• International Journal of Internet, Broadcasting and Communication
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• v.8 no.1
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• pp.53-63
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• 2016

This paper applies WiMedia UWB network into a wireless ship area network (WSAN) so as to support high-quality multimedia services on board and reliable instrument control information as well, since the need for mixed high-quality video traffic and shipboard control data traffic is essential for a high-cost valued digital ship. Thus, in this paper, prioritized contention access (PCA) and distributed reservation protocol (DRP) based on WiMedia UWB (ECMA-368) MAC protocols are combined and proposed to such mixed traffic environment, by varying the portions of superframe according to traffic type. It is shown that the proposed WiMedia UWB MAC protocol can provide reliable mixed video and shipboard control data traffic as well.

• Journal of Communications and Networks
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• v.15 no.6
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• pp.614-634
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• 2013

The proliferation of real-time multimedia services requires huge amounts of data transactions demanding strict quality-of-service (QoS) guarantees. Multicast transmission is a promising technique because of its efficient network resource utilization. However, high head-of-line (HOL) blocking probability and lack of service-specific QoS control should be addressed for practical implementations of multicast networks. In this paper, a topology aware fanout set division (TAFD) scheme is proposed to resolve these problems. The proposed scheme is composed of two techniques that reduce HOL blocking probability and expedite packet delivery for large-delay branches regarding multicast tree topology. Since management of global topology information is not necessary, scalability of the proposed scheme is guaranteed. Mathematical analysis investigates effects of the proposed scheme and derives optimal operational parameters. The evaluation results show that the TAFD scheme achieves significant delay reduction and satisfies required delay bounds on various multicast networks.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.11a
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• pp.139-144
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• 2003

Mobile Node has to maintain communication as they move form place to place, so it doesn't guarantee Quality of Service(QoS). Fast Handoff is important to provide multimedia and real-time applications services in mobile, and it is closely related to handoff delay. Therefore, handoff delay problem is actively studied to quarantee QoS as a main issue in mobile IP research area. Next generation Mobile IPv6 resolve this problem somewhat, triangle problem for first packet and handoff delay still remain. In this paper, we suggest SNMP Information-based routing that adds keyword management method to Information-based routing in active network in order to resolve such a problem, and then suggest QoS controlled handoff based on SNMP Information-Based routing. After modeling of suggested method and existing handoff method, simulations are carried out with NS-2 for performance evaluation. The results of simulations show the some improvement on handoff delay, and therefore on QoS improvement.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.5
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• pp.203-216
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• 2004

Recent advances in video coding technology have resulted in rapid growth of application in mobile communication, With this explosive growth reliable transmission and error resilient technique become increasingly necessary to offer high quality multimedia service. In this paper, we present the result of our investigation on the error resilient performance evaluation of the MPEG-4 simple profile under the H.324/M and the H.264/AVC baseline under the IP packet networks. Especially, we have tested error resilient tools of MPEG-4 simple profile such as resynchronization marker insertion, data partitioning, and of H.264/AVC baseline such as the flexible macroblock ordering (FMO) scheme. The objective quality of decoded video is measured in terms of rate and PSNR under various random bit and burst error conditions.

• Journal of Korea Multimedia Society
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• v.12 no.11
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• pp.1530-1538
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• 2009

KISTI-ACOMS ver. 2.0 has been distributed to more than 340 academic societies and used by more than 130 academic societies for 4 years since 2005 and still is desired for use by lots of other academic societies. But contrary to the desire and requests for system upgrades of academic societies, ACOMS has not been improved for last 3 years and some academic societies began to use domestic or foreign similar pay online peer review systems. In this paper, a new integrated portal service system is suggested in order to attempt national production cost-saving and quality improvement of academic information by creating and collecting high quality scientific and technologic academic information inexpensively. We come up with methodology of integration and utilization of a personal academic activity portal system interoperable with other services of KISTI, an open citation reference database automatically constructed by authors' activity and a journal evaluation system based on impact factor.

• Journal of Korea Multimedia Society
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• v.16 no.10
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• pp.1171-1179
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• 2013

Interactive audio service provide with audio generating and editing functionality according to user's preference. A spatial audio object coding (SAOC) scheme is audio coding technology that can support the interactive audio service with relatively low bit-rate. However, when the SAOC scheme remove the specific one object such as vocal object signal for Karaoke mode, the scheme support poor quality because the removed vocal object remain in the SAOC-decoded background music. Thus, we propose a new SAOC vocal harmonic extranction and elimination technique to improve the background music quality in the Karaoke service. Namely, utilizing the harmonic information of the vocal object, we removed the harmonics of the vocal object remaining in the background music. As harmonic parameters, we utilize the pitch, MVF(maximum voiced frequency), and harmonic amplitude. To evaluate the performance of the proposed scheme, we perform the objective and subjective evaluation. As our experimental results, we can confirm that the background music quality is improved by the proposed scheme comparing with the SAOC scheme.

