• Journal of Korea Water Resources Association
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• v.56 no.11
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• pp.775-784
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• 2023

With the increasing trend of extreme rainfall that exceeds the design frequency of man-made structures due to extreme weather, it is necessary to review the safety of agricultural reservoirs designed in the past. However, there are no local government-managed reservoirs (13,685) that can be discharged in an emergency, except for reservoirs over a certain size under the jurisdiction of the Korea Rural Affairs Corporation. In this case, it is important to quickly deploy a mobile siphon to the site for preliminary discharge, and this study evaluated the applicability of a mobile siphon with a diameter of 200 mm, a minimum water level difference of 6 m, 420 (m²/h), and 10,000 (m²/day), which can perform both preliminary and emergency discharge functions, to the Yugum Reservoir in Gyeongju City. The test bed, Yugum Reservoir, is a facility that was completed in 1945 and has been in use for about 78 years. According to the hydrological stability analysis, the lowest height of the current dam crest section is 27.15 (EL.m), which is 0.29m lower than the reviewed flood level of 27.44 (EL.m), indicating that there is a possibility of lunar flow through the embankment, and the headroom is insufficient by 1.72 m, so it was reviewed as not securing hydrological safety. The water level-volume curve was arbitrarily derived because it was difficult to clearly establish the water level-flow relationship curve of the reservoir since the water level-flow measurement was not carried out regularly, and based on the derived curve, the algorithm for operating small and medium-sized old reservoirs was developed to consider the pre-discharge time, the amount of spillway discharge, and to predict the reservoir lunar flow time according to the flood volume by frequency, thereby securing evacuation time in advance and reducing the risk of collapse. Based on one row of 200 mm diameter mobile siphons, the optimal pre-discharge time to secure evacuation time (about 1 hour) while maintaining 80% of the upper limit water level (about 30,000 m²) during a 30-year flood was analyzed to be 12 hours earlier. If the pre-discharge technology utilizing siphons for small and medium-sized old reservoirs and the algorithm for reservoir operation are implemented in advance in case of abnormal weather and the decision-making of managers is supported, it is possible to secure the safety of residents in the risk area of reservoir collapse, resolve the anxiety of residents through the establishment of a support system for evacuating residents, and reduce risk factors by providing risk avoidance measures in the event of a reservoir risk situation.

• The Korean Journal of Health Service Management
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• v.10 no.3
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• pp.63-74
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• 2016

Objectives : There is a need to develop a data quality management algorithm to improve the quality of healthcare data using a data quality management system. In this study, we developed a data quality control algorithms associated with diseases related to hypertension in patients with diabetes mellitus. Methods : To make a data quality algorithm, we extracted the 2011 and 2012 discharge damage survey data from diabetes mellitus patients. Derived variables were created using the primary diagnosis, diagnostic unit, primary surgery and treatment, minor surgery and treatment items. Results : Significant factors in diabetes mellitus patients with hypertension were sex, age, ischemic heart disease, and diagnostic ultrasound of the heart. Depending on the decision tree results, we found four groups with extreme values for diabetes accompanying hypertension patients. Conclusions : There is a need to check the actual data contained in the Outlier (extreme value) groups to improve the quality of the data.

• Journal of Korean Society on Water Environment
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• v.29 no.2
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• pp.259-269
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• 2013

This study aims to show the feasibility of wastewater reuse through hydrological analysis and propose a framework for planning using multi-criteria decision making technique. Ten alternatives of wastewater reuse (BOD: 3.0 mg/L & 4.7 mg/L) and two references in the urban watershed were considered and analyzed by using Hydrological Simulation Program in Fortran (HSPF). Though wastewater reuse has a positive effect on water quantity, it may degrade the water quality due to the high discharge concentration. This study showed that wastewater reuse can be a great alternative for the rehabilitation of distorted water cycle, if the quality is improved up to the natural streamflow and the quantity is increased up to the instreamflow requirement. In addition, to determine the project priority, three criteria were compared: 1) impacts on water quantity and water quality, respectively, 2) consideration of present hydrologic vulnerabilities on water quantity and quality and not, and 3) social and economic considerations and not. From the performance values to all criteria, the specific ranking can be derived and the feasibility of each wastewater reuse project can be checked with the comparison of the existing facilities. As a result, DJ and DR were derived to become effective in any evaluation conditions while SS and WG were improper alternatives if various criteria were considered. The decision making for project prioritization must be careful with the consideration of various impacts of wastewater reuse because the evaluation of wastewater reuse alternative showed very different priorities for each criteria.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2668-2676
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• 2011

In order to analyze the variation in length of stay(LOS) of injury inpatients, we developed severity-adjusted LOS model using Korean National Discharge In-depth Injury Survey data of Center for Disease Control. Appling this model, we calculated predicted values and, after standardizing LOS using the differences from the actual values, analyzed the variation in LOS. Major factors affecting severity-adjusted LOS of injury inpatients were found to be severity, surgery(or no surgery), age, injury mechanism and channel of hospitalization. Result of analysis of the differences between the actual values and predicted values adjusted by decision tree model suggested that there were statistically significant differences by hospital size(number of beds), type of insurance and location of institution. In order to reduce the variation in LOS, efforts should be exerted in developing nationwide treatment protocol, inducing medical institutions to utilize it, and furthermore systematically evaluating it to reduce the variation continually.

