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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

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Now showing 1 - 10 of 76

A web-based monitor and management system architecture for enterprise Virtual Private Network
(2005-01-01)
Chen, RS
;
Chang, CC
;
Yeh, SW
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
This research is based on the new network management technologies such as Policy-based Network Management, Mobile Agent, etc., to design a VPN monitor and management system architecture that is suitable for the enterprise use and contains high level management with low Network Traffic load. This system architecture integrates the monitor and management for both VPN devices and general network devices, such the feature makes enterprise can integrate the monitor and manage the VPN and Intranet at the same time and solve the problems caused by using the VPN. The results of this research provide a VPN system architecture for monitoring and managing the enterprises and establish a prototype for the enterprise VPN` monitor and management system.
Fiber-optic subcarrier multiplexed CDMA local-area networks for subband image transmission
(1996-12-01)
Chang, PR
;
Chang, CC
;
電信工程研究所
;
Institute of Communications Engineering
This paper investigates the application of subcarrier multiplexed code-division multiple-access (CDMA) techniques to image transmission over fiber-optic local-area networks (LAN's), In the hybrid scheme, CDMA is used to suppress the interference caused by the laser nonlinearity in the subcarrier multiplexing (SCM) fiber-optic communication systems, Likewise, the SCM scheme is able to increase the channel data rate of CDMA systems, This hybrid system combines the advantages of both schemes and is particularly well suited to subband coding that divides the image information into multiple parallel data streams using an analysis filter bank, each of which is transmitted via a unique subcarrier-code pair, where the spreading code and subcarrier frequency correspond to the image and one of its subbands, respectively, This hybrid scheme also allows more than one image to be transmitted and be accessed simultaneously at the same channel bandwidth, in which each image is assigned a particular spreading code added to its digital data modulating the subcarrier. After transmission, each received signal is independently recovered at a high-Q surface acoustic wave (SAW) receiver with the matching subcarrier-code pair, Other concurrent signals are rejected by the SAW, Then, all the recovered subbands are reassembled by a synthesis filter bank into a close reproduction to the original image, In this paper, the image quality of subband image transmission via CDMA/SCM fiber-optic channels is evaluated and examined.
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.
Some properties of optimal Cartesian product files for orthogonal range queries
(1996-04-01)
Chou, AYH
;
Yang, WP
;
Chang, CC
;
資訊工程學系
;
Department of Computer Science
Cartesian product file (CPF) has bren proposed as a good multi-attribute file structure. Although designing an optimal CPF for partial match queries (PMQs) has been proven to be NP-hard, some useful properties have been studied for PMQs to help the work. However, a good CPF for PMQs may not be beneficial for orthogonal range queries (ORQs). Therefore, in this paper, we intend to study properties that help the design of a good CPF for ORQs. We found that the problem of designing the optimal CPF for ORQs is related to the problem of finding a minimal-f N-tuple. We will also show some theories of minimal-f N-tuples and develop a method for generating a minimal-f N-tuple. Finally, we will present some properties of the optimal CPF for ORQs from the theories of minimal-f N-tuples.
Authenticated encryption schemes with message linkage
(1996-05-27)
Hwang, SJ
;
Chang, CC
;
Yang, WP
;
資訊工程學系
;
Department of Computer Science
Authenticated encryption schemes need redundancy schemes to link up the message blocks; however, these redundancies increase communication costs. To construct links without increasing communication costs, we propose a general solution for all the authenticated encryption schemes based on the discrete logarithm problem. Because the computation cost to construct links is small, the improved scheme adopting our solution is almost as efficient as the original one, Moreover, by our solution, the recipient can easily determine the missing message blocks, and then acknowledge the sender to send only these blocks again. The communication cost will be also reduced. Adopting our solution, we also propose two new authenticated encryption schemes with message linkage.
Environment prediction for a mobile robot in a dynamic environment
(1997-12-01)
Chang, CC
;
Song, KT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The problem of navigating a mobile robot among moving obstacles is usually solved on the condition of knowing the velocity of obstacles. However, it is difficult to provide such information to a robot in real time. In this paper, we present an environment predictor that provides an estimate of future environment configuration by fusing multisensor data in real time. The predictor is implemented by an artificial neural network (ANN) trained using a relative-error-backpropagation (REBP) algorithm. The REBP algorithm enables the ANN to provide output data with a minimum relative error, which is better than conventional backpropagation (BP) algorithms in this prediction application. The mobile robot can, therefore, respond to anticipated changes in the environment. The performance is verified by prediction simulation and navigation experiments.
Broadcasting secrets in communication networks
(1998-03-01)
Chang, CC
;
Wu, TC
;
Yeh, YS
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
One property of a broadcast channel is that a single message broadcasted from an originator may be received simultaneously by several recipients in communication links. Based on the Chinese remainder theorem (CRT), we propose a new secure broadcasting scheme to distribute different secrets in one single broadcasting transaction such that each of the secrets is dedicated to different authorized recipients. On receiving the ciphertext broadcasted by the originator, only authorized recipients can obtain and authenticate their dedicated secrets individually, while no secret is revealed to unauthorized recipients. In a single broadcasting transaction, each authorized recipient cannot know who are the other intended recipients for this transaction. Furthermore, the processes for decryption and authentication of the dedicated secret are performed through simple arithmetic computation, i.e., modular operations, hence it is suitable for the applications that the recipient has less computing power. We also show that the proposed scheme can withstand the attack on replaying a previously intercepted broadcasting message.
An accuracy enhancement algorithm for hierarchical radiosity
(1998-03-01)
Chang, CC
;
Shih, ZC
;
資訊工程學系
;
Department of Computer Science
In this research, we propose an algorithm to enhance the accuracy of the hierarchical radiosity. The proposed approach particularly creates links on the hierarchy in a bottom-up fashion according to both a user-specified error tolerance and the minimum patch area. It differs from the original hierarchical method that creates the links in a top-down manner. In our approach, the upper-level patches have more accurate estimates of the kernel. More accurate error bounds can be obtained for the upper-level patches. These error bounds make the creation of links on the hierarchy more accurate. Furthermore, more accurate form factors can also be obtained for the upper-level patches. Thus, we enhance the accuracy of hierarchical radiosity. (C) 1998 Elsevier Science Ltd. All rights reserved.
An encryption/multisignature scheme with specified receiving groups
(1998-03-01)
Hwang, SJ
;
Chen, CY
;
Chang, CC
;
資訊工程學系
;
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.
Tighter error bounds and weighted error metrics for hierarchical radiosity
(1998-04-01)
Chang, CC
;
Shih, ZC
;
資訊工程學系
;
Department of Computer Science
In this paper we first derive a tighter error bound on form factors as a subdivision criterion for the hierarchical radiosity algorithm. Such an error bound can reduce more unnecessary links and improve the performance of the hierarchical radiosity algorithm to meet a user-specified error tolerance. We then propose a weighted error metric in form factor computation such that more effort is automatically applied to shadow boundaries. Evaluating form factors along shadow boundaries with a higher degree of precision should enhance the quality of human perception. Using the proposed tighter error bound on the weighted error metric, we not only improve the performance but also increase the accuracy of the hierarchical radiosity algorithm. (C) 1998 John Whey & Sons, Ltd.

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