• ETRI Journal
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• v.32 no.1
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• pp.1-10
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• 2010

In this paper, we present a fast Fourier transform (FFT) processor with four parallel data paths for multiband orthogonal frequency-division multiplexing ultra-wideband systems. The proposed 128-point FFT processor employs both a modified radix-$2^4$ algorithm and a radix-$2^3$ algorithm to significantly reduce the numbers of complex constant multipliers and complex booth multipliers. It also employs substructure-sharing multiplication units instead of constant multipliers to efficiently conduct multiplication operations with only addition and shift operations. The proposed FFT processor is implemented and tested using 0.18 ${\mu}m$ CMOS technology with a supply voltage of 1.8 V. The hardware- efficient 128-point FFT processor with four data streams can support a data processing rate of up to 1 Gsample/s while consuming 112 mW. The implementation results show that the proposed 128-point mixed-radix FFT architecture significantly reduces the hardware cost and power consumption in comparison to existing 128-point FFT architectures.

• ETRI Journal
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• v.31 no.2
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• pp.225-227
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• 2009

A new planar metamaterial (MTM) with simultaneous negative values of permittivity (${\varepsilon}$) and permeability (${\mu}$) is proposed. Our MTM is composed of two identical copper patterns etched on both sides of dielectric laminate, which is very thin and easy to fabricate. Unlike conventional MTMs, the proposed structure shows a negative refractive index (NRI) behavior with respect to a normally incident wave. To explain the underlying principle of the NRI characteristics, an equivalent resonant circuit model based on surface current density distribution is investigated. An eigenmode analysis and a three-dimensional wave simulation for the stacked MTM prism are also performed to verify the existence of negative refraction. The experimental results from the transmission and reflection measurement ensure the validity of our design approach and show good agreement with the theoretically predicted effective medium parameters.

• ETRI Journal
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• v.31 no.1
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• pp.68-70
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• 2009

In this letter, a parametric analysis of the Fresnel-field antenna measurement method is performed for a square aperture. As a result, the optimum number of Fresnel fields for one far-field point is guided as $M_{opt}=N_{opt}=D^2/{\lambda}R+5$, where D is the antenna diameter, ${\lambda}$ is the wavelength, and R is the distance between the source antenna and the antenna under test. For the aperture size 5 ${\leq}$ $L_x/{\lambda}$ ${\leq}$ 20, the tolerable distances for gain errors of 0.5 dB and 0.2 dB can be guided as $R_{0.5\;dB}$ ${\approx}$ $1.2Lx/{\lambda}$ and $R_{0.2\;dB}$ ${\approx}$ $2.0L_x/{\lambda}$, where $L_x$ is the lateral length of the square aperture. The tolerable distances for 20 ${\leq}$ $L_x/{\lambda}$ ${\leq}$ 200 are also proposed. This measurement guideline can be fully utilized when performing the Fresnel-field antenna measurement method.

• ETRI Journal
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• v.31 no.5
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• pp.631-633
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• 2009

We introduce an improved Ethernet ring protection method, selective filtering database (FDB) advertisement, to minimize traffic overshoot in the event of a failure or recovery. On the protection switching event, the proposed method makes all ring nodes perform an FDB flush except the FDB entries associated with their client subnets. Then, ring nodes rapidly exchange their client MAC address lists so that their FDBs are immediately updated by indirect MAC address learning. The proposed scheme guarantees fast and reliable protection switching over the standard scheme.

• ETRI Journal
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• v.30 no.5
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• pp.735-737
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• 2008

We propose a novel spatial multi-band-stop filter using modified multiple loop array elements to block electromagnetic waves or signals of mobile phones in public facilities. It operates at the following frequency bands: Korean cellular (824 MHz to 894 MHz), Personal Communication Service (PCS) (1.75 GHz to 1.87 GHz), and IMT-2000 (1.92 GHz to 2.17 GHz). Two frequency selective surfaces with modified multiple-loop elements are printed on the top and bottom of a pair-glass pane, which is a pair of glass panes with an air gap between them. A modified multiple-loop element with a meander line is used to make the size of the filter compact. The simulated and measured results show good agreement, which confirms the usefulness of the proposed tri-band spatial filter.

• ETRI Journal
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• v.34 no.1
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• pp.110-113
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• 2012

We propose a very-low-complexity lattice-reduction (LR) algorithm for multi-input multi-output detection in time-varying channels. The proposed scheme reduces the complexity by performing LR in a block-wise manner. The proposed scheme takes advantage of the temporal correlation of the channel matrices in a block and its impact on the lattice transformation matrices during the LR process. From this, the proposed scheme can skip a number of redundant LR processes for consecutive channel matrices and performs a single LR in a block. As the Doppler frequency decreases, the complexity reduction efficiency becomes more significant.

• Electronics and Telecommunications Trends
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• v.19 no.2 s.86
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• pp.101-110
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• 2004

본 연구에서는 통신. 방송 융합의 개념과 통신. 방송 융합 서비스의 현황을 알아보고 통신. 방송 융합 서비스관련 국내외의 분류 기준을 살펴보고자 한다. 또한 대표적인 통신. 방송 융합형 서비스인 위성 DMB 서비스를 실제로 연구에 적용하여, 국내 위성 DMB 서비스 관련 정책환경 분석과 더불어 위성 DMB 서비스와 유사서비스와의 비교를 통해 통신. 방송 융합서비스가 보유하고 있는 차별적 성격을 도출하는 한편, 그 시사점을 제시하고자 한다.

• Journal of Broadcast Engineering
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• v.15 no.2
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• pp.192-204
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• 2010

As illegal distribution of the terrestial DTV broadcast program occurs very frequently in on-line, the needs to protect broadcast program have increased. In this paper, a new approach to implement a system for terrestial DTV broadcast program protection based on program protection information(PPI) is proposed. In our approach, the broadcast program is recorded with encryption according to redistribution condition of the PPI and packaged into a file with key information and PPI together. And we also define a set of domain protocol for supporting user fair-use of broadcast program. In the proposed system, copy control can also be provided by process of home domain management. Implementation results show that our system can protect broadcast programs with efficiency and can support conditional distribution within home domain in order to satisfy user fair-use.

• ETRI Journal
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• v.31 no.3
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• pp.321-323
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• 2009

A wideband beamforming algorithm for estimating the azimuth angle, elevation angle, velocity, and range using a planar phased radar array with antenna switching is proposed. It uses the time-variant steering vector model. Simulation results illustrating the performance of the proposed beamformer are presented.

• Electronics and Telecommunications Trends
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• v.39 no.2
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• pp.43-53
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• 2024

The media environment is rapidly evolving to be tailored to viewers using personal mobile devices in accordance with technological evolution and changes in social structures. Broadcast media technology is also advancing to enable new services, including data casting, in various reception environments beyond the existing fixed environment and one-way audio/video content services. In addition, technologies to increase the transmission capacity to accommodate next-generation large-capacity media content as well as communication network utilization and convergence technologies are being developed to facilitate interactive services and expand the broadcasting coverage. We discuss the current status and future prospects in broadcasting technology for terrestrial and mobile communication systems and analyze broadcasting technology elements for upcoming media environments relying on generative artificial intelligence.