• Journal of the Economic Geographical Society of Korea
• /
• v.11 no.3
• /
• pp.459-475
• /
• 2008

This study analyzes the network structure of the Metropolitan Seoul subway system by applying complex network analysis methods. For the purpose, we construct the Metropolitan Seoul subway system as a network graph, and then calculate various indices introduced in complex network analysis. Structural characteristics of Metropolitan Seoul subway network are discussed by these indices. In particular, this study determines the shortest paths between nodes based on the weighted distance (physical and time distance) as well as topological network distance, since urban travel movements are more sensitive for them. We introduce an accessibility measurement based on the shortest distance both in terms of physical distance and network distance, and then compare the spatial structure between two. Accessibility levels of the system have been getting up overall, and thus the accessibility gaps have been getting lessen between center located subway stops and remote ones during the last 10 years. Passenger traffic volumes are explored from real passenger transaction databases by utilizing data mining techniques, and mapped by GIS. Clear differences reveal between the spatial patterns of real passenger flows and accessibility. That is, passenger flows of the Metropolitan Seoul subway system are related with population distribution and land use around subway stops as well as the accessibility supported by the subway network.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.9
• /
• pp.2216-2222
• /
• 2014

A recent trend of increasing container traffic volume using reefer container demands continuous management of reefer container in transit. However, reefer containers can only be monitored at terminal or in ship during marine transportation instead of throughout entire section. In the case of inland transportation section using truck or train, monitoring is not possible currently. The reason is because the reefer container monitoring method using PCT recommended by IMO and conventional monitoring methods using TCP/IP, RFID communication require establishing additional communication infrastructure. This paper will propose a new reefer container control device that not only solves these problems and monitors during inland transportation section but also controls reefer container. Using data port attached to every reefer container, the proposed device collects the information of reefer container and using M2M communication technology, it transmits information to server without the need to establish additional communication infrastructure. In addition, it can control the operational status of reefer container upon receiving control information set in server such as temperature of reefer container.

• Korean Journal of Environment and Ecology
• /
• v.35 no.2
• /
• pp.193-203
• /
• 2021

As endangered species are gradually increasing due to land development by humans, it is essential to secure sufficient protected areas (PAs) proactively. Therefore, this study checked priority conservation areas to select candidate PAs when considering the impact of land development. We determined the conservation priorities by analyzing four scenarios based on existing conservation areas and reflecting the development impact using MARXAN, the decision-making support software for the conservation plan. The development impact was derived using the developed area ratio, population density, road network system, and traffic volume. The conservation areas of endangered species were derived using the data of the appearance points of birds, mammals, and herptiles from the 3rd National Ecosystem Survey. These two factors were used as input data to map conservation priority areas with the machine learning-based optimization methodology. The result identified many non-PAs areas that were expected to play an important role conserving endangered species. When considering the land development impact, it was found that the areas with priority for conservation were fragmented. Even when both the development impact and existing PAs were considered, the priority was higher in areas from the current PAs because many road developments had already been completed around the current PAs. Therefore, it is necessary to consider areas other than the current PAs to protect endangered species and seek alternative measures to fragmented conservation priority areas.

• International Journal of Highway Engineering
• /
• v.11 no.4
• /
• pp.69-78
• /
• 2009

Korea has achieved significant economic growth with building the Gyeongbu Expressway. As the number of new road construction projects has decreased, it becomes more important to maintain optimal status of the current road networks. One of the best ways to accomplish it is weight enforcement as active control measure of traffic load. This study is to develop High-speed Weigh-in-motion System in order to enhance efficiency of weight enforcement, and to analyze patterns of overloaded trucks on highways through the system. Furthermore, it is to review possibilities of developing overweight control system with application of the HS-WIM system. The HS-WIM system developed by this study consists of two sets of an axle load sensor, a loop sensor and a wandering sensor on each lane. A wandering sensor detects whether a travelling vehicle is off the lane or not with the function of checking the location of tire imprint. The sensor of the WIM system has better function of classifying types of vehicles than other existing systems by detecting wheel distance and tire type such as single or dual tire. As a result, its measurement errors regarding 12 types of vehicle classification are very low, which is an advantage of the sensor. The verification tests of the system under all conditions showed that the mean measurement errors of axle weight and gross axle weight were within 15 percent and 7 percent respectively. According to the WIM rate standard of the COST-323, the WIM system of this study is ranked at B(10). It means the system is appropriate for the purpose of design, maintenance and valuation of road infrastructure. The WIM system in testing a 5-axle cargo truck, the most frequently overloaded vehicle among 12 types of vehicles, is ranked at A(5) which means the system is available to control overloaded vehicles. In this case, the measurement errors of axle load and gross axle load were within 8 percent and 5 percent respectively. Weight analysis of all types of vehicles on highways showed that the most frequently overloaded vehicles were type 5, 6, 7 and 12 among 12 vehicle types. As a result, it is necessary to use more effective overweight enforcement system for vehicles which are seriously overloaded due to their lift axles. Traffic volume data depending upon vehicle types is basic information for road design and construction, maintenance, analysis of traffic flow, road policies as well as research.

