• Journal of Information Processing Systems
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• v.10 no.1
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• pp.103-118
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• 2014

Over the last couple of years, traditional VANET (Vehicular Ad Hoc NETwork) evolved into VANET-based clouds. From the VANET standpoint, applications became richer by virtue of the boom in automotive telematics and infotainment technologies. Nevertheless, the research community and industries are concerned about the under-utilization of rich computation, communication, and storage resources in middle and high-end vehicles. This phenomenon became the driving force for the birth of VANET-based clouds. In this paper, we envision a novel application layer of VANET-based clouds based on the cooperation of the moving cars on the road, called CaaS (Cooperation as a Service). CaaS is divided into TIaaS (Traffic Information as a Service), WaaS (Warning as a Service), and IfaaS (Infotainment as a Service). Note, however, that this work focuses only on TIaaS and WaaS. TIaaS provides vehicular nodes, more precisely subscribers, with the fine-grained traffic information constructed by CDM (Cloud Decision Module) as a result of the cooperation of the vehicles on the roads in the form of mobility vectors. On the other hand, WaaS provides subscribers with potential warning messages in case of hazard situations on the road. Communication between the cloud infrastructure and the vehicles is done through GTs (Gateway Terminals), whereas GTs are physically realized through RSUs (Road-Side Units) and vehicles with 4G Internet access. These GTs forward the coarse-grained cooperation from vehicles to cloud and fine-grained traffic information and warnings from cloud to vehicles (subscribers) in a secure, privacy-aware fashion. In our proposed scheme, privacy is conditionally preserved wherein the location and the identity of the cooperators are preserved by leveraging the modified location-based encryption and, in case of any dispute, the node is subject to revocation. To the best of our knowledge, our proposed scheme is the first effort to offshore the extended traffic view construction function and warning messages dissemination function to the cloud.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.539-542
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• 2011

VANET(Vehicular Ad-hoc Network)은 차량 간의 무선통신(Vehicule to Vehicule: V2V) 또는 차량과 RSE(Road Side Equipment)간의 무선통신(Vehicule to Infrastructure: V2I)을 이용하는 기술이다. 사용자들은 VANET을 통하여 실시간 도로 상황, 응급 상황 등을 파악할 수 있으며 도로 혼잡 등을 줄일 수 있다. 본 논문에서는 VANET 기반 서비스 중 응급상황 알림 서비스에서 발생할 수 있는 Broadcast Storm 문제를 해결하는 라우팅 알고리즘들의 작동 원리와 문제점을 분석한다.

• IEMEK Journal of Embedded Systems and Applications
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• v.4 no.1
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• pp.42-49
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• 2009

Most Vehicular Ad hoc Network (VANET) applications rely heavily on broadcast transmission of traffic related information to all reachable nodes within a certain geographical area. Among various broadcast approaches, flooding is the first broadcasting technique. Each node rebroadcasts the received message exactly once, which results in broadcast storm problems. Some mechanisms have been proposed to improve flooding in Mobile Ad hoc Networks (MANET), but they are not effective for VANET and only a few studies have addressed this issue. We propose two distance-based and timer-based broadcast suppression techniques: 15P(15percent) and slotted 15P. In the first (distance based) scheme, node's transmission range is divided into three ranges (80%,15%and5%). Only nodes within 15% range will rebroadcast received packet. Specific packet retransmission range (15%) is introduced to reduce the number of messages reforwarding nodes that will mitigate the broadcaststorm. In the second (timer-based) scheme, waiting time allocation for nodes within 15% range isused to significantly reduce the broadcaststorm. The proposed schemes are distributed and reliedon GPS information and do not requireany other prior knowledge about network topology. To analyze the performance of proposed schemes, statistics such as link load and the number of retransmitted nodes are presented. Our simulation results show that the proposed schemes can significantly reduce link load at high node densities up to 90 percent compared to a simple broadcast flooding technique.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.3
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• pp.563-577
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• 2018

In order to support secure communication in VANET(Vehicular Ad hoc Network), messages exchanged between vehicles or between vehicle and infrastructure must be authenticated. In this paper, we propose a hierarchical anonymous authentication system for VANET. The proposed system model reduces the overhead of PKG, which is a problem of previous system, by generating private keys hierarchically, thereby enhancing practicality. We also propose a two-level hierarchical identity-based signature(TLHIBS) scheme without pairings so that improve efficiency. The proposed scheme protects the privacy of the vehicle by satisfying conditional privacy and supports batch verification so that efficiently verifies multiple signatures. Finally, The security of the proposed scheme is proved in the random oracle model by reducing the discrete logarithm problem(DLP) whereas the security proof of the previous ID-based signatures for VANET was incomplete.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.650-652
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• 2013

As VANET(Vehicular Ad-hoc NETwork) improves road safety, efficiency, and comfort, and provides a value-added service such as commerce information or internet access. it is the most important technology in ITS(Intelligent Transportation System). But, In VANETs, better communication efficiency can be achieved by sacrificing security and vice versa. VANETs cannot get started without either of them. Therefore, to solve these problems simultaneously, this paper proposes MAC(Message Authentication Code) based SDAP(Secure Data Aggregation Protocol) which removes redundant data or abnormal data between vehicles and verifies the integrity of message. The MAC based SDAP not only improves the efficiency of data delivery but also enhances the security by detecting malicious attacks such as propagation jamming attack, forgery attack, and disguised attack.

