• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.5
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• pp.30-42
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• 2023

Various studies have been conducted using microtraffic simulation (VISSIM) to analyze the safety of traffic flow when introducing autonomous vehicles. However, no studies have analyzed traffic safety in mixed traffic while considering the driving behavior of general vehicles as a parameter in VISSIM. Therefore, the aim of this study was to optimize the input variables of VISSIM for non-autonomous vehicles through genetic algorithms to obtain realistic behavior. A traffic safety analysis was then performed according to the penetration rate of autonomous vehicles. In a 640 meter section of US highway I-101, the number of conflicts was analyzed when the trailing vehicle was a non-autonomous vehicle. The total number of conflicts increased until the proportion of autonomous vehicles exceeded 20%, and the number of conflicts decreased continuously after exceeding 20%. The number of conflicts between non-autonomous vehicles and autonomous vehicles increased with proportions of autonomous vehicles of up to 60%. However, there was a limitation in that the driving behavior of autonomous vehicles was based on the results of the literature and did not represent actual driving behavior. Therefore, for a more accurate analysis, future studies should reflect the actual driving behavior of autonomous vehicles.

• Land and Housing Review
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• v.14 no.4
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• pp.47-62
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• 2023

Using the dynamic panel model, this study investigates rent determinants for small and medium-sized office buildings in Korea's CBD and Gangnam areas, key business districts. The results reveal that rents for small and medium-sized office buildings in CBD and Gangnam areas are influenced by macroeconomic fluctuations and characteristics of buildings and locations, suggesting a market with both spatial consumer and investment goods attributes. There are several investment implications as follows. First, even if the location in the CBD area is advantageous, the practical limitations in renovating aging small and medium-sized office buildings must be taken into account when investing. Second, parking conditions are a key factor influencing rent prices in CBD areas, so evaluating the parking facilities and improvement potential of small and medium-sized office buildings is essential for investors. Finally, due to the high sensitivity of Gangnam's small and medium-sized office market to macroeconomic trends, it's vital to prioritize monetary policy shifts as a key factor in investment decisions.

• Pediatric Infection and Vaccine
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• v.21 no.3
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• pp.174-180
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• 2014

Purpose: This study was performed to assess the clinical and epidemiological changes after the introduction of the rotavirus vaccine in Korea, as well as to determine the efficacy of the rotavirus vaccine among hospitalized rotaviral gastroenteritis patients over the past two years. Methods: We analyzed yearly and seasonal patterns of 1,165 inpatients who were hospitalized for rotaviral gastroenteritis under the age of 5 years between 2006 and 2013. We also conducted a survey among 460 gastroenteritis patients who were hospitalized between 2012 and 2013 regarding the rotavirus vaccination and the symptoms of gastroenteritis. Among those individuals surveyed, clinical indices were analyzed for 124 patients who were tested positive for the rotavirus antigen. Results: The incidence of Rotaviral gastroenteritis have decreased significantly by year 2010. After the introduction and widespread dissemination of the rotavirus vaccine, the onset of the disease and the seasonal peak have been delayed. Overall, the vaccinated group showed a lower rate of positivity than the unvaccinated group. Among the hospitalized rotaviral gastroenteritis patients, the vaccinated group had a shorter hospitalization period, less severe clinical symptoms of gastroenteritis, and better laboratory test results. Conclusions: After introduction of the rotavirus vaccine in Korea, there were two main trends observed: 1) the overall level of disease incidence was reduced; 2) the severity of rotaviral gastroenteritis cases also decreased. Based on this data, more children should receive vaccination in order to prevent the rotavirus infection and decrease the severity of rotaviral gastroenteritis.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.3
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• pp.39-53
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• 2014

The Korean population is aging rapidly and a disproportionate share of older people(aged 65 and older) lives in rural areas. The rural population is aging more rapidly than the population in urban area. However, the majority of studies on aging population focuses on an urban area rather than a rural area. Rural areas have been alienated from the priority of the national policy. For these reasons, this study is to show the level of population aging and to analyze the spatial spillover patterns of aging population in rural areas for the establishment of localized policy on population aging. The main findings of this study can be summarized as follows. First, the level of population aging varies in different localities such as socio-economic and locational characteristics. Secondly, there are distinct differences between hot spot region(clustering of high aging index) and cold spot region(clustering of low aging index) in spatio-temporal spillover patterns. This study intends to suggest an useful information to establish the area-specific policy on aging population through the results of analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6D
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• pp.779-784
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• 2011

Freeway FFS (Free-Flow Speed) under the state of LOS (Level of Service) A has been regarded as a homogeneous state to all levels of traffic volume. The features of low-density FFS is served as the basic data for a decision on limited maximal speed, accident analysis, simulation modeling etc. A few researches for the macroscopic characteristics of design and operation speed have been reported, and any study for the microscopic features of freeway free-flow speed under the state of low density has not been done. Therefore, the characteristics of low-density FFS according to the level of traffic volume (1-3 veh/30 sec) and daily hour periods (0-5, 6-8, 9-11, 12-19, 20-23) is microscopically analyzed in this study with huge volume and speed data. It was found that speed distributions are changed and show different behaviors under the conditions of traffic volume levels and daily time periods. V85s (85th percentile speed) at early morning and night periods decrease when levels of traffic volume increase, whereas V85s at day time do not show considerable differences. Especially, FFSs of levels of traffic volume at early morning and night periods, despite low density, is analyzed as heterogeneity, but homogeneity at day time.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.4
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• pp.40-51
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• 2015

