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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 25, Issue 6 - Dec 2003
Volume 25, Issue 5 - Oct 2003
Volume 25, Issue 4 - Aug 2003
Volume 25, Issue 3 - Jun 2003
Volume 25, Issue 2 - Apr 2003
Volume 25, Issue 1 - Feb 2003
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Improving Efficiency of Timeslot Assignment for Non-realtime Data in a DVB-RCS Return Link: Modeling and Algorithm
Lee, Ki-Dong ; Cho, Yong-Hoon ; Lee, Ho-Jin ; Oh, Deock-Gil ;
ETRI Journal, volume 25, issue 4, 2003, Pages 211~211
This paper presents a dynamic resource allocation algorithm with multi-frequency time-division multiple access for the return link of interactive satellite multimedia networks such as digital video broadcasting return channel via satellite systems. The proposed timeslot assignment algorithm, called the very efficient dynamic timeslot assignment (VEDTA) algorithm, gives an optimal assignment plan within a very short period. The optimality and computational efficiency of this algorithm demonstrate that it will be useful in field applications.
English Syntactic Disambiguation Using Parser's Ambiguity Type Information
Lee, Jae-Won ; Kim, Sung-Dong ; Chae, Jin-Seok ; Lee, Jong-Woo ; Kim, Do-Hyung ;
ETRI Journal, volume 25, issue 4, 2003, Pages 219~219
This paper describes a rule-based approach for syntactic disambiguation used by the English sentence parser in E-TRAN 2001, an English-Korean machine translation system. We propose Parser's Ambiguity Type Information (PATI) to automatically identify the types of ambiguities observed in competing candidate trees produced by the parser and synthesize the types into a formal representation. PATI provides an efficient way of encoding knowledge into grammar rules and calculating rule preference scores from a relatively small training corpus. In the overall scoring scheme for sorting the candidate trees, the rule preference scores are combined with other preference functions that are based on statistical information. We compare the enhanced grammar with the initial one in terms of the amount of ambiguity. The experimental results show that the rule preference scores could significantly increase the accuracy of ambiguity resolution.
Linear Diversity Analysis for M-ary Square Quadrature Amplitude Modulation over Nakagami Fading Channels
Yoon, Dong-Weon ; Chang, Dae-Ig ; Kim, Nae-Soo ; Woo, Hoon-Shik ;
ETRI Journal, volume 25, issue 4, 2003, Pages 231~231
We derive and analyze the exact closed-form expression for the average bit error probability (BEP) of M-ary square quadrature amplitude modulation (QAM) for diversity reception in frequency-nonselective Nakagami fading. A maximal ratio combining (MRC) diversity technique with independent or correlated fading cases are considered. Numerical results demonstrate error performance improvement with the use of MRC diversity reception. The presented new expressions offer a convenient way to evaluate the performance of M-ary square QAM with an MRC diversity combiner for various cases of practical interest.
Performance Analysis of a Discrete-Time Two-Phase Queueing System
Kim, Tae-Sung ; Chang, Seok-Ho ; Chae, Kyung-Chul ;
ETRI Journal, volume 25, issue 4, 2003, Pages 238~238
This paper introduces the modeling and analysis of a discrete-time, two-phase queueing system for both exhaustive batch service and gated batch service. Packets arrive at the system according to a Bernoulli process and receive batch service in the first phase and individual services in the second phase. We derive the probability generating function (PGF) of the system size and show that it is decomposed into two PGFs, one of which is the PGF of the system size in the standard discrete-time Geo/G/1 queue without vacations. We also present the PGF of the sojourn time. Based on these PGFs, we present useful performance measures, such as the mean number of packets in the system and the mean sojourn time of a packet.
Excimer Laser-Assisted In Situ Phosphorus Doped
Bae, Ji-Cheul ; Lee, Young-Jae ;
ETRI Journal, volume 25, issue 4, 2003, Pages 247~247
This paper presents results from experiments on laser-annealed SiGe-selective epitaxial growth (LA-SiGe-SEG). The SiGe-SEG technology is attractive for devices that require a low band gap and high mobility. However, it is difficult to make such devices because the SiGe and the highly doped region in the SiGe layer limit the thermal budget. This results in leakage and transient enhanced diffusion. To solve these problems, we grew in situ doped SiGe SEG film and annealed it on an XMR5121 high power XeCl excimer laser system. We successfully demonstrated this LA-SiGe-SEG technique with highly doped Ge and an ultra shallow junction on p-type Si (100). Analyzing the doping profiles of phosphorus, Ge compositions, surface morphology, and electric characteristics, we confirmed that the LA-SiGe-SEG technology is suitable for fabricating high-speed, low-power devices.
