• Journal of Communications and Networks
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• v.14 no.6
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• pp.619-628
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• 2012

The ZigBee network has been considered to monitor electricity usage of home appliances in the smart grid network. ZigBee, however, may suffer from a coexistence problem with wireless local area network (WLAN). In this paper, to resolve the coexistence problem between ZigBee network and WLAN, we propose a new protocol constructing a cognitive smart grid network for supporting monitoring of home appliances. In the proposed protocol, home appliances first estimates the transmission timing and channel information of WLAN by reading request to send/clear to send (RTS/CTS) frames of WLAN. Next, based on the estimated information, home appliances transmit a data at the same time as WLAN transmission. To manage the interference between WLAN and smart grid network, we propose a cognitive beamforming algorithm. The beamforming algorithm is designed to guaranteeing zero interference to WLAN while satisfying a required rate for smart metering. We also propose an energy efficient rate adaptation algorithm. By slowing down the transmission rate while satisfying an imperceptible impact of quality of service (QoS) of the receiver, the home appliance can significantly save transmit power. Numerical results show that the proposed multiple antenna technique provides reliable communications for smart metering with reduced power comparing to the simple transmission technique.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.139-148
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• 2011

This paper presents the minimum-cost network selection scheme which determines the transmission instance in the multi-band maritime communication system, so that the shipment-related real-time information can be transmitted within the maximum allowed period. The transmission instances and the corresponding network selection process are modeled by a Markov Decision Process (MDP), for the channel model in the 2-state Markov chain, which can be solved by stochastic dynamic programming. It derives the minimum-cost network selection rule, which can reduce the network cost significantly as compared with the straight-forward scheme with a periodic transmission.

• The KIPS Transactions:PartA
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• v.13A no.7 s.104
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• pp.573-580
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• 2006

The conventional transport layer protocol TCP is designed to work under condition of packet loss is due to the network congestion, so that it's suitable in the traditional wired network with fixed hosts but it's inefficient on the wireless network where the environment of fading, noise, and transmission error comes from interference. This result from the needless transmission control of the bit error is due to treats the packet loss as a packet congestion control in the wireless network. In this paper, we propose the advanced SNOOP protocol with the consecutive packet loss and TCP window control to avoid the needless congestion management algorithm in wireless network for the wireless TCP packet transmission enhancement. We verify the performance of the advanced module from the simulation experiment result.

• Journal of Internet Computing and Services
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• v.16 no.5
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• pp.11-17
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• 2015

In the general transmission power control model that is used for wearable sensor systems, if RSSI value gets out of the Target RSSI Margin, then the sink node finds new transmission power by using TPC(Transmission Power Control) Algorithm. At this time, the sink node sends the control packet to the sensor node for delivering the newly calculated transmission power. However, when the wireless network channel condition is poor, even it is consuming a lot of control packets, the sink node could not find an appropriate transmission power so it only waste of energy. Therefore, we proposed a new control packet transmission decision method that the sink node changes the transmission power when the wireless network channel condition is stabilized. It makes waste of energy decline. In this paper, we apply control packet transmission decision method to Binary TPC algorithms and analyze the results to evaluate the proposed method. We propose three methods that judge the state of wireless network channel. We experiment that methods and analysis the results.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.142-144
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• 2004

To provide more qualified data service on the HFC(Hybrid-Fiber Coaxial) access network, the channel characteristics of upstream transmission band should be carefully investigated and analysed. It will be easier to do network management if the monitoring system for noise measurement in the network is available, In this paper, noise analysis method and the frequency selection method in the upstream band for duplex transmission are suggested. And, Data aquisition device for the signal measurement Is implemented. With this network monitoring system, field test and the result from the collected data are described.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.131-132
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• 2007

In this paper, we designed and implemented bio-signals transmission and storage system using wireless sensor network based on ZigBee. Wireless sensor network is organized with routing protocol based on tree structure. The data is transmitted to monitoring system based on SIP. ZigBee will be used as various combinations with other wireless network technologies for application purposes.

• The Journal of the Korea Contents Association
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• v.6 no.7
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• pp.69-78
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• 2006

In this paper, we presents the efficiency and a transmission quality of the system which is composed of the optical elements from physical layer of the active optical ring network. For a simulation it will use the Transmissionmaker WDM and it will be able to observation a optical transmission quality of the optical transmission system. The active optical network is composed of two rings(main ring and sub-ring). It measures the BER(Bit Error Rate) quality which it follows node number from the sub ring and physical distance of the node. Performance analysis from the physical layer becomes the standard of the plan for the efficiency optimization of the active optical ring network. Consequently it will be able to compose the efficient optical transmission system which reflects the physical distance, a traffic demand quantity of each node and a number of users from actual network.

• Journal of Advanced Navigation Technology
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• v.23 no.4
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• pp.302-308
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• 2019

Aircraft data network (ADN) is a data networking for signal transmission among avionic systems in aircraft, and it mostly has been applied MIL-STD-1553B that guarantees high reliability considering its application environments. However, commercial Ethernet has been widely applied for ADN recently, and its range of applications have increased. Ethernet provides high speed of data transmission, however, it could not guarantee quality of service (QoS) so high as MIL-STD-1553B. In this paper, we propose dynamic routing and priority based data transmission schemes in order to improve the QoS of legacy Ethernet. Our propose schemes can be applied to Ethernet switch, and it is able to manage network traffic efficiently, and reduce the time for data transmission. We analyze the packet transmission time for both legacy and proposed schemes in Ethernet environments using simulation, and we show that our proposed scheme can reduce the time for data transmission compare to legacy spanning tree protocol.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.6
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• pp.1229-1234
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• 2012

In this paper, we analyze the problems that the DDS middleware, which is a standard data-centric communication interface, uses the fixed packet transmission method by the pre-defined protocol for exchanging data packets. The packet transmission method selected in a fixed manner cannot handle appropriately the increasing of resource overhead in an environment where the load of the DDS network changes dynamically. If the load on the node and network exceeds the threshold, the performance of the packet transmission may be degraded rapidly. This results in a failure of ensuring the real-time characteristic of DDS middleware. To solve this problem, we propose the scheme of the adaptive packet transmission for adjusting the transmission method in real-time based on the overhead on the DDS network.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.312-315
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• 2004

A lubricated state of an automobile transmission can not be inspected directly with eyes. Thus, it needs to develop a more general method. Wear debris can be collected from the lubricants of operating transmission of an automobile and its morphology is directly related to the fiction condition of the interacting materials from which the wear particles originated in lubricated transmission. In this paper, to identify the friction condition for transmission gear by neural network, the wear test of ball-on-disk type and the analysis of friction state were carried out for carburized SCM420 and nitrocarburized NT100 under different experimental conditions. The four shape parameters($50\%$ volumetric diameter, aspect, roundness and reflectivity) of wear debris were calculated by the image processing system. They were used as input values to identify the moving condition of transmission gear by the neural network.