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Planar super-wideband loop antenna with asymmetric coplanar strip feed
Trinh-Van, Son,Kwon, Gina,Hwang, Keum Cheol IET 2016 Electronics letters Vol.52 No.2
<P>A planar super-wideband (SWB) antenna fed by an asymmetric coplanar strip is proposed, fabricated, and tested. The antenna consists of a hexagonal loop strip in which a signal strip is prolonged, curved, and shorted to a ground plane to facilitate SWB characteristics. In addition, by adding a boomerang-shaped strip to the ground plane, the effective electrical length is increased, thereby decreasing the lowest operating frequency. The simulated results show that the proposed antenna exhibits a -10 dB reflection bandwidth from 1.18 to 49.22 GHz corresponding to a ratio bandwidth of 41.7:1. The measured results of the fabricated antenna are also represented and compared with the simulated results. The antenna gain changes from 2.05 to 10.62 dBi within the measured frequency range.</P>
Waveguide Slot Array Antenna with a Hybrid-Phase Feed for Grating Lobe Reduction
Trinh-Van, Son,Song, Sung Chan,Seo, Seung-Hee,Hwang, Keum Cheol Hindawi Limited 2016 International journal of antennas and propagation Vol.2016 No.-
<P>The design of a 112-element millimeter-wave waveguide slot array antenna to reduce the grating lobe level is presented. A hybrid-phase feeding technique combining a cophase feed and an alternating-phase feed is applied to facilitate the suppression of grating lobes. In addition, a stepped feed waveguide and offset coupling slots aligned in a line are employed to realize a tapered aperture distribution. As a result, grating lobe suppression of 8.1 dB was achieved on the diagonal planes compared to a conventional alternating-phase-fed waveguide slot array antenna. A prototype of the proposed antenna was fabricated and measured. The measured results show that the proposed antenna exhibits a −15 dB reflection bandwidth of 3.4%and an average realized gain of 26.72 dBi within the measured frequency range. Good agreement between the simulated and measured radiation patterns is also observed.</P>
An Improvement of Closed-Form Formula for Mutual Impedance Computation
Son Trinh-Van,Keum Cheol Hwang,Joon-Young Park,Seon-Joo Kim,Jae-Ho Shin 한국전자파학회JEES 2013 Journal of Electromagnetic Engineering and Science Vol.13 No.4
In this paper, we present an improvement of a closed-form formula for mutual impedance computation. Depending on the center-to-center spacing between two rectangular microstrip patch antennas, the mutual impedance formula is separated into two parts. The formula based on synthetic asymptote and variable separation is utilized for spacings of more than 0.5λ0. When the spacing is less than 0.5λ0, an approximate formula is proposed to improve the computation for closely spaced elements. Simulation results are compared to computational results of mutual impedances and mutual coupling coefficients as functions of normalized center-to-center spacing in both E- and H-plane coupling configurations. A good agreement between simulation and computation is achieved.
Relaxor characteristics of PSLZT-BMT-based ferroelectric material ceramics
Nguyen Van Thinh,Le Dai Vuong,Do Viet On,Truong Van Chuong,Le Vu Truong Son,Trinh Ngoc Dat,Le Van Thanh Son,Vo Thanh Tung 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.3
(1-x)[(Pb0.94Sr0.05La0.01)(Zr0.54Ti0.46)0.9975O3]-x[Bi(Mn1/2Ti1/2)O3] (PSLZT-BMT) ferroelectric material ceramics with x in therange of 0-0.05 mol were successfully synthesized following the conventional solid-phase route. The materials were thoroughlyinvestigated to study their structural phase, microstructure, ferro-piezoelectric characteristics, and dielectric behavior. Theexperimental results show that the density of the samples decreased from 7.75 to 7.58 g/cm3, and the relative density decreasedin the range of 98.48%-96.28%. However, with increasing contents of BMT, the dielectric and ferroelectric properties ofPSLZT-BMT ceramics tend to decrease, specifically the maximum dielectric constant (εmax) of PSLZT-BMT decreased in therange of 23579-9991 and the residual polarization (Pr) decreases in the range of 22.54-7.87 μC/cm2 when the doping contentincreased in the range of 0.0-0.05 mol. The diffusivity values (γ) of the PSLZT-BMT material are 1.74, 1.78, 1.82, 1.84, 1.79,and 1.77 when the doping content x varies as 0.0, 0.01, 0.02, 0.03, 0.04, and 0.05 mol, respectively, which is characteristic ofrelaxor ferroelectric materials. Besides, the Tm, TB, TC-W, and C values depend on BMT concentration, and the trend decreases.
