Ivica Lukić

Improved Bisector pruning for uncertain data mining

Uncertain data mining is well studied and very challenging task. This paper is concentrated on clustering uncertain objects with location uncertainty. Uncertain locations are described by probability density function (PDF). Number of uncertain objects can be very large and obtaining quality result within reasonable time is a challenging task. Basic clustering method is UK-means, in which all expected distances (ED) from objects to clusters are calculated. Thus UK-means is inefficient. To avoid ED calculations various pruning methods are proposed. The pruning methods are significantly more effective than UK-means method. In this paper, Improved Bisector pruning method is proposed as an improvement of clustering process.

Positioning of Public Service Systems Using Uncertain Data Clustering

Positioning of public service system is crucial and very challenging task. Proper positioning ensures that the public service system would complete its tasks to the end users. This paper is focused on finding the best location for public service system, to improve its efficiency when using uncertain data clustering. By choosing the best location for the service system the respond time can be minimised, and the given tasks could be performed in a reasonable time. Improved bisector pruning method was proposed for clustering previous data of public service system to find the best location for its application. Presented method can be used for different Public Service Systems, like traffic services, positioning of ambulance vehicles and other mobile objects. Cluster centres are used as best locations for public service systems because, cluster centres minimized total expected distance from tasks that have been set to the service system. On this way, public service system will be improved and can fulfil more tasks during the shortest period of time.

Protecting Information with Subcodstanography

In modern communication systems, one of the most challenging tasks involves the implementation of adequate methods for successful and secure transfer of confidential digital information over an unsecured communication channel. Many encryption algorithms have been developed for protection of confidential information. However, over time, flaws have been discovered even with the most sophisticated encryption algorithms. Each encryption algorithm can be decrypted within sufficient time and with sufficient resources. The possibility of decryption has increased with the development of computer technology since available computer speeds enable the decryption process based on the exhaustive data search. This has led to the development of steganography, a science which attempts to hide the very existence of confidential information. However, the stenography also has its disadvantages, listed in the paper. Hence, a new method which combines the favourable properties of cryptography based on substitution encryption and stenography is analysed in the paper. The ability of hiding the existence of confidential information comes from steganography and its encryption using a coding table makes its content undecipherable. This synergy greatly improves protection of confidential information.