• Journal of the Korean GEO-environmental Society
• /
• v.24 no.12
• /
• pp.31-38
• /
• 2023

In this study, runoff characteristics analysis was conducted as a basic research to establish a forecasting and warning system for flood risk areas in small mountainous basins in South Korea. The Danyang 1 Bridge basin located in Danyang-gun, Chungcheongbuk-do was selected as the study basin, and the watershed characteristic factors were calculated using Q-GIS based on the digital elevation model (DEM) of the basin. In addition, nine heavy rainfall events were selected from 2020 to 2023 using hydrometeorological data provided by the National Water Resources Management Comprehensive Information System. HEC-HMS rainfall-runoff model was used to analyze the runoff characteristics of small mountainous basins, and rainfall-runoff model simulation was performed by reflecting 9 heavy rainfall events and calculated basin characteristic factors. Based on the rainfall-runoff model, parameter optimization was performed for six heavy rain events with large error rates among the simulated events, and the appropriate parameter range for the Danyang 1 Bridge basin, a small mountainous basin, was calculated to be 0.8 to 3.4. The results of this study will be utilized as foundational data for establishing flood forecasting and warning systems in small mountainous basin, and further research will be conducted to derive the range of parameters according to basin characteristics.

• Journal of the Korean Society of Radiology
• /
• v.18 no.2
• /
• pp.65-71
• /
• 2024

To achieve high resolution and sensitivity of positron emission tomography (PET) for small animals, the detector is constructed using very thin and long scintillation pixels. Due to the structure of these scintillation pixels, spatial resolution deterioration occurs outside the system's field of view. To solve this problem, we designed a detector that could improve spatial resolution by measuring the interaction depth and improve sensitivity by using a quasi-block scintillator. A quasi-block scintillator size of 12.6 mm x 12.6 mm x 3 mm was arranged in four layers, and optical sensors were placed on all sides to collect light generated by the interaction between gamma rays and the scintillator. DETECT2000 simulation was performed to evaluate the performance of the designed detector. Flood images were acquired by generating gamma-ray events at 1 mm intervals from 1.3 mm to 11.3 mm within the scintillator of each layer. The spatial resolution and peak-to-peak distance for each location were measured in an 11 x 11 array of flood images. The average measured spatial resolution was 0.25 mm, and the average distance between peaks was 1.0 mm. Through this, it was confirmed that all locations were separated from each other. In addition, because the light signals of all layers were measured separately from each other, the layer of the scintillator that interacted with the gamma rays could be completely separated. When the designed detector is used as a detector in a PET system for small animals, it is considered that excellent spatial resolution and sensitivity can be achieved and image quality can be improved.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.18 no.4
• /
• pp.348-359
• /
• 2006

The city of Mokpo suffers lowland inundation damages by sea water flooding even without harsh weather like a typhoon, due to the low level urban infrastructure facilities, oceanic environmental changes by constructions of seadike/seawall and sea level rise caused by global warming. This study performs constructing the simulation system which employs the MIKE21 software. And the system is applied to several typhoon- induced surges which had resulted in inundation at Mokpo. Virtual situation of flooding is simulated in case 59 cm of surge height, which had been occurred actually by RUSA(0215), coincides with Approx. H.H.W. Then the water level of 545 cm corresponds to the extreme high water level(544 cm) for 10 year return period after the construction of Geumho seawall. The results show rapid and broad inundation at Inner-Port, requiring additional preparations for flood protections.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.9 no.3
• /
• pp.127-133
• /
• 2009

In this study, dimensionless-cumulative rainfall curves were generated by multivariate Monte Carlo method. For generation of rainfall curve rainfall storms were divided and made into dimensionless type since it was required to remove the spatial and temporal variances as well as differences in rainfall data. The dimensionless rainfall curves were divided into 4 types, and log-ratio method was introduced to overcome the limitations that elements of dimensionless-cumulative rainfall curve should always be more than zero and the sum total should be one. Orthogonal transformation by Johnson system and the constrained non-normal multivariate Monte Carlo simulation were introduced to analyse the rainfall characteristics. The generative technique in stochastic rainfall variation using multivariate Monte Carlo method will contribute to the design and evaluation of hydrosystems and can use the establishment of the flood disaster prevention system.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.198-198
• /
• 2016

The Citarum River Basin is the biggest river basin in West Java Province, Indonesia and it plays strategic roles in providing water for irrigation, domestic and industrial uses, and power generation, besides controlling the flood during rainy season. Flowing through seven major cities makes the river flow and water demand are vulnerable to land use change around the river. The present water resources management has involved the regulator, operator, and users in deciding an appropriate water management plan for the entire basin. The plan includes an operation plan for three reservoirs, construction or maintenance of the river channel, and water allocation for all users along the river. Following this plan, a smaller operation group will execute and evaluates the plan based on the actual flow condition. Recently, a deforestation, environment degradation, river sedimentation, a rapid growth of population and industry, also public health become new issues that should be considered in water basin planning. Facing these arising issues, a new development program named ICWRMIP was established to advance the existing management system. This program includes actions to strengthen institutional collaboration, do the restoration and conservation of the river environment, improve water quality and public health, also advance the water allocation system. At present, the water allocation plan is created annually based on a forecasted flow data and water usage prediction report. Sometimes this method causes a difficulty for the operator when the actual flow condition is not the same as the prediction. Improving existing system, a lot of water allocation studies, including a development of the database and water allocation simulation model have been placed to help stakeholders decide the suitable planning schemes. In the future, this study also tries to contribute in advancing water allocation planning by creating an optimization model which ease stakeholders discover a suitable water allocation plan for individual users.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.11 no.4
• /
• pp.133-144
• /
• 2006

It is investigated using ADCIRC model to find an optimal gate operation in order to maintain target water level of the inner Saemangeum Reservoir. Various developing procedures and river inflows conditions are considered in modeling. For the gate operations, consecutive openings to inflow and outflow, such as once a day, twice a day and once per two days are considered. However water level increases gradually due to river inflows regardless of gate operations. In order to maintain target level 0.0 m, it is recommended to shut down of gate in order to prevent inflows of outer sea water at least once per 6 days for normal riverine inflows and once per 3 days for flood inflows during consecutive operations. Then it is balanced within maximum of ${\pm}0.4m$ of deviations from target level of 0.0 meter.

