• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.6
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• pp.113-123
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• 2010

In this paper, an efficient network configuration method is proposed for mobile nodes in LR-WPAN (Low Rate Wireless Personal Area Network) based on the IEEE 802.15.4 standard. The proposed MSBS (mobile sensor beacon setup) method can be used to implement a joining procedure by which an improved processing rate can be achieved. This improvement is achieved by using BOP (Beacon only Period). In this method, the performance of mobile nodes is enhanced by using information on depth, traffic, and RSSI (Received Signal Strength Indication). By using the MSBS method, trusted data can be transferred and traffic overloads that occur at specific nodes can be prevented. The information obtained from the mobile nodes in wireless networks is analyzed using the proposed method, in order to study the performance of the method. Simulation results show that the MSBS method can be used to obtain an efficient network configuration according to the mobility of nodes in LR-WPAN.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.9 s.100
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• pp.941-948
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• 2005

In this paper, we have proposed a Ultra-Wideband slot notch antenna by using a semi-circular extension. The proposed antenna cover the entire UWB band(3.1${\~}$10.6 GHz) and notch out the IEEE 802.1la frequency band(5.15${\~}$5.825 GHz) by inserting a $\lambda$/4 length slot into the patch. A prototype antenna was fabricated on FR-4( ${\epsilon}_r$ =4.4, substrate thickness=0.8 mm) and measured for VSWR characteristics. The measured notched frequency variations versus frequency for different slot length. The path loss and group delay were measured. The proposed antenna also show a good gain flatness(1.9 dBi) except the IEEE 802.1la frequency band.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.1145-1148
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• 2005

The sensor network that may be deemed to fall in the field of ubiquitous computing performs the basic function of transmitting sensing data through the autonomous sensing and the Ad hoc network. In order to collect and treat various sensing data at the time of application and manage extremely limited system resources, the sensor network requires the embedded operating system that uses low power, a small cord size and the least hardware resources. In this paper, The operating system having a new structure for constructing the IEEE 802. 15.4 MAC and Zigbee sensor network is suggested and can be formed by reviewing the characteristics and the core structural requirements of the operating system for the sensor network based on operating systems, which have been formed under existing similar conditions, and applying such features and core structural requirements to the design of the operating system for achieving the features and the requirements.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.685-690
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• 2013

This paper has proposed a multi-channel and wide gain-range baseband circuit blocks for the IEEE 802.15.4g MR-OFDM SUN systems. The proposed baseband circuit blocks consist of two negative-feedback VGAs, an active-RC 5th-order chebyshev low-pass-filter, and a DC-offset cancellation circuit. The proposed baseband circuit blocks provide 1 dB cut-off frequencies of 100 kHz, 200 kHz, 400 kHz, and 600 kHz respectively, and achieve a wide gain-range of +7 dB~+84 dB with 1 dB step. In addition, a DC-offset cancellation circuit has been adopted to mitigate DC-offset problems in direct-conversion receiver. Simulation results show a maximum input differential voltage of $1.5V_{pp}$ and noise figure of 42 dB and 37.6 dB at 5 kHz and 500 kHz, respectively. The proposed I-and Q-path baseband circuits have been implemented in $0.18-{\mu}m$ CMOS technology and consume 17 mW from a 1.8 V supply voltage.

• Journal of Advanced Navigation Technology
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• v.11 no.3
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• pp.233-238
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• 2007

In this paper, a wireless sensor network system was embodied inside the shipping for digital ship. First, the analysis of radio environment inside ship are investigated. As a result, it was confirmed that a wireless sensor network system can be applied inside the ship. Using Shipboard Wireless Sensor Network System based on IEEE 802.15.4 technique, we designed, and made the prototype of Zigbee Node and RFID Reader. We could be sensing on shipboard and testing entrance of crew by using Zigbee Node and RFID Reader. The sensing and exit or entry control data are transmitted a server system through internet that connected Wireless Gateway with AP, so we can monitoring the saved data on shipboard database.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9A
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• pp.837-843
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• 2006

