Jae-Young Pyun

Smart digital door lock for the home automation

In this paper, we propose a smart digital door lock system for home automation. A digital door lock system is equipment that uses the digital information such as a secret code, semi-conductors, smart card, and finger prints as the method for authentication instead of the legacy key system. In our proposed system, a ZigBee module is embedded in digital door lock and the door lock acts as a central main controller of the overall home automation system. Technically, our proposed system is the network of sensor nodes and actuators with digital door lock as base station. A door lock system proposed here consists of RFID reader for user authentication, touch LCD, motor module for opening and closing of the door, sensor modules for detecting the condition inside the house, communication module, and control module for controlling other modules. Sensor nodes for environment sensing are deployed at appropriate places at home. Status of individual ZigBee module can be monitored and controlled by the centralized controller, digital door lock. As the door lock is the first and last thing people come across in entering and leaving the home respectively, the home automation function in digital door lock system enables user to conveniently control and monitor home environment and condition all at once before entering or leaving the house. Furthermore, it also allows users to remotely monitor the condition inside the house through Internet or any other public network. The biggest advantage of our proposed system over existing ones is that it can be easily installed when and where necessary without requirement of any infrastructures and proper planning.

Robust error concealment for visual communications in burst-packet-loss networks

Compressed video sequences are very vulnerable to channel disturbances when they are transmitted through the burst-packet-loss networks such as a wireless channel. An effective solution for packet loss is to perform concealment at the receiver. Most of the spatial and/or temporal concealment methods estimate the true motion vector (MV) associated with a missing block by using the MVs of the adjacent blocks. However, these methods cannot conceal effectively the missing blocks, since the neighboring blocks can be easily lost by the burst packet losses destroying a large area of coded video. In this paper, we present a robust error concealment method of estimating the true MV of the missing block by using the bidirectional motion tracking technique within neighboring frames of a damaged frame. This motion tracking technique uses the linear trajectory feature of the image block in the forward and backward prediction directions. Experimental results sow that the proposed algorithm has superior subjective and objective video quality than conventional error concealment methods in the burst-packet-loss environments.

Real life applicable fall detection system based on wireless body area network

Real-time health monitoring with wearable sensors is an active area of research. In this domain, observing the physical condition of elderly people or patients in personal environments such as home, office, and restroom has special significance because they might be unassisted in these locations. The elderly people have limited physical abilities and are more vulnerable to serious physical damages even with small accidents, e.g. fall. The falls are unpredictable and unavoidable. In case of a fall, early detection and prompt notification to emergency services is essential for quick recovery. However, the existing fall detection devices are bulky and uncomfortable to wear. Also, detection system using the devices requires the higher computation overhead to detect falls from activities of daily living (ADL). In this paper, we propose a new fall detection system using one sensor node which can be worn as a necklace to provide both the comfortable wearing and low computation overhead. The proposed necklace-shaped sensor node includes tri-axial accelerometer and gyroscope sensors to classify the behaviour and posture of the detection subject. The simulated experimental results performed 5 fall scenarios 50 times by 5 persons show that our proposed detection approach can successfully distinguish between ADL and fall, with sensitivities greater than 80% and specificities of 100%.

A hybrid routing protocol for wireless sensor networks with mobile sinks

Low power and lossy networks have been an active area of research due to their large number of potential applications in different environments like health, environment monitoring and entertainment domain. Numbers of protocols have been proposed for routing in these networks using metrics like hop count, delay, bandwidth etc. The working group of IETF has done one major contribution in form of a proactive gradient based routing protocol for low power and lossy networks (RPL). However, for a network having few mobile sinks calculating gradients using proactive approach is costly in terms of energy. This paper proposes a hybrid routing protocol for wireless sensor networks with mobile sinks. It proposes a combination of reactive and proactive approach to enhance RPL for efficiently handling movement of multiple sinks. DAGs are only maintained by nodes close to the sink within a certain zone. While the nodes outside the zone use on demand sink discovery to find the closest possible sink, without maintaining DAG. The frequency of zone creation messages and zone sizes can increase or decrease depending on the speed of sink. This helps to decrease the number of retransmissions resulting in low standing cost for maintain DAGs and enhances the network life time especially under average or high mobility of sink.

Secure Multipath Routing Scheme for Mobile Ad Hoc Network

Mobile ad hoc networks (MANETs) are collections of autonomous mobile nodes with links that are made or broken in an arbitrary way. Due to frequent node and link failures, multipath MANET is preferred than single-path MANET in many applications. Multipath routing schemes are used for achieving various goals such as robustness, reliability, and load balancing. However, before they can be successfully deployed several security threats must be addressed. Due to lack of fixed infrastructure, security in ad-hoc routing is challenging task, especially in multipath MANET. In this paper, we propose a robust multipath routing scheme for MANET and also security mechanism for such a routing scheme. We discuss security analysis for our scheme. And we conduct simulation to evaluate the cost of the proposed secure multipath routing scheme and present some preliminary results.

