• Journal of KIISE:Computing Practices and Letters
• /
• v.10 no.1
• /
• pp.14-24
• /
• 2004

Views are essential in providing logical data independence for database systems. Object views in object-oriented/object-relational databases have requirements quite different from those of relational databases due to support for object-oriented concepts. Although many commercial object-oriented/object-relational database systems support object views, implementation techniques have not been discussed sufficiently in the literature. In this paper, we devise a technique for implementing views in object-oriented/object-relational databases and apply it to the ODYSSEUS object-relational database system. We first analyze the requirements of object views. Next, to implement object views, we extend the existing query modification algorithm that has been proposed for implementing views in relational databases. Next, we compare the features of the proposed object view with those of object views in commercial object-relational database systems. It is shown that the proposed object view supports all object-oriented concepts such as object identifiers, inheritance, methods, and composite objects, while existing object views support part of them. Last, we propose detailed techniques for implementing the extended query modification algorithm in the ODYSSEUS object-relational database system.

• The Journal of the Korea Contents Association
• /
• v.17 no.7
• /
• pp.93-100
• /
• 2017

Recently, demands for high-performance flash-based storage devices (i.e., flash SSD) have rapidly grown in social network services, cloud computing, super-computing, and enterprise storage systems. The industry and academic communities made the NVMe specification for high-performance storage devices, and NVMe-based flash SSDs can be now obtained in the market. In this article, we evaluate performance of NoSQL databases that social network services and cloud computing services heavily adopt by using NVMe-based flash SSDs. To this end, we use NVMe SSD that Samsung Electronics recently developed, and the SSD used in this study has performance up to 3.5GB/s for sequential read/write operations. We use WiredTiger for NoSQL databases, and it is a default storage engine for MongoDB. Our experimental results show that log processing in NoSQL databases is a major overhead when high-performance NVMe-based flash SSDs are used. Furthermore, we optimize components of log processing and optimized WiredTiger show up to 15 times better performance than original WiredTiger.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.5
• /
• pp.381-389
• /
• 2007

6-DOF simulation program is developed in order to increase the efficiency of the store separation analysis. This S/W is much faster than a method based on CFD(Computational Fluid Dynamics) technology, and allows the simulation of stores with fixed shape as well as with extensible wings, because it uses aerodynamic databases which are prepared beforehand. In this paper, aerodynamic databases of stores are obtained with MSAP(Multi-body Separation Analysis Program), and unsteady damping coefficients are modeled with Missile Datcom. These databases and the 6-DOF simulation program are used to predict the trajectory of an external store, while its wings are being deployed. The analysis results indicate that the safe separations of the store can be achieved not only with the wing fixed but with the wings being deployed.

• Korean Journal of Poultry Science
• /
• v.28 no.2
• /
• pp.143-153
• /
• 2001

Using bioinformatic tools for searching the massive genome databases, it is possible to Identify new genes in few minutes for initial discoveries based on evolutionary conservation, domain homology, and tissue expression patterns, followed by further verification and characterization using the bench-top works. The development of high-density two-dimensional arrays has allowed the analysis of the expression of thousands of genes simultaneously in the humans, mice, rats, yeast, and bacteria to elucidate the genes and pathways involved in physiological processes. In addition, rapid and automated protein identification is being achieved by searching protein and nucleotide sequence databases directly with data generated from mass spectrometry. Recently, analysis at the bio-chemical level such as biochemical screening and metabolic profiling (Biochemical genomics) has been introduced as an additional approach for categorical assignment of gene function. To make advantage of recent achievements in computational approaches for facilitated gene discoveries in the avian model, chicken expression sequence tags (ESTs) have been reported and deposited in the international databases. By searching EST databases, a chicken heparanase gene was identified and functionally confirmed by subsequent experiments. Using combination of sub-tractive hybridization assay and Genbank database searches, a chicken heme -binding protein family (cSOUL/HBP) was isolated in the retina and pineal gland of domestic chicken and verified by Northern blot analysis. Microarrays have identified several host genes whose expression levels are elevated following infection of chicken embryo fibroblasts (CEF) with Marek's disease virus (MDV). The ongoing process of chicken genome projects and new discoveries and breakthroughs in genomics and proteomics will no doubt reveal new and exciting information and advances in the avian research.

