• Journal of KIISE:Information Networking
• /
• v.33 no.3
• /
• pp.277-287
• /
• 2006

Most of the existing broadband access networks based on DSL, cable modem, and Ethernet support the best-effort internet access service, and adopt the flat rate pricing mechanism. It is almost impossible to provide the differentiated communication services, in current broadband access networks, for the different users and/or the different application services. Currently, however, the advances in multimedia, communication, and security technologies push the interactive and/or streaming multimedia services and VPN services to be widely deployed over Internet, and they require more QoS-sensitive services than the best-effort service. Though various QoS technologies such as RSVP-based IntServ and DiffSern were already developed and under standardization in Internet world, it is impractical to replace the existing QoS-unaware access networks with the QoS-enabled ones at a time to deploy QoS-sensitive services. In this paper, after analyzing current broadband access network architectures and the status of QoS support, we propose a practical approach to support multimedia QoS in the broadband access networks. The approach will be based on the integration of the differentiated pricing and the DiffServ technology. And it will be a step-wise approach to support backward compatibility with the legacy broadband access networks as much as possible.

• Journal of KIISE:Computing Practices and Letters
• /
• v.10 no.6
• /
• pp.460-471
• /
• 2004

Since the RTP is suitable for real-time data transmission in multimedia services like VoD, AoD, and VoIP, it has been adopted as a real-time transport protocol by RTSP, H.323, and SIP. Even though the RTP protocol stack for embedded systems has been in great need for efficient support of multimedia services, such a stack has not been developed yet. In this paper, we explain embeddedRTP which supports the RTP protocol stack at the kernel level so that it is suitable for embedded systems. Since embeddedRTP is designed to reside in the UBP module, existing applications which rely ell TCP/IP services can proceed the same as before, while applications which rely on the RTP protocol stack can request HTP services through embeddedRTp API. EmbeddedRTP stores transmitted RTP packets into per session packet buffer, using the packet's port number and multimedia session information. Communications between applications and embeddedRTP is performed through system calls and signal mechanisms. Additionally, embeddedRTP API makes it possible to develop applications more conveniently. Our performance test shows that packet-processing speed of embeddedRTP is about 7.5 times faster than that oi VCL RTP for multimedia streaming services on PDA in spite that its object code size is reduced about by 58% with respect to UCL RTP's.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.49 no.9
• /
• pp.18-26
• /
• 2012

As the performance of the next-generation broadband wireless networks is dramatically enhanced, various services (i.e., education, video conferencing, online games, etc.) have been provided to users through a smart mobile platform. Since those services are usually provided by using the centralized architecture, it is difficult for a lot of users to provide the scalable communication service with regard to traffic management. To solve these problems, we have proposed an architecture of P2P-based group communication management scheme using smart mobile device. More specifically, we design the group management protocol and algorithm for the group member management and the traffic management. By using these methods, the mobile multimedia streaming service can be provided with scalability. In order to verify the performance of the proposed scheme, we have mathematically analyzed the performance in terms of the average transmission delay and bandwidth utilization.

• Journal of Korea Multimedia Society
• /
• v.12 no.9
• /
• pp.1201-1209
• /
• 2009

Recently, the convergence of the telecommunications industry through the development of network media has brought along interactive data services in addition to the traditional broadcast services by providing direct connections between the users and the broadcasters. This can be easily achieved by the combination of existing network technology and multimedia technology, but in reality, as seen in the actual implementation of IPVT, it's difficult to provide satisfactory levels of service to users due to issues of network bandwidth and problems of streaming system. In particular, a network which is able to fully support Qos/QoE, and also a fast enough channel changing technology that is satisfactory to the user, are prerequisites for IPTV success. Therefore this thesis proposes a fast channel changing technique to delivery enhanced IPTV user experience. Recent IP set-top-boxes use only a small portion of the CPU to feed Ethernet packets to the hardware decoder and play them. Thus, by making IP set-top-boxes share cached channel information and content with each other, reducing the load on the server and enhancing the channel changing time is made possible.

• Journal of Internet Computing and Services
• /
• v.21 no.1
• /
• pp.1-15
• /
• 2020

This study explores reasonable alternatives to internet interconnection policy. Due to the development of information and communication technology, patterns of the Internet usage are changing rapidly, including increase of video streaming services. For this reason, there is a lively discussion of the Internet interconnection policy, which integrates various Internet service operators into one ecosystem. We conducted an Analytic Hierarchy Process(AHP) analysis with 16 experts in government/public, and academic sectors, and alternative selection criteria and their corresponding alternatives and detailed tasks were evaluated. According to the results, the most important alternative selection criteria was a "fair charge against foreign service operators", and the most desirable alternative was "partial revise". Moreover, the experts responded that "reassessment of the principle of the charge" is the most urgent task to improve the Internet interconnection policy.

