• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.4
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• pp.1-14
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• 2020

Recently, M/G/1 priority queues with a finite buffer for high-priority customers and an infinite buffer for low-priority customers have applied to the analysis of communication systems with two heterogeneous traffics : delay-sensitive traffic and loss-sensitive traffic. However, these studies are limited to M/G/1 priority queues with finite and infinite buffers under a work-conserving priority discipline such as the nonpreemptive or preemptive resume priority discipline. In many situations, if a service is preempted, then the preempted service should be completely repeated when the server is available for it. This study extends the previous studies to M/G/1 priority queues with finite and infinite buffers under the preemptive repeat-different and preemptive repeat-identical priority disciplines. We derive the loss probability of high-priority customers and the waiting time distributions of high- and low-priority customers. In order to do this, we utilize the delay cycle analysis of finite-buffer M/G/1/K queues, which has been recently developed for the analysis of M/G/1 priority queues with finite and infinite buffers, and combine it with the analysis of the service time structure of a low-priority customer for the preemptive-repeat and preemptive-identical priority disciplines. We also present numerical examples to explore the impact of the size of the finite buffer and the arrival rates and service distributions of both classes on the system performance for various preemptive priority disciplines.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.9
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• pp.1320-1329
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• 2022

Currently, advanced national research network groups are continuously conducting R&D for the requirement to provide SDN/NFV-based network automation and intelligence technology for R&E users. In addition, the requirement for providing large-scale data transmission with the high performance networking facility, compared to general network environments, is gradually increasing in the advanced national research networks. Accordingly, in this paper, we propose an open API-based virtual network provisioning automation platform for large data transmission researched and developed to respond to the networking requirements of the national research network and present the implementation results. The platform includes the KREONET-S VDN system that provides SDN-based network virtualization technology, and the Kubernetes system that provides container-oriented server virtualization technology, and the Globus Online, a high-performance data transmission system. In this paper, the environment configurations, the system implemetation results for the interworking between the heterogeneous systems, and the automated virtual network provisioning implementation results are presented.

• Journal of KIISE:Information Networking
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• v.34 no.5
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• pp.405-422
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• 2007

Recently, according to the network environment, there are many researches for home network. Nowadays, in home network, the method that access control policy is managed for each home device by using ACL is popular, and EAM (Extranet access management) is applied as a solution. In addition, the research about secure OS is ongoing based on open operating system and the research of user authentication mechanisms for home network using home server is also in progress. However, these researches have some problems as follows; First, the transmission scope of expected access technology in home network is wide, so unauthenticated outside terminal can access the home network. Second, user is inconvenient because user need to set the necessary information for each device. Third, user privacy and convenience are not considered. OSGi provides a service platform for heterogeneous technologies in home network environment. Here, user access control is one of the core parts which should have no problems such as above items, but there are no concrete researches yet. Thus in this paper, we propose an access control policy management framework and access control operation based on RBAC for user access control in home network environment in which OSGi service platform is operated. First, we list the consideration which is not clearly mentioned in OSGi standard, and then we solve these above problems through new framework. In addition, we propose the effective and economical operation method which reduces the policy change frequency for user access control by using RBAC concept though limited resource of home gateway. Besides, in this paper, these proposed policies are defined separately as user-role assignment policy and permission-role assignment policy, and user decide their own policies. In conclusion, we provide the scheme to enhance the user convenience and to solve the privacy problem.

• Journal of Korea Spatial Information System Society
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• v.1 no.2 s.2
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• pp.21-31
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• 1999

In accordance with the completion of the spatial database building works in the central and/or local government authorities as well as the rapid popularization of various information services through internet, it is heavily required to provide spatial information services through World Wide Web. To provide a qualified spatial information service, it is crucial to have a Web-based GIS (Geographic Information Service) service system equipped with the publicity, the convenient accessibility, and the easy-to-use user interface. In this paper, we introduce a new component system for Web-based spatial information services based on the OpenGIS Simple Feature specification for OLE/COM[3] and OLE DB specification[4]. The important functionality of a Web-based spatial information service system includes its accessibility of various existing GIS server system and huge databases in addition to the resolution of response-time delay problems caused by transmitting a large amount of digital maps via internet[6]. To cope with these problems, our component system has been designed to access heterogeneous databases in transparent manner and to support vector-based and/or image-based image production techniques for shortening transmission time.

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.83-94
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• 2004

Recent researches which purport to Integrate distributed information have been concentrated on developing efficient mediator systems that not only provide a high degree of autonomy for local users but also support the flexible integration of required functions for global users. However, there has been little attention on how to evaluate a global query in a mediator. A global query is transformed into a set of its sub-queries and each sub-query is the unit of evaluation in a remote server. Therefore, it is possible to speed up the execution of a global query if the previous results of frequently evaluated sub-queries are materialized in a mediator. Since the Integration schema of a mediator can be incrementally modified and the evaluation frequency of a global query can also be continuously varied, query usage should be carefully monitored to determine the optimized set of materialized sub-queries. Furthermore, as the number of sub-queries increases, the optimization process itself may take too long, so that the optimized set Identified by a long optimization process nay become obsolete due to the recent change of query usage. This paper proposes the adaptive selection of materialized sub-queries such that available storage in a mediator can be highly utilized at any time. In order to differentiate the recent usage of a query from the past, the accumulated usage frequency of a query decays as time goes by.

