• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.811-814
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• 2015

There are many modern societies use the digital products in everyday life in the Middle, convenience, give him plenty of Bluetooth is one of the users. Bluetooth (IEEE 802.15.1) means equipment in the close range between the low-power wireless communication standard for the connection to use the technology. Currently, Bluetooth earphone, Bluetooth speaker, wearable mounted devices also used a lot because it takes people to exploit the benefits had been lifted and thereby increases your damage. So, reducing the damage the user's further research about the security technique that can stop completely. I am sure that many Bluetooth hacking techniques, a Bluetooth device firmware vulnerability within the stored data to allow the approach to attacking the BlueTooth Snarfing and want to analyze.

• The Journal of the Korea Contents Association
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• v.6 no.1
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• pp.8-13
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• 2006

In this thesis, an automatic door lock system using a dual tone multiple frequency(DTMF) signal generated as pushing the key button of mobile phone is proposed and implemented. This system consists of a transmitter module and a receiver module for processing the DTMF signal of mobile phone. The DTMF signal of mobile phone connected with ear-phone jack enter into the input terminal of DTMF receiver and those are encoded by a code-converter with 4-bits binary format in the DTMF receiver. The encoded output signals are transmitted to the amplitude shift keying(ASK) modulator of transmitter module and the modulated ASK signals which are converted into radio frequency(RF) signals propagate in a free space. The RF signals passed through a free space are demodulated by the ASK demodulator of receiver module and the demodulated ASK signals are sent to a micro-controller unit(MCU). The output signals processed by the MCU are compared with the secreted identification number which is prerecorded in a microprocessor and are transferred to a power relay. If the result is the same, the automatic door lock system opens a door. In the opposite case, it maintains closing the door. The implemented automatic door lock system operates well in mobile environments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.630-633
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• 2021

Microphones can convert received voice signals to electric signals. They have been widely used in various industries such as radios, smart devices and vehicles. Recently, the demands for small size and high sensitive microphones are increased according to the minimization of wireless earphone with the development of smart phone. A MEMS system is a good candidate for an ultra-small size microphone of a next generation and a read out IC for high sensitive MEMS sensor is researched from many industries and academies. Since the microphone system has a high sensitivity from environment noise and electric system noise, the system requires a low noise power supply and some low noise design techniques. In this paper, a low noise LDO is presented for small size MEMS microphone systems. The input supply voltage of the LDO is 1.5-3.6V, and the output voltage is 1.3V. Then, it can support to 5mA in the light load condition. The integrated output noise of proposed LDO form 20Hz to 20kHz is about 1.9uV. These post layout simulation results are performed with TSMC 0.18um CMOS technology and the size of layout is 325㎛ × 165㎛.

• Journal of Preventive Medicine and Public Health
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• v.6 no.1
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• pp.43-49
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• 1973

In this study noise source in a ward at four general hospitals in Seoul area has been investigated and analysed. The degree of reaction against noise by 171 randomly has also been examined. The results of the study have shown that the source of noise is the speakers of wired broadcasting or from visiting guests in two hospitals located in residential area. The patients at the two other hospitals located at commercial site have been suffered more from traffic noise. However, because of their separated living at hospital from their ordinary houselife, sixty one percent of the inpatients have wished a music sound of around 60 dB (A). After having considered the results of the investigation and wishes of the inpatients, following suggestions have been made: 1. Reduce the number of guests or their length of stay. 2. Wired broadcasting system should be substitued by wireless one, or if it's unavoidable, it should be used in office rooms only. 3. Since the stops and starts of vehicles induce much noise, Seoul City Government be requested to prepare an appropriate administrative measure for the vehicles around hospital area and it should prevent the establishment of new hospitals along high way site. 4. By using earphone, inpatients can choose a wireless channel according to each individual's taste. This through the masking effect, would cover up the noise source. 5. Rooms along the streets should be utilized as offices, otherwise double windows should be set up for inpatient's wards.