Browsing by Author "Chen, YK"

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A fuzzy reasoning based diagnosis system for (X)over-bar control charts
(2001-03-01)
Hsu, HM
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Chen, YK
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工業工程與管理學系
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Department of Industrial Engineering and Management
This paper describes a new diagnosis system, which is based on fuzzy reasoning to monitor the performance of a discrete manufacturing process and to justify the possible causes. The diagnosis system consists chiefly of a knowledge bank and a reasoning mechanism. The knowledge bank provides knowledge of the membership functions of unnatural symptoms that are described by Nelson's rules on (X) over bar control charts and knowledge of cause-symptom relations. We develop an approach called maximal similarity method (MSM) for knowledge acquisition to construct the fuzzy cause-symptom relation matrix. Through the knowledge bank, the diagnosis system can first determine the degrees of an observation fitting each unnatural symptom. Then, using the fuzzy cause-symptom relation matrix, we can diagnose the causes of process instability. In conclusion we provide a numerical example to illustrate the system.
Dynamically selective multiwavelength cross-connect based on fibre Bragg gratings and mechanical optical switches
(1998-02-01)
Chen, YK
;
Liaw, SK
;
Lee, CC
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光電工程研究所
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Institute of EO Enginerring
A dynamically selective multiwavelength cross-connect for wavelength division multiplexed (WDM) networks based on fibre Bragg gratings (FBGs) and optical switches is reported. Dynamically single-or multi-channel cross-connect functionality can be realized according to control of the optical switches and the FBGs' arrangement. Bit-error-rate performance with negligible power penalty is achieved in a 2.5 Gb s(-1) x 3 WDM channels over 100 km conventional single-mode fibre (SMF) network demonstration. The characteristics of low channel crosstalk, uniform channel loss, high scalability and cascadability, and low cost of this device could provide more reconfiguration flexibility and network survivability for WDM networks.
Dynamically selective multiwavelength cross-connect based on fibre Bragg gratings and mechanical optical switches
(1998-02-01)
Chen, YK
;
Liaw, SK
;
Lee, CC
;
光電工程學系
;
Department of Photonics
A dynamically selective multiwavelength cross-connect for wavelength division multiplexed (WDM) networks based on fibre Bragg gratings (FBGs) and optical switches is reported. Dynamically single-or multi-channel cross-connect functionality can be realized according to control of the optical switches and the FBGs' arrangement. Bit-error-rate performance with negligible power penalty is achieved in a 2.5 Gb s(-1) x 3 WDM channels over 100 km conventional single-mode fibre (SMF) network demonstration. The characteristics of low channel crosstalk, uniform channel loss, high scalability and cascadability, and low cost of this device could provide more reconfiguration flexibility and network survivability for WDM networks.
Enhanced mode-adaptive fine granularity scalability
(2003)
Peng, WH
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Chen, YK
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
In this article, we present a scalable video compression algorithm to deliver higher compression efficiency with limited drifting error. MPEG-4 Fine Granularity Scalability (FGS) compresses the video into a base layer and an enhancement layer. Currently, because the enhancement layer is predicted from the poor-quality base layer, the compression efficiency is low. To improve the compression efficiency, we construct enhancement-layer predictors from (1) macroblocks of current reconstructed base-layer frame, (2) macroblocks of previously reconstructed enhancement-layer frame, and (3) the average of previous two. On the other hand, the unpredictable receiving manner of enhancement layer could cause predictor mismatch error. The predictor mismatch error further results in drifting error. To minimize the drifting error, we create an adaptive mode-selection algorithm, in the encoder, which first smartly estimates possible drifting error of the decoder side and then uses the best macroblock modes wisely. In this article, we show that predictors constructed jointly from the base-layer frame and the enhancement-layer frame can reduce the drifting error. And, predictors constructed from the base-layer frame can stop the drifting error. As compared to other advance FGS schemes, our algorithm shows 0.3-0.5 dB PSNR improvement with a less complex structure. Although compared to MPEG-4 FGS, more than 1-1.5 dB quality improvement can be gained. (C) 2004 Wiley Periodicals, Inc.
Fiber Bragg grating-based large nonblocking multiwavelength cross-connects
(1998-10-01)
Chen, YK
;
Lee, CC
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光電工程學系
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Department of Photonics
Multiwavelength cross-connects (WXC's) will play a key role to provide more reconfiguration flexibility and network survivability in wavelength division multiplexing (WDM) transport networks. In this paper, we utilize three different fiber Bragg grating (FBG)-based P-type, S-type, and N-type building blocks with optical circulators and related control devices for constructing large rearrangeably nonblocking N x,N WXC's, The P-type building block is composed of certain "parallel" FBG-element chains placed between the control devices of two large mechanical optical switches (OSW's), The S-type building block consists of a "series" of FBG elements and the control device of 2 x 2 OSW's, The nonswitched N-type building block includes a "series" of FBG elements with appropriate stepping motor or PZT control devices. All FBG elements, each with central wavelength corresponding to equally or unequally spaced WDM channel wavelengths, with high-reflectivity are required. Large N x N WXC structures, with minimum number of required constitutive elements, based on a three-stage Clos network are then constructed. We investigate their relevant characteristics, compare the required constitutive elements, and estimate the dimension limits for these WXC architectures. Other related issues such as capacity expansion, wavelength channel spacing, and multiwavelength amplification are also addressed.
