• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2C
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• pp.187-198
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• 2004

In this paper, we analyze the performance of BPM (Bi-Phase Modulation) UWB (Ultra Wide Band) multiple access system using PN (Pseudo Noise) code based time hopping sequence in indoor wireless channels. In particular, we compare BPM UWB multiple access system with PPM (Pulse Position Modulation) UWB multiple access system in terms of signalling and demodulation schemes. Moreover, we analytically evaluate the performance of these UWB systems by deriving the bit error rate expressions under the assumption that pulse energy and data transmission rate are identical for both systems. Simulation results in additive white Gaussian noise and realistic indoor multipath wireless channels show that the performance of BPM scheme is approximately 1 dB better than that of PPM scheme. However, the performance discrepancy becomes negligible as the number of users increases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11C
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• pp.1498-1509
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• 2004

In this paper, we evaluate the performance of a noncoherent OOK (On-Off Keying) UWB (Ultra Wide Band) system based on power detection with noise power calibration and noise power windowing for ubiquitous sensor network applications in typical indoor wireless channels. Utilizing noise power calibration and noise power windowing, the current noise information can be initially or adaptively provided to determine suitable detection threshold value for signal demodulation. Simulation results show that the noncoherent OOK UWB system using noise power calibration achieves good BER (Bit Error Rate) performance which is favorably comparable to that of the system using the ideal adaptive threshold, while maintaining simple receiver structure. However, despite the serious loss of the data transmission rate, the performance improvement by noise power windowing is not so remarkable. furthermore, these performance results are similarly maintained in BEE 802.15 Task Group 3a UWB indoor channel model, and it is also revealed that the BER performance can be significantly improved by increasing the pulse repetition rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.657-661
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• 2019

The automobile industry is representative industry of complex characteristics, which employing 10 million people, the largest manufacturing industry over $1 trillion in sales and assembling with 20,000 parts to make complete automobile and automobile assembly processes have a lower automation rate than other processes, which is labor intensive processes of assembling to painted body with 3,000 components such as seats, built-in, instrument panel, glass, engine, transmission units. However, the current assembly process does not have real-time monitoring. If a tool position tracking system is adapted to assembly process for directing consistent work order and checking for missing work, the productivity and quality improvement of the assembly process can be achieved by preemptively preventing possible defects in the assembly process. So, this paper aims to develop a Tool Position tracking system using UWB(Ultra Wide Band) with trilateration and proves their effectiveness for real-time monitoring of automotive assembly process.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.679-682
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• 2008

High interest for the wireless network is going on the research to apply the related technologies in one's real life. Among these wireless network technologies, local area wireless network, Binary CDMA(Code Division Multiple Access), is the method transferring the data by using RF band based on 2.4Ghz. Binary CDMA has longer transmission distance than Bluetooth. Also, it is of benefit to an inexpensive price because the circuit is simple as compared with being similar to the performance of the existing CDMA. Though Binary CDMA has these benefits, one problem is a frequency overlap, and anther problem is to generate the sections with the shorter distance. To solve these problems, We propose the clustering method that can cover wide area.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9A
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• pp.909-916
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• 2008

In this paper, we propose and analyze M-ary pulse order time hopping multiple access ultra wideband (PO-THMA UWB) system using modified Hermite polynomial (MHP). The MHP pulses have a mutually orthogonal property between different ordered pulses and that property makes simultaneous transmission at the same time slot regardless of collision in the THMA-UWB system. Therefore, we derive the cross-correlation furlction of MHP pulses and analyze the BER of the proposed system and show that the BER performance and the transmission capacity are improved dramatically when compared with those of conventional THMA-UWB system.

• Journal of KIISE:Information Networking
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• v.36 no.5
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• pp.383-388
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• 2009

In this paper, we focus on the retransmission following transmission failure in impulse radio ultra wideband (IR-UWB). The reasons of transmission failure are classified and a new 'selfish' retransmission protocol is proposed because time hopping can support multiple transmissions at the same time. Selfish retransmission protocol retransmits packets immediately without any kind of timeout or channel observation. Simulation results show that the proposed protocol improves throughput up to 50% and decreases retransmission delay also up to 70%, compared to a conventional retransmission system in IR-UWB.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.2
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• pp.155-160
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• 2024

The polarization-selective beam splitter grating can be widely used in numerous optical information processing systems. In this paper, to design a high-efficiency plasma polarization beam splitter (PBS), the structure composed of an Ag metal layer in Littrow mounting is implemented. To achieve high diffraction efficiency in the transmitted 0th-order TE polarization and the reflected 0th-order TM polarization, the grating depth and grating ratio of presented PBS is optimized by using rigorous Modal Transmission-Line Theory. From the optimized results, PBS has advantages of wide band properties for incident wavelength and angle, and the efficiency is higher than 95% for both TE and TM polarization. Therefore, this highly efficient PBS wideband grating with high extinction ratio can be used as an excellent optical diffraction device.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.2
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• pp.46-53
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• 2007

Extension of the mobile communication and the rapidly developing services connected with wireless multimedia(W-CDMA, DMB, Wibro, and so on) need great many base station transceiver systems, antennas, and many signal transmission line to embody these services. The min communication appliances system is exposed always in danger of transient overvoltage by direct stroke or induced lightning surge flowing in through antenna because the antenna of base station transceiver system or relay equipment is combined with expensive communication network equipments through signal transmission line. Now, gas discharge tube(GDT) or narrow band stub arrestor which is used by the surge protector for communication use is exposing limitations as for lightning surge protective means of the communication facility with high speed and wide frequency band. Therefore, for improving performance of surge arrestor, we applied ceramic filter which can reduce lightning surge invading from antenna effectively, and proved that ceramic filter is effective in residual voltage reduction through the experimental research.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.87-93
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• 2008

This paper describes implementation of the 5.0GHz RF frequency synthesizer with $0.18{\mu}m$ silicon CMOS technology being used as an application of the IEEE802.15.4 USN sensor node transceiver modules. To get good performance of speed and noise, design of the each module like VCO, prescaler, 1/N divider, fractional divider with ${\Sigma}-{\Delta}$ modulator, and common circuits of the PLL has been optimized. Especially to get good performance of speed, power consumption, and wide tuning range, N-P MOS core structure has been used in design of the VCO. The chip area including pads for testing is $1.1*0.7mm^2$, and the chip area only core for IP in SoC is $1.0*0.4mm^2$. Through comparing and analysing of the designed two kind of the frequency synthesizer, we can conclude that if we improve a litter characteristics there is no problem to use their as IPs.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.299-307
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• 2015

Reduction in pollution performance of polymeric insulators, aged due to water absorption stress and thermal stress, is a major threat to the reliable operation of power transmission and distribution system. Formation of partial discharges on the surface of wet polluted insulator plays a major role in determining the life time and pollution performance of outdoor polymeric insulators. However, reports on partial discharge characteristics of water absorption stress aged and thermal aged polymeric insulators are scanty. This paper discusses the pollution performance characteristics of accelerated aged polymeric insulators using the advanced ultra wide band PD signal measurement and analysis. Laboratory experiments on accelerated aged polymeric insulators were carried out as per IEC 60507 under AC voltage, at different humidity and contamination levels using NaCl as a contaminant. PRPD pattern and Time-Frequency map analysis of PD signals were carried out. From the results, it can be speculated that PD analysis is a well suited technique to understand the pollution performance of aged polymeric insulators.