• The Journal of the Korea Contents Association
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• v.11 no.4
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• pp.101-111
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• 2011

Due to recent development in wireless communication technologies and mobile information devices, the services on ubiquitous computing technology without time and place restriction have been spotlighted. Moreover, the interest of the Wireless Sensor Networks (WSNs) and context-awareness technologies have largely been escalating and their technologies utilization is active in the various applications such as healthcare, farm management and so on. However, the direct adaption of the existing context-awareness technique to the WSN technology has several drawbacks as follows. First, such systems waste precious energy of sensor nodes, due to unnecessary data transmissions. Secondly, since the existing work was designed to support only specific applications, it is required to implement a new context-awareness application for a specific purpose. Therefore, we, in this paper, propose a new real-time monitoring system based on context-awareness in WSNs. Our system not only enhances energy efficiency by reducing data transmissions by doing context-awareness on a sensor node, but also is scalable in terms of supporting new context-awareness functionalities through modularization.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.5
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• pp.495-501
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• 2013

This paper describes a flexible wireless telemetering system using a mesoscale cantilever sensor, which is microfabricated with a patterned thin Ni-Cu foil on a resin substrate. The dynamic validation of the sensor has been conducted in a flow. The wireless telemetry is used to obtain data regarding the oscillating flows. It is shown that the sensor is nearly independent of the environmental temperature and is suitable for application to primary healthcare and diagnostic devices. It can be easily integrated with other modules for measuring physiological parameters, e.g., blood pressure, oxygen saturation, and heart rate, to increase the convenience and reliability of diagnosis. The precision and reliability of the sensor are also dependent on the design of the analog front-end and noise reduction techniques. It is shown that the present system's minimum interval between packet transmissions is ~16 ms.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.2050-2055
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• 2012

Since the wireless sensor networks become pervasive, various application-specific requirement have been emerged and suggested. Among them, reliability and real-time service are ones of big research challenges since sensed information is useless if a packet is lost and delivered later than deadline. Even though many research works have been proposed, they was designed to meet one of both requirements. To solve above problem, in this paper, we propose how to extend current protocol to meet two requirements together. More detailed, Mint Route protocol is revised to meet specific real-time requirement, (m,k)-firm stream in wireless sensor networks. Since the main operations in MintRoute are very similar to definition of (m,k)-firm stream, extension is achieved by modifying some parts of procedure. Finally, the simulation results are given and analyzed to validate the its suitability for reliable and real-time requirement.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.1
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• pp.175-181
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• 2015

In this paper, we develop a 2.4GHz ISM band wireless communication platform prototype based on embedded linux which support can be u-Hospital service. The developed system is available connecting between ARM920T processor board and FPGA board and linking IEEE 802.11b PHY board, AD/DA(10Bit) and RF(2.4GHz) board for wireless access. It is also can be utilized for the embedded system design with IEEE 802.11b/g Access Point(Option: IEEE 802.11a/b/g) test due to the Embedded Linux. Also, the developed system is possible to test and verify the radio access technology, Modem(OFDM etc) and IP(Intellectual Property) circuit. And make the most use of the system, we search for a expansion to that home and mobile healthcare, wellness service application.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.6
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• pp.64-72
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• 2009

In this paper, a high efficiency 2.45 GHz rectenna with a microstrip patch antenna and a dual-mode band-pass filter in which the 2nd and 3rd harmonics are suppressed, is presented. From the experimental results, the 2.45GHz rectenna using 3rd harmonic suppressed dual-mode BPF shows the conversion efficiency of 41.6% with incident power density of 0.3 mW/cm2 and the received power of 1.66 mW. This result shows high conversion efficiency because the received power of this rectenna is lower than other rectennas to be compared with. This rectenna can be applied to the WPT (Wireless Power Transmission) field for energy harvesting. Also, it is expected to be used to provide the stand-by power for the low power devices for USN, and wireless power transfer in sensor application of MEMS devices.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.141-150
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• 2005