Guest editorial: System-on-a-chip for multimedia systems
(2005-08-01)
Chen, YK
;
Wen, SKA
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Lee, CY
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Hybrid 10-Gb/s, 2.5-Gb/s, 64-QAM, and AM-VSB high-capacity wavelength-division-multiplexing transport systems using SMF and LEAF fibers
(2002-02-01)
Lee, CC
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Chen, YK
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Chang, CH
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Feng, KM
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Tzeng, SL
A four-wavelength high-capacity hybrid wavelength-division-multiplexing (WDM) system separately over 100-km standard single-mode fiber and nonzero dispersion-shifted fiber of large effective area fiber is demonstrated. The WDM wavelengths contain one 10-Gb/s signal, one 2.5-Gb/s signal, one 64-quadrature amplitude modulator signal of 110 channels, and one amplitude module with vestigial sideband signal of 80 channels. Satisfaction of a huge variety of receiving requirements and reduction of fiber nonlinearities-induced degradations by controlling channel powers are also considered. Such a hybrid WDM system would be attractive for multiservice trunk applications in advanced transport systems for providing both CATV and telecommunication services.
Ip connectivity for gateway GPRS support node
(2005-02-01)
Chen, YK
;
Lin, YB
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交大名義發表
;
National Chiao Tung University
In the Universal Mobile Telecommunications System, the gateway GPRS support node (GGSN) provides IP connection between the mobile telecommunications network and external packet data networks (e.g., the Internet). Specifically, the GGSN exercises session management to transfer user packets between mobile stations and external data networks. In this article we focus on the GGSN functions for IP connection including access point name processing, IP address allocation, tunneling technologies, and QoS management. Based on our experience as a mobile operator, we give several examples to show how these functions can actually be implemented in a commercial mobile network.
Optimum configuration and design of 1480-nm pumped L-band gain-flattened EDFA using conventional erbium-doped fiber
(2000-09-01)
Liang, TC
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Chen, YK
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Su, JH
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Tzeng, WH
;
Hu, C
We theoretically investigate optimum configurations of 1480-pumped L-band (1570-1610 nm) gain-flattened erbium-doped fiber amplifier (EDFA), using conventional erbium-doped fiber, for multi-wavelength wavelength division multiplexing (WDM) systems. The design criterion of L-band EDFA is to achieve the highest channel output power while keeping the differential channel output power to be less than or equal to 0.7 dB among 32 digital baseband channels with low channel noise figure of less than or equal to 5.5 dB. A total of nine L-band EDFA configurations are examined and compared. These configurations considered include the dual-forward, dual-backward, and different bi-directional pumping schemes, each with and without the midway optical isolator. Among all configurations, we find that the pump-passed case in forward-and-backward pumping scheme is the best amplifier configuration to offer the highest channel output power with good channel gain uniformity and moderate low noise figure. In addition, the tolerance of the ratio of first-staged EDF length to the total EDF length, and the effects of optical isolation of midway isolator, and pump power degradation on the characteristics of the best configuration are also examined. This investigation provides the EDFA configuration selection for multi-wavelength WDM L-band lightwave systems. (C) 2000 Published by Elsevier Science B.V.
Optimum gain-equalised configuration of wideband erbium-doped fibre amplifier using inter-stage samarium-doped fibre and midway isolator
(1996-11-07)
Chen, YK
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Liaw, SK
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光電工程學系
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Department of Photonics
The optimum gain-equalised configuration for the erbium-doped fibre amplifier (EDFA) using a samarium-doped fibre (SDF) is investigated. The dual-pumping scheme with inter-stage SDF and midway isolator was found to be the optimum scheme for obtaining flattened high spectral gain with variation of less than or equal to +/-0.7dB and with a low noise figure of less than or equal to 5.6dB within the 1530-1560nm range. This amplifier is suitable for multiwavelength transmission systems containing EDFA cascades.
Passive gain-equalized wide-band erbium-doped fiber amplifier using samarium-doped fiber
(1996-07-01)
Liaw, SK
;
Chen, YK
;
光電工程學系
;
Department of Photonics
A passive gain-equalization technique of erbium-doped fiber amplifier (EDFA) using a samarium-doped fiber to obtain wide-band flattened gain operation is reported, In the wavelength range from 1529-1559-nm, small inter-channel gain variations can be achieved, This simple technique is suitable for multiwavelength wide-band in-line-amplifier cascaded transmission applications.
