• Asia pacific journal of information systems
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• v.14 no.3
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• pp.169-187
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• 2004

Self-maintainability of data warehouse(DW) views is an ability to maintain the DW views without requiring an access to (i) any underlying databases or (ii) any information beyond the DW views and the delta of the databases. With our proposed method, DW views can be updated by using only the old views and the differential files such as different files, referential integrity differential files, linked differential files, and backward-linked differential files that keep the truly relevant tuples in the delta. This method avoids accessing the underlying databases in that the method achieves self-maintainability even in preparing auxiliary information. We showed that out method can be applicable to the DW views that contain joins over relations in a star schema, a snowflake schema, or a galaxy schema.

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.1
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• pp.31-50
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• 1996

In this paper we prescribe a replication server scheme with an algorithm DRF (Differential Refresh File) to refresh multiple materialized views and replicas in distributed environments. Before sending relevant tuples in server sites to client sites, an effective tuple reduction scheme is developed as a preprocessor to reduce the transmission cost. Because it utilizes differential files with out touching base relations, the DRF scheme can help to minimize the number of locks, which enhances the system's performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.652-657
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• 2015

BitTorrent is an innovative protocol related to file-sharing and file-transferring, which allows users to receive pieces of files from multiple sharer on the Internet to make the pieces into complete files. In reality, however, free distribution of illegal or copyright related video data is counted for crime. Difficulty of regulation on the copyright of data on BitTorrent is caused by the fact that data is transferred with the pieces of files instead of the complete file formats. Therefore, the classification process of file formats of the digital contents should take precedence in order to restore digital contents from the pieces of files received from BitTorrent, and to check the violation of copyright. This study has suggested SVM classifier for the classification of digital files, which has the feature vector of histogram differential on the pieces of files. The suggested classifier has evaluated the performance with the division factor by applying the classifier to three different formats of video files.

• Restorative Dentistry and Endodontics
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• v.43 no.2
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• pp.25.1-25.10
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• 2018

Objectives: To evaluate the mechanical properties and metallurgical characteristics of the M3 Rotary and M3 Pro Gold files (United Dental). Materials and Methods: One hundred and sixty new M3 Rotary and M3 Pro Gold files (sizes 20/0.04 and 25/0.04) were used. Torque and angle of rotation at failure (n = 20) were measured according to ISO 3630-1. Cyclic fatigue resistance was tested by measuring the number of cycles to failure in an artificial stainless steel canal ($60^{\circ}$ angle of curvature and a 5-mm radius). The metallurgical characteristics were investigated by differential scanning calorimetry. Data were analyzed using analysis of variance and the Student-Newman-Keuls test. Results: Comparing the same size of the 2 different instruments, cyclic fatigue resistance was significantly higher in the M3 Pro Gold files than in the M3 Rotary files (p < 0.001). No significant difference was observed between the files in the maximum torque load, while a significantly higher angular rotation to fracture was observed for M3 Pro Gold (p < 0.05). In the DSC analysis, the M3 Pro Gold files showed one prominent peak on the heating curve and 2 prominent peaks on the cooling curve. In contrast, the M3 Rotary files showed 1 small peak on the heating curve and 1 small peak on the cooling curve. Conclusions: The M3 Pro Gold files showed greater flexibility and angular rotation than the M3 Rotary files, without decrement of their torque resistance. The superior flexibility of M3 Pro Gold files can be attributed to their martensite phase.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.10a
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• pp.93-95
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• 1996

A replication server is considered to be one of the most effective tools to cope with the problems that may be caused by the complex data replications in distributed database systems. In the distributed environment, locking a table is inevitable and it is the main reason to coerce the system practically. This paper presents an Asynchronous Replicator Scheme (ARS) that basically utilizes the system log as files named differential files to refresh the distributed data files with complicated queries, and that it prevents (normally, huge) base tables from being locked. We take join operations as the complicated queries, not only because the join operation covers almost all the operations, but also because it is one of the most time-consuming and data intensive operations in query processings.

