• KIPS Transactions on Computer and Communication Systems
• /
• v.1 no.3
• /
• pp.205-218
• /
• 2012

Mobility management of the mobile nodes and provision of seamless handover is crucial to an efficient support for the global roaming of the mobile nodes in next-generation wireless networks. Mobile IPv6 and mobility management in extended IP layer, which highly depend on traffic characteristics and user mobility models, were proposed by the IETF. Therefore, to evaluate the in-depth performance about these factors is important. Generally, the performance of IPv6-based mobility management protocol is evaluated through simulation. This paper shows the correlation between network parameters and performance metrics through numerical results, which is investigated how influence handoff latency and packet loss. And this paper uses mathematical analysis of the system parameters, such as the subnet residence time, the packet arrival rate and delay in wireless connection through the analytical framework which evaluate the performance of IPv6-based mobility management protocol.

• KIPS Transactions on Computer and Communication Systems
• /
• v.1 no.1
• /
• pp.29-34
• /
• 2012

Wireless multicast service can be used for video streaming service to save the network resources by sending the same popular multimedia contents to a group of users at once. For better multimedia streaming multicast service, we propose a quality-aware rate adaptation (QARA) scheme for scalable video multicast in rate adaptive wireless networks. In QARA, transmission rate is determined depending on the content's type and users' channel conditions. First, the base layer is transmitted by a low rate for high reliability. That means we provide basic service quality to all users. On the contrary, the transmission rate for enhancement layer is adapted by using channel condition feedback from a randomly selected node. So, the enhancement layer frames in a multimedia content is sent with various transmission rates. Therefore, each node can be provided with differentiated quality services. Consequently, QARA is capable of serving heterogeneous population of mobile nodes. Moreover, it can utilize network resources more efficiently. Our simulation results show that QARA outperforms utilization of the available transmission rate and reduces the data transmission time.

• The KIPS Transactions:PartC
• /
• v.17C no.3
• /
• pp.271-280
• /
• 2010

For the next generation mobile communication system, diverse wireless network techniques such as beyond 3G LTE, WiMAX/WiBro, and next generation WLAN etc. are proceeding to the form integrated into the All-IP core network. According to this development, Beyond 3G integrated into heterogeneous wireless access technologies must support the vertical handover and network to be used of several radio networks. However, unified management of each network is demanded since it is individually serviced. Therefore, in order to solve this problem this study is introducing the theory of Common Radio Resource Management (CRRM) based on Generic Link Layer (GLL). This study designs the structure and functions to support the vertical handover and propose the vertical handover algorithm of which policy-based and MCDM are composed between LTE and WLAN systems using GLL. Finally, simulation results are presented to show the improved performance over the data throughput, handover success rate, the system service cost and handover attempt number.

• Journal of KIISE:Computing Practices and Letters
• /
• v.14 no.1
• /
• pp.13-21
• /
• 2008

In general, data communication among sensor nodes requires more energy than internal processing or sensing activities. In this paper, we propose a noble technique to reduce the number of packet transmissions necessary for sending/receiving queries/results among neighboring nodes with the help of context-aware routing tables. The important information maintained in the context-aware routing table is which physical properties can be measured by descendent nodes reachable from the current node. Based on the information, the node is able to eliminate unnecessary packet transmission by filtering out the child nodes for query dissemination or result relaying. The simulation results show that up to 80% of performance gains can be achieved with our technique.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.12
• /
• pp.2996-3009
• /
• 1997

A lot of talks on the Quality of services (QoS) so far were limited only either for the network itself or for the end system, But, recently it is becoming more important to have the seamless end-to-end QoS support to meet the networked multimedia service requirements This paper proposes the QoS based resource management architecture which supports the large scale distributed systems under heterogeneous environment. The architecture introduces a couple of key concepts such as abstractions and algorithms. Abstractions capture the three perspectivest found in all systems: application, resource, and system, on the ofter hand algorithms manage system resources based on information in the three abstractions. We also explain the on-line resource management flow as well as the benefit function which specifies the level of benefit accrued to the application user as a function of the level of service provided by the system. At the end of the paper, the QoS based resource management applied to the tele-seminar application is described to show its practical utilization.

