• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.7-17
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• 2015

In this paper, we propose a single antenna SSD(simultaneous single band duplex) system using turbo equalizer. The proposed system communicates simultaneously on single band. That is the proposed system is full-duplex system. The proposed system uses balanced feed network circuit to improve isolation in single antenna structure. Also, the proposed system uses RF(radio frequency) cancellation and digital cancellation to cancel self-interference. Additionally, the proposed system uses turbo equalizer to equalize ISI(inter-symbol interference) by harsh multipath fading and to collect bit errors by residual self-interference signals. By using turbo equalizer, the proposed system guarantees QoS(quality of service). In this paper, we uses Simulink simulation program to analyze performance of the proposed system. The simulation results confirm that proposed system can communicate simultaneously by using balanced feed network, RF cancellation, digital cancellation and turbo equalizer in harsh multipath channel on single band.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.1
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• pp.67-75
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• 2008

RFID(Radio Frequency Identification) system is an automated identification system that consists of tags and readers. They communicate with each other by RF signal. As a reader can identify many tags in contactless manner using RF signal, RFID system is expected to do a new technology to substitute a bar-code system. But RFID system creates new threats to the security and privacy of individuals, Because tags and readers communicate with each other in insecure channel using RF signal. So many people are trying to study various manners to solve privacy problems against attacks, but it is difficult to apply to RFID system based on low-cost Gen2. Therefore, We will propose a new encryption scheme using matrix based on Gen2 in RFID system in paper, and We will analyze our encryption scheme in view of the security and efficiency through a simulation and investigate application environments to use our encryption scheme.

• Journal of electromagnetic engineering and science
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• v.8 no.3
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• pp.114-118
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• 2008

Direct-conversion RF front-end for 5-GHz WLAN is implemented in $0.18-{\mu}m$ CMOS technology. The front-end consists of a low noise amplifier, and low flicker noise down-conversion mixers. For the mixer, an inductor is included to resonate out parasitic tail capacitances in the transconductance stage at the operating frequency, thereby improves the flicker noise performance of the mixer, and the overall noise performance of the front-end. The receiver RF front-end has 6.5 dB noise figure, - 13 dBm input IP3, and voltage conversion gain of 20 dB with the power consumption of 30 mW.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.549-552
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• 2011

RFID technology is one of the verification technology that use radio frequency. Use and study of RFID are on the increase because RFID is a one of main technologies in ubiquitous. In this paper, we address to develop a Record Processing System using RFID. The purpose of this paper is improvement of accuracy and efficiency on Record Processing System by applying RFID. Later, This paper will be able to help to establish of u-Campus.

• Journal of Biosystems Engineering
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• v.27 no.5
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• pp.459-466
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• 2002

In Korea, a need of automatic dairy farm management system has been increased to lower production cost and to strengthen international competition. However, the present management system was mostly relied on foreign technologies and caused some problems in post management and after-sales services. Therefore, though there is a problem of price and quality at present, domestic technologies of the management system should be developed for the long run. This study was conducted to develop an electronic identification unit for an automatic dairy farm management system. The developed system was consisted of a tag, a reader, a switching circuit, and a personal computer. The tag attachable to each individual cow was developed to transmit individual radio frequency(RF) code into the air with modulation of ASK(amplitude shift keying). And the switching circuit was added to avoid confusion on reception and transmittance. The reader attached to a feeding device was developed to transmit activating signal periodically and to identify code of the individual tag when the tag was approached to the device. The reader was consisted of an active filter, a detecter, a comparator and a microcontroller. The test result was feasible enough to apply it for the automatic farm management system and the identified maximum distance was about 37cm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.221-226
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• 2009

A nonlinear curve shaped radome should be designed in a way that the deterioration of electrical performance in terms of mechanical strength and radio frequency(RF) can be minimized to protect the antenna. Electrical performance, in particular, is a critical factor that depends on the permittivity of the original materials and thus should be monitored during the manufacturing process along with other factors. This study set out to identify major factors that would affect permittivity during the manufacturing process of a radome through experiments and examine the impacts of permittivity on a radome's electrical performance through simulations.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.117-120
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• 2009

In this paper, a CR(Cognitive Radio) based on SDR(Software Defined Radio) is the technology combined a method selecting available frequency by recognizing surroundings with a learning algorithm continuously updating basic functions for communication and various environment parameters. Recently, as increasing demands with development of wireless communication service, CR is in the spotlight as technology using frequency resource efficiently. In order to apply CR system to the terminal and implement it, the research field to be preceded can be divided large as a hardware part and a software part. It can be also divided into RF processing and digital signal processing in the hardware part. In this paper, we look over preceding techniques required for applying CR system to the terminal, and research the forms of the terminal when they practically apply to the terminal.