• Convergence Security Journal
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• v.10 no.1
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• pp.41-48
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• 2010

Greedy protocols show good performance in Vehicular Ad-hoc Networks (VANETs) environment in general. But they make longer routes causing by surroundings or turn out routing failures in some cases when there are many traffic signals which generate empty streets temporary, or there is no merge roads after a road divide into two roads. When a node selects the next node simply using the distance to the destination node, the longer route is made by traditional greedy protocols in some cases and sometimes the route ends up routing failure. Most of traditional greedy protocols just take into account the distance to the destination to select a next node. Each node needs to consider not only the distance to the destination node but also the direction to the destination while routing a packet because of geographical environment. The proposed routing scheme considers both of the distance and the direction for forwarding packets to make a stable route. And the protocol can configure as the surrounding environment. We evaluate the performance of the protocol using two mobility models and network simulations. Most of network performances are improved rather than in compared with traditional greedy protocols.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.1
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• pp.17-31
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• 2010

In VANET (Vehicular Ad hoc NETwork), vehicles can efficiently verify a large number of signatures efficiently using batch verification techniques. However, batch verification performed independently in each vehicle raises many redundant verification cost. Although, an RSU (Road Side Unit) can perform the batch verification as a proxy to reduce this cost, it additionally requires an efficient method to identify invalid signatures when the batch verification fails. In this paper, we analyze several ways of constructing a distributed batch verification system, and propose an efficient distributed batch verification system in which participating vehicles perform batch verification in a distributive manner for a small size signature set. In our proposed system, each node can report the batch verification result or the identified invalid signatures list and the RSU who received these reports can identify the invalid signatures and efficiently exclude them.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.106-107
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• 2016

Vehicular Adhoc Network는 accident warning, road condition message와 같은 도로상의 정보를 vehicle-to-vehicle 통신을 통해 주어진 목적지까지 얼마나 빠르고 정확하게 전송하는 것이 주요 이슈이다. 무선 센서 네트워크의 많은 타입들 중에서 VANET 환경에 적합한 source 기반의 라우팅 프로토콜은 불안정한 이동 네트워크의 역할을 충실히 수행할 수 있다. Source 라우팅 기법들을 연구하는데 road topology와 map 정보가 사용되며, 본문에서는 도로의 상황과, 라우팅이 직접 수행되는 영역을 부분으로 나누어 각 영역에 속한 이동 노드를 파악하여 다중 경로 라우팅 방안을 제시하여 error 발생과 link fail에 대한 신속한 대처를 수행한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.142-145
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• 2014

지금까지 교통사고 예방을 위한 도로 정보 등을 제공하기 위해 차량 간 통신 네트워크인 Vehicular Ad hoc NETwork (VANET)연구가 활발히 진행되어왔다. 그러나 각 자동차의 On board unit (OBU)의 계산 능력, 저장 공간 등을 효율적으로 사용하는 연구는 진행되어 오지 않았다. 2011년 Olariu et al. 가 cloud computing을 기존의 VANET에 적용하는 개념인 Autonomous Vehicular cloud[1]를 제시하면서 새로운 VANET 연구의 새로운 장을 열었다. 기존의 VANET연구는 지금까지의 각각의 자동차의 통신 성능을 높이는 것에 초점을 맞추었지만, 새로운 아이디어는 높아진 각 자동차의 능력을 효율적으로 이용하여, 유용하게 사용하는 것에 초점을 맞추었다. 이것은 Intelligent Transport System (ITS)의 구축에 한발 더 나아갈 수 있게 하였다. 그 이후 VANET cloud computing (VCC)에 관한 많은 연구들이 진행되었으나 보안적인 측면에서는 아직 연구가 미흡한 실정이다. 그래서 본 논문에서는 보안을 보완한 VCC 아키텍처를 제안한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.794-797
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• 2015

As the interest in VANET is increased, a study on the beacon message transmission between vehicles is actively being made. IEEE 802.11p/1609.4 standard is based on a multichannel system consisting of multiple service channels (SCH) and a control channel (CCH). Multiple SCHs are defined for nonsafety data transfer, while the CCH is used to broadcast safety messages called beacons and control messages (i.e., service advertisement messages). However, most messages broadcast in the only one CCH belong to safety application that must be contested in dense vehicular network. This paper suggests safety message transfer algorithm in dense vehicular congestion. The proposed algorithm is that the priority of safety messages is decided by decision tree and messages are stored in proper queues according to their priorities. Then, safety messages with higher priorities are sent in turn by CCH in the assigned time. The proposed algorithm decreases the beacon transmission delay and increase on the probability of a successful beacon reception in an IEEE 802.11p/1609.4-based network.