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무선 Ad-Hoc 네트워크를 위한 흐름 기반의 Media Access Control (F-MAC)
Tran Minh Trung(Tran Minh Trung),모정훈(Jeonghoon Mo),김성륜(Seong-Lyun Kim),곽재욱(Jaewook Kwak) 한국정보과학회 2004 한국정보과학회 학술발표논문집 Vol.31 No.2Ⅲ
본 논문에서 우리는 무선 ad-hoc 네트워크에서의 효율성과 공명성 문제[2]를 해결하기 위해 기존의 802.11 MAC에서 단순한 개선으로 효율적인 결과를 얻을 수 있는 새로운 방식을 제안한다. 우리의 제안된 방식은 흐름 개념을 기반으로 하고 있다. 릴레이를 해야 하는 프레임을 가지고 있는 노드들에게 다른 노드들 보다 높은 우선순위를 할당하여 빠른 중단간의 전달함으로써 높은 성능향상을 기대할 수 있다. 또한 패킷을 전달한 후 노드는 낮은 우선순위를 갖게 되고 다른 노드에게 양보를 하여 노드들이 서로간에 공평하게 대역폭을 받을 수 있게 한다. 기존의 방식에 비해 두 배 가량 향상된 전송량과 비교적 공평하게 할당된 대역폭을 보여주는 시뮬레이션의 결과는 우리의 주장을 뒷받침해준다.
Trung, Tran Quang,Dang, Thi My Linh,Ramasundaram, Subramaniyan,Toi, Phan Tan,Park, Sang Yoon,Lee, Nae-Eung American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.2
<P>To realize the potential applications of stretchable sensors in the field of wearable health monitoring, it is essential to develop a stable sensing device with robust electrical and mechanical properties in the present of varying external conditions. Herein, we demonstrate a stretchable temperature sensor with the elimination of strain-induced interference via geometric engineering of the free-standing stretchable fibers (FSSFs) of reduced graphene oxide/polyurethane composite. The FSSFs were formed in serpentine structures and enabled the implementation of a strain-insensitive stretchable temperature sensor. On the basis of the controlled reduction time of graphene oxide, we can modulate the response and thermal index of the device. These results are attributed to the variation in the density of oxygen-containing functional groups in the FSSFs, which affect the hopping charge transport and thermal generation of excess carriers. The FSSF temperature sensor yields increased responsivity (0.8%/°C), stretchability (90%), sensing resolution (0.1 °C), and stability in response to applied stretching (±0.37 °C for strains ranging from 0 to 50%). When the sensor is sewn onto a stretchable bandage and attached to the human body, it can detect the temperature changes of the human skin during different body motions in a continuous and stable manner.</P> [FIG OMISSION]</BR>
Hierarchical codebook using the last layer to improve the angular estimation in MIMO system
Trung Hoai Tran 한국통신학회 2020 ICT Express Vol.6 No.4
The use of hierarchical codebooks in radio communication is of great interest today. However, using this codebook in transmitters and receivers in real-world transmission environments is a challenge nowadays because it is only suitable for discrete transmission directions. Therefore, the problem is to propose a discrete transmission model with a limited number of physical paths (virtual models), which is typical for the actual environment with many obstacles. The proposed use of hierarchical codebook in combination with the above virtual model can be compared with other traditional beamforming models applied to this model. The Success Detection Rate can be improved by this use of hierarchical codebook.
PER Analysis for Cooperative Multi-Hop Transmission Protocol over Nakagami-m Fading Channels
Tran Trung Duy,Hyung Yun Kong 한국전자파학회JEES 2012 Journal of Electromagnetic Engineering and Science Vol.12 No.3
In this paper, we propose a novel protocol called a Multi-hop Diversity Transmission protocol in which the retransmission is realized by a relay that is Nearest to a current Source (MDTNS). We derive the mathematical expressions of the packet error rate (PER) and the average number of transmissions over Nakagami-m fading channels, and verify them by Monte Carlo simulations. The simulation results show that the MDTNS protocol improves the performance of the network in terms of PER when compared to the Multi-hop Diversity Transmission protocol in which the retransmission is done by a relay that is Nearest to Destination (MDTND) and to the conventional multi-hop transmission(CMT) protocol.
Tran Trung Chanh,Nguyen Tan Huy,Nguyen Thu Ha,Khanh Le,Nguyen Huu Hoang The Korean Society of Plant Biotechnology 2023 JOURNAL OF PLANT BIOTECHNOLOGY Vol.50 No.2
In vitro conservation is one of the most effective strategies for rare plant protection, especially for orchid species. To maximize the success rates of in vitro explant establishment (stage I) in conservation programs, the application of tissue culture additives such as Plant Preservative Mixture<sup>TM</sup> (PPM<sup>TM</sup>) should be emphasized. In this study, we used Dendrobium thyrsiflorum Rchb.f. (1875) seeds and seedlings as a model for the evaluation of PPM<sup>TM</sup>'s phytotoxicity in the meristematic tissues of epiphytic orchids. PPM<sup>TM</sup> had no observable inhibitory effect on protocorm, shoot, or root development when it was supplemented at 0.1%. PPM<sup>TM</sup> supplementation caused adverse effects on D. thyrsiflorum explants at concentrations > 0.2%. At high concentrations, young in vitro seedlings showed damage, especially at the root tissue level. Based on this model, supplementation of 0.1-0.2% PPM<sup>TM</sup> to culture media was successfully implemented to establish in vitro cultures of other rare orchid species in our conservation program.
