• Journal of Korea Water Resources Association
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• v.46 no.1
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• pp.35-45
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• 2013

The aim of study is to present how to estimate and use the FRI (Flood Risk Index) for classifying area zones based on regional flooding risk in terms of the integrated flood risk management. To estimate the FRI at a spatial resolution of city/county/town units for the Nakdong River Watershed, the 17 representative flood indexing factors are carefully selected for the three flood indexes, such as PI (Pressure Index), SI (State Index), and RI (Response Index) under the P-S-R (Pressure-State-Response) classification system. Because flood indexing factors are measured at different scales and units, they are transformed into a common domain by the T-Score normalization technique. The entropy weight coefficient method is also applied to calculate the weight of flood indexing factors in order to reduce subjective judgement on the effect of weight coefficients. The three flood indexes of PI, SI, and RI are integrated for an overall value of the FRI to evaluate the flood risk of districts. To examine the practical application of the proposed FRI, the FRI results with/without the weight coefficients are compared with flooding zones of natural disaster risk areas officially announced in 2010. It is expected that the FRI ensured by full verification can make regional protection plans against flooding disasters with respect to causes and characteristics of past floods.

• Spatial Information Research
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• v.10 no.4
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• pp.493-499
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• 2002

This paper presents the disaster control due to flooding through the case study of Samwhadong, Donghae city, Kangwondo, broken out at 31, August 2002. In order to assess the characteristics of flood damage one must consider social and geological conditions, the factors of flood risk were derived based on GIS. For reduction of flood damage, flood hazard map was prepared for local residents. These information will support refuge activities, it would aid the reduction of flood damage.

• Nuclear Engineering and Technology
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• v.49 no.2
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• pp.360-372
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• 2017

Many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended because of deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Considering an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive Reactor Cavity Cooling System following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. Although this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability of the Reactor Cavity Cooling System (and the reactor system in general) for the postulated transient event.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.682-686
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• 2005

Recently some urban areas have been flooded due to heavy storm rainfalls. Though major causes of these floodings may be attributed to localized heavy rainfalls, other factors are related to urban flooding including deficiency of storm sewer network capacity, change of surface runoff due to covered open channels, and operational problems of storm drainage pump stations. In this study, hydrologic and hydraulic analysis of Sutak basin in Guri city were carried out to evaluate flooding problems occurred during the heavy storm in July, 2001. ArcView, a world most widely used GIS tool, was used to extract required data for the hydrologic analysis including basin characteristics data, concentration times, channel routing data, land use data, soil distribution data and SCS runoff curve number generation from digital maps. HEC-HMS, a GIS-based runoff simulation model, was successfully used to simulate the flood inflow hydrograph to Sutak pumping station.

• Fire Science and Engineering
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• v.17 no.4
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• pp.70-75
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• 2003

The east coast of Kangwon province has been suffering from natural disaster like wildfire and flooding. In April 2000, there has been a great wildfire in this area. Many forest was burnt out, the mountain was bared. Furthermore, on 31st August,2002 typhoon RUSA attacked the area with heavy rainfall of about 315 mm/day, which resulted in 178 deaths and extensive damage to the property, In this regard, our study was focused on the assessment of the factors of flooding damage considering wildfire disaster. Most of results for our study are derived from practical investigation in the east coast of Kangwon province.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.9
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• pp.725-733
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• 2002

In this study, the heat transport limitations of a two-phase closed thermosyphon were investigated. For the test, a two-phase closed thermosyphon ($L_t/: 600 mm,\;L_e:105mm,\;L_a:75mm,\;L_c:420mm,\;D_o:22.2mm,$ container: copper (inner grooved surface), working fluid: PFC ($C_6F_14$) was fabricated with a reservoir that can change the fill charge ratio. The following was imposed as the factors on the heat transport limitations of a two-phase closed thermosyphon. 1) Fill charge ratio of the working fluid. 2) Tilt angle of the longitudinal axis. From tile experimental data, some results were obtained as follows. When the fill charge ratio was relatively small ($\psi$20%), the heat transport limitation occurred about 100W by dry-out limitation. However over 40%, it shelved nearly constant value (500 W) by flooding limitation. The heat transport limitation according to the tilt angle increased smoothly until the tilt angle was $60^{\circ}$,/TEX>, after then decreased slowly.

