• The KIPS Transactions:PartD
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• v.10D no.4
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• pp.591-602
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• 2003

Delay and discontinuance phenomenon of service are cause by sudden increase of the network communication amount and the quantity consumed of resources when Internet users are driven excessively to a conventional single large database sewer. To solve these problems, spatial database cluster consisted of several single nodes on high-speed network to offer high-performance is risen. But, research about spatial join operation that can reduce the performance of whole system in case process at single node is not achieved. So, in this paper, we propose efficient parallel spatial join processing method in a spatial database cluster system that uses data partitions and replications method that considers the characteristics of space data. Since proposed method does not need the creation step and the assignment step of tasks, and does not occur additional message transmission between cluster nodes that appear in existent parallel spatial join method, it shows performance improvement of 23% than the conventional parallel R-tree spatial join for a shared-nothing architecture about expensive spatial join queries. Also, It can minimize the response time to user because it removes redundant refinement operation at each cluster node.

• Geophysics and Geophysical Exploration
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• v.1 no.1
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• pp.49-56
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• 1998

Seismic tomography has been widely used as high resolution subsurface imaging techniques in engineering applications. Although most of the techniques have been using travel time inversion, waveform method is being driven forward owing to the progress of computational environments. Although full-waveform inversion method has been known as the best method in terms of model resolving power without high-frequency restriction and weak scattering approximation, it has practical disadvantage that it is apt to get stuck in local minimum if the initial guess is far from the actual model and it consumes so much time to calculate. In this study, 2-D full-waveform inversion algorithm in acoustic medium is developed, which uses result of traveltime tomography as initial model. From the application on synthetic data, it is proved that this approach can efficiently reduce the problem of conventional approaches: our algorithm shows much faster convergence rate and improvement of model resolution. Result of application on physical modeling data also shows much improvement. It is expected that this algorithm can be applicable to real data.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.7
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• pp.665-674
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• 2000

In data parallel programs incurring high cache locality, the choice of grain sizes affects cache performance. Though the grain sizes chosen provide fair load balance among processors, the grain sizes that ignore underlying caching effect result in address interferences between grains allocated to a processor. These address interferences appear to have a negative impact on the cache locality, since they result in cache conflict misses. To address this problem, we propose a best grain size driven from a cache size and the number of processors based on direct mapped cache's characteristic. Since the proposed method does not map the grains to the same location in the cache, cache conflict misses are reduced. Simulation results show that the proposed best grain size substantially improves the performance of tested data parallel programs through the reduction of cache misses on direct-mapped caches.

• Journal of Korean Library and Information Science Society
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• v.24
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• pp.45-79
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• 1996

Rising publication costs and declining financial resources have resulted in renewed interest among librarians in resource sharing. Although the idea of sharing resources is not new, there is a sense of urgency not seen in the past. Driven by rising publication costs and static and often shrinking budgets, librarians are embracing resource sharing as an idea whose time may finally have come. Resource sharing in electronic environments is creating a shift in the concept of the library as a warehouse of print-based collection to the idea of the library as the point of access to need information. Much of the library's material will be delivered in electronic form, or printed. In this new paradigm libraries can not be expected to su n.0, pport research from their own collections. These changes, along with improved communications, computerization of administrative functions, fax and digital delivery of articles, advancement of data storage technologies, are improving the procedures and means for delivering needed information to library users. In short, for resource sharing to be truly effective and efficient, however, automation and data communication are essential. The possibility of using full-text online databases as a su n.0, pplement to interlibrary loan for document delivery is examined. At this point, this article presents possibility of using full-text online databases as a means to interlibrary loan for document delivery. The findings of the study can be summarized as follows : First, turn-around time and the cost of getting a hard copy of a journal article from online full-text databases was comparable to the other document delivery services. Second, the use of full-text online databases should be considered as a method for promoting interlibrary loan services, as it is more cost-effective and labour saving. Third, for full-text databases to work as a document delivery system the databases must contain as many periodicals as possible and be loaded on as many systems as possible. Forth, to contain many scholarly research journals on full-text databases, we need guidelines to cover electronic document delivery, electronic reserves. Fifth, to be a full full-text database, more advanced information technologies are really needed.

• The KIPS Transactions:PartA
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• v.10A no.2
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• pp.111-122
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• 2003

Military wargame simulation models must support the HLA in order to facilitate interoperability with other simulations, and using parallel simulation engines offer efficiency in reducing system overhead generated by propelling interoperability. However, legacy military simulation model engines process events using sequential event-driven method. This is due to problems generated by parallel processing such as synchronous reference to global data domains. Additionally. using legacy simulation platforms result in insufficient utilization of multiple CPUs even if a multiple CPU system is under use. Therefore, in this paper, we propose conversing the simulation engine to an object model-based parallel simulation engine to ensure military wargame model's improved system processing capability, synchronous reference to global data domains, external simulation time processing, and the sequence of parallel-processed events during a crash recovery. The converted parallel simulation engine is designed and implemented to enable parallel execution on a multiple CPU system (SMP).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1498-1507
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• 2017

According to recent report, global mobile data traffic is expected to increase by 11 times from 2016 to 2020. Moreover, this growth is expected to be driven mainly by mobile video traffic which is expected to account for about 70% of the total mobile data traffic. To cope with enormous mobile traffic, we need to understand video traffic's characteristic. Recently, the repetitive requests of some popular content such as popular YouTube videos cause a enormous network traffic overheads. If we constitute a network with the nodes capable of content caching based on the content popularity, we can reduce the network overheads by using the cached content for every request. Through device-to-device, multicast, and helpers, the video throughput can improve about 1.5~2 times and prefix caching reduces the playback delay by about 0.2~0.5 times than the conventional method. In this paper, we introduce some recent work on content popularity-based caching techniques in wireless networks.

