• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.299-306
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• 2010

IPTV and VoIP services are considered as killer applications over Mobile WiMAX network, which provideshigh mobility and data rate. Among those which affect the quality of voice in those services, the jitter buffer or playout buffer can compensate the poor voice quality caused by the packet drop due to frequent route change or differences among routes between service endpoints. In this paper, we analyze the correlation between the sleep interval length and jitter buffer size in order to guarantee a predefined level of voice quality. For this purpose, we present an end-to-end delay model considering additional delay incurred by the WiMAX PSC-II sleep mode and a VoIP service quality requirement based on the delay constraints. Through extensive simulation experiments, we also show that the increase of jitter buffer size may degrade the voice quality since it can introduce additional packet drop in the jitter buffer under WiMAX power saving mode.

• The Journal of the Korea Contents Association
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• v.7 no.1
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• pp.103-115
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• 2007

The vulnerability issue on IEEE 802.1x wireless LAN has been permits the malicious attack such as Auth/Deauth flooding more serious rather than we expected. Attacker can generate huge volume of malicious traffic as the same methods on existing wired network. The objective of wireless IP Traceback is to determine the real attack sources, as well as the full path taken by the wireless attack packets. Existing IP Traceback methods can be categorized as proactive or reactive tracing. But, these existing schemes did not provide enhanced performance against DoS attack on wireless traffic. In this paper, we propose a 'TTL based advanced Packet Marking' mechanism for wireless IP Packet Traceback with wireless Classification function. Proposed mechanism can detect and control DoS traffic on AP and can generate marked packet for reconstructing on the real path from the non-spoofed wireless attack source, by which we can construct secure wireless network based on AP with enhance traceback performance.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.113-118
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• 2017

As interest in mobile devices and networks has increased recently, voice over internet protocol (VoIP) service, which is a technology for transmitting voice data using an existing internet protocol (IP) network, has rapidly spread, Cheap voice call service has become possible. As the digital broadcasting service becomes popular, hybrid fiber coaxial (HFC) network technology, which uses broadband cable network through fusion of broadcasting and communication, utilizes existing communication system and network equipment to provide various new services such as interactive broadcasting service. Therefore, if UGS-AD is applied to VoCM and RTPS is applied to MTA in order to guarantee the quality of voice data in actual HFC Internet service network, it is possible to smoothly perform voice data transmission in narrow upstream band which is a problem in actual commercial HFC network We also proposed a method to improve VoIP service by improving QoS of voice data in HFC Internet service network.

• Journal of Astronomy and Space Sciences
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• v.24 no.3
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• pp.219-226
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• 2007

Among the interplanetary shock (IP shock)s observed by ACE spacecraft at 1AU during 1997 to 2000, we have selected 31 IP shocks which had triggered the interplanetary type II radio bursts detected by the WIND spacecraft while those shocks were leaving the Sun. We compared the observed IP shock propagation speeds and the IP shock transit speeds estimated by time difference between the interplanetary type II radio burst detection and the IP shock observation. Then, we found that the mean acceleration of the IP shocks between the Sun and the Earth is about $-1.02m/sec^2$, which means the deceleration contrary to the positive acceleration predicted by Parker solar wind model. It is also verified that the acceleration of the IP shock does not show any linear correlation with the shock propagation speed and the Mach number of the IP shock.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.939-954
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• 2013

Korean military is developing the next generation military satellite communications system in order to achieve the requirements of future military satellite communication such as high speed, high capacity, survivability, all IP networking, and on-the-move. In this paper, we survey and analyze the research interests about optimal resource allocation and IP networking such as MF-TDMA, random access, satellite IP routing, and PEP. Conventional researches have focused on the increase in channel throughput and efficiency. In addition to these measurements, we consider heterogeneous satellite terminals, full mesh topology, distributed network, anti-jamming, and the like which are the special characteristics of the next generation military satellite communications system. Based on this, we present key research issues and evaluation on the issues by simulation.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.9
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• pp.60-67
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• 2013

Test cost reduction is necessary to test a complex System-on-a-Chip(SoC) which adopts various Intellectual Properties (IP). In this paper, test architecture with low pin count which is able to IP-based SoC test, using IEEE Std. 1149.7 and IEEE Std. 1500, is proposed. IEEE Std. 1500 provides independent access mechanism for each IP in IP-based SoC test. In this paper, just two test pins are required by composing that these independent access mechanism can be controlled by IEEE Std. 1149.7. The number of Chips which are tested at the same time is increased by reducing required test pin count at wafer and package level test, and consequently the overall manufacturing test cost will be reduced significantly.

