• The Magazine of the IEIE
• /
• v.31 no.3
• /
• pp.49-56
• /
• 2004

지금까지 end-to-end ethernet 서비스를 실현하기 위한 노력으로 10 Gbps 이상의 ethernet 전송기술, 강력한 보안프로토콜, 그리고 QoS 방안 등이 주가 되어 연구되고 논의되어져 왔다. 본 고에서는 기존의 asynchronous ethernet을 그대로 수용하며 기존 ethernet의 가장 큰 한계점으로 지적되었던 real-time data전송문제를 해결하기 위한 ‘Synchronous Ethernet’ 의 표준화 현황 및 기술을 소개하고자 한다. ‘Synchronous Ethernet’은 현재 공식적으로 정해진 표준이 없는 상태지만 2004년에 국제표준회의에서 새롭고 활발한 활동으로 자리잡을 것으로 보인다.(중략)

• 전기의세계
• /
• v.43 no.12
• /
• pp.67-72
• /
• 1994

ITU-T(구 CCITT)의 X.25에 기초한 패킷교환 방식은 회선교환에 비하여 대역폭을 효과적으로 사용할 수 있는 장점을 갖고 있으나 흐름제어와 오류제어 처리에 따른 지연으로 속도가 64Kbps로 제한된다는 것이 단점이다. 특히 90년대에 들어서부터는 문자 정보만 전송하던 80년대와는 달리 데이타량이 큰 그래픽 및 화상데이타의 전송수요가 늘어나고 있으며 LAN 및 클라이언트 서버 환경의 도입으로 대표되는 기업의 컴퓨팅 환경의 변화가 급속히 이루어지고 있어서 기업의 통신환경이 기존의 패킷교환 방식만을 갖고는 도저히 감당할 수 없게 되었다. 이에 따라 고속 패킷교환기술들이 80년대 후반부터 등장하기 시작하였으며, 공중 데이타망 기술로 대표적인 것은 프레임릴레이(FR), SMDA(Switched Multimegabit Data Service), ATM(Asynchronous Transfer Mode) 등이다.

• Journal of Institute of Control, Robotics and Systems
• /
• v.10 no.2
• /
• pp.197-203
• /
• 2004

A real-time network in a distributed control system plays an important role for the reliable data transmission. Compared to the field-buses used in the past, TCP/IP protocol on the top of Ethered provides a compatibility between applications as well as an economical method to develop softwares. This paper proposes a modified TCP/IP structure for IEEE-1394 network, with which asynchronous and isochronous data transmission is selectively used for the real-time data transmission in a distributed control system. This paper also shows the performance of the proposed protocol by experiments.

• Proceedings of the KIPE Conference
• /
• 2002.07a
• /
• pp.635-638
• /
• 2002

In this paper, the connection device of RS232C and TCP/IP implementation using ARM processor and LINUX is proposed. Data interaction flash memory the multiple serial ports are transferred to ARM processor and the data are processed and formed into data packet for transfer via internet protocol. Packet flash memory Internet is decoded to extract the serial port data. The serial ports supports RS232C asynchronous protocol communication and control program is developed in GNU-C and installed in the on-board memory for packet conversion and control. The research result can be applied to terminal server, printer server and multiple serial ports equipments.

• Educational Technology International
• /
• v.9 no.2
• /
• pp.123-142
• /
• 2008

The purpose of this study was to examine how computer conferencing might facilitate collaborative learning for students to engage in meaningful discussion. The participants in this study consisted of the instructor and the students in a graduate level course. Different sources of evidence were used to triangulate the data: in-depth interviews, content analysis of transcripts of discussion, and other archival data including course syllabus, presentation materials, and lecture notes. Participants perceived web-based learning as collaborative process, providing opportunities to share the idea, respect and evaluate different perspectives, and co-construct new insights. Analysis of the data revealed several challenges related collaboration in a web-based learning environment: absence of a sense of community, technical problems, adaptability to different types of learner, and managing the discussion. The data also indicated that a variety of strategies were used to facilitate learning: building a sense of community, technical support, developing instructional methodologies, class size, and design of the content.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.12
• /
• pp.2366-2373
• /
• 2007

