• Journal of the Korea Society of Computer and Information
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• v.8 no.1
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• pp.84-89
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• 2003

In this Paper, an improved protocol is proposed by supplementing a control station for transmission cycle management. This protocol is proposed to complement the shortcomings of the conventional L-Expressnet protocol which is used for round robin process in bus topology. We analyzed the improved protocol in channel utilization viewpoint and compared the result with that of the conventional protocol. From this result, we showed that the channel utilization of the improved protocol is superior to that of the conventional protocol when a maximum normalized propagation delay is increased.

• Journal of the Korea Society of Computer and Information
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• v.8 no.2
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• pp.106-111
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• 2003

In this Paper, an improved protocol is proposed by supplementing a control station for transmission cycle management and slot-extension function. This protocol is proposed to complement the shortcomings of the conventional L-Expressnet protocol which is used for round robin process in bus topology. We analyzed the improved protocol in channel utilization viewpoint and compared the result with that of the conventional Protocol. From this result, we showed that the channel utilization of the improved protocol is superior to that of the conventional protocol when a maximum normalized propagation delay is increased.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.12
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• pp.18-24
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• 2007

As VLSI technology scales to nano-meter order, relatively increasing global wire-delay has added complexity to system design. Global wire-delay could be reduced by inserting pipeline-elements onto wire but it should be coupled with LIP(Latency Intensive Protocol) to have correct system timing. This combination however, drops the throughput although it ensures system functionality. In this paper, we propose a computation method useful for minimizing throughput deterioration when pipeline-elements are inserted to reduce global wire-delay. We apply this method while placing blocks in the floorplanning stage. When the necessary for this computation is reflected on the floorplanning cost function, the throughput increases by 16.97% on the average when compared with the floorplanning that uses the conventional heuristic throughput-evaluation-method.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.4
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• pp.385-390
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• 2015

Quay cranes are considered core equipment for container terminal operation. However, unmanned operation systems have not as yet been announced due to the technological difficulties of implementation. In this paper, we developed a wireless controller to control a quay crane simulator remotely and conducted its performance test, a first step toward unmanned operation of quay cranes. The communication delay of a developed wireless controller was about 9.4ms on average while that of existing wired controllers was about 5.6ms. The same functions were implemented and tested on a smart phone where the average communication delay was 7.3ms. In addition, to apply the developed system into a real environment, we proposed a network architecture based on IEEE 802.11ac and carried out its performance evaluation. When the distance between two nodes was 50m apart, the throughputs of the TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) were 57Mbps and 189Mbps, respectively. The communication delay of the control data was 9.1ms through the TCP channel. These results reveal the proper working of remote quay crane operation if we adopt the IEEE 802.11ac network.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.513-516
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• 2008

The sensor node's performance is expected to be improved and the price will be largely decreased. As USN-applied field is expanded, multiple application services are expected to be provided through one USN soon. Multiple applications be required a periodic data reporting, consecutive information monitoring, event-driven data and query-based data as the data pattern that USN is delivered. Accordingly, the mechanism which can assure QoS according to each data characteristic is required. In this paper, A proposed protocol apply the duty cycle of S-MAC protocol variably and flexible according QoS level. This method largely reduces the delay on the delay-sensitive traffic, while keeping the energy efficiency.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.2
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• pp.71-78
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• 2008

The sensor node's performance is expected to be improved and the price will be largely decreased. As USN-applied field is expanded, multiple application services are expected to be provided through one USN soon. Multiple applications be required a periodic data reporting, consecutive information monitoring, event-driven data and query-based data as the data pattern that USN is delivered. Accordingly, the mechanism which can assure QoS according to each data characteristic is required. In this paper, A proposed protocol apply the duty cycle of S-MAC protocol variably and flexible according QoS level. This method largely reduces the delay on the delay-sensitive traffic, while keeping the energy efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5B
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• pp.466-474
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• 2003

In this paper, we develope the simulation model for Ethernet passive optical networks (Ethernet-PON) by using OPNET. Ethernet-PON is an emerging access network technology that provides a low-cost method of deploying optical access lines. The simulator uses a Request/Grant TDMA MAC protocol based on IEEE 802.3ah EFM. It also executes registration, ranging and dynamic bandwidth allocation algorithm by exchanging control packets between OLT and ONUs. We have evaluated for success ratio of initial registration process and delay of late registration process. We also have simulated for dynamic TDMA protocol and static TDMA protocol in terms of channel utilization and queueing delay. We expect that this simulator can help to determine various parameters which are considered for designing Ethernet-PON system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.104-113
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• 2000

In this paper, we propose a protocol that makes use of a concept of a meta-group based on propagation trees to deal with duplicated members of the same multicast group. It is shown that, if multicast tree is composed ofthese meta-groups, the depth of the tree can be shortened and the ordering of the multicast that communicatesbetween multiple senders and receivers can be easier. In the protocol, we assign a Designated Manager(DM) toeach meta-group and make each DM do the role of the representative receiver of the meta group. In this Paper,the DM's are supposed to handle ACK and retransmission for the members in the same meta group. Hence, theDM's distribute the ACK from senders, and they can reduce the burden of senders by shortening commit delaytime. We also show, through a simulation analysis, that the new multicast protocol outperforms the existing onesnot only in message costs but also in commit delay times.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1320-1328
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• 2007

In recent year, the popularity of WLAN has generated much interests on improvement and performance analysis of the IEEE 802.11 protocol. In this paper, we analyze two medium access methods of the IEEE 802.11 MAC protocol by investigating the MAC layer packet service times when arrival packet sizes have a general probability distribution. We use the M/G/1/K queueing model to analyze the throughput and the delay performance of IEEE 802.11 MAC protocol in a wireless LAN. We compare the performances of Basic access method and RTS/CTS access method. We take some numerical examples for the system throughput and the queue dynamics including the mean packet delay and packet blocking probability.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.10
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• pp.849-858
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• 2001

One of the important problems which should be solved in the telecontroller control is the time delay problem. In this paper, we propose a method of solving a random time delay problem using QoS(quality of service), and we show not only how to solve an unpredictable time delay problem but also how to compute a maximum time delay that could satisfy a basic assumption of many telecontroller methods. Using our proposed method, it is find that we can offer more stable time delay in telecontroller than using TCP and UDP.