• Title/Summary/Keyword: OBU

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Sol-Gel Template Synthesis and Characterization of PT, PZ and PZT Nanotubes (PT, PZ와 PZT나노튜브의 졸-겔 형판합성과 특성)

  • Jang, Gi Seok;Bernadette A. Hernandez;Ellen R. Fisher;Peter K. Dorhout
    • Journal of the Korean Chemical Society
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    • v.46 no.3
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    • pp.242-251
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    • 2002
  • We report the synthesis and characterization of the perovskite nanotubes made by sol-gel template syn-thesis.Both lead titanate (PbTiO3 : PT), lead zirconate (PbZrO3 : PZ) and lead zirconium titanate (PbZrO3 -PbTiO3 : PZT) solid solution nanotubes were prepared with a chelate sol-gel of titanium isopropoxide (Ti(OPri)4 ), zirconium tet-rabutoxide (Zr(OBu)4 ) and the respective lead acetate (Pb(OAc)2 -3H2O). WhatmanRanodisc membranes, with a 200nm pore size, served as the template. After the removal of the template in the 6M-NaOH, scanning electron microscopy shows that the shapes formed are 200 nm outer diameter tubes with 50mm lengths. Transmission electron microscopy and electron diffraction reveal that the tubes are polycrystalline. The PT nanotubes so far have shown an anomalous transition temperature, 234.4$^{\circ}C$ as measured by DSC with a small particle size, 15.4 nm determined by X-ray analysis with the aid of Scherrer's equation.

A Study on the Traffic Information System Development Using DSRC (DSRC를 이용한 교통정보시스템 개발 연구)

  • Kwon, Han-Joon;Lee, Jae-Jun;Lee, Seung-Hwan;Lee, Jin-Kweon;Kim, Yong-Deak
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.8 no.6
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    • pp.13-22
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    • 2009
  • Recently, DSRC technology is used in the various fields such as parking system, BIS, ETC, etc. This paper suggests a traffic information system using this DSRC technology. The traffic information processing based on point detection using existing vehicle detection equipment is the system in which a collection and a service are operated separately while the traffic information system based on the link detection using DSRC is able to collect and provide the traffic information through the communication between RSE and OBU. The speed of a traffic congestion is high on the process converted from a point passing speed to a link average speed because the vehicle detection equipment makes the link traffic information into the point information. When the condition of traffic is deteriorated, traffic speed of the vehicle detection equipment becomes higher than DSRC. Especially, in this system, deflection by data of the traffic speed of the traffic information system is much decreased, and the unexpected condition detection and traffic condition are provided promptly.

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A Multicast-Based Handover Scheme for the IEEE WAVE Networks (IEEE WAVE 네트워크를 위한 멀티캐스트 기반 핸드오버 기법)

  • Lee, Hyuk-Joon;Yoon, Seok-Young;Lee, Sang-Joon
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.10 no.2
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    • pp.112-121
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    • 2011
  • The IEEE WAVE standard specification does not support handover operation since it is designed to transmit mainly the ITS-related messages that are limited in length. More advanced multimedia applications such as Internet browsing and streaming of video clips produced by CCTVs, however, require handover support such that a sequence of data packets can be received seamlessly while an OBU's association with the RSUs changes. This paper presents a new handover scheme that can operate without performance degradation in the cases where there are multiple RSUs in the areas of handover by making use of the IEEE 802.11f IAPP Move-notify messages, based on the fast handover scheme with proactive caching by disassociation messages introduced previously. Experimental results from the simulation shows that the proposed handover scheme outperforms the scheme based solely on multicast.