• Journal of Computing Science and Engineering
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• v.7 no.3
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• pp.168-176
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• 2013

Long-term evolution (LTE) is emerging as a major candidate for 4G cellular networks to satisfy the increasing demands for mobile broadband services, particularly multimedia delivery. Multiple-input multiple-output (MIMO) technology combined with orthogonal frequency division multiple access and more efficient modulation/coding schemes (MCS) are key physical layer technologies in LTE networks. However, in order to fully utilize the benefits of the advances in physical layer technologies, the MIMO configuration and MCS need to be dynamically adjusted to derive the promised gains of 4G at the application level. This paper provides a performance evaluation of video traffic with variations in the physical layer transmission parameters to suit the varying channel conditions. A quantitative analysis is provided using the perceived video quality as a video quality measure (evaluated using no-reference blocking and blurring metrics), as well as transmission delay. Experiments are performed to measure the performance with changes in modulation and code rates in poor and good channel conditions. We discuss how an adaptive scheme can optimize the performance over a varying channel.

• Journal of KIISE:Information Networking
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• v.37 no.2
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• pp.122-134
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• 2010

With the rapidly increasing demand of traffic applications, the need to support seamless and robust multimedia services in the Vehicular Ad hoc Network is growing. Fast handover for the MIPv6 (FMIPv6) developed to solve the MIPv6's problem as well as Mobile IPv6 (MIPv6) for basic mobility protocol have been developed to support seamless handover in mobile environment. However, MIPv6 and FMIPv6 are useless for Quality-of-Service (QoS) services such as multimedia applications due to the long handover latency and the packet loss problem. In this paper, we propose a seamless and robust handover scheme that supports multimedia services in Vehicular Ad hoc Network using oCoA and background DAD. Through performance evaluation, we show that the proposed scheme is more proper for Vehicular Ad hoc Network than other schemes.

• International Journal of Quality Innovation
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• v.8 no.3
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• pp.123-155
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• 2007

This research treated the secondary school teachers as the research scale and the research targets included the following: secondary school (employ unit), center of teacher education, and qualified teachers. In terms of these three groups of people, the topics of exploration focused on the perception of suitable teachers, perception of evaluation standard during the process of teacher examination and the relationship among teacher examination systems. The research was managed by two phases: the first phase referred to literature reorganization, expert interview, the qualities and conditions of suitable teachers, important evaluation standard during the process of teacher examination and teacher examination system used; the second phase included questionnaire survey, employ school acquisition, the perception of centers of teacher education and qualified teachers toward the suitability condition and examination evaluation standard in the first phase and teacher examination system used. This research found out that as to the perception of suitable teachers, through data collection, there were six factors reorganized. The levels of their importance were as follows: education devotion, teaching capacity, class management, capacity to guide special students, capacity to communicate with the parents and the will to undertake administrative works. Noticeably, employee unit and centers of teacher education apparently valued class management more, compared with trained teachers; as to evaluation standard of examination, the analytical result found out that the perception of three groups were different in terms of the views toward educational works, written examination data, candidate's age, club experience at school and capacity to use multimedia support teaching materials. This research further proposed six suggestions for centers of teacher education and trained teachers: (l) employ schools considerably valued educational devotion; (2) trained teachers tended to neglect the importance of class management; (3) employee unit considerably cared about the new teachers' competence to use multimedia support teaching materials; however, trained teachers did not have the same view; (4) employee unit considerably cared about new teachers' views toward educational works as well as the candidates' ages; (5) generally speaking, trained teachers neglected the importance of club experience at school; (6) the data revealed that written examination data was not relatively important in terms of teacher examination.

• Journal of KIISE:Information Networking
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• v.36 no.4
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• pp.360-368
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• 2009

Recently, broadband access networks have been competitively deployed all over the world with the development of various multimedia services for such a network. ETRI(Electronics and Telecommunications Research Institute) built the FTTH(Fiber-To-the-Home) service center to develop a next-generation equipment and a high-quality service/platform as well as to promote domestic industry in the field of optical communication. The FTTH service center has a variety of test equipments such as FTTH standard testbed for a BMT(bench mark test), a network operation center, and IPTV service equipments. Also, ETRI deployed a new type of commercial optical access networks cooperating with ISP(Internet Service Provider). This paper presents the performance evaluation of FTTH E-PON(Ethernet Passive Optical Network) system as a platform for TPS(Triple Play Service) based on QoS(Quality of Service) and QoE(Quality of Expericence) issues. This FTTH E-PON system is successfully demonstrated as an optical access network system by commercial network service provider and the FTTH service center of ETRI.