• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.5
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• pp.832-842
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• 2006

Wireless Personal Area Networks(WAPANs) are designed for short-range ad hoc connectivity among portable devices. They have gained much attention in the industry recently. One of them, High-rate WPAN, is designed to support multimedia traffic that requires high data rates. But, High-rate WPAN standards don't specify the time slot assignment scheduling method of CAT(Channel Time Allocation). So, there has been many studies regarding time slot assignment scheduling of CAT. However, present studies involve demerits about not applying various types of errors in air interlace or having a starvation of a specific DEV(data device). In this paper, we propose algorithms about supplying the intermediate channel assignment in order to avoid these demerits. This method will help other methods that use time slot assignment scheduling of CTA.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.66.1-66.1
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• 2012

Although all printed cost-less radio frequency identification (RFID) tags have been considered as a core tool for bringing up a ubiquitous society, the difficulties in integrating thin film transistors (TFTs), diodes and capacitors on plastic foils using a single in-line printing method nullify their roles for the realization of the ubiquitous society1,2. To prove the concept of all printed cost-less RFID tag, the practical degree of the integration of those devices on the plastic foils should be successfully printed to demonstrate multi bit RFID tag. The tag contains key device units such as 13.56 MHz modulating TFT, digital logic gates and 13.56 MHz rectifier to generate and transfer multi bit digital codes via a wireless communication (13.56 MHz). However, those key devices have never been integrated on the plastic foils using printing method yet because the electrical fluctuation of fully printed TFTs and diodes on plastic foils could not be controlled to show the function of desired devices. In this work, fully gravure printing process in printing 13.56 MHz operated 32 bit RFID tags on plastic foils has been demonstrated for the first time to prove all printed RFID tags on plastic foils can wirelessly generate and transfer 32 bit digital codes using the radio frequency of 13.56 MHz. This result proved that the electrical fluctuations of printed TFTs and diodes on plastic foils should be controlled in the range of maximum 20% to properly operate 32 bit RFID tags.

• Journal of Digital Convergence
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• v.10 no.11
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• pp.419-425
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• 2012

In these days, the trends of home networking system is implementation of easily configured system with home security of emergency alarm and visitor verification services. In this paper, we implemented push server system based on Arduino of open source physical computation platform to verify visitors for the homes without home networking services. In the suggested system, visitor verification is performed in and out of home, and home access security of the system could be constructed with low-cost price by use of windows push server system and smart devices with alarm operation in corresponding to not allowed access trying.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.4
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• pp.728-736
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• 2007

The more improved the Internet and the information technology, the stronger cryptographic system is required which can satisfy the information security on the platform of personal hand-held devices or smart card system. This paper introduces a case study of designing an elliptic curve cryptographic processor of a high performance that can be suitably used in a wireless communicating device or in an embedded system. To design an efficient cryptographic system, we first analyzed the operation hierarchy of the elliptic curve cryptographic system and then implemented the system by adopting a serial cell multiplier and modified Euclid divider. Simulation result shows that the system was correctly designed and it can compute thousands of operations per a secdond.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.208-210
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• 2014

IOT(Internet of Things) through Radio Frequency Identification (RFID), Wireless Sensors, Global Positioning Systems, Laser Scanners and other information sensing device, according to the agreed protocol keep anything connected to the Internet for information exchange and communication. It's a network what in order to achieve intelligent identify, locate, track, monitor and manage. With the development of IOT technology, data growth will explode once again on the existing basis, which gives data management enormous challenges. This paper described characteristics of data in IOT and analysis existing data management technologies, then proposed a data management framework to conduct the research on the data management of IOT.

• Journal of Aerospace System Engineering
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• v.13 no.2
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• pp.10-18
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• 2019

In this paper, we present the results of a developed LTE/Wi-Fi-based video transmission system which can be applied in small unmanned aerial vehicles of 25kg or less. The developed video transmission system comprised of airborne datalink terminal, ground datalink terminal, and used LTE and Wi-Fi wireless data communication technologies to transmit videos of resolution higher than HD (720p/30fps, 1080p/30fps) taken by small UAV. The airborne device is designed to efficiently transmit real-time streaming video through the incorporation of H.264 video processing board. Ground tests and evaluation indicated the possibility of the developed system to transmit real-time videos from close distance in regards to non-line-of-sight area.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.9
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• pp.3120-3137
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• 2021

