Browsing by Author "Chang, TH"

Now showing 1 - 13 of 13

A structural process toward a sustainable ITS deployment
(2000)
Mao, CK
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Chang, TH
;
Hu, SR
;
經營管理研究所
;
Institute of Business and Management
Intelligent Transportation Systems (ITS) are the enhanced and integrated systems that employed advanced information and communication technologies to the operations of existing transportation systems. To achieve the goals of ITS, an ITS framework that guides the development directions and deployment strategies is a crucial component. Herein, a structural process that formulates a conceptual framework has been proposed. This conceptual framework basically identifies the crucial areas needed for the successful deployment of ITS. Based on the framework, a bunch of short-term action plans has been formulated and conducted. Also, future deployment prospects for ITS and the corresponding deployment time schedule are provided. It is aimed to not only provide the minimum required intelligent transportation infrastructure for various transportation modes, but also preserve an endurable and livable environment for next generations.
Automatic Chinese unknown word extraction using small-corpus-based method
(2003)
Chang, TH
;
Lee, CH
;
資訊工程學系
;
Department of Computer Science
Chinese unknown word extraction is an important problem for Chinese language processing. There are troublesome difficulties in the problem. First, almost any Chinese character can either represent a word or be a part of other words. Secondly, there is no blank between Chinese words for identifying the boundaries. Although some approaches have been proposed, there are some drawbacks in these methods. In this paper, we present and develop a method to extract Chinese unknown words more efficiently and precisely. It retains efficiency and accuracy even though the size of document set is small for training. It can also extract the unknown words occur rarely. Based on these advantages, it is very practical for real applications.
Did your efforts really win customers' satisfaction?
(2003)
Chien, TK
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Chang, TH
;
Su, CT
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工業工程與管理學系
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Department of Industrial Engineering and Management
The national customer satisfaction index (NCSI) shows that these indices compare and estimate the competitiveness and financial benefits for countries and industries. However, general enterprise uses the concepts of NCSI deficiently in the practice of CS activities. This paper will express the latent variables in the NCSI models of different countries in order to highlight all the efforts companies have made in promoting CS activities to win customers' satisfaction and loyalty. Through the successful experience of a Taiwanese company, the relationship between the NCSI and the various concrete issues within the CS program is compared. Also, this article proposes the concept of a "matching rate" to show how the necessary concrete issues of all CS activities must link with the latent variables of NCSI. Finally, the managerial implications of the matching rate are explained, and it is suggested how an enterprise can use the rate to draw up the strategy of the CS program.
Dual-band sigma-delta modulator for wideband receiver applications
(2004-02-01)
Chiang, JS
;
Chou, PC
;
Chang, TH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This work presents a new sigma-delta modulator (SDM) architecture for a wide bandwidth receiver. This architecture contains dualbandwidth for W-CDMA and GSM system applications. Low-distortion swing-suppressing SDM and interpolative SDM cascaded units are used together. Using the low-distortion swing-suppressing technique, the resolution can be improved even under non-linearity effects. The interpolative SDM extends the signal bandwidth and represses the high-band noise. The SDM used in the W-CDMA and GSM applications was designed and simulated using 0.25-mum 1P5M CMOS technology. The simulated peak SNDR of W-CDMA and GSM are 72/70 dB and 82/84 dB in Low-IF/Zero-IF standards.
Dynamic range improvement of multistage multibit Sigma Delta modulator for low oversampling ratios
(2005-02-01)
Chang, TH
;
Dung, LR
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents an improved architecture of the multistage multibit sigma-delta modulators (EAMs) for wide-band applications. Our approach is based on two resonator topologies, high-Q cascade-of-resonator-with-feedforward (HQCRFF) and low-Q cascade-of-integrator-with-feedforward (LQCEFF). Because of in-band zeros introduced by internal loop filters, the proposed architecture enhances the suppression of the in-band quantization noise at a low OSR. The HQCRFF-based modulator with single-bit quantizer has two modes of operation, modulation and oscillation. When the HQCRFF-based modulator is operating in oscillation mode, the feedback path from the quantizer output to the input summing node is disabled and hence the modulator output is free of the quantization noise terms. Although operating in oscillation mode is not allowed for single-stage SigmaDeltaM, the oscillation of HQCRFF-based modulator can improve dynamic range (DR) of the multistage (MASH) SigmaDeltaM. The key to improving DR is to use HQCRFF-based modulator in the first stage and have the first stage oscillated. When the first stage oscillates, the coarse quantization noise vanishes and hence circuit nonidealities, such as finite op-amp gain and capacitor mismatching, do not cause leakage quantization noise problem. According to theoretical and numerical analysis, the proposed MASH architecture can inherently have wide DR without using additional calibration techniques.
Finding multiple possible critical paths using fuzzy PERT
(2001-12-01)
Chen, SM
;
Chang, TH
;
資訊工程學系
;
Department of Computer Science
Program evaluation and review techniques (PERT) is an efficient tool for large project management. In actual project control decisions, PERT has successfully been applied to business management, industry production, project scheduling control, logistics support, etc. However, classical PERT requires a crisp duration time representation for each activity. This requirement is often difficult for the decision-makers due to the fact that they usually can not estimate these values precisely. In recent years, some fuzzy PERT methods have been proposed based on fuzzy set theory for project management. However, there is a drawback in the existing fuzzy PERT methods, i.e., sometimes they maybe cannot rind a critical path in a fuzzy project network. In this paper, we propose a fuzzy PERT algorithm to find multiple possible critical paths in a fuzzy project network, where the duration time of each activity in a fuzzy project network is represented by a fuzzy number. The proposed algorithm can overcome the drawback of the existing fuzzy PERT methods.
