• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2004년도 ICCAS
• /
• pp.350-353
• /
• 2004

The increasing use of Ethernet-TCP/IP network in industry has led to the growing interest in its reliability in real-time applications such as automated manufacturing systems and process control systems. However, stochastic behavior of its medium access scheme makes it inadequate for time-critical applications. In order to guarantee hard real-time communication service in Ethernet-TCP/IP network, we proposed an algorithm running over TCP/IP protocol stack without modification of protocols. In this paper, we consider communication services guaranteeing deadlines of periodic real-time messages over MAC protocols that have unbounded medium access time. We propose a centralized token scheduling scheme for multiple access networks. The token is used to allow a station to transmit its message during the time amount that is appended to the token. The real-time performance of the proposed algorithm has been described.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
• /
• pp.151-154
• /
• 2003

In this paper, we described a method to guarantee a real-time communication in the hetegeneous network for the personal robot. The hetegeneous network is composed of many kinds of network like IEEE1394, Ethernet, CAN, Bluetooth, Wireless Lan and so on. real-time data is transfered via those kinds of network. Those network have different characteristics as speed, bandwidth, Priority. we used IEEE1394, Ethernet, CAN to study in this paper. To guarantee a real-time communication, a worst case response time must be scalable. In this environment to guarantee a real-time communication, we get a worst case response time of each network and a end-to-end worst case response time.

• 한국통신학회논문지
• /
• 제25권10B호
• /
• pp.1675-1689
• /
• 2000

We present CReMeS a CORBA-compliant design and implementation of a new real-time communication service. It provides for efficient predictable and scalable communication between information producers and consumers. The CReMeS architecture is based on MidART's Real-Time Channel-based Reflective Memory (RT-CRM) abstraction. This architecture supports the separation of QoS specification between producer and consumer of data and employs a user-level scheduling scheme for communicating real-time tasks. These help us achieve end-to-end predictability and allows our service to scale. The CReMeS architecture provides a CORBA interface to applications and demands no changes to the ORB layer and the language mapping layer. Thus it can run on non real-time Off-The-Shelf ORBs enables applications on these ORBs to have scalable and end-to-end predictable asynchronous communication facility. In addition an application designer can select whether to use an out-of-band channel or the ORB GIOP/IIOP for data communication. This permits a trade-off between performance predictability and reliability. Experimental results demonstrate that our architecture can achieve better performance and predictability than a real-time implementation of the CORBA Even Service when the out-of-band channel is employed for data communication it delivers better predictability with comparable performance when the ORB GIOP/IIOP is used.

• 한국언론정보학보
• /
• 제46권
• /
• pp.420-448
• /
• 2009

이 연구는 시간의식이 무엇인지를 이론적으로 재정립하고 이것이 TV 커뮤니케이션에서 어떠한 역할을 하는지를 고찰함으로써 인간의 커뮤니케이션 행위에 대한 새로운 관점을 제공하는 것을 목표로 삼고 있다. 과거, 현재, 미래는 독립된 현실이 아니라 인간의 의식속에 공존하고 있으므로 '경험'과 '기대'는 시간의식의 작동방식을 설명하는 데 핵심적인 개념적 도구로 활용되었다. 인간은 현재에 인식되는 경험을 통해 미래를 예측하고 바로 이 예측된 미래, 즉 기대에 따라서 현재의 행동을 결정하거나 감정을 느끼게 된다. 시간의식은 사회화 과정 속에서 상징적 시간도구와 사회의 지배적 세계관을 구성하는 시간관으로 확장된다. TV 커뮤니케이션에서 시간의식의 역할은 TV의 매체적 특수성에 대한 이해를 기초로 하여 뉴스와 드라마 두 장르에서 분석되었다. 뉴스와 드라마에서 공통적으로 경험과 기대의 상호의미작용에 의해 작동하는 시청자들의 시간의식을 어떻게 활용하는가에 따라 재미, 흥미, 새로움 등과 같은 커뮤니케이션 효과의 달성 여부가 달려 있음을 파악할 수 있었다.

• 로봇학회논문지
• /
• 제18권3호
• /
• pp.281-284
• /
• 2023

Real-time control communication network system is important for developing defense robots because it affects environmental interaction, performance, and safety. We propose a real-time control communication network using the Xenomai real-time operating system and the open-source EtherCAT master library, SOEM. EtherCAT is an Ethernet-based industrial communication method. It has low latency and many functions such as cable redundancy and distributed clock synchronization. We use Xenomai RTOS and Intel NUC to develop the system. Experimental tests demonstrate the Real-time EtherCAT master implementation, and communication with CiA301-based slave devices. The jitter measurement was conducted to validate the real-time performance of the system. The proposed system shows possibility for real-time robotics applications in various defense robots.

