• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.05a
• /
• pp.621-624
• /
• 2017

In this paper, we propose a protocol synchronizing to packet trains in a underwater acoustic networks with limitations such as long propagation delay, low data rate, high packet loss. The proposed protocol employs an one-way communication scheme to calculate packet arrival time differences of consecutively transferred packets and minimizes uncertain variation effect of long propagation delay. Simulation results shows the superiority of our protocol, compared with a previously proposed one under the given network conditions.

• Journal of Communications and Networks
• /
• v.15 no.6
• /
• pp.606-613
• /
• 2013

This paper proposes a complete solution of a contention-based medium access control in wireless local networks to provide station level quality of service guarantees in both downstream and upstream directions. The solution, based on the mature distributed coordination function protocol, includes a new fixed contention window backoff scheme, a tuning procedure to derive the optimal parameters, a super mode to mitigate the downstream bottleneck at the access point, and a simple admission control algorithm. The proposed system guarantees that the probability of the delay bound violation is below a predefined threshold. In addition, high channel utilization can be achieved at the same time. The numerical results show that the system has advantages over the traditional binary exponential backoff scheme, including efficiency and easy configuration.

• Journal of Korean Institute of Industrial Engineers
• /
• v.40 no.1
• /
• pp.135-139
• /
• 2014

In a connection-oriented packet switching network, the data communication starts after a virtual circuit is established between source and destination. The virtual circuit establishment time includes the queue waiting times in the direction from source to destination and the other way around. We use this two-way queueing delay to evaluate scheduling policies of a packet switching processor through simulation studies. In this letter, we also suggest user testing functions for the packet switching processor to manage virtual circuits. By detecting error causes, the user testing helps the packet switching processor provide reliable connection-oriented services.

• Journal of Information Processing Systems
• /
• v.15 no.5
• /
• pp.1029-1035
• /
• 2019

In recent years, artificial intelligence (AI) services have become one of the most essential parts to extend human capabilities in various fields such as face recognition for security, weather prediction, and so on. Various learning algorithms for existing AI services are utilized, such as classification, regression, and deep learning, to increase accuracy and efficiency for humans. Nonetheless, these services face many challenges such as fake news spread on social media, stock selection, and volatility delay in stock prediction systems and inaccurate movie-based recommendation systems. In this paper, various algorithms are presented to mitigate these issues in different systems and services. Convolutional neural network algorithms are used for detecting fake news in Korean language with a Word-Embedded model. It is based on k-clique and data mining and increased accuracy in personalized recommendation-based services stock selection and volatility delay in stock prediction. Other algorithms like multi-level fusion processing address problems of lack of real-time database.

• International Journal of Internet, Broadcasting and Communication
• /
• v.15 no.1
• /
• pp.157-163
• /
• 2023

Recently, as businesses and data types become more complex and diverse, efficient data analysis using machine learning is required. However, since communication in the cloud environment is greatly affected by network latency, data analysis is not smooth if information delay occurs. In this paper, SPT (Safe Proper Time) was applied to the cluster-based machine learning data analysis agent proposed in previous studies to solve this delay problem. SPT is a method of remotely and directly accessing memory to a cluster that processes data between layers, effectively improving data transfer speed and ensuring timeliness and reliability of data transfer.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.47 no.3
• /
• pp.1-7
• /
• 2024

In an influential paper, Choi and Kim (2010) derived waiting times in an M/M/1 queuing model under net neurality and under prioritization. In this short paper, we argue that the waiting times of content transmission that Choi and Kim (2010) derived by using the M/M/1 gueuing model under the non-preemptive priority rule are miscalculated. We provide corrected waiting times in the M/M/1 queuing model in the prioritization case. We also show that this correction does not affect their main results on the delay time and the incentive to invest in the network capacity qualitatively.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.842-847
• /
• 2005

This paper proposes a novel real-time EMG pattern recognition for the control of a multifunction myoelectric hand from four channel EMG signals. To cope with the nonstationary signal property of the EMG, features are extracted by wavelet packet transform. For dimensionality reduction and nonlinear mapping of the features, we also propose a linear-nonlinear feature projection composed of PCA and SOFM. The dimensionality reduction by PCA simplifies the structure of the classifier, and reduces processing time for the pattern recognition. The nonlinear mapping by SOFM transforms the PCA-reduced features to a new feature space with high class separability. Finally a multilayer neural network is employed as the pattern classifier. We implement a real-time control system for a multifunction virtual hand. From experimental results, we show that all processes, including virtual hand control, are completed within 125 msec, and the proposed method is applicable to real-time myoelectric hand control without an operation time delay.

• Proceedings of the KIEE Conference
• /
• 2004.07d
• /
• pp.2161-2163
• /
• 2004

This paper focuses on congestion control for ATM network with uncertain time-variant delays. The time-variant delays can be distinguished into two distinct components. The first one that is represented by time-variant queueing delays in the intermediate switches is occurred in the return paths of RM cells. The next one is a forward path delay. It is solved by the VBR Model which quantifies the data propagation from the sources to the switch. Robust $H_{\infty}$ control is studied for solving congestion problem with norm-bounded time-varying uncertain parameters. The suitable robust $H_{\infty}$ controller is obtained from the solution of a convex optimization problem including terms of LMIs.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2005.04a
• /
• pp.161-165
• /
• 2005

In order to produce an optimal traffic cycle. We must first check how many waiting cars are at the lower intersection, because waiting queue is bigger than the length of upper traffic intersection. Start up delay time and vehicle waiting time occurs. To reduce vehicle waiting time, in this paper, we present an optimal green time algorithm using fuzzy neural network. Through computer simulation has been proven to be improved average vehicle speed than fixed traffic signal light which do not consider different intersection conditions.

• Journal of Institute of Control, Robotics and Systems
• /
• v.16 no.4
• /
• pp.403-410
• /
• 2010

The switched Ethernet has many features for real-time communications such as providing traffic isolation, large bandwidth, and full-duplex links, and so on. The switched Ethernet, however, cannot guarantee the timely delivery of a real-time message because message delay increases when collisions occurs at the output ports and message loss can even occur due to the overflow at the output buffer. Recently, many research efforts have been done to use the switched Ethernet as an industrial control network. In the industrial control network, sensors periodically sense the physical environment and transmit the sensed data to an actuator, and the periodic messages from sensors to actuators have typically real-time requirements such that those messages must be transmitted within their deadlines. This paper first suggests a feasible condition for EDF (Earliest Deadline First)-based scheduling of periodic messages on a synchronized switched Ethernet and a message scheduling algorithm which satisfies the proposed feasible condition. Pedreiras, et al. [10] suggested a feasible condition for message scheduling on the Ethernet (shared media Ethernet), but there has been no research result on the scheduling condition on the switched Ethernet until now. We compared the real-time message scheduling capacity between the Ethernet and the switched Ethernet by simulation. The simulation result shows that the message scheduling capacity of the Ethernet has almost remained constant as the number of nodes on the network increases, but, in the case of the switched Ethernet, the message scheduling capacity has increased linearly according to the number of nodes on the network.