• Journal of Biosystems Engineering
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• v.41 no.2
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• pp.108-115
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• 2016

Purpose: Radio frequency (RF) heating is a promising thawing method, but it frequently causes undesirable problems such as non-uniform heating. This can occur because of the food shape, component distribution, and initial temperature differences between food parts. In this study, RF heating was applied to the thawing of cylindrically shaped pork sirloin by changing the shape of electrodes and the surrounding temperature. Methods: Curved electrodes were utilized to increase the thawing uniformity of cylindrically shaped frozen meat. Pork sirloin in the shape of a half-circle column was frozen in a deep freezer at $-70^{\circ}C$ and then thawed by RF heating with flat and curved electrodes. In order to prevent fast defrosting of the food surface by heat transfer from air to the food, the temperature of the thawing chamber was varied by -5, -10, and $-20^{\circ}C$. The temperature values of the frozen pork sirloin during RF thawing were measured using fiber-optic thermo sensors. Results: After multiple applications of curved electrodes resembling the food shape, and a cooled chamber at $-20^{\circ}C$ the half-cylindrically shaped meat was thawed without surface burning, and the temperature values of each point were similarly increased. However, with the parallel electrode, the frozen meat was partially burned by RF heating and the temperature values of center were overheated. The uniform heating rate and heat transfer prevention from air to the food were crucial factors for RF thawing. In this study, these crucial factors were accomplished by using a curved electrode and lowering the chamber temperature. Conclusions: The curved shape of the electrode and the equipotential surface calculated from the modeling of the parallel capacitor showed the effect of uniform heating of cylindrically shaped frozen food. Moreover, the low chamber temperature was effective on the prevention of the surface burning during RF thawing.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2D
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• pp.295-302
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• 2011

Ubiquitous is an information communication environment which peoples could connect on network without being conscious of the network and computer condition at anytime and anywhere. Presently, advanced technology, digital cities and eco-friendly cities using Ubiquitous technology are being focused through out the world. As recent information industry and communication technology have developed remarkably, studies on intelligent structures and structural maintenance methods by combining a general idea of connecting all objects on network by interpolating computers which is called Ubiquitous Computing, and USN(Ubiquitous Sensor Network) are being attempted. In this paper, a basic experiment on penetration of RF(Radio Frequency) sensor nodes using an experimental sample setting concrete and reinforcing bar as variables is studied to estimate the possibility of applying wireless sensor networks in structures. The spring of reinforcing bars, concrete thickness, intensity of radio frequency were set up as variables, transmitting and receiving distance were checked vertically and horizontally. Moreover, Spectrum Analyzer was used for checking the magnitude of the frequency used in order to measure the reduction of radio wave exactly. The radio wave reduction was numerically analyzed, and the influence of the wavelength was analysed as well. As a result, the penetration depth in concrete without reinforcing bars was 45cm, and in reinforced concretes which reinforcing bars placed at spacing of 5cm and 15cm, the penetration depth were 37cm and 45cm each. No influence on radio wave penetration depth were found when the spacing of reinforcing bars in the reinforced concrete structures becomes over 15cm.

• Journal of the Semiconductor & Display Technology
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• v.4 no.2 s.11
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• pp.11-14
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• 2005

In plasma processing reactors, it is common practice to control plasma density and ion bombardment energy by manipulating excitation voltage and frequency. In this paper, a dually excited capacitively coupled rf plasma reactor is self-consistently simulated with a three moment model. Effects of phase differences between primary and secondary voltage waves, simultaneously modulated at various combinations of commensurate frequencies, on plasma properties are investigated. The simulation results show that plasma potential and density as well as primary self-dc bias are nearly unaffected by the phase lag between the primary and the secondary voltage waves. The results also show that, with the secondary frequency substantially lower than the primary frequency, secondary self·do bias remains constant regardless of the phase lag. As the secondary frequency approaches to the primary frequency, however, the secondary self-dc bias becomes greatly altered by the phase lag, and so does the ion bombardment energy at the secondary electrode. These results demonstrate that ion bombardment energy can be more carefully controlled through plasma simulation.