Wireless Mesh Network based on Routing Algorithm for guaranteing QoS between End-to-End in VANET (차량 통신 네트워크에서 End-to-End간의 QoS 보장을 위한 무선 메쉬 네트워크 기반의 라우팅 알고리즘)

  • Ryu, Min-Woo;Yoon, Jae-Seok;Lee, Sang-Shin;Won, Kwang-Ho;Cho, Kuk-Hyun
    • Proceedings of the KAIS Fall Conference
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    • 2011.05a
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    • pp.428-432
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    • 2011
  • 차량 통신 네트워크(VANET, Vehicle Ad hoc NETwork)는 ITS(Intelligent Transport System)의 발전과 함께 운전자의 안전 및 교통 정보, 긴급 메시지 등과 같은 서비스를 실시간으로 가능하게 할 수 있는 차세대 네트워크 기술이다. 이러한 차량 통신 네트워크는 현재 IEEE P1609에서 정의하고 있으며, WAVE(Wireless Access Vehicular Environment)로 알려져 있다. WAVE는 차량에 설치된 OBU(Onboard Unit)와 주변시설에 설치된 RSU(Road Side Unit)을 통하여 통신하며, 차량 간 통신을 지원하는 V2V(Vehicle to Vehicle)와 차량과 주변시설과의 통신을 지원하는 V2I(Vehicle to Infrastructure)로 나뉘어져 있다. 하지만 WAVE에서 정의하고 있는 네트워크 서비스(IEEE P1609.4)는 OBU와 RSU 간의 네트워크 서비스에 초점을 맞추고 있기 때문에 전체 네트워크의 QoS를 보장하기에는 미흡한 상태이다. 따라서 본 논문에서는 차량 통신 네트워크에서 End-to-End 간의 QoS 보장을 위한 무선 메쉬 네트워크 기반의 라우팅 알고리즘을 제안한다. 제안하는 알고리즘은 무선 메쉬 네트워크 노드의 호스트 라우터 기능을 통하여 차량 노드와 이기종 간의 네트워크 서비스를 가능하게 하며, 무선 메쉬 네트워크의 다중 채널을 이용하여 데이터의 중요도에 따른 차등 서비스를 지원한다. ns-2를 이용한 시뮬레이션 결과 제안하는 알고리즘이 QoS를 보장함으로써 차량 통신 네트워크의 성능을 향상시킬 수 있음을 입증하였다.

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Connectivity Management of a Pedestrian Smartphone App in the Cyber-Physical Intersection Systems (CPIS) (사이버-물리 교차로 시스템에서 보행자를 위한 스마트폰 앱의 연결성 관리)

  • Jeong, Han-You;Suramardhana, Tommy Adhyasa;Nguyen, Hoa-Hung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39B no.9
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    • pp.578-589
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    • 2014
  • In this paper, we introduce the concept of cyber-physical intersection systems (CPIS) which interconnects roadside units (RSU) located at the intersection, on-board units (OBU) of moving vehicles, and the smartphone apps, named the Smartphone Agent (SA). At the pedestrian mode of the SA, the connectivity management schemes, such as a location update and a handover control algorithm, are proposed to better support the CPIS services while minimizing the power consumption of the pedestrian's smartphone. We develop a real prototype of the CPIS, including RSU, OBU, and the SA. Based on the numerical results collected from a pedestrian moving around the Pusan National University campus, we validate that the proposed connectivity management schemes can improve not only the power efficiency of the pedestrian's smartphone, but also the quality of the CPIS services.

Design and Implementation of Green Light Optimal Speed Advisory Based on Reference Mobility Models (GLOSA-RMM) in Cyber-Physical Intersection Systems (CPIS) (사이버-물리 교차로 시스템에서 참조이동모형 기반 녹색신호 최적화 가속도 조언의 설계 및 구현)

  • Jeong, Han-You;Suramardhana, Tommy Adhyasa;Nguyen, Hoa-Hung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39B no.8
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    • pp.544-554
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    • 2014
  • In this paper, we introduce a cyber-physical intersection systems (CPIS) which intimately interconnects roadside units (RSU) located at intersection, on-board units (OBU) of moving vehicles, and smartphone apps. Based on the architecture of CPIS, we also present a green light optimal speed advisory based on the reference mobility models (GLOSA-RMM) to reduce intersection stopping time (IST) and fuel consumption. Based on several reference mobility models, the GLOSA-RMM determines the appropriate speed advisory by taking into account the current mobility and the intersection traffic light status, and then provides screen/voice GLOSA instructions to minimize the driver's distraction. We show that the GLOSA-RMM can reduce both the IST and the fuel consumption through the numerical results obtained from the prototype of the CPIS consisting of the OBU, the RSU and the smartphone app.

