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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
Electronics and Telecommunications Research Institute
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Volume & Issues
Volume 24, Issue 6 - Dec 2002
Volume 24, Issue 5 - Oct 2002
Volume 24, Issue 4 - Aug 2002
Volume 24, Issue 3 - Jun 2002
Volume 24, Issue 2 - Apr 2002
Volume 24, Issue 1 - Feb 2002
Selecting the target year
Polymer-Based Devices for Optical Communications
Lee, Myung-Hyun ; Ju, Jung-Jin ; Park, Sun-Tak ; Do, Jung-Yun ; Park, Seung-Koo ;
ETRI Journal, volume 24, issue 4, 2002, Pages 259~259
Polymers are emerging as new alternative materials for optical communication devices. We developed two types of polymer-based devices for optical communications. One type is for ultra high-speed signal processing that uses nonlinear optical (NLO) polymers in such devices as electro-optic (EO) Mach-Z
hnder (MZ) modulators and EO 2
2 switches. The other is for WDM optical communications that use low-loss optical polymers in such devices as 1
2, 4-arrayed 2
2 digital optical switches (DOSs) and 16
16 arrayed waveguide grating (AWG) routers. For these devices, we synthesized a polyetherimide-disperse red 1 (PEI-DR1) side chain NLO polymer and a low-loss optical polymer known as fluorinated polyaryleneethers (FPAE). This paper presents the details of our development of these polymeric photonic devices considering all aspects from materials to packaging.
Self-Consistent Subband Calculations of AlGaN/GaN Single Heterojunctions
Lee, Kyu-Seok ; Yoon, Doo-Hyeb ; Bae, Sung-Bum ; Park, Mi-Ran ; Kim, Gil-Ho ;
ETRI Journal, volume 24, issue 4, 2002, Pages 270~270
We present a self-consistent numerical method for calculating the conduction-band profile and subband structure of AlGaN/GaN single heterojunctions. The subband calculations take into account the piezoelectric and spontaneous polarization effect and the Hartree and exchange-correlation interaction. We calculate the dependence of electron sheet concentration and subband energies on various structural parameters, such as the width and Al mole fraction of AlGaN, the density of donor impurities in AlGaN, and the density of acceptor impurities in GaN, as well as the electron temperature. The electron sheet concentration was sensitively dependent on the Al mole fraction and width of the AlGaN layer and the doping density of donor impurities in the AlGaN. The calculated results of electron sheet concentration as a function of the Al mole fraction are in excellent agreement with some experimental data available in the literature.
Bit Allocation for Interframe Video Coding Systems
Kim, Wook-Joong ; Kim, Seong-Dae ; Kim, Jin-Woong ;
ETRI Journal, volume 24, issue 4, 2002, Pages 280~280
In this work, we present a novel approach to the bit allocation problem that aims to minimize overall distortion subject to a bit rate constraint. The optimal solution can be found by the Lagrangian method with dynamic programming. However, the optimal bit allocation for block-based interframe coding is practically unattainable because of the interframe dependency of macroblocks caused by motion compensation. To reduce the computational burden while maintaining a result close to the optimum, i.e., near optimum, we propose an alternative method. First, we present a partitioned form of the bit allocation problem: a "frame-level problem" and "one-frame macroblock-level problems." We show that the solution to this new form is also the solution to the conventional bit allocation problem. Further, we propose a bit allocation algorithm using a "two-phase optimization technique" with an interframe dependency model and a rate-distortion model.
Active-Matrix Field Emission Display with Amorphous Silicon Thin-Film Transistors and Mo-Tip Field Emitter Arrays
Song, Yoon-Ho ; Hwang, Chi-Sun ; Cho, Young-Rae ; Kim, Bong-Chul ; Ahn, Seong-Deok ; Chung, Choong-Heui ; Kim, Do-Hyung ; Uhm, Hyun-Seok ; Lee, Jin-Ho ; Cho, Kyoung-Ik ;
ETRI Journal, volume 24, issue 4, 2002, Pages 290~290
We present, for the first time, a prototype active-matrix field emission display (AMFED) in which an amorphous silicon thin-film transistor (a-Si TFT) and a molybdenum-tip field emitter array (Mo-tip FEA) were monolithically integrated on a glass substrate for a novel active-matrix cathode (AMC) plate. The fabricated AMFED showed good display images with a low-voltage scan and data signals irrespective of a high voltage for field emissions. We introduced a light shield layer of metal into our AMC to reduce the photo leakage and back channel currents of the a-Si TFT. We designed the light shield to act as a focusing grid to focus emitted electron beams from the AMC onto the corresponding anode pixel. The thin film depositions in the a-Si TFTs were performed at a high temperature of above 360°C to guarantee the vacuum packaging of the AMC and anode plates. We also developed a novel wet etching process for
a-Si etching with high etch selectivity to intrinsic a-Si and used it in the fabrication of an inverted stagger TFT with a very thin active layer. The developed a-Si TFTs performed well enough to be used as control devices for AMCs. The gate bias of the a-Si TFTs well controlled the field emission currents of the AMC plates. The AMFED with these AMC plates showed low-voltage matrix addressing, good stability and reliability of field emission, and good light emissions from the anode plate with phosphors.
