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Quoc-Tuan Vien,Dao-Tan-Hoang Nguyen,Le-Nam Tran,Een-Kee Hong 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7
This paper proposes a new distributed space-time block code (DSTBC) over frequency selective fading channels in amplify-and-forward (AF) turbo-coded cooperative wireless relay networks with hybrid automatic repeat request (HARQ) combining schemes. The proposed DSTBC and HARQ schemes are designed to achieve spatial diversity gain and low decoding complexity. These goals are obtained by precoding the received signal at the relay to form the conventional space-time block codes. In addition, the coding gain is combined with the diversity gain to enhance the performance of DSTBC by adding turbo coding at the source and iterative decoding at the destination. Together with turbo coding, two fundamental HARQ combining schemes are considered in our design, including Chase combining (CC) and incremental redundancy (IR).
Distributed Space-Time Block Code over Mixed Rayleigh and Rician Frequency-Selective Fading Channels
Vien, Quoc-Tuan,Tran, Le-Nam,Hong, Een-Kee Hindawi Publishing Corporation 2010 Eurasip Journal on Wireless Communications and Net Vol.2010 No.-
<P>This paper proposes a new distributed space-time block code (DSTBC) over frequency-selective fading channels for two-hop amplify and forward relay networks, consisting of a source node (S), two relay nodes (R1 and R2), and a destination node (D). The proposed DSTBC is designed to achieve maximal spatial diversity gain and decoupling detection of data blocks with a low-complexity receiver. To achieve these two goals, S uses zero-sequence padding, and relay nodes precode the received signals with a proper precoding matrix. The pairwise error probability (PEP) analysis is provided to investigate the achievable diversity gain of the proposed DSTBC for a general channel model in which one hop is modeled by Rayleigh fading and the other by Rician fading. This mixed Rayleigh-Rician channel model allows us to analyze two typical scenarios where {Ri} are in the neighborhood of either S or D.</P>
Network Coding-Based Retransmission for Relay Aided Multisource Multicast Networks
Vien, Quoc-Tuan,Tran, Le-Nam,Hong, Een-Kee Hindawi Publishing Corporation 2011 Eurasip Journal on Wireless Communications and Net Vol.2011 No.-
<P>This paper considers the reliable transmission for wireless multicast networks where multiple sources want to distribute information to a set of destinations with assistance of a relay. Basically, the reliability of a communication link is assured via automatic repeat request (ARQ) protocols. In the context of multisource multicast networks, the challenge is how to retransmit the lost or erroneous packets efficiently. In traditional approaches, the retransmission of lost packets from a single source is treated separately, and thus it may cause a considerable delay. To solve this problem, we propose the relay detects, combines, and forwards the packets which are lost at destinations using network coding. In the proposed ARQ protocol, the relay detects packets from different sources and combines the lost packets using NC. In particular, two packet-combination algorithms are developed to guarantee that all lost packets are retransmitted with the smallest number of retransmissions. Furthermore, we analyze the transmission bandwidth and provide the numerical results to demonstrate the superior performance of the proposed ARQ protocol over some existing schemes.</P>
압전작동기를 이용한 함정용 능동 하이브리드 마운트 시스템의 진동제어 성능 평가
벤큐오(Quoc, Nguyen Vien),최승복(Choi, Seung-Boh),오종석(Oh, Jong-Seok) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.1
In this work, a new active hybrid mount featuring piezostack actuator and rubber element is proposed, and its vibration control performance is evaluated by applying a robust frequency-shaped sliding mode controller. After describing the configuration of the proposed mount, vibration control performances are experimentally evaluated. A mount system with four active hybrid mounts is then constructed. To attenuate vibrations on the supported mass, a frequency-shaped sliding mode controller is designed and implemented to the system. Finally, control performances are obtained and presented in time and frequency domains via computer simulation.
