다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Electromagnetic Metamaterials: Transmission Line Theory and Microwave Applications. By Christophe Caloz and Tatsuo Itoh.

Before the emergence of ultra-wideband (UWB) radios, widely used wireless communications were based on sinusoidal carriers, and impulse technologies were employed only in specific applications (e.g. radar). In 2002, the Federal Communication Commission (FCC) allowed unlicensed operation between 3.1–10.6 GHz for UWB communication, using a wideband signal format with a low EIRP level (−41.3dBm/MHz). UWB communication systems then emerged as an alternative to narrowband systems and significant effort in this area has been invested at the regulatory, commercial, and research levels.

IEEE Transactions on Microwave Theory and Techniques and Antennas and Propagation Announce a Joint Special Issue on Ultra-Wideband (UWB) Technology

Driver drowsiness and distraction are two main reasons for traffic accidents and the related financial losses. Therefore, researchers have been working for more than a decade on designing driver inattention monitoring systems. As a result, several detection techniques for the detection of both drowsiness and distraction have been proposed in the literature. Some of these techniques were successfully adopted and implemented by the leading car companies. This paper discusses and provides a comprehensive insight into the well-established techniques for driver inattention monitoring and introduces the use of most recent and futuristic solutions exploiting mobile technologies such as smartphones and wearable devices. Then, a proposal is made for the active of such systems into car-to-car communication to support vehicular ad hoc network's (VANET's) primary aim of safe driving. We call this approach the dissemination of driver behavior via C2C communication. Throughout this paper, the most remarkable studies of the last five years were examined thoroughly in order to reveal the recent driver monitoring techniques and demonstrate the basic pros and cons. In addition, the studies were categorized into two groups: driver drowsiness and distraction. Then, research on the driver drowsiness was further divided into two main subgroups based on the exploitation of either visual features or nonvisual features. A comprehensive compilation, including used features, classification methods, accuracy rates, system parameters, and environmental details, was represented as tables to highlight the (dis)advantages and/or limitations of the aforementioned categories. A similar approach was also taken for the methods used for the detection of driver distraction.

Driver Behavior Analysis for Safe Driving: A Survey

A novel approach for realization of a feeding network allowing for achieving dual-circular polarization in the slot-coupled microstrip antenna lattice has been proposed. The presented feeding network is an eight-port composed of four 3\mathchar"702DdB/90
 °
 directional couplers, and when appropriately integrated with the four-port series-fed antenna lattice ensures a full symmetry of the antenna layout and produces simultaneously right-handed and left-handed circular polarization. The proposed low-profile, low-cost solution can be easily integrated with the antenna lattice, and it allows for reduction of the introduced dissipation losses comparing to the known solutions, i.e., external feeding networks such as Butler matrices or power combiner/divider networks connected via coaxial cables. The proposed concept has been examined by measurements of the manufactured feeding network integrated with the previously developed antenna lattice operating at 5.4 GHz.

Compact Integrated Feeding Network for Excitation of Dual-Circular Polarization in Series-Fed Antenna Lattice

An 8 × 4 microstrip antenna array operating within 24 GHz frequency range has been shown. The presented antenna features two beams: a broadside beam and a dual beam. It allows for detection of targets in two different ranges and at two different angular positions. Additionally, the antenna can be used for the direction finding. The proposed antenna array uses `through-element' series feeding technique for dissipation losses reduction as well as the stacked laminate structure to separate the radiating elements and the feeding network, which allows for achieving satisfactory radiation patterns in a wide frequency range.

Multi-beam and multi-range antenna array for 24 GHz radar applications

A concept of scalable antenna arrays with an even number of radiating elements and nonuniform element spacing has been proposed. It has been shown that the proposed arrays can be fed with a frequency-selective network based on a well-known directional filter and with such a network the beamwidth can be kept constant across one frequency octave. The appropriate adjustment of coupled-line sections in such a directional filter allows for flexible selection of transmission coefficients between two outputs, and therefore, can be used for gradual switching of the signals between radiating elements. The proposed frequency-selective feeding network has been applied in a six-element antenna array operating in 1.75–3.5 GHz frequency range in which constant beamwidth around 16° has been achieved.

Frequency-Selective Feeding Network Based on Directional Filter for Constant-Beamwidth Scalable Antenna Arrays

An efficient modeling method for folded coupled inductors for application in quasi-lumped directional couplers designed in both symmetric and asymmetric structures has been proposed. The presented model takes into account the deteriorative effects which occur when coupled inductors realized as electrically short coupled-lines matched to the high impedance standard are folded into, for example, meander or spiral pattern. The deteriorative influence of coupled-lines' folding on the performance of the resulting directional coupler has been modeled as additional lumped inductors and capacitors on the schematic diagram of a quasi-lumped directional coupler's subsection. Moreover, it has been shown that this deteriorative influence can be substantially minimized when values of lumped elements constituting the directional coupler are appropriately changed. The proposed design procedure has been experimentally verified by measurements of two 3-dB single-section directional couplers designed in symmetric and asymmetric structures as quasi-lumped couplers with folded coupled inductors. The measurement results show a good agreement with both circuit and electromagnetic analysis which proves the correctness and usefulness of the presented methods. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:1–9, 2015.

Modeling and performance improvement of folded coupled lines in miniaturized Quasi‐lumped directional couplers

A newly developed, low cost FMCW radar system for industrial applications operating in K band has been presented. The radar features interferometric capability, which gives it sub-millimeter accuracy in distance variation measurement. Moreover, the presented radar has fully embedded signal processing with real time monitoring capability, thus making the presented sensor suitable for fully autonomous operation. The radar performance has been experimentally verified. Mean accuracy better than 30 μm has been achieved in displacement measurement test. The obtained results in terms of high accuracy and high measurement repetition rate prove the radar capable of meeting rigorous requirements of applications like structural health monitoring or industrial process control.

Slawomir Gruszczynski

Papers

Compact Integrated Feeding Network for Excitation of Dual-Circular Polarization in Series-Fed Antenna Lattice

Multi-beam and multi-range antenna array for 24 GHz radar applications

Frequency-Selective Feeding Network Based on Directional Filter for Constant-Beamwidth Scalable Antenna Arrays

Modeling and performance improvement of folded coupled lines in miniaturized Quasi‐lumped directional couplers

K-band FMCW radar module with interferometic capability for industrial applications