• Journal of Digital Contents Society
• /
• v.19 no.8
• /
• pp.1545-1554
• /
• 2018

In order to support the mobility of the wireless devices, at least two APs (Access Points) must be arranged in a single AP area to maintain communication area. In the WLAN (Wireless LAN) environment, seamless handover is one of the most important issues in terms of effective utilization of wireless networks and maximization of services for users. On the other hand, SDN (Software-Defined Networking), which is emerging rapidly in recent years, is revolutionizing network management in terms of flexibility, fine control, and convenience. SDN originally reduces latency time or increases network robustness by real-time flow table control reducing or bypassing paths between switches in LAN-based data centers. In this study, we apply OpenFlow, a SDN platform focused on wired LAN, to a dense WLAN environment using legacy APs to implement and evaluate seamless handover for streaming services of digital contents.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.44 no.2
• /
• pp.255-272
• /
• 2020

This exploratory study investigated Chinese consumers' perceived usefulness and risks of fashion apps and identified reasons for continuance and discontinuance intentions. This study conducted focus group interviews with a convenience sample of 13 Chinese students majoring in fashion in Korea. Based on interviewee responses, this study identified five attributes leading the perceived usefulness of mobile fashion apps (ubiquity and convenience, multi-media information, personalization, interactivity between consumers, and immediateness) and sub elements related to the five attributes. Five types of perceived risk (privacy risk, security risk, product risk, loss of future opportunity, and time risk) were identified in relation to Chinese consumers' use of fashion apps. The important role of live streaming services was uniquely identified by Chinese fashion app users. Usefulness of location-based information provided by mobile fashion apps were differently perceived according to respondents' use purpose, and augmented reality services provided by the apps were related to entertainment rather than usefulness. This study provides meaningful insights into Chinese consumers' perceptions of fashion apps and important app attributes that influence their continuance and discontinuance intentions. The findings from this study lend preliminary implications for future researchers and fashion businesses interested in the Chinese app market.

• KIPS Transactions on Computer and Communication Systems
• /
• v.4 no.4
• /
• pp.141-146
• /
• 2015

Data have been increased enormously due to the development of IT technology such as recent smart equipments, social network services and streaming services. To meet these environments the technologies that can treat mass data have received attention, and the typical one is Hadoop. Hadoop is on the basis of open source, and it has been designed to be used at general purpose computers on the basis of Linux. To initial Hadoop nearly no security was introduced, but as the number of users increased data that need security increased and there appeared new version that introduced Kerberos and Token system in 2009. But in this method there was a problem that only one secret key can be used and access permission to blocks cannot be authenticated to each user, and there were weak points that replay attack and spoofing attack were possible. Hence, to supplement these weak points and to maintain efficiency a protocol on the basis of group key, in which users are authenticated in logical group and then this is reflected to token, is proposed in this paper. The result shows that it has solved the weak points and there is no big overhead in terms of efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.4B
• /
• pp.659-669
• /
• 2010

The P2P IPTV will create a new paradigm for the Internet services. However, it cannot guarantee the reliability of their server and QoS because of using common Internet users(peers) for SIP server or relay server, though the infrastructural cost is low. This paper proposes the ISP-based P2P IPTV architecture which can solute the limitations of conventional P2P-based IPTV. In this model, ISP can build P2P overlay network with ISP servers and directly manage each server needed for session connection. So, the servers have higher performance and better reliability than previous one. Besides, robustness is improved because each sever is set by P2P overlay network. To evaluate the characteristics of the ISP-based P2P IPTV architecture, we simulate it for some parameters which are end-to-end streaming delay time, connection delay time and traffic amount. We compared the proposed architecture with the conventional P2P architecture about video service and confirmed that the performance of ISP-based P2P IPTV is better than conventional P2P based IPTV.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.10B
• /
• pp.919-928
• /
• 2006

A periodic broadcasting is known as an efficient technique for delivering popular videos to reduce bandwidth requirements for transmitting streaming video to viewers in video-on-demand (VoD) services. However, the most periodic VoD schemes approach needs frequency channel hopping, many segments of video managing, and using many channel at the same time. These make it difficult to implement. In this paper, we propose a Staircase Staggered broadcasting scheme which has a simple structure and substantially improved VoD efficiency. The numerical results demonstrate that the viewer's waiting time of the Staircase Staggered broadcasting scheme is close to the staircase broadcasting scheme and the maximum buffer requirements of this can be adapted for demanding rate by adjusting the short front part of a video sizes.