• Journal of Korea Multimedia Society
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• v.3 no.5
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• pp.479-494
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• 2000

Although the proliferation of real-time multimedia services over the Internet might indicate its successfulness in dealing with heterogeneous environments, it is obvious, on the other hand, that the internet now has to cope with a flood of multimedia data which consumes most of network communication channels due to a great deal of video or audio streams. Therefore, for the purpose of an efficient and appropriate utilization of network resources, it requires to develop and deploy a new scalable transmission technique n consideration of respective network environment and individual clients computing power. Also, we can eliminate the waste effects of storage device and data transmission overhead in that the same video stream duplicated according to QoS. The purpose of this paper is to develop a technology that can adjust the amount of data transmitted as an MPEG video stream according to its given communication bandwidth, and technique that can reflect dynamic bandwidth while playing a video stream. For this purpose, we introduce a media scalable media decomposer working on server side, and a scalable media composer working o n a client side, and then propose a scalable transmission method and a media sender and a media receiver in consideration of dynamic QoS. Those methods proposed her can facilitate an effective use of network resources, and provide multimedia MPEG video services in real-time with respect to individual client computing environment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.12
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• pp.17-27
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• 2011

Most of the previous mobility management protocols such as IETF MIPv4/6 and its variants standardized by the IETF do not support global seamless handover because they require partially changes of the existing network infrastructure. In this article, we propose a simple mobility management protocol (SMMP) which can support global seamless handover between homogeneous or heterogeneous wireless networks. To do this, the SMMP employs separate location management function as DMMS to support global user and service mobility and the bidirectional tunnels are dynamically constructed to support seamless IP mobility by using the IEEE MIH extension server, which is extended the IEEE 802.21 MIH standards. The detailed architecture and functions of the SMMP have been designed. Finally, the mathematical analysis and the simulation have been done. The performance results show the proposed SMMP outperforms the existing MIPv6 and HMIPv6 in terms of handover latency, packet loss, pear signal noise ratio (PSNR).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.46-54
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• 2018

The Internet of Things (IoT) is an environment in which various devices provide services to users through communications. Because of the nature of the IoT, data are stored and distributed in heterogeneous information systems. In this situation, IoT end applications should be able to access data without having information on where the data are or what the type of storage is. This mechanism is called Service Discovery (SD). However, some problems arise, since the current SD architectures search for data in physical devices. First, turnaround time increases from searching for services based on physical location. Second, there is a need for a data structure to manage devices and services separately. These increase the administrator's service configuration complexity. As a result, the device-oriented SD structure is not suitable to the IoT. Therefore, we propose an SD structure called Name-based Service-centric Service Discovery (NSSD). NSSD provides name-based centralized SD and uses the IoT edge gateway as a cache server to speed up service discovery. Simulation results show that NSSD provides about twice the improvement in average turnaround time, compared to existing domain name system and distributed hash table SD architectures.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.6
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• pp.602-613
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• 2001

Recently, the computing has developing in distributed object computing environment for supporting a programming paradigm of distributed application requiring interoperability between heterogeneous clients and servers. It involves the complex networking and the object-oriented technologies for various multimedia application service. In this paper, we construct the real-time object group platform for solving the difficulties of managements of distributed objects and the real-time constraints by requiring for real-time service supporting of applications in distributed computing environment. The existing researches are being tried to only improving the performance of systems by using real-time CORBA itself, or modifying the part of CORBA compliance. Hence, we design a new model of real-time object group platform that can support the real-time requirement without modifying the ORB. The structure of our real-time object group analyzed and defined the requirement about object management and real-time application service sides. And the role of the components of real-time object group is divided into 2 classes for reducing the side effect of interoperability between management and service. Also, we considered how to transparently express the parameters of real-time properties for clients and developers of server's service objects. If the expression of real-time parameters is transparent, then the developer can easily extend the real-time parameters simply and flexibly. Therefore, in this paper we defined the role of components of platform and described functions of each component and designed and then implemented the real-time object group platform. Finally, we showed the execution procedures of implemented our platform for verifying the functionality.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.931-942
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• 2010

A home network provides users with a variety of information services. The kind and quality of the services can be substantially enhanced by utilizing a variety of data from sensors. However, home networks currently limit their potential by focusing on providing multimedia services rather than services utilizing sensor data. Outdoor electronics are frequently made in a form that emphasizes only certain limited functions in contrast to home appliances. Thus, sensors with one or two functions rather than many can be used in outdoor systems and their use will be more economical than using sensor nodes indoors with more complex home appliances. In this study, we chose to work with motion sensors as they have many potential uses, and we selected a parking lot control system with to use the motion sensors. This parking lot control system was implemented and applied as part of a home network. For this purpose, we defined and implemented a protocol to manage the network in a ubiquitous sensor network environment for the wireless home network in this study. Although a network management system in a Ubiquitous Sensor Network (USN) related to this study is being advanced for other projects, the protocol interface and message system have not yet been clearly defined for use in a general purpose network or in an extension into heterogeneous kinds of networks, communication support, etc. Therefore, USN network management should be conducted for management of faults, composition, power, and applications. To verify the performance of the protocol interface designed in this study, we designed and implemented the necessary units (sensor nodes, sensor gateway, and server) for each network section and, with them, proved the validity of this study.