Browsing by Author "Chen, CY"

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40-GHz coplanar waveguide bandpass filters on silicon substrate
(2002-11-01)
Chan, KT
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Chen, CY
;
Chin, A
;
Hsieh, JC
;
Liu, J
We report a very simple process to fabricate high performance filter on Si at 40 GHz; using proton implantation. The filter has only -3.4-dB loss at peak transmission of 40 GHz; with a broad 9-GHz bandwidth. In sharp contrast, the filter on 1.5-mum SiO2 isolated Si has much worse transmission and reflection loss. This is the first demonstration of high performance filter at millimeter-wave regime on Si with process compatible to current VLSI technology.
A liquid crystal phase shifter with a tuning range of over 360 degrees around 1 THz
(2005)
Chen, CY
;
Hsieh, CF
;
Pan, RP
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Pan, CL
;
光電工程學系
Tunable phase shift over 271 radians (360 degrees) at THz frequencies is achieved with a sandwiched liquid crystal (LC) cell operated over a broad range using magnetically controlled birefriengence.
A liquid-crystal-based terahertz tunable Lyot filter
(2005)
Pan, RP
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Chen, CY
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Hsieh, CF
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Pan, CL
;
電子物理學系
A tunable Lyot filter operating in the terahertz frequency range is demonstrated by using fixed and variable nematic liquid crystals.
A necessary condition for a graph to be the visibility graph of a simple polygon
(2002-04-06)
Chen, CY
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應用數學系
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Department of Applied Mathematics
Two vertices of a simple polygon P are visible if the line segment joining them does not intersect the exterior of P. The visibilitly graph of P is a graph G obtained by representing each vertex of P by a vertex of G and two vertices of G are joined by an edge if and only if their corresponding vertices in P are visible. A graph G is a visibility graph if there exists a simple polygon P such that G is isomorphic to the visibility graph of P. No characterization of visibility graphs is available. Coullard and Lubiw derived a necessary condition for a graph to be the visibility graph of a simple polygon. They proved that any 3-connected component of a visibility graph has a 3-clique ordering starting from any triangle. However, Coullard and Lubiw insisted on the non-standard definition of visibility (the line segment joining two visible vertices may not go through intermediate vertices) and they said they do not know if their result will hold under the standard definition of visibility. The purpose of this paper is to prove that Coullard and Lubiw's result still holds under the standard definition of visibility. (C) 2002 Elsevier Science B.V. All rights reserved.
A new subliminal channel based on Fiat-Shamir's signature scheme
(1995-11-01)
Chen, CY
;
Chang, CC
;
Yang, WP
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資訊工程學系
;
Department of Computer Science
This paper constructs a subliminal channel in a RSA-like variant of the Fiat-Shamir signature scheme to transfer any secret information. The proposed subliminal channel, unlike that in El-Gamal signature scheme, can avoid the serious shortcoming that a subliminal receiver can undetectably forge a signer's signature. In addition, our channel also overcomes almost all shortcomings from which the subliminal channel in El-Gamal signature scheme suffer.
A new subliminal channel based on Fiat-Shamir's signature scheme
(1995-11-01)
Chen, CY
;
Chang, CC
;
Yang, WP
;
資訊工程學系
;
Department of Computer Science
This paper constructs a subliminal channel in a RSA-like variant of the Fiat-Shamir signature scheme to transfer any secret information. The proposed subliminal channel, unlike that in El-Gamal signature scheme, can avoid the serious shortcoming that a subliminal receiver can undetectably forge a signer's signature. In addition, our channel also overcomes almost all shortcomings from which the subliminal channel in El-Gamal signature scheme suffer.
