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A Model-Based Analysis of Secure Video Transmission Based on IPSec and IPv4
Quang-Dao Van,Anne Wei,Benoît Geller,Gérard Dupeyrat 한국전자통신연구원 2005 ETRI Journal Vol.27 No.2
A promising solution to protect wired Internet networks is to use the Secure Internet Protocol (IPSec); however, this has some drawbacks, particularly on the quality of service (QoS). This paper aims at evaluating the video traffic QoS in terms of end-to-end delay and packet loss rate. Based on some basic assumptions, our analysis shows that the performance with IPSec is rapidly inferior to the IPv4 performance. We thus suggest adding some QoS parameters into IPSec in order to achieve a compromise between QoS and security.
Study on the vibration behavior of a G/T 3-ton class composite fishing boat hybrid propulsion system
Quang Dao Vuong,김영민,이지웅 한국마린엔지니어링학회 2022 한국마린엔지니어링학회지 Vol.46 No.6
In recent years, eco-friendly ships have been widely used to optimize energy efficiency and prevent air pollution. Composite materials can reduce the weight of vessels, reduce maintenance costs and time, and maximize vessel life. In addition, if a ship is equipped with a hybrid propulsion system, its prime movers can be alternated, improving its flexibility in various maneuvering condi-tions. However, the vibration behavior of the ship should be confirmed when new materials are used for the ship hull and for new hybrid transmission configurations. In this study, the performance of a hybrid propulsion system for a 3-ton G/T-class composite fishing boat was evaluated through experiments during a sea trial. The results revealed that torsional vibration exhibits resonance in the propeller speed range of 300 to 350 rpm. The level of resonance is not sufficiently high to damage the shaft, but it may cause the electromagnetic clutch to slip. Thus, propeller efficiency is not maximized. Additionally, this results in a high level of structural vibra-tion. The propulsion system design must be modified to improve the vibration behavior of the ship.
Role of Atomic and Molecular Nitrogen in Carbon Nanotube Formation
Dao Quang Duy,김현석,Dang Mo Yoon,Jung Woong Ha,Kang Jea Lee,황용규,Bach Thanh Cong,이충훈 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.4
We have investigated the pretreatment effects of nitrogen on the length and the alignment of carbon nanotubes (CNTs) grown on a Ni catalyst by using dc-plasma enhanced chemical vapor deposition system. The surface of the Ni catalyst was pretreated with a mixture of NH3 and N2, instead of pure NH3 and the length of the CNTs has changed from 1.6 um to 400 nm as the NH3/N2 flow rate ratio was decreased. We showed that the length and the alignment of the CNTs could be controlled by changing the NH3/N2 flow rate ratio. The fabricated CNTs were further evaluated by using their Raman spectra. The nitrogen concentration on the surface of the Ni catalyst after the pre-treatment was analyzed by using X-ray photoelectron spectroscopy and the physical structure of CNTs was analyzed using scanning electron microscopy and high resolution transmission electron microscope. We suggest that the N2 adsorption on the surface of Ni changes the carbon atom diffusion during the CNT growth and that the physical structures of CNTs are drastically changed We have investigated the pretreatment effects of nitrogen on the length and the alignment of carbon nanotubes (CNTs) grown on a Ni catalyst by using dc-plasma enhanced chemical vapor deposition system. The surface of the Ni catalyst was pretreated with a mixture of NH3 and N2, instead of pure NH3 and the length of the CNTs has changed from 1.6 um to 400 nm as the NH3/N2 flow rate ratio was decreased. We showed that the length and the alignment of the CNTs could be controlled by changing the NH3/N2 flow rate ratio. The fabricated CNTs were further evaluated by using their Raman spectra. The nitrogen concentration on the surface of the Ni catalyst after the pre-treatment was analyzed by using X-ray photoelectron spectroscopy and the physical structure of CNTs was analyzed using scanning electron microscopy and high resolution transmission electron microscope. We suggest that the N2 adsorption on the surface of Ni changes the carbon atom diffusion during the CNT growth and that the physical structures of CNTs are drastically changed
Vu, Quang Dao,Nguyen, Thanh Binh,Chung, Sun-Tae Korea Multimedia Society 2017 멀티미디어학회논문지 Vol.20 No.6
In this paper, we propose a simple online multiple object (human) tracking method, LKDeep (Lucas-Kanade feature and Detection based Simple Online Multiple Object Tracker), which can run in fast online enough on CPU core only with acceptable tracking performance for embedded surveillance purpose. The proposed LKDeep is a pragmatic hybrid approach which tracks multiple objects (humans) mainly based on LK features but is compensated by detection on periodic times or on necessity times. Compared to other state-of-the-art multiple object tracking methods based on 'Tracking-By-Detection (TBD)' approach, the proposed LKDeep is faster since it does not have to detect object on every frame and it utilizes simple association rule, but it shows a good object tracking performance. Through experiments in comparison with other multiple object tracking (MOT) methods using the public DPM detector among online state-of-the-art MOT methods reported in MOT challenge [1], it is shown that the proposed simple online MOT method, LKDeep runs faster but with good tracking performance for surveillance purpose. It is further observed through single object tracking (SOT) visual tracker benchmark experiment [2] that LKDeep with an optimized deep learning detector can run in online fast with comparable tracking performance to other state-of-the-art SOT methods.
