• Journal of Korea Water Resources Association
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• v.56 no.12
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• pp.981-992
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• 2023

Due to recent global climate change, the scale of flood damage is increasing as rainfall is concentrated and its intensity increases. Rain on a scale that has not been observed in the past may fall, and long-term rainy seasons that have not been recorded may occur. These damages are also concentrated in ASEAN countries, and many people in ASEAN countries are affected, along with frequent occurrences of flooding due to typhoons and torrential rains. In particular, the Bandung region which is located in the Upper Chitarum River basin in Indonesia has topographical characteristics in the form of a basin, making it very vulnerable to flooding. Accordingly, through the Official Development Assistance (ODA), a flood forecasting and warning system was established for the Upper Citarium River basin in 2017 and is currently in operation. Nevertheless, the Upper Citarium River basin is still exposed to the risk of human and property damage in the event of a flood, so efforts to reduce damage through fast and accurate flood forecasting are continuously needed. Therefore, in this study an artificial intelligence-based river flood water level forecasting model for Dayeu Kolot as a target station was developed by using 10-minute hydrological data from 4 rainfall stations and 1 water level station. Using 10-minute hydrological observation data from 6 stations from January 2017 to January 2021, learning, verification, and testing were performed for lead time such as 0.5, 1, 2, 3, 4, 5 and 6 hour and LSTM was applied as an artificial intelligence algorithm. As a result of the study, good results were shown in model fit and error for all lead times, and as a result of reviewing the prediction accuracy according to the learning dataset conditions, it is expected to be used to build an efficient artificial intelligence-based model as it secures prediction accuracy similar to that of using all observation stations even when there are few reference stations.

• Journal of the Korean Society of Safety
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• v.35 no.1
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• pp.107-115
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• 2020

This paper introduces the first vital area identification (VAI) process for the physical protection of nuclear power plants (NPPs) during low power and shutdown (LPSD) operation. This LPSD VAI is based on the 3rd generation VAI method which very efficiently utilizes probabilistic safety assessment (PSA) event trees (ETs). This LPSD VAI process was implemented to the virtual NPP during LPSD operation in this study. Korea Atomic Energy Research Institute (KAERI) had developed the 2nd generation full power VAI method that utilizes whole internal and external (fire and flooding) PSA results of NPPs during full power operation. In order to minimize the huge burden of the 2nd generation full power VAI method, the 3rd generation full power VAI method was developed, which utilizes ETs and minimal PSA fault trees instead of using the whole PSA fault tree. In the 3rd generation full power VAI method, (1) PSA ETs are analyzed, (2) minimal mitigation systems for avoiding core damage are selected from ETs by calculating system-level target sets and prevention sets, (3) relatively small sabotage fault tree that has the systems in the shortest system-level prevention set is composed, (4) room-level target sets and prevention sets are calculated from this small sabotage fault tree, and (5) the rooms in the shortest prevention set are defined as vital areas that should be protected. Currently, the 3rd generation full power VAI method is being employed for the VAI of Korean NPPs. This study is the first development and application of the 3rd generation VAI method to the LPSD VAI of NPP. For the LPSD VAI, (1) many LPSD ETs are classified into a few representative LPSD ETs based on the functional similarity of accident scenarios, (2) a few representative LPSD ETs are simplified with some VAI rules, and then (3) the 3rd generation VAI is performed as mentioned in the previous paragraph. It is well known that the shortest room-level prevention sets that are calculated by the 2nd and 3rd generation VAI methods are identical.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.3
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• pp.141-152
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• 2017

This paper presents a technical method for flood estimation based on satellite rainfall and satellite rainfall correction method for watersheds lacking measurement data. The study area was the Sebou Watershed, Morocco. The Integrated Flood Analysis System(IFAS) and Grid-based Rainfall-Runoff Model(GRM) were applied to estimate watershed runoff. Daily rainfall from ground gauges and satellite-derived hourly data were used. In the runoff simulation using satellite rainfall data, the composites of the daily gauge rainfall and the hourly satellite data were applied. The Shuttle Radar Topographic Mission Digital Elevation Model(SRTM DEM) with a 90m spatial resolution and 1km resolution data from Global map land cover and United States Food and Agriculture Organization(US FAO) Harmonized World Soil Database(HWSD) were used. Underestimated satellite rainfall data were calibrated using ground gauge data. The simulation results using the revised satellite rainfall data were $5,878{\sim}7,434m^3/s$ and $6,140{\sim}7,437m^3/s$ based on the IFAS and GRM, respectively. The peak discharge during flooding of Sebou River Watershed in 2009~2010 was estimated to range from $5,800m^3/s$ to $7,500m^3/s$. The flood estimations from the two hydrologic models using satellite-derived rainfall data were similar. Therefore, the calibration method using satellite rainfall suggested in this study can be applied to estimate the flood discharge of watersheds lacking observational data.

