• Journal of Korea Water Resources Association
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• v.51 no.6
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• pp.481-490
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• 2018

Recently, the spatiotemporal patterns of flood disasters have become more complex and unpredictable due to climate change. Flood hazard map including information on flood risk level has been widely used as an unstructured measure against flooding damages. In order to product a high-precision flood hazard map by combination of hydrologic and hydraulic modeling, huge digital information such as topography, geology, climate, landuse and various database related to social economic are required. However, in some areas, especially in developing countries, flood hazard mapping is difficult or impossible and its accuracy is insufficient because such data is lacking or inaccessible. Therefore, this study suggests a method to delineate large scale flood-prone area based on topographic factors produced by linear binary classifier and ROC (Receiver Operation Characteristics) using globally-available geographic data such as ASTER or SRTM. We applied the proposed methodology to five different countries: North Korea Bangladesh, Indonesia, Thailand and Myanmar. The results show that model performances on flood area detection ranges from 38% (Bangladesh) to 78% (Thailand). The flood-prone area detection based on the topographical factors has a great advantage in order to easily distinguish the large-scale inundation-potent area using only digital elevation model (DEM) for ungauged watersheds.

• Journal of Wetlands Research
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• v.13 no.1
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• pp.1-11
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• 2011

A chronic drought stress has been imposed during non-rainy season(from winter to spring) since 1990s. We faced the most significant water crisis in 2001, and the drought was characterized by sultry weather and severe drought on a national scale. It has been widely acknowledged that the drought related damage is 2-3 times serious than floods. In the list of the world's largest natural disaster compiled by NOAA, 4 of the top 5 disasters are droughts. And according to the analysis from the NDMC report, the drought has the highest annual average damage among all the disasters. There was a very serious impact on the economic such as rising consumer price during the 2001 spring drought in Korea. There has been flood prevention measures implemented at national-level but for mitigation of droughts, there are only plans aimed at emergency (short-term) restoration rather than the comprehensive preventive measures. In addition, there is a lack of a clear set of indicators to express drought situation objectively, and therefore it is important and urgent to begin a systematic study. In this study, a nonstationary downscaling model using RCM based climate change scenario was first applied to simulate precipitation, and the simulated precipitation data was used to derive Standardized Precipitation Index (SPI). The SPI under climate change was used to evaluate the spatio-temporal variability of drought through principal component analysis at three different time scales which are 2015, 2045 and 2075. It was found that spatio-temporal variability is likely to modulate with climate change.

• Journal of Korea Water Resources Association
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• v.48 no.3
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• pp.149-158
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• 2015

It is well known that emergency outlet works have to be provided for the safety of dams. However, concept of emergency outlet works did not applied for the design of the most dams in Korea. Korean design standard for low-level outlet works does not provide enough design criteria which could be used in design of emergency outlet works. In this research, as-built status and hydraulic design criteria of outlet works, such as drawdown rate or hydraulic pressure due to the impounded water depth, were examined. Another relationship between drawdown rate and the dam slope stability was also examined with SEEP model. It was found that 25% reduction of impounded water depth decreases the pressure forces about 50%. Therefore, outlet works should be designed to drawdown properly at the beginning of the emergency. Seepage analysis of dam bodies showed that most of Korean dams could safely stand for 1m/day drawdown rate. Higher drawdown rate could result high discharge so the drawdown rate must be related with the flood risk of downstream. Finally, multi-stage design was recommended that faster discharge for the initial 25% of water depth in 7-10 days than the rest of it in 1-2 months.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.649-656
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• 2016

This study was a retrospective examination to identify the association of postoperative delirium of the prognosis on following femur fracture surgery in elderly patients. Data was collected from the medical records of elderly patients (aged 65 years or older), who underwent femur fracture surgery from July 2010 to January 2014, following on 3-years in one university hospital. A total of 68 patients were involved. There were 31 cases (45.6%) with delirium and 37 cases (54.4%) without delirium. The participant's average age was 80.8 (patients with delirium), and 81.8 (delirium without patients) years of age, respectively, and most of them were female. There was no significant difference between the two groups. Taking five or more medications, serum creatinine level, and the total medical costs were significantly different in the delirium group and non-delirium group. In addition, the proportional hazard model of Cox to determine the predictors for the major clinical outcome occurring after surgery revealed delirium, five or more multi-drug use, and an experience of transfusion to be significant predictors. In conclusion, postoperative delirium in the elderly undergoing femur fracture surgery can have a negative clinical outcome in patients and caregivers. Therefore, a preoperative evaluation and management of the risk factors will be necessary.

