하천 및 호소 수질모의를 위한 Delft3D-WAQ 적용성 검토

정석일,김수영,이승오,Jeong, Seok-Il,Kim, Su-Yeong,Lee, Seung-O 한국수자원학회 2019 물과 미래(한국수자원학회지) Vol.52 No.10

수리실험을 통한 보 연결부 제방 세굴 특성 분석

정석일,이승오,Jeong, Seok Il,Lee, Seung Oh 한국안전학회 2017 한국안전학회지 Vol.32 No.4

Typical flow regime of overflow at barrier or weir constructed in mid and small streams becomes as the submerged flow during most flood events. One of major causes of barrier failure has been reported as the levee-scour near the conjuction node between barrier and levee. However, most related design guidelines in Korea have not mentioned about the protection of levee around barrier or weir in detail. Furthermore, most previous researches have focused on the flow characteristics of overflow around several types of weirs but they did not have considered the material properties of levee itself. In this study, local scour near barrier was investigated with different material properties of levee under the submerged overflow condition which is assumed to reenact a flood event. Based on results from Fritz et al. and Mavis et al., a theoretical formula was also proposed in initial stage of laboratory experiments. And hydraulic experiments were carried out for the verification of the proposed formula. Levee was installed in the prismetic trapezoidal open channel and most parts were made of concrete except for movable section in which scour was expected to occur for the efficiency of experimental procedure. Each compaction of movable section in levee was followed by the basis of the KS F 2312. Further, after performing the experiments to find the optimum water content for each sediment, the specific amount of water was injected before flowing water. The difference between the proposed theoretical formula and experiment results was not much but considerable, which might be caused by the effect of compaction. For theoretical approach, it seemed that the formula did not take into account the compaction of levee, thus the correction coefficient for levee compaction determined in the literature was considered. Finally, the formula for the length of scour around barrier or weir was proposed, which can be useful to predict a levee in the reference design of revetment in mid and small streams. As shortly future study, scour length of levee around barrier or weir under different flow conditions such as perfect overflow condition will be studied and it will be able to contribute to suggest the design formula or criteria under all overflow conditions near barrier or weir.

급확대 구간에서 준설영향으로 인한 상류 수리특성 변화에 대한 민감도 분석

정석일,류광현,이승오,Jeong, Seok Il,Ryu, Kwang Hyun,Lee, Seung Oh 한국안전학회 2017 한국안전학회지 Vol.32 No.4

Sediment exchange in river has been affected by artificial changes such as dredging and abnormal climate changes like intense rainfall. Over last decades in Korea, there were many constructions, restoration or rehabilitation in rivers. Therefore, deposition and erosion become more actively occurred than before, which may threaten the river safety such as flood defense. For safety's sake, the dredging of river bed, which is considered as the most typical measure, has been increased to extend hydraulic conveyance compared with previous conditions. However, since it might change the sediment mechanism, there would be another risk at which unexpected side effects such as headward erosion could be occurred. Particularly, sedimentation at abrupt expansion region is able to lead to hydraulic characteristics like water elevation in the upstream region in the beginning of dredging, which, however, has been barely studied in this field. Therefore in this study, the relationship between sediment mechanism at dredging section and hydraulic characteristics in upstream region were presented through numerical simulations in the idealized abruptly widen channel using Delft3D. The ideal channel of 2,000 m length with each side angle of 45 degrees at abruptly widen expansion region was employed to consider the sediment angle of repose. The sensitivity analysis was performed on the dimensionless factors consisted of upstream and downstream depths($h_u$, $h_d$), width($w_u$, $w_d$), water level(H), flow rate(Q) and discharge of sediment($Q_s$). And the sedimentation amount at dredging and the upstream hydraulic characteristics were investigated through that analysis. It showed that $h_d/h_u$, $H/h_u$ and $w_d/w_u$ were more influential in sequence of effect on sedimentation amount, while $h_d/h_u$, $w_d/w_u$ and $H/h_u$ on upstream region. It means that $h_d/h_u$ was revealed as the most significant factors on sedimentation, also it would most highly affect the rising of water level upstream.

