• 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.49-56
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• 2006

This paper describes the design and the verification of IEEE 802.15.4 LR-WPAN 2.4GHz Physical layer for Ubiquitous Sensor Network(USN). We designed the Carrier Frequency Offset(CFO) compensation satisfied the frequency tolerance of IEEE 802.15.4 LR-WPAN and the adaptive matched filter that re-setting of the threshold for the symbol synchronization of the various USN environment. The multiplications is reduced 1/16 by this method each other at i, q phases and has 0.5dB performance improvement in detection probability. Proposed baseband system is designed with verilog HDL and implemented using FPGA prototype board.

• Journal of IKEEE
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• v.20 no.3
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• pp.322-325
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• 2016

This paper proposed Enhanced Segmentized Clear Channel Assesment(ESCCA) for the IEEE 802.15.4 networks. This method divides original CCA into two groups to check precise channel status and perform additional CCA to increase throughput performance. Through the proposed method, the device can access the channel more often, so the transmission efficiency of the IEEE 802.15.4 network improves. To confirm the feasibility and usability of the proposed method, computer simulation has been performed. In the simulation, a star topology with one coordinator and a lot of devices is considered and the traffic flows are all one way, with the communication directed to the coordinator. Simulation results_ show the proposed method is improving maximum 10 kbps of throughput and decreasing maximum 15 of the average number of total CCA than IEEE 802.15.4 CCA method.

• Journal of the Korea Society for Simulation
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• v.25 no.4
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• pp.43-52
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• 2016

Wireless sensor network (WSN) technology has been implemented using commercial off-the-shelf microcontrollers (MCUs), In this paper, we propose a simulation environment to realize the physical evaluation of FPGA-based node by considering vertically cross-layered WSN in terms of physical node device and network interconnection perspective. The proposed simulation framework emulates the physical FPGA-based sensor nodes to interoperate with the NS3 through the runtime infrastructure (RTI). For the emulation and interoperation of FPGA-based nodes, we extend a vendor-providing FPGA design tool from the host computer and a script to execute the interoperation procedures. The standalone NS-3 is also revised to perform interoperation through the RTI. To resolve the different time-advance mechanisms between the FPGA emulation and event-driven NS3 simulation, the pre-simulation technique is applied to the proposed environment. The proposed environment is applied to IEEE 802.15.4-based low-rate, wireless personal area network communication.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.1
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• pp.1-14
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• 2010

It is recently issued scalability, mobility and external internet connection on Wire-less sensor network. The low power wireless sensor networks based on IPv6 technology 6LoWPAN technology is being standardized in the IETF. This paper for the 6LoWPAN environment based on the routing protocol LOAD, route cost applied the packet re-transmission rate which follows in Link Qualities price which uses at course expense and packet transmission Minimum route Cost routing protocol where does on the course wherethe smallest packet re-transmission becomes accomplished proposed. The technique which proposes compared and LOAD and AODV that about 13%, about 16% energy consumption is few respectively averagely, Energy of the entire network equally, used and energy effectiveness and improvement of network life time experiment led and confirmed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.4
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• pp.647-656
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• 2020

Recently, there has been an increasing number of cases in which important data (personal information, technology, etc.) of national and public institutions are leaked to the outside world. Surveys show that the largest cause of such leakage accidents is "insiders." Insiders of organization with the most authority can cause more damage than technology leaks caused by external attacks due to the organization. This is due to the characteristics of insiders who have relatively easy access to the organization's major assets. This study aims to present an optimized property selection model for detecting such abnormalities through supervised learning algorithms among machine learning techniques using actual data such as CrossNet data transfer system transmission log, e-mail transmission log, and personnel information, which safely transmits data between separate areas (security area and non-security area) of the business network and the Internet network.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.153-161
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• 2007

