• Journal of Communications and Networks
• /
• v.11 no.6
• /
• pp.544-555
• /
• 2009

This work continues a trend of developments aimed at exploiting the physical layer of the open systems interconnection (OSI) model to enhance wireless network security. The goal is to augment activity occurring across other OSI layers and provide improved safeguards against unauthorized access. Relative to intrusion detection and anti-spoofing, this paper provides details for a proof-of-concept investigation involving "air monitor" applications where physical equipment constraints are not overly restrictive. In this case, RF fingerprinting is emerging as a viable security measure for providing device-specific identification (manufacturer, model, and/or serial number). RF fingerprint features can be extracted from various regions of collected bursts, the detection of which has been extensively researched. Given reliable burst detection, the near-term challenge is to find robust fingerprint features to improve device distinguishability. This is addressed here using wavelet domain (WD) RF fingerprinting based on dual-tree complex wavelet transform (DT-$\mathbb{C}WT$) features extracted from the non-transient preamble response of OFDM-based 802.11a signals. Intra-manufacturer classification performance is evaluated using four like-model Cisco devices with dissimilar serial numbers. WD fingerprinting effectiveness is demonstrated using Fisher-based multiple discriminant analysis (MDA) with maximum likelihood (ML) classification. The effects of varying channel SNR, burst detection error and dissimilar SNRs for MDA/ML training and classification are considered. Relative to time domain (TD) RF fingerprinting, WD fingerprinting with DT-$\mathbb{C}WT$ features emerged as the superior alternative for all scenarios at SNRs below 20 dB while achieving performance gains of up to 8 dB at 80% classification accuracy.

• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.1860-1862
• /
• 2004

It is widely known that the ultra high frequency (UHF) method that detects the electromagnetic wave of the PD pulses in the gas insulated space is one of the most competitive methods for its high sensitivity. From the above point of view, this paper describes the characteristics of GIS PD signals measured with ultra wide band (UWB) GIS PD detecting system in which PD signals are detected into the dual UHF band. The UWB PD detection system consists of the UWB UHF coupler, the UWB low noise amplifier (LNA) and the oscilloscope. The dual bands for PD signals are 0.5-2GHz(full band) and 1-2GHz(high band). As results, it was found that the partial discharges of each defect have their own characteristic pattern and the ratio of High band to Full band increases with gas pressure.

• Proceedings of the KIEE Conference
• /
• 2006.10c
• /
• pp.269-272
• /
• 2006

In this paper we describe the design of a Dual Power Controller(DPC) for Power Control System(PCS) in Nuclear Power Plant. The PCS also provides information regarding rod motion, rod position, and status of the Rod Control System. It has Hot/Stand-by type, and also has the function of fault detection for controller itself and power modules. We have implemented the various functions with the dual Power Controller. Due to the developed DPC, we are assured that the commmecial use by this controller be made before long.

• Proceedings of the KIEE Conference
• /
• 2004.07d
• /
• pp.2370-2373
• /
• 2004

In this paper we describe the design of a Dual-Redundant Power Controller(DRPC) for Control Rod Control System(CRCS). The CRCS also provides information regarding rod motion, rod position, and status of the Rod Control System. It has Hot/Stand-by type, and also has the function of fault detection for controller itself and power modules. We have implemented the various functions with the dual-redundant Power Controller. Due to the developed DRPC, we are assured that the commmecial use by this controller be made before long.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.04a
• /
• pp.251-254
• /
• 2003

In recent years, shearogrpahy has significantly improved capabilities In the areas of unbend and separation detection in tires. Although shearography has many advantages fur qualitative evaluation, the technique remains the problem of quantitative analysis of inside defects, because shearography needs several effective factors including the amount of shearing, shearine direction and induced load, which exist as barrier for the quantitative analysis of inside defects. Since the factors are highly dependent on inspectors skill and also affect the in-situ workability. The factors were optimized and the size of cracks inside of pipeline and tire has been quantitatively determined.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.32A no.4
• /
• pp.24-31
• /
• 1995

