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.

선행강우를 고려한 제주하천 유출특성 분석

양성기 ( Sung Kee Yang ),김동수 ( Dong Su Kim ),정우열 ( Woo Yul Jung ) 한국환경과학회 2014 한국환경과학회지 Vol.23 No.4

The rainfall-runoff characteristics in Jeju Island significantly differ from those in inland, due to highly permeable geologic features driven by volcanic island. Streams are usually sustained in the dry conditions and thereby the rainfall-runoff characteristics changes in terms of initiating stream discharge and its types, depending highly on the antecedent precipitation. Among various the rainfall-runoff characteristics, lag time mainly used for flood warning system in river and direct runoff ratio for determining water budget to estimate groundwater recharge quantity are practically crucial. They are expected to vary accordingly with the given antecedent precipitation. This study assessed the lag time in the measured hydrograph and direct runoff ratio, which are especially in the upstream watershed having the outlet as 2nd Dongsan bridge of Han stream, Jeju, based upon several typhoon events such as Khanun, Bolaven, Tembin, Sanba as well as a specific heavy rainfall event in August 23, 2012. As results, considering that the lag time changed a bit over the rainfall events, the averaged lag time without antecedent precipitation was around 1.5 hour, but it became increased with antecedent precipitation. Though the direct run-off ratio showed similar percentages (i.e., 23%) without antecedent precipitation, it was substantially increased up to around 45% when antecedent precipitation existed. In addition, the direct run-off ration without antecedent precipitation was also very high (43.8%), especially when there was extremely heavy rainfall event in the more than five hundreds return period such as typhoon Sanba.

연구논문 : 제주도 지하수관정의 오염저감방안

양성기 ( Sung Kee Yang ),한상철 ( Sang Cheol Han ) 한국환경과학회 2007 한국환경과학회지 Vol.16 No.6

제주도 연안해역의 폭풍해일고 산정

양성기 ( Sung Kee Yang ),김상봉 ( Sang Bong Kim ) 한국환경과학회 2014 한국환경과학회지 Vol.23 No.3

Storm surge height in the coastal area of Jeju Island was examined using the Princeton Ocean Model(POM) with a sigma coordinate system. Amongst the typhoons that had affected to Jeju Island for six years(1987 to 2003), the eight typhoons(Maemi, Rusa, Prapiroon, Olga, Yanni, Janis, Gladys and Thelma) were found to bring relatively huge damage . The storm surge height of these typhoons simulated in Jeju harbour and Seogwipo harbour corresponded relatively well with the observed value. The occurrence time of the storm surge height was different, but mostly, it was a little later than the observed time. Jeju harbour showed a higher storm surge height than Seogwipo harbour, and the storm surge height didn`t exceed 1m in both of Jeju harbour and Seogwipo harbour. Maemi out of the eight typhoons showed the maximum storm surge height(77.97 cm) in Jeju harbour, and Janis showed the lowest storm surge height(5.3 cm) in Seogwipo harbour.

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.

한천유역의 수문학적 특성을 고려한 관측자료 기반 홍수량 산정

양성기 ( Sung-kee Yang ),김민철 ( Min-chul Kim ),강보성 ( Bo-seong Kang ),김용석 ( Yong-seok Kim ),강명수 ( Myung-soo Kang ) 한국환경과학회 2017 한국환경과학회지 Vol.26 No.12

This study reviewed the applicability of the existing flood discharge calculation method on Jeju Island Han Stream and compared this method with observation results by improving the mediating variables for the Han Stream. The results were as follows. First, when the rain-discharge status of the Han Stream was analyzed using the flood discharge calculation method of the existing design (2012), the result was smaller than the observed flood discharge and the flood hydrograph differed. The result of the flood discharge calculation corrected for the curve number based on the terrain gradient showed an improvement of 1.47 - 6.47% from the existing flood discharge, and flood discharge was improved by 4.39 - 16.67% after applying the new reached time. In addition, the sub-basin was set separately to calculate the flood discharge, which yielded an improvement of 9.92 - 32.96% from the existing method. In particular, the steepness and rainfall-discharge characteristics of Han Stream were considered in the reaching time, and the sub-basin was separated to calculate the flood discharge, which resulted in an error rate of -8.77 to 8.71%, showing a large improvement of 7.31 - 28.79% from the existing method. The flood hydrograph also showed a similar tendency.

