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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 21, Issue 4 - Dec 1999
Volume 21, Issue 3 - Sep 1999
Volume 21, Issue 2 - Jun 1999
Volume 21, Issue 1 - Mar 1999
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Thick Metal CMOS Technology on High Resistivity Substrate and Its Application to Monolithic L-band CMOS LNAs
Kim, Cheon-Soo ; Park, Min ; Kim, Chung-Hwan ; Yu, Hyun-Kyu ; Cho, Han-Jin ;
ETRI Journal, volume 21, issue 4, 1999, Pages 1~1
Thick metal 0.8
CMOS technology on high resistivity substrate(RF CMOS technology) is demonstrated for the L-band RF IC applications, and we successfully implemented it to the monolithic 900 MHz and 1.9 GHz CMOS LNAs for the first time. To enhance the performance of the RF circuits, MOSFET layout was optimized for high frequency operation and inductor quality was improved by modifying the technology. The fabricated 1.9 GHz LNA shows a gain of 15.2 dB and a NF of 2.8 dB at DC consumption current of 15mA that is an excellent noise performance compared with the offchip matched 1.9 GHz CMOS LNAs. The 900 MHz LNA shows a high gain of 19 dB and NF of 3.2 dB despite of the performance degradation due to the integrating of a 26 nH inductor for input match. The proposed RF CMOS technology is a compatibel process for analog CMOS ICs, and the monolithic LNAs employing the technology show a good and uniform RF performance in a five inch wafer.
Design and Configuration of Reconfigurable ATM Networks with Unreliable Links
Lee, Jong-Hyup ;
ETRI Journal, volume 21, issue 4, 1999, Pages 9~9
This paper considers a problem of configuring both physical backbone and logical virtual path (VP) networks in a reconfigurable asynchronous transfer mode (ATM) network where links are subject to failures. The objective is to determine jointly the VP assignment, the capacity assignment of physical links and the bandwidth allocation of VPs, and the routing assignment of traffic demand at least cost. The network cost includes backbone link capacity expansion cost and penalty cost for not satisfying the maximum throughput of the traffic due to link failures or insufficient link capacities. The problem is formulated as a zero-one non-linear mixed integer programming problem, for which an effective solution procedure is developed by using a Lagrangean relaxation technique for finding a lower bound and a heuristic method exploited for improving the upper bound of any intermediate solution. The solution procedure is tested for its effectiveness with various numerical examples.
Performance Benefits of Virtual Path Tunneling for Control and Management Flows in the Broadband ATM Network
Choi, Jun-Kyun ; Kim, Soo-Hyung ; Kim, Nam ; Sohn, Sung-Won ; Choi, Mun-Kee ;
ETRI Journal, volume 21, issue 4, 1999, Pages 23~23
In this paper, we analyze the performance benefits of broadband ATM networks when the call control and management flows are separated from user data flows. The virtual path tunneling concept for control and management flows are applied to the same physical ATM networks. The behaviors of channel throughput and transfer delay are analyzed. It results that the proposed virtual short-cut paths can maintain the network being stable with acceptable bandwidth. They are very useful to provide the stable control and management capabilities for Internet and mobile applications in the broadband ATM networks. In our numerical results, the effective throughputs of the proposed virtual shout-ut channel are about three times than those of end-to-end user data channels with hop distances of 10, and about two times than those with hop distance of 5 when the link blocking probability increases to 0.1. It concludes that the effective channel bandwidth are greatly reduced down while physical links are not stable and user traffic flows are occasionally overflowed.
The Performance Improvement of a Multicarrier DS-CDMA System Using both Time-Diversity and Frequency Offset
Kim, Ki-Doo ; Oh, Jung-Hun ; Milstein, Laurence B. ;
ETRI Journal, volume 21, issue 4, 1999, Pages 29~29
In this paper, we show the robustness of a proposed system using both a frequency diversity and a time diversity effect when the channel assumptions are relaxed such that all sub-bands are not independent fading. We take time-repetition coding with interleaving such that the repetition code symbols are spaced sufficiently far apart to guarantee time diversity. We also incorporate offset multicarriers into a proposed multicarrier DS-CDMA system in a different way compared to that of  to reduce the total multiple access interference. When we take a convolutional encoder instead of a time-repetition encoder, and again use both time diversity and frequency offset, then we can obtain the significant performance gain.
