• 제어로봇시스템학회논문지
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• 제18권8호
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• pp.768-773
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• 2012

Packet loss compensation techniques are increasingly important to stable remote control over wireless communication in WNCS (Wireless Networked Control Systems). Its time varying channels, limited bandwidth, interference, and poor signal not only leads to packet loss or latency, but also can negatively affect performance and system stability. This paper presents a compensation technique exploiting an EWMA (Exponentially Weighed Moving Average)-based value estimator to clarify the influence of packet loss on the overall WNCS behavior. As an example of actuator to be remotely controlled, a rotary-type inverted pendulum has been considered, and modeled. Performance evaluation results through Matlab/Simulink and Truetime co-simulation confirm the superiority of the proposed value estimation method over previous approaches.

• 제어로봇시스템학회논문지
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• 제9권10호
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• pp.789-797
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• 2003

An implementation scheme and some improvements are proposed to adopt public-licensed operating system, Linux and de-facto world-wide network standard, TCP/IP into the field of behavior-based autonomous mobile robots. To demonstrate the needs of scheme and the improvement, an analysis is performed on a server/client communication problem with real time Linux previously proposed, and another analysis is also performed on interactions among TCP/IP communications and the performance of Linux system using them. Implementation of behavior-based control architecture on real time Linux is proposed firstly. Revised task-scheduling schemes are proposed that can enhance the performance of server/client communication among local tasks on a Linux platform. A new method of TCP/IP packet flow handling is proposed that prioritizes TCP/IP software interrupts with aperiodic server mechanism as well. To evaluate the implementation scheme and the proposed improvements, performance enhancements are shown through some simulations.

• Journal of Information Processing Systems
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• 제16권5호
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• pp.1095-1104
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• 2020

This paper introduces a design scheme of intelligent gas valve management and service system based on Internet. This scheme adds sensor and general packet radio service (GPRS) modules to the traditional gas valve and establishes communication connection between gas valve and the server through wireless packet communication technology, which makes the traditional gas valve have the networking ability. Compared with the traditional gas valve management and service business, the method proposed in this paper is more convenient and efficient.

• 한국정보통신학회논문지
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• 제5권4호
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• pp.645-652
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• 2001

본 논문은 근거리 차량간 통신(IVC)에서 첨단차량도로시스템(AVHS)의 플래툰 주행에 적합한 One-Ray Rician 채널 모델을 적용하여 간섭신호에 강한 장점을 지닌 60GHz 밑리미터파에서 패킷 오율 특성을 분석하였다. 차후에 사용자의 욕구 증대에 따른 멀티미디어 서비스를 만족시키기 위해서 Convolution 부호화 기법과 MRC 다이버시티 수신 기법을 동시에 적용하였으며 그에 따른 DS-CDMA/QPSK System의 패킷 오율 특성을 분석하였다.

• 한국군사과학기술학회지
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• 제16권6호
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• pp.819-827
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• 2013

Compared to legacy frequency hopping communications, future radio communications are required the secure and high data rate, ad-hoc network communication. In this paper, we have designed the network communication structure on the frequency hopping mode, and analyzed the performance of synchronization on the frequency hopping network radio systems. The design results are shown the initial sync. phase of approximately 9 hops and the traffic packet phase of approximately 30 hops. Also, we have simulated the performance on the communication conditions which are carrier bandwidth of 50kHz, user data rate of 64kbps and OQPSK modulation scheme in AWGN. In the simulation, we analyzed the correlation and the performance of synchronization success. The result of simulation show 99% probability for synchronization success at $E_b/N_o$ -4dB.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.396-405
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• 2009