태풍 차바로 인한 제주도 홍수피해와 대책

양성기(Sung-Kee Yang),이준호(Jun-Ho Lee),강보성(Bo-Seong Kang) 대한토목학회 2017 대한토목학회지 Vol.65 No.1

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.

지하수 모델을 이용한 제주도 지하수 유동특성 및 수리전도도 분석

김민철,양성기,Kim, Min-Chul,Yang, Sung-Kee 한국환경과학회 2019 한국환경과학회지 Vol.28 No.12

We used numerical models to reliably analyze the groundwater flow and hydraulic conductivity on Jeju Island. To increase reliability, improvements were made to model application factors such as hydraulic watershed classification, groundwater recharge calculation by precipitation, hydraulic conduction calculation using the pilot point method, and expansion of the observed groundwater level. Analysis of groundwater flow showed that the model-calculated water level was similar to the observed value. However, the Seogwi and West Jeju watersheds showed large differences in groundwater level. These areas need to be analyzed by segmenting the distribution of the hydraulic conductivity. Analyzing the groundwater flow in a sub watershed showed that groundwater flow was similar to values from equipotential lines; therefore, the reliability of the analysis results could be improved. Estimation of hydraulic conductivity distribution according to the results of the groundwater flow simulation for all areas of Jeju Island showed hydraulic conductivity > 100 m/d in the coastal area and 1 - 45 m/d in the upstream area. Notably, hydraulic conductivity was 500 m/d or above in the lowlands of the eastern area, and it was relatively high in some northern and southern areas. Such characteristics were found to be related to distribution of the equipotential lines and type of groundwater occurrence.

Landsat-7 ETM+ 영상을 이용한 제주 주변 해역의 해저 용출수 분포 지역 추정 연구

박재문,김대현,양성기,윤홍주,Park, Jae-Moon,Kim, Dae-Hyun,Yang, Sung-Kee,Yoon, Hong-Joo 한국전자통신학회 2014 한국전자통신학회 논문지 Vol.9 No.7

본 논문은 Landsat-7 ETM+ 영상의 열적외 밴드를 이용하여 제주도 주변 해역의 해수면 온도 분포 영상을 제작하여 해저 용출수를 탐지하고자 하였다. 해수면 온도 분포 영상을 제작하기 위해 온도변환 알고리즘을 이용하여 위성영상의 DN 값을 온도 값으로 변환하여 해수면 온도 분포를 분석하였다. 해저 용출수 예상 지역 추정은 해수면 온도 분포 영상에서 해저 용출수의 온도로 판단되는 $15{\sim}17^{\circ}C$ 범위를 추출하는 것인데, 계절적으로 해수면 평균 온도와 해저 용출수 온도의 차가 많이 발생하는 여름철 영상(2006년 7월 28일과 2006년 8월 29일, 2008년 9월 19일)을 이용하였다. 그 결과 제주도의 동북부 연안에서 해저 용출수로 추정되는 지역이 일부 나타났다. This study was aimed to detect Submarine Groundwater Discharge (SGD) distribution image of Sea Surface Temperature (SST) using infrared band of Landsat-7 ETM+ around Jeju island. It is used to analyze SST distribution that DN value of satellite images converted into temperature. The estimation of SGD location is that extracting range of $15{\sim}17^{\circ}C$ from SST. The summer season images(July 28. 2006, Aug. 29. 2006 and Sep. 19. 2008) were used to analyze big difference between SST and temperature of SGD. The results, estimated SGD locations were occurred part of coastal area in northeastern of Jeju island.