Pham, Duong Quang,Ba, Duong Thi,Dao, Nga Thu,Choi, Gyung Ja,Vu, Thuy Thu,Kim, Jin-Cheol,Giang, Thi Phuong Ly,Vu, Hoang Dinh,Le Dang, Quang Elsevier 2017 INDUSTRIAL CROPS AND PRODUCTS Vol.108 No.-
<P><B>Abstract</B></P> <P>The antimicrobial efficacies of extracts and constituents fractionated from <I>Rheum tanguticum</I> rhizomes were evaluated by using <I>in vitro</I> and <I>in vivo</I> bioassay against seven phytopathogenic fungi and ten pathogenic bacteria, respectively. Dichloromethane and ethyl acetate soluble extracts derived from <I>R. tanguticum</I> rhizomes effectively controlled plant diseases caused by five fungi <I>Magnaporthe oryzae</I>, <I>Blumeria graminis</I> f. sp<I>. hordei, Colletotrichum coccodes, Phytophthora infestans,</I> and <I>Puccinia recondita</I> in <I>in vivo</I> whole plant bioassay. In addition, these extracts showed strong inhibitory activity against the bacterial growth of <I>Acidovorax avenae</I> subsp. <I>cattlyae</I> (Aac), <I>Clavibacter michiganensis</I> subsp. <I>michiganensis</I>, <I>Xanthomonas arboricola</I> pv. <I>pruni</I> (Xap), and <I>Pseudomonas syringae</I> pv. <I>actinidiae</I> (Psa), with MIC values ranging from 125 to 250μg/mL. The active extracts of <I>R. tanguticum</I> rhizomes were fractionated by using various and repeated chromatographic techniques to yield seven constituents that included three anthraquinones and four stilbenes. Notably, at concentrations ranging from 75 to 300μg/mL, physcion (<B>DH03</B>) and chrysophanol (<B>DH04</B>) were significantly effective in suppressing the development of barley powdery mildew (BPM) caused by <I>B. graminis</I> f. sp. <I>hordei,</I> with control values from 80 to 96.7%. Moreover, stilbenes rhapontigenin (<B>DH02</B>) and desoxyrhapontigenin (<B>DH05</B>) had a broad spectrum and potent activity against phytopathogenic bacteria; <B>DH05</B> effectively inhibited the bacterial growth of Aac, <I>Burkholderia glumae</I> and Psa at MICs ranging from 38 to 150μg/mL. In this paper, we report their antibacterial activity for the first time. The botanical materials containing anthraquinones and stilbenes were active against both phytopathogenic fungi and bacteria. These results suggested that <I>R. tanguticum</I> rhizomes could be used as a new source of antimicrobial substances for developing a botanical fungicide and bactericide to control plant diseases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>R. tanguticum</I> extracts exhibited activity against phytopathogenic fungi and bacteria. </LI> <LI> Seven anthraquinones and stilbenes from <I>R. tanguticum</I> were isolated and identified. </LI> <LI> <I>In vivo</I> antifungal activity of botanicals was evaluated by the whole plant bioassay. </LI> <LI> The isolated stilbenes effectively inhibited the growth of phytopathogenic bacteria. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>