트린반손(Son Trinh-Van),권지나(Gina Kwon),황금철(Keum Cheol Hwang),박준영(Joon-Young Park),김선주(Seon-Joo Kim),김동환(Dong-Hwan Kim) 한국통신학회 2012 韓國通信學會論文誌 Vol.37 No.12(융합기술)
본 논문에서는 유전 알고리즘(genetic algorithm)을 이용하여 이중대역 다이폴 배열(dipole array) 안테나의 설계 및 최적화 문제에 대해서 고찰하였다. 다이폴로 구성된 이중대역, 개구면 공유형 선형 배열은 4 GHz와 9.5 GHz에서 동작하도록 설계하였다. 또한, 다이폴의 전류 분포는 모멘트 기법(method of moment)을 이용하여 계산되었으며, 계산 과정에서 다이폴 간 상호 결합(mutual coupling)을 고려하였다. 두 공진 주파수 대역에서 낮은 부엽 준위를 도출하기 위해서 비주기 다이폴 배열 설계에 유전 알고리즘을 적용하였고, 최적 설계된 이중대역 다이폴 배열 안테나는 4 GHz와 9.5 GHz에서 각각 -15.7 dB, -17 dB로 낮은 PSL 특성을 나타내었다. 또한, 이 결과를 상용 시뮬레이션 결과와 비교 분석하였다. In this research, optimization of a dual-band dipole array was performed using genetic algorithm. A non-uniform, aperture-shared linear array was configured with dipoles which resonate at 4 GHz and 9.5 GHz. The excited current distributions on dipoles were computed considering mutual coupling between dipole elements. The current distributions were also computed using method of moment (MoM). The optimization using genetic algorithm was performed to obtain the low sidelobe levels in two operating frequency band. The PSLs of the optimized array for 4 GHz and 9.5 GHz are -15.7 dB and -17 dB, respectively. Comparison between computed and simulated results are also discussed.
Two Human Cases of Echinococcus ortleppi Infection in the Lung and Heart in Vietnam
Nguyen Van De,Pham Ngoc Minh,Le Van Duyet,Nguyen Ngoc Bich,Trinh Nam Son,정봉광,채종일 대한기생충학ㆍ열대의학회 2020 The Korean Journal of Parasitology Vol.58 No.4
This is a report of 2 cases of human hydatidosis caused by Echinococcus ortleppi in Vietnam. The patients were a 12-year-old male (case 1) having a cyst of 10.0×9.0 cm size in the lung and a 50-year-old female with a 3.0×3.3 cm-sized cyst in the heart. Eosinophilia was 33.7% in the male and 45.8% in the female patient. C-reactive protein was increased to 16.5 mg/L in the male and 18.2 mg/L in the female. Both patients were positive for ELISA at OD=2.5 and 3.1, respectively. Echinococcus protoscolices were collected from the cysts by amniocentesis and surgery. The protoscolices were identified as E. ortleppi by morphology and analysis of mitochondrial NADH dehydrogenase 1 (nad1) gene sequence. Both patients were cured by surgical resection of the hydatid cyst combined with albendazole medication. The E. ortleppi infection in lung is the second report, and the other in the heart is the first in Vietnam.