Browsing by Author "Lee, CJ"

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A broadband microstrip-to-waveguide transition using planar technique
(2001)
Lee, CJ
;
Wu, HS
;
Tzuang, CKC
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電信工程研究所
;
Institute of Communications Engineering
This paper presents a novel methodology, which employs a multi-layer structure to act as an interconnection between microstrip and rectangular waveguide. A Ka-band microstrip-to-waveguide transition consisting of two back-to-back mode converters are designed and implemented on the microwave printed circuit board. The field-matching between the microstrip and the partially filled rectangular waveguide can obtain great scattering characteristics of over 40% bandwidth and low transmission loss of -0.28 dB. These attractive performances indicate that the proposed microstrip-to-waveguide transition can provide a feasible approach to integrate all the RF front-end components in one module by using conventional PCB (printed circuit board) fabrication process.
A fully all-planar integrated Ka-band FSK transceiver module
(2001)
Lee, CJ
;
Hung, TP
;
Lin, SC
;
Wu, HS
;
Tsai, CY
An open RFIC (Radio Frequency Integrated Circuit) architecture employing ACSS (Advanced Coplanar Strips System) guiding technology is presented in this paper. This approach can integrate all the RF front-end components in one module using conventional PCB (printed circuit board) fabrication process. A 10 Mb/s FSK signal is upconverted to 30.18 GHz and 30.28 GHz and broadcasted through a cone-shaped antenna at power level of 10 dBm. The received signal is directly converted to baseband by even harmonic quadrature mixer, which shows a great isolation of 30 dB between RF and LO signal. The measured waveforms of the reported transceiver demonstrate the potential of constructing the wireless system with all-planar integrated circuits.
Electrical properties of rapid thermal-enhanced low pressure chemical vapor deposited Ta2O5 thin films
(1999-03-01)
Lee, CJ
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Huang, LT
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Ezhilvalavan, S
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Tseng, TY
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電子工程學系及電子研究所
Electrical properties of rapid thermal-enhanced low pressure chemical vapor deposited Ta2O5 thin films subjected to an in situ two-step postannealing process were studied. Films treated by rapid thermal annealing in O-2 at 550 degrees C for 90 s followed by plasma O-2 at 550 degrees C for 30 s exhibit a leakage current density of 7.91 x 10(-9) A/cm(2) at an applied electric field of 100 kV/cm and a dielectric constant of similar to 38. The decrease in leakage current density of the annealed Ta2O5 films in comparison to the as-deposited films is attributed mainly to the effective reduction of carbon impurities and oxygen vacancies by the two-step postannealing process. (C) 1999 The Electrochemical Society. S1099-0062(98)08-064-X. All rights reserved.
Extracting randomness from multiple independent sources
(2005-06-01)
Lee, CJ
;
Lu, CJ
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Tsai, SC
;
Tzeng, WG
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資訊科學與工程研究所
We study the problem of deterministically extracting almost perfect random bits from multiple weakly random sources that are mutually independent. With two independent sources, we have an explicit extractor which can extract a number of random bits that matches them best construction currently known, via the generalized leftover hash lemma. We also extend our construction to extract randomness from more independent sources. One nice feature is that the extractor still works even with all but one source exposed. Finally, we apply our extractor for a cryptographic task in which a group of parties wants to agree on a secret key for group communication over an insecure channel, without using ideal local randomness.
SOAP request scheduling for differentiated quality of service
(2005)
Tien, CM
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Lee, CJ
;
Cheng, PW
;
Lin, YD
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資訊工程學系
This paper presents a SOAP request scheduling algorithm for differentiated quality of service. The scheduling algorithm can be deployed on a Web services server or any server that processes SOAP requests. Due to the resource-intensive security processing of SOAP messages, this research implements the scheduling algorithm on a QoS security server. The security server schedules the requests forwarded from the Web services server for the security processing and then sends the valid requests back to the Web services server for executing the Web services. The design of the scheduling algorithm is derived from the traditional deficit round-robin scheduling. However, the scheduling algorithm schedules requests according to the probed CPU resource consumption of requests. In the evaluation, the scheduling algorithm reveals the service differentiation on the throughput and response time and the little scheduling overhead. The resource utilizations are measured to prove the security processing is much more resource-intensive than the Web services execution.
Synthesis of ferroelectric liquid crystalline polymers by ring opening polymerization
(1996)
Hsu, CS
;
Lee, CJ
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
The synthesis of two series of side-chain liquid crystalline polyoxetanes and polyoxiranes containing 4-alkanyloxybiphenyl-4'-yl (2S,3S)-2-chloro-3-methylvalerate side groups is presented. Differential scanning calorimetry, polarizing optical microscopy, and X-ray diffractometry reveal smectic mesomorphism for all obtained polymers. Most of the prepared polyoxetanes present smectic A and chiral smectic C phases. The polyoxetane containing tweleve methylene units in the spacer is the only one showing two enantiotropic smectic A and B phases. All of the obtained polyoxiranes display two enantiotropic smectic A and B phases. Although the polyoxetane and polyoxirane backbones are more flexible than the polymethacrylate backbone, side-chain crystallization do not occur in any of the synthesized polymers.