Passive gain-equalized wide-band erbium-doped fiber amplifier using samarium-doped fiber
(1996-07-01)
Liaw, SK
;
Chen, YK
;
光電工程學系
;
Department of Photonics
A passive gain-equalization technique of erbium-doped fiber amplifier (EDFA) using a samarium-doped fiber to obtain wide-band flattened gain operation is reported, In the wavelength range from 1529-1559-nm, small inter-channel gain variations can be achieved, This simple technique is suitable for multiwavelength wide-band in-line-amplifier cascaded transmission applications.
Reconfigurable WDM add/drop multiplexer based on optical switches and fibre Bragg gratings
(1999-01-01)
Liaw, SK
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Ho, KP
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Chen, YK
;
Lee, CC
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光電工程學系
A reconfigurable wavelength-division-multiplexing (WDM) add/drop multiplexer (WADM) is constructed using optical switches (OSWS) and fibre Bragg gratings (FBGs). Selected one or two channel(s) can be added/dropped at the same multiplexer by properly controlling the optical switch pair and fibre Bragg grating arrangement. A four-channel system is experimentally demonstrated for a data rate of 2.5 Gb s(-1) and a single-mode fibre (SMF) distance of 100 km. A negligible maximum power penalty of only 0.3 dB is observed when compared with back-to-back transmission.
Reducing authentication signaling traffic in third- generation mobile network
(2003-05-01)
Lin, YB
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Chen, YK
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資訊工程學系
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Department of Computer Science
In universal mobile telecommunication system (UMTS), authentication functions are utilized to identify and authenticate a mobile station (MS) and validate the service request type to ensure that the user is authorized to use the particular network services. The authenticating parties are the authentication center (AuC) in the home network and the MS. In UMTS, the serving general packet radio service support node (SGSN) accesses the AuC to obtain the authentication data, and delegates the AuC to perform mutual authentication with the MS. Since the cost for accessing AuC is expensive, the SGSN may obtain an array of authentication vectors (AVs) at a time so that the number of accesses can be reduced. On the other hand, if the size K of the AV array is large, the AV array transmission from the AuC to the SGSN may be expensive. Thus, it is desirable to select an appropriate K value to minimize the authentication network signaling cost. We propose an analytic model to investigate the impact of K on the network signaling traffic, which is validated by simulation experiments. Then, we propose an automatic K-selection mechanism that dynamically selects the size of the AV array to reduce the network signaling cost. Our study indicates that the automatic K-selection mechanism effectively identifies appropriate size of the authentication vector array.
Single-longitudinal-mode fiber laser with a passive multiple-ring cavity and its application for video transmission
(1998-03-01)
Lee, CC
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Chen, YK
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Liaw, SK
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光電工程學系
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Department of Photonics
A single-longitudinal-mode erbium-doped fiber laser with a passive multiple-ring cavity (MRC) is proposed for the first time to the authors' knowledge. The laser is fundamentally structured by insertion of three different short ring cavities, which serve as mode filters, into the main cavity. When it is combined with a mode-restricting intracavity fiber Bragg grating, the MRC resonator ensures single-longitundinal-mode laser oscillation. The laser can successfully suppress side-mode frequencies of as much as 1 GHz and provide an output power of 23 mW with a side-mode suppression ratio of 51 dB at 1533 nm. The short-term linewidth of the laser output measured is similar to 2 kHz. The ability of this fiber laser to act as an AM transmitter source is also demonstrated. (C) 1998 Optical Society of America.
Thermal properties, miscibility and specific interactions in comparison of linear and star poly(methyl methacrylate) blend with phenolic
(2004-08-05)
Huang, CF
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Kuo, SW
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Lin, HC
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Chen, JK
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Chen, YK
A series of miscible linear and star poly(methyl methacrylate) (PMMA)/phenolic blends with different compositions have been prepared. T(g)s of both systems are negative derivation from the average values, implying that the self-association interaction is stronger than the inter-association interaction between linear or star PMMA with phenolic. The proton spin-lattice relaxation time in the rotating frame (T-1rho(H)) determined by high resolution solid state C-13 NMR indicates single composition dependent T-1rho(H) from all blends, implying a good miscibility with chain dynamics on a scale of 1-2 nm. However, T(1rho)(H)s of star PMMA/phenolic blends are relatively smaller than those of linear PMMA/phenolic blends, implying that the degree of homogeneity of star PMMA/phenolic blends is higher than those of linear PMMA/phenolic blends. According to FT-IR analyses, the above results can be rationalized that the hydrogen-bonding interaction of the star PMMA/phenolic blends is greater than the corresponding linear PMMA/phenolic blends. (C) 2004 Elsevier Ltd. All rights reserved.