IEEE802.15.3 and IEEE802.15.4 have defined the hybrid MAC protocols based on TDMA and CSMA where a multi-frame TDMA structure is employed so that multiple data frames can be transmitted within one timeslot to guarantee minimum delay bounds of isochroous traffic. However, TDMA has an intrinsic problem that cannot dynamically allocate optimal length of timeslot to each station. Therefore the idle timeslot can be produced by stations when each transmission queue is instantaneously empty during its timeslot, which would waste lots of timeslots especially in the multi-frame TDMA systems. In this paper, we propose a more flexible multiple-access scheme for the multi-frame TDMA system based on the concept of virtual slot which is accessible by every station with the highest priority for slot owner and lower priority for other stations. Finally, our simulation results from various environments show that proposed scheme can achieve magnitude improvement of total system throughput and average message delay by maximizing channel utilization.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.2
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• pp.312-318
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• 2011

USN technology will be applied to various fields such as logistics, transportation, government, health, welfare and environment and will be settled down by basic infrastructure of a future society. In this study, we analyzed sensor networks structure based on IEEE 802.15.4 and implemented the sensor monitoring system using Zigbee modules. For implementation of real-time sensor monitoring system, we designed Linux-based development environment and the sensor-specific component. The result of this paper may be utilized in such areas lighting system, intrusion detection, fire detection, detection and notification of abnormal conditions.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.98-103
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• 2021

In this study, we propose a group communication technique that guarantees security and expandability by configuring a network consisting of IoT terminals equipped with security functions. As the number of devices participating in the network increases, network resources are proportionally reduced, and adding a security function to the IoT device increases the delay time due to encryption in the IoT device. If the error rate that occurs in the network increases, network resources are quickly consumed due to retransmission. Therefore, IoT terminals are grouped to ensure scalability while supporting security, reducing the consumption of network resources even when the number of participating nodes increases, thus ensuring scalability. For the future implementation, the encryption method used in IoT terminals considered the standard of IEEE802.5.4, and the standardization trend was investigated and classified. The proposed method applies IoT devices that provide security functions of the IEEE802.5.4 standard to the group communication base to ensure reliability and scalability. In the performance evaluation, the effectiveness of the proposed method was confirmed by comparing the delay times when grouping IoT devices with security functions through simulation.

• Journal of Internet of Things and Convergence
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• v.6 no.4
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• pp.15-19
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• 2020

In this paper, we propose a optimal CW(Conention Window) synchronization scheme in IEEE 802.11 WLANs. IEEE 802.11 WLANs support DCF(Distributed Coordination Function) mode for the MAC(Medium Access Control) operation. In DCF, the CW increases exponentially according to the collisions and becomes minimum CW according to the success of data transmissions. However, since the base minimum CW value is hardware or standard specific, the number of active stations and network status are not considered to determine the CW value. Even though the researches on optimal CW have beend conducted, they do not consider the optimal CW synchronization among mobile stations which occur network performance degradation. Therefore, this paper calculates the optimal CW value and shares it with mobile stations in the network.

• Journal of the Korea Society for Simulation
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• v.17 no.4
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• pp.89-97
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• 2008

In wireless personal area networks (WPANs), the successful design of channel time allocation algorithm is a key factor in guaranteeing the various quality of service (QoS) requirements for the stringent real-time constraints of multimedia services. In this paper we propose a channel time allocation algorithm for achieving a high quality transmission and high channel error tolerance of MPEG stream in the IEEE 802.15.3 high-rate wireless PANs. Our algorithm exploits the characteristics of MPEG stream. When a new MPEG stream arrives, a DEV models it by the traffic envelope and delivers the traffic envelope to the piconet coordinator (PNC) along with the channel time request. The PNC performs channel time allocation according to the envelope. Performance of the proposed scheme is investigated by simulation and analysis. Our results show that compared to conventional scheme, the proposed scheme is very effective and provides a good performance under typical channel error conditions.