• The Journal of the Korea Contents Association
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• v.11 no.2
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• pp.1-12
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• 2011

Movie contents requiring multiple shootings in places need much man power and many equipments. It is more serious in the case of multiple simultaneous shootings. In the points of small broadcasting companies, it is more difficult to cope with the situation, but it is also an essential task for the variety of video contents. We propose an one-person movie production scheme based on an IP camera-based live webcasting system which makes multiple shootings in places possible. It consists of three main functions of (1) collecting multiple video streams sent from IP cameras installed in places, (2) properly distributing them to Internet, and (3) receiving and editing them including recording video. By using the proposed scheme, we can be able to remotely utilize a new framework of Single-Person/ Multiple-Camera which beyonds the conventional Single-Person/Single-Camera framework. It becomes possible to take multiple simultaneous shoots in places. We can get an advantage of saving man power and time for producing various movie contents.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.307-317
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• 2012

Rapid development of the IT technology and mobile communications has increasingly improved many kinds of digital devices arise, as well as the mobile technology. However, the attacks (virus, hacking and Ip spoofing etc) have also increasingly grown dogged on any region including the society security. As the visual data is prone to copy, delete and move etc, it is necessary that attesting to the integrity of forensics evidence is crucial, as well as data transmission security. This paper presents a framework model using digital forensics method and the results of its performance evaluation for mobile security. The results show that the integrity of the visual data can be obtain with high security and make a proposal refer to prevention of Mobile IP Spoofing attack using our hashing data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.3
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• pp.165-169
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• 2002

Silicon wafer is very important accuracy make use semiconductor device substrate. In this research, for the uniformity dopant density distribution obtained to Neutron Transmutation Doping on make use Si in P Doping study work. In this research. we irradiated neutron on FZ silicon wafers which had high resistivity (1000~2000 ${\Omega}$cm), HANARO reactor was utilized resistivity changes due to observed, the generation of neutron irradiation on point defect analyzed, point defect on resistivity changes inquire into the effect. Before neutron irradiation theoretical due to calculated 5 ${\Omega}$-cm, 20.1 ${\Omega}$-cm for HTS hole and 5 ${\Omega}$-cm, 26.5 ${\Omega}$-cm, 32.5 ${\Omega}$-cm for IP3 hole. After neutron irradiation through SRP measurement the designed resistivities were approached, which were 2.1 H-cm for HTS-1, 7.21 ${\Omega}$-cm for HTS-2, 1.79 ${\Omega}$-cm for IP-1, 6.83 ${\Omega}$-cm for IP-2, 9.23 ${\Omega}$-cm for IP-3, respectively. Also after neutron irradiation resistivity changes due to thermal neutron dependent irradiation hole types free.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10B
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• pp.909-918
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• 2006

Recently, the qualities of the call and QoS of data service in mobile wireless IP networks inclusive of internet wired networks are very challenging issues. IntServ, DiffServ and MPLS model for supporting QoS in wired networks are representative models which are investigated generally up to now. While, MIPv4(Mobile IPv4) and MIPv6 are proposed to support mobility management for mobile wireless internet networks. But, MIPv4 and MIPv6 based UDP and TCP/IP protocol have many issues to be solved like efficient QoS and frequent handover management. In this paper, we propose a efficient management platform to support seamless data services and end-to-end QoS management in IP-based wireless mobility environments using transport layer protocol, SCTP which support multi-homing and multi-streaming. We used SCTP protocol and IntServ technology for end-to-end communications to support multi-homing and seamless QoS management in the IP-based mobile wireless networks.