• Korea journal of population studies
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• v.31 no.1
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• pp.1-26
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• 2008

This research examines the effect of area level characteristics on individual health, particularly focusing on the vulnerable populations in Seoul. We consider adult individuals whose family income is under 1.5 million won, who are aged 65 and over, or who have neither spouse nor job but aged 40 and over as vulnerable populations. Using the 2005 Seoul Citizens' Health Interview Survey, we conducted multilevel analyses to simultaneously investigate the effect of area and individual level characteristics on health. Between-area variance of self-rated health status was greater for the elderly population than for all populations. Area material deprivation index and happiness index were associated with the self-rated health of economically disadvantaged populations. Vulnerable populations showed greater between-area variances in emotional health than the same for all populations. Area happiness index, material deprivation index, the proportion of households below poverty line and street safety showed statistically significant association with emotional health. The effect of area characteristics were particularly salient for the emotional health of elderly population and its between area variance was also notable.

• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.107-116
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• 2002

Crash Cushion is a kind of safety facilities on roadside which acts the role of absorbing impact energy when vehicles are driven out of normal route such as Gore area of freeway off ramp. Criteria for severity index considering accident occurrence possibility are needed to have strong effect on installing the facilities. However, present criteria for establishing crash cushion design do not include such processes. Therefore, the paper presents two kinds of study to develop criteria for severity index. First of all, development of accident forecasting model on freeway off ramp is presented. The module is a relationship between accidents and road environment by negative binomial distribution (NB) which is called to reflect very well quality of accidents at Gore of crash cushion installed freeway Secondly, freeway exiting behavior model is developed because the human factor is the most important one. However, many literatures have shown between road environment and accidents which are more quantitative than human factor. The study supposed advanced process steps on actual freeway and analysed correlation between variables and accidents. The criteria for severity index is presented to determine whether to install or not by benefit cost analysis for each module. The standard for severity index will help to determine whether to install the crash cushion or not and to estimate severity for freeway and off ramp.

• Journal of Korean Society of Transportation
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• v.31 no.1
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• pp.3-13
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• 2013

This paper reviews the characteristics of dilemma zone by analysing the influence exerted by actual location of intersection traffic signal on behaviour of drivers approaching signalized intersection in urban area. The analysis of approach speed was based upon a 'before and after' comparison, measured at three sites where the locations of traffic signals were changed. The study demonstrated that, when traffic signal changed to yellow, the scales of dilemma zone were narrowed in case of stopping cars by moving up the starting point of the dilemma zone due to lowered spot speed. On the other hand, in case of passing cars, the end points of dilemma zone were moved further out to the rear due to increased spot speed. Therefore, changing traffic signal locations could make an impact to increase intersection safety through reducing the scales of dilemma zone. This study also found that, in cases involving vehicles with similar approach speeds, spot speeds could be differentiated following the change of signal locations due to the fact that there can be greater differences in both braking point and deceleration rate. Thus, when considering the appropriate measuring of dilemma zone, 'spot speed' rather than 'approach speed' appeared to be more appropriate criterion.

• Journal of Korean Society of Transportation
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• v.35 no.3
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• pp.183-196
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• 2017

In this study, policy evaluation scheme was established to encourage the efficient implementation of EcoMobility which has been expanding gradually all around the world. A total of eight evaluation goals and 22 evaluation items are reviewed and suggested based on the three major evaluation categories of "Basic elements for EcoMobility", "Land use and transport system for EcoMobility", and "Implications and impact of EcoMobility". The results of this study are as follows: the result of AHP analysis which reflects only the hierarchical structure shows a high priority in "Elements for EcoMobility promotion", "Eco-fiendly transport infrastructure", and "Safety in transport". While in result of ANP which considered the elements' dependencies, "Eco-fiendly transport Services", "Welfare in transport", and "Environment by transport" have high weights and importances. In conclusion, this study would be useful to make reasonable judgment based on the analysis results of the two techniques in order to ensure reliability in evaluation of EcoMobility policy. Furthermore we have confirmed appropriate evaluation technique between AHP and ANP which is better to reflect the features of EcoMobility.

