• 제어로봇시스템학회논문지
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• 제17권2호
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• pp.190-197
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• 2011

In industrial distributed control systems, sensors collect data from the physical environment periodically and transmit them to the actuators, which process the control operations based on the received data. For the effective operation of the control systems, the data transmitted by the sensors has to be delivered to the actuators reliably within the deadline, and if the message reception rate of the actuators becomes lower than a threshold, then the performance of the control systems drops greatly. This paper suggests a message routing protocol to transmit periodic messages reliably in a distributed control system based on wireless sensor networks. For reliable message transmission, the proposed protocol selects a routing path whose end-to-end message reception rate is the highest before transmitting data messages. The proposed protocol has the capability of maintaining a target message reception rate for each flow. To maintain the required target reception rate, each destination monitors the actual message reception rate periodically and transmits a feedback message to the source if it drops below the target reception rate. On receiving the feedback message, the source tries to find a new path which can satisfy the target rate. The performance of the proposed protocol has been evaluated using simulation and compared with other protocols in terms of the message reception rate, the message delay and delay jitter, and so on. The simulation results show that the proposed protocol has a higher message reception rate and comparable message delay and delay jitter to other protocols. The simulation results also show that the proposed protocol has an ability to adapt well to the dynamic network traffic change.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권3호
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• pp.1152-1167
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• 2018

In this paper, I propose an application layer cooperative congestion control scheme for safety message broadcast in vehicular networks, called CMS, that adaptively controls a vehicle's safety message rate and transmit timing based on the channel congestion state. Motivated by the fact that all vehicles should transmit and receive an application layer safety message in a periodic manner, I directly exploit the message itself as a means of estimating the channel congestion state. In particular, vehicles can determine wider network conditions by appending their local channel estimation result onto safety message transmissions and sharing them with each other. In result CMS realizes cooperative congestion control without any modification of the existing MAC protocol. I present extensive NS-3 simulation results which show that CMS outperforms conventional congestion control schemes in terms of the packet collision rate and throughput, especially in a high-density traffic environment.

• 대한음성학회지:말소리
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• 제64호
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• pp.15-37
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• 2007

The purpose of this paper is to examine the change of the times on the transmission rate of broadcast message. In order to find out the research results, I collected past recorded news tapes and selected 22 radio news out from era of Japanese Imperialism, 1950's, 1960's and contemporary age. Next I measured each announcer's reading rate, and compared change on news-reading rate between present and past approximately 50 years ago. The results of study with such procedures and methods are as follows : the average reporting rate of newscasters in each era is different. From these results, we can easily grasp diachronic change in the transmission rate of broadcast message. Namely, the results show us that present announcers read news faster than the group of past era of Japanese Imperialism by 68%.

• 산업기술연구
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• 제23권A호
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• pp.41-46
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• 2003

Because the quality of a radio link in real environment is generally varied with time, there is a difference between the delay in the real environment and one obtained from the analytic model where a time-varying link model is not used as a link model for a Bluetooth. This paper analyzes the transmission delay of a message in the time-varying radio link model for the Bluetooth. The time-varying radio link is modeled with a two-state Markov model. The mean transmission delay of the message is analytically obtained in terms of the arrival rate of the message, the state transition probability in the Markov model, and the packet error rate.

• 한국경영과학회지
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• 제40권1호
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• pp.35-55
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• 2015

In this research, we analyze the effects of price discounts and scarcity message (both quantity limitation message and time limitation message) on the purchase intention in the smart-phone environment. The purchase intention becomes higher at high discount rate and with scarcity message (both quantity limitation message and time limitation message). We also analyze the moderating effects of consumer's shopping value and distance between the consumer and the store on the effects of price discounts and scarcity message (both quantity limitation message and time limitation message) on the purchase intention. On average, the effects of price discount, time limitation message and quantity limitation message on the purchase intention become the highest levels for consumers pursuing hedonic shopping value. The effects of price discount, time limitation message and quantity limitation message on the purchase intention become higher when they are offered within a short distance between the coupon provider and the target customer.

