• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.164-164
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• 2023

This study investigates the importance of flood-influencing factors on the accuracy of flood risk mapping using the integration of remote sensing-based and machine learning techniques. Here, the Extreme Gradient Boosting (XGBoost) and Random Forest (RF) algorithms integrated with GIS-based techniques were considered to develop and generate flood risk maps. For the study area of NAPA County in the United States, rainfall data from the 12 stations, Sentinel-1 SAR, and Sentinel-2 optical images were applied to extract 13 flood-influencing factors including altitude, aspect, slope, topographic wetness index, normalized difference vegetation index, stream power index, sediment transport index, land use/land cover, terrain roughness index, distance from the river, soil, rainfall, and geology. These 13 raster maps were used as input data for the XGBoost and RF algorithms for modeling flood-prone areas using ArcGIS, Python, and R. As results, it indicates that XGBoost showed better performance than RF in modeling flood-prone areas with an ROC of 97.45%, Kappa of 93.65%, and accuracy score of 96.83% compared to RF's 82.21%, 70.54%, and 88%, respectively. In conclusion, XGBoost is more efficient than RF for flood risk mapping and can be potentially utilized for flood mitigation strategies. It should be noted that all flood influencing factors had a positive effect, but altitude, slope, and rainfall were the most influential features in modeling flood risk maps using XGBoost.

• Preventive Nutrition and Food Science
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• v.7 no.1
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• pp.88-94
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• 2002

The purpose of this study was to identify factors influencing the consumption of calcium-rich foods among adolescents. A total of 96 adolescents divided into twelve focus groups were investigated during April to May 2000 in Busan. Focus group discussions were audio-taped, transcribed and analyzed using a grounded theory approach. Key factors influencing the consumption of calcium-rich foods were taste, food type, body image, and family. Motivators among the factors were taste, flood type, body image, health, family and perception, and barriers were taste, flood type, location, friends, price, weather and lactose intolerance. Taste, flood type, location and weather were found to be both motivators and barriers of consumption of calcium-rich floods according to circumstances. Some of these factors varied in importance by gender and age. Younger adolescents were more strongly influenced by taste and family than older ones. Older adolescents were strongly influenced by body image, convenience and perception. These findings could be used as a guideline for adolescents to consume calcium-rich foods.

• Proceedings of the Korea Water Resources Association Conference
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• 2002.05a
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• pp.65-73
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• 2002

Weather Radar have played an important role in both precipitation observation and hydrological operations over several countries and evaluated its efficient and necessities for the developed flood management and control. This paper describe the factors influencing the design the hydrological radar network in Korea and develop Hydrological Radar Network Simulation Model (HRNSM) based on GIS and UI system. Moreover, the methodologies for geographical and hydrological feasibility analysis for radar network were provided in detail manner.

• Research in Community and Public Health Nursing
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• v.15 no.1
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• pp.145-154
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• 2004

Purpose: This study was performed to identify the extent of flood damage, the quality of life(QOL) and their relationships to flood victims. Method: The subjects of this study were 248(men 100, women 148) who live around seven areas in K province impacted by Typhoon Rusa. Data was collected between February 25 and March 21, 2003 by structured questionnaires. The instruments were composed of two parts. The extent of flood damage were the impacts of daily living by revised from Ginexi et aI.(2000). QOL was used to WHOQOL BREF Korean Version by Min et al.(2002). The SPSS program was used for its descriptive, reliability, and correlation analysis. Result: The means of the extent of flood damage were: daily living 1.88, economy 4.60, and health 3.75. The mean of total QOL was 2.95: social domain 3.29, overall satisfaction 3.09, physical domain 3.06, psychological domain 2.95, and environmental domain 2.68. The negative correlations were between the Impact of daily living and Total QOL(r=-.143, p<.05), Physical QOL(r=-.220, p<.01) and Overall satisfaction (r=-141, p<.05). Conclusion: This study has learned that the impact of the flood had negative effects on the flood victims quality of life, and the difficulties they faced in their daily lives. Further research will be needed to explore influencing factors on QOL in disaster victims.

• 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 the Korea Fashion and Costume Design Association
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• v.14 no.3
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• pp.11-22
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• 2012

As the consuming pattern is changing with the expansion of Internet use and the development of communication technology, Internet shopping market is getting bigger and bigger. By product group, clothing and fashion related products occupy the biggest share. Accordingly, in this study it was tried to identify the effects of Internet utilization capability that enables consumers to search for the information that they need in this information flood, variety pursuit trend and product review accommodation status on shopping value, and to analyze the effects of the shopping value on the purchase behavior in online shopping malls. When factor analysis is nude on Internet use level, it was found that Factor 1 was 'Flow Experience,' Factor 2 'Internet Use Capability,' and Factor 3 'Internet Challenge Desire.' When factor analysis is made on Diversity Pursuit Propensity, it was found that Factor 1 was 'Site Diversity Pursuit Propensity,' Factor 2 'Brand Diversity Pursuit Propensity,' and Factor 3 'Brand Value Pursuit Propensity.' When factor analysis is nude on Product Review Accommodation Propensity, it was found that Factor 1 was 'Product Information Provision Propensity,' and Factor 2 'Product Information Receiving Propensity.' Except Internet Use Capability and Product Information Provision Propensity, all other factors showed high correlation. The factor influencing the entertainment value most was Internet challenge desire, while that influencing the practical value most was flow experience. When the effects of the entertainment value and the practical value on product purchase were analyzed, it was found that both of entertainment value and the practical value influenced product purchase and the practical value influenced the product purchase more than the entertainment value.