• Journal of the Korean earth science society
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• v.33 no.7
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• pp.596-607
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• 2012

The R-Z relationship is one of important error factors to determine the accuracy of radar rainfall estimation. In this study, we have explored the effect of the R-Z relationships derived from disdrometer data in estimating the radar rainfall. The heavy rain event that produced flooding in St-Remi, Quebec, Canada has been occurred. We have tried to investigate the severity of rain for this event using high temporal (2.5 min) and spatial resolution ($1^{\circ}$ by 250 m) radar data obtained from the McGill S-band radar. Radar data revealed that the heavy rain cells pass directly over St-Remi while the coarse raingauge network was not sufficient to detect this rain event. The maximum 30 min (1 h) accumulation reaches about 39 (42) mm in St-Remi. During the rain event, the two disdrometers (POSS; Precipitation Occurrence Sensor System) were available: One used for the reflectivity calibration by comparing disdrometer Z and radar Z and the other for deriving disdrometric R-Z relationships. The result shows the significant improvement with the disdrometric reflectivity-dependent R-Z relationships against the climatological R-Z relationship. The bias in radar rain estimation is reduced from +12% to -2% and the root-mean squared error from 16 to 10% for daily accumulation. Using the estimated radar rainfall rate with disdrometric R-Z relationships, the flood event was well captured with proper timing and amount.

• Journal of Korea Water Resources Association
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• v.50 no.2
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• pp.111-119
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• 2017

The underflow type movable weirs were arranged in a multi-stage way along a reach at the Chiseong River, where flooding has been observed frequently. With management water level of the movable weirs the control effects of storage and flood were suggested and the control effects were compared with those of existed weir system. The water level for the targeted storage and flood elevation was suggested by building the artificial neural network model. When the underflow type of movable weirs were arranged in a multi-stage way, the peak flood elevation decreased by 68.28% in the downstream compared with the existed weir system, and the total storage of the target section of multi-stage movable weirs increased by 216%. As a result of numerical simulation to build the artificial neural network model, 60%, 20%, and 20% among 216 data were used for the training, validation, and test, respectively. The training result of mean square error was $0.1681m^2$ and the high coefficients of determination were 0.9961, 0.9967, and 0.9943 in the training, validation, and test, respectively. As a result the water level management of each movable weir for the controls of flood elevation in the targeted downstream and targeted storage was suggested by using the artificial neural network.

• Korean Journal of Weed Science
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• v.15 no.3
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• pp.175-182
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• 1995

The experiment was conducted to obtain basic information on weed ecology and effective weed control in direct-seeded rice Gelds at National Yeongnam Agricultural Experiment Station in 1994. Double cropping system of rice-barley reduced weed occurrence about 30% as compared with rice single cropping due to allelopathic effect of barley residue or stubble. Occurrences of red rice (weedy rice), barnyard grass and water foxtail were closely related with tillage method; the greatest occurred in no tillage plot followed by rotavation only and plow plus rotavation. Period of seed germination of barnyard grass and carbgrass varied with temperature and soil depth. In the same environmental condition, the germination period of barnyard grass shortened 3 to 5 days as compared with that of carbgrass. Two systematic applications of herbicides, that is, the first application at 10 to 15 days after seeding and the second at just after flooding, were the most recommendable system in dry-seeded rice field in terms of weed suppression and yield capacity.