A novel algal toxicity testing technique for assessing the toxicity of both metallic and organic toxicants
(2005-05-01)
Lin, JH
;
Kao, WC
;
Tsai, KP
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Chen, CY
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環境工程研究所
This study presents a closed-system algal toxicity test technique that is capable of detecting the effects of both organic and metallic toxicants. Toxicity testing was conducted by transferring adequate amounts of algal suspension, dilution water (with culture growth medium), and toxicants into 300-mL BOD bottles. The BOD bottles were completely filled up with no head-space left. The initial cell density and the exposure time were 15,000 cells/mL and 48 h, respectively. The performance of the above test method was evaluated using three heavy metals and six organic toxicants based on three different test endpoints, i.e., dissolved oxygen production, algal growth rate, and cell density. The proposed test revealed excellent test sensitivity and reproducibility. Currently, none of the existing algal toxicity test protocols is adequate for assessing the toxicity of organic chemicals. The closed-system algal toxicity tests developed by previous researchers also may not be ideal because the enlarged headspace and/or enriched bicarbonate buffer may result in either underestimations of the exposure concentrations or insensitive responses to both heavy metals and organic toxicants. Compared to the aforementioned algal toxicity test methods, the proposed technique in the present study has a more general applicability under conditions such as effluent samples containing both metals and organic toxicants or samples with unknown compositions. (c) 2005 Elsevier Ltd. All rights reserved.
A novel tunable diode laser with liquid crystal intracavity tuning element
(2004)
Pan, RP
;
Lan, YP
;
Chen, CY
;
Pan, CL
;
電子物理學系
We propose a novel and simple approach for tuning of the laser wavelength. A homogeneously aligned nematic liquid crystal (NLC) cell with 4'-n-pentyl-4-cyanobiphenyl (5CB) is inserted in an external-cavity semiconductor laser as the fine-tuning element of wavelength. Varying the voltage biasing the NLC cell, its extraordinary index of refraction would change due to field-induced reorientation of the LC director. This is equivalent to tune the laser cavity length. As a result, the laser wavelength can be continuously tuned. With a NLC cell 35.5 mum in thickness, the output frequency of the present laser can be tuned over 4 GHz for a 30-cm-long laser cavity without hopping. The driving rms voltage was less than 2 volts.
A simple algorithm to find the steps of double-loop networks
(2002-09-15)
Chan, RCF
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Chen, CY
;
Hong, ZX
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應用數學系
;
Department of Applied Mathematics
Double-loop networks have been widely studied as architecture for local area networks and it is well-known that the minimum distance diagram of a double-loop network yields an L-shape. Given an N, it is desirable to find a double-loop network DL(N;s(1),s(2)) with its diameter being the minimum among all double-loop networks with N stations. Since the diameter can be easily computed from an L-shape, one method is to start with a desirable L-shape and then asks whether there exist s(1) and s(2) (also called the steps of the double-loop network) to realize it. In this paper, we propose a simple and efficient algorithm to find s(1) and s(2), which is based on the Smith normalization method of Aguilo, Esque and Fiol. (C) 2002 Elsevier Science B.V. All rights reserved.
A stabilized and tunable erbium-doped fiber ring laser with double optical filter
(2004-03-01)
Yeh, CH
;
Lee, CC
;
Chen, CY
;
Chi, S
;
光電工程學系
We have proposed and experimentally demonstrated a stabilized and tunable erbium-doped fiber ring laser by using a Fabry-Perot laser and a fiber Fabry-Wrot filter. The sidemode suppression ratio of >30 dB/0.1 nm and the output power of >2.2 dBm can be achieved while this ring laser is tuned from 1528.28 to 1559.64 nm with the step of 1.12 nm. The wavelength variation of less than 0.01 nm and the power fluctuation of less than or equal to0.04 dB have also been obtained. When the constant output power is controlled by adjusting the bias current of 980-nm pump laser, the power variation of less than +/-0.05 dB can be obtained over the entire tunable range.
A tunable C-plus-L-band fiber ring laser based on hybrid amplifier
(2004-02-01)
Yeh, CH
;
Lee, CC
;
Chen, CY
;
Chi, S
;
光電工程學系
A tunable C-plus-L-band fiber ring laser, based on a semiconductor optical amplifier, which directly connects an erbium-doped fiber amplifier with a 16 m long erbium-doped fiber, has been proposed and experimentally investigated. A side-mode suppression ratio of > 40 dB/0.1 nm and an output power of >3 dBm in the operating range from 1552 to 1610 nm have been achieved for this ring laser.
