• The Journal of the Korea Contents Association
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• v.10 no.4
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• pp.84-90
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• 2010

DBMS is used for a range of applications from data warehousing through on-line transaction processing. As a result of this demand, DBMS has continued to grow in terms of its size. This growth invokes the most important issue of manually tuning the performance of DBMS. The DBMS tuning should be adaptive to the type of the workload put upon it. But, identifying workloads in mixed database applications might be quite difficult. Therefore, a method is necessary for identifying workloads in the mixed database environment. In this paper, we propose a SVM workload classifier to automatically identify a DBMS workload. Database workloads are collected in TPC-C and TPC-W benchmark while changing the resource parameters. Parameters for SVM workload classifier, C and kernel parameter, were chosen experimentally. The experiments revealed that the accuracy of the proposed SVM workload classifier is about 9% higher than that of Decision tree, Naive Bayes, Multilayer perceptron and K-NN classifier.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10C
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• pp.981-990
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• 2006

In this paper, we introduce the concept of a subcarrier-based virtual multiple antennas (SV-MIMO) for OFDM cellular systems, where the multiple antenna techniques are performed on a set of subcarriers, not on the actual multiple antennas. The virtual multiple antenna system can support multiple users simultaneously as well as reduce inter-cell interference (ICI) form adjacent cells with a single antenna. Also, this technique is easily extended to multiple antenna environments. The virtual multiple antenna techniques can be divided into a virtual smart antenna technique and a virtual MIMO technique. Especially, this method effectively reduces ICI at cell boundary with frequency reuse factor equal to 1, and can support flexible resource allocation depending on the amount of interference. It is shown by simulation that the proposed method is superior to conventional method under the same condition of data transmission.

• Journal of Internet Computing and Services
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• v.8 no.2
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• pp.77-87
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• 2007

A typical VOD service allows that a number of remote clients playback a desired video from a large collection of videos stored in one or more video servers. The main bottleneck for a VOD service is the network bandwidth connecting to the VOD server to the client due to the high bandwidth requirements. Many previous researches have shown that VOD server can be greatly improved through the use of multicast, broadcast, or P2P scheme. Broadcast is one of the most efficient techniques because it can transmit a stream to many users without additional network bandwidth. But the broadcast has long latency time. In order to overcome the drawback, in this paper, we propose P2Prefix broadcast scheme that can solve the service latency time, which is the problem of broadcast scheme, by using P2P caching as well as minimizing the client buffer requirement.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.6
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• pp.125-132
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• 2015

This paper presents an event data delivery scheme for wireless sensor networks that use a GTS-based channel allocation scheme. Many sensor nodes can share a GTS channel for sending their normal data to the sink node. When there is an event at a node, the node makes a temporal route to the sink node and the nodes of the route can use the GTS channel in a privileged access. This scheme controls the backoff number effectively so the data delivery priority is given to the nodes of that route. Simulation results show that the event data delivery of the proposed scheme outperforms at the end-to-end transfer delay and jitter characteristics. The proposed scheme can effectively gather the event data using the guaranteed GTS channel of the route in proposed scheme.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.18-24
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• 2013

Network coding has been extensively studied to increase the network throughput by exploiting the broadcast and overhearing capabilities. In this paper, we formulate a network utility maximization problem to improve the network utility in multichannel, multiradio and multisession wireless multihop network with intrasession network coding. To find the solution of this problem, we propose a congestion control, distributed rate control, and heuristic resource allocation algorithm. We find the network utility and evaluate the performance in multichannel, multiradio and multisession environment by using MATLAB. Finally, the results show that the proposed schemes can achieve throughput improvement by performing the network utility optimization in wireless multihop network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.6
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• pp.672-677
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• 2016

Development of Internet has been successfully inspired with extensive deployment of the network technology and application. However, increases in Internet usage had caused a lot of traffic overload in these days. Thus, we need a continuous research and development on the network virtualization for effective resource allocation. In this paper, we propose a minimal cost virtual network mapping algorithm using Piecewise Linear Cost Function. We exploited an algorithm with Linear Programming and D-VINE for node mapping, and Shortest Path Algorithm based on linear programming solution is used for link mapping. In this way, we compared and analyzed the average cost for arrival rate of VN request with linear and tree structure. Simulation results show that the average cost of our algorithm shows better efficiency than ViNEyard.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.9
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• pp.1001-1009
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• 2016

In LTE networks, the base station transmits control information over the physical downlink control channel (PDCCH) including scheduling grants, which are used to indicate the resources that the user equipment uses to send data to the base station. Because the size of the PDCCH message and the number of the PDCCH transmissions increase in proportion to the number of user equipments, the overhead of the PDCCH may cause serious network congestion problems in the narrowband LTE (NB-LTE) system. This paper proposes the compact PDCCH information bit allocation to reduce the size of the PDCCH message and evaluates the performance of the semi-persistent scheduling (SPS) in the NB-LTE system. The simulation results show that the SPS can significantly reduce the signaling overhead of the PDCCH and therefore increase the system utilization.

