• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.6A
• /
• pp.484-493
• /
• 2009

For the flexible frequency utilization, cognitive radio technique has been prominently considered. The most important requirement in cognitive radio networks is to protect the communications of primary users. Spectrum sensing task by secondary users should be seriously considered in cognitive radio networks, since the spectrum sensing process makes their current quality of service worse. In this paper, we propose the channel sensing scheduling method that keeps the requirements for protecting the primary and guarantee the secondary user's quality of service as possible. The quality of service of secondary user is analyzed in terms of packet delay and loss while the protection-requirements in terms of sensing interval and sensing time predefined. In numerical analysis, we can get appropriate parameters which guarantee QoS in various environment. And simulation results show that this method can improve the performance, delay and the number of transmitted packets against consecutive sensing method.

• The KIPS Transactions:PartA
• /
• v.9A no.4
• /
• pp.603-614
• /
• 2002

Delivery efficiency of e-learning media can be influenced by authoring processes. Generally, a moving picture recorded by video camera can be delivered to student by multimedia streaming service, using media server technology. A e-learning media authored by lecture authoring tool is played in a student application by download-based delivery system. Recently, some animation know-how are applied to author e-learning media by hand-operation. In this paper, we suggest a client-based streaming service for the e-leaning media consists of media files and integration data The lecture of e-learning media nay be divided into some time-based small blocks. Each blocks can be located distributed site. The student system gather those blocks by download-scheduling. This is a valid method for QoS guarantee streaming services. In addition to our study, lecturers can author composite e-learning media includes media files and dynamic web pages simply, The distributed e-learning media files of our study is managed by multi-author and updated rapidly.

• Korean Journal of Social Welfare Studies
• /
• v.47 no.4
• /
• pp.93-120
• /
• 2016

This study aims to elaborate differences of demand and supply in welfare service delivery upon regions. For this purpose, in-depth interviews were conducted with 15 welfare bureaucrats from Dong offices among largest and smallest portions of recipients in Seoul. The results indicated that there were significant differences in the proportion of welfare bureaucrats versus welfare recipients (11-450 households) of the National Basic Livelihood Guarantee System, the amount of available private sector resources, and the difficulty of providing visitation counseling upon regions. Research implications were discussed further to address regional disparities of welfare services.

• Journal of Communications and Networks
• /
• v.11 no.2
• /
• pp.175-186
• /
• 2009

A new medium access control (MAC) scheme embedding physical channels into multiband carrier sense multiple access/collision avoidance (CSMA/CA) networks is proposed to provide strict quality of service (QoS) guarantee to high priority users. In the proposed scheme, two priority classes of users, primary and secondary users, are supported. For primary users physical channels are provided to ensure strict QoS, whereas secondary users are provided with best-effort service using CSMA/CA modified for multiband operation. The performance of the proposed MAC scheme is investigated using a new multiband CSMA/CA Markov chain model capturing the primary user activity and the operation of secondary users in multiple bands. The throughput of secondary users is obtained as a function of the primary user activity and other CSMA/CA parameters. It is shown that the new MAC scheme yields larger throughput than the conventional single-band CSMA/CA when both schemes use the same bandwidth.

• ETRI Journal
• /
• v.29 no.2
• /
• pp.201-211
• /
• 2007

This paper focuses on the scheduling problem with the objective of maximizing system throughput, while guaranteeing long-term quality of service (QoS) constraints for non-realtime data users and short-term QoS constraints for realtime multimedia users in multiclass service high-speed uplink packet access (HSUPA) systems. After studying the feasible rate region for multiclass service HSUPA systems, we formulate this scheduling problem and propose a multi-constraints HSUPA opportunistic scheduling (MHOS) algorithm to solve this problem. The MHOS algorithm selects the optimal subset of users for transmission at each time slot to maximize system throughput, while guaranteeing the different constraints. The selection is made according to channel condition, feasible rate region, and user weights, which are adjusted by stochastic approximation algorithms to guarantee the different QoS constraints at different time scales. Simulation results show that the proposed MHOS algorithm guarantees QoS constraints, and achieves high system throughput.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.350-353
• /
• 2004

The increasing use of Ethernet-TCP/IP network in industry has led to the growing interest in its reliability in real-time applications such as automated manufacturing systems and process control systems. However, stochastic behavior of its medium access scheme makes it inadequate for time-critical applications. In order to guarantee hard real-time communication service in Ethernet-TCP/IP network, we proposed an algorithm running over TCP/IP protocol stack without modification of protocols. In this paper, we consider communication services guaranteeing deadlines of periodic real-time messages over MAC protocols that have unbounded medium access time. We propose a centralized token scheduling scheme for multiple access networks. The token is used to allow a station to transmit its message during the time amount that is appended to the token. The real-time performance of the proposed algorithm has been described.

• Proceedings of the IEEK Conference
• /
• 2000.11a
• /
• pp.9-12
• /
• 2000

Today, QoS is one of the most critical issues in the network research area and Differentiated Services (DiffServ) is considered as the most prominent solution to provide some kinds of service differentiation without introducing any scalability problem. Among DiffServ's approaches, Assured Service (AS) provides some minimal level of QoS guarantee by treating more preferably than traditional Best Effort (BE) traffic and by using different level of drop probabilities within the same AS classes. In this paper, we investigate the ECN's capability of improving overall goodput of the flows and the possibility of resolving the fairness problem among the flows belonging to same class in Differentiated Services architecture.

• International journal of advanced smart convergence
• /
• v.3 no.2
• /
• pp.18-21
• /
• 2014

A control application requirements currently used is very low, such as packet loss rate, minimum delay on sensor networks with quality of service (QoS) requirements some packet delivery guarantee. This paper is the sampling period at the end of the actuator and sensor data transfer related to the Miss ratio for each source sensor node, use the controller and the internal ANFIS. The proposed scheme has the advantages of simplicity, scalability, and General. Simulation results of the proposed scheme can provide QoS support in WSANs.

• Journal of the Korea Society of Computer and Information
• /
• v.3 no.1
• /
• pp.125-148
• /
• 1998

The use of shaping mechanism, realized by means of a leaky bucket based algorithm on input traffic of an ATM network allows to achieve higher utilization of network resources, and to guarantee the quality of service requested by the users. The functionalities of the shaping mechanism based on leaky bucket, are characterized by the token pool sire and by input queue size. In this paper we have analyzed, using simulations, the effect on the quality of service in ATM network of leaky bucket algorithm when shaper parameters described above are changed.

• Journal of Korean Library and Information Science Society
• /
• v.25
• /
• pp.501-527
• /
• 1996

This study attempts to provide the foundation that KINITI and industrial su n.0, pporting organizations can be strong information analysis centers if they fortify their information analysis activities. The following conclusions are resulted from the analysis in the state-of-the-art-report covered in national information flow system, service methods and their publications of the information analysis activities provided by the KINITI and industrial su n.0, pporting organizations. First, the KINITI and industrial su n.0, pporting organizations have not be acquiring enough information materials. The services for bibliographic information should guarantee the uses of original documents. Second, the number of organizations providing on-line information services has been increasing, but the provided materials are not sufficiently suited for user's requests. Third, the speedy information provision and efficient information dissemination for the end users in the long distance may be possible through on-line service, but it requires information analysis procedure to select the necessary information in our industrial environment. Forth, the information activities provided by the libraries of industrial su n.0, pporting organizations should be fortified.