• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.2
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• pp.81-90
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• 2017

Recent floodplain data are important for river master plan, storm and flood damage reduction comprehensive plan and pre-disaster impact assessment. Hazard map, base of floodplain data, is being emphasized as important method of non-structural flood prevention and consist of inundation trace map, inundation expected map and hazard information map. Inundation trace map describes distribution of area that damaged from typhoons, heavy rain and tsunamis and includes identified flood level, flood depth and flood time from flooding area. However due to lack of these data by local government, which are foundational and supposed to be well prepared nationwide, having hard time for making inundation trace map or hazard information map. To overcome this problem, time consumption and budget reduction is required through various research. From this study, DEM (Digital Elevation Model) from image material from UAVS (Unmanned Aerial Vehicle System) and numeric geographic map from National Geographic Information Institute are used for calculating flooding damaged area and compared with inundation trace map. As results, inundation trace map DEM based on image material from UAVS had better accuracy than that used DEM based on numeric geographic map. And making hazard map could be easier and more accurate by utilizing image material from UAVS than before.

• The Korean Journal of Applied Statistics
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• v.34 no.6
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• pp.957-968
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• 2021

Inverse censoring probability weighting (ICPW) is a popular technique in survival data analysis. In applications of the ICPW technique such as the censored regression, it is crucial to accurately estimate the censoring probability. A simulation study is undertaken in this article to see how censoring probability estimate influences model performance in censored regression using the ICPW scheme. We compare three censoring probability estimators, including Kaplan-Meier (KM) estimator, Cox proportional hazard model estimator, and local KM estimator. For the local KM estimator, we propose to reduce the predictor dimension to avoid the curse of dimensionality and consider two popular dimension reduction tools: principal component analysis and sliced inverse regression. Finally, we found that the Cox proportional hazard model estimator shows the best performance as a censoring probability estimator in both mean and median censored regressions.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.4
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• pp.31-38
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• 2008

Under the recent situation that there increase the efforts to facilitate DFS(driver feedback sign) in school zones and children's protection areas caused by severity of traffic impact on children, the current study aims at predictively evaluating how and to what extent the reduced car speed is influential to the reduction of traffic accidents in elementary schools located in Buchon city by analyzing the velocity variation before and after DFS installation including its reduction ratio in traffic accidents as well as related literature survey. It, furthermore, aims at identifying applicable effectiveness in DFS operation for elementary schoolers in Buchon based on the data collected.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.123-133
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• 2010

Due to climate change and difficulty in construction of large dam, it is on the increase to use small hydraulic facilities such as washland for the flood control purpose. Since there can be many potential locations for washland in a basin, it is important for determination of optimal location to calculate flood reduction effect of washlands substantially and exactly. In this study, a new scheme to increase flood reduction effect of washlands is suggested. Suggested scheme uses sensitivity analysis of flood reduction effect depending on washland characteristics such as storage volume, spillway elevation and spillway width. The characteristics of the washland is determined by results of sensitivity analysis to maximize flood reduction effect at basin outlet and downstream of a washland. The methodology is applied to Anseong river basin to show its applicability and applied result is compared with those of another studies.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.133-141
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• 2011

Urban development of basin causes increasing runoff volume and peak flowrate and shortening in time of concentration, which may cause frequent flooding downstream. An infiltration facilities are operated as a method of reducing flood discharge of urban rivers and peak flowrate. There are various types of infiltration facilities like infiltration trench and porous pavement. In this study, runoff reduction effect due to installation of infiltration facilities are performed and focused on $0.18km^2$ residential area of Ok-kye dong and $0.67km^2$ industrial area of Gong-dan dong in Gumi City. The analysis is fulfilled with comparison of total runoff volume and runoff reduction volume by using the WinSLAMM and the relation equation between area ratio of infiltration facilities and ratio of runoff reduction are derived and peak flow reduction effect for installation of infiltration facilities is analyzed.

• Journal of Industrial Technology
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• v.33 no.A
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• pp.3-8
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• 2013

Reduction of risk plays a pivotal role in the development of medical instruments. A hyperbaric oxygen chamber, as a medical device, is known to help medical therapy for diversity of diseases through provision of high purity oxygen. The use of hyperbaric oxygen is expected to increase in the future and study to rigorously examine reliability and safety is needed. We have performed risk assessment for a newly developed hyperbaric oxygen chamber in this study. We first briefly discussed the system structure and concept of risk assessment for the study. Based on the hazards identified, we performed preliminary hazard analysis for the chamber.

• 대한예방의학회:학술대회논문집
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• 1994.02a
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• pp.651-657
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• 1994

To assess quantitatively the association between benzene exposure and leukemia, we examined the mortality rate of a cohort with occupational exposure to benzene. Cumulative exposure for each cohort member was estimated from historical air-sampling data and, when no sampling data existed, from interpolation on the basis of existing data. The overall standardized mortality ratio (a measure of relative risk multiplied by 100) for leukemia was 337 (95 percent confidence interval, 154 to 641), and that for multiple myeloma was 409 (95 percent confidence interval, 110 to 1047). With stratification according to levels of cumulative exposure, the standardized mortality ratios for leukemia increased from 109 to 322, 1186, and 6637 with increases in cumulative benzene exposure from less than 40 parts per million-years (ppm-years), to 40 to 199, 200 to 399, and 400 or more. respectively. A cumulative benzene exposure of 400 ppm years is equivalent to a mean annual exposure of 10 ppm over a 40-year working lifetime; 10 ppm is the currently enforceable standard in the United States for occupational exposure to benzene. To examine the shape of the exposure-response relation, we performed a conditional logistic-regression analysis, in which 10 controls were matched to each cohort member with leukemia. From this model, it can be calculated that protection from benzene induced leukemia would increase exponentially with any reduction in the permissible exposure limit.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.3
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• pp.109-118
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• 2010

This study quantified the flood reduction effect of small stormwater detention facilities by the NRCS curve number. The modified rational equation was used to calculate the inflow volume into the detention facilities. The NRCS curve number in the cases w/ and w/o storage facility was calculated with respect to the rainfall characteristics(rainfall frequency, duration) and the size of storage facilities. Finally, diagrams showing the curve number reduction rate versus the size of storage facility were developed. The diagrams can be used to evaluate the flood reduction effect of storage facility reasonably and efficiently when estimating the optimal location and size of storage facility. The results based on the methodology propsed in this study were also compared with those of previous study for their validation.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.145-150
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• 2009

Because it is difficult to install new large hydraulic structure, washland is considered as alternatives of hydraulic facility. As flood reduction effect of washland is dependent on flood, hydrograph, capacity of washland and spillway height, applying adequate spillway height is very important to maximize flood reduction effect of washland. In this study, effect of variation of spillway height on flood reduction effect of washlands is analyzed. The existing model developed to make decision for optimal location of washland using flood reduction effect as evaluation function and location of washland as decision variable was revised for this purpose. The spillway height of washland is added as decision variable and revised model finally give optimal location and spillway height of washland as result. The developed model has been applied to the Ansung River basin and application result was compared with that of existing model. The application result shows that developed model can give more efficient result than existing model.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.259-262
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• 2007

In our country it develop damage reduction and prediction technology for prevention the danger of the rockfall and landslide which is repeated yearly. And it constructs integrated and efficient the misfortune management system it will be able to manage. So we will accomplish aims that is the rockfall and landslide damage occurrence reduction.