An Application of Canonical Correlation Analysis Technique to Land Cover Classification of LANDSAT Images
Lee, Jong-Hun ; Park, Min-Ho ; Kim, Yong-Il ;
ETRI Journal, volume 21, issue 4, 1999, Pages 41~41
This research is an attempt to obtain more accurate land cover information from LANDSAT images. Canonical correlation analysis, which has not been widely used in the image classification community, was applied to the classification of a LANDSAT images. It was found that it is easy to select training areas on the classification using canonical correlation analysis in comparison with the maximum likelihood classifier of
software. In other words, the selected positions of training areas hardly affect the classification results using canonical correlation analysis. when the same training areas are used, the mapping accuracy of the canonical correlation classification results compared with the ground truth data is not lower than that of the maximum likelihood classifier. The kappa analysis for the canonical correlation classifier and the maximum likelihood classifier showed that the two methods are alike in classification accuracy. However, the canonical correlation classifier has better points than the maximum likelihood classifier in classification characteristics. Therefore, the classification using canonical correlation analysis applied in this research is effective for the extraction of land cover information from LANDSAT images and will be able to be put to practical use.
Modeling and Interoperability Test Case Generation of a Real-Time QoS Monitoring Protocol
Chin, Byoung-Moon ; Kim, Sung-Un ; Kang, Sung-Won ; Park, Chee-Hang ;
ETRI Journal, volume 21, issue 4, 1999, Pages 52~52
QoS monitoring is a kind of real-time systems which allows each level of the system to track the ongoing QoS levels achieved by the lower network layers. For these systems, real-time communications between corresponding transport protocol objects is essential for their correct behavior. When two or more entities are employed to perform a certain task as in the case of communication protocols, the capability to do so is called interoperability and considered as the essential aspect of correctness of communication systems. This paper describes a formal approach on modeling and interoperability test case generation of a real-time QoS monitoring protocol. For this, we specify the behavior of flow monitoring of transport layer QoS protocol, i.e., METS protocol, which is proposed to address QoS from an end-to-end's point of view, based on QoS architecture model which includes ATM net work in lower layers. We use a real-time Input/Output finite State Machine to model the behavior of real-time flow monitoring over time. From the modeled real-time I/OFSM, we generate interoperability test cases to check the correctness of METS protocol's flow monitoring behaviors for two end systems. A new approach to efficient interoperability testing is described and the method of interoperability test cases generation is shown with the example of METS protocol's flow monitoring. The current TTCN is not appropriate for testing real-time and multimedia systems. Because test events in TTCN are for message-based system and not for stream-based systems, the real-time in TTCN can only be approximated. This paper also proposes the notation of real-time Abstract Test Suite by means of real-time extension of TTCN. This approach gives the advantages that only a few syntactical changes are necessary, and TTCN and real-time TTCN are compatible. This formal approach on interoperability testing can be applied to the real-time protocols related to IMT-2000, B-ISDN and real-time systems.
An Improved Calculation Model for Analysis of  InGaAs/GaAs Strained Piezoelectric Superlattices
Kim, Byoung-Whi ; Yoo, Jae-Hoon ; Kim, Soo-Hyung ;
ETRI Journal, volume 21, issue 4, 1999, Pages 65~65
We present a calculation model for an improved quantitative theoretical analysis of electronic and optical properties of strained-piezoelectric InGaAs/GaAs superlattices (SLs). The model includes a full band-coupling between the four important energy bands: conduction, heavy, light, and spin split-off valence bands. The interactions between these and higher lying bands are treated by the k
p perturbation method. The model takes into account the differences in the band and strain parameters of constituent materials of the heterostructures by transforming it into an SL potential in the larger band-gap material region. It self-consistently solves an
equation and the Hartree and exchange-correlation potential equations through the variational procedure proposed recently by the present first author and applied to calculate optical matrix elements and spontaneous emission rates. The model can be used to further elucidate the recent theoretical results and experimental observations of interesting properties of this type of quantum well and SL structures, including screening of piezoelectric field and its resultant optical nonlinearities for use in optoelectronic devices.
Correlations between Users' Characteristics and Preferred Features of Web-Based OPAC Evaluation
Kim, Hee-Sop ; Chung, Hyun-Soo ; Hong, Gi-Chai ; Moon, Byung-Ju ; Park, Chee-Hang ;
ETRI Journal, volume 21, issue 4, 1999, Pages 83~83
This paper examines the correlations between user characteristics and their perferences for two selected features of Web-based OPAC systems. User characteristics identified in this study were age, gender, educational status, computer skills and OPAC experience. Usability features included interaction styles, character and image on screen, browsing and navigating style, screen layout, and ease of learning, whereas availability features attended to availability of information, quality of information and up-to-date information. Individual variables and features are described, and the correlation between the variables and the features are explored using Pearson's correlation coefficient(r). Although based on a small-scale sample survey, a considerably large number of statistically significant correlations were found between the users' characteristics and the selected evaluation features of interactive Web-based OPACs. From these observations, it seems to be suitable to recommend that system designers should make a more considered appraisal of the users' demographic characteristics in the design of the new generation of OPAC such as in user-tailored interactive Web-based OPAC systems.