• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.5
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• pp.793-801
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• 2022

Most Bluetooth devices are commonly used in various ways these days, but they can be often lost due to small-size devices. However, most Bluetooth protocol do not provide authentication functions to legitimate owners, and thus someone who obtains the lost Bluetooth device can easily connect to their smart devices to use it. In this paper, we propose NBAS can authenticates legitimate owners using NFT on lossy Bluetooth devices.NBAS generates a digital wallet on the blockchain using the decentralized network Ethereum blockchain and facilitating the MAC address of the Bluetooth device in the digital wallet. The owner of the wallet uses a private key to certify the Bluetooth device using NFT. The initial pairing time of NBAS was 10.25 sec, but the reconnection time was 0.007 sec similar to the conventional method, and the pairing rejection time for unapproved users was 1.58 sec on average. Therefore, the proposed NBAS effectively shows the device authentication over the conventional Bluetooth.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.5
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• pp.47-52
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• 2004

In this paper we fabricated microchip antenna operating in bluetooth frequency bands(2.402∼2.4800㎓). The antenna has a size of about 54mm${\times}$19mm${\times}$0.8mm giving a total bluetooth PCB for suuort and chip of about 11mm${\times}$4mm${\times}$1.6mm. Bandwidth of the designed and fabricated chip antenna for bruetooth is 10.71% at the resonated frequency of 2.45㎓ and the resonant frequency and bandwidth versus change of my arbitrary fled point is observed. also, E-plane and H-plane in the Measured radiation pattern characteristic of chip antenna is compared and analyzed.

• Journal of Korea Multimedia Society
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• v.6 no.1
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• pp.161-166
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• 2003

This paper presents a high gain LNA for a bluetooth application using 0.25$\mu\textrm{m}$ CMOS technology. The conventional one stage LNA has a low power gain. The presented one stage LNA using a cascode inverter LNA with a voltage reference and without a choke inductor has an improved Power gain. Simulation results of the 2.4GHz designed LNA shows a high power gain of 21dB, a noise figure of 2.2dB, and the power consumption of 255mW at 2.5V power supply.

• Journal of Sensor Science and Technology
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• v.29 no.5
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• pp.283-292
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• 2020

Current sensors that use a Hall element and Hall IC to measure the magnetic fields generated in steel silicon core gaps do not distinguish between direct and alternating currents. Thus, they are primarily used to measure direct current (DC) in industrial equipment. Although such sensors can measure the DC when installed in expensive equipment, ascertaining problems becomes difficult if the equipment is set up in an unexposed space. The control box is only opened during scheduled maintenance or when anomalies occur. Therefore, in this paper, a method is proposed for facilitating the safety management and maintenance of equipment when necessary, instead of waiting for anomalies or scheduled maintenance. A Bluetooth 4.0 low-energy current-sensor system based on near-field communication is used, which compensates for the nonlinearity of the current-sensor output signal using a piecewise linear model. The sensor is controlled using its generic attribute profile. Sensor nodes and cell phones used to check the signals obtained from the sensor at 50-A input currents showed an accuracy of ±1%, exhibiting linearity in all communications within the range of 0 to 50 A, with a stable output voltage for each communication segment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.829-834
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• 2009

In this paper, a HediaFLO/GPS/Bluetooth antenna is designed for mobile handset with metallic chassis. It is consisted of two metal plates with 7.6 mm gap, a connection plate and source between two plates. It can be analyzed as U-slot antenna of $0.5\;{\lambda}$, array of shorted patches each application bands. Simulated and measured performance of the proposed antenna show that it has enough possibility to reuse metallic chassis itself as radiator without any additional space for antenna.