• Journal of Korean Society of Rural Planning
• /
• v.21 no.2
• /
• pp.33-49
• /
• 2015

The objective of this study was to predict land use change based on the land use change scenarios for the Hwangguji river watershed, South Korea. The land use change scenario was derived from the representative concentration pathways (RCP) 4.5 and 8.5 scenarios. The CLUE (conversion of land use and its effects) model was used to simulate the land use change. The CLUE is the modeling framework to simulate land use change considering empirically quantified relations between land use types and socioeconomic and biophysical driving factors through dynamical modeling. The Hwangguji river watershed, South Korea was selected as study area. Future land use changes in 2040, 2070, and 2100 were analyzed relative to baseline (2010) under the RCP4.5 and 8.5 scenarios. Binary logistic regressions were carried out to identify the relation between land uses and its driving factors. CN (Curve number) and impervious area based on the RCP4.5 and 8.5 scenarios were calculated and analyzed using the results of future land use changes. The land use change simulation of the RCP4.5 scenario resulted that the area of urban was forecast to increase by 12% and the area of forest was estimated to decrease by 16% between 2010 and 2100. The land use change simulation of the RCP8.5 scenario resulted that the area of urban was forecast to increase by 16% and the area of forest was estimated to decrease by 18% between 2010 and 2100. The values of Kappa and multiple resolution procedure were calculated as 0.61 and 74.03%. CN (III) and impervious area were increased by 0-1 and 0-8% from 2010 to 2100, respectively. The study findings may provide a useful tool for estimating the future land use change, which is an important factor for the future extreme flood.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.59 no.2
• /
• pp.69-79
• /
• 2017

In this study, we developed real-time urban stream discharge forecasting model using short-term rainfall forecasts data simulated by a regional climate model (RCM). The National Centers for Environmental Prediction (NCEP) Climate Forecasting System (CFS) data was used as a boundary condition for the RCM, namely the Global/Regional Integrated Model System(GRIMs)-Regional Model Program (RMP). In addition, we make ensemble (ESB) forecast with different lead time from 1-day to 3-day and its accuracy was validated through temporal correlation coefficient (TCC). The simulated rainfall is compared to observed data, which are automatic weather stations (AWS) data and Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA 3B43; 3 hourly rainfall with $0.25^{\circ}{\times}0.25^{\circ}$ resolution) data over midland of Korea in July 26-29, 2011. Moreover, we evaluated urban rainfall-runoff relationship using Storm Water Management Model (SWMM). Several statistical measures (e.g., percent error of peak, precent error of volume, and time of peak) are used to validate the rainfall-runoff model's performance. The correlation coefficient (CC) and the Nash-Sutcliffe efficiency (NSE) are evaluated. The result shows that the high correlation was lead time (LT) 33-hour, LT 27-hour, and ESB forecasts, and the NSE shows positive values in LT 33-hour, and ESB forecasts. Through this study, it can be expected to utilizing the real-time urban flood alert using short-term weather forecast.

• Korean Journal of Remote Sensing
• /
• v.31 no.2
• /
• pp.183-191
• /
• 2015

If the damage analysis on river-side facilities such as dam, river bank structures and bridges caused by disasters such as typhoon, flood, etc. becomes available, it can be a great help for disaster recovery and decision-making. In this research, We tried to extract a Digital Surface Model (DSM) and analyze the accuracy from Unmanned Air Vehicle (UAV) images on river-side facilities. We tried to apply stereo image-based matching technique, then extracted match results were united with one mosaic DSM. The accuracy was verified compared with a DSM derived from LIDAR data. Overall accuracy was around 3m of absolute and root mean square error. As an analysis result, we confirmed that exterior orientation parameters exerted an influence to DSM accuracy. For more accurate DSM generation, accurate EO parameters are necessary and effective interpolation and post process technique needs to be developed. And the damage analysis simulation with DSM has to be performed in the future.

• Journal of Korean Society on Water Environment
• /
• v.27 no.4
• /
• pp.445-460
• /
• 2011

The objective of this study was to construct and assess the applicability of the EFDC model for Saemangeum Reservoir as a 3D hydrodynamic and water quality modeling tool that is necessary for the effective management of water quality and establishment of conservation measures. The model grids for both reservoir system only and reservoir-ocean system were created using the most recent survey data to compare the effects of different downstream boundary conditions. The model was applied for the simulations of temperature, salinity, water quality variables including chemical oxygen demand (COD), chlorophyll-a (Chl-a), phosphorus and nitrogen species and algal biomass, and validated using the field data obtained in 2008. Although the model reasonably represented the temporal and spatial variations of the state variables in the reservoir with limited boundary forcing data, the salinity level was underestimated in the middle and upstream of the reservoir when the flow data were used at downstream boundaries; Sinsi and Garyuk Gates. In turn, the error caused to increase the bias of water quality simulations, and inaccurate simulation of density flow regime of river inflow during flood events. It is likely because of the loss of momentum of sea water intrusion at downstream boundaries. In contrast to flow boundary conditions, the mixing between sea water and freshwater was well reproduced when open water boundary condition was applied. Thus, it is required to improve the downstream boundary conditions that can accommodate the real operations of the sluice gates.