• Asia pacific journal of information systems
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• v.26 no.3
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• pp.427-448
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• 2016

The stochastic phenomena of traffic network condition, such as traffic speed and density, are affected not only by exogenous traffic control but also by endogenous changes in service time during congestion. In this paper, we propose a mixed M/G/1 queuing model by introducing a condition-varying parameter of traffic congestion to reflect structural changes in the traffic network. We also develop congestion indices to evaluate network efficiency in terms of traffic flow and economic cost in traffic operating system using structure-changing queuing model, and perform scenario analysis according to various traffic network improvement policies. Empirical analysis using Korean highway traffic operating system shows that our suggested model better captures structural changes in the traffic queue. The scenario analysis also shows that occasional reversible lane operation during peak times can be more efficient and feasible than regular lane extension in Korea.

• Korean Institute of Interior Design Journal
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• v.17 no.1
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• pp.138-145
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• 2008

This study is conducted to formulate various spatial compositions for mixed-use elementary schools in order to use them as community centers. Accordingly, this study is conducted to analyze currently operating community-use elementary schools to find out about the current condition of mixed-use facilities, and the types of mixed-use facilities will be derived from the analysis. In addition, a more effective method of planning mixed-use elementary schools is investigated. By incorporating various educational curricula and teaching/learning activities, major points, which should be considered when planning elementary schools, will be suggested to effectively respond to the changes of educational environment in the future. The results show that in terms of inner traffic flow type, 9 schools out of the schools under study showed a unificated traffic flow type or a cross traffic flow type. When traffic overlaps, problems of noise, visual distraction, and decreased learning performance can appear. To prevent the conflict between areas and to manage areas effectively, each area should be differentiated by installing doors and shutters and by marking guides, and the facility used for community residents and students should also be scheduled separately to avoid time conflict. In addition, to accommodate the changes of users, flexible space planning options should be considered.

• International Journal of Internet, Broadcasting and Communication
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• v.8 no.4
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• pp.1-10
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• 2016

This paper considers WiMedia UWB network based wireless ship area network (WSAN) so as to support high-quality multimedia video data services and important shipboard control data. In this paper, prioritized contention access (PCA) and distributed reservation protocol (DRP) based on WiMedia UWB (ECMA-368) MAC protocols are combined and proposed to support mixed high-quality video traffic and shipboard control data traffic applying varying DRP and PCA data periods according to channel condition and link parameter ptimization. It is shown that the proposed dynmaic channel allocation of WiMedia UWB MAC protocol can provide reliable mixed video and shipboard control data traffic as well.

• International Journal of Highway Engineering
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• v.19 no.3
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• pp.65-70
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• 2017

PURPOSES : Pavement Management System contains the data that describe the condition of the road. Under limited budget, the data can be utilized for efficient plans. The objective of this research is to develop a mixed integer program model that maximizes remaining durable years (or Lane-Kilometer-Years) in road maintenance planning. METHODS : An optimization model based on a mixed integer program is developed. The model selects a cluster of sectors that are adjacent to each other according to the road condition. The model also considers constraints required by the Seoul Metropolitan Facilities Management Corporation. They select two lanes at most not to block the traffic and limit the number of sectors for one-time construction to finish the work in given time. We incorporate variable cost constraints. As the model selects more sectors, the unit cost of the construction becomes smaller. The optimal choice of the number of sectors is implemented using piecewise linear constraints. RESULTS : Data (SPI) collected from Pavement Management System managed by Seoul Metropolitan City are fed into the model. Based on the data and the model, the optimal maintenance plans are established. Some of the optimal plans cannot be generated directly in existing heuristic approach or by human intuition. CONCLUSIONS:The mathematical model using actual data generates the optimal maintenance plans.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.23 no.5
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• pp.293-307
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• 2024

In mixed traffic conditions, the conservative driving behavior of autonomous vehicles (AV) would negatively affect overall traffic performance. In order to manage mobility and safety in mixed traffic conditions, it is essential to scientifically evaluate driving behavior using autonomous driving data collected from real-world. This study proposed a methodology to evaluate the driving behavior of autonomous vehicles (AV) and manual vehicles (MV) at different types of intersections using the Waymo Open Dataset. Urban street were identified through video data, and the autonomous driving conservativeness index (ADCI) was devised to compare the difference in time-to-collision (TTC) based conflict rates between AV and MV in car following situations. The results showed that unsignalized 4-way intersections had the highest ADCI value, indicating greater conservativeness in driving behavior. This indicates the necessity of analyzing the driving behavior of each road section and deriving support measures to prevent AV from negatively affecting the overall traffic performance in mixed traffic conditions. The methodology of this study is expected to serve as foundational for analyzing factors affecting AV using real-world datasets.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4D
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• pp.469-476
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• 2008