Low distortion and swing suppression sigma-delta modulator with extended dynamic range scheme
(2005-11-01)
Chiang, JS
;
Chang, TH
;
Chou, PC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This work presents a new low distortion and swing suppression second order sigma-delta modulator with extended dynamic range scheme. The proposed modulator is based on the dual-quantizer architecture and can effectively extend the dynamic range by only adding two simple digital filters in the digital circuit. The techniques of low distortion and swing suppression integrator designs are also employed in the new architecture. Accordingly, this new architecture can improve the circuitry nonlinearity, and the in-band noise can be significantly suppressed to achieve a high resolution in mid or wide bandwidth applications. A second order SDM for Bluetooth application with bandwidth of 500 KHz and sampling frequency of 40 MHz was designed and implemented. The peak SNDR of the experimental SDM is 78 dB.
On improving dynamic range of wideband multistage Sigma Delta modulator using nonlinear oscillation
(2005)
Chang, TH
;
Dung, LR
;
Guo, JY
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents an improved architecture of the multistage (MASH) multibit sigma-delta modulators (Sigma Delta Ms). The architecture can be immune to circuit nonidealities over a large portion of input range when oversampling ratio (OSR) is low, and hence the dynamic range (DR) can be improved. Our approach is based on two resonator topologies, high-Q cascade-of-resonator-with-feedforward (HQCRFF) and low-Q cascade-of-integrator-with-feedforward (LQCIFF). The key to improving DR is to use HQCRFF-based single-bit structure in the first stage and have the first stage oscillated. When the first stage oscillates, the coarse quantization noise vanishes and hence circuit nonidealities, such as finite op-amp gain and capacitor mismatching, do not cause leakage quantization noise problem. In addition, because of the in-band zeros introduced by the resonators, the proposed architecture enhances the suppression of the in-band quantization noise for wideband applications. As the results of simulation, the proposed MASH architecture can inherently have wide DR without using additional calibration techniques.
On reducing leakage quantization noise of multistage Sigma Delta modulator using nonlinear oscillation
(2005)
Chang, TH
;
Dung, LR
;
Guo, JY
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents an improved architecture of the multistage (MASH) multibit sigma-delta modulators (Sigma Delta Ms). The architecture can be immune to circuit nonidealities over a large portion of input range when oversampling ratio (OSR) is low, and hence the dynamic range (DR) can be improved. Our approach is based on two resonator topologies, high-Q cascade-of-resonator-with-feedforward (HQCRFF) and low-Q cascade-of-integrator-with-feedforward (LQCIFF). The key to improving DR is to use HQCRFF-based single-bit structure in the first stage and have the first stage oscillated. When the first stage oscillates, the coarse quantization noise vanishes and hence circuit nonidealities, such as finite op-amp gain and capacitor mismatching, do not cause leakage quantization noise problem. In addition, because of the in-band zeros introduced by the resonators, the proposed architecture enhances the suppression of the in-band quantization noise for wideband applications. As the results of simulation, the proposed MASH architecture can inherently have wide DR without using additional calibration techniques.
Resonator-based multi-stage Sigma Delta modulator for wideband applications with improved dynamic range
(2004-05-27)
Chang, TH
;
Dung, LR
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A new design methodology for wideband, multi-stage, multi-bit YEA modulators (SigmaDeltaMs) with improved dynamic range, is presented. The key to improving dynamic range is to have the first stage oscillated, then the coarse quantisation noise vanishes and hence circuit nonlinearities do not cause a leakage quantisation noise problem. Based on the proposed methodology, a fourth-order four-bit SigmaDeltaM can achieve the dynamic range of 80 dB at the OSR of 8 without using additional calibration techniques.
Simultaneous quality improvement of tunneling- and interpoly-oxides of nonvolatile memory devices by NH3 and N2O nitridation
(2003-01-01)
Chao, TS
;
Chang, TH
;
電子物理學系
;
Department of Electrophysics
In this paper, we found the nitridation on the interpoly-oxide with NH3 and N2O processes can simultaneously improve the quality of both tunneling oxide and interpoly-oxide. Three types of poly-Si for floating gate are investigated. We found in-situ doped poly -Si shows the best performance in terms of breakdown filed, charge to breakdown (Q(BD)) and trapping rate The Q(BD) of interpoly-oxide can be reached as high as 35 C/cm(2). This scheme is very promising for nonvolatile memory devices.
Simultaneous quality improvement of tunneling- and interpoly-oxides of nonvolatile memory devices by NH3 and N2O nitridation
(2003-11-01)
Chao, TS
;
Chang, TH
;
電子物理學系
;
Department of Electrophysics
This brief presents a new nitridation process on floating poly-Si gate to improve the quality of both tunneling oxide and interpoly-oxide of nonvolatile memories. Three types of poly-Si for a floating gate have been investigated. We found in-situ doped poly-Si shows the best performance in terms of breakdown field, charge-to-breakdown (Q(BD)) and trapping rate. The Q(BD) of interpoly-oxide can be reached as high as 35 C/cm(2). This scheme is very promising for nonvolatile memory devices.
Topic segmentation for short texts
(2003)
Chang, TH
;
Lee, CH
;
資訊工程學系
;
Department of Computer Science
Topic segmentation, which aims to find the boundaries between topic blocks in a text, is an important task for semantic analysis of texts. Although different solutions have been proposed for the task, many limitations and difficulties exist in the approaches. In particular most of the methods do not work well for such case as short texts, internet news and student's writings. In this paper, we focus on the short texts and present a method for topic segmentation. It can overcome the limitations in previous works. In preliminary experiments, the method show the accuracy of topic segmentation is increased effectively.