Maneuvering flight of beetle (Allomyrina Dichotoma)
Trung-Hieu Tran,Tien Van Truong,Tuyen Quang Le,Hoon Cheol Park,Doyoung Byun 한국항공우주학회 2009 한국항공우주학회 학술발표회 논문집 Vol.2009 No.11
Maneuvering flight has been recognized as an important characteristic of insects and animals where these species frequently use. Here we investigate kinematics and role of flexibility of hind wing of Allomyrina Dichtoma in which body and wing kinematics were reconstructed into three?dimensional through DLT method. Result shows that a flexibility of hind wing can increase performance significantly in turning and stability control of beetle especially in supination and pronation phases. In the downstroke phase, hindwing has positive wing camber, inversely, it is passive deformed into negative wing camber in chordwise as well as in span wise direction at begin of upstroke. These mechanisms can create a large variant of force and moment In magnitude and direction which can change direction and altitude of beetle in maneuvering.
A Multichannel TDMA MAC Protocol to Reduce End-to-End Delay in Wireless Mesh Networks
Tran Minh Trung,Jeonghoon Mo 한국전자통신연구원 2010 ETRI Journal Vol.32 No.5
Supporting QoS over multihop wireless mesh networks is difficult because end-to-end delay increases quickly with the increasing number of hops. This paper introduces a novel multichannel time-division multiple-access media access control (McTMAC) protocol that can help to efficiently reduce delay over multihop networks. Performance evaluation results demonstrate that McTMAC outperforms existing alternative protocols. The max-delay can be reduced by as much as 60% by using McTMAC.
Trung-Hieu Tran,Soon-Il Kim,Young-Cheol Yang,SiHyeock Lee,Young-Joon Ahn 한국응용곤충학회 2008 한국응용곤충학회 학술대회논문집 Vol.2008 No.05
The repellent constituents of essential oils from Zanthoxylum armatum (Rutaceae) seed and Zanthoxylum piperitum fruit against female Stomoxys calcitrans were analyzed by gas chromatography and gas chromatography-mass spectrometry. The repellency of two Zanthoxylum essential oils and 11 oil compounds against female S. calcitrans was examined using a skin bioassay. Results were compared with those of the most widely used repellent DEET. Both Z. armatum seed and Z. piperitum fruit oils provided complete and good protection from fly bites for 30 min at 0.4 and 0.2 mg/cm2, respectively. At 0.05 mg/cm2, both oils gave ca 70 and 40% repellency at 30 and 60 min post-treatment, respectively, whereas DEET provided 83 and 73% protection. Of test compounds, cuminaldehyde at 0.05 mg/cm2 gave 92 and 69% repellency at 10 and 30 min post-treatment, respectively, whereas 1,8-cineole, and citronellal provided approx. 76% repellency at 10 min. The Zanthoxylum oils and their constituents, particularly cuminaldehyde, merit further study as potential insect repellents for the protection from humans and domestic animals from biting and nuisance caused by S. calcitrans.
Local Gradient와 Median Filter에 근거한 초해상도 이미지 재구성
Tran Trung Hieu,조상복(Sang-Bock Cho) 大韓電子工學會 2010 電子工學會論文誌-SP (Signal processing) Vol.47 No.1
본 논문은 높은 품질 SR 이미지를 획득하기 위해 국소 그라디언트를 기반으로 적응형 보간법을 이용하는 SR 방법을 제공한다. 이 방법에서, 내삽 화소와 인접하는 유효한 화소 사이에 거리는 국소 그라디언트 특징을 이용하여 고려되며, 보간 계수는 LR 이미지의 국소 그라디언트를 고려한다. 픽셀의 국소 그라디언트는 더 작을수록, 그리고 메디안 필터는 보간된 HR 이미지의 블러링과 노이즈를 감소시키기 위해 적용된다. 실험 결과는 특히 이미지의 에지 부분에서, 다른 방법과 비교하여 제안된 방법의 유효성을 보여준다. This paper presents a SR method using adaptive interpolation based on local gradient features to obtain a high quality SR image. In this method, the distance between the interpolated pixel and the neighboring valid pixel is considered by using local gradient properties. The interpolation coefficients take the local gradient of the LR images into account. The smaller the local gradient of a pixel is, the more influence it should have on the interpolated pixel. And the median filter is finally applied to reduce the blurring and noise of the interpolated HR image. Experiment results show the effectiveness of the proposed method in comparison with other methods, especially in the edge areas of the images.