• The Transactions of the Korea Information Processing Society
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• v.6 no.2
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• pp.385-395
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• 1999

Video-On-demand system provides electronic video rental services from remote video servers on a broadband communication networks. When we assume some situation that serve the same video stream by batching, each time single video stream became available at server-end side, we face the problem that what video stream to be scheduled at what time instant. Hence, in order to manage the resource bandwidth which is different at each stream, the policy of channel allocation became important factor. In this work, we proposed three type of scheduling policies with queueing, as are cumulative Waiting Time(CWT), Mean Waiting Time(MWT) and Predictable Popular Factor(PPF). While CWT policy is good for popular video, MWT policy was good for non-popular video. Also, we know that PPT policy has some fairness for average wait time and reneging rate of user requests.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.3
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• pp.41-52
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• 2010

The purpose of this paper is to evaluate visitor satisfaction(VS) in waterfront parks in terms of resources, facilities, embodiment of theme(ET), site composition(SC), relaxation activity space(RAS), and dynamic activity space(DAS), which are supply-side components in the planning process of waterfront parks, in order to answer the research question; 'How is visitor satisfaction of waterfront parks determined?' After reviewing the literature on parks and the building process of waterfront parks in Korea, we constructed a conceptual framework and have ascertained a research hypothesis. We had obtained data through a questionnaire survey from 327 visitors at waterfront parks, based on the quota sampling method. We have analyzed the data using the path analysis method. We found that: 1) The direct effects of resources and facilities on VS turned out to be 0.273 and 0.306, respectively while the indirect effects are 0.114, 0.170, respectively. 2) The direct effects of SC, as a component of the planning process on VS, turned out to be 0.243 while that of ET had no affect on VS. The indirect effect of ET and SC on VS turned out to be 0.059 and 0.018, respectively. 3) The direct effects of RAS on VS turned out to be 0.129 while the indirect effects of RAS and DAS on VS turned out to be 0.002 and 0.017, respectively. 4) The size of causal effect, in order, were facilities, resources, SC, RAS, ET, and DAS. 5) Resources and facilities, as a park foundation, compose 64.84 percent of total causal effect while ET and SC have 24.04 percent and RAS and DAS have 11.12 percent, respectively. These research results imply that: 1) Existing waterfront parks should be regenerated with the embodiment of water related theme and with improved facilities for RAS and visitor programs and/or facilities for DAS. 2) The relationship among ET, SC, RAS and DAS should be increased for a significant improvement of VS, and 3) A process-oriented approach turned out to be highly useful for the development of substantive theory and methodology. It is recommended that a structural equation model on waterfront parks be developed using more empirical data and this approach be widely applied for testing its validity.

• Environmental and Resource Economics Review
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• v.14 no.4
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• pp.817-838
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• 2005

In this paper, the resource adequacy as well as the optimum fuel mix is obtained by the following procedures. First, the regulation body, the government agency, determine the reliability index as well as the optimum portfolio of the fuel mix during the planning horizon. Here, the resources with the characteristics of public goods such as demand-side management, renewable resources are assigned in advance. Also, the optimum portfolio is determined by reflecting the economics, environmental characteristics, public acceptance, regional supply and demand, etc. Second, the government announces the required amount of each fuel-type new resources during the planning horizon and the market participants bid to the government based on their own estimated fixed cost. Here, the government announces the winners of the each auction by plant type and the guaranteed fixed cost is determined by the marginal auction price by plant type. Third, the energy market is run and the surplus of each plant except their cost (guaranteed fixed cost and operating cost) is withdrew by the regulatory body. Here, to induce the generators to reduce their operating cost some incentives for each generator is given based on their performance. The performance is determined by the mechanism of the performance-based regulation (PBR). Here the free-riding performance should be subtracted to guarantee the transparent competition. Although the suggested mechanism looks like very regulated one, it provides two mechanism of the competition. That is, one is in the resource construction auction and the other is in the energy spot market. Also the advantages of the proposed method are it guarantee the proper resource adequacy as well as the desired fuel mix. However, this mechanism should be sustained during the transient period of the deregulation only. Therefore, generation resource planning procedure and market mechanisms are suggested to minimize possible stranded costs.