• Journal of Korean Society of Transportation
• /
• v.30 no.2
• /
• pp.101-116
• /
• 2012

Accident prediction models have been utilized to predict accident possibilities in existing or projected freeways and to evaluate programs or policies for improving safety. In this study, a traffic accident prediction model for freeways was developed for the above purposes. When selecting variables for the model, the highest priority was on the ease of both collecting data and applying them into the model. The dependent variable was set as the number of total accidents and the number of accidents including casualties in the unit of IC(or JCT). As a result, two models were developed; the overall accident model and the casualty-related accident model. The error structure adjusted to each model was the negative binomial distribution and the Poisson distribution, respectively. Among the two models, a more appropriate model was selected by statistical estimation. Major nine national freeways were selected and five-year dada of 2003~2007 were utilized. Explanatory variables should take on either a predictable value such as traffic volumes or a fixed value with respect to geometric conditions. As a result of the Maximum Likelihood estimation, significant variables of the overall accident model were found to be the link length between ICs(or JCTs), the daily volumes(AADT), and the ratio of bus volume to the number of curved segments between ICs(or JCTs). For the casualty-related accident model, the link length between ICs(or JCTs), the daily volumes(AADT), and the ratio of bus volumes had a significant impact on the accident. The likelihood ratio test was conducted to verify the spatial and temporal transferability for estimated parameters of each model. It was found that the overall accident model could be transferred only to the road with four or more than six lanes. On the other hand, the casualty-related accident model was transferrable to every road and every time period. In conclusion, the model developed in this study was able to be extended to various applications to establish future plans and evaluate policies.

• Journal of Intelligence and Information Systems
• /
• v.27 no.4
• /
• pp.23-48
• /
• 2021

The Korean economy has achieved continuous economic growth for the past several decades thanks to the government's export strategy policy. This increase in exports is playing a leading role in driving Korea's economic growth by improving economic efficiency, creating jobs, and promoting technology development. Traditionally, the main factors affecting Korea's exports can be found from two perspectives: economic factors and industrial structural factors. First, economic factors are related to exchange rates and global economic fluctuations. The impact of the exchange rate on Korea's exports depends on the exchange rate level and exchange rate volatility. Global economic fluctuations affect global import demand, which is an absolute factor influencing Korea's exports. Second, industrial structural factors are unique characteristics that occur depending on industries or products, such as slow international division of labor, increased domestic substitution of certain imported goods by China, and changes in overseas production patterns of major export industries. Looking at the most recent studies related to global exchanges, several literatures show the importance of cultural aspects as well as economic and industrial structural factors. Therefore, this study attempted to develop a forecasting model by considering cultural factors along with economic and industrial structural factors in calculating the import volume of each country from Korea. In particular, this study approaches the influence of cultural factors on imports of Korean products from the perspective of PUSH-PULL framework. The PUSH dimension is a perspective that Korea develops and actively promotes its own brand and can be defined as the degree of interest in each country for Korean brands represented by K-POP, K-FOOD, and K-CULTURE. In addition, the PULL dimension is a perspective centered on the cultural and psychological characteristics of the people of each country. This can be defined as how much they are inclined to accept Korean Flow as each country's cultural code represented by the country's governance system, masculinity, risk avoidance, and short-term/long-term orientation. The unique feature of this study is that the proposed final prediction model can be selected based on Design Principles. The design principles we presented are as follows. 1) A model was developed to reflect interest in Korea and cultural characteristics through newly added data sources. 2) It was designed in a practical and convenient way so that the forecast value can be immediately recalled by inputting changes in economic factors, item code and country code. 3) In order to derive theoretically meaningful results, an algorithm was selected that can interpret the relationship between the input and the target variable. This study can suggest meaningful implications from the technical, economic and policy aspects, and is expected to make a meaningful contribution to the export support strategies of small and medium-sized enterprises by using the import forecasting model.

