• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.241-269
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• 2012

Wireless networks composed of multimedia-enabled resource-constrained sensor nodes have enriched a large set of monitoring sensing applications. In such communication scenario, however, new challenges in data transmission and energy-efficiency have arisen due to the stringent requirements of those sensor networks. Generally, congested nodes may deplete the energy of the active congested paths toward the sink and incur in undesired communication delay and packet dropping, while bit errors during transmission may negatively impact the end-to-end quality of the received data. Many approaches have been proposed to face congestion and provide reliable communications in wireless sensor networks, usually employing some transport protocol that address one or both of these issues. Nevertheless, due to the unique characteristics of multimedia-based wireless sensor networks, notably minimum bandwidth demand, bounded delay and reduced energy consumption requirement, communication protocols from traditional scalar wireless sensor networks are not suitable for multimedia sensor networks. In the last decade, such requirements have fostered research in adapting existing protocols or proposing new protocols from scratch. We survey the state of the art of transport protocols for wireless multimedia sensor networks, addressing the recent developments and proposed strategies for congestion control and loss recovery. Future research directions are also discussed, outlining the remaining challenges and promising investigation areas.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.901-908
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• 2011

For the available grid environmental realization, the resource supply PC must have to provide an appropriate security function of their operation environments. SKY@HOME is a kind of the grid computing environments. If this has not supervised by administrator handling smoothly, it is inherently vulnerable state to the security level of the grid environments, because the resource supply PC is not update a security function without delay. It is also have the troublesome problems which have to install of an additional security program for support the appropriate security. This paper proposes an integration security model on the policy-based that provides an update each level according to the situation of the resource supply PC for improving its problems as a security aspect of the SKY@HOME. This model analyzes the security state of the resource supply PC respectively, and then the result is available to provide an appropriate security of the resource supply PC using an integration security model. The proposed model is not need additionally to buy and install the software, because it is provided the security management server oriented service. It is also able to set up the suit security function of a characteristic of the each resource supply PC. As a result, this paper clearly show the participation of resource supply PC improved about 20%.

• KIISE Transactions on Computing Practices
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• v.21 no.6
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• pp.430-435
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• 2015

IP-based, next generation digital broadcast systems transmit DASH segment files. Designed by the DASH system, DASH segment files provide variable quality of contents, while the size of DASH segment files varies even if the file has the same quality. Delays and inefficient use of resources are major challenges in the transmission of variable size DASH segment files in broadcasting systems. Traditional broadcasting transmission systems are designed according to characteristics of physical layer of broadcast, and thus, delay and inefficient resources use is difficult to find. Yet, transmission content quantities continue to rise in the next-generation broadcasting systems (e.g. FHD, UHD (4k, 8k)) with variability of the segments file size as well. Resources for next-generation broadcast are more abundant than traditional broadcast with recent development, but continue to be limited and fixed. Resource delay and inefficiency are important but has not been extensively studied. We propose a transmission structure solution to analyze the delay and efficiency of the resource as each DASH segment file is transmitted, and have further performed simulation studies.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.226-230
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• 2007

This paper proposes a local scheduling method based on user pattern for Volunteer computing project, Korea@Home. It enables Korea@Home participants to run the agent without disturbance. It is devised to prevent user's application from delay while running the agent and decreases the frequency of switching resource between the user and the agent. We analyze the user's patterns of donating computing resource with Korea@Home which is a representative volunteer computing project in Korea. It has contributed the computing power to several applications including climate prediction and virtual screening. It promotes the volunteers to participate continuously without disturbance and increases the potential computing power with non-disturbance scheduling based on user usage pattern for Volunteer Computing.