• Journal of Korean Society on Water Environment
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• v.34 no.4
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• pp.363-374
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• 2018

The Han River serves as an important water resource for the city of Seoul, Korea and in the neighboring metropolitan areas. From the Paldang dam to the Jamsil submerged weir, the 4 water intake stations that are located for the Seoul metropolitan population were under review in this study. Therefore the water quality management in this section is very important to monitor, analyze and review to rule out any safety concerns. In this study, a 3-D hydrodynamic model, EFDC (Environmental Fluid Dynamics Code), was applied to the downstream of the Paldang Dam in the Han River, which is about 23 km in length, to determine issues related to water resource management. The 3-D grid was composed of 2,168 horizontal grids and three vertical layers. In this case, the hydrodynamic model was calibrated and verified with an observed average daily water surface elevation, water temperature and flow rate data for 3 years (2013~2015). The developed EFDC model proved to reproduce the hydrodynamics of the Han River well. The composition ratios of the noted incoming flows at the monitored intake stations for 3 years and their flow patterns in the river were analyzed using the validated model. It was found that the flow of the Wangsuk Stream depended on the Paldnag dam discharge, and it was noted that the composition ratios of the stream at the intake stations changed accordingly. In a word, the Wangsuk Stream moved mainly along the right bank of the Han River under the condition of a normal dam flow. As can be seen, when the dam discharge rate was low, the incidence of lateral mixing was often seen. The scenario analyses were also conducted to predict the transport of conservative pollutants as in the case of a chemical spill accident. Generally speaking, when scenarios were applied, the arrival time and concentration of pollutants at each intake station was thus predicted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.408-417
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• 2017

This study was conducted to examine the influence of the nurse staffing level on the level of in-hospital death and infection in cancer patients who received surgery. Secondary data were used and the subjects of this study were 24,510 patients who received surgery for six types of cancer with a high postoperative mortality rate in the first half of 2012 at 260 hospitals. Simple logistic and GEE multiple logistic regression analyses were used. After adjusting for the patient and hospital characteristics, a greater likelihood of dying was found in the nurse staffing level 2-3 group (odds ratio [OR], 1.46; 95% confidence interval [CI], 1.00-2.11) and in the level 6-7 group (OR, 3.28; 95% CI, 1.87-5.74) compared to the level 0-1 group. The likelihood of in-hospital infection increased with each additional bed per nurse, being 6.63 times higher (95% CI, 3.00-14.62) in the level 2-3 group, 5.79 times higher (95% CI, 1.88-17.78) in the level 4-5 group, and 8.4 times higher (95% CI, 1.82-38.84) in the level 6-7 group, as compared to the level 0-1 group. A lower nurse staffing level was associated with higher in-hospital death and infection levels. This shows that an appropriate nurse staffing level is associated with superior postoperative cancer patient outcomes. Policies for providing adequate nurse staffing should be maintained for the sake of ensuring improved care quality and patient safety.

• Journal of the Korean Geotechnical Society
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• v.33 no.9
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• pp.5-22
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• 2017

The procedure that combines the result of infiltration analysis into stability analysis based on the limit equilibrium method is widely used to evaluate the impact of rainfall infiltration on slope stability. Accurate prediction of rainfall infiltration is essential to the prediction of landslides caused by rainfall, requires to obtain accurate unsaturated hydraulic properties of the soil. Among the unsaturated hydraulic characteristics of the soil, the importance of the soil-water characteristic curve describing the retained water characteristics of the soil is relatively well known and the measurement by test method to obtain the SWCC is gradually increasing. However, it takes a lot of time and expenses to experimentally measure the unsaturated conductivity characteristics of the soil. Therefore, it is common practice to estimate the hydraulic conductivity function from the SWCC. Although it is widely known that the SWCC has a great influence on rainfall infiltration, studies on the effect of the hydraulic conductivity function estimated from the SWCC on rainfall infiltration are very limited. In this study, we explained how the estimation model of the hydraulic conductivity function affects rainfall infiltration and slope stability analysis. To this end, one-dimensional infiltration analysis and slope stability analysis were conducted by using the data on the SWCC of weathered granite soil widely distributed in Korea. The applicability of each estimation model is discussed through review of the analysis results.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.4
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• pp.73-85
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• 2014

