• Journal of KIISE:Information Networking
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• v.34 no.1
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• pp.48-61
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• 2007

WiBro (Wireless Broadband) service, developed in Korea, can provide the host mobility while its users hang around within the subnet. Next-generation Internet protocols, IPv6 and Mobile IPv6 (MIPv6), provide a plenty of addresses to the nodes and enable the handover between different subnets. However, MIPv6 is not enough to support a real time service such as VoIP (Voice over IP) due to the long latency, and it is necessary to develop an enhanced handover mechanism which is optimized to the WiBro networks. In this paper, we suggest an improved fast handover mechanism while the mobile node moves around WiBro networks. The proposal is based on Fast Mobile IPv6 (FMIPv6) which is the representative protocol for fast handover, and reduces the handover latency by the close interaction between the link layer (WiBro MAC) and IP layer (FMIPv6). Finally, we analyze the performance of proposed mechanism through the mathematical analysis.

• Journal of Multimedia Information System
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• v.7 no.3
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• pp.221-230
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• 2020

Used optimization techniques as solution for mobile network have been implemented as a reference systems for various applications against fading and signals perturbation, in addition each transition to 5th generation telecommunication standards require a deep studies in order to park an applied instantaneous process. The paper describes a preliminary planning and a careful preparation to update both subscriber radio access network as well as data transmission network this approach conducts to make network resource updates invisible for customers and with minimal costs for mobile operators basically in terms of delay. In addition, network operators transit to mobile networks, multimedia services efficient delivery are considered the challenging application and the most promising for mobile network operators today, this work conduct to optimize video consumption of mobile users which are exponentially increasing. The interference is a complex phenomenon in mobile radio telecommunication system, and a mobile phone can be a source of interference to another one. Actual advances in technology necessitate the need for the complicated software solution that can take several unexpected phenomena in consideration to rise to a level higher than ever. The capability needs today require the use of Drive test which is used to take the performance of network in the field by using a special software called TEMS investigation, it have been implemented as standalone systems for various applications. The paper focuses on considering as the best technical for optimization of mobile networks, analysis and processing of signal, a Drive Test is the method used to take the performance of network in the field by using a special software called TEMS investigation. Most used in the world, this software is reputed to detect and analyze many problems of mobile network between the mobile phone and the transmitter: BTS in case of GSM and Node B for UMTS. An example of that is interference in radio communication. It exists permanently and it degrades considerably the quality of received signal when it exceeds certain levels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5B
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• pp.840-848
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• 2010

This paper proposes a proactive authentication scheme using credentials based on chameleon hashing in MIH environments. There is a proactive authentication structure defined by IEEE 802.21 Security Study Group for the link access in MIH environment. Both schemes based on EAP and on PKI can be applied to such structure, but the former has caused network traffic due to the complicated authentication procedure and the latter has complex structure for managing certificates. The proposed scheme performs the proactive authentication procedure only between a mobile node and a MIH Key Holder by using credentials based on chameleon hashing. Our scheme reduces the network traffic since authentication with the server is unnecessary in MIH environment and PKI structure is not required as well. In addition, the proposed scheme provides secure PFS and PBS features owing to the authenticated Diffie-Hellman key exchange of the chameleon-based credential.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.1
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• pp.40-47
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• 2015

We propose a method to provide a selective VoD service during live streaming sessions. In the proposed method, each peer joined the live streaming session receives video stream packets with P2P manner and stores the packets to provide a VoD service. To mitigate the overhead of each peer node to store the video stream packets, the proposed scheme categorizes peers into three different groups based on their link types. To increase data gathering speed and reduce the network load, we also proposes the P2P transmission scheme within the same AP network for the peers with Wi-Fi link. To evaluate the performance of the proposed method, we implement computer simulator using NS-3. Simulation results show that the proposed method reduces the overhead about 66% and increases the P2P data gathering speed about 50% compared to the conventional schemes.

