• Journal of Korea Water Resources Association
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• v.46 no.2
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• pp.195-204
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• 2013

As drought is phenomenon of nature with unavoidability and repeated characteristic, it is necessary to plan to respond to it in advance and construct drought management system to minimize its damage. This study suggested standard for classification of drought, which is appropriate for our nation to respond to drought by assessing drought severity in the regions for this study. For data collection, 61 locations were selected - the locations keep precipitation data over 30 years of observation. And data for monthly precipitation for 37 years from 1973 were used. Based on this, this study classified unified drought interval into four levels using drought situation phases which are used in government. For standard for classification of drought severity fit to our nation, status of main drought was referred and these are classified based on accumulated probability of drought - 98~100% Exceptional Drought, 94~98% Extreme Drought, 90~94% Severe Drought, 86~90% Moderate Drought. Drought index (SPI, PDSI) was made in descending order and quantitative value of drought index fit to standard of classification for drought severity was calculated. To compare classification results of drought severity of SPI and PDSI with actual drought, comparison by year and month unit were analyzed. As a result, in comparison by year and comparison by month unit of SPI, drought index of each location was mostly identical each other between actual records and analyzed value. But in comparison by month unit of PDSI for same period, actual records did not correspond to analyzed values. This means that further study about mutual supplement for these indexes is necessary.

• Journal of the Korea Institute of Building Construction
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• v.20 no.1
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• pp.83-91
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• 2020

The recent bridge construction projects is demanded more sophisticated risk management measures and loss forecasts to brace for risk losses from an increase in the trend of bridge construction. This study aims to analyze the risk factors that caused the loss of material in actual bridge construction and to develop a quantified predictive loss model, based on the past record of insurance payment by major domestic insurance companies for bridge construction projects. For the development of quantitative bridge construction loss model, the dependent variable was selected as the loss ratio, i.e., the ratio of insurance payout divided by the total project cost, while the independent variable adopted 1) Technical factors: superstructure type, foundation type, construction method, and bridge length 2) Natural hazards: typhoon and flood 3) Project information: construction period and total project cost. Among the selected independent variables, superstructure type, construction method, and project period were shown to affect the ratio of bridge construction losses. The results of this study can provide government agencies, bridge construction design and construction and insurance companies with the quantitative damage prediction and risk assessment services, using risk indicators and loss prediction functions derived from the findings of this study and can be used as a guideline for future basic bridge risk assessment development research.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.545-553
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• 2021

The frequency by water disaster in urban areas are increasing continuously due to climate change and urbanization. Countermeasures are being conducted to reduce the damage caused by water disasters. An analysis based on permeability, one of the parameters that affect runoff, is needed to predict quantitative runoff in urban watersheds and study runoff reduction. In this study, the SWAT model was simulated for the oncheon stream basin, a representative urban stream in Busan. The permeability map was prepared by calculating the CN values for each hydrologic response unit. Based on the permeability map prepared, EPA SWMM analyzed the effect of LID technology application on the water cycle in the basin for short-term rainfall events. The LID element technology applied to the oncheon stream basin was rooftop greening in the residential complex, and waterproof packaging was installed on the road. The land cover status of the land selected based on the permeability map and the application of LID technology reduced the outflow rate, peak flow rate, and outflow rate and increased the infiltration. Hence, LID technology has a positive effect on the water cycle in an urban basin.

• Journal of Wetlands Research
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• v.23 no.2
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• pp.154-162
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• 2021

The naturally opened Han river estuary is a place where the flows of the Han river, Imjin river, Yaesung river meet with West Sea of Korea, so the hydrodynamic mechanism(Impact-Response) structure of Han river estuary is complex. Continuous observation and measurement due to the morphological characteristics at the estuary are required to maintain the estuary environment and river management facilities. However, the Sannam wetland(the study area) is in the military operation area. Therefore, Sannam wetland has the limited access under the control from military office. In 2020, there had a natural disaster due to flooding in August and COVID-19, and it made a survey hard. The noncontact survey technique, the analysis of LANDSAT images at Sannam wetland, was applied to analyze riverbed fluctuation and morphological transformation around Sannam wetland. LANDSAT images obtained from EarthExplorer, USGS and analyzed by QGIS. The analysis was performed based on the area and the distance near Sannam wetland. As a result, an erosion was happened on the downstream of the study area, and the upstream of the study area did not have any serious sediment transport. Considering the resolution of LANDSAT images, this noncontect survey technique is applicable to manage the study area. From the analysis of LANDSAT images, it is assumed that the tidal effect is greater than the inflow from the upstream. The pattern change of tidal response causes the damage of the river facilities near the Hangang river estuary.