• Journal of the Korean Institute of Gas
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• v.24 no.6
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• pp.91-97
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• 2020

Lithium-ion batteries (LIBs) have a longer lifespan, higher energy density, and lower self-discharge rates than other batteries, therefore, they are preferred as an Energy Storage System (ESS). However, during years 2017-2019, 28 ESS fire accidents occurred in Korea, and accurate capacity estimation of LIB is essential to ensure safety and reliability during operations. In this study, data-driven modeling that predicts capacity changes according to the charging cycle of LIB was conducted, and developed models were compared their performance for the selection of the optimal machine learning model, which includes the Decision Tree, Ensemble Learning Method, Support Vector Regression, and Gaussian Process Regression (GPR). For model training, lithium battery test data provided by NASA was used, and GPR showed the best prediction performance. Based on this study, we will develop an enhanced LIB capacity prediction and remaining useful life estimation model through additional data training, and improve the performance of anomaly detection and monitoring during operations, enabling safe and stable ESS operations.

• Journal of Korean Society for Quality Management
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• v.51 no.4
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• pp.551-571
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• 2023

Purpose: The purpose of this study is to propose useful suggestions by analyzing the causal effect relationship between the failure rate of quality and the process variables in the C5ISR domain of the defense industry. Methods: The collected data through the in house Systems were analyzed using Big data analysis. Data analysis between quality data and A/S history data was conducted using the CRISP-DM(Cross-Industry Standard Process for Data Mining) analysis process. Results: The results of this study are as follows: After evaluating the performance of candidate models for the influence of inspection data and A/S history data, logistic regression was selected as the final model because it performed relatively well compared to the decision tree with an accuracy of 82%/67% and an AUC of 0.66/0.57. Based on this model, we estimated the coefficients using 'R', a data analysis tool, and found that a specific variable(continuous maximum discharge current time) had a statistically significant effect on the A/S quality failure rate and it was analysed that 82% of the failure rate could be predicted. Conclusion: As the first case of applying big data analysis to quality issues in the defense industry, this study confirms that it is possible to improve the market failure rates of defense products by focusing on the measured values of the main causes of failures derived through the big data analysis process, and identifies improvements, such as the number of data samples and data collection limitations, to be addressed in subsequent studies for a more reliable analysis model.

• Journal of Wetlands Research
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• v.17 no.3
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• pp.237-244
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• 2015

This study is estimated the flood damage probability of the flood discharge, the flood stage estimation and Economic Analysis for Flood Control about considering of uncertainty. Sum River Basin has chosen and the probability precipitation is estimated by using the concept of critical rainfall duration depending on the frequency of each flood stage estimation point. For calculating the expected annual damage, the functions of long term hazard, discharge-frequency, stage-discharge and depth-damage are established for 8 areas in Sum River Basin. The expected annual damaged is obtained which is based on the sampling informations through more than 500,000 simulation from the functions of considered uncertainty. The result about the optimum frequency and Investment Priorities are estimated by conducting the evaluation about planning the levee of various of Design Frequency. In analysis result, 12% of B/C value has increased if the uncertainty has concerned. Also the optimum frequency or Investment Priorities are possible to be changed. If the political and social analysis perform together it would be helpful to have a reasonable decision other than only the economical analysis as actual Flood damaged reduction planning.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.549-557
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• 2013

An flood inundation map is able to convey spatial distribution of inundation to a decision maker for flood risk management. A roughness coefficient with unclear values and a discharge obtained from the stage-discharge rating equation are key sources of uncertainty in flood inundation mapping by using a hydraulic model. Also, the uncertainty analysis needs an observation for the flood inundation, and satellite images is useful to obtain spatial distribution of flood. Accordingly, the objective of this study is to quantify uncertainty arising roughness and discharge in flood inundation mapping by using a hydraulic model and a satellite image. To perform this, flood inundations were simulated by HEC-RAS and terrain analysis, and ISODATA (Iterative Self-Organizing Data Analysis) was used to classify waterbody from Landsat 5TM imagery. The classified waterbody was used as an observation to calculate F-statistic (likelihood measure) in GLUE (Generalized Likelihood Uncertainty Estimation). The results from GLUE show that flood inundation areas are 74.59 $km^2$ for lower 5 % uncertainty bound and 151.95 $km^2$ for upper 95% uncertainty bound, respectively. The quantification of uncertainty in flood inundation mapping will play a significant role in realizing the efficient flood risk management.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.4
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• pp.37-44
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• 2013

Concentrated localized torrential rains due to global warming and climate change have resulted in much water damage each year. GIS is used as a tool for predicting the peak-outflows caused by these regional torrential rains in mountainous rivers. However, the research of the resolution of the data is limited, and most of approaches are about hydrological geographic. This paper estimates the flood discharge needed for decision of standard rainfall of automatic rainfall warning system by using GIS with GcIUH model, and establishes the criteria of flash flood warning. It also has analyzed the terrain in river basin, extracted the morphological characteristics parameters of water shed such as stream width, channel slope, channel length, shape factor, and GcIUH parameters, and analyzed the relationship between them.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.6
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• pp.718-724
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• 2014

Insensitive Munition(IM) reduces the explosive weakness of munitions, at the same time, maintains its performances in the moment of discharge, which improves safety of soldiers and minimizes unexpected accidents and casualties from being shot in case of transportation, storage and military operation. Development of IM has been focused as the global trend, which was required to satisfy the demand of army that is to minimize the loss of non-battle forces and to retain the competitiveness in export abroad. In this study, we categorize all the munitions used by ROK Army, then determine the priority of IM by deploying AHP(Analytic Hierarchy Process) method. In conclusion, we suggest the priority of IM which is suitable to the affairs of ROK Army.