저층수 배출관을 이용한 보 상류 퇴적유사 배제 능력 검토

정석일(Jeong Seok il),이승오(Lee Seung oh) 대한토목학회 2016 대한토목학회 학술대회 Vol.2016 No.10

고무보 저층수 배출관의 유사 배제 성능 실험 연구

정석일 ( Seok Il Jeong ),이승오 ( Seung Oh Lee ) 한국안전학회(구 한국산업안전학회) 2016 한국안전학회지 Vol.31 No.5

Most small weir installed in Korea is concrete solidated weir. Fixed weir causes stagnant flow, which leads to deposit sediment just upstream of weir. As time goes on, it would induce reduction of water storage capacity and invoke the serious water quality issues. Therefore, there has been a growing interest in movable weir. Especially, the flexible rubber weir is easy to install and possible to operate in extreme environments. However, even though this type can be flatable, it is also not free from sediment deposition problem. Thus, to enhance the ability of releasing deposition the bypass pipe was constructed underneath it. In this study the performance of its ability was examined with hydraulic model test. This bypass pipe was designed with 3 different dimensions to connect between each bottom of upstream and downstream of a weir, such as Type A, B, and C. The efficiency of drainage of deposition upstream was studied under two water of upstream and sediment heights. In addition, the ability of sediment emission through the bypass pipe after the pipe was blocked by debris like soil, vegetation et al. was examined by video monitoring. From this study, it was suggested a dimensionless equation which show the relationship of variable parameters and amount of emission sediment through bypass pipe. And it was found that the most significant factors on efficiency of releasing were elbow angle and discharge, and the ability of emission when the pipe was blocked was most highly influenced in tilting length.

토석류 방재구조물 모의에 대한 Sink Module의 이론적 접근

정석일(Jeong Seok il),송창근(Song Chang geun),이승오(Lee Seung oh) 한국방재학회 2017 한국방재학회논문집 Vol.17 No.6

이상기후로 인한 집중호우의 증가로 토석류에 대한 피해가 급증하고 있다. 토석류의 발생은 사면을 따라 흐르며 다량의 토석과 유목을 발생시키고, 시설물 및 농경지 등을 황폐화 시키는 주요 원인이 된다. 그러나 이와 관련된 국내의 구조적대에 대한 설계 기준 또는 지침은 토석류 발생원인 조사나 토석류의 발생형태별 피해억제를 위한 대책공법 선정 방안에 대해 규정하고 있는 실정이며, 설계를 위한 가이드라인 등의 제시는 부족한 상황이다. 결국 토석류 방재 구조물에 대한 연구는 수치해석을 이용할 수밖에 없는 실정이지만, 이마저도 사방댐 모의에 집중되어 있을 뿐, 맨홀 형태의 구조물에 대한 모의는 2차원 모형으로 재현할 수 없는 상황이다. 이에 본 연구에서는 구조물에 대한 정확한 토석류 해석이 가능한 UDS(Urban Debris Simulator)에 맨홀형 방재구조물을 간접적으로 재현할 수 있는 Sink 모듈을 개발하였다. 경사면에 대한 맨홀 유입량을 이론적으로 제시하였으며, 이를 UDS에 탑재하고, 이를 3차원 유동해석 프로그램 결과와 비교하여 정확도를 검증하였고 적용성을 높이는 방안도 제안하였다. Intensified torrential heavy rain caused by the abnormal climate change has increased to occur catastrophic debris flows. When debris flows along the mountainous slope, a large amount of entrainment composed of soil and debris occurs, which becomes the main cause of devastation of facilities and agricultural lands. However, most domestic design criteria or guidelines about structural countermeasures are relatively insufficient to use as the reference in practical designs. Also, due to the deficiency of such related studies on the disaster prevention structures, it is inevitable to utilized the numerical methods instead. However, most of them are hard to reproduce the complex effect of countermeasure, especially sink types, with the two-dimensional models. In this study, we developed the sink module that can indirectly reproduce the reduction of amount of debris flows by sink type countermeasure in the Urban Debris Simulator (UDS). First, the amount of sink inflow along the hilly slope was theoretically presented. And numerical results were compared with the results from the trustworthy three-dimensional model to verify the accuracy and to advance practical application for debris flow analysis.

