈하천에서 형성되는 고리형 수위-유량곡선을 분석하고자 한다. 유량계측 방식으로는 홍수기에 적합한 비접촉식인 전자파 표면유속계를 사용하여, 홍수의 상승기와 하강기의 유량을 시간 단위로 계측하는 데 성공했다. 계측결과 수위-유량관계에서 뚜렷한 고리 형상을 확인할 수 있었다. 그리고 고리의 이력이 모래하천과 정반대로 동일수위에서 상승기의 유량이 하강기의 유량보다 작은, 고리 경로의 역전 현상을 발견하였다. 이러한 역전현상은 자갈하천의 조도의 변화가 모래하천의 경우와 반대로 발생하는 데 기인하는 것으로 추정한다. It is well-known that loop effect of the stage-discharge relationship is formulated based on many field observations especially for the sand rivers. Theoretical understandings of the loop effect for the sand rivers have been widely provided, based on the facts that it is driven by the flood wave propagation and bed form changes over the given flood period. However, very few theoretical studies or field observations associated with loop-rating curves in the gravel or rock-bed mountain streams have been attempted so far, due particularly to the difficulties in the accurate discharge measurement during the flood in such field conditions. The present paper aims to report a unique loop-rating curve measured at a gravel and rock-bed mountain stream based on the flood discharge observation acquired during the typhoon, Muifa that passed nearby Jeju Island in summer of 2011. As velocity instrumentation, a non-intrusive Surface Velocity Doppler Radar to be suitable for the flood discharge measurement was utilized, and discharges were consecutively measured for every hour. Interestingly, the authors found that the hysteresis of the loop-rating curve was adverse compared to the typical trend of the sand bed streams, which means that the discharge of the rising limb is smaller than the falling limb at the same stage. We carefully speculate that the adverse trend of the loop-rating curve in the gravel bed was caused by the bed resistance change that works differently from the sand bed case.

SWAT 및 HEC-RAS모형을 활용한 유역 내 토사수지분석기법

김대곤,정태성,류권규,Kim. Dae Gon,Cheong. Tae Sung,Yu. Kwon Kyu 한국방재학회 2012 한국방재학회논문집 Vol.12 No.6

하천내에서 각종 사업을 시행하면, 그로 인해 하천에서는 토사유출, 하상 저하에 따른 인공 구조물의 기초부 손상, 댐 저수지에서의 퇴적, 해안 침식 등과 같은 토사이동에 관련된 문제가 발생하게 된다. 이러한 토사의 유출-거동을 종합적으로 파악하는 것이 토사수지분석이다. 본 연구는 유역유출 모형과 하상변동 예측 모형을 이용하여 토사수지분석을 위한 새로운 방법을 제안하였다. 낙동강 주요 지류 중 하나이며 영주댐 건설이 계획된 대표적인 충적하천유역인 내성천에 모형을 적용하고 모형의 검정과 적용성 검토를 수행하였다. 모의결과 모형은 자연하천에서의 토사유출-거동을 잘 재현하는 것으로 나타났다. 특히, 모형은 내성천에서 실측한 유사량과 유사한 계산결과를 보이는 것으로 나타났다. 내성천 유역의 토사수지 분석결과 총 1,704만톤의 토사손실이 발생한 것으로 나타났으며 이들은 대부분 하도침식에 의한 것으로 추정된다. 제안된 방법은 자연하천에서 토사수지분석이나 토사이동 관련 재해위험도저감에 활용될 수 있을 것이다. Various river projects have caused sediment transport relate problems such as sediment yields, foundation damages of river facilities by riverbed degradation, siltation on reservoir and erosion in coast. To understand comprehensively these behaviors related on sediment erosion, transport and yields from inflows to outflows in river watershed, usually, the sediment budget analysis is used. This study propose a new sediment budget analysis method using both sediment transport models of the watershed runoff model and riverbed fluctuation model. To calibrate and validate the model, the method is applied in the Naeseong-cheon which typical alluvial river is one of the main tributaries of the Nakdong river and Yeong-ju dam is planned to be built. The results show that proposed sediment budget analysis method represents well sediment transports in the natural river watershed. Specifically, sediment loads calculated by the method is fit well to the measured sediment loads in the Naeseong-cheon watershed. The sediment budget analysis results show that the soil loss of 17,040,000 tons due to erosion in many parts of river bed is estimated in the Naeseong-cheon. The suggested method can be used for sediment budget analysis and sediment related disaster risk reduction in the natural streams.

연구논문 : 전자파와 수표면 영상을 이용한 산지하천 홍수유량 및 유속 계측 비교 연구

양성기 ( Sung Kee Yang ),김동수 ( Dong Su Kim ),류권규 ( Kwon Kyu Yu ),강명수 ( Myeong Su Kang ),정우열 ( Woo Yul Jung ),이준호 ( Jun Ho Lee ),김용석 ( Yong Seok Kim ),유호준 ( Ho Jun You ) 한국환경과학회 2012 한국환경과학회지 Vol.21 No.6

Due to the difficulties for measuring flood discharge in the dangerous field conditions, conventional instruments with relatively low accuracy such as float still have been widely utilized for the field survey. It is also limited to use simple stage-discharge relationship for assessment of the flood discharge, since the stage-discharge relationship during the flood becomes complicated loop shape. In recent years, various non-intrusive velocity measurement techniques such as electromagnetic wave or surface images have been developed, which is quite adequate for the flood discharge measurements. However, these new non-intrusive techniques have little tested in the flood condition, though they promised efficiency and accuracy. Throughout the field observations, we evaluated the validity of these techniques by comparing discharge and velocity measurements acquired concurrently during the flood in a mountain stream. As a result, the flood discharge measurements between electromagnetic wave and surface image processing techniques showed high positive relationship, but velocities did not matched very well particularly for the high current speed more 3 m/s. Therefore, it should be noted here that special cares are required when the velocity measurements by those two different techniques are used, for instance, for the validation of the numerical models. In addition, authors assured that, for the more accurate flood discharge measurements, velocity observation as well as stage height is strongly necessary owing that the unsteady flow occurs during the flood.