• Journal of the Korean Association of Geographic Information Studies
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• v.27 no.2
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• pp.34-44
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• 2024

Recently, due to abnormal climate caused by climate change, natural disasters such as floods, landslides, and soil outflows are rapidly increasing. In Korea, more than 63% of the land is vulnerable to slope disasters due to the geographical characteristics of mountainous areas, and in particular, Quarry mines soil and rocks, so there is a high risk of landslides not only inside the workplace but also outside.Accordingly, this study built a DEM using UAV and aviation LiDAR for monitoring the quarry, conducted a time series change analysis, and proposed an optimal DEM construction method for monitoring the soil collection site. For DEM construction, UAV and LiDAR-based Point Cloud were built, and the ground was extracted using three algorithms: Aggressive Classification (AC), Conservative Classification (CC), and Standard Classification (SC). UAV and LiDAR-based DEM constructed according to the algorithm evaluated accuracy through comparison with digital map-based DEM.

• Journal of Korea Water Resources Association
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• v.54 no.spc1
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• pp.1095-1105
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• 2021

The advancement of dam operation is further required due to the upcoming rainy season, typhoons, or torrential rains. Besides, physical models based on specific rules may sometimes have limitations in controlling the release discharge of dam due to inherent uncertainty and complex factors. This study aims to forecast the water level of the nearest station to the dam multi-timestep-ahead and evaluate the availability when it makes a decision for a release discharge of dam based on LSTM (Long Short-Term Memory) of deep learning. The LSTM model was trained and tested on eight data sets with a 1-hour temporal resolution, including primary data used in the dam operation and downstream water level station data about 13 years (2009~2021). The trained model forecasted the water level time series divided by the six lead times: 1, 3, 6, 9, 12, 18-hours, and compared and analyzed with the observed data. As a result, the prediction results of the 1-hour ahead exhibited the best performance for all cases with an average accuracy of MAE of 0.01m, RMSE of 0.015 m, and NSE of 0.99, respectively. In addition, as the lead time increases, the predictive performance of the model tends to decrease slightly. The model may similarly estimate and reliably predicts the temporal pattern of the observed water level. Thus, it is judged that the LSTM model could produce predictive data by extracting the characteristics of complex hydrological non-linear data and can be used to determine the amount of release discharge from the dam when simulating the operation of the dam.

• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.473-477
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• 2010

Cucumber green mottle mosaic virus (CGMMV) is one of major plant viruses infecting cucurbitaceous crops via soil or infected seeds. This study investigate ecology of infection of CGMMV in soil, and control tactics of this virus with soil hygiene and crop rotation. This virus was survival to 50% in soil without host plants for 17 months and had high vitality in debris of infected plant over 1 year. Infection rate of CGMMV was 1.0~3.6% in control soil and 12~36% in soil transplanted with wounded root of watermelon. It showed that wounded root may affect severity of soil infection. Rotation between rice and watermelon caused dramatical reduction from 76.8% in repeated cultivation to 7.3% of progeny infection by CGMMV. Therefore, it is suggested that crop rotation be effective for control of CGMMV.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.705-711
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• 2008

In case of the domestic condition, as the initiating from Sumjin River Dam, total 14 units of multipurpose dams had been constructed in 1965 for the roles of flood control, waterpower generation, irrigation, water supply, industrial water supply. In the case of such multipurpose dam, it produces electric energy by converting the potential energy utilizing its head and quantity of the water into kinetic energy. However, in this process, since during the time when the turbine connected to the hydraulic turbine dynamo revolves and there occurs a loud noise, it brings the physical, mental bad influences to those people also a decline of an effective working efficiency. On such point of view, after selection of various 16 measurement points, this study has measured and analyzed the travelling characteristics of noise generated at the hydraulic turbine dynamo in Daechung Dam, and also has evaluated the degree of indoor noise using the evaluation index such as PSIL, NC. As the result of noise-evaluation, in case of Daechung Dam, since the noise damage grade appears very seriously at various spaces, it is considering that its soundproof measure would be necessitated keenly. Also, it is considered that such data could be utilized as the valuable material hereafter for establishment of an efficient noise-reduction countermeasure and a comfortable working environment for the hydraulic turbine dynamo plant.

• Journal of the Korea Society of Computer and Information
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• v.24 no.12
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• pp.157-166
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• 2019

Globally, various disasters such as typhoons, floods, earthquakes, fires, explosions have caused work to be halted. If there is a large-scale disaster at public institutions in charge of major national affairs and their works are interrupted, not only will there be property damage, but there will also lead to a decline in national credibility and direct and indirect impacts on the people. Therefore, it is necessary to ensure continuity of operation by minimizing the interruption period of critical operations due to disasters. Overseas advanced countries such as the United States and Japan developed guidelines for Continuity of Operation (COOP) to prevent unexpected work disruptions caused by disasters. Recognizing the necessity of COOP in South Korea, a relevant law has been newly established in 「the Framework Act on the Management of Disasters and Safety」 to enable public institutions to establish the COOP in response to this situation. In this study, the definition, the necessity and overseas cases of COOP were investigated and described. Using the templates developed by these results, operational impact analysis, risk assessment, operational continuity strategies and operational continuity procedures were applied to "A" City Hall in Gyeonggi-do province and those results were described. The objective of this study is to substantially contribute to the introduction of COOP to local governments through their pilot application and implications of COOP.