Recently, TOD gains popularity as a traffic solution measure of high density urban regeneration projects. The purpose of this study is to investigate traffic impacts of high density TOD projects, and to identify the issues to be resolved. For a case study, it chooses Gangnamgucheong station in Gangnam area served by two subway lines, and designates 400m radius from the station as a site for high-density development. The MOEs chosen for this study is traffic volume, time, distance, speed, and mode share. The SECOM model is adopted for traffic simulation. The analysis results show that high-density TOD is an effective tool for traffic improvement even with only one station area being implemented. It is found that the traffic volume increases near the station in nature where high-density development occurs, but it declines overall in the rest of Gangam area. The total travel time and distance of passenger vehicles decline, meaning that the traffic condition becomes better than before. With regulation on parking supply, the improvement becomes more vivid. In terms of the changes of traffic speed, both alternatives show 4.1% increase in speed, but the difference between alternatives is not quite noticeable because of the induced vehicle demand driven to the streets with improved traffic condition. The mode share changes occur for the benefit of subway ridership, because the study station is equipped with two subway line services. When mixed with parking supply restriction, the impact becomes clearer.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.77-82
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• 2012

To share the lanes with conventional vehicles, traffic operation strategy is needed for NEV (Neighborhood Electric Vehicle). Because NEV cannot accelerate sharply as fast as common car include gasoline, diesel and LPG cars, they may interrupt traffic conditions and make traffic delay. After green lights turn on, all vehicles run through the street including NEV, but NEV have a maximum speed which is 50km/h. It can be an obstacle for following vehicles and will make traffic delay of the intersection. In this reason, we need to organize traffic systems like queue jump with priority traffic signal. To analyze the necessity for NEV road operations, we simulate three scenarios in congested and non-congested conditions. First is that we examine the condition which is mixed NEV and cars on the road, the second one is that we set up lane only NEV can accepted in simulation and last one is making queue jump lane and providing priority signal for NEV. In conclusion, we can conclude that making lane only for NEV is effective to improve travel speed when rate of NEVs is over 20%. Also queue jump lane and priority signal cannot make good effect to intersection delay and average speed.

• Journal of Environmental Impact Assessment
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• v.8 no.3
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• pp.35-47
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• 1999

The purpose of this study is to research the environmental amenity factors of a city to devise the strategies to preserve the factors. For this study, the area of Masan city in Korea was chosen, and questionnaires, field studies, and statistical researches were used. Based on the results, the research showed the city surveyed had expanded by 1,069%, and the population of the city had increased by 272% from 1970 to 1995. In the city-life environment, the traffic was not smooth and the streets were not safe. The number of cars increased by 40,797% from 1970 to 1995, but the total length of roads increased only by 333%. The number of traffic accidents increased by 850%. Buildings were not preserved or maintained and did not have any traditional value. Additionally, buildings were not harmonious with environmental surroundings. Land allocation for utilization was not mixed well with tradition. In relation with the surroundings, there were not enough spaces for old people, and parking spaces were limited. In the field of public policy and finance, economic support and fundamental facilities were not enough. The survey of the household environment and the neighborhood environment showed that the room temperature, sunshine, air condition, and space were medial in the household environment. Public social facilities and entertainment culture had the lowest quality in the neighborhood environment. The city-life environment, the neighborhood environment, and the household environment affected the quality of life in order. The above results showed that cities should be planned upon sustainable development with the idea of emphasizing ecological harmony and considering people first, that citizen should be planned upon sustainable life by the harmony between people and the environment. Cities should be places where all people can live together pleasantly and cooperate with each other.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4432-4450
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• 2014

It is widely observed that in practical wireless cooperative communication systems, different links may experience different fading characteristics. In this paper, we investigate into the outage probability and channel capacity of two-way amplify-and-forward (TWAF) relaying systems operating over a mixed asymmetric Rician and Rayleigh fading scenario, with different amplification policies (AP) adopted at the relay, respectively. As TWAF relay network carries concurrent traffics towards two opposite directions, both end-to-end and overall performance metrics were considered. In detail, both uniform exact expressions and simplified asymptotic expressions for the end-to-end outage probability (OP) were presented, based on which the system overall OP was studied under the condition of the two source nodes having non-identical traffic requirements. Furthermore, exact expressions for tight lower bounds as well as high SNR approximations of channel capacity of the considered scenario were presented. For both OP and channel capacity, with different APs, effective power allocation (PA) schemes under different constraints were given to optimize the system performance. Extensive simulations were carried out to verify the analytical results and to demonstrate the impact of channel asymmetry on the system performance.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.2075-2089
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• 2008

Improvement of transport system is necessary to advance the freight traffic meanwhile logistics are getting bigger and faster by worldwide tendency. The link between each transportations occurs bottleneck state and it raises the necessity of non-stop mixed transport system which can reduce the cost of logistics. DMT(Dual Mode Trailer) was designed to use road and railway at the same time for door to door service. It is called DMT for every transport system which can connect between road and railway in Korea. This study would like to examine the present condition of promotion for localization of DMT which is new idea and technology and suggest the new subjects from now.