• 전기전자학회논문지
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• 제18권3호
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• pp.427-434
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• 2014

차량 통신 환경의 멀티 홉 라우팅은 차량의 이동성, 도로 특성, 차량 분포에 따라 네트워크 토폴로지 및 라우팅 경로의 심한 변동 때문에 지속적으로 유지하기 어렵다. 차량 안전 서비스 유지를 위해 유럽 통신 표준(ETSI: European Telecommunication Standard Institute)을 기반으로 하여 GeoNetworking을 구현하였다. GeoNetworking은 유니캐스트와 브로드캐스트로 데이터를 전달하는 방식이 있다. 본 논문에서는 QualNet 네트워크 시뮬레이터를 이용하여 GeoNetworking에 대한 패킷 전달율과 종단 간 지연 등의 성능 지표를 비교하였다. 이전 연구[5]는 GeoUnicast의 성능만을 평가했다. 본 연구에서는 GeoBroadcast에 대한 연구도 추가적으로 수행하였고, GeoUnicast의 CBF(Contention based Forwarding)와 GeoBroadcast의 Greedy 전달 알고리즘을 비교하여 GeoNetworking에 대한 알고리즘 성능 평가를 진행하였다.

• 한국통신학회논문지
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• 제32권5B호
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• pp.247-256
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• 2007

본 논문에서는 무선 센서 네트워크를 위한 위치 정보의 시간차를 이용한 라우팅 프로토콜(Geo-Back)을 제안한다. Geo-Back은 기존의 위치 기반 라우팅 알고리즘과 달리 주기적인 이웃 노드들의 위치 정보 혹은 하나의 홉 내에 있는 이웃 노드들 수의 정보를 이용하지 않고, 오직 소스와 목적지 노드의 위치 정보만을 이용하며, 최적의 back-off 시간 메커니즘을 사용하여 패킷 전송을 결정한다. 빈번한 토폴로지 변화 환경 하에서, 제안하는 Geo-Back 프로토콜은 업데이트를 위한 브로드캐스트 알고리즘을 사용하지 알고 빠르게 목적지까지 전송하기 위한 최적의 다음 홉을 찾을 수 있으며, 분석 결과 밀집 환경의 무선 센서 네트워크에서 확장성과 향상된 성능을 확인 하였다.

• 한국멀티미디어학회지
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• 제12권4호
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• pp.28-40
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• 2008

Vehicular ad hoc networks (VANETs) are a practical application class of wireless ad hoc networks, which consist of moving vehicles equipped with radio communication capabilities that collaborate to form a temporary network. This paper addresses issues and protocols of multihop routing in such emerging networks in the context of safety and infotainment applications. Due to the highly dynamic mobility of vehicles, frequent link breakage and short connection time are inevitable and, thus, the routing is a challenging task and interest for many researchers and industrial community. The frequent and dynamic change of topology makes the topology-based routing unreliable but the position-based routing more effective. The position-based routing consists of the location service which maps a node id to a geo-graphical position and the forwarding scheme which selects the next hop based on geo-graphical information of the node, its neighbors and the destination. The routing techniques are further categorized into geographical forwarding, trajectory forwarding and opportunistic forwarding based on the forwarding scheme. In this paper, we first present the distinguished properties of VANETs and the challenges and intractable issues posed in designing the routing protocols, followed by the comprehensive survey of existing routing protocols. Then, the different routing protocols designed for VANETs are compared in terms of characteristics, performance and application domains.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.433-435
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• 2007

Geographic wireless sensor networks use position information for Greedy routing. Greedy routing works well in dense network where as in sparse network it may fail and require the use of recovery algorithms. Recovery algorithms help the packet to get out of the communication void. However, these algorithms are generally costlier for resource constrained position based wireless sensor type networks. In the present work, we propose a Void Avoidance Algorithm (VAA); a novel idea based on virtual distance upgrading that allows wireless sensor nodes to remove all stuck nodes by transforming the routing graph and forward packet using greedy routing only without recovery algorithm. In VAA, the stuck node upgrades distance unless it finds next hop node which is closer to the destination than itself. VAA guarantees the packet delivery if there is a topologically valid path exists. NS-2 is used to evaluate the performance and correctness of VAA and compared the performance with GPSR. Simulation results show that our proposed algorithm achieves higher delivery ratio, lower energy consumption and efficient path.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2007년도 춘계학술발표대회
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• pp.1195-1198
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• 2007

In this paper we study the problem of real time support in wireless sensor networks and propose a Real time Geographic Routing Protocol (ReGeo) which routes a packet towards the destination based on a compromise between distance and queue count to reduce traffic concentration wherever it has been determined to be too high and uses Gradient Table to store the route satisfying the delay constraints. We describe our prototype implementation of ReGeo Routing in TOSSIM - a TinyOS mote simulator. The simulation results show that the proposed routing protocol not only increases the packet delivery ratio but also keeps overall End to End Delay under a bounded value.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.637-640
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• 2008

