• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.5
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• pp.959-975
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• 2011

Wireless mesh networks enlarge the wireless coverage area by interconnecting relatively stationary wireless routers (mesh routers). As wireless mesh networks are envisioned to provide high-bandwidth broadband Internet service to a large community of users, the Internet gateway, which acts as a central point of Internet attachment for the mesh networks, is likely to suffer heavily from the scramble for shared wireless resources because of aggregated traffic toward the Internet. It causes performance decrement on end-to-end transmissions. We propose a scheme to balance the load in a mesh network based on link quality variation to different Internet gateways. Moreover, under the mesh coverage, mobile nodes can move around and connect to nearby mesh routers while still keeping the connections to the Internet through the best gateway in terms of link quality. In this structure, gateways perform the balancing procedure through wired links. Information about gateways and mobile node's location is distributed appropriately so that every mesh router can quickly recognize the best gateway as well as the positions of mobile nodes. This distributed information assists mobile nodes to perform fast handoff. Significant benefits are shown by the performance analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1950-1956
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• 2007

IEEE 802.16e has many points to be improved. Among them, fast handover is essential when user moves in high speed. In this paper we proposed a fast handover scheme using handover candidate BS set. This scheme is based on IEEE 802.16e, however according to the performance evaluation results through simulation; our proposed scheme shows more than 30% of handover delay reduction and at least 5% of handover drop probability improvement.

• International Journal of Computer Science & Network Security
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• v.22 no.12
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• pp.245-251
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• 2022

In this paper, a high gain, broadband planar vivaldi antenna (PVA) by utilizing a broadband stripline feed is developed for wireless communication for IoT systems. The suggested antenna is designed by attaching a tapered-slot construction to a typical vivaldi antenna, which improves the antenna's radiation properties. The PVA is constructed on a low-cost FR4 substrate. The dimensions of the patch are 1.886λ₀×1.42λ₀×0.026λ₀, dielectric constant Ɛ_r=4.4, and loss tangent δ=0.02. The width of the feed line is reduced to improve the impedance bandwidth of the antenna. The computed reflection coefficient findings show that the suggested antenna has a 46.2% wider relative bandwidth calculated at a 10 dB return loss. At the resonance frequencies of 6.5 GHz, the studied results show an optimal gain of 5.82 dBi and 85% optimal radiation efficiency at the operable band. The optometric analysis of the proposed structure shows that the proposed antenna can achieve wide enough bandwidth at the desired frequency and hence make the designed antenna appropriate to work in satellite communication and medical internet of things (M-IoT) healthcare applications.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2155-2158
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• 2003

A term of home automation that was in fashion only a few years ago has not been used any more. Nowadays, We have been used a term of home network or digital home than home automation much. While internet infra is diffused at home, data network corp., communication corp., electric appliance corp. and home automation control system corp. which we did not mind each other particularly constructed consortium, and they have designs on home network market. Also, cellular phone's growth tried home networking by using not only wired internet but also broadband wireless communication. Regardless, many solutions are coming out it is few to be applied to real life because the standard is not determined with the protocol each other. Therefore, we developed home network system using USB(Universal Serial Bus) that has the possibility most in home networking standard. The mobile USB home control system is excellent at expansibility and portability. Also we can complete low cost and stable system using an embedded system.

• Journal of information and communication convergence engineering
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• v.4 no.2
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• pp.58-61
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• 2006

A key issue toward mobile multimedia communications is to create technologies for broadband signal transmission that can support high quality services. Such a broadband mobile communications system should be able to overcome severe distortion caused by timevarying multi-path fading channel, while providing high spectral efficiency and low power consumption. For these reasons, an adaptive suboptimum decision feedback equalizer (DFE) for the single-carrier shortburst transmissions system is considered as one of the feasible solutions. For the performance improvement of the system with the short-burst format including the short training sequence, in this paper, the multiple-training least mean square (MTLMS) based DFE scheme with soft decision feedback is proposed and its performance is investigated in mobile wireless channels throughout computer simulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.184-184
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• 2008

In this paper, a power divider with a multi-band and broadband are designed and fabricated using an InGaP/GaAs process. The design of this divider is based on multi-band because it is important in the next generation IMT-Advances system. In this design, power divider is fabricated with the frequency of 824 MHz to 894 MHz, 1.8 GHz to 2.2 GHz and 2.3 GHz to 2.4 GH for cellular, personal communication system (PCS) and Wireless Broadband Internet (WiBro). The topology of the designed power divider is based on the multi-section and fabricated using integrated passive device (IPD) library of nanoENS Inc. It is measured using network analyzer.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1320-1323
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• 2002

This paper reviews the Korean government’s selection process of core wireless communications technologies, and presents technology trends, perspectives and strategies of 5 core technologies to develop in wireless communications areas based on the mid term IT technology development plan(2002∼2004). Delphi Panel Method and Analytic Hierarchy Process(AHP) Analysis were adapted to select 30 core technologies in 9 strategic areas. Especially, 5 core wireless communications technologies out of 24 required technologies are selected: 4 G Core Technology, Broadband Wireless Access Network Technology, IMT-2000 Plus STP Technology, OBP Based Multimedia Satellite Communications Technology, Stratosphere Communications System Technology. Strategic national IT R&D program has been essential to continue success story of CDMA technology, and acquiring technology independency from advanced nations. In long term perspectives, a strategy of intensive investment with prudent selection onto core technologies should be deployed in the IT R&D programs. Also, the national IT R&D programs should be limited in the high risk & high returen areas where only government can afford the failures as well as better spill over effects are expected for the technology development and national economy. Korean industry has some strength in wireless communications technology area. Therefore, more policy concerns should be given into this area not only to secure present strength but also to explore better technology competitiveness.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.81-86
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• 2008

The paradigm of information & communication is rapidly changed into ubiquitous environment based electromagnetic wave, and antenna technology in the wireless ubiquitous communication is remarkably developed. Mini chip antenna has its within small card compared to the external AP antenna. Designed and Fabricated WLAN antenna has a broadband characteristics of 2.4~2.5GHz and 4.9~5.85GHz, and can be used triple mode of IEEE 802.11.a,g.b, and it has comparatively a constant performance in the dual frequency band.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.3
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• pp.288-293
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• 2010

In these information-communication society, the wireless system technologies are increasing to do all things with wireless solution for fast and convenient works. This trend drives ubiquitous solutions which are based on broadband wireless network that gives network connection whenever, everywhere. This paper deals a bookshelf management system using plower line communication and RFID module. This system includes a 900 MHz RFID reader, Passive RFID-Tags, an Atmeg128 microprocessor board attached LED Display Module, and a management PC with GUI Software. This system works well in power line communication, tag reading and LED display, and PC Management Software.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.6
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• pp.823-829
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• 2011

This paper covers the service quality of packet-based voice service that is provided over a wireless broadband (WiBro) network. Using a measurement software that has been developed in the course of preparing a advanced service quality management scheme for the packet-based voice service over a wireless network[2][3], a huge scale of experiment is conducted to measure the real quality of the voice service. Based on our analysis of the measurement result, the service quality of the voice service is supposed to be quite good over WiBro networks. In addition, another experiment to investigate the effect of degradation of wireless transmission conditions on the service quality of the voice service shows the values of wireless service metris in which mean opinion score (MOS) starts to decrease.