표면영상유속계(SIV)를 활용한 홍수유출량 산정 시 주,야간영상의 정확도 비교분석

김용석 ( Yong Seok Kim ),양성기 ( Sung Kee Yang ),류권규 ( Kwon Kyu Yu ),김동수 ( Dong Su Kim ) 한국환경과학회 2015 한국환경과학회지 Vol.24 No.4

This study analyzed the velocimetry of runoff and measured the flood discharge by applying the SIV (Surface Image Velocimetrer) to the daytime and nighttime flow image data with special reference to Seong-eup Bridge at Cheonmi stream of Jeju during the flow by the severe rainstorm on May 27, 2013. A 1000W lighting apparatus with more than 150 lux was installed in order to collect proper nighttime flow image applied to the SIV. Its value was compared and analyzed with the velocity value of the fixed electromagnetic wave surface velocimetry (Kalesto) at the same point to check the accuracy and applicability of the measured velocity of flow. As a result, determination coefficient R2 values were 0.891 and 0.848 respectively in line with the velocity distribution of the daytime and nighttime image and the flow volume measured with Kalesto was approximately 18.2% larger than the value measured with the SIV.

재난감시용 하천 CCTV를 활용한 홍수유출량 산정

김용석 ( Yong Seok Kim ),양성기 ( Sung Kee Yang ),류권규 ( Kwon Kyu Yu ),김동수 ( Dong Su Kim ) 한국환경과학회 2014 한국환경과학회지 Vol.23 No.4

The present study aims to apply a surface image velocimetry(SIV) system to video images captured with CCTV and estimate the flood discharge. The CCTV was installed at the Hancheon Bridge of the Han Cheon in Jeju Island for disaster surveillance, and seven flood events occurred in 2012 were used. During the image analyses, input parameters, interrogation areas and searching areas were determined with proper calibration procedures. To check for accuracy and applicability of SIV, the velocities and flood discharges estimated by SIV were compared with the measured ones by an electromagnetic surface velocimeter, Kalisto. The comparison results showed fairly good agreements. The RMSE(Root Mean Square Error) values between two instruments showed a range of 4.13 and 14.2, and the determination coefficients reached 0.75 through 0.85. It means that the SIV could be used as a good alternative method for other traditional velocity measuring instruments in measuring flood discharges.

SWAT 및 HEC-RAS 모형을 결합한 내성천 유역의 토사수지분석

김대곤(Kim Dae Gon),양문용(Yang Moon Yong),하성원(Ha Sung Won),류권규(Yu Kwon Kyu) 대한토목학회 2010 대한토목학회 학술대회 Vol.2010 No.10

태양광 밝기 변화에 따른 표면영상유속계의 유속 측정 불확도 산정

임윤성(Im, Yun Seong),윤병만(Yoon, Byung Man),류권규(Yu, Kwon Kyu),김서준(Kim, Seo Jun) 대한토목학회 2022 대한토목학회 학술대회 Vol.2022 No.10

다양한 첨단 유량 계측기기를 활용한 제주도 하천 유출 비교 분석

양성기 ( Sung Kee Yang ),김동수 ( Dong Su Kim ),정우열 ( Woo Yul Jung ),류권규 ( Kwon Kyu Yu ) 한국환경과학회 2011 한국환경과학회지 Vol.20 No.6

Different from the main land of South Korea, Jeju Island has been in difficulties for measuring discharge. Due to high infiltration rate, most of streams in Jeju Island are usually in the dried state except six streams with the steady base flow, and the unique geological characteristics such as steep slope and short traveling distance of runoff have forced rainfall runoff usually to occur during very short period of time like one or two days. While discharge observations in Jeju Island have been conducted only for 16 sites with fixed electromagnetic surface velocimetry, effective analysis and validation of observed discharge data and operation of the monitoring sites still have been limited due to very few professions to maintain such jobs. This research is sponsored by Ministry of Land, Transport and Maritime Affairs to build water cycle monitoring and management system of Jeju Island. Specifically, the research focuses on optimizing discharge measurement techniques adjusted for Jeju Island, expanding the monitoring sites, and validating the existing discharge data. First of all, we attempted to conduct discharge measurements in streams with steady base flow, by utilizing various recent discharge monitoring techniques, such as ADCP, LSPIV, Magnetic Velocimetry, and Electromagnetic Wave Surface Velocimetry. ADCP has been known to be the most accurate in terms of discharge measurement compared with other techniques, thus that the discharge measurement taken by ADCP could be used as a benchmark data for validation of others. However, there are still concerns of using ADCP in flood seasons; thereby LSPIV would be able to be applied for replacing ADCP in such flooded situation in the stream. In addition, sort of practical approaches such as Magnetic Velocimetry, and Electromagnetic Wave Surface Velocimetry would also be validated, which usually measure velocity in the designated parts of stream and assume the measured velocity to be representative for whole cross-section or profile at any specified location. The result of the comparison and analysis will be used for correcting existing discharge measurement by Electromagnetic Wave Surface Velocimetry and finding the most optimized discharge techniques in the future.