• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.620-623
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• 2014

Network topology for communication between vehicles are quickly changing because vehicles have a special movement pattern, especially character which is quickly changed by velocity and situation of road. Because of these feature, it is not easy to apply reliable routing on VANET(Vehicular Ad-hoc Network). Clustering method is one of the alternatives which are suggested for overcoming weakness of routing algorithm. Clustering is the way to communicate and manage vehicles by binding them around cluster head. Therefore choosing certain cluster head among vehicles has a decisive effect on decreasing overhead in relevant clustering and determining stability and efficiency of the network. This paper introduces new cluster head selection algorithm using RSU(Road Side Unit) different from existing algorithms. We suggest a more stable and efficient algorithm which decides a priority of cluster head by calculating vehicles' velocity and distance through RSU than existing algorithms.

• Journal of the Korea Society of Computer and Information
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• v.23 no.12
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• pp.73-80
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• 2018

Certification revocation list(CRL) is needed for excluding compromised, faulty, illegitimate vehicle nodes and preventing the use of compromised cryptographic materials in vehicular communications. It should be distributed to vehicles resource-efficiently and CRL computational load of vehicles should not impact on life-critical applications with delay sensitive nature such as the pre-crash sensing that affords under 50msec latency. However, in the existing scheme, when a vehicle receives CRL, the vehicle calculates linkage values from linkage seeds, which results in heavy computational load. This paper proposes, a new CRL distribution scheme is proposed, which minimizes the time for CRL processing of vehicles. In the proposed scheme, the linkage value calculation procedure is performed by road-side unit(RSU) instead of the vehicle, and then the extracted linkage values are relayed to the vehicle transparently. The simulation results show that the proposed scheme reduces the CRL computational load dramatically, which would minimize impact on life-critical applications' operations with low latency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.624-627
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• 2014

In vehicular network, the basic goal is to provide vehicle safety service and commercial service such as ITS(Intelligent Transportation System) or video, etc on the road. And most research concentrated on transportation of safety message in congestion situation. It is important to allocate channel for safety message in congestion situation, but providing suitable service is also important problem in vehicular network. For this reason, IEEE 1609.4 allocate 4 multiple service channels (SCHs) for non-safety data transfer. But, in congestion situation with many vehicles, the contention for channel acquisition between services becomes more severe. So services are provided improperly because of lack of service channel. This paper suggests dynamic channel allocation algorithm. The proposed algorithm is that RSU(RaodSide Unit) maintain and manage the information about service and status of channels. On based of the SJF(Shortest Job First) scheduling using those information, RSU selects the most appropriate channel among the 4 SCHs allocated by IEEE 1609.4 in network congestion situation.

• Journal of the Korea Society for Simulation
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• v.19 no.2
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• pp.137-145
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• 2010

This study presents an RTS(Real-time Traffic System) based on an LBS(Location Based Service) using 5.8~5.9GHz RSU(Road Side Unit). The proposed LBI(Location based Broadcast system on ITS) is a local information-based service supported by RSU for drivers, which has a feature of convergence between T-DMB system and ITS-based RTS. The convergence of local broadcasting station and ITS is realized by two-way communication and supports LBS(Location Based Service) by identifying of vehicle's location using RSU. Real-time information delivery and various services could be provided by information exchanges between LMM and local broadcasting stations. Furthermore, conventional technical limitations have been solved mutually such as transmission area limitation in RTS and one-way communication problem in T-DMB. This support real-time two-way communication to each driver. Therefore, it can be expected that traffic dispersion effects and services expansion for drivers by RTS and LBI. Finally, it is proposed to built and implement test-bed around institute.

• Journal of Korea Multimedia Society
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• v.16 no.2
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• pp.180-189
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• 2013

The SMART Highway project combines road construction with advanced technology and vehicle telecommunications. Its expected outcome is a world-leading intelligent road that is green, fast, and comfortable. A vehicular ad-hoc network(VANET) is the core technology of the SMART Highway, whose transport operation is based on road vehicles. The VANET is a next-generation networking technology that enables wireless communication between vehicles or between vehicles and a road side unit(RSU). In the VANET system, a vehicle accident is likely to cause a serious disaster. Therefore, some information on safety is essential to serve as the key exchange protocol for communication between vehicles. However, the key exchange scheme of the general network proposed for a fast-moving communication environment is unsuitable for vehicles. In this paper, communication between multiple vehicles more efficient and secure key exchange at the vehicle certification by signcryption is proposed.