Stroke is the second most significant disease leading to death in Korea. The conventional therapeutic approach is mainly based on physical training, however, it usually provides the limited degree of recovery of the normal brain function. The electric stimulation therapy is a novel and candidate approach with high potential for stroke recovery. The feasibility was validated by preliminary rat experiments in which the motor function was recovered up to 80% of the normal performance level. It is thought to improve the neural plasticity of the nerve tissues around the diseased area in the stroked brain. However, there are not so much research achievements in the electric stimulation for stroke recovery as for the Parkinson's disease or Epilepsy. This study aims at the developments of a wireless variable pulse generator using ZigBee communication for future implantation into human brain. ZigBee is widely used in wireless personal area network (WPAN) and home network applications due to its low power consumption and simplicity. The developed wireless pulse generator controlled by ZigBee can generate various electric stimulations without any distortion. The electric stimulation includes monophasic and biphasic pulse with the variation of shape parameters, which can affect the level of recovery. The developed system can be used for the telerehabilitation of stroke patient by remote control of brain stimulation via ZigBee and internet. Furthermore, the ZigBee connection used in this study provides the potential neural signal transmission method for the Brain-Machine Interface (BMI).

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.5
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• pp.724-729
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• 2008

This paper presents the calculation of the required bandwidth of common frequency bandwidth applying queueing theory for maximizing the efficiency of frequency resource of WPAN(Wireless Personal Area Network) based Digital acoustic and communication devices. It assumed that LBT device(ZigBee) and FH devices (DCP, RFID and Bluetooth) coexist in the common frequency band for WPAN based Digital acoustic and communication devices. Frequency hopping (FH) and listen before talk (LBT) have been used for interference avoidance in the short range device (SRD). The LBT system transmits data after searching for usable frequency bandwidth in the radio wave environment. However, the FH system transmits data without searching for usable frequency bandwidth. The queuing theory is employed to model the FH and LBT system, respectively. As a result, the throughput for each channel was analyzed by processing the usage frequency and the interval of service time for each channel statistically. When common frequency bandwidth is shared with SRD using 250mW, it was known that about 35 channels were required at the condition of throughput 84%, which was determined with the input condition of Gaussian distribution implying safety communication. Therefore, the common frequency bandwidth is estimated with multiplying the number of channel by the bandwidth per channel. These methodology will be useful for the efficient usage of frequency bandwidth.

• The KIPS Transactions:PartC
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• v.17C no.1
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• pp.1-14
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• 2010

IEEE 802.15.4[1] has been standardized for the physical layer and MAC layer of LR-PANs(Low Rate-Wireless Personal Area Networks) as a technology for operations with low power on sensor networks. The standardization is applied to the variety of applications in the shortrange wireless communication with limited output and performance, for example wireless sensor or virtual wire, but it includes vulnerabilities for various attacks because of the lack of security researches. In this paper, we analyze the vulnerabilities against the denial of sleep attacks on the MAC layer of IEEE 802.15.4, and propose a detection mechanism against it. In results, we analyzed the possibilities of denial of sleep attacks by the modification of superframe, the modification of CW(Contention Window), the process of channel scan or PAN association, and so on. Moreover, we comprehended that some of these attacks can mount even though the standardized security services such as encryption or authentication are performed. In addition to, we model for denial of sleep attacks by Beacon/Association Request messages, and propose a detection mechanism against them. This detection mechanism utilizes the management table consisting of the interval and node ID of request messages, and signal strength. In simulation results, we can show the effect of attacks, the detection possibility and performance superiorities of proposed mechanism.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.8
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• pp.1349-1355
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• 2008

Recently many short-range transceiver systems, such as ZigBee, Bluetooth and RFID(Radio Frequency Identification), have been developed. These systems are mostly low-power transceivers. In the near future many more low-power transceivers are appeared for WPAN(Wireless Personal Area Network) and interference mitigation technologies are necessary to the low-power transceivers for using frequency resources efficiently. In this paper we consider two methods for sharing frequency resources. The first case is that a frequency band previously assigned fer a certain system is shared and the second case is that the white frequency band is shared. We study the method and conditions for sharing frequency resources in the above two cases. When a frequency band is shared with ZigBee, RFID, DCP (Digital Cordless Phone) and Bluetooth as an example for the first case, the sharing conditions are investigated and the results are presented. We propose a balancing factor to maintain an equal transmitting conditions between systems having a different interference mitigation technique. In the interference simulation we use FH(Frequency Hopping) as a reference system and 0.9 of a balancing factor for LBT(Listen Before Talk) and 0.8 for DS(Direct Spreading). From the simulation results we know that a balancing factor reduces interference probability therefore many more systems can be operated in the same frequency bands compared with the case without using a balancing factor.