• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4878-4883
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• 2015

The IP Multimedia Subsystem(IMS) is a framework that provides access to the content of Internet and Telecom services anytime and anywhere with guaranteed Quality of Service(QoS) and manageability by separating control functions from bearer and services. The Service Delivery Platform(SDP) provides common interfaces and protocols to deploy existing or new services in an efficient way. Therefore SDP over IMS plays a role of bridge between established network and new IMS network by simplifying the interaction among application services. In order to enrich the multimedia network communication, we try to deploy the Push-to-talk over Cellular(PoC) service which is considered as the outstanding and distinguished half-duplex Voice over IP(VoIP) application service among deployable candidate services over mobile network. In this paper we investigate the advantages of PoC service and PoC architecture firstly, and then focus on the its practical implementation for the prototype to validate the feasibility of its deployment and realization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.5
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• pp.425-432
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• 2014

The Enhanced Distributed Channel Access (EDCA) function of IEEE 802.11e standard defines contention window (CW) for different Access Category (AC) limits to support Quality-of-Service (QoS). However, it have been remained the problem that the collision probability of transmission is increasing in congested network. Several different solutions have been proposed but the collision occurs among same priority queue within the same station to compete the channel access. This paper presents an APCA (Advanced Priority Collision Avoidance) algorithm for EDCA that increases the throughput in saturated situation. The proposed algorithm use reserved field's bits of FC(Frame Control) using IEEE 802.11e standard's RTS/CTS (Request to Send / Clear to Send) mechanism to avoid data collision. The simulation results show that the proposed algorithm improves the performance of EDCA in packet loss. Using Jain's fairness index formula, we also prove that the proposed APCA algorithm achieves the better fairness than EDCA method under network congested condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.877-885
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• 2005

The Home Phoneline Networking Alliance (HomePNA) 2.0 technology can establish a home network using existing in-home phone lines, which provides a channel rate of 4-32 Mbps. HomePNA 2.0 Medium Access Control(MAC) protocol adopts an IEEE 802.3 Carrier Sense Multiple Access with Collision Detection (CSMA/CD) access method, Quality of Service(QoS) algorithm, and Distributed Fair Priority Queuing(DFPQ) collision resolution algorithm. In this paper, we propose some mathematical models about the important elements of HomePNA 2.0 MAC protocol performance, which are Saturation Throughput, Packet Delay and Packet Jitter. Then, we present an overall performance analysis of HomePNA 2.0 MAC protocol along with simulations.

• Journal of Advanced Navigation Technology
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• v.11 no.4
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• pp.479-484
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• 2007

This paper explains the design and implementation of the FRA(Fault Recovery Agent). FRA is a system that is suitable for recovering software error for multimedia distance education based on home network environment. In terms of distributed multimedia systems, the most important catagories for quality of service are a timeless, volume, and reliability. In this paper, we discuss a method for increasing reliability through fault tolerance. This paper explains a performance analysis of an error recovery system running on distributed multimedia environment using rule-based DEVS modeling and simulation techniques. In DEVS, a system has a time base, inputs, states, outputs, and functions. The proposed method is more efficient than the other method in comparison with error ration and processing time.

• Journal of Navigation and Port Research
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• v.30 no.3 s.109
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• pp.211-217
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• 2006

In recent years, the pileup of world ports is deepening as time goes by due to China effect and continuous increase of world trade volume. The shipping companies try to reduce their shipping cost by using mega vessels in the ports. Shipping companies consider most of the ships turnaround time as a critical factor when selecting a calling port for reducing cost. This paper will suggest how we can guarantee terminal QoS like ship waiting time ratio and ship residing time applying RFID(Radio Frequence IDentification) technology, raising up rapidly as a fundamental solution of new growing industry to port information system. Also, lead time of whole port logistics can be decreased for reduction of loading & discharging time and result from productivity improvement of Twin-lift G/C(Gantry Crane} as applying RFID technology to terminal operation. The purpose of this paper suggests that the new business model of U-Port which port QoS can be guaranteed using RFID based RTLS technology.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.151-158
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• 2010