• Korean Journal of Remote Sensing
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• v.39 no.5_2
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• pp.771-783
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• 2023

This study aims to compare the performance of each machine learning model for preparing a grid-based disaster risk map related to flooding in Jung-gu, Ulsan, for Typhoon Chaba which occurred in 2016. Dynamic data such as rainfall and river height, and static data such as building, population, and land cover data were used to conduct a risk analysis of flooding disasters. The data were constructed as 10 m-sized grid data based on the national point number, and a sample dataset was constructed using the risk value calculated for each grid as a dependent variable and the value of five influencing factors as an independent variable. The total number of sample datasets is 15,910, and the training, verification, and test datasets are randomly extracted at a 6:2:2 ratio to build a machine-learning model. Machine learning used random forest (RF), support vector machine (SVM), and k-nearest neighbor (KNN) techniques, and prediction accuracy by the model was found to be excellent in the order of SVM (91.05%), RF (83.08%), and KNN (76.52%). As a result of deriving the priority of influencing factors through the RF model, it was confirmed that rainfall and river water levels greatly influenced the risk.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.161-177
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• 2017

This paper presents the design considerations and field applications on inflatable structure system to protect rapidly flooding damages in large section tunnel. This inflatable structure system is very valuably used to protect passively and rapidly the possibilities of tunnel damages by flooding threats and unusual leakage to be occurred during and after underground infrastructure. In particular, this system should be necessary in subsea tunnel. The predominant factors in the design of inflatable structure system are the leakage and friction characteristics between the inflater and tunnel liner. The analytical and experimental studies are performed to develop the design considerations and to examine the design parameters of the inflatable structure system. The analytical solutions are developed using membrane theory to suggest the design considerations. The relative friction tests of several fabric materials are also carried out to determine the friction characteristics according to the different friction conditions between inflater and tunnel surface. The test results show that the friction coefficients in wet surface condition are about 20% lower than the values in dry surface condition. In addition, virtual design of tunnel protection system for two virtual subsea tunnel sites which is under reviewing in Korea, is carried out based on this research. It is expected that the results of this research will be very useful to understand the inflater structure design and development the technology of tunnel protection structures in the future.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.203-207
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• 2003

As the upending is one of the critical steps in the installation of offshore structure, datail procedure of upending operation is studied in the paper. For larger offshore structure installation, launching method is often applied. However after launching, the upending process is to be followed. To ensure successful upending operation, datail process is analysed considering various factors affecting on the operation including reserved buoyancy, free flotation position, seabed clearance, ballast and hook load. To investigate the influence of each factor on the procedure, twelve numerical jacket models with various dimensions are simulated and studied. From the study, it is revealed that the increase of buoyance and decrease of self weight generate a large seabed clearance. The law seabed clearance during flooding creates higher hook load and height. The paper also introduces a guideline for the related structure design and construction with the effects of contribution factors in the upending operation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.9
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• pp.688-698
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• 2009

Using the multi-dimensional, multi-phase, nonisothermal Polymer Electrolyte Fuel Cell (PEFC) model presented in Part I, the effects of land/channel flow-field on temperature and liquid saturation distributions inside PEFCs are investigated in Part II. The focus is placed on exploring the coupled water transport and heat transfer phenomena within the nonisothermal and two-phase zone existing in the diffusion media (DM) of PEFCs. Numerical simulations are performed varying the land and channel widths and simulation results reveal that the water profile and temperature rise inside PEFCs are considerably altered by changing the land and channel widths, which indicates that oxygen supply and heat removal from the channel to the land regions and liquid water removal from the land toward the gas channels are key factors in determining the water and temperature distributions inside PEFCs. In addition, the adverse liquid saturation gradient along the thru-plane direction is predicted near the land regions by the numerical model, which is due to the vapor-phase diffusion driven by the temperature gradient in the nonisothermal two-phase DM where water evaporates at the hotter catalyst layer, diffuses as a vapor form and then condenses on the cooler land region. Therefore, the vapor phase diffusion exacerbates DM flooding near the land region, while it alleviates DM flooding near the gas channel.