Browsing by Author "Chen, CK"

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A hybrid overlay multicast routing protocol for mobile ad hoc networks
(2005)
Chen, CK
;
Wang, KC
;
Lee, LS
;
資訊工程學系
;
Department of Computer Science
We propose a novel multicast routing protocol, called Hybrid Overlay Multicast Routing Protocol (HOMRP) for MANETs (Mobile Ad hoc NETworks). Existing overlay and mesh multicast routing protocols in MANETs have the main drawback of low packet delivery ratio and high control overhead, respectively. In order to improve these shortcomings, we integrate multicasting and unicast tunnels for efficient packet delivery. In HOMRP, it creates multiple local multicast trees. Each pair of parent node and child node in a local multicast tree is at a distance of one-hop. It uses multicasting to deliver multicast packets in local multicast trees. This will provide efficient data forwarding. Unicast tunnels are used for transmitting packets between local multicast trees. Simulation results have shown that the packet delivery ratio of HOMRP is 50% better than that of AMRoute and is close to that of ODMRP. HOMRP reduces 18% control overhead compared to ODMRP and reduces 9% end-to-end packet delay compared to AMRoute.
Formal synthesis of vallesamidine
(2006)
Ho, TL
;
Chen, CK
;
應用化學系
;
Department of Applied Chemistry
A novel route to the racemic selenide (1RS, 12bRS)-1-ethyl -2,3,6,7,12,12b-hexahydro-1- [2(phenylseleno)ethyl]indolo[2,3-a]quinolizin-4(1H)-one (13b), a key intermediate in the total synthesis of vallesamidine (1), was elaborated. Compound 3a, obtained by Pictet-Spengler reaction of tryptamine and cyclohept-4-enyl-1-carbaldehyde (2c), was oxidized with KMnO4 to the diacid 4, which was subsequently converted into the isomeric tetracyclic lactams 5a,b. After proper protection maneuvers, Barton decarboxylation of 10a,b, trapping with PhSe2Ph, and Boc removal afforded 13b.
Noise-tolerant XOR-based conditional keeper for high fan-in dynamic circuits
(2005)
Hua, CH
;
Hwang, W
;
Chen, CK
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Noise-tolerant XOR-based conditional keeper for high fan-in dynamic circuits is presented in this paper. Noise immunity is enhanced by conditionally turning on the conditional keepers. The conditional keeper is turned off at some critical moments to reduce the delay and power consumption. The timing of control signals and their effects on noise immunity, power and delay are also examined. High fan-in dynamic circuits are used to demonstrate the effectiveness of the conditional keeper on noise immunity. Distributed power gating combined with clock gating design is also examined. An the simulation results are based on TSMC 100nm CMOS technology. Compared to conventional techniques, under the same unity-gain DC noise criteria, more than 20% power reduction and 20% delay reduction are achieved. Under the same delay criteria, more than 1.25X noise immunity improvement is attained.
Novel poly(2,3-biphenyl-1,4-phenylenevinylene) derivatives containing long branched alkoxy and fluorenyl substituents: Synthesis, characterization, and their applications for polymer light-emitting diodes
(2005-10-18)
Chen, KB
;
Li, HC
;
Chen, CK
;
Yang, SH
;
Hsieh, BR
Two series of poly(2,3-Biphenyl-1,4-phenylenevinylene) (DP-PPV) derivatives containing long branched alkoxy chains or fluorenyl substituents were synthesized. The branched alkoxy groups were introduced to enhance the solubility for spin-coating processes. Bulky fluorenyl groups with two hexyl chains on the 9-position were introduced to increase steric hindrance and prevent close packing of the main chain. By controlling the feed ratio of different monomers during polymerization, DP-PPV derivatives with high molecular weights were obtained. All synthesized polymers possess high glass transitions temperatures and thermal stabilities. The maximum photoluminescent emissions of the thin films are located between 498 and 564 nm. Cyclic voltammetric analysis reveals that the band gaps of these light-emitting materials are in the range from 2.4 to 2.5 eV. A double-layer electroluminescent device with the configuration of ITO/PEDOT/polymer 2/Ca/Al exhibited a low turn-on voltage (4.0 V), a very high external quantum efficiency (3.39 cd/A), and a high brightness (16 910 cd/m(2)).
Parallelization of multiple genome alignment
(2005)
Li, YM
;
Chen, CK
;
電信工程研究所
;
友訊交大聯合研發中心
;
Institute of Communications Engineering
In this work, we implement a genome alignment system which applies parallelization schemes to the ClustalW algorithm and the interface of database querying. Parallel construction of the distance matrices and parallelization of progressive alignment in the ClustalW algorithm are performed on PC-based Linux cluster with message-passing interface libraries. Achieved experiments show good speedup and significant parallel performance.
Structural amendment and stereoselective synthesis of mutisianthol
(1997-05-16)
Ho, TL
;
Lee, KY
;
Chen, CK
;
應用化學系
;
Department of Applied Chemistry
cis-1-(5-Acetoxy-3,6-dimethyl-1-indanyl)-2-methyl-1-propene synthesized from 3,6-dimethyl-1-indanone was found to be different from mutisianthol by spectral comparison. The presence of a high-field signal in the NMR spectrum of the final product and various intermediates, characteristic of the cis-1,3-dialkylindanes but absent in the spectrum of the natural terpene, suggests a revision of the structure of mutisianthol to the trans isomer. The trans-indane which was subsequently obtained indeed exhibits data fully agreeable with mutisianthol. A similar stereochemical revision for jungianol is also indicated.
Structural amendment and stereoselective synthesis of mutisianthol
(1997-05-16)
Ho, TL
;
Lee, KY
;
Chen, CK
;
交大名義發表
;
應用化學系
cis-1-(5-Acetoxy-3,6-dimethyl-1-indanyl)-2-methyl-1-propene synthesized from 3,6-dimethyl-1-indanone was found to be different from mutisianthol by spectral comparison. The presence of a high-field signal in the NMR spectrum of the final product and various intermediates, characteristic of the cis-1,3-dialkylindanes but absent in the spectrum of the natural terpene, suggests a revision of the structure of mutisianthol to the trans isomer. The trans-indane which was subsequently obtained indeed exhibits data fully agreeable with mutisianthol. A similar stereochemical revision for jungianol is also indicated.
Synthesis of eburnamine, isoeburnamine, and eburnamonine via a spirocyclic intermediate
(2005)
Ho, TL
;
Chen, CK
;
應用化學系
;
Department of Applied Chemistry
Racemic eburnamonine (1) was synthesized via 6, an intermediate possessing local symmetry. Cleavage of the cyclopentene subunit led to pentacyclic aldehydes 8a/8b which on subsequent borohydride and Wolff-Kishner reductions gave 12. The final steps included a RuCl3-catalyzed periodate oxidation and pyridimum chlorochromate (PCC) oxidation. The penultimate intermediates were racemic eburnamine (2) and racemic isoeburnamine (3).
Synthesis of tangutorine
(2006)
Ho, TL
;
Chen, CK
;
應用化學系
;
Department of Applied Chemistry
Tangutorine (1) in the racemic form has been assembled from tryptamine and aldehyde 3. The synthetic design was based on uncovering a hidden symmetry in the nontryptamine portion of the norketone 2. A five-step process with an overall yield of 7% was developed in which 2 was transformed into the target molecule via a Vilsineier-Haack reaction and two reduction steps.