• Structural Engineering and Mechanics
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• v.83 no.4
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• pp.515-535
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• 2022

The strength models for fiber-reinforced polymer (FRP)-confined normal strength concrete (NC) cylinders available in the literature have been suggested based on small databases using limited variables of such structural members portraying less accuracy. The artificial neural network (ANN) is an advanced technique for precisely predicting the response of composite structures by considering a large number of parameters. The main objective of the present investigation is to develop an ANN model for the axial strength of FRP-confined NC cylinders using various parameters to give the highest accuracy of the predictions. To secure this aim, a large experimental database of 313 FRP-confined NC cylinders has been constructed from previous research investigations. An evaluation of 33 different empirical strength models has been performed using various statistical parameters (root mean squared error RMSE, mean absolute error MAE, and coefficient of determination R²) over the developed database. Then, a new ANN model using the Group Method of Data Handling (GMDH) has been proposed based on the experimental database that portrayed the highest performance as compared with the previous models with R²=0.92, RMSE=0.27, and MAE=0.33. Therefore, the suggested ANN model can accurately capture the axial strength of FRP-confined NC cylinders that can be used for the further analysis and design of such members in the construction industry.

• Journal of KIISE:Databases
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• v.32 no.4
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• pp.362-371
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• 2005

Similarity indexing and searching are well known to be difficult in high-dimensional applications such as multimedia databases. Especially, they become more difficult when multiple features have to be indexed together. In this paper, we propose a novel indexing method called the GB-index that is designed to efficiently handle complex similarity queries as well as relevance feedback in high-dimensional image databases. In order to provide the flexibility in controlling multiple features and query objects, the GB-index treats each dimension independently The efficiency of the GB-index is realized by specialized bitmap indexing that represents all objects in a database as a set of bitmaps. Main contributions of the GB-index are three-fold: (1) It provides a novel way to index high-dimensional data; (2) It efficiently handles complex similarity queries; and (3) Disjunctive queries driven by relevance feedback are efficiently treated. Empirical results demonstrate that the GB-index achieves great speedups over the sequential scan and the VA-file.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.219-235
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• 2014

With the development of the technology of underwater moving bodies, the need for developing the knowledge of surface effect interaction of free surface and underwater moving bodies is increased. Hence, the two-phase flow is a subject which is interesting for many researchers all around the world. In this paper, the non-linear free surface deformations which occur during the water-exit of a circular cylinder due to its buoyancy are solved using finite volume discretization based code, and using Volume of Fluid (VOF) scheme for solving two phase flow. Dynamic mesh model is used to simulate dynamic motion of the cylinder. In addition, the effect of cylinder mass in presence of an external force is studied. Moreover, the oblique exit and entry of a circular cylinder with two exit angles is simulated. At last, water-exit of a circular cylinder in six degrees of freedom is simulated in 3D using parallel processing. The simulation errors of present work (using VOF method) for maximum velocity and height of a circular cylinder are less than the corresponding errors of level set method reported by previous researchers. Oblique exit shows interesting results; formation of waves caused by exit of the cylinder, wave motion in horizontal direction and the air trapped between the waves are observable. In 3D simulation the visualization of water motion on the top surface of the cylinder and the free surface breaking on the front and back faces of the 3D cylinder at the exit phase are observed which cannot be seen in 2D simulation. Comparing the results, 3D simulation shows better agreement with experimental data, specially in the maximum height position of the cylinder.

• Journal of Distribution Science
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• v.14 no.11
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• pp.75-82
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• 2016

Purpose - In order for actively pursuing medium and long term policies of Gangwon region to be effectively and efficiently driven, efficacious and practical development strategies are needed. In terms of regional revitalization in most regions that are dependent on the primary industry like Gangwon-do Province, the maintaining of local community becomes difficult and there are limitations on the support from the central government and local governments. Therefore, local communities need to implement measures not only to be financially independent but also maintain and activate themselves. And community business can be adopted to be a proper strategy to cope with this change. This study drew importance of a community business model appropriate for Gangwon-do region to figure out success factors. Research design, data, and methodology - This study aimed to come up with importance of community business model for Gangwon-do region by using AHP Method. AHP Method, which was developed by Professor Saaty in 1970', is a methodology to simplify complex problems for a rational decision making. A survey targeting related public officials and expert group was carried out and a total of 30 questionnaires were collected for the analysis. Results - Analysis model used in this study was to prioritize community business models of Gangwon-do region. The second hierarchy was divided according to local restoration type, local resource utilization type, environment improvement type, and life support type. The third hierarchy consisted of 5 items such as network, the middle structure, program, government support, and human resources to measure each importance. As a result, in the second hierarchy, local resource utilization type had the highest importance. In the third hierarchy, the middle structure had the highest importance, followed by government support, program, network, and human resources. Collectively, the results suggested that important critical factors of community business model of Gangwon-do region was the importance of local resource utilization model and the middle structure. Conclusions - Not only should projects that are already operating in the region but next community business projects that are planning in the Gangwon-do region should be practically operated in view of the importance and the models derived from this study.