• The Korean Journal of Financial Management
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• v.22 no.2
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• pp.189-212
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• 2005

This study examines the interactions between KTB spot and futures markets using the daily prices from March 4, 2002 to January 31, 2005. We use Granger causality test, impulse Response Analysis and Variance Decomposition through vector autoregressive analysis (VAR). However, considering the long-term relationships between the level variables of KTB spot and futures, we introduced Vector Error Correction Model. The main results are as follows. According to the results of Granger-causality test and impulse response analysis, we find that the yields of KTB forward have a great influence on the change of KTB spot but not vice versa. In terms of volatility analysis, there is no inter-dependence between KTB forward and spot markets. In the variance decomposition analysis we find that the short-term KTB forward has much more impact on the KTB spot market than the long-term KTB forward does. We think these results are meaningful for bond investors who are in charge of capital asset pricing valuation, risk management and international portfolio management.

• Journal of Distribution Research
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• v.12 no.3
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• pp.69-90
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• 2007

This study is set out to investigate the factors that influence customers' behavior of choice and switching between online and offline channels, separating the purchase decision into two stages, i.e., information search and purchase. Factors influencing channel choice are found to differ from stage to stage. The main results of this study are as follows. At the information search stage, customers' channel knowledge had impacts on the choice of the channel. Customers are more likely to visit offline bookstores when they have hedonic shopping orientation and higher involvement level with books. On the contrary, customers are more apt to search online when they have a lot of online shopping experiences. At the purchase stage, the results varied according to the search channel. When customers search for information online, the following variables lead to online purchases: online shopping experiences with books, price-focused shopping orientation, and time availability for shopping. Perceived risk made customers purchase offline even though they searched online. In case of offline searching, customers with more convenience-focused, hedonic-focused shopping orientation and less tim availability purchased offline.

• Journal of Korean society of Dental Hygiene
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• v.17 no.2
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• pp.181-191
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• 2017

Objectives: The objective of the study was to investigate the use of dental hygiene devices in Korean adolescents. Methods: The study subjects were 70,362 adolescents in 800 schools who completed the 2015 Korean Youth Risk Behavior Web-based survey. Dependent variables included usage of dental floss, interdental brushes and mouthwash solutions. Independent variables included demographic characteristics of the subjects, health state and behaviors, and oral health behaviors and experience of oral diseases. Results: The related factors of usage of dental hygiene devices included gender, where females showed higher usage (OR=1.10) compared to males, father and mother's level of education where usage was higher in above university graduates (OR=1.20, OR=1.14) compared to less than high school graduation, economic status where usage was higherin high and middle (OR=1.93, OR=1.26) compared to low, vigorous physical activity where usage was higher in those who responded yes (OR=1.35) compared to no, subjective weight recognition where usage was higher in normal (OR=1.07) compared to under weight, sleep time where usage was higher in enough (OR=1.12) compared to not enough, number of toothbrushing (day) where usage was higher in 2 times or over 3 times (OR=1.35, OR=1.75) compared to below 1, oral health education experience (OR=1.10), sealant experience (OR=1.17) and scaling experience (OR=1.45) where usage was higher in those who responded yes compared to no, school where usage was lower in high school (OR=0.64) compared to middle school, residential type where usage was lower in rural area (OR=0.74) compared to metropolitan area, living form where usage was lower in other (OR=0.77), compared to with family, smoking (OR=0.93), and alcohol drinking (OR=0.90) where usage was lower in those who engage in the activities compared to those who didn't, BMI where usage was lower in normal (OR=0.87) and over weight (OR=0.98) compared to under weight. Conclusions: To expand the use of dental hygiene devices in the adolescents, it is necessary to improve the continuing education program for need and motivation of dental hygiene device usage.

