This paper analyzes the 2D and 3D distortion effects of a measured profile caused by the stylus tip radius of a stylus-type surface profilometer. On the basis of our analysis results, we propose the selection criteria for the stylus tip radius to improve the reliability of measurement results. For that purpose, a simulation algorithm has been devised and implemented for 2D and 3D measurement simulations, and the 3D surface texture used in simulation was obtained using an atomic force microscope from an actual machined surface to improve the reliability of simulation results. The simulation results were compared with the measured results from the same specimen using a roughness tester, and the validity of analysis via the simulation proposed in this study was confirmed. Cumulative power spectral analysis was performed for the 2D and 3D simulated profiles obtained from simulation. On the basis of the analysis results, an effective frequency component field was clarified using a stylus-type profilometer, and the selection criteria of the stylus tip radius for measurement were proposed considering the surface texture characteristics of the specimen.

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SUMMARYThe need for data encryption that protects sensitive data in a database has increased rapidly. However, encrypted data can no longer be efficiently queried because nearly all of the data should be decrypted. Several order-preserving encryption schemes that enable indexes to be built over encrypted data have been suggested to solve this problem. They allow any comparison operation to be directly applied to encrypted data. However, one of the main disadvantages of these schemes is that they expose sensitive data to inference attacks with order information, especially when the data are used together with unencrypted columns in the database. In this study, a new order-preserving encryption scheme that provides secure queries by hiding the order is introduced. Moreover, it provides efficient queries because any user who has the encryption key knows the order. The proposed scheme is designed to be efficient and secure in such an environment. Thus, it is possible to encrypt only sensitive data while leaving other data unencrypted. The encryption is not only robust against order exposure, but also shows high performance for any query over encrypted data. In addition, the proposed scheme provides strong updates without assumptions of the distribution of plaintext. This allows it to be integrated easily with the existing database system.

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