• ETRI Journal
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• v.26 no.4
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• pp.321-331
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• 2004

In this paper, we propose a new dynamic bandwidth allocation (DBA) algorithm for multimedia services over Ethernet PONs (passive optical networks). The proposed algorithm is composed of a low-level scheduler in the optical network unit (ONU) and a high-level scheduler in the optical line terminal (OLT). The hierarchical DBA algorithm can provide expansibility and efficient resource allocation in an Ethernet PON system in which the packet scheduler is separated from the queues. In the proposed DBA algorithm, the OLT allocates bandwidth to the ONUs in proportion to the weight associated with their class and queue length, while the ONU preferentially allocates its bandwidth to queues with a static priority order. The proposed algorithm provides an efficient resource utilization by reducing the unused remaining bandwidth caused by the variable length of the packets. We also define the service classes and present control message formats conforming to the multi-point control protocol (MPCP) over an Ethernet PON. In order to evaluate the performance, we designed an Ethernet PON system on the basis of IEEE 802.3ah "Ethernet in the first mile" (EFM) using OPNET and carried out simulations. The results are analyzed in terms of the channel utilization, queuing delay, and ratio of the unused remaining bandwidth.

• The Journal of the Acoustical Society of Korea
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• v.17 no.4E
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• pp.28-34
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• 1998

In most switching system, the processing unit is designed to work efficiently even at relatively high loads, but when the offered traffic exceeds a particular level, the rate of completed calls can fall drastically. A single call handled by the switching system consists of a sequence of events or messages that has to be processed by the control unit. The control unit is not only incapable of handling all of the offered calls, but also its call handling capability can drop as the offered load increases. The real time available for call processing is a critical resource that requires careful management. Therefore, the overloading of this resource must be detected by a subscriber in the from of a dial tone delay or an uncompleted call which is either blocked or mishandled. The subscriber may respond by either dialing prematurely or by re-attempting a call. This action can further escalate the processors load, which is spent for uncompleted calls. Unless a proper control is used, the switching system can finally break down. In this paper, we paper, we propose a fuzzy overload detection and control method for switching systems, which can by generating fuzzy rules via fuzzy aggregation networks. Simulation results involving a switching system is given.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1C
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• pp.11-20
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• 2002

In this paper, we propose an efficient quality providing scheme to satisfy a diversify combination of delay bound and loss ratio requirements from users by a predictive dynamic resource allocation method for real-time video applications. For utilizing the network resources more efficiently while meeting the service requirements, we adjust the resources based on the predicted traffic and the currently provided quality level. We developed a simple delayed-packet counter updating scheme for real time QoS monitoring. Simulation results show that our proposed method can provide an accurate and flexible quality control.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.7
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• pp.603-611
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• 2013

In this paper, we propose a new frame structure and the underlying dynamic resource control mechanism to support an integrated service, including a real-time (RT) service that requires to serve the end-to-end delay performance, as well as non-real-time (NRT) service, using Self-Organizing Time Division Multiple Access (SO-TDMA)-based MAC protocol in a multi-hop ad-hoc maritime communication network. The underlying frame structure is dynamically configured by resource allocation to guarantee the average target outage performance of the real-time service. Toward this end, we analyze the average outage probability and its performance is verified for the proposed frame structure by simulation.

• Child Health Nursing Research
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• v.22 no.3
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• pp.163-171
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• 2016

Purpose: This study was done to explore disease factors in children with epilepsy, parental factors and resource factors that are related to parenting stress and identify effects of each factor on parenting stress. Methods: Participants were 131 parents who had children who visited a hospital or were hospitalized due to epilepsy. Data collection was done between September 17 and November 17, 2012, and self-report surveys were used. Results: In Stepwise multiple regression analysis, factors influencing parenting stress in children with epilepsy were marital communication, educational background of parents, parenting efficacy, children's development delay, drug treatment and surgical treatment as a method of epilepsy treatment. These factors explained 34.6% (F=13.22, p<.001) of the variance in parenting stress. Conclusion: The findings indicate that parental factors (educational background of parents and parenting efficacy) and resource factors (marital communication) have higher explanatory power than disease factors of the children. Thus, it is importance to assess the capacity of parents through self-evaluation, and to assess barriers to marital communication when developing parenting stress intervention programs. Furthermore, both parents should be involved in interventions for parenting stress.