• Ecology and Resilient Infrastructure
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• v.7 no.4
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• pp.336-344
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• 2020

The prediction and evaluation of driftwood accumulation around river-crossing structures are essential because driftwood accumulation increases during flood disasters. In this study, the driftwood accumulation and behavior around bridge piers were evaluated via a numerical model that could be employed to analyze three-dimensional turbulent flow and driftwood motion. The moving particle semi-implicit-based model for driftwood motion was sensitive to the number of spheres. The numerical results showed that the approach velocity and the ratio of driftwood length to pier width were the key factors influencing driftwood accumulation, whereas the driftwood density had only a minor influence. Overall, it is expected that this study will contribute to the development of improved risk evaluation indexes for assessing driftwood accumulation around river-crossing structures.

• Water for future
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• v.28 no.3
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• pp.197-204
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• 1995

The runoff from an urban catchment is increased because of the gravitation of the population towards cities. For this reason, water level increment in confluence area makes it impossible to drain internal water and thus produces flood out in upstream areas. In this study, flow variations of main channel are measured which is caused by combining storm sewer into main channel in small watershed. Depth increment in main stream is analyzed due to flowrate and slope in main channel and flowrate, slope is getting steeper, and also due to low flowrate in main stream and high flowrate in tributrary channel. For the degree of confluence, depth ratio decreases when the degree is getting small. As mentioned above, main factors influencing the depth ratio increment of confluence channel are in the order of the degree of confluence, and the flowrate of tributary channel and main channel.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.575-575
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• 2016

홍수로 인한 주거건물의 경제적 피해는 침수심, 침수기간, 유속 등의 재난인자와 제내지에 노출된 사회 경제적 인자들 간의 복합적인 작용으로 발생하지만, 다차원홍수피해산정법을 비롯한 대부분의 모형에서는 침수심 만을 고려하고 있다. 최근 국외에서는 홍수피해와 영향인자 간의 관계를 규명하여 홍수피해액 평가 시 침수심 외 중요한 기타 인자를 고려하는 연구가 시도된 바 있으나, 국내에서는 이것과 관련한 연구가 그동안 거의 진행된 바 없다. 이에 본 연구에서는 주거건물을 대상으로 홍수피해 영향인자를 규명하고자 과거 피해지역을 대상으로 설문조사를 시행하여 자료를 수집하였으며, 설문조사에 앞서 사전 문헌연구를 바탕으로 수리/수문학적 인자, 건물특성인자, 예방인자, 조기경보/조치인자, 사회 경제적인자, 피해인자로 설문항목을 크게 구분하여 설문지를 설계하였다. 설문조사는 2014년 8월에 광범위하게 피해가 발생한 부산광역시를 대상으로 1대1면접조사 방식으로 진행하였으며, 수집된 자료로부터 상관분석, 데이터마이닝 등의 통계적 분석을 통해 침수심 외 몇몇 중요한 피해액 영향인자를 확인할 수 있었다. 본 연구를 통해 평가된 홍수피해 영향인자는 향후 홍수피해평가 모델을 개발하거나 홍수피해저감을 위한 세부적인 계획에 기여할 것으로 기대된다.

• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.399-405
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• 2010

In order to quantify removal efficiency of Cryptosporidium in water treatment process and evaluate factors influencing removal efficiency of Cryptosporidium in each step of water treatment process, large pilot plant system ($100m^3/day$) and Cryptracer, surrogate of Cryptosporidium, were used. The removal efficiency of Cryptracer was around 0.8~1 log in coagulation process and 3.3~4.8 log in sand filtration process under ordinary environmental conditions. Factors influenced removal efficiency of Cryptracer were high fluctuate turbidity and water temperature. High fluctuate turbidity made difficult to adjust optimum PAC concentration, caused to drop removal efficiency of coagulation process (0.5 log). Inadequate coagulation process influenced to sand filtration process (2.1 log), caused to decline of removal efficiency in the whole process (2.6 log). Low temperature below $2^{\circ}C$ also influenced coagulation process (0.6 log). Therefore, It is shown that careful attention in the control of Cryptosporidium is needed in flood period, when high fluctuate turbidity would be, and winter period of low temperature.