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ETRI journal 8건

  1. [국내논문]   An Improved Base Station Modulator Design for a CDMA Mobile System  

    Kim, Jin-Up (ETRI ) , Uh, Yoon (Mobile Communications Technology Division, ETRI ) , Kweon, Hye-Yeoun (ETRI)
    ETRI journal v.18 no.4 ,pp. 215 - 227 , 1997 , 1225-6463 ,

    초록

    We propose a new method to eliminate completely the redundant elements in a CDMA (code division multiple access) mobile system. First, we define multilevel logic operation (MLO), which is a new concept to deal with the multilevel logic signals. We prove that the conventional binary logic concept is a subset of the MLO concept. The multilevel logic signal can be directly controlled by using this MLO in place of the binary operation. We applied the MLO to the CDMA base station modulator (BSM) in order to reduce the hardware complexity. In the case of a 3-sectorized cell, this method helps reduce the complexity down the level of below 1% of the conventional CDMA BSM for spreading and filtering, and to 50% for Walsh covering.

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  2. [국내논문]   ATM Interface Technologies for an ATM Switching System  

    Park, Hong-Shik (ATM Access Section, ETRI ) , Kwon, Yool (ETRI ) , Kim, Young-Sup (ATM Access Section, ETRI ) , Kang, Seok-Youl (ATM Technology Department, ETRI)
    ETRI journal v.18 no.4 ,pp. 229 - 244 , 1997 , 1225-6463 ,

    초록

    Realization of the economical, reliable, and efficient ATM interface block becomes an important key to development of the ATM switching system when we consider new issues raised recently. In this paper, we summarize requirements for the ATM interface block and present the UNI (User Network Interface)/NNI (Network Node Interface) architecture to meet these requirements. We also evaluate the performance of the multiplexer adopting the various multiplexing schemes and service disciplines. For ATM UNI/NNI interface technologies, we have developed a new policing device using the priority encoding scheme. It can reduce the decision time for policing significantly. We have also designed a new spacer that can space out the clumped cell stream almost perfectly. This algorithm guarantees more than 99 % conformance to the negotiated peak cell rate. Finally, we propose the interface architecture for accommodation of the ABR (Available Bit Rate) transfer capability. The proposed structure that performs virtual source and virtual destination functions as well as a switch algorithm can efficiently accommodate the ABR service.

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    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  3. [국내논문]   A Methodology for Variable Structure System Specification: Formalism, Framework, and Its Application to ATM-Based Network System  

    Lee, Kyou-H. (Telecommunication Systems and Computer Divisions, ETRI ) , Choi, Kil-Y. (Telecommunication Systems Division, ETRI ) , Kim, Jae-G. (Broadband communication Department, Telecommunication Systems Division, ETRI ) , Vansteenkiste, G.C. (University of Gent)
    ETRI journal v.18 no.4 ,pp. 245 - 264 , 1997 , 1225-6463 ,

    초록

    This paper presents a formalism-based methodology and its implemented environment which constitutes a sound framework for real-time systems development. The software and/or hardware systems developed in such a formal manner are well structured and maintainable. We first propose a set-theoretic VSSS (Variable Structure System Specification) formalism. This formalism is the core of the presented methodology which supports a means of formal specification for real-time systems. We then develop the environment, including VSSS language definition, a translator for the language, and supporting libraries for real-time execution. Finally, a demonstration of the methodology in development of a real-time event manager, a subsystem of an ATM-based communication system, shows the correctness and efficiency of the methodology.

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    회원님의 원문열람 권한에 따라 열람이 불가능 할 수 있으며 권한이 없는 경우 해당 사이트의 정책에 따라 회원가입 및 유료구매가 필요할 수 있습니다.이동하는 사이트에서의 모든 정보이용은 NDSL과 무관합니다.

    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  4. [국내논문]   A New Integrated Software Development Environment Based on SDL, MSC, and CHILL for Large-scale Switching Systems  

    Lee, Dong-Gill (ETRI ) , Lee, Joon-Kyung (ETRI ) , Choi, Wan (Computer Science from Korea Advanced Institute of Science and Technology ) , Lee, Byung-Sun (Korea Advanced Institute of Science and Technology, Software Environments Section, ETRI ) , Han, Chi-Moon (Systems Technology Department, Switching Technologies Division, ETRI)
    ETRI journal v.18 no.4 ,pp. 265 - 286 , 1997 , 1225-6463 ,

    초록

    This paper presents a new software development environment that supports an integrated methodology for covering all phases of software development and gives integrated methods with tools for ITUT (Telecommunication Standardization Section of the International Telecommunication Union) languages. The design of the environment to improve software productivity and quality is based on five main concepts: 1) formal specifications based on SDL (Specification and Description Language) and MSC (Message Sequence Charts) in the design phase, 2) verification and validation of those designs by tools, 3) automatic code generation and a safe separate compilation scheme based on CHILL (CCITT High-Level Language) to facilitate programming-in-the-many and programming-in-the-large. 4) debugging of distributed real-time concurrent CHILL programs, and 5) simulation of application software for integrated testing on the host machine based on CHILL. The application results of the environment compared with other approaches show that the productivity is increased by 19 % because of decreasing implementation and testing cost, and the quality is increased by 83 % because of the formal specifications with its static and dynamic checking facilities.

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    회원님의 원문열람 권한에 따라 열람이 불가능 할 수 있으며 권한이 없는 경우 해당 사이트의 정책에 따라 회원가입 및 유료구매가 필요할 수 있습니다.이동하는 사이트에서의 모든 정보이용은 NDSL과 무관합니다.