• The Journal of Korean Institute of Information Technology
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• v.16 no.11
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• pp.69-76
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• 2018

As for V2I(Vehicle-to-Infrastructure) systems with energy-constrained RSUs(Road Side Units), the previous data delivery strategies have not considered the aspect of energy usage at RSUs. A new data delivery strategy has been proposed to determine the RSU's participation in data delivery based on the probability dependent on the RSU's remaining energy, and it showed the lower data delivery time than the previous approaches. In this paper, we propose methods to analyze the number of RSUs participating in data delivery and the variations of RSUs' energy value for the consecutive data deliveries. As a numerical result, compared with the previous strategy, the probability-based data delivery strategy shows the lower number of participating RSUs and the increased average energy value of all RSUs. In addition, from the analytical results, we propose considerations for the real implementations of the similar systems.

• Convergence Security Journal
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• v.13 no.4
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• pp.47-52
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• 2013

VANET(Vehicular Ad-hoc Network) is a kind of ad hoc networks which is consist of intelligence vehicular ad nodes, and has become a hot emerging research project in many fields. It provides traffic safety, cooperative driving and etc. but has also some security problems that can be occurred in general ad hoc networks. In VANET, it has been studies that group signature method for user privacy. However, among a group of group key generation phase and group key update phase, RSU(Road-Side Unit) and the computational overhead of the vehicle occur. In this paper, we propose an efficient group key management techniques with CBF(Counting Bloom Filter). Our group key management method is reduced to the computational overhead of RSU and vehicles at the group key generation and renewal stage. In addition, our method is a technique to update group key itself.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.9
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• pp.791-796
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• 2010

Installing noise barriers is the most common method for reducing the highway traffic noise to the road side residential area. After the report about edge potential concept of a noise barrier, various types of noise reducing devices(NRDs) called "noise reducers" have been suggested for getting more shielding effect on the top of highway noise barriers. But, it has been doubtful about effect of the NRDs in field because there was no appropriate and unified method to estimate the acoustic performance by using field measurement of the NRDs in Korea. In this study, the authors have considered to setup a practical method to test and estimate the acoustic performance of NRDs. For eliminating the noise reduction effect of the NRDs height itself, the source and measuring points are adjusted as highly as the NRDs height. For the frequency weighting in the estimation of the NRDs effect, the highway noise spectra were measured at asphalt and concrete road side and then averaged for a unit spectral parameter.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.361-364
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• 2011

In this paper, This work demonstrates a experimental evaluation for vehicle road noise NVH performance from the component-level NVH measurements of Tire. The power unit noise from tire emitted by cars has been reduced. It has been found that tire noise dominates noise produced by the power train when vehicles are driven at high constant speed. Therefore tire pattern noise is affected by pattern and vehicle and transmission loss. Tire noise mechanism is generated by several mechanisms. The sound of tire can propagate either through the air or through the structure of vehicle. Pattern noise is the result of pressure variations through the air to the interior side of vehicle. Especially, smooth asphalt, the periodicity of tread design, groove depth is important factor, which have an influence on the reduction of tire pattern noise.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.4
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• pp.69-79
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• 2013

A system of tracking a vehicle collects the vehicle location and then transmits the data into a GIS server in order to provide several service areas. An ODU built in the vehicle savesa GPS information data and communicates with the RSU installed in the road over the wave technology. The collected data in RSU is transmitted into the GIS serverand is stored. The system based on the collected GPS data in each vehicle is providing useful and various services between RSU and OBU. In this paper indicates that the system is designed in 2 phasesbased on the collected GPS data. The result comparing to process of GPS data created in 1 phase and 2 phase over the Web GIS service indicates that the capability of process of the GPS data in 2 phase is enhanced in "50.88% ~ 51.81%". Therefore, when the accident is happened the system of tracking the vehicle over GPS tech not only receives the information properly but also provides the emergence rescue services.