• The KIPS Transactions:PartC
• /
• v.16C no.2
• /
• pp.275-284
• /
• 2009

Fast development of network technology and digitalization of various kinds of information are accelerating the convergence of between them. Accordingly, an environment for integrated service is needed, where users can be provided with various kinds of information such as voice, video, and text, using even different kinds of devices in heterogeneous networks for communication and broadcasting. In general, enablers integrate several functions to provide with various services in application layer based on IMS in BcN including even different kinds of networks. But in order to receiving convergence services, we must reason the environment of the user through the profiles of the networks and the devices and provide a suitable service to the user. In this paper, we will propose an efficient architecture and functions of a context-aware module which decides the appropriate services based on the profiles in the IMS enabler and its convergence service environments.

• Journal of KIISE:Information Networking
• /
• v.36 no.4
• /
• pp.275-285
• /
• 2009

RFID technology using the smart tag technology as a part of the sensor network is currently in the spotlight. But there are still many problems in applying the technology in a ubiquitous environment, induding at the point when anybody can read the tag information and the authentication between the tag and the reader, and security problems in very low-cost smart tag implementation. The proposed scheme is designed to enhance security and efficiency related to various services required in RF networks, based on the reliable peripheral devices for users of passive RFID tag. Using passive RFID tag, which has been applied to authentication transactions in existing papers, this study also proposed an appropriate management scheme that is suitable for a dynamic environment and setting a temporary group to provide various services. also proposed scheme is support RFID grouping, temporary group of service and security servicce, improved efficiency of communication.

• Journal of the Korea Society of Computer and Information
• /
• v.26 no.1
• /
• pp.57-67
• /
• 2021

Recently, multi-modal deep learning techniques that combine heterogeneous data for deep learning analysis have been utilized a lot. In particular, studies on the synthesis of Text to Image that automatically generate images from text are being actively conducted. Deep learning for image synthesis requires a vast amount of data consisting of pairs of images and text describing the image. Therefore, various data augmentation techniques have been devised to generate a large amount of data from small data. A number of text augmentation techniques based on synonym replacement have been proposed so far. However, these techniques have a common limitation in that there is a possibility of generating a incorrect text from the content of an image when replacing the synonym for a noun word. In this study, we propose a text augmentation method to replace words using word hierarchy information for noun words. Additionally, we performed experiments using MSCOCO data in order to evaluate the performance of the proposed methodology.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.2
• /
• pp.425-438
• /
• 1999

In recent days network computing technologies have bee developed rapidly and the extended use of Internet applications for enterprises such as internet/extarnet in and between enterprises has been increased enormously. Therefore the business in the future will be executed by virtual enterprise. Virtual enterprises which is based on information sharing between enterprises are composed of work processes related to information exchange between virtual enterprises, the team members who are representatives of the organizations that are participated in the actual business of virtual enterprises, and members who are representatives of the organizations that are participated in the actual business of virtual enterprises, and environment that are provided by supporting CALS(continuous Acquisition and Life cycle Support or commerce At light Speed). Supporting system of IDE(Integrated Data Environment)for CALS implementation that is provided as an environment of virtual enterprises has to ensure the autonomies of local data and to provide the accessibility of heterogeneous database of enterprises on network transparently for giving user a single global view of data. This paper introduce the design and implementation of the database broker system that can be accessed data transparently by the suers of participated enterprises in the integrated data environment supporting virtual enterprises. The system uses java/CORBA technology in Web environment and Object Query language (OQL) to process the queries of relational database system, object-oriented database system, and file information.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37C no.11
• /
• pp.1138-1147
• /
• 2012

In this paper, an efficient power control based MF-TDMA resource allocation scheme is proposed for next generation military satellite communication systems. The proposed scheme has the flexibility is used to support heterogeneous terminals with differ in transmission capabilities. The method can be divided into two parts : burst size calculation and burst structure determination. At first, we estimate the link budget taken into account a dynamic satellite link state variation. Then, applicable ACM level and burst size is chosen. In burst structure determination phase, we reorganize the burst structure in time-frequency domain by controlling limited power, bandwidth, time resources. In particular, we compensate the power spectral density among different terminals to integrate them in same transponder, Furthermore, we increase the packing efficiency by controlling the ACM level of the burst in applicable power spectral density range. Simulation results show that the method increase the spectral efficiency and burst packing efficiency. In addition, slot allocation rejection ratio is successfully reduced.