• Journal of information and communication convergence engineering
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• 제17권4호
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• pp.279-284
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• 2019

This paper presents processing-node status-based message scattering and gathering algorithms for multi-processor systems on chip to reduce the communication time between processors. In the message-scattering part of the message-passing interface (MPI) scatter function, data transmissions are ordered according to the proposed linear algorithm, based on the processor status. The MPI hardware unit in the root processing node checks whether each processing node's status is 'free' or 'busy' when an MPI scatter message is received. Then, it first transfers the data to a 'free' processing node, thereby reducing the scattering completion time. In the message-gathering part of the MPI gather function, the data transmissions are ordered according to the proposed linear algorithm, and the gathering is performed. The root node receives data from the processing node that wants to transfer first, and reduces the completion time during the gathering. The experimental results show that the performance of the proposed algorithm increases at a greater rate as the number of processing nodes increases.

• 한국컴퓨터정보학회논문지
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• 제21권4호
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• pp.17-24
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• 2016

In this paper, we propose a AH LSU(Advanced Hybrid QoS Routing Link State Update) Algorithm that improves the performance of Hybrid LSU(Hybrid QoS Link State State Update) Algorithm with statistical information of flow holding time in network. AH LSU algorithm has had both advantages of LSU message control in periodic QoS routing LSU algorithm and QoS routing performance in adaptive LSU algorithm. It has the mechanism that calculate LSU message transmission priority using the flow of statistical request bandwidth and available bandwidth and include MLMR(Meaningless LSU Message Removal) mechanism. MLMR mechanism can remove the meaningless LSU message generating repeatedly in short time. We have evaluated the performance of the MLMR mechanism, the proposed algorithm and the existing algorithms on MCI simulation network. We use the performance metric as the QoS routing blocking rate and the mean update rate per link, it thus appears that we have verified the performance of this algorithm.

• 한국통신학회논문지
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• 제28권9A호
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• pp.684-693
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• 2003

본 논문에서는 시변 패킷 기반 무선 링크에서 메시지와 패킷의 전송 지연 시간을 분석하였다. 메시지는 베르누이(Bernoulli) 프로세스에 따라 도착하고 생성되는 메시지의 길이는 지수 분포를 가진다고 가정하였다. 또한 시간 변이성을 가지는 무선 링크의 특성을 반영하기 위하여 2-상태 마코프 모델을 사용하여 해석하였다. 이 마코프 모델로부터, 패킷의 도착율과 패킷 전송 서비스 시간, 무선 링크의 평균 PER(packet error rate)의 항으로 패킷의 평균 전송 지연 시간과 평균 큐 길이를 해석적으로 분석하였고, 이러한 패킷의 성능 지표들로부터 메시지의 전송지연 시간 및 큐 길이를 유도하였다. 수치적 결과로부터 시변 패킷 기반 무선 링크의 안정적 동작과 전송 성능을 보장하기 위해서는 PER에 따라 메시지 도착율 및 길이가 제한되어야 한다는 것을 알 수 있었다. 또한 성능에는 각 상태의 머무는 시간보다 PER의 영향이 큼을 알 수 있었다.

• 한국통신학회논문지
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• 제37권4B호
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• pp.278-287
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• 2012

본 논문에서는 NCW 환경에서 Link-16 전술데이터링크를 통해 이미지 정보를 신속 정확하게 전송하여 작전효율을 증대시키기 위한 메시지 패킹 기법을 제안한다. 제안하는 메시지 패킹구조는 기존의 Link-16 메시지와 호환성을 유지하면서 하나의 타임슬롯 내에서 데이터 전송율을 증가시킬 수 있도록 COC(Cyclic shifted Orthogonal Complementary) 웨이브폼의 가변 코드율을 적용하여 주파수 사용 효율을 향상시키고, 특히 동적 TDMA 환경에서 타임슬롯을 연속으로 전송 할 때, 시간 자원 이용률이 높은 패킹구조를 함께 사용하게 되면 동일한 타임슬롯내에 더 많은 데이터를 전송할 수 있도록 하였다. 모의실험을 통해 제안한 방식의 성능 및 우수성을 비교하고 제안 방식의 타당성을 보인다.

• Journal of Communications and Networks
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• 제17권5호
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• pp.482-490
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• 2015

This article exploits spatial diversity for jamming to prevent wiretapping in the extreme case in which an eavesdropper is located near the source and a common jamming signal is unavailable. To address this challenge, the jamming signal is allowed to carry a random binary message. Then, it is proposed that the active intermediate node transmits this jamming signal and the decoding of this signal at both source and destination is physically secured as result of using the physical-layer security method. If the source and the destination securely and correctly decode this jamming message, the source transmits another message which is created from combining its information message and the decoded message using the network-coding method. Therefore, this method prevents the transmissions from being eavesdropped upon by the source-wiretapping.