• The Transactions of the Korea Information Processing Society
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• v.4 no.8
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• pp.2106-2119
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• 1997

NDAS(Network Data Access System) is a system that interconnects high speed network(B-ISDN) and Local Area Network(Ethernet, FDDI). Nowadays, the request of multimedia data increases rapidly, so NDAS system must accept and process that request efficiently. Comparing with normal data traffic characteristics, multimedia data traffic characteristics are much complex, so it is necessary to implement the system that can cover such factor. In this paper, we suggest a NDAS hardware system model and also we propose a proper buffer size of NDAS system through the simulation. For measuring the proper buffer size of NDAS, we assumed two different simulation models, one is the case of using only one buffer and the other is the case of using two different buffers for Ethernet and FDDI, respectively. After comparing and analyzing simulation results, we suggest the proper NDAS system buffer size.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3249-3252
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• 1999

In this paper, we present the Tele-PACS of radiology, which uses the communication network as asymetric satellite data communication system. The asymetric satellite data communication system uses receive-only satellite links for data delivery and PSTN(Public Switched Telephone Network) modem or N-ISDN(Integrate Services Digital Network) for communication. The satellite communication linking shows the very high-speed performance than terrestial linking such as 28.8 kbps modem linking and 56Kbps linking. The satellite linking is 5 - 10 times faster than the 56Kbps linking. We conclude that 1) Satellite networking is currently the cheapest and fastest solution for internet access. 2) Web-based Image-Viewer enables small size hospitals in rural area to connect to central PACS easily and to retrieve the image data reliably. 3) The suggested teleradiology system using satellite networking could be adequate to fast telemedicine and telecare for rural hospitals especially located in geographically isolated areas such as islands.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.114-117
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• 1996

In this study, remote articulation training system which connects the hearing disabled trainee and the speech therapist via B-ISDN is introduced. The hearing disabled does not have the hearing feedback of his own pronunciation, and the chance of watching his speech organs' movement trajectory will offer him the self-training of articulation. So the system has two purposes of self articulation training and trainer's on-line checking in remote place. We estimate the vocal tract articulatory movements from the speech signal using inverse modelling and display the movement trajectory on the sideview of human face graphically. The trajectories of trainees' articulation is displayed along with the reference trajectories, so the trainee can control his articulating to make the two trajectories overlapped. For on-line communication and ckecking training record, the system has the function of video conferencing and transferring articulatory data.

• IE interfaces
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• v.11 no.2
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• pp.39-48
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• 1998

It is strongly believed that Video on Demand(VOD) will become one of the most promising services for Broadband Integrated Services Digital Network(B-ISDN). VOD service can be classified into two types of services: Near VOD(NVOD) and Interactive VOD(IVOD). Although VOD network requires many kinds of resources, we only consider video servers, programs. and storages. In the network. some video servers should be installed at some nodes(especially, at the root node for NVOD service). so that each node with video server stores video programs and distributes stored programs to customers. We take into account three kinds of costs related with the above resources: a program transmission cost, a program storage cost, and a video server installation cost. There exists a trade-off relationship among those three costs according to the locations of video servers and the kinds of programs stored at each video server. Given a multi-level VOD network and the total number of programs being served in the network. the resource. optimization problem for providing both IVOD and NVOD services is to determine where to install video servers, and which and how many programs should be stored at each video server, in order to minimize the total cost. In this paper we develop an efficient dynamic programming algorithm to solve the problem. We also implement the algorithm based on two different service policies assumed in this paper.

• The Transactions of the Korea Information Processing Society
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• v.6 no.2
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• pp.459-466
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• 1999

I broadband ISDN every packet will show different result if it would be processed according to its usage by the server. That is, normal data won't show big differences if they would be processed at normal speed. But it will improve the quality of service to process some kinds of data - for example real time video or voice type data or some data for a bid to by something through the internet - more fast than the normal type data. solution for this problem was suggested - priority packets. But the analyses of them are under way. Son in this paper a switching system for an output queuing model in a single server was assumed and some packets were given priorities and analysed. And correlation, simulating real life situation, was given too. These packets were analysed through three cases, first packets having no correlation, second packets having only correlation and finally packets having priority three cases, first packets having no correlation, second packets having only correlation and finally packets having priority and correlation. The result showed that correlation doesn't affect the mean delay time and the high priority packets have improved mean delay time regardless of the arrival rate. Those packets were assumed to be fixed-sized like ATM fixed-sized cell and the contention strategy was assumed to be short bus contention method for the output queue, and the mean delay length and the maximum 버퍼 length not to lose any packets were analysed.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.515-517
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• 2003