Preparation and Holographic Recording of Diarylethene-Doped Photochromic Films
Kim, Eun-Kyoung ; Park, Ji-Young ; Cho, Song-Yun ; Kim, Nam ; Kim, Jung-Hoi ;
ETRI Journal, volume 25, issue 4, 2003, Pages 253~253
This study investigated the photochromic properties and characterization of acetyl-substituted diarylethene (DAMBTF6)-doped fluoroacrylates media for holographic storage. For the rewritable holographic recording media, we prepared photochromic polymer films using an acrylate matrix by simple photocuring methods. Switching light sources from a visible (532 nm) to an ultraviolet (365 nm) produced transparent films that changed from pale yellow to red. Holographic recording was performed on the photochromic films by two interfering collimated plane wave beams. Excitation with a visible or ultraviolet light completely erased the records, and the film was rewritable either by 532 nm laser or by 325 nm laser within 2 seconds. Images were recorded onto a pixelated spatial light modulator with rectangular pixel apertures and reconstructed on the photochromic films to show recovery of the original images with high resolution.
Determinants of Corporate R&D Investment: An Empirical Study Comparing Korea's IT Industry with Its Non-IT Industry
Lee, Myeong-Ho ; Hwang, In-Jeong ;
ETRI Journal, volume 25, issue 4, 2003, Pages 258~258
In our study, we extracted the market, finance, and government factors determining R&D investment of individual firms in the IT industry in Korea. We collected the financial data of 515 individual firms belonging to IT and non-IT industries between 1980 and 1999 from the Korea Investors Service's database and investigated the empirical relationship between the factors using an ordinary regression model, a fixed effects model, and a random effects model. The main findings of our study are as follows: i) The Herfindahl Index variable representing the degree of market concentration is statistically insignificant in explaining R&D expenditures in the IT manufacturing industry. ii) Assets, which is used as a proxy variable for firm size, have a positive and statistically significant coefficient. These two results suggest that the Schumpeterian Hypothesis may be only partially applied to the IT manufacturing industry in Korea. iii) The dividend variable has a negative value and is statistically significant, indicating that a tendency of high dividends can restrict the internal cash flow for R&D investment. iv) The sales variable representing growth potential shows a positive coefficient. v) The subsidy as a proxy variable for governmental R&D promotion policies is positively correlated with R&D expenditure. This suggests that government policy has played a significant role in promoting R&D activities of IT firms in Korea since 1980. vi) Using a dummy variable, we verified that firms reduced their R&D investments to secure sufficient liquidity under the restructuring pressure during Korea's 1998 and 1999 economic crisis.
Precision Molding of Polymeric Multi-Channel Optical Interconnection Devices Considering the Coefficient of Thermal Expansion of the Materials
Ahn, Seung-Ho ; Han, Sang-Pil ; Choi, Choon-Gi ; Jeong, Myung-Yung ;
ETRI Journal, volume 25, issue 4, 2003, Pages 266~266
Polymeric multi-channel optical interconnection devices that are usually fabricated by transfer molding are indispensable for parallel interconnection in high speed, high capacity optical communication systems. This paper proposes a design technique considering the thermal behavior of materials, such as shrinkage and expansion during the molding process, to satisfy geometrical requirements that have less than 1
tolerance. We also designed molds considering the thermal effects of the materials and fabricated multi-channel optical fiber connectors that have less than 1
A Fully Integrated Thin-Film Inductor and Its Application to a DC-DC Converter
Park, Il-Yong ; Kim, Sang-Gi ; Koo, Jin-Gun ; Roh, Tae-Moon ; Lee, Dae-Woo ; Yang, Yil-Suk ; Kim, Jung-Dae ;
ETRI Journal, volume 25, issue 4, 2003, Pages 270~270
This paper presents a simple process to integrate thin-film inductors with a bottom NiFe magnetic core. NiFe thin films with a thickness of 2 to 3
were deposited by sputtering. A polyimide buffer layer and shadow mask were used to relax the stress of the NiFe films. The fabricated double spiral thin-film inductor showed an inductance of 0.49
and a Q factor of 4.8 at 8 MHz. The DC-DC converter with the monolithically integrated thin-film inductor showed comparable performances to those with sandwiched magnetic layers. We simplified the integration process by eliminating the planarization process for the top magnetic core. The efficiency of the DC-DC converter with the monolithic thin-film inductor was 72% when the input voltage and output voltage were 3.5 V and 6 V, respectively, at an operating frequency of 8 MHz.