Approaching to aging society with increasing transportation vulnerable, most developed countries has positively promote low-floor bus. Such circumstance in Korea has plan to introduce low-floor bus to intra-city bus system which accounted for 30 percent of total number of buses however there is no specific operating plan for this matter. According to the revealed preference study on bus service, the study shows that the efficiency of low-floor is relatively low than that of other buses, therefore, it is necessary to establish feasible plan for bus route selection. Thus, this study is to conduct research on analyzing trip characteristics of transportation vulnerable and establish bus route selection measures for low-floor bus. The result from the survey in Jeollabuk-do Province reveals that the trip purpose of transportation vulnerable is mainly for welfare and medical service, which was made less than 6 times a week. Futhermore, 37.6 percent of transportation vulnerable use buses, thus, it is essential to improve its service quality for enhancing user's convenience and safety. In that transportation vulnerable O-D needs to be established and forecasts future demand for selecting optimal bus route. According to the estimation, route passing through densely populated areas with transportation vulnerable should take the first priority, city circular and other route would be next. Moreover, it is economically efficient that areas populated more than 200,000 with fixed route and less than 200,000 with limited route responsive to demands would be feasible plans. This study will have greater an impact on transportation planning and further research on transportation vulnerable.

• Journal of Trauma and Injury
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• v.28 no.2
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• pp.60-66
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• 2015

Purpose: Cultivator accidents are frequent and often lead to abdomino-perineal organ injury and, if severe, to death. This study presents the clinical characteristics, outcomes, and factors associated with mortality in patients who sustained an abdomino-perineal organ injury in cultivator accidents. Methods: We retrospectively analyzed the records of 53 patients who visited the emergency department of a tertiary hospital with abdomino-perineal organ injuries caused in cultivator accidents from April 2005 to March 2010. Results: All 53 patients had visited other medical institutions before visiting our hospital. Their mean age was $64.0{\pm}11.1$ (range, 20-80) years and 32 (60.4%) patients were 65 or older. The male-to-female ratio was 46:7. The chief complaint was abdominal pain (38 cases, 71.7%). The 53 patients included 41 cultivator operators (77.4%), 11 passengers (20.8%), and 1 passerby (1.9%). The causes of the injuries included a direct impact of the handlebar in 20 cases (37.7%), a rollover in 21 cases (39.6%), a fall in 10 cases (18.9%), and a wheel in two cases (3.8%). Several of the 53 patients had injuries to multiple abdomino-perineal organs, and the injured organs included the liver (23 cases, 26.4%), spleen (16 cases, 18.4%), pancreas (7 cases, 8.0%), small bowel (7 cases, 8.0%), mesentery (6 cases, 6.9%), adrenal gland (5 cases, 5.8%), and other organs. According to the abbreviated injury scale (AIS) dictionary, a thoracic injury was the most frequent co-injury (33 of 53 cases, 62.3%). Abdomino-perineal surgery was performed in 31 cases (58.8%) and angio-embolization was performed for six liver and two kidney injuries. Thirteen patients died (24.5%); all were males. The Injury Severity Scale (ISS) was lower in the survivors ($17.8{\pm}8.5$ vs. $27.0{\pm}16.0$; p=0.010). Conclusion: With the aging of agricultural workers, safety education programs should be implemented. Furthermore, the patient transfer system in agricultural areas must be improved.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.801-810
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• 2019

This study analyzes the impact on geomorphic changes downstream due to alternate bars developed weir upstream through laboratory experiments. The disturbance, such as a spur in the side wall, of the flow at the inlet of the channel triggers the development of alternate bar upstream at the beginning of the experiment, and gradually moved downstream with keeping their shapes over time. The bed in the downstream of weir in the mid of channel scoured due to the scarcity of sediment inflow because weir upstream traps it. Moreover, bar migration speed decreases as the bars approaches to the weir with time. However, as time increases, the alternate bars upstream migrate over the weir, and sediment in the eroded bed of the weir downstream are deposited. The phase of the bar upstream changes oppositely after passing through the weir. The phase of the bar downstream changes rapidly as the shape of alternate bar is clear upstream, which is affected by the strong disturbance. The phase of bar changes, and the bar migration speed decreases gradually with time, and finally stopped due to forcing effects on the bar by the disturbance. The faster the reaction of alternate bar with a long spur, the larger the bar height formed downstream and the shorter the bar length. This means that the larger the forcing effect of bar, the more it affects the bar migration. In addition, although the size of the alternate bar increases over time, the bar doesn't migrate downstream and a forced bar is generated.