Active Vibration Control Using Piezostack Based Mount
벤큐오(Nguyen, Vien-Quoc),최상민(Choi, Sang-Min),팽용석(Paeng, Yong-Seok),한영민(Han, Young-Min),최승복(Choi, Seung-Bok),문석준(Moon, Seok-Jun) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.4
This paper presents active vibration control performance of a hybrid mount. The proposed hybrid mount is devised by adopting both piezostack as an active actuator and rubber as a passive element. After experimentally identifying actuating force characteristics of the piezostack and dynamic characteristics of the rubber, the hybrid mount was designed and manufactured. Subsequently, a vibration control system with a specific mass loading is constructed, and its governing equations of motion are derived. In order to actively attenuate vibration transmitted from the base, a feedforward controller is formulated and experimentally realized. Vibration control responses are then evaluated in time and frequency domains.
압전작동기를 이용한 함정용 능동 하이브리드 마운트 시스템의 진동제어 성능평가
벤큐오(Nguyen Vien Quoc),최승복(Seung-Boh Choi),오종석(Jong-Seok Oh) 한국소음진동공학회 2010 한국소음진동공학회 학술대회논문집 Vol.2010 No.10
In this work, a new active hybrid mount featuring piezostack actuator and rubber element is proposed, and its vibration control performance is evaluated by applying a robust frequency-shaped sliding mode controller. After describing the configuration of the proposed mount, vibration control performances are experimentally evaluated. A mount system with four active hybrid mounts is then constructed. To attenuate vibrations on the supported mass, a frequency-shaped sliding mode controller is designed and implemented to the system. Finally, control performances are obtained and presented in time and frequency domains via computer simulation.
Chien Vien Chinh,Viet Phu Quoc,Loc Huynh Tan,Duoc Nguyen Van,Thai Pham Quang,Be Le Van 한국역학회 2021 Epidemiology and Health Vol.43 No.-
OBJECTIVES: An A/H5N1 vaccine (IVACFLU-A/H5N1) was accepted for use in Vietnam; however, antibody persistence after vaccination has not been well characterized. We examined post-vaccination antibody persistence and related risk factors in individuals enrolled in the phase II IVACFLU-A/ H5N1 vaccine trial in Ninh Hoa, Vietnam, who received a 15-μg dose (2 injections 21 days apart). METHODS: We used a longitudinal study design to follow 86 participants, without a control group. The participants tested as anti-A/H5N1 immunoglobulin G seronegative at baseline and received both doses of the vaccine. Blood was drawn at 30 months and 36 months after the complete vaccination to assess antibody status. Antibody persistence status was compared by demographic characteristics and exposure risk factors using univariate logistic regression. RESULTS: In total, 84.9% and 52.3% of the population showed persistence of at least 1/10 of the A/H5N1 antibodies at 30 months and 36 months after IVACFLU-A/H5N1 vaccination, respectively. The odds of antibody persistence were higher in older people, but lower in people who had experienced flu-like symptoms in the past 18 months or between 2 visits. We recorded no differences between A/H5N1 antibody persistence and exposure risk factors, including having a poultry farm, coming into contact with poultry, and slaughtering and processing poultry. CONCLUSIONS: This study demonstrated noteworthy antibody persistence, indicated by the seroconversion rate and geometric mean titer at 30 months and 36 months after the IVACFLU-A/H5N1 vaccine. Further studies should investigate older people and those who experienced flu-like symptoms to determine a suitable time for a booster shot.
문석준,최상민,Vien-Quoc Nguyen,오종석,최승복,정정훈,권정일,정우진 대한조선학회 2013 International Journal of Naval Architecture and Oc Vol.5 No.1
This paper has been focused on developing a new hybrid mount for shipboard equipment used in naval surface ships and submarines. While the hybrid mount studied in our previous research was 100 kg-class series-type mount, the new hybrid mount has been designed as an inertia-type mount capable of supporting a static of 500 kg. The proposed mount consists of a commercial rubber resilient mount, a piezostack actuator and an inertial mass. The piezostack actuator connected with the inertial mass generates actively the control force. The performances of the proposed mount with a newly designed specific controller have been evaluated in accordance with US military specifications and compared with the passive mount. An isolation system consisting of four proposed mounts and auxiliary devices has been also tested. Through a series of experimental tests, it has been confirmed that the proposed mount provides better performance than the US Navy's standard passive mounts.