Wireless Sensor Networks have been rapidly developed due to the advances of sensor technology and are expected to be applied to various applications in many fields. In Wireless Sensor Networks, schemes for managing the network energy-efficiently are most important. For this purpose, there have been a variety of researches to suggest routing protocols. However, existing researches have ideal assumption that all sensor nodes have sensing data to transmit. In this paper, we designed and implemented a sensing-aware cluster selection algorithm based on LEACH-C for the sensor network in which part of sensors have sensing data. We also simulated proposed algorithm on several network situation and analyzed which situation is suitable for the algorithm. By the simulation result, selecting cluster head among the sensing nodes is most energy-efficient and the result shows application of sensing-awareness in cluster head selection when not all sensors have sensing data.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.2
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• pp.1-6
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• 2010

Short-range wireless communication systems are expanding at rapid rate, finding application in offices and homes. Development of wireless local network is accompanied by steady increase in the demand for ever higher data rates. This in turn entails the necessity to develop communication systems which operate at higher frequencies. It can be expected that short-rage wireless communication networks will soon push towards the THz frequency range. We use a 3D ray-launching for analysis of propagation environments at the indoor fixtures. We extended the approach from the modeling of the reflectivity of optically thick, smooth building materials at THz frequencies to materials with a rough surface. The simulation result of propagation environment is similar to average received power of reference paper. The RMS delay spread was calculated to be 9.11 ns in a room size of $6m(L){\times}5m(W){\times}2.5m(H)$ for the concrete plaster.

• Journal of IKEEE
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• v.22 no.3
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• pp.723-728
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• 2018

This paper proposes a signal detection method for IoT door lock system which is a new application field of VLC (Visible Light Communication). This paper describes the signal detection technique for user recognition that needs to be overcome in order to apply VLC to door lock system which has a demand for new technology due to security issue. This system has security and high signal detection characteristics because it uses existing infrastructure to communicate with visible light. In order to detect the signal using FFT, the signal of the user who accesses the authentication channel based on the pilot signal is detected, and the performance of the false alarm probability and detection probability is shown in the channel model.

• Journal of the Korean Geotechnical Society
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• v.34 no.9
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• pp.19-32
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• 2018

In this study, the applicability and practicality of landslides monitoring by using wireless sensor network (WSN) was analysed. WSN system consists of a sensor node for collecting and transmitting data using IEEE 802.14e standard, a gateway for collecting data and transmitting the data to the monitoring server. In the topology of the sensor network, a highly flexible and reliable mesh type was adopted, and three testbeds were chosen in each location of Seoul metropolitan area. Soil moisture sensors, tensiometers, inclinometers, and a rain gauge were installed at each testbed and sensor node to monitor the landslide. For the estimation of the optimal network topology between sensor nodes, the susceptibility assessment of landslides, forest density and viewshed analysis of terrain were conducted. As a result, the network connection works quite well and measured value of the volumetric water content and matric suction simulates well the general trend of the soil water characteristic curve by the laboratory test. As such, it is noted that WSN system, which is the reliable technique, can be applied to the landslide monitoring.

• Convergence Security Journal
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• v.17 no.4
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• pp.3-9
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• 2017

Recently, Wireless communication has been widely used as a short distance communication medium in various industrial fields as well as communication connection between home appliances due to the appearance of the Internet of Things. And Most commonly used wireless communication media include WiFi, Bluetooth, and NFC. Among them, Bluetooth is widely used for communication between smart devices as well as computer peripheral devices. And Bluetooth in the home network fields is being used to control electronic products. However, since Bluetooth security vulnerabilities are known, more and more attacks are being exploited. As the application range of Bluetooth is expanding, it is necessary to prepare countermeasures accordingly. Therefore, this study investigates the security threat factors of through Bluetooth'attack case and attack technology. And By proposing countermeasures against this problem, we intend to utilize it as data for improving the security of wireless network service in the future.