• The Journal of the Korea Contents Association
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• v.3 no.3
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• pp.63-73
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• 2003

Today, in exponential growth of internet, the importance of file caching which could reduce the sun load, the volume of network traffic, and the latency of response has emerged. Actually, in one network, the traffic has reduced by using the cache and this means that file caching can improve the internet environment by cost a fraction of link upgrades. In this paper, we address a dynamic cache group configuration policy, to solve the scalable problem. The simulation result shows that the cache group using our proposal policy reduces the latency of response time and it means that out cache group configuration is more scalable than the static cache configuration.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.1
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• pp.157-165
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• 2017

Intelligent transportation systems are currently being developed for elemental technology development of cooperative intelligent transport systems, which enable vehicles to communicate with each other or reduce the risk of traffic accidents, We have been defining and standardizing services according to the purpose of solving traffic safety problems depending on countries. Therefore, in this study, the developed countries of V2X(vehicle-to-everything) based on USA, Europe, Japan, etc., analyzed the service cases selected in the field demonstration stage after completion of the element technology devanalyzed the service cases selected in the field demonstration stage after completion of the element technology development, and to suggest the direction of futureelopment, and to suggest the direction of future policy direction.

• ETRI Journal
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• v.32 no.3
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• pp.430-439
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• 2010

Inundation of roads by heavy rainfall has attracted more attention than traffic accidents, traffic congestion, and construction because it simultaneously causes travel delays and threatens driver safety. For these reasons, in this paper, we propose an inundation hazard index (IHI) of road links, which shows the possibility of inundation of road links caused by rainfall. To generate the index, we have used two key data sources, namely the digital elevation model (DEM) and past rainfall records of when inundation has occurred. IHI is derived by statistically analyzing the relationships between the normalized relative height of the road links calculated from DEM within the watershed and past rainfall records. After analyzing the practical applicability of the proposed index with a commercial car navigation system through a set of tests, we confirmed that the proposed IHI could be implemented to choose safer routes, with reduced chances of encountering roads having inundation risks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10C
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• pp.1033-1044
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• 2003

In this paper, we propose security management architecture that manages efficiently security systems that are produced by different companies and programmable middleware that can reduce the load of management traffic. The proposed architecture applies programmable networks technology to policy based network management (PBNM). The proposed architecture manages and cooperates various security systems using security policy. Also, the programmable middleware provides convenience of management and reduces the overhead of a policy server by translating security policy into execution command. In addition, using programmable middleware, an administrator can manage various security systems that are produced by different companies. We showed that the programmable middleware could reduce the load of management traffic by comparing processing time for enforcing and transferring of policies/messages between the proposed architecture and PBNM architecture.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.6
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• pp.89-94
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• 2012

In this paper, we considered the performances of PMIPv6 and DMM in the viewpoints of traffic load change and packet delivery latency time, where a new buffering in the previous MAAR is proposed to reduce packet loss during handover. To show the superiority of the DMM and to validate the operation of the buffering scheme, we accomplished its simulation under the typical handover. Our performance comparison results show that the DMM is better than the performance of traffic load change and packet delivery latency time of PMIPv6. We can see that the proposed buffering scheme is better than the existing one in terms of packet loss.

• Journal of Korea Society of Digital Industry and Information Management
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• v.18 no.3
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• pp.33-41
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• 2022

Recently the use of personal mobility devices is rapidly increasing, and the businesses related to personal mobility devices are quickly growing as well. Although the use of personal mobility devices provides convenience for short distance movements, many problems occur due to the lack of safety devices and the absence of associated road traffic laws. The number of accidents caused by using personal mobility devices continues increasing every year, and the injuries or deaths are seriously happening with those accidents. When using personal mobility devices, there are basic safety precautions such as wearing a helmet, prohibiting boarding with more than two people, prohibiting boarding with more than 100kg, prohibiting using after drinking alcohol, and so on. However, it is exposed to traffic accidents because there is no way to check before using the system. Therefore, to ensure the user's safety in using the electric kickboard among personal mobility devices, this paper proposes a system that can check the user's safety state before using the electric kickboard. It is possible to safely use personal mobility devices and prevent accidents by proposing a system structure of the electric kickboard that can be used after checking for the use of more than two people, overweight, wearing a helmet, and drinking alcohol.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1087-1095
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• 2014

