• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.896-905
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• 2010

The sensor networks can be used attractively for various application areas. Time synchronization is important for any Ubiquitous Sensor Networks (USN) systems. USN makes extensive use of synchronized time in many contexts for data fusion. However existing time synchronization protocols are available only for homogeneous sensor nodes of USN. It needs to be extended or redesigned in order to apply to the USN with heterogeneous sensor nodes. Because heterogeneous sensor nodes have different clock sources with the SinkNode of USN, it is impossible to be synchronized global time. In addition, energy efficiency is one of the most significant factors to influence the design of sensor networks, as sensor nodes are limited in power, computational capacity, and memory. In this paper, we propose specific time synchronization based on master-slave topology for the global time synchronization of USN with heterogeneous sensor nodes. The time synchronization master nodes are always able to be synchronized with the SinkNode. Then time synchronization master nodes enable time synchronization slave nodes to be synchronized sleep periods. The proposed master-slave time synchronization for heterogeneous sensor nodes of USN is also helpful for power saving by maintaining maximum sleep time.

• Cross-Cultural Studies
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• v.50
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• pp.225-259
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• 2018

In this study, according to the Institut d'Estudis Catalan, it is noted that the traditional Catalan time telling system is essentially based on delineating time by the use of the 'quarts (=quarters)' of an hour. In this fasion, to tell the time 8:15, 8:30 and 8:45 they use '${\acute{E}}s$ un quart de nou.,' '$S{\acute{o}}n$ dos quarts de nou.,' and '$S{\acute{o}}n$ tres quarts de nou.,' but do not use constructions such as '$S{\acute{o}}n$ les vuit i quinze.,' '$S{\acute{o}}n$ les vuit i trenta/mitja.,' '$S{\acute{o}}n$ les vuit i quaranta-cinc.,' because these expressions are considered to be as dialectal variants or international notation-based variants. Moreover, the traditional Catalan time telling system does not use cardinal numbers, except in the case of 'cinc (five)' and 'deu (ten).' These linguistic phenomenon cause the invention of a unique Catalan digital watch, and has noted special designs for the creation of a Catalan analogue watch. For this reason, the quarter system in colloquial Catalan provokes an enormous interpretative ambiguity in daily routine expressions with 'quarts' like '$S{\acute{o}}n$ quarts of nou.' or 'entre dos i tres quarts' whose meaning is not delineated between sixteen and forty-four minutes. We will argue that the traditional Catalan time telling expressions do not have the use of the subtractive system, and the fraction word 'quart' lacks a specific meaning of fifteen minutes because the Catalan word 'quart' is etymologically related to the classical public bell system, not definitively to the traditional clock system.