8,076 research outputs found

    Database Security System for Applying Sophisticated Access Control via Database Firewall Server

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    Database security, privacy, access control, database firewall, data break masking Recently, information leakage incidents have occurred due to database security vulnerabilities. The administrators in the traditional database access control methods grant simple permissions to users for accessing database objects. Even though they tried to apply more strict permissions in recent database systems, it was difficult to properly adopt sophisticated access control policies to commercial databases due to performance degradations. This paper proposes a database security system including a database firewall server as an enhanced database access control system which can efficiently enforce sophisticated security policies to provide database with confidentiality using a data masking technique for diverse conditions such as the date, time, SQL string, and table columns to database systems

    Limits of Binaries That Can Be Characterized by Gravitational Microlensing

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    Due to the high efficiency of planet detections, current microlensing planet searches focus on high-magnification events. High-magnification events are sensitive to remote binary companions as well and thus a sample of wide-separation binaries are expected to be collected as a byproduct. In this paper, we show that characterizing binaries for a portion of this sample will be difficult due to the degeneracy of the binary-lensing parameters. This degeneracy arises because the perturbation induced by the binary companion is well approximated by the Chang-Refsdal lensing for binaries with separations greater than a certain limit. For binaries composed of equal mass lenses, we find that the lens binarity can be noticed up to the separations of ∌60\sim 60 times of the Einstein radius corresponding to the mass of each lens. Among these binaries, however, we find that the lensing parameters can be determined only for a portion of binaries with separations less than ∌20\sim 20 times of the Einstein radius.Comment: 5 pages, 3 figures, 1 tabl

    Analysis of triterpenoids, carotenoids, and phenylpropanoids in the flowers, leaves, roots, and stems of white bitter melon (Cucurbitaceae, Momordica charantia)

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    Purpose: To evaluate the contents of carotenoids, triterpenoids, and phenylpropanoids in different parts of white bitter melon.Methods: We evaluated the accumulation of 2 triterpenoids, 10 carotenoids, and 11 phenylpropanoids in different parts of white bitter melon, including fruits at four different developmental stages using HPLC.Results: Charantin, lutein, and rutin were the main triterpenoids, carotenoids, and phenylpropanoids, respectively. The accumulation of triterpenoids (momordicine and charantin), carotenoids (antheraxanthin, lutein, violaxanthin, α-carotene, and ÎČ-carotene), and phenylpropanoids (caffeic acid, chlorogenic acid, epicatechin, gallic acid, p-coumaric acid, rutin, and trans-cinnamic acid) was high inthe leaves and/or flowers, which are exposed to direct sunlight, but low in the roots.Conclusion: Most of the analyzed components were accumulated at high levels in the leaves and/or flowers. These results will help exploit the compounds in various parts of white bitter melon that are beneficial for human health. Keywords: Momordica charantia, Bitter melon, Triterpenoid, Carotenoid, Phenylpropanoi

    HOW CAN WE TEACH STUDENT TO ESTIMATE VERTICAL JUMP HEIGHTS USING GROUND REACTION FORCE DATA

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    The purpose of this study was to estimate vertical jump heights using ground reaction force (GRF) data and to suggest one practical example of biomechanical theory application to a real human motion. Vertical jump heights of impulse and flight time method were statistically smaller than three-dimensional video method. The causes of height differences seemed mainly from the fact that impulse was used to move jumper into the horizontal direction as well as into the vertical direction. Other important factors for accurate height calculation are jumper's mass and threshold value of GRF data collection. Vertical jump height calculation with GRF data showed an example of practical application of biomechanical theory to human motion and demonstrated a way of GRF equipment use for effective biomechanical theory education
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