Small-sized IoT wireless sensing devices can be deployed with small aircraft such as drones, and the deployment of mobile IoT devices can be relocated to suit data collection with efficient relocation algorithms. However, the terrain may not be able to predict its shape. Mobile IoT devices suitable for these terrains are hopping devices that can move with jumps. So far, most hopping sensor relocation studies have made the unrealistic assumption that all hopping devices know the overall state of the entire network and each device's current state. Recent work has proposed the most realistic distributed network environment-based relocation algorithms that do not require sharing all information simultaneously. However, since the shortest path-based algorithm performs communication and movement requests with terminals, it is not suitable for an area where the distribution of obstacles is uneven. The proposed scheme applies a simple Monte Carlo method based on relay nodes selection random variables that reflect the obstacle distribution's characteristics to choose the best relay node as reinforcement learning, not specific relay nodes. Using the relay node selection random variable could significantly reduce the generation of additional messages that occur to select the shortest path. This paper's additional contribution is that the world's first distributed environment-based relocation protocol is proposed reflecting real-world physical devices' characteristics through the OMNeT++ simulator. We also reconstruct the three days-long disaster environment, and performance evaluation has been performed by applying the proposed protocol to the simulated real-world environment.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.2
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• pp.15-27
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• 2019

This paper deals with a web-based public address system for conveying information for different institutions. An architecture for a Short Messaging Service (SMS) based public address (PA) system that can be programmed by an authorized mobile phone or device is proposed. This PA system will facilitate information transfer from heads of offices, managers, directors, and deans of the institutions to its constituents or unit area as well as enable postings of information with proper authentication and validation remotely. The system supports high priority messaging, allowing the conveyance of critical and time sensitive information. The mobility management support for the PA system will be based on the Hierarchical Mobile Internet Protocol version 6 (HMIPv6), hence, allowing for a seamless connectivity to the system. The major advantage of this proposed PA system as compared with the traditional electronic displays and bulletin boards is seamless mobility wherein the display devices can be programmed remotely by heads of the institutions and business organization. It also allows faster communication and immediate actions concerning the different institutions, organizations, and businesses, thus, ensuring high productivity.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.36-45
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• 2007

Today Human Personal Trainers are becoming very famous in this health conscious world. They teach user to achieve fitness goals in managed way. Due to their high fee and tight schedule they are unavailable to mass number of people. Another solution to this problem is to develop digital personal trainer portable instrument that may replace human personal trainers. We developed a portable digital exercise trainer device - BIOFIT that manages, monitors and records the user's physical status and workout during exercise session. It guides the user to exercise efficiently for specific fitness goal. It keeps the full exercise program i.e. exercises start date and time, duration, mode, control parameter, intensity in its memory which helps the user in managing his exercise. Exercise program can be downloaded from the internet. During exercise it continuously monitors the user's physiological parameters: heart rate, number of steps walked, and energy consumed. If these parameters do not range within prescribed target zone, the BIOFIT will alarm the user as a feedback to control exercise. The BIOFIT displays these parameters on graphic LCD. During exercise it continuously records the heart rate and number of steps walked every 10 seconds along with exercise date and time. This stored information can be used as treatment for the user by an exercise expert. Real-time ECG monitoring can be viewed wirelessly (RF Communication) on a remote PC.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.4
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• pp.285-296
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• 2005

Reduced pressure chemical vapor deposition technology has been used to study SiGe heterostructure epitaxy and device issues, including SiGe relaxed buffers, proper control of Ge component and crystalline defects, two dimensional delta doping, and their influence on electrical properties of devices. From experiments, 2D profiles of B and P presented FWHM of 5 nm and 20 nm, respectively, and doses in 5×10/sup 11/ ∼ 3×10/sup 14/ ㎝/sup -2/ range. The results could be employed to fabricate SiGe/Si heterostructure field effect transistors with both Schottky contact and MOS structure for gate electrodes. I-V characteristics of 2D P-doped HFETs revealed normal behavior except the detrimental effect of crystalline defects created at SiGe/Si interfaces due to stress relaxation. On the contrary, sharp B-doping technology resulted in significant improvement in DC performance by 20-30 ％ in transconductance and short channel effect of SiGe HMOS. High peak concentration and mobility in 2D-doped SiGe heterostructures accompanied by remarkable improvements of electrical property illustrate feasible use for nano-sale FETs and integrated circuits for radio frequency wireless communication in particular.