• The Journal of Korean Association of Computer Education
• /
• v.8 no.6
• /
• pp.113-121
• /
• 2005

Since documents on the Web are naturally partitioned into many document databases, the efficient information retrieval (IR) process requires identifying the document databases that are most likely to provide relevant documents to the query and then querying the identified document databases. We first introduce a neural net agent for such an efficient IR, and then propose the hierarchically organized multi-agent IR system in order to scale our agent with the large number of document databases. In this system, the hierarchical organization of neural net agents reduced the total training cost at an acceptable level without degrading the IR effectiveness in terms of precision and recall. In the experiment, we introduce two neural net IR systems based on single agent approach and multi-agent approach respectively, and evaluate the performance of those systems by comparing their experimental results to those of the conventional statistical systems.

• Journal of Korea Multimedia Society
• /
• v.7 no.1
• /
• pp.1-11
• /
• 2004

In this paper. we propose a storage system for XML documents using relational databases. Additional processing is required to store XML documents in the relational databases due to the discrepancy between XML structures and relational schema. This study aims to store XML documents with DTD in the relational databases. We propose the association inlining that exploits shred inlining and hybrid inlining and avoids relation fragments and excessive joins. Experiments show some improvements in the performance with the proposed method. The information of the storage structures is extracted from the simplified DTD. Existing map classes are extended in order to map various structures of XML to relational schema. Map classes are defined for various structures such as elements with multiple values, elements with multiple super elements, and elements with recursive structures through analyzing XML documents. Map files that are XML structures and used in generating SQL statements are created by using the extracted information of storage structures and map classes.

• The KIPS Transactions:PartC
• /
• v.11C no.7 s.96
• /
• pp.917-922
• /
• 2004

Mobile ad hoc networks (MANETs) are networks of mobile nodes that have no fixed network infrastructure. Since the mobile node's location changes frequently, it is an attractive area to maintain the node's location efficiently. In this paper, we present an adaptive randomized database group (ARDG) scheme to manage the mobile nodes mobility in MHANETs. The proposed scheme stores the network nodes' location in location databases to manage the nodes' mobility. When a mobile node changes its location or needs a node's location, the node randomly select some databases to update or que교 the location information. The number of the selected databases is fixed in the case of querying while the number of the databases is determined according to the node's popularity in the case of updating. We evaluated the performance of the proposed scheme using an analytical model, and compared the performance with that of the conventional randomized database group (RDG) scheme.

• Journal of KIISE:Databases
• /
• v.29 no.6
• /
• pp.429-440
• /
• 2002

Temporal databases manage time-evolving data. They provide built-in supports for efficient recording and querying of temporal data. The temporal aggregate in temporal databases is an extension of the conventional aggregate to include time concept on the domain and range of aggregation. This paper focuses on multidimensional temporal aggregation. In a multidimensional temporal aggregate, we use one or more general attributes as well as a time attribute on the range of aggregation, thus it is a useful operation for historical data warehouse, Call Data Records(CDR), etc. In this paper, we propose a structure for multidimensional temporal aggregation, called PTA-tree, and an aggregate processing method based on the PTA-tree. Through analyses and performance experiments, we also compare the PTA-tree with the simple extension of SB-tree that was proposed for temporal aggregation.

• Journal of KIISE:Databases
• /
• v.31 no.2
• /
• pp.150-162
• /
• 2004

Moving objects have characteristics that they change continuously their positions over time. The movement of moving objects should be stored on trajectories for processing past queries. Moving objects databases need to provide spatio-temporal index for handling moving objects queries like combined queries. Combined queries consist of a range query selecting trajectories within a specific range and a trajectory query extracting to parts of the whole trajectory. Access methods showing good performance in range queries have a shortcoming that the cost of processing trajectory Queries is high. On the other hand, trajectory-based index schemes like the TB-tree are not suitable for range queries because of high overlaps between index nodes. This paper proposes new TR(Trajectory Riving)-tree which is revised for efficiently processing the combined queries. This index scheme has several features like the trajectory preservation, the increase of the capacity of leaf nodes, and the logical trajectory riving in order to reduce dead space and high overlap between bounding boxes of nodes. In our Performance study, the number of node access for combined queries in TR-tree is about 25% less than the STR-tree and the TB-tree.

• Journal of Internet Computing and Services
• /
• v.4 no.1
• /
• pp.27-37
• /
• 2003

This paper presents the Web service generation system using virtual environments and databases. Main features include that the environments and databases are generated and maintained correspondingly. It means that the virtual environments are changed automatically if the databases are updated, and also that the databases are maintained accordingly as the information about the environments are modified at the scene End users can modify the property of the virtual environments in the scene directly using the VRML edit interface, which visualizes the structures of virtual environments. Each object can be accessed through the VRML editor, its property be modified directly, and the information is updated in the database automatically. Web service pages are maintained accordingly. In addition, we define a texture mapping method based on weighted view interpolation using 2 photo images for a scene. A texture mapping interface Is also provided for end users to generate realistic images themselves.