• Convergence Security Journal
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• v.16 no.6_2
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• pp.83-88
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• 2016

Over recent years there has been considerable growth in interest in the use of biometric systems for personal authentication. Biometrics is a field of technology which has been and is being used in the identification of individuals based on some physical attribute. By using biometrics, authentication is directly linked to the person, rather than their token or password. Biometric authentication is a type of system that relies on the unique biological characteristics of individuals to verify identity for secure access to electronic systems. In 2013, Althobati et al. proposed an efficient remote user authentication protocol using biometric information. However, we uncovered Althobati et al.'s protocol does not guarantee its main security goal of mutual authentication. We showed this by mounting threat of data integrity and bypassing the gateway node attack on Althobati et al.'s protocol. In this paper, we propose an improved scheme to overcome these security weaknesses by storing secret data in device. In addition, our proposed scheme should provide not only security, but also efficiency since sensors in WSN(Wireless Sensor Networks) operate with resource constraints such as limited power, computation, and storage space.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.75-84
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• 2014

In order to solve the problems such as overload, single point of failure, non-optimized data path, and network scalability in conventional central mobility management protocols, distributed mobility management schemes have been continually studied in and around the IETF. In this paper, a network-based partially-distributed mobility management mechanism, pDMMv6, is suggested and the performance comparison with traditional protocols such as PMIPv6 and MIPv6 is made through simulation under the various user traffic environment. The simulation results include UDP packet delivery ratio, end-to-end packet delay, binding delay for registration signaling, CPU utilization in each node, and response delays in several server-client TCP applications such as web browsing, e-mail, telnet remote login, FTP file up/down-load, and database access.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.180-186
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• 2017

In this paper we propose a traffic aware Demand Wakeup MAC(TADW-MAC) protocol, in which low data delay and high throughput can be achieved, for wireless sensor networks. With the TADW-MAC protocol, the problem of the DW-MAC protocol, which schedules only one packet to deliver during the Sleep period in a multi-hop transmission is resolved. DW-MAC is not adequate for the applications such as object tracking and fire detection, in which busty data should be transmitted in a limited time when an event occurs [6-8]. When an event occurs, duty cycle can be adjusted in the TADW-MAC protocol to get less energy consumption and low latency. The duty cycle mechanism has been widely used to save energy consumption of sensor node due to idle listening in wireless sensor networks. But additional delay in packet transmission may be increased in the mechanism. Our simulation results show that TADW-MAC outperforms RMAC and DW-MAC in terms of energy efficiency while achieving low latency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12B
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• pp.728-734
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• 2007

In this paper, we propose a GOSST(Grade Of Services Steiner minimum Tree) heuristic mechanism for the design of a physical multiple security grade network with minimum construction cost. On the network, each node can communicate with other nodes by its desiring security grade. Added to the existing network security methods, the preventing method from illegal physical access is necessary for more safe communication. To construct such network with minimum cost, the GOSST problem is applied. As the GOSST problem is a NP-Hard problem, a heuristic with reasonable complexity is necessary for a practical solution. In this research, to design the physical multiple security grade network with the minimum construction cost, the reformed our previous Distance Direct GOSST heuristic mechanism is proposed. The mechanism brings average 29.5% reduction in network construction cost in comparison with the experimental control G-MST.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.22-33
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• 2014

As a standard of WMNs, IEEE 802.11s supports two kinds of MAC algorithm: a mandatory EDCA used by IEEE 802.11e and an optional MCCA. While EDCA classifies traffic according to four Access Categories (AC) and offer differentiated service using a classified priority, MCCA can guarantee the specific bandwidth of users with a TDMA-style bandwidth reservation scheme between mesh routers. In case that a flow is VBR traffic of a multimedia application, MCCA has disadvantage that the reserved bandwidth does not be used entirely, though it guarantees required bandwidth of users and fairness using bandwidth reservation with neighbors' node. In this paper, we showed a problem that is wastes the reserved bandwidth when MCCA is enabled and proposed a new scheduling algorithm to prevent waste of bandwidth and to improve network utilization effectively, named Resource Sharing Round Robin (RSRR) scheduling. Finally we showed simulation results that performance of a proposed RSRR is better than the legacy MCCA through NS-2 simulation.

• Pediatric Infection and Vaccine
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• v.20 no.3
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• pp.186-189
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• 2013

Endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) now provides an important alternative diagnostic modality in patients with intrathoracic tuberculosis lymphadenopathy. The procedure is well tolerated in the outpatient setting, provides access to the mediastinal and hilar lymph node locations commonly in tuberculosis and also allows bronchial washing to be performed at the same procedure. However, there is no report of EBUS-TBNA applied to children to diagnose tuberculosis. We report a case of EBUS-TBNA applied to children who had intrathoracic tuberculosis lymphadenopathy.