• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.608-611
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• 2005

The existing wired emergency call such as 119, 112 have its own location information to serving immediate rescue service. For the case of wireless emergency call by mobile phone, the location information should be provided by wireless network. This paper describes the network architecture and protocol for mobile emergency service referring TIAlEWJ-SID-036-A with reviews about technical issues, legacy factors and related researches. The mobile emergency service is divided into mobile emergency rescue service and mobile emergency alert service. The network reference model for mobile emergency rescue service is released in KOREA. In this paper, the interfaces between elements 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. The protocol is described by DID, and the proposed works are on processing for domestic standard of TTA.

• 한국정보과학회논문지:정보통신
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• 제34권5호
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• pp.379-388
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• 2007

최근 컴퓨터 기술과 네트워크 기술의 급속한 발전과 보급으로 유선환경에서뿐만 아니라 무선환경에서도 이동단말기를 이용하여 네트워크에 접속하여 다양한 작업을 수행할 수 있게 되었다. 사용자들이 네트워크를 통해 이용하는 다양한 어플리케이션들 중에 스트리밍 미디어를 이용하는 어플리케이션의 비중이 높아지고 있으며 이는 유선환경뿐만 아니라 무선환경에서도 마찬가지이다. 스트리밍 미디어는 다른 데이타들에 비해 크기가 매우 크고 높은 네트워크 대역폭과 많은 컴퓨팅 자원을 필요로 한다. 스트리밍 미디어 서비스를 낮은 대역폭과 적은 컴퓨팅 자원을 가지는 이동단말기를 통해 이용할 경우 사용자 환경에 맞게 특화된 서비스가 아니라면 안정적인 서비스를 제공받지 못할 것이다. 특히 이동단말기에서는 배터리를 통한 제한된 에너지 환경을 가지고 있으므로 스트리밍 미디어의 재생을 끝까지 보장하기 위해서는 실시간으로 변화되는 에너지에 대하여 적응적으로 스트리밍을 조절하여야 한다. 본 논문에서는 이동단말기를 위하여 스트리밍 미디어 서비스시에 이동단말기의 에너지 상태에 따라 전송되는 프레임의 수를 동적으로 조절하는 DFRC기법을 연구하였다. 제안하는 기법은 적은 컴퓨팅 자원을 사용하면서 동적으로 스트리밍을 조절하므로 사용자들에게 완전한 재생시간을 보장한다.

• 전기학회논문지
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• 제59권9호
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• pp.1692-1698
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• 2010

In this paper we use wireless sensor network and ultrasonic sensors to estimate local position of mobile robots, and to navigate it. Ultra sonic sensor is simple and accurate so it is good to use in local estimation and navigation of mobile robots. But to obtain accurate distance of two sensors they need to face each others as possible as they can. To solve this problem we rotate ultra sonic sensor which is attached to robot in 360 degrees and obtain accurate distance. We can estimate precise position of mobile robot by triangulation using obtained distance information. A mobile robot navigates using embedded encoder and compensates its coordinates by ultrasonic sensors. Results of Experiments show proposed method obtains accurate distance between sensors and coordinates of position of robot. And mobile robots can navigate designated path well.

• Journal of information and communication convergence engineering
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• 제8권4호
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• pp.399-404
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• 2010

We propose a seamless IPTV transport technology of mobile device. This technology uses multiple interfaces of wireless communication on mobile device. This proposal for transportation of mobile IPTV contents is more mobile and adaptable than other wireless technologies that are currently being used. Algorithm of proposed technology is as follow. When the signal strength of the connected wireless network interface of mobile device is getting lower than specified level, another wireless network interface is connected to continue downloading the IPTV contents in advance. Another connection is maintained until the signal strength of the first connected interface is stable or the interface is connected to another base station (or AP) that have good signal strength. For more seamless services, we consider classifying the packets of mobile IPTV and using dynamic content quality select techniques. Dynamic content quality selection is based on notifying transfer rate to the content delivery network (CDN) server. The proposed technology is expected to use efficiently with both mobile IPTV and the transportation of mobile P2P/P4P.