A recent major development in computer technology is the advent of the wearable computer system that is based on human-centric interface technology trends and ubiquitous computing environments. Wearable computer systems can use the wireless universal serial bus (WUSB) that refers to USB technology that is merged with WiMedia PHY/MAC technical specifications. In this paper, we focus on an integrated system of the wireless USB over the IEEE 802.15.6 wireless body area networks (WBAN) for wireless wearable computer systems supporting U-health services. And a communication structure that can differentiate QoS of U-health WBAN and WUSB traffic with different priorities is proposed for WUSB over IEEE 802.15.6 hierarchical protocol. In our proposal and performance evaluation, throughputs of U-health WBAN and WUSB traffic are analyzed under single and multiple QoS classes to evaluate the effectiveness of proposed QoS differentiating structure in WUSB over IEEE 802.15.6.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1261-1266
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• 2014

Smart shipyard, all of the business of shipyard by using a mobile application, and the rapid spread of smart equipment, the overload of infrastructure due to a variety of mobile services is expected. Because macrocell and femtecell to reduce the overloading of existing infrastructure, additional core network devices have a problem, in this paper, the efficiency of resources than the communication over the existing infrastructure smart shipyard network to improve, to apply the D2D communication technology that can reduce the load on the infrastructure. The proposed routing path plan in accordance with the transfer method and the traffic type of network configuration and D2D equipment navigation and data for applying a smart shipyard. Whether to execute the function to overload traffic in the core network can send to the optimized path was confirmed by using the state transition diagram. Smart shipyard, by applying D2D communication allow efficient traffic handling than conventional communication method.

• Journal of Navigation and Port Research
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• v.46 no.6
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• pp.576-584
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• 2022

AIS is widely utilized in vessel traffic services for marine traffic safety. In 2021, Korea deployed the high-speed maritime wireless communication system (LTE-Maritime) on the sea following IMO's proposal for the introduction of e-Navigation. In this paper, vessel trajectory data from AIS and LTE-Maritime were used for vessel trajectory prediction to compare and analyze the two systems. The results show that the trajectory prediction error of LTE-Maritime was smaller than that of AIS due to the granular and uniform data provided by LTE-Maritime. Additionally, it was revealed that time interval is the most important factor influencing the errors in trajectory prediction, with the prediction error of LTE-Maritime growing at a slower rate of 17% than AIS. This research contributes to the literature by quantitatively comparing AIS and LTE-Maritime systems for the first time.

• Journal of Korean Society of Transportation
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• v.34 no.5
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• pp.421-436
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• 2016

Public-Private-Partnerships tend to be committed high project development cost and recover the cost through future revenue during the operation period. In general, long-term concession can bring on more revenue to private investors, but short-term concession less revenue due to the short recovering opportunities. The concession period is usually determined by government in advance or by the private sectors's proposal although it is a very crucial factor for the PPPs. Accurate traffic forecasting should be most important in planing and evaluating the operation period in that the forecasted traffic determines the project revenue with user fees in PPPs. In this regards, governments and the private investors are required to consider the traffic forecast risk when determining concession period. This study proposed a model for the optimal concession period in the PPPs transportation projects. Monte Carlo simulation was performed to find out the optimal concession period while traffic forecast uncertainty is considered as a project risk under the expected return of the private sector. The simulation results showed that the optimal concession periods are 17 years and 21 years at 5.5% and 7% discount level, respectively. This study result can be applied for the private investors and/or any other concerned decision makers for PPPs projects to set up a more resonable concession period.