• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.63-72
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• 2011

Broadcast-based data dissemination has become a widely accepted approach of communication in the mobile computing environment. However, with a large set of data items, the expected delay of receiving a desired data increases due to the sequential nature of the broadcast channel. With the objective of minimizing this wait time, this paper explores the problem of data broadcast over multiple channels. In traditional approaches, data items are partitioned based on their access probabilities and allocated on multiple channels, assuming flat data scheduling per channel. If the data items allocated on the same channel are broadcast in different frequencies based on their access probabilities, the performance will be enhanced further. In this respect, this paper proposes a new broadcast scheduling scheme named two level dynamic programming(TLDP) which can reflect a variation of access probabilities among data items allocated on the same channel.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.3887-3907
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• 2015

This paper introduces a full duplex single secondary user multiple-input multiple-output (FD-SSU-MIMO) cognitive radio network, where secondary user (SU) opportunistically accesses the authorized spectrum unoccupied by primary user (PU) and transmits data based on FD-MIMO mode. Then we study the network achievable average sum-rate maximization problem under sum transmit power budget constraint at SU communication nodes. In order to solve the trade-off problem between SU's sensing time and data transmission time based on opportunistic spectrum access (OSA) and the power allocation problem based on FD-MIMO transmit mode, we propose a simple trisection algorithm to obtain the optimal sensing time and apply an alternating optimization (AO) algorithm to tackle the FD-MIMO based network achievable sum-rate maximization problem. Simulation results show that our proposed sensing time optimization and AO-based optimal power allocation strategies obtain a higher achievable average sum-rate than sequential convex approximations for matrix-variable programming (SCAMP)-based power allocation for the FD transmission mode, as well as equal power allocation for the half duplex (HD) transmission mode.

• Journal of the Korean Society for information Management
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• v.24 no.2
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• pp.89-104
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• 2007

This research attempts to give a personalized recommendation framework in large-sized music contents environment. Despite of existing studios and commercial contents for recommendation systems, large online shopping malls are still looking for a recommendation system that can serve personalized recommendation and handle large data in real-time. This research utilizes data mining technologies and new pattern matching algorithm. A clustering technique is used to get dynamic user segmentations using user preference to contents categories. Then a sequential pattern mining technique is used to extract contents access patterns in the user segmentations. And the recommendation is given by our recommendation algorithm using user contents preference history and contents access patterns of the segment. In the framework, preprocessing and data transformation and transition are implemented on DBMS. The proposed system is implemented to show that the framework is feasible. In the experiment using real-world large data, personalized recommendation is given in almost real-time and shows acceptable correctness.

• Journal of Korea Society of Industrial Information Systems
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• v.5 no.2
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• pp.22-31
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• 2000

The VB5.2 interface of B-lSDN, that is located between an access network and a service node, allows dynamic allocation and release of ATM resources. In this paper, we propose the B-ANCC protocol of the VB5.2 interface to minimize the overall connection setup delay by introducing the access network. The B-ANCC protocol enhances the B-BCC protocol and adopts a parallel interworking function with signaling protocols in the service node. To confirm the correctness of the proposed B-ANCC protocol, we validate it using the automated validation tool, SPIN. We analyze and simulate the sequential interworking model based on the B-BCC protocol and the parallel interworking model based on the B-ANCC protocol, in terms of a connection setup delay and a completion ratio. It is shown that our proposed parallel interworking model with B-ANCC reduces a setup delay and improves a completion ratio compared to the sequential interworking model with B-BCC.

• Journal of the Korea Society of Computer and Information
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• v.20 no.1
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• pp.185-195
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• 2015

During hospital peak times of outpatients, an effective mechanism that informs the newly receipted patient information to corresponding medical departments is lacking in current hospital reception systems. Since every department repeatedly searches entire patient reception database in sequential manner to acquire its reception information, this is a significant performance degradation factor in hospital information system. To improve hospital reception system efficiency, we developed two web socket based systems, a primary key transmitting batch system and a reception information transmitting real time system. The former reduced database access time compared to sequential search system as well as kept search time low regardless of receipted patient number. The latter effectively reduced waiting list updating time in request/response patient reception system by eliminating database access.

