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Dileep Kumar Singh,김진우,성종혁,김익연 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.2
Biological screening of the natural products from Dalbergia oliveri identified that (6aR,11aR)-3,8-dihydroxy-9-methoxypterocarpan and (3R)-7,2′-dihydroxy-4′,5′-dimethoxyisoflavanone significantly increased the proliferation of dermal papilla cells and subcutaneous injection of these compounds induced the anagen of hair cycle in animal models. These interesting biological activities led us to design a practical synthetic route to these natural products for further pharmacological evaluation. Here we report the first total syntheses of naturally occurring pterocarpan ((6aR,11aR)-3,8-dihydroxy-9-methoxypterocarpan), isoflavan ((3R)-5′-methoxyvestitol), and isoflavanone ((3R)-7,2′-dihydroxy-4′,5′-dimethoxyisoflavanone) in a racemic form. A mild ZnCl2-mediated [3 + 2] annulation method was utilized with chromenes and 2-methoxy-1,4-benzoquinone to construct a pterocarpan framework in a one-pot manner. O-methylation and reductive cleavage of the benzylic C─O bond afforded 5′-methoxyvestitol, which was transformed to isoflavanone, 7,2′-dihydroxy-4′,5′-dimethoxyisoflavanone, via a three-step sequence including DDQ-mediated benzylic oxidation.
Dileep K G,Pradeep Goutam,Laxmaiah P,Nithin Kumar S,Hari Prasad S V,Nithin B 대한전자공학회 2017 대한전자공학회 학술대회 Vol.2017 No.1
This paper demonstrates the implementation of a QPSK/Time Division Multiple Access (TDMA) satellite receiver using short preamble-based synchronization in the presence of timing, frequency and phase offsets, and with Additive White Gaussian Noise (AWGN). The detection and estimation of synchronization parameters of the received signal, i.e., frequency, phase and symbol timing, are highly dependent on the preamble of the burst. Moreover, computational complexity and acquisition time of the receiver are directly proportional to the preamble length. The implemented receiver uses a 64-bit short preamble for synchronization and gives better bit error rate (BER) performance at low signal to noise ratio (SNR), close to -3dB. The functional verification of the synchronization algorithm is done using Matlab simulations and the algorithm implementation uses fixed-point C. The receiver design has been prototyped for 4 TDMA channels in Texas Instruments (TI) multi-core C66x DSP. The design and implementation of this receiver have been done for C-DOT indigenous satellite project.
Dileep Chandran Ramachandran,Siva Prasad Murugan,Young‑Min Kim,Dongcheol Kim,Gwang‑Gook Kim,Dae‑Geun Nam,Chanyoung Jeong,Yeong Do Park 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9
The corrosion behavior of fusion zones (FZ-1: 5.39 Mg–0.66Mn, FZ-2: 5.49 Mg–0.35Mn, and FZ-3: 5.72 Mg–0.32Mn)of AA5083 alloy welded with high Mg-containing Al–Mg filler wires has been systematically investigated. An extensivemicrostructural characterization was performed to evaluate the localized corrosion properties of the fusion zones. Thepotentiodynamic polarization test and salt spray test showed that the corrosion resistance decreases with increasing Mg content,therefore, the corrosion resistance of FZ-3 is lower than that of the FZ-1 and FZ-2. The electron microscopic analysisafter intermittent corrosion test revealed that the eutectic β-phase (Al3Mg2) was responsible for the initiation of corrosion. The corrosion behavior of each microstructural constituents was related to the dissolution potentials of the correspondingmicrostructures; hence, it forms galvanic couple with the Al matrix. Moreover, high Mg content in the filler wire lead to theformation of additional β-phase in the fusion zone. However, intermetallics such as Al6(Fe,Mn) and Mg2Siwere significantonly during the later stages of corrosion.
Intelligent Distance Controller for Humanoid Robot Arms Handling a Common Object
Dileep K Bhogadi,Hyun Chan Cho(조현찬),Kwang Sun Kim(김광선),Sara Wilson 한국지능시스템학회 2008 한국지능시스템학회 학술발표 논문집 Vol.18 No.1
The main object of this paper is concentrated on distance control of two robot arms of a humanoid using Fuzzy Logic Controller (FLC) for handling a common object. Serial Link Robot arms are widely used in most significantly in Humanoids serving for older people and also in various industrial applications. A method is proposed here that separates the interconnections between two robot arms so that the resulting model of two arms is decomposed into fuzzy logic based controller. The distance between two end effectors is always kept equal to that of the diameter of an object to be handled, so that the object would not fall down. Mathematical model of this system was obtained to simulate the behavior of serial robotic arms in close loop control before using fuzzy logic controller. Lagrangian equation of motion has been used to obtain the appropriate mathematical model of Robotic arms. The results are shown to provide some improvement over those obtained by more conventional means.