The Study of Microwave Propagation Model for the Active ETC System (능동방식 ETC 시스템을 위한 마이크로파 전파 모델 연구)

  • 배창호;정희창;김영주;장호성
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 1999.11a
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    • pp.101-105
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    • 1999
  • Electronic Toll Collection(ETC) System makes the telecommunication possible between the Beacon and the On Board Unit(OBU) in vehicle at the highway. In this paper, the propagation path of microwave is modelled and the induced voltage of receiving antenna is analyzed numerically according to multi-path fading effort. In this modelling, we consider the weather condition, polarization and antenna radiation pattern. Also, we suggest the diversity technique in order to re duce the fading effect. In the result, the lading effort is reduced significantly in case of the vertical polarization at the rain condition. The circular polarization is the most desirable in this application. The antenna which has the high directivity, is also desirable. Using the space diversity technique at the Beaten, the fading effect is reduced as the distance increases between the Beacon and OBU. These results are presented at the graphs whose axes are related to the magnitude of received voltage(dB) and the distance of the beacon and a vehicle.

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Blog System for Improving Self-esteem in the Class (사회적 자아 존중감 향상을 위한 학급 블로그 설계 및 구현)

  • Yoo, Seoung-Han;Sung, Young-Hun;Lee, Jae-Inn
    • 한국정보교육학회:학술대회논문집
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    • 2004.08a
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    • pp.614-621
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    • 2004
  • 블로그는 1인 미디어로써 개인의 일상을 자유롭게 청에 기록하는 동시에 트랙백을 통하여 보다 많은 사람들과 연계되어 인간관계를 형성할 수 있는 도구로 각광받고 있다. 본 연구는 이러한 블로그 특성을 이용하여 학급 내 학생들의 사회적 자아 존중감 향상을 위한 학급 블로그 시스템을 설계 구현하였다. 온라인 활동과 오프라인 활동을 별 상점이라는 보상체계로 연계한 학급 블로그 시스템은 학생들의 인터넷 생활을 순화시켜 타인과의 관계를 원만히 하고 컴퓨터 활용 능력을 증대시키는 등 실제 학급에서 유용하게 사용될 수 있을 것이다.

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A Proposal for a Personal Branding Support Service in Social Media Times

  • Kawano, Yoshihiro;Obu, Yuka
    • Journal of Contemporary Eastern Asia
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    • v.12 no.2
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    • pp.49-59
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    • 2013
  • Social media such as Twitter and Facebook have become popular. In the age of social media, many people have become more active online. For example, about half of all global active Internet users are on Facebook (Perry 2012). Personal branding is a very important strategy to build on an individual's strengths, and this kind of branding is expected to contribute to self-actualization. Therefore, the presence of mentors who advise users to discover their own strong points for self-actualization is necessary. In this paper, we propose a personal branding support service, Mentors, which connects mentors and mentees. The core concept is: "Everyone has the face of both a mentor and mentee." The key function is sharing stages of self-analysis in human life design: Determining value, creating a mission, and forming a strategy. From this function, a good match between a mentor and mentee can be found. The program aims to improve human life by understanding the client's strengths and using social media effectively. Future work includes launching Mentors and evaluating its service.

A Robust and Efficient Anonymous Authentication Protocol in VANETs

  • Jung, Chae-Duk;Sur, Chul;Park, Young-Ho;Rhee, Kyung-Hyune
    • Journal of Communications and Networks
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    • v.11 no.6
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    • pp.607-614
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    • 2009
  • Recently, Lu et al. proposed an efficient conditional privacy preservation protocol, named ECPP, based on group signature scheme for generating anonymous certificates from roadside units (RSUs). However, ECPP does not provide unlinkability and traceability when multiple RSUs are compromised. In this paper, we make up for the limitations and propose a robust and efficient anonymous authentication protocol without loss of efficiency as compared with ECPP. Furthermore, in the proposed protocol, RSUs can issue multiple anonymous certificates to an OBU to alleviate system overheads for mutual authentication between OBUs and RSUs. In order to achieve these goals, we consider a universal re-encryption scheme and identity-based key establishment scheme as our building blocks. Several simulations are conducted to verify the efficiency and effectiveness of the proposed protocol by comparing with those of the existing ECPP.