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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 20, Issue 4 - Dec 1998
Volume 20, Issue 3 - Sep 1998
Volume 20, Issue 2 - Jun 1998
Volume 20, Issue 1 - Mar 1998
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An Extended Service Filtering Technique for Mass Calling-Type Services Using Intelligent Peripheral in an SCP-Bound Network
Jeong, Kwang-Jae ; Kim, Tae-Il ; Choi, Go-Bong ;
ETRI Journal, volume 20, issue 2, 1998, Pages 115~115
This paper proposes an extended service filtering technique to prevent overload in service control point (SCP) due to televoting (VOT) or mass calling (MAS) services with the heavy traffic characteristics. Also, this paper compares this extended technique with the existing overload control techniques, and calculates steady state call blocking probabilities in intelligent network (IN) under overload conditions. The proposed technique considers SCP overload and IN Capability Set (CS)-1 services (such as VOT or MAS service) that have to use the specialized resources of intelligent peripheral (IP). This technique uses first an activating step in which SCP requests service filtering to service switching point (SSP). Then, in the filtering step, SSP sends filtering results to SCP periodically or each N-calls. Also, when filtering time-out expires, SSP stops service filtering, and sends service filtering response to SCP in the deactivating step. This paper applies this technique to VOT/MAS service, and calculates SCP and SSP-IP (circuit) call blocking probabilities by using an analytical VOT/MAS service model. With the modeling and analyzing of this new technique, it shows that this technique reduces the traffic flow into SCP from SSP and IP prominently.
A New Blind Beamforming Procedure Based on the Conjugate Gradient Method for CDMA Mobile Communications
Shin, Eung-Soon ; Choi, Seung-Won ; Shim, Dong-Hee ; Kyeong, Mun-Geon ; Chang, Kyung-Hi ; Park, Youn-Ok ; Han, Ki-Chul ; Lee, Chung-Kun ;
ETRI Journal, volume 20, issue 2, 1998, Pages 133~133
The objective of this paper is to present an adaptive algorithm for computing the weight vector which provides a beam pattern having its maximum gain along the direction of the mobile target signal source in the presence of interfering signals within a cell. The conjugate gradient method (CGM) is modified in such a way that the suboptimal weight vector is produced with the computational load of O(16N), which has been found to be small enough for the real-time processing of signals in most land mobile communications with the digital signal processor (DSP) off the shelf, where N denotes the number of antenna elements of the array. The adaptive procedure proposed in this paper is applied to code division multiple access (CDMA) mobile communication system to show its excellent performance in terms of signal to interference plus noise ratio (SINR), bit error rate (BER), and capacity, which are enhanced by about 7 dB,
times, and 7 times, respectively, when the number of antenna elements is 6 and the processing gain is 20 dB.
Specification of Communication Services for Multimedia Cooperative Applications Based on the Reference Model of ODP
Yi, Jong-Hwa ; Pastor, Encarna ;
ETRI Journal, volume 20, issue 2, 1998, Pages 149~149
Between a wide range of distributed applications, this work is particularly focused on those applications which allow a group of persons, who are geographically distributed, to interact and cooperate exchanging different kind of information in order to realize group activities in a common work environment. In this paper we realized a study of this kind of applications to identify general and functional characteristics which will then enable us to determine their communication requirements. Also, we analyzed the existent support architectures to examine whether they support multimedia cooperative applications. Based on the results of analysis, we proposed a set of communication functions needed additionally to support these applications, using the ODP(Open Distributed Processing) modelling concepts, rules and view points as our global design methodology.
Design of ATM Networks with Multiple Traffic Classes
Ryu, Byung-Han ; Cho, Cheol-Hye ; Ahn, Jee-Hwan ;
ETRI Journal, volume 20, issue 2, 1998, Pages 171~171
In this paper, we propose a new heuristic design algorithm for the virtual path (VP)-based ATM network with multiple traffic classes, in which QoS constraints associated with traffic class are taken into account. The minimum bandwidth of VP required to carry given amount of traffic is obtained by utilizing an equivalent bandwidth concept, and the route of each VP is placed so that the network cost is minimized while the QoS requirement is fulfilled To evaluate our design algorithm, we consider two kinds of traffic: voice traffic as low speed service and still picture traffic as high speed service. Through numerical examples, we demonstrate that our design method can achieve an efficient use of network resources, which results in providing a cost-effective VP-based ATM network.