• Journal of Korea Water Resources Association
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• v.39 no.5 s.166
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• pp.405-415
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• 2006

The deposition of sewer solids during dry weather in combined sewer systems results in a loss of flow capacity that may restrict flow and cause a local flooding and enhanced solids deposition. Sewer solid accumulations in drainage systems also create the 'first-flush' phenomena during wet weather runoff periods. In order to solve these problems, measurement of these loadings for a given sewer system for extended period is needed but this task is very difficult and extremely expensive. In this study, generalized procedures for estimating sewer sediment solid during dry weather in combined sewer systems developed by the U. S. Environmental Protection Agency were applied in a drainage system in Korea. As result, the appropriate equation can be selected and applied according to the available data. However, the estimated solid sediment shows considerable difference between methods which classified by model and estimation methods of variable. The estimated values using equations (1) $\sim$ (4) are greater than that of equations (5) $\sim$ (9) and intermediate models show greater values than elaborate or simplest models. The comparison between simulated and measured solid deposition is difficult due to the absent of measurement data, but this estimation method can be used usefully for the management of sewer solid with reduction of cost and effort if the measurement is carried out and the equation is adjusted according to the actual drainage systems in Korea.

• Korean Journal of Weed Science
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• v.18 no.2
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• pp.116-121
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• 1998

Field experiment were carried out to elucidate the changes of weed occurrence according to the sowing time and to establish the efficient weed control system in dry seeded rice cultivation. E crus-galli and D. sanguinalis are tow major weeds at the earlier sowings, but C. difformis was dominating at the later sowing. In the case of E. crus-galli, there was a tendency of gaining its dominance values as the rice growth stage advances. The later the sowing time was, the more weeds occurred at the early rice growth stages: However, when measured at heading, total dry weight was greater at the earlier sowings. Yield loss due to weeds were also greater at the earlier sowings. Community diversity of weeds was greater at the later sowings, while specific weed was gradually dominating as rice growth stage advances, regardless of sowing time. When herbicides were applied before 15 DAS, weeds were effectively controlled only upto 35 DAS. So systemic herbicide application, one on 0 to 10 DAS and the other on just after flooding, appeared to be recommendable in direct seeded rice cultivation.

• 한국해양학회지
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• v.26 no.3
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• pp.181-192
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• 1991

Zooplankton were sampled horizontally with a standard net from the surface layer of the estuarine system of Mankyong River and Dongjin River in October, 1989, March, May, and July, 1990. Among dominant taxa of the zooplankton community, copepods were predominant in October, 1989 and March, 1990 and Noctiluca scintillans in May and July, 1990. Abundance of zooplankton showed considerable spatial and temporal fluctuations with a range of $12~9,256ind./m^3$ in wet weight. In the copepod community, Pseudodiaptomus inopinus and Paracalanus inducus were predominant in October, 1989: Acartia hudosonica and P. inducus in March, 1990; A. hudosonica and Centropages abdoinalis in May, 1990; A. pacifica, P. indicus and Tortanus spinicaudatus in July. 1990. In summer (July),there were large seasonal changes in salinity ($0.7~28.9\textperthousand$), due to monsoonal flooding, and associated changes in community structured of copepods. There were eight species of copepods in the mixo-mesohaline zone ($5.0~28.8\textperthousand$), namely Acartia pacifica, A. hudosonica, Centropages tenuiremis, C. abdominalis, Labidocera Euchaeta, Tortanus spinicaudatus, corycaeus affinis and Paracalanus indicus. On the other hand, Thermocouple hyalinus, Pseudodiaptomus inopinus and Sinocalanus tenellus occurred in the mixo-oligohaline zone ($0.5~5.0\textperthousand$), showing more tolerant of low salinity than any of the other species. In the mixoeuhaline zone ($>28.0\textperthousand$), Labidocera bipinnata, Oithona similes, Calanus sinicus, Acartia omorii and Tortanus forcipatus were founded.

• The Journal of the Korea Contents Association
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• v.18 no.12
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• pp.646-659
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• 2018

This study proposed "Reservoir Park", which added disaster prevention function to urban green spaces such as city parks through domestic and overseas related laws review, case studies, field trips. This is a combination of urban parks and reservoirs as urban planning facilities, which can provide both space for daily use by urban residents and disaster mitigation functions in case of emergency. In order to prevent flooding in urban areas due to climate change, facilities should be installed in the form of parks, etc., as the reservoir facility should be systematically reviewed together with urban planning facilities. However it was found that the reservoir park was not clear as a theme park. In this study, the types of storage facilities in urban areas were reclassified into five types of storage parks reflecting the characteristics of urban green spaces through domestic case studies and field trips. The classification of the reservoir parks is classified into 5 kinds such as ecological type, vegetation cover type, exercise facility type, underground burial type and hybrid type based on groundwater level, human use, and reservoir size. This classification system can be used to determine the types of facilities to be built after designating the location of future storage facilities.