• Journal of Korea Multimedia Society
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• v.6 no.2
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• pp.325-331
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• 2003

In this paper, we designed a spiral inductor and voltage controlled oscillator with the negative resistor for the bluetooth receiver by using 0.25$\mu\textrm{m}$ 1-poly 5-metal CMOS n-well process. The proposed inductor, which applies multi layer metal structure, is a structure that decreases resistance value by increasing he metal thickness. As the resistance value decreases, the quality factor Q has improved. Also, voltage-controlled oscillator is designed applying 1 port negative resistance, and changes its oscillating frequency by varying outside capacitor values. The simulation results show that oscillating frequency is 2.33~2.58GHz changing from 2pF to 14pF, and the oscillator has oscillating power over 0dBm.

• Journal of Korea Multimedia Society
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• v.5 no.2
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• pp.206-214
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• 2002

In this paper, it is designed and verified the baseband system that performs various protocol functions of specification of the Bluetooth system. In order to verify the developed circuits, various baseband functions are tested by using the ModelSim simulator. The developed circuits operate at 4MHz main clock. Test suite includes hap selection function, generation of the sync word, error correction(1/3 rate FEC, 2/3 rate FEC), HEC generation/checking, CRC generation/checking, data whitening/dewhitening and packet trans/reception procedure. etc. As a result of the simulation, it is verified that the developed baseband system conform to the specification of the Bluetooth system.

• ETRI Journal
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• v.26 no.3
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• pp.229-240
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• 2004

This paper reports on our development of a dual-mode transceiver for a CMOS high-rate Bluetooth system-onchip solution. The transceiver includes most of the radio building blocks such as an active complex filter, a Gaussian frequency shift keying (GFSK) demodulator, a variable gain amplifier (VGA), a dc offset cancellation circuit, a quadrature local oscillator (LO) generator, and an RF front-end. It is designed for both the normal-rate Bluetooth with an instantaneous bit rate of 1 Mb/s and the high-rate Bluetooth of up to 12 Mb/s. The receiver employs a dualconversion combined with a baseband dual-path architecture for resolving many problems such as flicker noise, dc offset, and power consumption of the dual-mode system. The transceiver requires none of the external image-rejection and intermediate frequency (IF) channel filters by using an LO of 1.6 GHz and the fifth order onchip filters. The chip is fabricated on a $6.5-mm^{2}$ die using a standard $0.25-{\mu}m$ CMOS technology. Experimental results show an in-band image-rejection ratio of 40 dB, an IIP3 of -5 dBm, and a sensitivity of -77 dBm for the Bluetooth mode when the losses from the external components are compensated. It consumes 42 mA in receive ${\pi}/4-diffrential$ quadrature phase-shift keying $({\pi}/4-DQPSK)$ mode of 8 Mb/s, 35 mA in receive GFSK mode of 1 Mb/s, and 32 mA in transmit mode from a 2.5-V supply. These results indicate that the architecture and circuits are adaptable to the implementation of a low-cost, multi-mode, high-speed wireless personal area network.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.275-281
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• 2018

Along with the growing market for pets and the increasing interest in pet management, the need for pet management systems is increasing. Development of IoT-related technologies has made it possible to develop the related systems. This paper implements a variety of functions through Bluetooth 4.0 and LoRa communication between devices using Arduino and Android applications depending on distances. In the paper, users can receive real-time location information through the communication between Android applications and devices attached to pets, store pet information, manage pet information, and store stroll courses more conveniently with the developed system.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.4
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• pp.119-125
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• 2007

In this paper, a miniaturized PCB-integrated antenna is proposed for bluetooth applications. The proposed antenna is a modified form of the printed inverted F antenna where the size reduction is achieved by employing the meander strip for the resonant length part of the radiator. The antenna dimension is optimized using the commercial electromagnetic software MWSTM. The designed antenna is fabricated by the standard photo-etching technique and its performance is measured. The fabricated antenna shows a bandwidth of 125MHz centered at 2.45GHz and a gail of -0.23dBi. The size of the proposed antenna is $9.65mm{\times}5.95mm$ corresponding to the 55 percent of the area of the existing printed inverted F antenna.