Managing Complexity in Object-Oriented Analysis
Ine, So-Ran ; Youn, Cheong ; Misbah, Uddin Mirza ; Lee, Kwon-Il ; Cha, Seung-Hoon ; Byoun, Bo-Gyun ; Bae, Doo-Hwan ;
ETRI Journal, volume 20, issue 2, 1998, Pages 192~192
The current approaches in Object-Oriented Analysis have limitations on modeling complex real world systems because they require priori knowledge about objects and their interactions before applying them. This may be practical in small systems and systems with clear domain knowledge, but not in large real world systems with unclear domain knowledge. Our approach uses a stepwise refinement technique in a top-down manner to the Object-Oriented Analysis stage with the application of use cases. This approach is especially good for new areas where we do not know all the information in advance. We present the approach with an example of its application to the B-ISDN service modeling and distributed systems.
Nonlinear Noise-Induced Transitions in Active Rotator Model
Kim, Seung-Hwan ; Park, Seon-Hee ; Ryu, Chang-Su ;
ETRI Journal, volume 20, issue 2, 1998, Pages 214~214
We investigate noise-induced transitions in active rotator model with a fluctuating threshold in the presence of an additive noise. The fluctuation of the threshold depends on the additive noise in a nonlinear fashion. In the white-noise limit of the fluctuation, the Fokker-Planck equation of the system reduces to that of the system with correlated linear fluctuation implying that the nonlinearity may be transformed into the correlation of linear noises. We also investigate the system with a nonlinear colored noise which depends on the additive noise as its square. The system shows a single peak, two peaks, and three peaks in its steady state probability distribution according to the noise intensities and the correlation time whose change leads to peak-creating, peak-splitting, and peak-merging transitions.
Realization of Vertically Stacked InGaAs/GaAs Quantum Wires on V-Grooves with (322) Facet Sidewalls by CHEMICAL Beam Epitaxy
Kim, Sung-Bock ; Ro, Jeong-Rae ; Lee, El-Hang ;
ETRI Journal, volume 20, issue 2, 1998, Pages 231~231
We report, for the first time, the fabrication of vertically stacked InGaAs/GaAs quantum wires (QWRs) on V-grooved substrates by chemical beam epitaxy (CBE). To fabricate the vertically stacked QWRs structure, we have grown the GaAs resharpening barrier layers on V-grooves with (100)-(322) facet configuration instead of (100)-(111) base at 450
. Under the conditions of low growth temperature, the growth rate of GaAs on the (322) sidewall is higher than that at the (100) bottom. Transmission electron microscopy verifies that the vertically stacked InGaAs QWRs were formed in sizes of about
. Three distinct photoluminescence peaks related with side-quantum wells (QWLs), top-QWLs and QWRs were observed even at 200 K due to sufficient carrier and optical confinement. These results strongly suggest the existence of the quantized state in the vertically stacked InGaAs/GaAs QWRs grown by CBE.
Characteristics of Ferroelectric Transistors with
Lyu, Jong-Son ; Jeong, Jin-Woo ; Kim, Kwang-Ho ; Kim, Bo-Woo ; Yoo, Hyung-Joun ;
ETRI Journal, volume 20, issue 2, 1998, Pages 241~241
The structure and electrical characteristics of metal-ferroelectric-semiconductor FET(MFSFET) for a single transistor memory are presented. The MFSFET was comprised of polysilicon islands as source/drain electrodes and
film as a gate dielectric. The polysilicon source and drain were built-up prior to the formation of the ferroelectric film to suppress a degradation of the film due to high thermal cycles. From the MFS capacitor, the remnant polarization and coercive field were measured to be about
and 100 kV/cm, respectively. The fabricated MFSFETs also showed good hysteretic I-V curves, while the current levels disperse probably due to film cracking or bad adhesion between the film and the Al electrode.