• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.12B
• /
• pp.1028-1036
• /
• 2006

Energy conservation is an important issue in wireless networks, especially for self-organized, low power, low data-rate impulse-radio ultra-wideband (IR-UWB) networks, where every node is a battery-driven device. To conserve energy, it is necessary to turn node into sleep state when no data exist. This paper addresses the energy consumption analysis of Direct-Sequence (DS) versus Time-Hopping (TH) multiple accesses and two kinds of sleeping protocols (slotted and unslotted) in PHY-MAC for Un networks. We introduce an analytical model for energy consumption or a node in both TH and DS multiple accesses and evaluate the energy consumption comparison between them and also the performance of the proposed sleeping protocols. Simulation results show that the energy consumption per packet of DS case is less than TH case and for slotted sleeping is less than that of unslotted one for bursty load case, but with respect to the load access delay unslotted one consumes less energy, that maximize node lifetime.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.6B
• /
• pp.316-324
• /
• 2007

In this paper we proposed an energy consumption model for IR-UWB wireless sensor networks. The model takes the advantages of PHY-MAC cross layer design, and we used slotted and un-slotted sleeping protocols to compare the energy consumption. We addressed different system design issues that are responsible to energy consumption and proposed an optimum model for the system design. We expect the slotted sleeping will consume less energy for bursty load than that of the un-slotted one. But if we consider latency, the un-slotted sleeping model performs better than the slotted sleeping case.

• Sleep Medicine and Psychophysiology
• /
• v.12 no.1
• /
• pp.23-26
• /
• 2005

Bruxism is defined as 'diurnal or nocturnal parafunctional activity including clenching, bracing, gnashing, and grinding of the teeth'. Bruxism and clenching are two of the most common contributing factors in patients with temporomandibular disorders and craniofacial pain disorders. Even though many studies report the high prevalence of bruxism, its cause is still not clear. Occlusal interference has been regarded as a major etiologic factor. Nowadays, psychological stress and sleeping disorders are generally regarded as major possible etiologic factors. More than likely, the cause is multifactoral and overlapping, which makes it difficult for the practitioner to apply comprehensive and effective management strategies. Although dentists and psychologists generally believe that effective treatment is best achieved with a better understanding of the etiology of a given disorder, for now treatment for this type of disorder must proceed without a clear understanding of etiology. To overcome this obstacle, evidence-based comprehensive management protocols based on accumulated scientific findings should be provided. In this presentation, epidemiology, etiology, and the characteristics of bruxism are reviewed. Diagnostic procedures and management strategies focused on occlusal appliances and behavioral approaches are also discussed.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.4 no.1
• /
• pp.20-24
• /
• 2009

sensor node work limited energy. It is undesirable or impossible to replace the batteries that are depleted of energy because of characteristics of the sensor network. Due to the specific energy constrained environment, MAC design for sensor networks generally has to take energy consumption as one of its primary concerns. But in sensor networks, latency has been a key factor affecting the applicability of sensor networks to some delay-sensitive applications. Therefore, we propose MAC protocols based DSMAC in this paper. Which is able to dynamically change the sleeping and duty cycle of sensors is adjusted to adapt to packet amounts in buffer. Proposed MAC has energy efficiency and low latency, compared DSMAC.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.6A
• /
• pp.506-514
• /
• 2009

To minimize energy consumption, most of MAC Protocols in WSNs exploit low duty cycling. Among those, RMAC [4] allows a node to transmit a data packet for multiple hops in a single duty cycle, which is made possible by exploiting a control frame named Pioneer (PION) in setting up the path. In this paper, we present a MAC Protocol called Hop Extended MAC (HE-MAC) that transmits the data packet for more multiple hops in a single duty cycle. It employs an EXP (Explorer) frame to set up the multiple hop transmission, which contains the information of the maximum hop that a packet can be transmitted. With the use of the information in EXP and an internal state of Ready to Receive (RTR), HEMAC extends the relay of the packet beyond the termination of the data period by two more hops compared to RMAC. Along with our proposed adaptive sleeping method, it also reduces power consumption and handles heavy traffic efficiently without experiencing packet inversion observed in RMAC. We analytically obtain the packet delivery latency in HE-MAC and evaluate the performance through ns-2 simulations. Compared to RMAC, HE-MAC achieves 14% less power consumption and 20% less packet delay on average for a random topology of 300 nodes.