This study analysis traffic phase order alternatives to maximize throughput. According to theoretical analysis alternative2(EW: left turn after through, NS: through after left turn) and alternative5(EW: through after left turn, NS: left turn after through) can minimize the maximum delay. Both alternatives split the phase that have the same destination link under the whole cycle length. This shows that phase order alternative can effect to the fully saturated intersection. In side of simulation analysis by microscopic traffic simulator PTV VISSIM F 7.0, each phase order alternatives can't effect throughput under the non saturated condition. However under the saturated condition, the average controlled delay of the intersection has been changed by phase order alternatives. The simulation analysis shows that alternative2 and alternative5 increase throughput 3.8% to 5.1% under the saturated condition.

• Korea journal of population studies
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• v.26 no.1
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• pp.171-194
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• 2003

The present study investigates the effects of lopsided regional policy and social prejudice on homeownership disparities by household's place of birth of household head in Seoul. The present study utilizes individual household-level census data (2% sample) to evaluate households' residential well-being denoted by homeownership status during the period of 1980-2000. Decomposition techniques based on tenure choice models were used to provide evidences of the home-ownership disparities caused by regional policy and prejudice. We found that households from Gangwon and Honam provinces represent a disproportionately small percentage of homeownership compared with those originated from other provinces. In the statistical analysis, the present study found that having controlled for the factors traditionally thought to influence households' choice of housing tenure, as well as other housing market characteristics in Seoul, place of birth has played a primary role in determining whether or not households become a homeowner. Most strikingly, while most of the disparity in homeownership ratios between households from Youngnam and households from Gangwon in the housing market is due to the endowment differences in human capitals they bring to the market, those between households from Youngnam and households from Honam is largely due to residual differences explained mainly by social discrimination and prejudice against people from Honam. The present study summarized that place of birth has played a primary role in determining whether or not households become a homeowner in Korea. The present study concluded with some policy issues relevant to this study and suggested some future studies.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.6
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• pp.182-194
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• 2017

Most of the drone (Unmanned Aerial Vehicle) research in terms of traffic management involves detecting and tracking roads or vehicles. The purpose of analyzing image footage in the transportation sector is to overcome the limitations of the existing traffic data collection system (vehicle detectors, DSRC, etc.). With regards to this, drones are the good alternatives. However, due to limitation in their maximum flight time, they are appropriate to use as a complementary rather than replacing the existing collection system. Therefore, further research is needed for utilizing drones for transportation analysis purpose. Traffic problems often arise from one particular section or a point that expands to the whole road network and drones can be fully utilized to analyze these particular sections. Based on the study on the uses of traffic survey analysis, this study is conducted by extracting traffic flow parameters from video images(range 800~1000m) of highway unit segments that were taken by drones. In addition, video images were taken at a high altitude with the development of imaging technologies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.294-299
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• 2019

Korean hospitals implement external quality assessment (EQA) schemes to improve the quality of clinical tests. However, smaller hospital do not implement EQA due to lack of appreciation and cost burdens. The purpose of this study was to analyze the results of EQA from the perspective of clinical chemistry carried out at a small-to-medium sized hospital (SMH) and to investigate factors influencing quality control. The medical institution concerned had performed EQA on 21 items annually for three years and had analyzed measurement methods, variation coefficients, and anomalous results as defined by the SMH. No significant change in test methods or variation coefficients, which exhibited a high level of variation, were observed for any test item over the 3-year period. The results obtained showed that anomalous test results were significantly more frequent when EQA was not conducted (p<0.05), internal quality control was not conducted daily (p<0.01), and when tests were less frequently performed (p<0.01). Small-to-medium sized hospitals need to be more aware of the benefits of EQA and provide tailored education to staff.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.5
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• pp.100-111
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• 2019

The existing selected station analysis (SSA) method analyzes the link transfer mode data between origin and destination of individuals passing through stations from a microscopic standpoint. As such, existing SSA is insufficient as it uses integrated analysis using macroscopic data such as subway lines. This research builds a line chain OD based on path search of individual passenger's movement through the subway, and explores means to utilize the findings. First, a method is proposed that searches the traversed subway path from the linked passage modes that the passenger uses and applies the results to SSA line analysis. Compared to the existing SSA, this method provides for analysis of commonly conflicting features such as the line on which the station is passed, and the stations included on the line thanks to the presence of complete information of the individual passenger's traversed path. It also allows for integrated observation of the line chain OD that approaches a certain station. For enhanced understanding, Seoul Metro Line 9 is used as a case study to demonstrate the integrated formulation concept of line chain OD centered around a certain station as well as the macroscopic features of the traversed path that approaches stations included on the line.