• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12B
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• pp.719-727
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• 2007

The Wireless Mesh Network technology is able to provide an infrastructure for isolated islands, in which it is difficult to install cables or wide area such as battlefield of armed forces. Therefore, Wireless Mesh Network is frequently used to satisfy needs for internet connection and active studies and research on them are in progress However, as a result of increase in number of hops under hop-by-hop communication environment has caused a significant decrease in throughput and an increase in delay. Considering the heavy traffic of real-time data, such as voice or moving pictures to adaptive WMN, in a military environment, it is restricted for remote units to have their Mesh Node to get real-time services. Such phenomenon might cause an issue in fairness. In order to resolve this issue, the Location-based Packet Scheduling Scheme, which can provide an fair QoS to each mesh node that is connected to each echelon's AP and operates based on WRR method that gives a priority to emergency message and control packet. The performance of this scheme is validated.

• Korea Journal of Hospital Management
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• v.15 no.3
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• pp.47-68
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• 2010

One of the important complaint factors by the patients using medical institutions is various kinds of waiting time. This research is about the causal relationships among waiting time(application of waiting time, perceived of waiting time, fairness of waiting, explanation of the delay, acceptance possibility), service values, and customer satisfaction. The subjects for this study were 256 out-patients currently using seven general hospitals in the Busan area. The findings of the empirical analysis are as follows: First, the good application of waiting time or fair waiting time procedure didn't actually affect perceived waiting time. Second, though the application of waiting time didn't affect acceptance possibility, the fair procedure of waiting time had an affirmative effect on acceptance possibility. Third, even when there was enough explanation about the need to wait, it could shorten perceived waiting time but failed to get sufficient sympathy or agreement from the patients. Fourth, the possibility of acceptance following the sufficient sympathy of patients had an effect on shortening perceived waiting time. Fifth, perceived waiting time lowered customer satisfaction, but had no negative effect on service values. Finally, the ranges of acceptance possibility by the patients were found to increase customer satisfaction and maximize service values. In conclusion, every medical institution needs to focus on, first of all, shortening waiting time for more customer satisfaction and improved service values.

• Journal of Korea Multimedia Society
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• v.9 no.2
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• pp.189-196
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• 2006

This paper proposes a priority based AOI management model as a method to effectively process message traffic for collaboration in virtual environments. Where message traffic reaches the maximum capacity of the message replay server in DVE, some of the events might be delayed to be updated at the remote clients. Because existing AOI models depend only on the occurrence time of events, they have a problem that more important events in the context might be processed later than less serious ones. Close Interactions with other participants are relatively more important than simple events which happen at a distance from the participant. This study classifies the priorities of events according to the degree of interest, and proposes a method to reduce processing delay time of events highly interested by a user. The proposed model offers a way to effectively utilize limited capacity of a server using a priority queue mechanism, which is able to handle different kinds of events. To prevent from starvation of simple events and to give fairness to the proposed algorithm, event occurrence time is also considered as well as degree of interest when processing events.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9B
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• pp.1272-1280
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• 2010

WFQ (Weighted Fair Queuing) provides not only fairness among traffic flows in using bandwidth but also guarantees the Quality of Service (QoS) that individual flow requires, which is why it has been applied to the resource reservation protocol (RSVP)-capable router. The RSVP allocates an enough resource to satisfy both the rate and end-to-end delay requirements of the flow in condition of no packet loss, and the WFQ guarantees those QoS requirements with the allocated resource. In a practice, however, most QoS-guaranteed services, specially the Voice of IP, allow a few percent of packet loss, so it is strongly desired that the RSVP and WFQ make the best use of this allowable packet loss. This paper enhances the WFQ to allow packet loss and investigates its performance. The performance evaluation showed that allowing the packet loss of 0.4% can improve the flow admission capability by around 40 percent.

• Convergence Security Journal
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• v.8 no.2
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• pp.57-62
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• 2008

In this paper, we suggest new fast recovery mechanism in RPR network, in case of node addition or removing by exterior attack. A RPR network recovery time is consist of two. Failure detecting time and reporting time are that. In this paper we propose fast recovery mechanism that can reduce each time. In a Legacy recovery mechanism, To report node's state, rpr node transmit protection messages. But interval of this protection messages increase exponentially. Thus A transmission failure of protection message cause delay of reporting of network state. Therefore we propose new node state reporting mechanism that put a node state in type b fairness message. And We also suggest fast failure detecting mechanism.