Adaptive order tracking technique using recursive least-square algorithm
(2002-10-01)
Bai, MSR
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Jeng, J
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Chen, CY
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機械工程學系
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Department of Mechanical Engineering
Order tracking technique is one of the important tools for diagnosis of rotating machinery Conventional methods of order tracking are primarily based on Fourier analysis with reference to shaft speed. Resampling is generally required in the fast Fourier transform (FFT)-based methods to compromise between time and frequency resolution for varying shaft speeds. Conventional methods suffer from a number of shortcomings. In particular smearing problems arise when closely spaced orders or crossing orders are present. Conventional methods also are ineffective for the applications involving multiple independent shaft speeds. This paper presents an adaptive order tracking technique based on the Recursive Least-Squares (RLS) algorithm to overcome the problems encountered in conventional methods. In the proposed method, the problem is treated as the tracking of frequency-varying bandpass signals. Order amplitudes can be calculated with high resolution by using the proposed method in real-time fashion. The RLS order tracking technique is applicable whether it is a single-axle or multi-axle system.
An analysis of the combined effects of organic toxicants
(2002-04-22)
Chen, CY
;
Lu, CL
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環境工程研究所
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Institute of Environmental Engineering
This paper presents a basic database for the joint actions of 44 binary mixtures of various organic toxicants on Escherichia coli. The multiple toxicity behaviors observed from the E. coli organisms were analyzed and compared with previous works based on the Microtox tests, The two kinds of tests produced quite different responses, in terms of the joint action mode and the sum of toxic units, to various organic mixtures. However, detailed analyses with the considerations of the chemical's mechanisms of toxicity and the slope of toxicant's dose-response curve have revealed several general criteria for the prediction of combined effects of organic toxicants. First, for both reactive and non-reactive toxicants, either additive or less than additive (antagonistic) joint actions will be observed for chemicals of the same mechanism of toxicity. Second, the mixture of reactive toxicants with different mechanisms is the only category of organic mixtures associated with frequent observations of synergism. Third, greater-than-additive (synergistic) effects are inherently associated with toxicants having flat dose-response curves. Less than additive effects are, however, mainly related to a chemical's display steep close-response curves. Model analyses indicate that the observed synergistic effects are due to response addition or response multiplication joint actions. Hence, most of the synergistic joint actions are non-interactive in nature and are governed by the dose-response relationships of individual toxicants. (C) 2002 Elsevier Science B.V. All rights reserved.
An efficient tag-based routing algorithm for the backward network of a bidirectional general shuffle-exchange network
(2006-04-01)
Chen, CY
;
Lou, JK
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應用數學系
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Department of Applied Mathematics
This letter considers the problem of designing efficient routing algorithms for the backward network of a bidirectional general shuffle-exchange network (BNBGSEN for short); switch elements in the network are of size k x k. It has been shown in [1] that the algorithm in [5] can be used to obtain (as many as k) backward control tags for a source j to get to a destination i in a BNBGSEN. In this letter, we show that a BNBGSEN has a wonderful property: for each destination i, there are two backward control tags associated with it such that every source j can get to i by using one of the two tags. We use this property to derive an efficient tag-based routing algorithm.
An encryption/multisignature scheme with specified receiving groups
(1998-03-01)
Hwang, SJ
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Chen, CY
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Chang, CC
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資訊工程學系
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Department of Computer Science
In this paper, we propose a new multisignature scheme that allows all of the signers to specify the recipients. The encryption function is also integrated into our multisignature scheme, thus the new scheme can provide secrecy, authenticity, and integrity services. Moreover, the message expansion is also reduced. Comparing to the proposed multisignature scheme, the new scheme is the first one which allows the singers to specify the recipients.
