• Journal of Korea Multimedia Society
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• v.15 no.3
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• pp.372-379
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• 2012

This paper presents a group based propagation method for multi-hop transmission, in order to deliver an emergency message to the reasonable size of vehicle troop. A group head is selected in considering of the position information of vehicles and radio transmission range. With benefits of the group based transmission, it is possible to minimize the unnecessary transmissions and the possibility of message collisions. We evaluate the performance of the proposed scheme compared with conventional schemes. Simulation results show that the message propagation performance is so stable regardless of vehicle's congestion degree.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12A
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• pp.1113-1121
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• 2010

The Vehicle Safety Communications (VSC) is one of VANET applications for preventing vehicle accidents, and it utilizes vehicle-to-vehicle communication to exchange emergency messages. To propagate such messages in VSC, several schemes based on selective flooding have been proposed. Their common idea is that an emergency message is relayed by one of vehicles receiving the message. However, the schemes do not consider the transmission errors and duplications of an emergency event. In the schemes, if there are transmission errors and a vehicle detects a hazard, there may be vehicles which fail to receive an emergency message. If k vehicles detect a hazard, k emergency messages are created and propagated. The duplications of an event increase reliability of the message delivery but decrease efficiency. In this paper, we propose an emergency message delivery scheme which is efficient and robust to transmission errors. Our proposed scheme utilizes clustering for massage aggregation and retransmissions in a cluster. It also uses an acknowledgment mechanism for reliable inter-cluster communication. Our simulation results show that the proposed scheme outperforms Least Common Neighbor Flooding which is one of the selective flooding schemes.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.451-453
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• 2011

VANET 환경에서 차량의 안전을 위한 긴급 메시지 전달 기법의 연구가 활발히 이뤄지고 있다. 차량이 긴급 상황에 대처하기 위해서는 긴급메시지가 신속하게 주변 전파되어야 한다. 많은 노드들에게 빠른 시간에 전파하기 위해 이용되는 Flooding 방식은 빈번한 브로드캐스트로 인하여 네트워크 전체의 트래픽이 증가하게 된다. 이로 인하여 데이터의 전송 지연상황이 발생한다. 이러한 문제점을 막기 위해 Selective Flooding 방식이 도입되었으나 메시지의 중복으로 인한 Flooding은 고려되지 않았다. 따라서 본 논문에서는 클러스터링을 활용하여 기존의 Selective Flooding 방식에서의 overhead를 줄여 빠른 메시지 전달을 할 수 있는 방법을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.280-283
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• 2013

최근 원자력 발전소, 의료 시스템, 항공 시스템 등과 같이 사람의 생명과 밀접하게 관련되어 있는 소프트웨어로 제어하는 시스템들이 점차 늘어나고 있다. 차량에서 또한 차량 제어 소프트웨어의 오작동으로 인한 잦은 사고로 인하여 운전자와 탑승자의 생명을 위협 받고 있다. 이러한 문제로 인하여 차량시스템 제어 소프트웨어도 안전성 확보를 위한 기술로 차량에 통신 기술을 접목한 차량 통신 기술에 대한 관심이 높아지고 있다. 차량 운전자 뿐 아니라 탑승자의 안전과 밀접하기 때문에 많은 연구가 진행되고 있다. 이러한 많은 연구 중 긴급메시지전송 시스템은 차량 간 통신(V2V)을 통한 운전자의 안전성 확보에 대한 연구다. 본 논문에서는 차량 긴급메시지 전송에 필요한 모듈을 구조적으로 나누고 이를 통하여 긴급메시지 전송시스템 구조의 안전성을 평가한다. 긴급메시지 전송시스템의 안정성을 검증하기 위하여 오토마타 모델링을 통한 시스템 구조를 설계하고 검증을 위해 CTL 논리식 정의, SMV(Symbolic Model Verifier)검증도구를 통한 시스템 안전성 모델 검사를 하였다.