In this paper, a low-power and small-area asynchronous 1 kilobit EEPROM for passive UHF RFID tag chips is designed with $0.18{\mu}m$ EEPROM cells. As small area solutions, command and address buffers are removed since we design asynchronous I/O interface and data output buffer is also removed by using separate I/O. To supply stably high voltages VPP and VPPL used in the cell array from low voltage VDD, Dickson charge pump is designed with schottky diodes instead of a PN junction diodes. On that account, we can decrease the number of stages of the charge pump, which can decrease layout area of charge pump. As a low-power solution, we can reduce write current by using the proposed VPPL power switching circuit which selects each needed voltage at either program or write mode. A test chip of asynchronous 1 kilobit EEPROM is fabricated, and its layout area is $554.8{\times}306.9{\mu}m2$., 11% smaller than its synchronous counterpart.

• Journal of Internet Computing and Services
• /
• v.12 no.1
• /
• pp.27-38
• /
• 2011

In this paper, we propose a multiple access scheme using MHP(Modified Hermite Polynomial) pulse and ternary code for high-data and low-data rate for Out-body WBAN(Wireless Body Area Network). To satisfy the requirement of WBAN system, UWB-IR has been considered as a promising candidate for Out-body WBAN. The proposed multiple access scheme, using orthogonal MHP pulse and ternary code sets, reduces multi-user interference and distinguishes user signal from multi-user signals. We propose two algorithms for synchronous and asynchronous WBAN system. The symbol is constructed by MHP pulses and time hopping duration to reduce multi-user interference in the synchronous WBAN system. The symbol also is constructed by ternary code to avoid collision between pulse trains in the asynchronous WBAN system. The results of the proposed multiple access scheme show a clear improvement of BER.

• Smart Media Journal
• /
• v.9 no.1
• /
• pp.9-15
• /
• 2020

Recently there have been increasing attempts to apply blockchains to businesses and public institutions. Blockchain is a distributed shared ledger with excellent transparency and security of data and through consensus algorithm, the same data can be shared to all nodes in order. In this paper, Modified PBFT which does not modify the PBFT consensus algorithm is proposed. MPBFT is able to tolerate Byzantine faults on a private blockchain on an asynchronous network. Even with the increase of participating nodes, the network communication cost can be effectively maintained. Modified PBFT takes into account the characteristics of an asynchronous network environment where node-to-node trust is guaranteed. In response to the client's request, PBFT performed the entire participation broadcast several times, but Modified PBFT enabled consensus and authentication through the 2 / N leader. By applying the Modified PBFT consensus algorithm, the broadcast process can be simplified to maintain the minimum number of nodes for consensus and to efficiently manage network communication costs.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.3
• /
• pp.40-49
• /
• 1989

A variable-state block interference channel model is presented which matches asynchronous multiple-access slow frequency-hopped spread-spectrum systems which suffer from bursts of interference of variable duration. For variable-state block interference channels test pattern techniques combined with interleaving are presented from which the decoder obtain side information about channel states. By examining test patterns the decoder estimates which parts of data blocks are affected by interference and regards the parts of blocks affected by interference as erasures. Since the presence of test patterns reduces the number of bits for data transmission, test patterns are not useful for variable-state block interference channels for small hit probability, It is shown that test patterns increase the capacities of variable-state block interference channels for large hit probability. It is also shown that test patterns provide a almost full side information about channel states for certain values of parameters.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.8
• /
• pp.1877-1884
• /
• 2014

Because of the limited power resource, we need a reliable low-power media access control technique suitable for unmaned remote sensor operation condition for the unmanned sensor processor to perform the task in the remote wireless network situation. Therefore CSMA/CA and X-MAC is generally considered to effectively transmit the signal in the low-power wireless network. In this paper, we propose the more efficient low-power LP-MAC Technique which consumes the minimum power and transmits the data faster in condition that the mobile nodes' joining to and leaving from the network which consists of the fixed nodes is fluid. The fixed nodes operate in an asynchronous mode to perform the network self-configuration and transmit data faster to the mobile node which is frequently join and leave the network. When the mobile node leaves the network, the network's operation mode will be synchronous mode to achieve the minimum power consumption, thus the minimum power operation becomes possible.