• Journal of Communications and Networks
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• v.8 no.4
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• pp.461-474
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• 2006

A group key exchange protocol is a cryptographic primitive that describes how a group of parties communicating over a public network can come up with a common secret key. Due to its significance both in network security and cryptography, the design of secure and efficient group key exchange protocols has attracted many researchers' attention over the years. However, despite all the efforts undertaken, there seems to have been no previous systematic look at the growing problem of key exchange over combined wired and wireless networks which consist of both stationary computers with sufficient computational capabilities and mobile devices with relatively restricted computing resources. In this paper, we present the first group key exchange protocol that is specifically designed to be well suited for this rapidly expanding network environment. Our construction meets simplicity, efficiency, and strong notions of security.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.577-580
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• 2003

최근 차세대통합네트워크(NGN), ALL-IP 망 진화 방향과 함께 동기식과 비동기식 IMT-2000 망의 통합(Convergence) 또는 연동(Harmonization)에 관한 연구가 활발히 이뤄지고 있으며, 이동통신 망의 개방화에 대한 분위기가 점차 무르익어 가고 있다. 이러한 추세에 UMTS, cdma2000, WLAN 과 같은 서로 다른 방식의 무선 액세스 망으로부터 요구되는 무선인터넷 접속 요구를 하나의 통로로 연결하고 수용할 수 있는 모바일 액세스 통합 게이트웨이가 필요하다. 본 논문에서는 차세대 네트워크 발전 방향과 이동통신 망 개방의 흐름에 맞추어 동기식 망과 비동기식 IMT-2000 망에서 동시에 무선인터넷 서비스 접속을 제공하는 통합 게이트웨이 시스템(A-MiDAS)을 개발하기 위한 형상 설계 방법과 시스템 개발 시 고려사항 등에 대해서 기술한다.

• World Technopolis Review
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• v.3 no.3
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• pp.153-164
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• 2014

It is recent that STEM (Science, Technology, Engineering and Mathematics) education emerged as a great concern of the U.S. policy makers in terms of securing national and regional competitiveness. However, few attempts to embrace STEM education as a source for sustainable regional growth have been made mainly due to methodological challenges. This paper investigates the role of STEM education in achieving sustainable economic growth. For the purpose of the paper, a U.S. federal workforce development program named Workforce Innovation in Regional Economic Development (WIRED) in Southeastern Virginia that was implemented between 2007 and 2010 is selected and evaluated qualitatively. By identifying three themes as a result of three-stage coding methods, the evaluation results call for particular attention of local policy makers and key stakeholders to STEM education as a source of sustainable long-term economic growth in regions.

• Journal of the Semiconductor & Display Technology
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• v.3 no.4
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• pp.13-17
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• 2004

As the usage of wireless LAN becomes common in working environment, the number of database systems that support both wired and wireless users increases rapidly. The characteristics of wireless LAN that its speed is slow relatively comparing to wired network and the users in its environment connects to different communication points as they moves creates another challenge to be resolved in database systems. In the environment of hybrid communication systems, wired and wireless for voluminous data amount and a number of users, the two layer architecture of the conventional client-server database systems has limitation in the system performance. This is due to that server is the only point of data service in client-server database systems. In this paper, we discuss a new extended database system architecture that data services are distributed among servers and clients based on user database access patterns in order to improve system performance. We analyze the expected system performance by using simulation technique and prove the practical utilization of the system by demonstrating experimental results.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.59-60
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• 2006

TCP applied to the wireless-wired integrated network is the one that was applied to the existing wired network. In the wireless-wired integrated network, both wireless and congestion loss can occur. When wireless packet losses occur, the congestion control of TCP causes performance degradation by reducing its transmission rate. In this paper, we propose the algorithm to distinguish the wireless packet loss from congestion packet loss using MIB of the 802.11 MAC which has been generally used recently in wireless links.

• The KIPS Transactions:PartC
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• v.9C no.5
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• pp.637-646
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• 2002

In this paper, an implementation example of Java based MPEG-4 system that follows MPEG-4 standard protocols in order to provide multimedia-messaging service is introduced. The multimedia-messaging service is a wireless LAN based wired and wireless service that delivers multimedia contents including video and audio information. Detailed Methods to develop a MPEG-4 system like technology of MPEG-4 system implementation, definition for wired and wireless multimedia service, DMIF implementation, and mp4 file Parsing are described.

• Structural Monitoring and Maintenance
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• v.2 no.3
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• pp.237-252
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• 2015

This paper addresses the issue of reliability and performance in wireless sensor networks (WSN) based structural health monitoring (SHM), particularly with decentralized damage identification techniques. Two decentralized damage identification algorithms, namely, the autoregressive (AR) model based damage index and the Wiener filter method are developed for structural damage detection. The ambient and impact testing have been carried out on the steel beam structure in the laboratory. Seven wireless sensors are installed evenly along the steel beam and seven wired sensor are also installed on the beam to monitor the dynamic responses as comparison. The results showed that wireless measurements performed very much similar to wired measurements in detecting and localizing damages in the steel beam. Therefore, apart from the usual advantages of cost effectiveness, manageability, modularity etc., wireless sensors can be considered a possible substitute for wired sensors in SHM systems.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.4
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• pp.165-175
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• 2019

Networks use relatively slow heartbeat mechanisms, usually in routing protocols, to detect failures when there is no hardware signaling to help out. The time to detect failures available in the existing protocols is no better than a second, which is far too long for some applications and represents a great deal of lost data at 10 Gigabit rates. We compare the convergence time of routing protocol applying Bidirectional Forwarding Detection (BFD) protocol in wired mesh network topology. This paper suggests the combinations of protocols improving fail-over performance. Through the performance analysis, we contribute to reduce convergence time when system is fail-over.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.209-212
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• 2000

This paper discusses performance evaluation methodologies for wired/wireless Ethernet adaptors. This paper defines test cases for performance evaluation of LAN adaptor and its environments. Performance evaluation of LAN adaptor is mote complex as compared with interconnection devices such as Ethernet HUB and Ethernet switch, because its performance depends on the system on which the adaptor is plugged. Such dependencies include CUP type, RAM size, system bus architecture(PCI bus clock), etc.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.799-802
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• 2003

In this paper a FPGA implementation of WEP protocol is described. IEEE 802.11 specifies a wired LAN equivalent data confidentiality algorithm. WEP(Wired Equivalent Privacy) is defined as protecting authorized users of a wireless LAN from casual eavesdropping. WEP use RC4 algorithm for data encryption and decryption, also it use CRC-32 algorithm for error detection. The WEP protocol is implemented using Xilinx VirtexE XCV1000E-6HQ240C FPGA chip with PCI bus interface.