• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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• pp.2711-2733
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• 2018

Minimizing power consumption in bandwidth limited optical traffic grooming networks is presented as a two-objective optimization problem. Since the main objective is to route a connection, the network throughput is maximized first, and then the minimum power consumption solution is found for this maximized throughput. Both transparent IP over WDM (Tp-IPoWDM) and translucent IP over WDM (Tl-IPoWDM) network may be applied to examine such bi-objective algorithms. Simulations show that the bi-objective algorithms are more energy-efficient than the single objective algorithms where only the throughput is optimized. For a Tp-IPoWDM network, both link based ILP (LB-ILP) and path based ILP (PB-ILP) methods are formulated and solved. Simulation results show that PB-ILP can save more power than LB-ILP because PB-ILP has more path selections when lightpath lengths are limited. For a Tl-IPoWDM network, only PB-ILP is formulated and we show that the Tl-IPoWDM network consumes less energy than the Tp-IPoWDM network, especially under a sparse network topology. For both kinds of networks, it is shown that network energy efficiency can be improved by over-provisioning wavelengths, which gives the network more path choices.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2005.05a
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• pp.88-92
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• 2005

The Ubiquitous life is not a life style that exists in a science fiction or in a far distance future anymore. The Combination of electronic and physical space, this new type of space was created by the ubiquitous network system, and this system will offer us new life style. Also the pattern of our living will be changed by the information that has obtained from this ubiquitous network system. By offering a new way of communication from the ubiquitous surrounding, our life style such as shopping, medical treatment, banking, and working conditions and a notion such as the preference in a job title would have shifted. This study have arrived at the development of the high technology, in other words Ubiquitous age , I have considered the notion of home-network that have observed by the preceding investigators as well as the theoretical consideration of residential space in ubiquitous surrounding. After I look into the usages and examples of residential space in ubiquitous surrounding of today's society, I hope that this would be helpful for the design that strives for the comfortable living in this ubiquitous age.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.61-64
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• 2003

Technological progress in integrated, low-power, CMOS communication devices and sensors makes a rich design space of networked sensors viable. These sensors can be deeply embedded in the physical world and spread throughout sensor network environment like smart dust. So ubiquitous computing will be come true. SmartDust project is the one of ubiquitous computing approach. It produces TinyOS, mote(mica, mica2, rene2, mica2dot, etc.), NesC, TinyDB, etc. We constructs sensor network test bed and tests to approach sensor network and ubiquitous computing.

• The KIPS Transactions:PartC
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• v.14C no.3 s.113
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• pp.239-254
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• 2007

Ubiquitous computing supports environment to freely connect to network without restrictions of place and time. This environment enables easy access and sharing of information, but because of easy unauthorized accesses, specified security policy is needed. Especially, ubiquitous sensor network devices use limited power and are small in size, so, many restrictions on policies are bound to happen. This paper proposes double-key based light weight security protocol, independent to specific sensor OS, platform and routing protocol in ubiquitous sensor network. The proposed protocol supports safe symmetric key distribution, and allows security manager to change and manage security levels and keys. This had a strong merit by which small process can make large security measures. In the performance evaluation, the proposed light weight security protocol using double-key in ubiquitous sensor network allows relatively efficient low power security policy. It will be efficient to ubiquitous sensor network, such as smart of ace and smart home.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.9
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• pp.4398-4417
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• 2017

Multi-user Multiple-Input and Multiple-Output (MU-MIMO) has potential for prominently enhancing the capacity of wireless network by simultaneously transmitting to multiple users. User selection is an unavoidable problem which bottlenecks the gain of MU-MIMO to a great extent. Major state-of-the-art works are focusing on improving network throughput by using Channel State Information (CSI), however, the overhead of CSI feedback becomes unacceptable when the number of users is large. Some work does well in balancing tradeoff between complexity and achievable throughput but is lack of consideration of fairness. Current works universally ignore the rational utilizing of time resources, which may lead the improvements of network throughput to a standstill. In this paper, we propose TOUSE, a scalable and fair user selection scheme for MU-MIMO. The core design is dynamic-time-warping-based user selection mechanism for downlink MU-MIMO, which could make full use of concurrent transmitting time. TOUSE also presents a novel data-rate estimation method without any CSI feedback, providing supports for user selections. Simulation result shows that TOUSE significantly outperforms traditional contention-based user selection schemes in both throughput and fairness in an indoor condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1336-1340
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• 2011

In this paper, the efficient prevention of cross talk technique for basically avoiding the confusion problem between the overlapped ubiquitous network of the other object is developed within the same area. The intelligent unified wireless network remote meter reading system of the ubiquitous ZigBee base is developed based on this technology. Therefore, in this paper, each meter reading equipments managed the information of its own adjacent ZigBee channel. The intelligent network system steadily transmitting data a relay was developed based upon this information in each region through the flexible channel conversion technique.

• Journal of information and communication convergence engineering
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• v.5 no.1
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• pp.73-77
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• 2007

This paper discusses the implementation of a rehabilitation center based on a ubiquitous sensor network. This paper discusses the implementation of a rehabilitation center based on a ubiquitous sensor network. We recognize that certain mild conditions requiring rehabilitation may be treated with minimal human supervision. In place of this constant human supervision, a variety of sensors are used to monitor the patient and rehabilitation progress. These sensors send data through a wireless Zigbee network to a server which stores the data and makes it available to a rehabilitation expert for analysis. This rehabilitation expert also issues rehabilitation prescriptions which are created based on the expert's determination of the patient's condition. By having the ability to control the rehabilitation equipment used, strictly enforce the assigned prescription, and constantly monitor the patient for any warning signs, the system ensures a safe and optimal rehabilitation session.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.2
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• pp.190-195
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• 2007

As Ubiquitous era comes, it became necessary to construct environment which can provide more useful information to human in the spaces where people live like homes or offices. On this account, network of the peripheral devices of Ubiquitous should constitute efficiently. For it, this paper researched human pattern by classified motion recognition using sensors module data. (This data processing by Neural network and fuzzy algorithm.) This pattern classification can help control home network system communication. I suggest the system which can control home network system more easily through patterned movement, and control Ubiquitous environment by grasp human's movement and condition.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.80-85
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• 2014

In this paper, we propose and analyze a novel synchronization scheme for ubiquitous home network system. In ubiquitous home network system, synchronization method is very important because many consumer electronic devices send the data simultaneously to each other through infrastructure such as access point. We employ digital watermarking sequence to improve synchronization performance without system overhead. The performance of proposed scheme is analyzed in terms of correlation performance. The results of the paper can be applied to design of various applications for ubiquitous home network systems.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.255-257
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• 2004

The study for ubiquitous computing infra is proceeding actively, it make possible to use service and access network anywhere, anytime because of wire/wireless communication technology and progress of hardware. Domestically, study for the network mobility support technology which is the key technology for future ubiquitous computing realization have progressed, but that is insufficient. Especially, there is no study for independent mobility support study about railway wireless network. So, this study propose network mobility management technology for mobile network infra in railway and proper network model in train.