• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9B
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• pp.1381-1389
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• 2010

The smart grid technology is expected to significantly improve energy efficiency by dynamic power supply. One of its application is the Vehicle-to-Grid(V2G) that utilizes an electric vehicle's battery as a household storage battery. Meanwhile, a lot of researches are recently investigated in the area of wireless energy transfer technology because of its convenience and safety in charging a battery. With the wireless energy transfer infrastructure a wireless magnetic induction communication technique can help the dynamic power supply of the smart grid more efficient. In this paper, we propose a wireless magnetic induction communication sion cowhich includes data transmission and location-aware functions. We expect the sion cohelp the smart grid to control power supply more efficiently. We also developed its test-bed and evaluated the performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.10
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• pp.974-983
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• 2014

The commercialization of ITS(Intelligent Transport System) is in sight including V2V(Vehicle-toVehicle) communication and analysis of related electromagnetic circumstances is essential process in relevant legislation. However analysis including numbers of vehicles have electrically large environment which leads to a lack of computational resources. In this letter, we suggest superposition method which require much less computational resources by subgrouping environment and using post-processing of results. Suggested method approximate original result by superpositioning of analysis which include scatterers near source, observation point. This letter also presented guideline of method and example for comparison with full analysis result.

• The KIPS Transactions:PartC
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• v.17C no.6
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• pp.491-498
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• 2010

Wi-Fi based vehicle-to-infrastructure (V2I) communication is an emerging solution to improve the safety, traffic efficiency, and comfort of passengers. However, due to the high mobility of vehicles and the limited coverage of Wi-Fi APs, the V2I system may suffer from frequent handoffs although roadside APs can support cost effective Internet connectivity. Such problem of V2I systems can be overcome with Mobile AP (MAP) platform. The MAPs yield longer service duration by moving along with vehicles, yet they provide a lower link capacities than the roadside APs. In this paper, we propose a new association control mechanism that effectively determines whether the vehicle will select a fixed roadside-AP or a nearby MAP in mobile vehicular network environments. We consider both the achievable link bandwidth and available connection duration as a selection criterion and provide their run-time estimation method. Extensive simulation using real traces show significant performance improvements.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.9 s.351
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• pp.32-39
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• 2006

5.8GHz DSRC(Dedicated Short Range Communications) is a short to medium range communications service that supports both public safety and private operations in roadside to vehicle and vehicle communication. However the 5.8GHz frequency may cause the shadowing effect or communication blocking problem when there is an obstacle or another vehicle between RSE (Road Side Equipment) and OBE (On Board Equipment). In this paper, to solve this problem of the 5.8GHz DSRC, we propose a relay protocol based on the standard of DSRC radio communication between RSE and OBE in the 5.8GHz band made by TTA (Telecommunication Technology Association). By using the proposed relay protocol to DSRC system and intervehicle communication, we also consider a fixed relay protocol and mobile relay protocol. We expect to apply this relay protocol for the DSRC intervehicle communication and video communication between drivers and safe distance among vehicles in the near future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1691-1699
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• 2014

IEEE developing WAVE specifications are able to support V2V and V2I wireless communications, and these functionalities can be used to enhance vehicle operational safety. To overcome any security weaknesses that are inherent in wireless communications, WAVE specification should support message encryption and authentication functions. In this study, we have implemented WAVE security algorithms in IEEE P1609.2 with openssl library and C language. We have verified the normal operation of implemented software, using the test vectors of related specifications, and measured their performance. Our software is platform independent, and can be used for the full implementation of WAVE specification.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.2
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• pp.480-497
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• 2012

As a new business concept, machine-to-machine (M2M) communications are born from original telemetry technology with the intrinsic features of automatic data transmissions and measurement from remote sources typically by cable or radio. M2M includes a number of technologies that need to be combined in a compatible manner to enable its deployment over a broad market of consumer electronics. In order to provide better understanding for this emerging concept, the correlations among M2M, wireless sensor networks, cyber-physical systems (CPS), and internet of things are first analyzed in this paper. Then, the basic M2M architecture is introduced and the key elements of the architecture are presented. Furthermore, the progress of global M2M standardization is reviewed, and some representative applications (i.e., smart home, smart grid and health care) are given to show that the M2M technologies are gradually utilized to benefit people's life. Finally, a novel M2M system integrating intelligent road with unmanned vehicle is proposed in the form of CPS, and an example of cyber-transportation systems for improving road safety and efficiency are introduced.

• Journal of Korea Multimedia Society
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• v.12 no.6
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• pp.824-832
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• 2009

Multi-radio multi-channel Wireless Mesh Network requires an effective management policy to control the assignment of channels to each radio. We concentrated our investigation on modeling method and solution to find a dynamic channel assignment scheme that is adapted to change of network traffic. Multi-path routing scheme was chosen to overwhelm the unreliability of wireless link. For a particular traffic state, our optimization model found a specific traffic distribution over multi-path and a channel assignment scheme that maximizes the overall network throughput. We developed a simple heuristic method for channel assignment by gradually removing clique load to obtain higher throughput. We also presented numerical examples and discussion of our models in comparison with existing research.

• Information and Communications Magazine
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• v.30 no.11
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• pp.15-23
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• 2013

최근 전 세계적으로 도로교통의 안전성 제고와 효율성 증진, 환경성 및 지속가능성 확보를 목적으로 추진되고 있는 C-ITS의 동향분석을 통해 C-ITS의 아키텍처 및 ITS Station 구성내용을 정리하였다. C-ITS 핵심요소인 ITS Station의 구성방안은 유럽의 DRIVE C2X, 미국의 Connected Vehicle Program의 Model Deployment인 Safety Pilot 프로젝트, 일본의 C-ITS 추진계획, 한국의 SMART Highway 연구개발 사례를 통해 도출하였다. 국내외 C-ITS 연구개발 사례와 국내 도로교통여건 및 현 ITS 환경을 고려한 C-ITS 아키텍처와 ITS Station 구성방안을 4가지 구성요소별로 제시하였고 차량용 ITS Station과 노변 ITS Station의 주요 고려사항과 요구기능으로 현 ITS를 적극적으로 수용하면서 C-ITS 단말의 보급률을 확대하는 방안으로 제안하였다.

• Journal of Korea Multimedia Society
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• v.11 no.12
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• pp.1716-1721
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• 2008

Currently, Wireless Networks have some nice characteristics such as multi-hop, multi-channel, multi-radio, etc but these kinds of resources are not fully used. The most difficulty to solve this issue is to solve mixed integer optimization. This paper proposes a method to solve a class of mixed integer optimization for wireless networks by using AMPL modeling language with CPLEX solver. The result of method is scheduling and congestion control in multi-channel multi-radio wireless networks.

• Journal of the Korea Society for Simulation
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• v.20 no.1
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• pp.19-28
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• 2011

The safety applications based on the IEEE 802.11p, periodically transmit the safety-related information to all surrounding vehicles with high reliability and a strict timeline. However, due to the high vehicle mobility, dynamic network topology and limited network resource, the fixed beacon scheduling scheme excess delay and packet loss due to the channel contention and network congestion. With this motivation, we propose a novel beacon scheduling algorithm referred to as spatial-aware(SA) beacon scheduling based on the spatial context information, dynamically rescheduling the beaconing rate like a TDMA channel access scheme. The proposed SA beacon scheduling algorithm was evaluated using different highway traffic scenarios with both a realistic channel model and 802.11p model in our simulation. The simulation results showed that the performance of our proposed algorithm was better than the fixed scheduling in terms of throughput, channel access delay, and channel load. Also, our proposed algorithm is satisfy the requirements of vehicular safety application.