• ETRI Journal
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• 제35권1호
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• pp.27-34
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• 2013

This paper proposes a network-adaptive mechanism for HTTP-based video streaming over wireless/mobile networks. To provide adaptive video streaming over wireless/mobile networks, the proposed mechanism consists of a throughput estimation scheme in the time-variant wireless network environment and a video rate selection algorithm used to increase the streaming quality. The adaptive video streaming system with proposed modules is implemented using an open source multimedia framework and is validated over emulated wireless/mobile networks. The emulator helps to model and emulate network conditions based on data collected from actual experiments. The experiment results show that the proposed mechanism provides higher video quality than the existing system provides and a rate of video streaming almost void of freezing.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.3775-3788
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• 2014

With the increasing number of the wireless and mobile networks, the way that people use the Internet has changed substantively. Wireless multimedia services, such as wireless video streaming, mobile video game, and mobile voice over IP, will become the main applications of the future wireless Internet. To accommodate the growing volume of wireless data traffic and multimedia services, cognitive radio (CR) and Information-Centric Network (ICN) have been proposed to maximize the utilization of wireless spectrum and improve the network performance. Although CR and ICN have high potential significance for the future wireless Internet, few studies have been conducted on collaborative operations of CR and ICN. Due to the lack of infrastructure support in multi-hop ad hoc CR networks, the problem is more challenging for video streaming services. In this paper, we propose a Cross-layer Video Streaming Mechanism (CLISM) for Cognitive Radio Ad Hoc Information Centric Networks (CRAH-ICNs). The CLISM included two distributed schemes which are designed for the forwarding nodes and receiving nodes in CRAH-ICNs. With the cross-layer approach, the CLISM is able to self-adapt the variation of the link conditions without the central network controller. Experimental results demonstrate that the proposed CLISM efficiently adjust video transmission policy under various network conditions.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제16권12호
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• pp.1194-1198
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• 2010

최근에 출시되는 모바일 단말기들은 여러 개의 무선 통신 네트워크 인터페이스를 갖는 멀티모드 형태이다. 따라서, 특정 무선 통신 인터페이스에 종속되지 않고 에너지의 소비를 줄이기 위하여 네트워크의 환경에 따라 좀 더 에너지 효율적인 네트워크 인터페이스를 선택하여 사용할 수 있다. 본 논문에서는 다수의 무선 통신 인터페이스를 갖는 휴대 장치를 위한 에너지 효율적인 네트워크 인터페이스 선택 기법을 제안한다. 제안하는 기법은 데이터 통신을 위해 폴링을 이용하여 좀 더 에너지 효율적인 네트워크 인터페이스를 선택한다. 또한, 제안하는 기법이 에너지 소비 측면에서 더욱 효율적임을 보인다.

• 한국항행학회논문지
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• 제11권2호
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• pp.217-222
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• 2007

현재의 PC 게임은 인터넷을 이용한 온라인 게임이 주를 이루고 있다. 하지만 모바일 분야에서는 네트워크를 활용한 게임이 전무한 실정이다. 이는 무선 인터넷 환경에서 모바일 네트워크의 낮은 속도 및 모바일 기기의 저사양이 가장 큰 문제로 분석되고 있다. 하지만 3.5세대의 HSDPA(High Speed Downlink Packet Access) 방식의 서비스가 상용화 되고 단말기의 성능이 향상되면서 이러한 문제는 해결되어가고 있다. 이에 본 논문에서는 무선 인터넷 환경에서 모바일 네트워크의 활용을 위한 모바일 온라인 실시간 게임을 구현하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.107-107
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• 2000

This paper focuses on a method to connect mobile devices such as mobile robot, ACV and UTC with Profibus network. In this paper, the IEEE 802.11 wireless LAN is used for wireless extension of Frofibus, and four major issues are introduced to implement the wireless extended Profibus; First, the integration method between Profibus and IEEE 802.11 is introduced. Second, the implementation method of gateway is proposed. Three, the virtual polling mode algorithm is developed for satisfaction of real-time characteristics required in industrial network. Finally, we implement a experimental model, and carried out the performance analysis of wireless extended Profibus. This results show that wireless extended Profibus is suitable to industrial network such as automated container terminal.

• 대한임베디드공학회논문지
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• 제7권2호
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• pp.95-101
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• 2012

In order to supply emotion service depending on user's emotional change in a mobile environment, various researches have been carried. This paper discusses a protocol for wireless charging and an embedded platform of the mobile emotional sensing device which supports that. Wireless charging process relieves user's vexatious task to charge the emotional sensing device. To support wireless charging, there are one basestation and several mobile devices. Basestation coordinates and controls the devices over wireless communication, as well as supplies energy. For 1:N communication we defines the network whose superframe is classified into four categories: a network join superframe, a charging request superframe, a charging superframe and an inactive superframe. Physical layer provides how to supply energy to the devices and communicate physically. Mobile device is equipped with energy charged circuits, which correspond with the defined energy supplying method, as well as bidirectional communication circuits. Mobile device monitors and analyzes its own battery status, and is able to send a request packet to basestation. Therefore, it can be charged before its battery is exhausted without user's perception.