• Journal of the Korea Society of Computer and Information
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• v.16 no.3
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• pp.149-156
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• 2011

In wireless multi-hop network, many applications need multicast communication where the group leader needs to send data to all members of the group. Multicast routing provides a balanced, efficient, and fairness network environment for the group members. However, large load for transmission management to leader node and signal interference between several paths for multi-hop links always took long transmission delay and low throughput efficiency. In this paper, we propose a Zone-based Hierarchical Multicast Routing Protocol (ZHMP). This routing protocol is designed based on zone routing schemes, where proactive routing is applied for intra-zone node level multicasting and reactive routing is used for searching inter-zone paths. By each hierarchical and independent multicast working in separated zones, load of multicast source node will be distributed by several zone-level routings for a better load balance and signal interference between each multi-hop paths will be resisted for a maximum multicast throughput.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.3176-3183
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• 2011

Traffic and congestion control in the wireless sensor network is an important parameter that decides the throughput and QoS (Quality of Service). This paper proposes a transmission rate priority-based traffic control scheme to serve digital contents streaming in wireless sensor networks. In this paper, priority for transmission rate decides on the real-time traffic and non-real-time with burst time and length. This transmission rate-based priority creates low latency and high reliability so that traffic can be efficiently controlled when needed. Traffic control in this paper performs the service differentiation via traffic detection process, traffic notification process and traffic adjustment. The simulation results show that the proposed scheme achieves improved performance in delay rate, packet loss rate and throughput compared with those of other existing CCF and WCA.

• Journal of the Korea Society of Computer and Information
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• v.7 no.3
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• pp.80-91
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• 2002

A general goal of the AT%(Asynchronous Transfer Mode) network is to support connect across various network. On ATM networks, ABR services are provided using the remained ban after allocation CBR and VBR traffic. Realtime services such as transmitting audio or video data may be provided using CBR ado VBR which have a constrained transmission delay, but in these cases, the communications bandwidth may be wasted. In this paper a simulation has been performed to compare and evaluate the performance between the ERICA(Explicit Rate Indicate Avoidance) and EPRCA(Enhanced Proportional Rate Control Algorithm) switches which use Explicit Rate switch algorithm for ABR switch. The variation of the ACR at the source end system, the queue length, the utilization rate of the link bandwidth and the share fairness at the transient and steady states are used as the evaluation criteria for the simulation. As a result of simulation, ERICA algorithm switch was ten times long compared to ERPCA switch to achieve assigned fair share. so EPRCA switch is superior to ERICA about load response. For Fair share and stability, ERICA switch is excellent to EPRCA switch.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.4
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• pp.84-91
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• 2011

Recently, WBAN(Wireless Body Area Network) which has progressed standardization based on IEEE 802.15.6 standardization is a network for the purpose of the short-range wireless communications within around 3 meters from the inner or outer human body. Effective QoS control technique and data efficient management in limited bandwidth such as audio and video are important elements in terms of users and loads in short-range wireless networks. In this paper, for high-speed WBAN IEEE 802.15.6 standard, the dynamic allocation to give an efficient bandwidth management and weighted fair queueing algorithm have been proposed through the adjustment of the super-frame about limited data and Quality of Service (QoS) based on the queuing algorithm. Weighted Fair Queueing(WFQ) Algorithm represents the robust performance about elements to qualitative aspects as well as maintaining fairness and maximization of system performance. The performance results show that the dynamic allocation expanded transmission bandwidth five times and the weighted fair queueing increased maximum 24.3 % throughput and also resolved delay bound problem.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.11 s.353
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• pp.128-140
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• 2006

In the IEEE 802.16 Wireless MAN standard specifies the air interface of fixed point-to-multipoint broadband wireless access systems providing multiple services. Among the service classes supported between the base station and subscriber stations in the wireless MAN, the best effort service class is ranked on the lowest position in priority and is assisted by a MAC scheme based on reservation ALOHA. The wireless MAN standard, however, does not reveal every detail of the MAC scheme but only describes the skeleton of the MAC scheme. Focusing on the amount of resource that a subscriber demands by a request and the amount of resource that the base grants to a request we thus present a number of resource demand rules and resource grant rules. Also, we construct a candidate MAC scheme by implanting a pair of resource demand and grant rules into the skeleton of the MAC scheme. Meanwhile a difficult situation for the best effort service is expected wherein only scarce resource is available after most of the resource is already preempted by other services. Perceiving such a situation, we evaluate the throughput and delay performance of each candidate MAC scheme. Especially we develop an analytical method to approximately calculate the throughput in the saturated environment. From the numerical results, we observe that the candidate MAC scheme which adopts the non-gated exhaustive demand rule paired with the full grant rule attains superior performance at the expense of the fairness.