Any maximal planar graph with only one separating triangle is hamiltonian
(2003-03-01)
Chen, CY
;
應用數學系
;
Department of Applied Mathematics
A graph is hamiltonian if it has a hamiltonian cycle. It is well-known that Tutte proved that any 4-connected planar graph is hamiltonian. It is also well-known that the problem of determining whether a 3-connected planar graph is hamiltonian is NP-complete. In particular, Chvatal and Wigderson had independently shown that the problem of determining whether a maximal planar graph is hamiltonian is NP-complete. A classical theorem of Whitney says that any maximal planar graph with no separating triangles is hamiltonian, where a separating triangle is a triangle whose removal separates the graph. Note that if a planar graph has separating triangles, then it can not be 4-connected and therefore Tutte's result can not be applied. In this paper, we shall prove that any maximal planar graph with only one separating triangle is still hamiltonian.
Applications of semiconductor nanoparticles in electron transfer, energy transfer and metal ion recognition.
(2004-08-22)
Chou, YH
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Chiu, HT
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Chen, CY
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Cheng, CT
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Chou, PT
Backside copper metallization of GaAs MESFET's using Ta and TaN as diffusion barrier
(2000)
Chang, EY
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Chen, CY
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Chang, L
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Chen, SH
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材料科學與工程學系
Backside copper metallization of GaAs MESFET's ( Metal Semiconductor Field Effect Transistor) using Ta and TaN as the diffusion barrier layers was studied. A thin diffusion barrier Ta(40nm) or TaN(40nm) was sputtered on the GaAs substrate as the diffusion barrier for copper metallization. Material reactions of these films with GaAs substrate at different annealing temperatures were characterized by X-ray diffraction, Auger electron spectroscopy and transmission electron microscopy. Copper and diffusion barrier layer films were very stable up to 500 degrees C. At higher temperatures, Ta atoms started to react with GaAs substrate to form TaAs and TaAs, and Cu atoms started to penetrate into the GaAs substrate. The backside of the GaAs MESFET's was metallized using these Cu/Ta and Cu/TaN films. After 300 degrees C 2 hr annealing, the MESFET's showed very little change in the device characteristics. The experimental results show that both Ta and TaN are good diffusion barriers for backside copper metallization in GaAs devices.
Backside copper metallization of GaAs MESFETs using TaN as the diffusion barrier
(2001-06-01)
Chen, CY
;
Chang, EY
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Chang, L
;
Chen, SH
;
材料科學與工程學系
Backside copper metallization of GaAs MESFETs using TaN as the diffusion barrier was studied. A thin TaN layer of 40 nm was sputtered on the GaAs substrate before copper firm metallization. As judged from the data of X-ray diffraction (XRD), Anger electron spectroscopy (AES), and cross-sectional transmission electron microscopy (TEM), the Cu/TaN films with GaAs were very stable without interfacial interaction up to 550 OC annealing, The copper metallized MESFETs were thermally stressed at 300 degreesC, The devices showed very little change in the device characteristics (<3 %) after thermal stress, and the changes of the electrical parameters and RF characteristics of the devices after thermal stress were of the same order as those devices without Cu metallization, These results show that TaN is a good diffusion barrier for Cu in GaAs devices and the Cu/TaN films can be used for the backside copper metallization of GaAs MESFETs.
Broadband C- plus L-band double-ring fiber baser based on a two-stage hybrid amplifier
(2005-10-01)
Yeh, CH
;
Cheng, BC
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Chen, CY
;
Chi, S
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光電工程學系
A stable and wavelength-tunable C- plus L-band fiber double-ring laser, which uses a two-stage hybrid amplifier with a semiconductor optical amplifier and an erbium-cloped fiber amplifier, has been proposed and experimentally demonstrated. Based on the double-ring configuration, the proposed fiber ring laser exhibits more stable output wavelengths and powers than the single-ring laser. A wide tunable range of 1540 to 1620 nm, a side-mode suppression ratio (SMSR) of > 31.2 dB/0.05 nm over a wide tuning range from 1550 to 1612 nm, and an output power of > 2 dBm over the operation range of 1546 to 1608 nm have been achieved. (c) 2005 Society of Photo-Optical Instrumentation Engineers.