• Journal of The Korean Society of Emergency Medicine
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• v.29 no.6
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• pp.624-635
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• 2018

Objective: This study examined whether emergency department (ED) crowding influences the timing of the initial assessment and treatment in severe trauma patients, as well as their mortality rates. Methods: This retrospective, observational study was conducted between January 2015 and October 2016, and included adult severe trauma patients who presented to the ED. The emergency department occupancy rate (EDOR) was used to measure ED crowding. The patients were divided into four groups using the EDOR quartile. The timeliness of the initial assessment and treatment in the four groups as well as the mortality rates were compared. Results: This study investigated 307 patients. The timing of the first computed tomography (CT) and laboratory test order, CT and laboratory test result acquisition, first transfusion, and patient transfer from the ED to the operating room were similar in the four groups. Multivariable logistic regression analysis did not show a significant difference in mortality between the groups. Conclusion: ED crowding was not associated with delays in the initial assessment and treatment of severe trauma patients, or in their mortality rates.

• Journal of Science Education
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• v.44 no.3
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• pp.331-344
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• 2020

This study aims to find meaningful implications for the development of Korean elementary school math education courses and textbooks by comparing and analyzing the number and arithmetic areas of Korean and Canadian math textbooks in fifth and sixth grades. To this end, the textbook composition system of Korean and Canadian elementary schools was compared and analyzed, and the number and timing of introduction of math textbooks and math textbooks by grade, and the number in fifth and sixth grade and the learning contents of math textbooks were compared and analyzed. The following conclusions were obtained from this study: First, it is necessary to organize a textbook that can solve the problem in an integrated way by introducing the learned mathematical concepts and computations naturally in the context of problems closely related to real life, regardless of the type of private calculation or mathematics area. Second, it is necessary to organize questions using materials such as real photography and mathematics, science, technology, engineering, art, etc. and to organize textbooks that make people feel the necessity and usefulness of mathematics. Third, sufficient learning of the principles of mathematics through the use of various actual teaching aids and mathematical models, and the construction of textbooks focusing on problem-solving strategies using engineering tools are needed. Fourth, in-depth discussions are needed on the timing of learning guidance for fractions and minority learning or how to organize and develop learning content.

• Journal of Korea Water Resources Association
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• v.41 no.2
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• pp.163-172
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• 2008

Hydrologic regimes play a major role in determining the biotic composition, structure, and function of river ecosystem. In this study, hydrologic regimes were analyzed on down stream effects of the Young-Chun dam construction using the Indicators of Hydrologic Alterations(IHA). The analysis results were as follows ; (1) Monthly mean flows were decreased during drought and flood season on the pre and post dam, (2) Magnitude and Duration of Annual Exterm Conditions, annual minima 1-day means was $3.48m^3/sec$, $0.89m^3/sec$ and annual maxima 1-day mean was $833.1m^3/sec$, $672.1m^3/sec$ on the pre and post dam (3) Timing of Annual Exterm conditions, Julian date of the annual minima 1-day means was 180th(June) in the pre dam, 257th(September) in the post dam, Julian date of the annual maxima 1-day means was 209th(July) in the pre dam, 217th(August) in the post dam, (4) Frequency and Duration of High and Low Pulse, Low Puls counts and duration were 3 times and 23 days in the pre dam, High Pulse counts and duration were 4 times and 2 days in the pre dam. (5) Rate and Frequency of Water Condition Changes, rise rates was 39.27 %, 19.36 % and fall rates -15.85 %, -8.16 % in the pre and post dam, respectively (6) Coefficient of Variation, annual exteram water conditions were decreased from 0.9054 to 0.6314 and from 1.0440 to 0.9617, Timing of Annual Exterm conditions were incereased for minima flow from 0.269 to 0.282, for maxima form 0.069 to 0.153.