In this paper we examine the effects of the required portions of guard timing spaces in a MAC frame of ETSI BRAN HIPERLAN/2 system such as inter-mobile guard timing space in UL(Up Link) duration, inter-RCH(Random CHannel) guard timing space, sector switch guard timing space. In particular, we calculate the number of OFDM(Orthogonal Frequency Division Multiplexing) symbols required for these guard timing spaces in a MAC frame. We them evaluate the throughput of HIPERLAN/2 system as we vary parameter such as the guard time values defined in [2], the number of DLCCs(Data Link Control Connections), and the number of RCHs. Finally we show by numerical results that the portions for the 새심 summation of required guard timing spaces in a MAC frame are not negligible, and that they should be properly considered when trying to evaluate the performance of MAC protocol of HIPERLAN/2 system and also when determining the number of RCHs as well as the number of DLCCs in UL PDU trains at an AP/CC(Access Point/Central Controller).

• Journal of Korea Multimedia Society
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• v.4 no.5
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• pp.455-464
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• 2001

For future multimedia services, one of the most crucial issues is building an access network that can accommodate multimedia services in subscriber network. The VB5.2 interface of B-ISDN located between an access network and a service node allows dynamic allocation and release of ATM resources. The SG 13 of ITU-T is standardizing the B-BCC protocol, which is sequentially interworked with signaling protocols in the service node. To minimize a connection setup delay of the sequential interworking mode, we proposed the parallel interworking model in which the SN executes simultaneously the connection control protocol of VB5.2 interface and signaling protocol. We simulate two interworking models in terms of a connection setup delay and a completion ratio. The results of simulation show that our proposed parallel interworking model for the VB5.2 interface reduces the setup delay and has the similar completion ratio compared to the sequential interworking model. however, the connection setup delay of parallel interworking model becomes about seven tenths of that of the sequential interworking model and the improvement become larger as the arrival rate increased.

• The Transactions of the Korea Information Processing Society
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• v.4 no.6
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• pp.1589-1600
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• 1997

The construction of optical access network costs upper 40% in total installation cost of total optical network. Optimization of access network therefore is core in optical network. Advanced countries include EU, Japan and USA already have researched access network. This paper presents analysis of three broad-band fiber-optics subscriber loop architectures(HFC, ATM-PON, Super PON). The analyses focus on the specific demonstrated architectures and use component cost projections to estimate future network costs on a per-subscriber basis. We use TITAN(Tool for Introduction Scenarios and Techno-Economic Evaluation of The Access Network) model. We find that ATM-PON can deliver voice and ISDN data at installed first costs than the other architectures. This is due to the sharing bandwidth among a cluster of subscribers within Curb. This work intends to support establishing guidelines for strategic decisions regarding the development of the access network alternatives of different operators.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9B
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• pp.822-831
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• 2008

This paper examines the theoretical and empirical technology diffusion processes to understand the Korean success in the internet access service markets. In order to do this, first, we propose an integrated demand diffusion model in terms of competition of inter-and intra-technologies and market structure as represented by the number of operators in the market. Second, by using the proposed model, we analyze the dynamic diffusion processes of Korean internet access services such as Narrow-band technology including Dial modem vs. Broad-band technology including ISDN, xDSL and Cable modem. The competition of inter-and intra-technologies as well as the extent of market competition has made a positive effect on the diffusion patterns of internet access demand. And also we propose, based on the proposed model and its empirical results, several implications for diffusion strategies and policies in the future of ICT market in Korea.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2348-2356
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• 1997

This paper describes a method of AAL(SSCOP) protocol conformance testing and its result analysis in ATM network. Terminal equipment(TE) that implements protocols for connecting ATM network shall be verified if appropriately implement by conformance testing. The protocol specifications and the testing methodology are recommended or standardized by international standardization organization(ITU-T, ISO, etc.). The ATM AAL (SSCOP) protocol which selected for describing conformance test procedure is standardized in ITU-T Q.2110 and ATM Forum UNI 3.1 which are same in contents. Also Testing standard like ATS for SSCOP is specified in ATM Forum 95-1459R2. Construction of conformance testing environment is necessary to coordinate in relations with standards, then testing must beexecuted at that environment and the results from the test system analyzed. For this, it is necessary to select any test case from standard for testing and to make ETS. The ETS is proted on the test system and conformance testing will execute on that system. Finally the result from the test system is to analyze. This conformance testing procedure is applicable to the same other test cases in SSCOP and protocols in any communcation networks.