• Journal of KIISE:Information Networking
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• v.27 no.2
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• pp.237-246
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• 2000

A broadband access network in B-ISDN subscriber network, plays a role of concentration or multiplexing of various subscribers into a service node. For call and connection control functions, DSS2 and B-ISUP signalling protocols are standardized for each of a subscriber side and a network node. B-BCC and B-ANCC protocol were proposed for VB5.2 interface. This interface allows dynamic control of ATM connections at the broadband access network. To establish an end-to-end ATM connection, interworking functions between VB5.2 interface's connection control protocol and the signalling protocol, are performed at the service node. A sequential interworking model and a parallel interworking model were proposed for these interworking functions. The sequential interworking model recommended by ITU-T causes an overall connection setup delay by introducing the access network, because this model proceeds the signalling protocol of network node after the response of VB5.2 interface protocol. On the other hand, the parallel interworking model proceeds the signalling protocol and the VB5.2 interface protocol simultaneously. The simultaneity of the parallel interworking model minimizes the overall connection setup delay. In this paper, we analyze and simulate above two interworking models with B-BCC or B-ANCC protocol in terms of a connection setup delay and completion ratio.

• Journal of Digital Convergence
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• v.17 no.12
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• pp.23-34
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• 2019

The purpose of this study was to examine the relationship between the access level of digital information service and life satisfaction level of the middle and high-aged people and to analyze the Sequential Mediation Effects on online social engagement and online network activities. To this end, we analyzed the effects of multiple mediations on 1,491 seniors who responded to the 2018 digital information gap survey. The results of the study are as follows: First, this study confirmed that there is a statistically significant relationship between the access levels of digital information service and the life satisfaction. Second, the results showed that impact of digital information access level on life satisfaction among high-aged people was higher when they were engaged in both online social activities and online networking, rather than only involved in online social activities. Overall, this study comprehensively examined the relationship among the level of digital information access, life satisfaction, online social engagement, and online networking, which is meaningful in that it can be used as data for reconsideration of the digital information services and life satisfaction of the high-aged people.

• Journal of KIISE:Software and Applications
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• v.26 no.10
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• pp.1178-1178
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• 1999

A spatial join has the property that its execution time exponentially increases in proportion to the number of spatial objects. Recently, there have been many attempts for improving the performance of the spatial join by using parallel processing schemes, In the case of executing parallel spatial join using the parallel machine with shared disk architecture, the disk bottleneck of parallel processing of spatial join worsens in comparison with sequential spatial join. This paper presents the algorithms of task creation and assignment to reduce the disk bottleneck caused by accessing the shared disk at the same time, and to minimize message passing between processors, This paper proposes object caching which is a higher level of abstraction than page caching, and uses it to do creation and assignment of tasks according to temporal and spatial localities for minimizing disk access time. The object caching shows the performance improvement of 50%. The task creation and assignment using localities gives the gain of 30% and 20%. Overall performance evaluation of the proposed algorithms shows 7.2 times speed up than those of sequential execution of spatial joins.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.2
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• pp.233-237
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• 2010

The recent advance of sensor networks and ubiquitous techniques allow collecting and analyzing of the data which overcome the limitation imposed by time and space in real-time for making decisions. Also, analysis and prediction of collected data can support useful and necessary information to users. The collected data in sensor networks environment is the stream data which has continuous, unlimited and sequential properties. Because of the continuous, unlimited and large volume properties of stream data, managing stream data is difficult. And the stream data needs dynamic processing method because of the memory constraint and access limitation. Accordingly, we analyze correlation stream data using principal component analysis. And using result of analysis, it helps users for making decisions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10C
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• pp.992-998
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• 2005

In this paper, An Ultra Fast Acquisition Algorithm of low transmission rate ultra-wideband(UWB) systems for car positioning and traffic light controling is proposed. Since the acquisition algorithms for CDMA system are not fast enough to access the low transmission rate UWB systems, the new ultra fast acquisition scheme which can be implemented with low cost and simplified circuit is required. The proposed algorithm adopted the Recurrent Sequential Estimation scheme and trinomial M-sequence. Therefore, The proposed scheme can reduce the average acquisition time in $1\~3{\mu}sec$ with simple circuit, even for the UWB systems which use long pseudo-noise(PN) sequence and transmit low power below the FCC EIRP emission limits. The simulation results for the average acquisition time of the proposed scheme are compared with the ones of the existing acquisition schemes.