• Journal of Korea Water Resources Association
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• v.57 no.5
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• pp.333-346
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• 2024

High-resolution medium-range streamflow prediction is crucial for sustainable water quality and aquatic ecosystem management. For reliable medium-range streamflow predictions, it is necessary to understand the characteristics of forcings and to effectively utilize weather forecast data with low spatio-temporal resolutions. In this study, we presented a comparative analysis of medium-range streamflow predictions using the distributed hydrological model, WRF-Hydro, and the numerical weather forecast Global Data Assimilation and Prediction System (GDAPS) in the Geumho River basin, Korea. Multiple forcings, ground observations (AWS&ASOS), numerical weather forecast (GDAPS), and Global Land Data Assimilation System (GLDAS), were ingested to investigate the performance of streamflow predictions with highresolution WRF-Hydro configuration. In terms of the mean areal accumulated rainfall, GDAPS was overestimated by 36% to 234%, and GLDAS reanalysis data were overestimated by 80% to 153% compared to AWS&ASOS. The performance of streamflow predictions using AWS&ASOS resulted in KGE and NSE values of 0.6 or higher at the Kangchang station. Meanwhile, GDAPS-based streamflow predictions showed high variability, with KGE values ranging from 0.871 to -0.131 depending on the rainfall events. Although the peak flow error of GDAPS was larger or similar to that of GLDAS, the peak flow timing error of GDAPS was smaller than that of GLDAS. The average timing errors of AWS&ASOS, GDAPS, and GLDAS were 3.7 hours, 8.4 hours, and 70.1 hours, respectively. Medium-range streamflow predictions using GDAPS and high-resolution WRF-Hydro may provide useful information for water resources management especially in terms of occurrence and timing of peak flow albeit high uncertainty in flood magnitude.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.432-438
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• 2011

The purpose of the present thesis is to develop bankruptcy prediction models capable of being applied to the Korean construction industry and to deduce an optimal model through comparative evaluation of final developed models. A study population was selected as general contractors in the Korean construction industry. In order to ease the sample securing and reliability of data, it was limited to general contractors receiving external audit from the government. The study samples are divided into a bankrupt company group and a non-bankrupt company group. The bankruptcy, insolvency, declaration of insolvency, workout and corporate reorganization were used as selection criteria of a bankrupt company. A company that is not included in the selection criteria of the bankrupt company group was selected as a non-bankrupt company. Accordingly, the study sample is composed of a total of 112 samples and is composed of 48 bankrupt companies and 64 non-bankrupt companies. A financial ratio was used as early predictors for development of an estimation model. A total of 90 financial ratios were used and were divided into growth, profitability, productivity and added value. The MDA (Multivariate Discriminant Analysis) model and BLRA (Binary Logistic Regression Analysis) model were used for development of bankruptcy prediction models. The MDA model is an analysis method often used in the past bankruptcy prediction literature, and the BLRA is an analysis method capable of avoiding equal variance assumption. The stepwise (MDA) and forward stepwise method (BLRA) were used for selection of predictor variables in case of model construction. Twenty two variables were finally used in MDA and BLRA models according to timing of bankruptcy. The ROC-Curve Analysis and Classification Analysis were used for analysis of prediction performance of estimation models. The correct classification rate of an individual bankruptcy prediction model is as follows: 1) one year ago before the event of bankruptcy (MDA: 83.04%, BLRA: 93.75%); 2) two years ago before the event of bankruptcy (MDA: 77.68%, BLRA: 78.57%); 3) 3 years ago before the event of bankruptcy (MDA: 84.82%, BLRA: 91.96%). The AUC (Area Under Curve) of an individual bankruptcy prediction model is as follows. : 1) one year ago before the event of bankruptcy (MDA: 0.933, BLRA: 0.978); 2) two years ago before the event of bankruptcy (MDA: 0.852, BLRA: 0.875); 3) 3 years ago before the event of bankruptcy (MDA: 0.938, BLRA: 0.975). As a result of the present research, accuracy of the BLRA model is higher than the MDA model and its prediction performance is improved.

• Journal of the Korea Society of Computer and Information
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• v.19 no.9
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• pp.75-84
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• 2014

In this paper, we constructed a sensor network environment where various sensors are used. Then, we evaluated the performance when this environment adopted existing clustering algorithms that are designed for only single type sensors network. In our experiments, we considered two different types of the networks. In the first, all nodes are equipped with identical sensors. In the second, all nodes are equipped with three different types of sensors. We measured performance variations of several clustering schemes in accordance with sensor data accuracy, sensor node resource depletion timing, amount of available energy, node isolation ratio, and network lifetime. According to our performance analysis, we proved that existing clustering algorithms are partially inefficient to maintain the various-sensor network. Consequently we suggest that a new algorithm is required to take aim at the various sensor network.