In this paper, the dual-mode burst-error-correcting decoding algorithm is adapted to the multiple trellis-coded .pi./4 shift QPSK in order to achieve the improvement of bit error rate (BER) performance over fading channels. The dual-mode adaptive decoder which combines maximum likelihood decoding with a burst detection scheme usually operates as a Viterbi decoder and switches to time diversity error recovery whenever an uncorrectable error pattern is identified. Rayleigh fading channels and Rician fading channels having the Rician parameter K=5dB are used in computer simulation, and the simulation results are compared with those of interleaving techniques. It is shown that under the constraint of the fixed overall memory quantity, the dual-mode adaptive decoding scheme gains an advantage in the BER performance with respect to interleaving strategies.

• Proceedings of the KIEE Conference
• /
• 2004.11d
• /
• pp.63-66
• /
• 2004

It is widely known that the ultra high frequency (UHF) method that detects the electromagnetic wave of the PD pulses in the gas insulated space is one of the most competitive methods for its high sensitivity. From the above point of view, this paper describes the characteristics of GIS PD signals measured with ultra wide band (UWB) GIS PD defecting system in which PD signals are defected into the dual UHF band. Thc UWB PD detection system consists of the UWB UHF coupler, the UWB low noise amplifier (LNA) and the oscilloscope. The dual bands for PD signals are 0.5-2GHz(full band) and 1-2GHz(high band). As results, it was found that the partial discharges of each defect have their own characteristic pattern and the ratio of High hand to Full band increases with gas pressure.

• ETRI Journal
• /
• v.34 no.3
• /
• pp.466-469
• /
• 2012

In this letter, we propose a dual autostereoscopic display platform employing a natural interaction method, which will be useful for sharing visual data with users. To provide 3D visualization of a model to users who collaborate with each other, a beamsplitter is used with a pair of autostereoscopic displays, providing a visual illusion of a floating 3D image. To interact with the virtual object, we track the user's hands with a depth camera. The gesture recognition technique we use operates without any initialization process, such as specific poses or gestures, and supports several commands to control virtual objects by gesture recognition. Experiment results show that our system performs well in visualizing 3D models in real-time and handling them under unconstrained conditions, such as complicated backgrounds or a user wearing short sleeves.

• Proceedings of the KIEE Conference
• /
• 2004.05b
• /
• pp.136-139
• /
• 2004

It is widely known that the ultra high frequency (UHF) method that detects the electromagnetic wave of the PD pulses in the gas insulated space is one of the most competitive methods for its high sensitivity. From the above point of view, this paper describes the propagation characteristics of GIS PD signals measured with ultra wide band (UWB) GIS PD detecting system in which PD signals are detected into the dual UHF band. The UWB PD detection system consists of the UWB UHF coupler, the UWB low noise amplifier (LNA) and the oscilloscope. The dual bands for PD signals are 0.5-2GHz(full band) and 1-2GHz(high band). As results, propagation characteristics of GIS PD signals were measured in the mock-up GIS bus and it was found that the propagation characteristics of the high band showed a better result in accordance with the infernal configuration of the GIS bus than those of the full band.

• Korean Chemical Engineering Research
• /
• v.61 no.3
• /
• pp.463-471
• /
• 2023

Nitrogen-rich carbon dots (NDots) were synthesized by using uric acid as carbon and nitrogen sources. The as-synthesized NDots showed strong dual emissions at 420 nm and 510 nm with excitation at 350 nm and 460 nm, respectively. The physicochemical analyses such as X-ray photoelectron spectroscopy, Transmission electron microscopy and Fourier transform infrared spectroscopy were used to analyze the chemical, physical and morphological structures of NDots. The as-synthesized NDots exhibited wide linear range (0-100 µM) and very low detection limit (124 nM) in Ag⁺ ion sensing. In addition, Ag⁺ saturated NDots could be used as an EDTA sensor by the EDTA induced PL recovery.