• Journal of Digital Contents Society
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• v.7 no.4
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• pp.301-308
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• 2006

There are some technologies such as USN, RFID, Home-network to advance the ubiquitous era. Those technologies embody Context-Awareness System. To Context-Awareness System is that human, objects and environment supply information with cable and wireless at real time. So private information, information privacy, a wide sense privacy will be faced on serious menace. In this article, I analyze threat of private information in Context-Awareness System under USN(ubiquitous Sensing Network) surroundings and present technology to protect private information. Each technology can apply subdivided protection province information privacy. I expect definition of information privacy, insight through technological presentation and total solution in this article.

• Journal of the Korea Society of Computer and Information
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• v.17 no.12
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• pp.121-129
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• 2012

In this paper, we proposed WBAN system model to management an application that requires low rate data transfer in IEEE 802.15.4. We have to use different wireless sensor network technology to transfer different date rate and emergency message in medical application service. A suitable system model for WBAN and a WBAN MAC protocol in order to solve these existing system problems are proposed. Firstly, the priority queuing was applied to contention access period, and the system model which could guarantee transmission of a MAC command frame was proposed. Secondly, the MAC frame was newly defined to use the system model which was proposed above. Thirdly, WBAN CSMA/CA back-off algorithm based on data transmission rate was proposed to enhance data throughput and transmission probability of the data frame which does not have priority in the proposed WBAN system. The proposed algorithm is designed to be variable CSMA/CA algorithm parameter, depending on data rate. For the evaluation of WBAN CSMA/CA algorithm, we used Castalia. As a result of the simulation, it is found that the proposed system model can not only relieve loads of data processing, but also probability of collision was decreased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6C
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• pp.561-570
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• 2009

Ultra-wideband communication systems based on impulse radio have merits that are possible for the high data rate transmission, high resolution ranging are positioning system. Conventionally, in order to accomplish these features, the high-speed ADC (Analog to Digital Convertor) is necessary to apply radio determination system operating in time domain. However, considering low rate - wireless personal area network (LR-WPAN) aims to low-cost hardware implementation, the expensive ADC converting GHz sampling per second is not appropriate. So, this paper introduces a low complex AR (Auto Regressive) model based non-coherent ranging scheme operating in frequency domain with using low-speed ADC utilizing analog Voltage Control Oscillator (VCO) mode for the frequency domain transformation. To verify the superiority of the proposed ranging and location algorithm working in frequency domain, the suggested IEEE 802.15.4a TG channel model is used to exploit affirmative features of the proposed algorithm with conducting the simulation results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2C
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• pp.145-152
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• 2009

Ultra-wideband communication systems for impulse radio have merits that are possible for either high resolution ranging system or radio determination. Conventionally, in order to accomplish these functions, the rapid analog to digital convertor (ADC) is necessary to apply radio determination system operating in time domain. However, considering that low rate - wireless personal area network (LR-WPAN) aims to low-cost hardware implementation, the expensive ADC converting GHz sampling per second is not appropriate. So, this paper introduces the high resolution ranging system operating in frequency domain with using low sampling rate ADC, and a new non-coherent ranging scheme utilizing analog Frequency Modulation (FM) mode for the frequency domain transformation. To verify the superiority of the proposed ranging algorithm working in frequency domain, the suggested IEEE 802.15.4a TG channel model is used to exploit affirmative features of the proposed algorithm with conducting the simulation results.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.5
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• pp.33-41
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• 2009

In this paper, we propose a scheme for voice data retransmission in LR-WPAN to support the required QoS even in the severe channel error environments. In IEEE 802.15.4a, as the user data rate is supported up to 850Kbps, the voice streaming data can be transferred more easily. In this research, we study the beacon-enabled mode in IEEE 802.15.4 LR-WPAN standard with 250Kbps data rate. In the proposed scheme, special slots are dynamically assigned for retransmission of the packet that fails during a voice service, and in the severe channel error environments a time diversity is acquired. Analytical results show that the proposed scheme is more robust and achieves a much higher throughput than the previous protocol in LR-WPAN.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.8 s.350
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• pp.25-34
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• 2006

In this paper DynaMoNET is suggested as a novel IPv6-based multi-homed mobile network architecture which is composed of nested mobile ad hoc networks dynamically coming together through wireless personal area networks. Each ad hoc network has a mobile router which may work as a root mobile router instead of fixed mobile routers in a DynaMoNET. A root mobile router provides the reliable Internet connectivity for the entire mobile network. This paper includes a innovative handover protocol for multi-homed mobile networks, network switchover algorithm considering multiple decision factors, root mobile router election process based on token-based algorithm fast root mobile router discovery algorithm and fault avoidance mechanism to support reliable Internet connectivity. Finally the system architecture of a mobile router is given in detail.

• Journal of Korea Multimedia Society
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• v.12 no.3
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• pp.419-426
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• 2009

The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC) protocol based on UWB for high speed wireless home networks and WPANs. The WiMedia D-MAC fundamentally removes the problems of the centralized MAC revealed at IEEE 802.15.3 MAC, by adopting a distributed architecture. However, there is no completely distributed method for allocating fair data rates to all traffic streams by considering each stream's QoS parameter. In this paper, a novel fair distributed QoS admission control method is proposed. The proposed method is a fair, adaptive QoS provisioning method, by allocating time slots to devices according to the current traffic load condition, through executing only a proposed single satisfaction of QoS (SoQ) algorithm at each device.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.12
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• pp.1395-1402
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• 2015

An electric heat tracing system manages the temperature of pipes used in a plant. We propose a Zigbee-based wireless system so called the TESCON(: TEmperature Sensing and CONtrol) to monitor and control the electric heat tracing system in an integrated way. Simulations have been done to analyze the performance of the TESCON system. The performance of the TESCON system is validated by obtaining similar results via testbed operation. We also suggest an extension method of the TESCON system based on the hierarchical tree topology by adopting techniques such as network partition, channel reuse and frame aggregation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.10
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• pp.35-42
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• 2011

WPAN(Wireless Personal Area Network) have many advantages such as using low power and cheap price, small size. So it is recently increasing application range such as personal portable device, home network and sensor network so and on. IEEE 802.15.3 basically has the point to point or peer to peer UM(Usage Model). But using devises that need data transmission is increasing in the house and office. Therefor UM of point to multipoint is proposed. In this paper, I proposed Multicast ACK mechanism on the point to multipoint UM. So it is able to transfer data to multiple devices as this Multicast transfer method at a time. Thus, throughput performance is improved. But the problem that increases data transfer delay is appeared because of adding Multicast ACK traffic. We compared the performance between standard and proposed mechanism through a numerical analysis.

• Journal of Korea Spatial Information System Society
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• v.11 no.1
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• pp.115-126
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• 2009

Recent development in wireless communication and mobile positioning technologies makes Location-Based Services (LBSs) popular. However, because, in the LBSs, users request a query to database servers by using their exact locations, the location information of the users can be misused by adversaries. Therefore, a mechanism for users' privacy protection is required for the safe use of LBSs by mobile users. For this, we, in this paper, propose a efficient cloaking region creation scheme using Hilbert curves in distributed grid environment, so as to protect users' privacy in LBSs. The proposed scheme generates a minimum cloaking region by analyzing the characteristic of a Hilbert curve and computing the Hilbert curve values of neighboring cells based on it, so that we may create a cloaking region to satisfy K-anonymity. In addition, to reduce network communication cost, we make use of a distributed hash table structure, called Chord. Finally, we show from our performance analysis that the proposed scheme outperforms the existing grid-based cloaking method.