• Asia pacific journal of information systems
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• v.5 no.2
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• pp.131-142
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• 1995

In distributed database systems materialized views are useful to solve many problems caused by data replication. This paper deals with the problem of updating materialized views incluing join operations. We use a differential update which uses logs that record the change of base tables in certain periods. This method avoids locking of the base tables so that it makes the system more efficient. We update materialized views periodically to save the updating cost envolved. A screen test is applied to differential files to eliminate tuples that are irrelevant to any of the views being updated. Using these methods, a detailed procedure is addressed to refresh materialized views. Then we show that our update procedure performs better than a semijoin approach.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.379-386
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• 2001

Piled raft foundations are usually used to reduce total and differential settlements of superstructures. In the piled raft foundations, the raft is often on its own able to provide adequate bearing capacity and only few widely spaced piles are added to the foundation to keep settlements be1ow a certain limit. In this paper, experimental studies on the load sharing ratio between piles and raft are carried out. Also, for evaluating the application of optimum design technique using a genetic algorithm, optimal locations of files are compared with the results of laboratory model tests. from tile results of laboratory model tests, there are found that the load sharing ratio between files and raft is depended on the number of piles and stiffness of raft, and the optimal locations of piles became concentrated on the middle of rafts. From these results of laboratory model tests, the optimum technique using a genetic algorithm is acknowledged to the application in the piled raft.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.268-270
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• 2001

데이터웨어하우스내에서 실체뷰는 소스 데이터에서 갱신이 발생하였을 경우 질의에 정확한 결과를 제공하기 위하여 릴레이션의 변경사항과 동일하게 갱신되어야 한다. 이 뷰를 갱신할 때 전체 릴레이션이 아닌 갱신된 부분만 이용하여 점진적으로 뷰를 관리하는 것이 효과적이다. 뷰의 점진적인 갱신 방법중에서 부가화일을 이용한 방법은 부가적으로 유지하는 정보의 양이 적고 뷰 관리 비용이 적게 든다는 장점이 있다. 이 논문에서는 이 방법에 의해 뷰를 관리할 때의성능을 평가하기 위하여 이 방법의 비용 모델을 분석적으로 제시하였으며, 이 모델을 기반으로 성능을 비교, 분석하여 부가 파일을 이용한 방법이 다른 기존의 방법보다 성능이 우수함을 보였다.

• The Journal of Information Technology and Database
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• v.3 no.2
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• pp.3-24
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• 1996

In this paper a data replicator scheme with a distributed join architecture is suggested with its cost functions and the performance results. The contribution of this scheme is not only minimizing the number of base relation locks in distributed database tables but also reducing the remote transmission amount remarkably, which will be able to embellish the distributed databse system practical. The differential files that are derived from the active log of the DBMS are mainly forcing the scheme to reduce the number of base relation locks. The amount of transportation between relevant sites could be curtailed by the tuple reduction procedures. Then we prescribe an algorithm of data replicator with its cost function and show the performance results compared with the semi-join scheme in their distributed environments.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.1
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• pp.39-53
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• 1994

To investigate the behaviour of the embankment on very soft foundation reinforced geotex- files,the laboratory model test in order to analyze the elementary effects of geotextile reinfor- cement and the finite element program analyzing the stresses and deformations characteristics was carried out. A two-dimensional nonlinear finite element program called GEOTEXT(a modification of ISBILD) for the static analysis of embankment on very soft foundation reinforced geotextiles has been developed. Both linear and nonlinear hyperbolic stress-strain soil models are inclu- ded, and incremental and stage construction can be simulated. However, the program GEO- TEXT is not developed herein as an adaptable design tool for practicing engineer. It was found that the geotextile reinforcement significantly reduced the shear stresses in the foundation and decreased the vertical differential settlements at the top of the embank- ment. This influence was more pronounced as the tensile strength of the geotextile was increased.