• 한국멀티미디어학회논문지
• /
• 제17권4호
• /
• pp.433-440
• /
• 2014

Wireless communication offers the flexibility to the node movement at the spatial dimension more than the wire communication not only in IP architecture but also in Content-Centric Networking. Although it gives such advantage, the intra-domain movement of a node especially the data source node affects the communication to the access point node which in the end affects the acceptance ratio of the client node that requests the data packets from the data source node. In this paper, we use time-division access method to maintain the acceptance ratio of the client node as the effect of the intra-domain data source node movement in Content-Centric Networking. The simulation result shows that the acceptance ratio of the client node can be maintained using the time-division access method as long as the interval access time is less than the coherence time.

• 한국군사과학기술학회지
• /
• 제21권5호
• /
• pp.640-648
• /
• 2018

Time division wireless communication in tactical MANET is attractive to deliver both high data rates and long-range coverage, and to provide scheduled QoS to mission participants. This paper is about the time synchronization issue of multi-mission USV in tactical MANET. As USV communication coverage becomes longer, the synchronization error also becomes higher; therefore, which results in link disconnection, and consequent failures of reconnection because base station cannot configure necessary parameters over long-distant terminal. We propose a range adaptive time synchronization method to compensate for synchronization errors. The issue of long-range time synchronization problem was identified during maritime communication tests, and we verified the proposed method through analyses of both indoor and outdoor test results.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제9권3호
• /
• pp.256-265
• /
• 2017

In this paper, an ascheme is proposed for multiuser underwater acoustic communication by using the multi-chirp rate signals. It differs from the well known TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access) or CDMA (Code Division Multiple Access), by assigning each users with different chirp-rate carriers instead of the time, frequency or PN code. Multi-chirp rate signals can be separated from each other by FrFT (Fractional Fourier Transform), which can be regarded as the chirp-based decomposing, and superior to the match filter in the underwater acoustic channel. VTRM (Virtual Time Reverse Mirror) is applied into the system to alleviate the ISI caused by the multipatch and make the equalization more simple. Results of computer simulations and pool experiments prove that the proposed multiuser underwater acoustic communication based on the multi-chirp rate exhibit well performance. Outfield experments carrie out in Xiamen Port show that using about 10 kHz bandwidth, four users could communicate at the same time with 425 bps with low BER and can match the UAC application.

• 디지털산업정보학회논문지
• /
• 제11권1호
• /
• pp.97-109
• /
• 2015

In this paper, we design and implement a two-way automatic communication system using a mobile instant messenger that can provide a customized service through a real-time two-way communication using a mobile instant messaging service. Two-way automatic communication system using a mobile instant messenger can improve the quality and quantity of information in real-time update of the information through the feedback. In addition, since it is communicated by using a mobile Instant Messanger in 1:1 there is no concerns that is recognized as spam, as well as it is possible to provide customized information for each user. Two-way automatic communication system using a mobile instant messanger shows the difference of the speed according to the data input time in typing by hands in result of comparing the time to input a date and the processing speed to search a data. Therefore in category treatment, command processing and natural language processing, Category treatment way is the most excellent in aspect of data processing speed, otherwise in aspect of the total speed to combine the data input time and the processing time, the command processing way is the best method.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2012년도 추계학술대회
• /
• pp.712-714
• /
• 2012

오늘날 웹 브라우저를 이용한 실시간 화상통신기술이 대두되고 있다. 이에 본 논문에서는 웹 브라우저를 활용한 실시간 화상통신 기술에 대해 연구하였다. 이를 기반으로 웹 기반의 실시간 화상통신 시스템을 설계 및 구현하였다. 본 시스템에서는 서로 상이한 웹 브라우저들의 웹서버를 통해 RTC API와 HTTP/WebSockets 등을 사용하여 웹 브라우저에서 실시간 화상통신이 가능하게 하다. 이는 네트워크가 연결된 모든 환경에서 웹 브라우저의 이용이 가능한 모든 단말에서 사용가능하며, 제한적인 환경에서의 화상통신분야에 활용될 것이다.