새만금 종합개발계획에 따른 새만금 유역 치수 안전성 수치모의

정석일 ( Seok Il Jeong ),유형주 ( Hyung Ju Yoo ),류광현 ( Kwang Hyun Ryu ),이승오 ( Seung Oh Lee ) 한국안전학회(구 한국산업안전학회) 2018 한국안전학회지 Vol.33 No.5

The Saemangeum master plan includes dredging and waterproofing materials, construction projects that can change the hydraulic characteristics of the Saemangeum and Mangyeong and Dongjin River basins. In this study, the river safety of 2030 when the Saemangeum master plan was completed for 100 year frequency, 500 year frequency and 100 year frequency applied RCP 8.5 scenario was examined using Delft3D. As a result of the analysis, it was confirmed that there was no overflowing point at the 100 year frequency, but the difference between the flood level and the river bank elevation was relatively small at the curved and river joint part. At the 100-year frequency with the 500-year frequency and the RCP 8.5 scenario, the possibility of overflowing at several locations was confirmed. The possibility of river bed loss due to fast velocity appears in the upstream part of Mankyung River and it is necessary to monitor the safety of hydraulic structures continuously. In addition, it is expected that the expansion of the area showing the characteristics of the lake due to dredging will affect the sediment mechanism and water quality, so detailed and diverse studies will be needed.

홍수파 선단의 축척효과에 대한 보정계수 산정

정석일(Seok-il Jeong),김수영(Soo young Kim),이승오(Seung Oh Lee) 한국산학기술학회 2016 한국산학기술학회논문지 Vol.17 No.6

최근의 이상기후로 인하여 수공구조물의 안전성이 재고되고 있으며, 이에 따라 수공구조물의 붕괴에 대한 연구가 증가하고 있다. 특히 제방 등 수공구조물의 월류로 인한 붕괴로 발생하는 홍수파 선단의 초기 이동속도는 제내지의 위험성을 예측하고, EAP(Emergency Action Plan) 등을 수립하는 기초자료가 된다. 이러한 선단홍수파의 정확한 예측을 위해 수리실험 이 다수 수행되고 있으나, 많은 연구에서 초기의 홍수파 선단에서 발생하는 표면장력에 의한 축척효과(Scale effect)를 고려하 지 않고 있는 실정이다. 이에 본 연구에서는 계면활성제(surfactant)와 영상 분석 장비를 이용한 표면장력 도출 수리실험 및 급 개폐가 가능한 수조를 이용한 홍수파 전파 실험을 통하여, 계면활성제 농도와 표면장력 관계, 표면장력과 홍수파 전파속도 관계, 표면장력과 Weber Number 관계를 도출하여, 초기 홍수파 선단에서 발생하는 표면장력에 의한 축척효과 보정계수 및 축척효과를 받지 않는 한계조건(critical condition)을 제시하였다. 연구결과 Weber Number가 약 12.2 이하일 경우 보정 계수가 필요한 것으로 나타났으며, 그 이상인 경우 축척효과를 무시할 수 있는 것으로 나타났다. Recently, there has been increasing concern regarding the collapse of hydraulic structures due to abnormal climate conditions. Therefore, numerous studies of the collapse of hydraulic structures have been carried out. In particular, the velocity of the propagation of a flood wave-front is important for predicting the inundation safety and establishing an EAP (Emergency Action Plan). Although many hydraulic tests have been conducted for precise predictions of a flood wave-front, the scale effect from downsizing has not considered. In this study, the relationships between surface tension and the concentration of surfactant, between surface tension and the velocity of flood wave propagation, and between surface tension and the Weber Number were derived through hydraulic tests using a surfactant and image analysis equipment. Based on these relations, the modification factor for the scale effect of the front of flood wave propagation was suggested. The results highlight the necessity of a modification factor when the Weber Number is lower than 12.2, but the scale effect can be ignored when the Weber Number over 12.2.

분포 기여도를 이용한 퍼지 Q-learning

정석일(Seok-Il Jeong),이연정(Yun-Jung Lee) 한국지능시스템학회 2001 한국지능시스템학회논문지 Vol.11 No.5

수치해석을 통한 저층수 배출관의 한계조건 제시

정석일(Jeong, Seok il),이승오(Lee, Seung Oh) 대한토목학회 2017 대한토목학회 학술대회 Vol.2017 No.10