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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Electronics and Telecommunications Research Institute
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Volume & Issues
Volume 22, Issue 4 - Dec 2000
Volume 22, Issue 3 - Sep 2000
Volume 22, Issue 2 - Jun 2000
Volume 22, Issue 1 - Mar 2000
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Delay-Constrained Bottleneck Location Estimator and Its Application to Scalable Multicasting
Kim, Sang-Bum ; Youn, Chan-Hyun ;
ETRI Journal, volume 22, issue 4, 2000, Pages 1~1
Designing a reliable multicast-based network that scales to the size of a multicast group member is difficult because of the diversity of user demands. The loss inferences of internal nodes by end-to-end measurements do not require the use of complete statistics because of the use of maximum likelihood estimation. These schemes are very efficient and the inferred value converges fast to its true value. In the theoretical analysis, internal delay estimation is possible but the analysis is very complex due to the continuity property of the delay. In this paper, we propose the use of a bottleneck location estimator. This can overcome the analytical difficulty of the delay estimation using the power spectrum of the packet interarrival time as the performance metric. Both theoretical analysis and simulation results show that the proposed scheme can be used for bottleneck location inference of internal links in scalable multicasting.
On-Chip Multiprocessor with Simultaneous Multithreading
Park, Kyoung ; Choi, Sung-Hoon ; Chung, Yong-Wha ; Hahn, Woo-Jong ; Yoon, Suk-Han ;
ETRI Journal, volume 22, issue 4, 2000, Pages 13~13
As more transistors are integrated onto bigger die, an on-chip multiprocessor will become a promising alternative to the superscalar microprocessor that dominates today's microprocessor marketplace. This paper describes key parts of a new on-chip multiprocessor, called Raptor, which is composed of four 2-way superscalar processor cores and one graphic co-processor. To obtain performance characteristics of Raptor, a program-driven simulator and its programming environment were developed. The simulation results showed that Raptor can exploit thread level parallelism effectively and offer a promising architecture for future on-chip multi-processor designs.
Provably Secure Length-Saving Public-Key Encryption Scheme under the Computational Diffie-Hellman Assumption
Baek, Joon-Sang ; Lee, Byoung-Cheon ; Kim, Kwang-Jo ;
ETRI Journal, volume 22, issue 4, 2000, Pages 25~25
Design of secure and efficient public-key encryption schemes under weaker computational assumptions has been regarded as an important and challenging task. As far as ElGamal-type encryption schemes are concerned, some variants of the original ElGamal encryption scheme based on weaker computational assumption have been proposed: Although security of the ElGamal variant of Fujisaki-Okamoto public -key encryption scheme and Cramer and Shoup's encryption scheme is based on the Decisional Diffie-Hellman Assumption (DDH-A), security of the recent Pointcheval's ElGamal encryption variant is based on the Computational Diffie-Hellman Assumption (CDH-A), which is known to be weaker than DDH-A. In this paper, we propose new ElGamal encryption variants whose security is based on CDH-A and the Elliptic Curve Computational Diffie-Hellman Assumption (EC-CDH-A). Also, we show that the proposed variants are secure against the adaptive chosen-ciphertext attack in the random oracle model. An important feature of the proposed variants is length-efficiency which provides shorter ciphertexts than those of other schemes.
Adaptive Compensation Method Using the Prediction Algorithm for the Doppler Frequency Shift in the LEO Mobile Satellite Communication System
You, Moon-Hee ; Lee, Seong-Pal ; Han, Young-Yearl ;
ETRI Journal, volume 22, issue 4, 2000, Pages 32~32
In low earth orbit (LEO) satellite communication systems, more severe phase distortion due to Doppler shift is frequently detected in the received signal than in cases of geostationary earth orbit (GEO) satellite systems or terrestrial mobile systems. Therefore, an estimation of Doppler shift would be one of the most important factors to enhance performance of LEO satellite communication system. In this paper, a new adaptive Doppler compensation scheme using location information of a user terminal and satellite, as well as a weighting factor for the reduction of prediction error is proposed. The prediction performance of the proposed scheme is simulated in terms of the prediction accuracy and the cumulative density function of the prediction error, with considering the offset variation range of the initial input parameters in LEO satellite system. The simulation results showed that the proposed adaptive compensation algorithm has the better performance accuracy than Ali's method. From the simulation results, it is concluded the adaptive compensation algorithm is the most applicable method that can be applied to LEO satellite systems of a range of altitude between 1,000 km and 2,000 km for the general error tolerance level, M = 250 Hz.
Estimation and Prediction-Based Connection Admission Control in Broadband Satellite Systems
Jang, Yeong-Min ;
ETRI Journal, volume 22, issue 4, 2000, Pages 40~40
We apply a "sliding-window" Maximum Likelihood(ML) estimator to estimate traffic parameters On-Off source and develop a method for estimating stochastic predicted individual cell arrival rates. Based on these results, we propose a simple Connection Admission Control(CAC)scheme for delay sensitive services in broadband onboard packet switching satellite systems. The algorithms are motivated by the limited onboard satellite buffer, the large propagation delay, and low computational capabilities inherent in satellite communication systems. We develop an algorithm using the predicted individual cell loss ratio instead of using steady state cell loss ratios. We demonstrate the CAC benefits of this approach over using steady state cell loss ratios as well as predicted total cell loss ratios. We also derive the predictive saturation probability and the predictive cell loss ratio and use them to control the total number of connections. Predictive congestion control mechanisms allow a satellite network to operate in the optimum region of low delay and high throughput. This is different from the traditional reactive congestion control mechanism that allows the network to recover from the congested state. Numerical and simulation results obtained suggest that the proposed predictive scheme is a promising approach for real time CAC.
A New Venture Performance Model in the Korean Information and Telecommunications Industry
Park, Myeong-Cheol ; Lee, Sang-Woo ;
ETRI Journal, volume 22, issue 4, 2000, Pages 51~51
In this paper, we investigate on the determinants of new venture performance empirically and suggest a new venture performance model in the Korean Information and Telecommunications (IT) industry. A total of seven hypotheses is established and tested using a combination of factor analysis, cluster analysis, analysis of variance, and correlation analysis. Ninety-two sample ventures in the Korean IT industry were investigated and analyzed to test hypotheses. We found that new ventures performance depends on their environment, strategy, internal resources factors, and, most importantly, two-way and three-way interactions of these factors. These findings could be interpreted as supporting the general strategy theory that when environment and internal resources and fitted, performance might be maximized and, further, strategy is the means that make internal resources and environment fit. The venture performance model presented in this paper can explain how new ventures achieve their successes. The strategic implications to the venture firms are also discussed.