    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  5. [국내논문]   Integrated-Optic Polarization Controlling Devices Using Electro-Optic Polymers  

    Oh, Min-Cheol (Research Department, ETRI ) , Hwang, Wol-Yon (Research Department, ETRI ) , Kim, Jang-Joo (Organic Materials for Electronics and Photonics Team, ETRI)
    ETRI journal v.18 no.4 ,pp. 287 - 299 , 1997 , 1225-6463 ,

    초록

    Integrated-optic polarization controlling devices such as polarizers, polarization splitters, and polarization converters, are proposed and demonstrated in nonlinear optic polymers. Poling-induced birefringence in electro-optic polymers is exploited to fabricate the devices. The polymeric waveguide polarizers show low excess losses, and extinction ratios of 20.7 dB and 17.1 dB for TM-pass and TE-pass polarizers, respectively. The polymeric waveguide polarization splitters exhibit TE-TM mode splittings with crosstalk of 14.2 dB and 10.1 dB for TM and TE mode splittings, respectively. The polymeric waveguide polarization converters show successful TE/TM polarization mode conversion with conversion efficiencies of higher than 30 dB. The device employs poling-induced waveguides which have slowly rotating azimuth angle of optic axis along the light propagation direction. The novel polarization converter is insensitive to wavelength and easier to fabricate than the other polarization converters containing periodic structures.

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    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  6. [국내논문]   Importance of Backscattering Effects in Ballistic Quantum Transport in Mesoscopic Ring Structures  

    Shin, Min-Cheol (Research Department in ETRI ) , Park, Kyoung-Wan (Research Department in ETRI ) , Lee, Seong-Jae (Research Department in Electronics and Telecommunications Research Institute ) , Lee, El-Hang (Research Department at ETRI)
    ETRI journal v.18 no.4 ,pp. 301 - 313 , 1997 , 1225-6463 ,

    초록

    We have found that in the ballistic electron transport in a ring structure, the junction-backscattering contribution is critical for all the major features of the Aharonov-Bohm-type interference patterns. In particular, by considering the backscattering effect, we present new and clear interpretation about the physical origin of the secondary minima in the electrostatic Aharonov-Bohm effect and that of the h/2e oscillations when both the electric and magnetic potentials are present. We have devised a convenient scheme of expanding the conductance by the junction backscattering amplitude, which enables us to determine most important electron paths among infinitely many paths and to gain insight about their contributions to the interference patterns. Based on the scheme, we have identified various interesting interference phenomena in the ballistic ring structure and found that the backscattering effect plays a critical role in all of them.

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    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  7. [국내논문]   An Improved Theoretical Model to Explain Electronic and Optical Properties of p-Type GaAs/AlGaAs Superlattices for Multi-Wavelength Normal Incidence Photodetectors  

    Kim, Byoung-Whi (ETRI ) , Choi, Eun-Chang (ATM Switching Section, ETRI ) , Park, Kwon-Chul (ATM Switching Section, ETRI ) , Kang, Seok-Youl (Software Development Section, ETRI)
    ETRI journal v.18 no.4 ,pp. 315 - 338 , 1997 , 1225-6463 ,

    초록

    We extend our previous theoretical analysis of electronic and optical properties of p-type quantum well structures based on the two heavy- and light-hole system to include all the three valence bands. These theories are then used to clarify the origin of the normal incidence absorption and photo current at photon wavelengths of 2 - 3 ${\mu}m$ , which was observed in addition to the absorption around 8 ${\mu}m$ by a recent experimental investigation with heavily doped p-type GaAs/AlGaAs multi-quantum well (MQW) structures. In the theoretical analysis, the Hartree and exchange-correlation many-body interactions are taken into account within one-particle local density approximation, and it is shown that normal incidence absorption occurs in two wavelength regions over the transition energy range higher than barrier height for p-type GaAs/AlGaAs superlattices with well doping of $2{\times}10^{19}\;cm^{-3}$ ; one region has broad absorption peaks with coefficients of about 5000 $cm^{-1}$ around 8 ${\mu}m$ , and the other has two rather sharp peaks at 2.7 ${\mu}m$ and 3.4 ${\mu}m$ with 1800 $cm^{-1}$ and 1300 $cm^{-1}$ , respectively. The result indicates that the theory explains the experimental observation well, as the theoretical and experimental results are in close agreement in general absorption features.

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    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  8. [국내논문]   Nucleation and Growth of b-Axis Oriented $PrBa_2Cu_3O_{7-x}$ Thin Films on $LaSrGaO_4$ (100) Substrates  

    Sung, Gun-Yong (Research Department, ETRI ) , Suh, Jeong-Dae (Research Department of ETRI)
    ETRI journal v.18 no.4 ,pp. 339 - 346 , 1997 , 1225-6463 ,

    초록

    Good quality a-axis oriented thin films of $YBa_2Cu_3O_{7-x}$ may be grown by the use of a $PrBa_2Cu_3O_{7-x}$ (PBCO) layer as a template. Here we present a detailed study of the nucleation of the PBCO layer, explaining the orientations observed. It is determined that the wavy surface of a $LaSrGaO_4$ (LSGO) (100) substrate consists of the {101} planes by observing cross-sectional transmission electron microscopy images of the interface between the PBCO film and the substrate. The images and selected area diffraction patterns show that a mixed c-and b-axis oriented PBCO layer was initially grown on the substrate, followed by pure b-axis oriented PBCO growth. We explain that the c-axis oriented growth is the result of the growth of the PBCO (019) planes on the LSGO (101) planes. We conclude that the nucleation and growth of the PBCO films at the initial stages depends on the crystallographic plane of the substrate surfaces, however, as the film grows further, the kinetics of the deposition process favors b-axis oriented growth.

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