In line with the requirement of appropriate protocol support for such mission-critical wireless sensor network (WSN) applications as patient monitoring, we investigate the framework for designing medium access control (MAC) schemes. The data traffic in medical systems comes with inherent traffic heterogeneity as well as strict requirement of reliability according to the varied extents of devise-wise criticality in separate cases. This implies that the quality-of-Service (QoS) issues are very distinctly delicate requiring specialized consideration. Besides, there are features in such systems that can be exploited during the design of a MAC scheme. In a monitoring or routine surveillance application, there are degrees of regularity or predictability in traffic as coordinated from a node of central control. The coordinator thus takes on the role of marshaling the resources in a neighborhood of nodes deployed mostly for upstream traffic; in a collision-free scheme, it schedules the time slots for each superframe based on the QoS specifications. In this preliminary study, we identify the key artifacts of such a MAC scheme. We also present basic performance issues like the impact of superframe length on delay incurred, energy efficiency achieved in the network operation as obtained in a typical simulation setup based on this framework.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.8
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• pp.1004-1010
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• 2019

In the EH-WSN (Energy harvesting wireless sensor network), a MAC (medium access control) protocol is required to select a relay node considering the power status of a node. Existing EH-WSN studies emphasize the power aspect, so it does not consider the QoS like the urgency of the sensed data. The required power and transmission delay must be changed according to the urgency so that the medium access control according to the data QoS can be performed. In case of relay node, relaying data without consideration of data urgency and node power may cause delay due to power shortage in case of urgent data. In this paper, we designed a MAC protocol that minimizes the power shortage that can occur during emergency data generation. For this, relay node requirements are set differently according to the urgency of data. The performance was analyzed through simulation. Simulation results show the reduced latency and improved reliability of urgent data transmission.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.459-465
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• 2014

Recently, multimedia data transmission becomes important issues in the wireless sensor network. For the multimedia data transmission in wireless sensor network, QoS (Quality of service) is an important factor to determine the system performance. AODV algorithm is one of the widely used algorithm for wireless ad-hoc environment. In AODV, the destination node selects the route with the smallest hop count. Since AODV only considers the hop count, the selected route could have low channel condition, and degrade QoS. In this paper, we propose a modified AODV algorithm that considers the successful transmission rate of each link. The proposed algorithm regards the number of retransmission which can be obtained from the successful transmission rate as the hop count, and applies the modified hop count to AODV. The advantage of the proposed algorithm is that the modified AODV can support QoS without significant change of the conventional algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.9
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• pp.3159-3176
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• 2014

This work presents an analysis of the buffer features of an access router, especially the size, the impact on delay and the packet loss rate. In particular, we study how these features can affect the Quality of Service (QoS) of multimedia applications when generating traffic bursts in local networks. First, we show how in a typical SME (Small and Medium Enterprise) network in which several multimedia flows (VoIP, videoconferencing and video surveillance) share access, the upgrade of the bandwidth of the internal network may cause the appearance of a significant amount of packet loss caused by buffer overflow. Secondly, the study shows that the bursty nature of the traffic in some applications traffic (video surveillance) may impair their QoS and that of other services (VoIP and videoconferencing), especially when a certain number of bursts overlap. Various tests have been developed with the aim of characterizing the problems that may appear when network capacity is increased in these scenarios. In some cases, especially when applications generating bursty traffic are present, increasing the network speed may lead to a deterioration in the quality. It has been found that the cause of this quality degradation is buffer overflow, which depends on the bandwidth relationship between the access and the internal networks. Besides, it has been necessary to describe the packet loss distribution by means of a histogram since, although most of the communications present good QoS results, a few of them have worse outcomes. Finally, in order to complete the study we present the MOS results for VoIP calculated from the delay and packet loss rate.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.513-516
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• 2005

SVC(Scalable Video coding) is the standardization of MPEG that aims to support multi spatial, temporal, and quality layers. We can support the video service guaranteeing the QoS in varied network circumstance by using SVC bitstream. In this paper, we propose the real-time SVC bitstream extractor that is able to extract the bitstream with varied frame rate and SNR quality in real-time. To do, extraction processing needs to be performed by GOP unit. As well , essential bitstream information for real-time extraction is aquired before doing extraction process. The proposed method is implemented by using JSVM 2.0. Experimental results show that the proposed method is valid.