• Journal of Communications and Networks
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• v.17 no.1
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• pp.34-39
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• 2015

In opportunistic networks, it is difficult to predict when a node encounters others and how long it keeps in contact with another. Nodes continually attempt to explore neighbor nodes in the vicinity to transmit data. In battery-operated devices, this persistent exploration consumes a great deal of energy. In this paper, we propose an optimal energy-efficient neighbor discovery scheme (OPEED) that guarantees neighbor discovery within a delay bound. Through performance evaluation, we show that the OPEED scheme consumes 33%-83% less energy than other schemes.

• Journal of the Korea Safety Management & Science
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• v.17 no.4
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• pp.105-112
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• 2015

Sawmilling industry remained a high risk with the average 4.73% of industrial accidents in 2010-2012 that was eight times that of general manufacturing. Sawmilling industry had 200 industrial accidents victim in average. Manufacturing process in sawmill industry contained dangerous machinery such as conveyors, roller, saw ( band saw, circular saw) etc. It may be effective to figure out the type of industrial accidents occurred in the past and extend risk assessment which can predict hazard such as near miss when implementing exposure or potential dangers in sawmill industry. This study conducted research on the actual condition on the place of industrial accident occurrence, detailed work and contact object when injured, and injured part targeting 643 businesses which had industrial accidents in 2010-2012. As the results, RPN of general sawmill industry was the highest 'ganglip saw' with 36,157. RPN of the following order were 'moving truck' with 25,454, 'special machining operations' with 22,283. Also, probability of general sawmill industry was a lots within 1 year, while risk appeared a lots within 5 years. So, risk assessment shall be needed to emphasis on accident prevention of sawmill industry. And additional work will be needed on the risk assessment in hazard prevention work of supervisors.