• Journal of Korean Society of Transportation
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• v.29 no.4
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• pp.7-15
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• 2011

Emerged in early 1990s, so called 'Quick service' industry that provides faster delivery of small parcels than regular mail service accelerated use of motorcycles. As the economic grows, use of large bicycles (more than 250CC displacement) for leisure purpose has also rapidly increased. Traffic crash data clearly shows the increasing trend in motorcycle crashes. The ratio of motorcycle involved crashes out of total has increased from 5.7% in 2005 to 8.3% in 2008, and similar trend can be found in fatalities ratio as well. In this study, we assess the level of risk when motorcycles operate on motorways by analyzing traffic rule violation ratio, lane change behaviour, driving speed behaviors of motorcycles in Uninterrupted Traffic Flow Facilities and using PC-CRASH simulation we also calculate car shock impulses occurred when an accident happens. Analysis result shows that the motorcycle is different from the car in terms of lane change timing and average speed, and also shows motorcycle drivers tends to conduct more improper driving behavior particularly when traffic is congested. The results from this study could be usefully applied when the law enforcement agent decides whether bicycles shall be allowed to use motorways. The result could be also utilized as fundamental information for further study of bicycles' driving behavior.

• Korean Journal of Childcare and Education
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• v.9 no.6
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• pp.197-221
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• 2013

The purpose of this study was to examine the relationship between the child care support policies and the birth rate in 33 OECD countries. In the structural equation modelling, the birth rate was the dependent variable while the cash-support policies, the child-care facility service policies, and the tax benefits policies were the independent variables. The analysis showed that the most effective factor on the birth rate was the child-care facility service policies. Regarding the effectiveness of the policy expenses, the cash-support policies showed stable fluctuation of effectiveness according to the fluctuation of cash amount, the child-care facility service policies. In conclusion, in order to increase the effectiveness of the cash-support policies, the adequate cost calculation to decrease the parents' burden for child-bearing, re-allocation of budget, and support methods and timing should be continually discussed. In addition, for the better effectiveness of the facility service policies, more various, comprehensive and high-quality facility service policies that could balance home and work, should be implemented.

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.187-194
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• 2007

The purpose of this study is to determine the characteristics of ground reaction force(GRF) in golf swing for various slopes of flat lie and uphill lies of 5 and 10 degrees. Five right-handed professional golfers were selected for the experiment and the 7 iron club was used. We used four forceplates to measure GRF and synchronized with the three-dimensional motion analysis system. Results showed that slope did not affect the total time for golf swing, but the time until the impact had a tendency to slightly increase for the uphill lie(p<0.05). The medial-lateral GRF of the right foot increased toward the medial direction during back swing, but less increases were found with the angle of uphill lie(p<0.05). The GRF of the left foot increased rapidly toward the medial direction at the uncocking and the impact during down swing, but decreased with the increase in the angle of uphill lie(p<0.05). The anterior-posterior GRF of both feet showed almost the same for different slopes. With the slopes, the vertical GRF of the right foot increased, but the vertical GRF of left foot decreased(p<0.05). Uphill lies would have negative effect to provide the angular momentum during back swing, restricting pelvic and trunk rotations, and to provide the precise timing and strong power during down swing, limiting movements of body's center of mass. The present study could provide valuable information to quantitatively analyze the dynamics of golf swing. Further study would be required to understand detailed mechanism in golf swing under different conditions.

• Journal of Advanced Research in Ocean Engineering
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• v.3 no.4
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• pp.165-173
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• 2017

This study aims at validating simulations of the forced and freely vibrating cylinders at Reynolds number of approximately 500 in order to identify the capability of the CFD code, and to establish the analysis process of the vortex-induced vibration (VIV). The direct numerical and large eddy simulations were employed to resolve the various length scales of the vortices, and the morphing technique was used to consider a motion of the circular cylinder. For the forced vibration case, both in- and anti-phase VIV processes were observed regarding the frequency ratio. Namely, when the frequency ratio approaches to unity, the synchronization/lock-in process occurs, leading to substantial increases in drag and lift coefficients. This is strongly linked with the switch in timing of the vortex formation, and this physical tendency is consistent with that of Blackburn and Henderson (J. Fluid Mech., 1999, 385, 255-286) as well as force coefficients. For the free oscillation case, the mass and damping ratio of 50.8 and 0.0024 were considered based on the study of Blackburn et al. (J. Fluid Struct., 2000, 15, 481-488) to allow the direct comparison of simulation results. The simulation results for a peak amplitude of the cylinder and a shedding mode are reasonably comparable to that of Blackburn et al. (2000). Consequently, based on aforementioned results, it can be concluded that numerical methods were successfully validated and the calculation procedure was well established for VIV analysis with reasonable results.