Flood control and river improvement works are carried out every year for the defense of the flood disaster, it is impossible to avoid the damage when there is a flood exceeding the capacity of hydraulic structures. Therefore, nonstructural counter plans such as the establishment of flood hazard maps, the flood warning systems are essential with structural counter plans. In this study, analysis of the internal inundation effect using rainfall runoff model such as PC-SWMM was applied to Woo Ee experimental stream basin. Also, the design frequency analysis for effects of the external inundation was accomplished by main parameter estimation for conclusive hydraulic routing using HEC-RAS model. Finally, inundated areas for flood hazard map were estimated at Woo Ee downstream basin according to flood frequency using HEC-GeoRAS model linked by Arc View GIS.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 춘계학술대회 논문집
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• pp.36-40
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• 2006

The objective of the study is to develop a GIS-based flood map. Hydraulic model (HEC-RAS) is linked with hydrologic model (HEC-HMS) for flood map. Geospatial data processors, HEC-GeoHMS and HEC-GeoRAS, are used for operating HEC-HMS and HEC-RAS. HEC-HMS was calibrated and validated at the Hwa-Ong watershed. HEC-HMS was used for calculating runoff from the Hwa-Ong watershed which consisted of Nam-Yang, Ja-An, U-Eun river sub-watersheds, and HEC-RAS was applied and validated for river flow routing at the Hwa-Ong watershed. The simulated results from HEC-HMS and HEC-RAS were reasonably good compared with the observed data. HEC-RAS and HEC-HMS were applied to simulate flooding from probability rainfall at the Hwa-Ong watershed, and the simulated result was used to develop a flood map. Flood map developed in this study will be used for mitigating and predicting the flood damages.

• Spatial Information Research
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• 제10권2호
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• pp.275-287
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• 2002

HEC-HMS와 HEC-GeoHMS를 이용하여 황룡강유역의 유출분석을 수행하였다. 황룡강유역을 HEC-GeoHMS와 GIS를 이용하여 3개의 소유역으로 분할하고 입력자료를 구축하였다. HEC-HMS의 SCS 유출곡선지수 손실계산모형, Snyder 단위유량도 직접유출모형, 지수함수 감수 기저유출모형, Muskingum 추적모형을 사용하여 선택된 홍수사상에 대한 유출량을 모의하였고 매개변수의 최적화를 실시하였다. 최적화된 매개변수를 사용하여 계산한 첨두유량을 관측치와 비교한 결과 매우 양호한 결과를 얻을 수 있었다. 최적화된 매개변수값은 향후 황룡강유역의 유출량을 계산할 때 사용될 수 있을 것이다.

• International Journal of Computer Science & Network Security
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• 제22권2호
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• pp.167-174
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• 2022

Vehicular Ad hoc Networks are considered as special kind of Mobile Ad Hoc Networks. VANETs are a new emerging recently developed, advanced technology that allows a wide set of applications related to providing more safety on roads, more convenience for passengers, self-driven vehicles, and intelligent transportation systems (ITS). Delay Tolerant Networks (DTN) are networks that allow communication in the event of connection problems, such as delays, intermittent connections, high error rates, and so on. Moreover, these are used in areas that may not have end-to-end connectivity. The expansion from DTN to VANET resulted in Vehicle Delay Tolerant Networks (VDTN). In this approach, a vehicle stores and carries a message in its buffer, and when the opportunity arises, it forwards the message to another node. Carry-store-forward mechanisms, packets in VDTNs can be delivered to the destination without clear connection between the transmitter and the receiver. The primary goals of routing protocols in VDTNs is to maximize the probability of delivery ratio to the destination node, while minimizing the total end-to-end delay. DTNs are used in a variety of operating environments, including those that are subject to failures and interruptions, and those with high delay, such as vehicle ad hoc networks (VANETs). This paper discusses DTN routing protocols belonging to unicast delay tolerant position based. The comparison was implemented using the NS2 simulator. Simulation of the three DTN routing protocols GeOpps, GeoSpray, and MaxProp is recorded, and the results are presented.

• 한국지반환경공학회 논문집
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• 제14권11호
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• pp.55-63
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• 2013

농업용 저수지의 경우, 인위적인 홍수조절 기능이 없어 홍수 발생 시 급격한 저수지 수위상승에 따른 월류로 인해 제체의 파괴위험이 높고, 예 경보 없이 상류에서 유입되는 홍수량을 그대로 방류하여 하류 지역에 농경지 침수 등 홍수피해가 발생할 위험성이 높다. 본 연구에서는 경상북도 상주시에 위치한 지평저수지를 대상으로 수문분석을 실시하여 설계홍수량(200년 빈도의 1.2배)을 산정하고, 저수지 추적기법을 통해 기존 여수로와 사이펀 여수로 설치에 따른 저수지 홍수조절능력을 비교 분석하여 사이펀 여수로의 홍수조절 효과를 분석하였다. 그 결과, 지평저수지의 설계홍수량은 $284.3m^3/s$, 로 산정되었으며, 사이펀 여수로의 사전방류를 통해 수위가 약 40cm 정도 하강하고 방류량은 $91m^3/s$, 정도 감소하는 것으로 분석되었다.