• Journal of Environmental Health Sciences
• /
• v.42 no.6
• /
• pp.396-408
• /
• 2016

Objectives: The purposes of this study were to determine the relationship between the prevalence of allergic diseases and urinary cadmium concentration among children from six to 12 years of age, and to evaluate the association between cadmium in urine and other immunologically related factors in two elementary schools with different environmental conditions. Methods: Data on physician-diagnosed prevalence over the past 12 months and potential risk factors for allergic disease were collected from survey results drawn from 236 children living in different regions (central urban vs. suburban) from April to July in 2014 by an ISAAC questionnaire. We analyzed cytokine levels in serum through enzyme-linked immunosorbent assay and urinary cadmium concentration by use of inductively coupled plasma mass spectrometry. Results: Concentrations of urinary cadmium in suburban and central urban children were $0.11{\pm}0.11ug/L$, $0.14{\pm}0.17ug/L$, respectively (p>0.05). Results from the analysis of the t-test and chi-square test showed that urinary cadmium levels were positively associated with environmental factors (paternal smoking status, passive smoking, traffic volume and experiences of outdoor odors) and individual genetic factors (parental allergic disease). Cadmium concentrations in urine were also positively associated with the prevalence of allergic disease and immune-related cytokines (eosinophils, IgE, IL-5, IL-33, IL-17). Conclusion: This study suggests that genetic factors (parental history of allergic diseases), environmental factors, and regional status (suburban and central urban) should be considered as probable factors increasing the concentration of urinary cadmium, which has the potential to influence the allergic disease prevalence of school-age children.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.3
• /
• pp.677-683
• /
• 2016

In urban areas, underground tunnel construction sites have spread widely to accommodate rapidly increasing traffic volume along with a high-degree economic growth. Earth tunneling might be adapted frequently for the underground space securing, and various tunneling methods have been developed to stabilize the tunnel face and crown. Among them, the DSM (divided shield method) is gaining popularity for its enhanced stability and construction efficiency. This method has its foundation from the Messer Shield method, which is one of the trenchless special tunneling methods. This study examined the effects of face reinforcement on construction the sequence through a large scale soil chamber test and numerical analyses. The chamber has a size of a 1/2 scale of the real tunnel. Surface settlements were measured according the tunneling process. Commercially available software, MIDAS GTS, was used for numerical analysis and its result was compared with the values obtained from the chamber test. The results of the study show that both settlements of the embanked soils and the stress of the tunnel girder are located within the safe criteria. Overall, this study provides basic data and the potential of using a reinforced tunnel face to enhance DSM applications.

• Journal of Trauma and Injury
• /
• v.20 no.2
• /
• pp.77-82
• /
• 2007

Purposes: There have been many efforts to improve the service of emergency centers. In spite of these, no evidence is showing any landmark advancement of emergency services, especially in the hospital stage, exists. We need some efficient standard criteria to evaluate emergency service in the hospital stage, and a useful method might utilize the overcrowding index. We want to know the change in the overcrowding index at a regional emergency center after injury area administration. Injury area means an area in which only an assigned duty physician manages patients with injuries such as those from traffic accidents, falls, assualts, collisions, lacerations, amputations, bums, intoxication, asphyxia, drowning, animal bites, sexual assualts, etc. Methods: We started to operate an injury area in our emergency department from late 2004, and from January to June in 2004 and in 2005, we collected patients' data, age, sex, assigned department, and result from hospital order communication system to figure out overcrowding indices and result indices. We found the daily number of patients, the turnover rate, the admission rate, the ICU admission rate, the emergency operation rate, the ED stay duration, and the ED patient volume to be overcrowding indices. Also we found the withdrawal rate, the transfer rate, and mortality to be result indices. We compared these indices between 2004 to 2005 by using a t-test. Results: There was a significant increase in the daily number of visiting patients in 2005, overcrowding indices, such as the turnover rate, the admission rate, the ICU admission rate, and the emergency operation rate, also showed statistically significant increases in 2005 (P<0.001). As for the result indices, there was a noticeable decrease in the number of withdrawals (11.77/day in 2004 to 4.53/day in 2005). Conclusion: Operating an injury area in a mildly overcrowded local emergency center is beneficial. Evaluating the effect of operating an injury area and it's impact on hospital finances by conducting a similar study analyziing patients for a longer duration would be valuable.

• Journal of the Korean Institute of Gas
• /
• v.24 no.2
• /
• pp.22-28
• /
• 2020

In this study, quantitative risk assessment was carried out for city gas high-pressure pipelines crossing through urban rivers. The risk assessment was performed based on actual city gas properties, traffic volume and population and weather data in the worst case scenario conditions. The results confirmed that the social and individual risks were located in conditionally acceptable areas. This can be judged to be safer considering that the risk mitigation effect of protecting the pipes or installing them in the protective structure at the time of the construction of the river buried pipe is not reflected in the result of the risk assessment. Also, SAFETI v8.22 was used to analyze the effects of wind speed and pasquil stability on the accident damage and dispersion distances caused by radiation. As a result of the risk assessment, the safety of the pipelines has been secured to date, but suggests ways to improve safety by preventing unexpected accidents including river bed changes through periodic inspections and monitoring.