Track-Sector Clustering for Energy Efficient Routing in Wireless Sensor Networks

Energy conservation is one of the most discussed issues in wireless sensor network (WSN) application and protocol designs. Conventional routing protocols such as LEACH, PEGASIS, and concentric clustering scheme (CCS) try to minimize energy consumption, but the consumed energy is still high because of redundant data transmission and various distances between head nodes and base station (BS). In this paper, we propose a new routing protocol, track-sector clustering (TSC) over WSN. In the proposed TSC scheme, we divide the network into concentric circular tracks and triangular sectors. This division of tracks and sectors helps to reduce the energy consumption by minimizing redundant data transmission and providing shortest distance between head nodes and the BS. For the formation of tracks and sectors in the network, the proposed TSC requires additional computations. However, all he computations for the formation of tracks and sectors are carried out in the BS just at the beginning of the network setup. Therefore, we can achieve the goal of energy efficiency without additional energy consumption of the distributed nodes after network setup process in our proposed TSC protocol. Our simulation results showed that the proposed TSC scheme is about 9 times, 2.5 times, and 2.3 times efficient in conserving energy as compared to LEACH, PEGASIS, and CCS respectively.

Context-Aware Streaming Video System for Vertical Handover over Wireless Overlay Network

Streaming video would become a popular form of transferring video over next-generation wireless overlay networks. As transport protocol for streaming video, TCP- friendly rate control (TFRC) is generally used. Using both TCP congestion response function and current network conditions, TFRC adjusts transmission rate so as to achieve maximum TCP-friendly throughput. However, TFRC is less responsive to changes in handover between wireless overlay networks, since it was designed for applications that would prefer to maintain a slowly-changing transmission rate. Also, the transferred streaming video could be degraded owing to the service interruption time occurred during vertical handover (VHO) process. In this paper, a new cross-layer TFRC streaming video system is demonstrated for VHO over wireless overlay network. The proposed system consists of a VHO based TFRC server and a TFRC client with VHO decision function. The proposed TFRC server uses explicit VHO messages for faster rate adaptation to a new target network. Also, the proposed TFRC client decides on switching time between different overlay networks by using handoff metrics obtained from multi-layers. The simulation results show that the proposed streaming video system provides better QoS and throughput supports than the conventional TFRC scheme during VHO .

Performance evaluation of reactive routing protocols in VANET

Node movement feature of Vehicular ad hoc network (VANET) closely resembles with that of mobile ad hoc network (MANET) but its high speed mobility and unpredictable movement characteristics are the key contrasting feature from that of MANET. The similarity nature suggests that the prevailing routing protocol of MANET is very much applicable to VANET. However, on the same line, the dissimilarity characteristics result in frequent loss of connectivity. This necessitates upgradation of the existing routing protocols to adapt itself into VANET scenario. The key parameter that needs to be fed into these protocols is a realistic mobility model which contains criterion linked to speed, road intersections, traffic light effect etc. In this paper, we compare performances of reactive routing protocols named Dynamic Source Routing (DSR), Ad hoc On Demand Distance Vector (AODV) and Ad hoc On Demand Multipath Distance Vector (AOMDV) in VANET using different Mobility Models provided in VanetMobiSim framework. The performances are evaluated by varying mobility, number of sources and node speed while packet delivery fraction, end to end delay and normalized routing load are used as performance metrics. The simulations have shown that AOMDV performs comparatively better than DSR and AODV in different mobility models in terms of end to end delay as performance metric.

Real-Time Inspection System for Printed Circuit Boards

The PCB inspection system presented in this paper can detect defects including the breaks in the wires and short circuit and is significantly faster when compared to the existing techniques. The proposed inspection method is based on referential matching between the stored reference image and the test (observed) image. Block matching is performed to solve the misalignment in referential matching. In order to reduce the computational complexity, we implement the proposed algorithm using the single instruction multiple data (SIMD) instructions, so called SSE2.

Effects of Radio Triggered Sensor MAC Protocol over Wireless Sensor Network

In this paper, we present a new medium access control (MAC) protocol called Radio Triggered Sensor MAC (RTM) protocol that is expected for the next generation sensor network. The proposed RTM is a cross-layer MAC protocol which utilizes the passive radio sensor hardware for efficient medium access. The passive radio sensors harvest the energy from the wireless signal and energize itself. The passive radio sensor is responsible for waking up the sleeping node. The sensor nodes stay in the sleep mode with their normal communication radio turned off. In order to communicate with neighboring sensor nodes, a wake-up signal is transmitted. This wake-up signal energizes the passive radio sensors waking up the sensor nodes. After the data communication, the sensor nodes are turned off. We compared RTM with Sensor MAC (S-MAC) protocol under various duty cycles through simulation in Network Simulator (ns-2). The simulation results show that RTM is 2 times energy efficient than S-MAC (with 20% duty cycle) at message period of 3 secs and 6 times at message period of 15 secs. Also, the latency of RTM is very close to the latency of S-MAC without duty cycle. This MAC protocol showing less energy consumption and faster data delivery features will be very valuable to specific applications such as wireless body area network (WBAN) and security monitoring system.