• Journal of the Society of Disaster Information
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• v.16 no.1
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• pp.155-162
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• 2020

Purpose: The purpose of study was to identify problems in disaster recovery resource management and operation through on-site investigation and utilize them as improvement proposal for disaster recovery resources management by local governments. Method: Areas with high natural and social disasters recorded in historical and yearly records of natural and social disasters, related books, and annual reports for 20 years were selected. The DRSS data of the selected local governments were analyzed and the reserve warehouse were selected for field survey. Result: It is analyzed that the current situation in the city hall and district offices is somewhat insufficient due to heavy work by the working-level officials of local governments on the storage of disaster recovery resources. The actual amount of stockpiles and DRSS data are somewhat different or missing because the input method and criteria are not clear at present when inputting the current data. Conclusion: To improve the management of the disaster recovery resource reserve, it is deemed that education of DRSS and training of best practices for the operation of disaster management resources are urgently needed, and that a systematic management of stockpiles using disaster prevention experts will be required.

• Korean Journal of Environmental Agriculture
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• v.35 no.1
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• pp.6-14
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• 2016

BACKGROUND: Residual organochlorine pesticides (OCPs) are chemical substances that persist in the environment, bioaccumulate through the food web, and pose a risk of causing adverse effect to human health and the environment. They were designated as persistent organic pollutants (POPs) by Stockholm Convention. Greenhouse strawberry is economic crop in agriculture, and its cultivation area and yield has been increased. Therefore, we tried to investigate the POPs residue in greenhouse soil and strawberry.METHODS AND RESULTS: Extraction and clean-up method for the quantitative analysis of OCPs was developed and validated by gas chromatography (GC) with electron capture detector (ECD). The clean-up method was established using the modified quick, easy, cheap, effective, rugged, and safe(QuEChERS) method for OCPs in soil and strawberry. Limit of quantitation (LOQ) and recovery rates of OCPs in greenhouse soil and strawberry were 0.9-6.0 and 0.6-0.9 μg/kg, 74.4-115.6 and 75.6-88.4%, respectively. The precision was reliable sincerelative standard deviation (RSD) percentage (0.5-3.7 and 2.9-5.2%) was below 20, which was the normal percent value. The residue of OCPs in greenhouse soil was analyzed by the developed method, and dieldrin, β-endosulfan and endosulfan sulfate were detected at 1.6-23, 2.2-28.4 and 1.8-118.6 μg/kg, respectively. Those in strawberry were not detected in all samples.CONCLUSION: Dieldrin, β-endosulfan and endosulfan sulfate in a part of investigated greenhouse soil were detected. But those were not detected in investigated greenhouse strawberry. These results showed that the residue in greenhouse soil were lower level than bioaccumulation occurring.

• Journal of Korean Foot and Ankle Society
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• v.17 no.1
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• pp.23-27
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• 2013

Purpose: The optimal management for ankle fracture in elderly patients remains controversial. This study was undertaken to review the results of surgical treatment of ankle fracture in the elderly and to compare with other studies. Materials and Methods: The participants in this study were 33 patients over the age of 65(average 71.5 years) who underwent surgical treatment of ankle fracture from January 2004 to December 2011. The study was a retrospective review of outcomes after open reduction and internal fixation (ORIF) of ankle fractures. To measure the clinical outcomes, we assessed postoperative complications, the pre- and post-operative mobility status, fracture union status, the time of fracture union and the AOFAS (American Orthopaedic Foot and Ankle Society) Ankle-Hindfoot scale. The level of patient satisfaction was also identified. Results: Delayed wound healing occurred in three patients(9.1%) but their wounds healed with repeated dressings without additional surgical treatment. Malunion occurred in one patient(3%). One patient(3%) had postoperative infection but healed with antibiotic treatment. 24 patients(96%) returned to preoperative mobility status. VAS score was lower than 2 in all patients. Bone union occurred with the 3.8 months (average months) after the surgery in all patients. Average AOFAS score was 87.4 and these were similar results as other studies of young patients. All patients were satisfied with surgical outcomes according to interviews. Conclusion: Surgical treatment of ankle fractures in the elderly can carry a significant risk of delayed wound healing and infection but incidence is relatively low. Internal fixation of ankle fractures in the elderly can be undertaken safely and the majority of patients can expect good outcome.