• Journal of KIISE:Information Networking
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• v.34 no.5
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• pp.340-347
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• 2007

Vehicle safety service can be effectively achieved with inter-vehicle communication technologies, in which moving vehicles transmit a safety related urgency information such as traffic accidents, sudden stops, obstacle appearance etc. They usually utilize a broadcast of message propagation method because the communicating vehicles are not known each other. The pure broadcasting scheme does not satisfy the requirements of vehicle safety communication service due to the transmission delay with frequent message collisions. To resolve this problem, this paper presents a group based propagation method for the multi-hop transmission, in order to deliver an urgency message to the reasonable size of vehicle troop. A group header is elected in considering of the position information of vehicles and radio transmission range. And a vehicle equivalent group is formed with the header. With benefits of the group based transmission, it is possible to minimize the unnecessary transmission and the possibility of message collisions. Simulation results show that the message propagation performance is so stable regardless of vehicle's congestion degree.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.560-563
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• 2012

VANET(Vehicular Ad hoc Network)시스템은 차량 간의 무선 통신을 통해 구성되는 임시적인 네트워크이다. 이 네트워크를 통행 차량사고 알림과 같은 긴급메시지를 보내게 되면, 운전자는 이를 알아차리고 대응 할 수 있게 된다. 이런 긴급메시지는 전파를 하는데 있어서 짧은 지연시간과 높은 신뢰성이 보장되어야 한다. 그리고 또 하나의 요소가 필요한데 그것은 방향성이다. 긴급메시지를 사고가 발생한 후방차량으로 알릴 수 있어야 하며, 이런 유용한 정보를 운전자 받아 들여 사고를 미연에 방지 할 수가 있다. 본 논문에서는 이러한 방향성을 고려하게 된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3B
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• pp.224-231
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• 2006

The location information of wired 112, 119 emergency call is provided immediately by subscriber database of KT. But emergency call made by mobile phone should be ask location information to mobile network. This paper proposes the network protocol for mobile emergency service refer to TIA/EIA/J-STD-036-A with reviews about technical issues, legacy factors and related researches. The mobile emergency service is divided to mobile emergency rescue service and mobile emergency alert service. The network reference model for mobile emergency rescue service is released in domestic sector. In this paper, the interfaces between modules of the network reference model, and service scenarios, message flows are defined. Supplement to mobile emergency rescue service, the network reference model, interfaces and message flows for mobile emergency alert service are developed.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1297-1307
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• 2013

Several multi-hop applications developed for vehicular ad hoc networks use broadcast as a means to either discover nearby neighbors or disseminate useful traffic information to othet vehicles located within a certain geographical area. However, the conventional broadcast mechanism may lead to the so-called broadcast storm problem, a scenario in which there is a high level of contention and collision at the link layer due to an excessive number of broadcast packets. To solve broadcast storm problem, we propose an RPB-MACn-based LV-CAST that is a vehicular broadcast algorithm for disseminating safety-related emergency message. The proposed LV-CAST identifies the last node within transmission range by computing the distance extending on 1 hop from the sending node of an emergency message to the next node of receiving node of the emergency message, and the last node only re-broadcasts the emergency message. The performance of LV-CAST is evaluated through simulation and compared with other message dissemination algorithms.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.205-210
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• 2006

차량간 무선통신을 이용한 긴급메시지 전파는 도로 주행 중에 발생할 수 있는 도로의 결빙, 낙석, 공사, 안개, 급커브 등의 위험 상황을 사전에 신속히 위험 지역의 차량들에게 알려 위험 상황 대처 능력을 크게 개선 할 수 있다. 그러나 차량간 통신은 일반적인 무선통신과 달리 노드의 고속 이동성, 노드 밀도, 네트워크 토폴로지의 빈번한 변화와 같은 차량 환경 고유의 특징을 가진다. 본 논문에서는 차량간 긴급메시지를 신속하게 전달하기 위한 시간예약 기반 릴레이 노드 선정 알고리즘을 제안하였다. 실험결과, 제안한 알고리즘이 거리 기반 릴레이 노드 선정 알고리즘에 비해 네트워크 부하와 전달 지연시간에서 25% 성능 향상을 보였으며, 낮은 노드 밀도에서는 더욱 우수한 성능을 보였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2A
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• pp.203-212
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• 2007

An advanced vehicle safety system can be constructed by exchanging danger-related information ,such as urgency stop, traffic accident, obstacle, and car trouble, among the vehicles. However, because network topology changes rapidly and frequently due to the mobility of vehicles, it is impossible to configure the network for information forwarding in this environment. In the most of vehicle safety communication applications, an emergency message is propagated in a form of broadcasting. The simple broadcasting causes a lot of problems in terms of efficiency due to multi-hop area and radio collision problem. This paper proposes a method of selective message forwarding with stem and branch structure for propagating the emergency messages. However, the proposed method raise the efficiency of message transmission with the selective forwarding based on the priority assignment as its location. We analyze and evaluate the performance by comparing the proposed scheme with other schemes that are presented in the paper.