An ATM Network Management System for Point-to-Multipoint Reservation Service
Hong, Daniel Won-Kyu ; Hong, Choong-Seon ; Yun, Dong-Sik ; Yoo, Jae-Hyoung ; Kim, Woo-Sung ;
ETRI Journal, volume 24, issue 4, 2002, Pages 299~299
This paper describes an integrated network management framework for providing point-to-multipoint reservation service (PMRS) in an ATM network. There are two major issues confronting the network service provider in relation to this service: one is to rapidly confirm the acceptability of the subscriber's reservation at subscription time, and the other is to punctually activate the reserved point-to-multipoint service. To meet these requirements, we developed a service provision model (SPM) and a network resource model of a bandwidth allocation timetable (BATT). We propose a point-to-multipoint routing algorithm composed of ordering and backtracking procedures, which can find the best branch point under the complex network topology and can add more destinations to the existing point-to-multipoint route. We demonstrate the feasibility of the SPM, the BATT, and the point-to-multipoint routing algorithm by implementing our schemes and analyzing their performance under the operational ATM network of KT(Korea Telecom).
A Data Burst Assembly Algorithm in Optical Burst Switching Networks
Oh, Se-Yoon ; Hong, Hyun-Ha ; Kang, Min-Ho ;
ETRI Journal, volume 24, issue 4, 2002, Pages 311~311
Presently, optical burst switching (OBS) technology is under study as a promising solution for the backbone of the optical Internet in the near future because OBS eliminates the optical buffer problem at the switching node with the help of no optical/electro/optical conversion and guarantees class of service without any buffering. To implement the OBS network, there are a lot of challenging issues to be solved. The edge router, burst offset time management, and burst assembly mechanism are critical issues. In addition, the core router needs data burst and control header packet scheduling, a protection and restoration mechanism, and a contention resolution scheme. In this paper, we focus on the burst assembly mechanism. We present a novel data burst generation algorithm that uses hysteresis characteristics in the queueing model for the ingress edge node in optical burst switching networks. Simulation with Poisson and self-similar traffic models shows that this algorithm adaptively changes the data burst size according to the offered load and offers high average data burst utilization with a lower timer operation. It also reduces the possibility of a continuous blocking problem in the bandwidth reservation request, limits the maximum queueing delay, and minimizes the required burst size by lifting up data burst utilization for bursty input IP traffic.
Estimating the Position of Mobiles by Multi-Criteria Decision Making
Lee, Jong-Chan ; Ryu, Byung-Han ; Ahn, Jee-Hwan ;
ETRI Journal, volume 24, issue 4, 2002, Pages 323~323
In this study, we propose a novel mobile tracking method based on Multi-Criteria Decision Making (MCDM), in which uncertain parameters-the received signal strength, the distance between the mobile and the base station, the moving direction, and the previous location-are used in the decision process using the aggregation function in the fuzzy set theory. Through numerical results, we show that our proposed mobile tracking method provides a better performance than the conventional method using the received signal strength.
Breakdown Voltage Improvement of p-LDMOSFET with an Uneven Racetrack Source for PDP Driver IC Applications
Roh, Tae-Moon ; Lee, Dae-Woo ; Yang, Yil-Suk ; Koo, Jin-Gun ; Kim, Jong-Dae ;
ETRI Journal, volume 24, issue 4, 2002, Pages 328~328
We investigated the electrical characteristics of p-channel double-diffused MOSFETs (p-LDMOSFETs) with an uneven racetrack source (URS) and a conventional racetrack source (CRS) for PDP driver IC applications. The breakdown voltage of the p-LDMOSFET with the URS in offstate was nearly the same as the p-LDMOSFET with the CRS. However, the breakdown voltage of the p-LDMOSFET with the URS in on-state was about 30% higher than that of the p-LDMOSFET with the CRS, while the saturated drain current of the p-LDMOSFET with the URS was only about 4% lower than that of the p-LDMOSFET with the CRS.