열차제어 지상신호시스템에서 핵심적인 철도보안기능을 수행하는 연동장치는 철도산업의 안전성 확보 지침에 따라 높은 안전성과 신뢰성을 갖추어야만 한다. 따라서 연동장치는 높은 안전성과 신뢰성을 달성할 수 있도록 실시간 운영체제 및 그 구성 하드웨어의 랜덤 고장에 대처하기 위한 Fail-Safe형 다중 제어시스템으로 구성된다. 이러한 구성에서는 운영자 인터페이스를 포함한 다양한 장치와의 메시지 교환을 위한 인터페이스 가능을 구현하기 어려운 특성이 존재한다. 본 논문에서는 연동장치와 상위 인터페이스 설비간의 통신기능을 구현하기 위한 Dual Ethernet 네트워크 구성 및 DPST (Dual Packet Seamless Transfer) 통신 프로토콜을 제안한다. 제안된 시스템의 구성에서는 특정 네트워크 장비의 랜덤 고장이나 통신오류에 강인한 특성을 보이며 통신채널의 장애를 검출할 수 있는 기능이 추가되어 설비의 유지보수에 효과적인 정보로 활용될 수 있음을 실험적으로 검증한다. 제안된 네트워크 구성 및 운영 프로토콜을 현대제철 전용철도용 전자연동장치에 구현하고 그 성능과 특성을 유럽표준규격 EN50159의 지침을 토대로 타당성을 분석한다.

• 한국군사과학기술학회지
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• 제14권2호
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• pp.222-231
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• 2011

In this paper, we have proposed a method which can make it possible to stably transmit and receive data like the ARC-164 radio frequency hopping environment as a S/W packet modem with PSK modulation. This is a method that the S/W packet modem with PSK digital modulation and the use of PC sound cards change over from data to voice signals and then transmit/receive data. We confirmed not only that it is possible to solve the slow speed communication with the use of sending data through multi-channels and PSK modulation that has the ability to methodically improve transmission rates, but also that it is possible to send the state of frequency hopping stably. In conclusion, we've confirmed both tactical values that though the transmission rate may be a tad slow, a state of frequency hopping of more than 94% confidence plus voice and data can be sent via radio at the same time. In this paper, the proposed S/W packet modem is only an implemented S/W component, so when we apply it to aircraft that we don't consider EMC problems with, then we have the advantage of a wider use of conventional UHF/VHF/HF radio that is possible to voice communication. If we recognize these operational requirements, we can apply for a lot of field equipment efficiently.

• 디지털산업정보학회논문지
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• 제9권2호
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• pp.63-71
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• 2013

WAVE(Wireless Access for Vehicular Environment) System is a communication technology to monitor system failure and vehicle functions and management services to prevent possible incidents of driving a vehicle. In this paper, we have designed and implemented the mutual message processing through parameter between WME management module that manages WAVE system and MLME that manages the upper layer MAC(Media Access Control) module. Also, in order to verify the validity, we have carried out experiments to compare the speed of data processing by dividing data of 1Mbyte, 2Mbyte, 3Mbyte into the packets of 2KByte and 4KByte. Experiments data processing speed of 2KByte packet were shown about 173.62ms in 1MByte, 2MByte about 352.61ms, 3MByte about 550.13ms and, data processing speed of 4KByte packet, 1MByte approximately 87.56ms, 2MByte about 177.94ms, 3MByte about 277.18ms. Therefore, in WAVE system, the mutual messages processing through the parameters between WME and MLME module can be utilized in the various service of ITS(Intelligent Transportation Systems) depending on the speed of data processing.

• Journal of information and communication convergence engineering
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• 제8권6호
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• pp.660-664
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• 2010

This paper proposes a backoff control scheme for guaranteeing fair packet transmissions in TDMA wireless networks. In order to maximize the system performance, the number of packets transmitted in a frame should be kept at a proper level. In the proposed scheme, the base station calculates the packet transmission probability according to the offered loads and then broadcasts to all the mobile stations. Mobile stations attempt to transmit a packet with the received probability. Simulation results show that the proposed scheme can offer better system throughput and delay performance than the conventional one regardless of the offered loads.

• Journal of information and communication convergence engineering
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• 제3권2호
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• pp.90-92
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• 2005

As the result of the study shows, Round Robin Algorithm allows servers to ensure definite traffic distribution, unless incoming data loads differ much. Although error levels are high in some cases, they were eventually alleviated by repeated tests for a long period of time. The study uses two software packages (Packet Capture and Round Robin Test Package) to check packet volume from Virtual Network Structure (data generator, virtual server, Server 1, 2, 3), and finds out traffic distribution toward Server 1, 2, and 3. The functions of implemented Round Robin Load Balancing Monitoring System include round robin testing, system monitoring, and graphical indication of data transmission and packet volume.