• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.4
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• pp.379-386
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• 1992

In this paper a direction finding method which can which can estimate the direction angles of source signals impinging on the sensor array in which sensor noises are correlated is studied. This method performs the estimation of source direction angles form sensors, regardless of sensor noise correlation, by eliminating the sensor noise correlation coefficient which can be accurately estimated. Finally, this paper shows, through the computer simulation, that the proposed, method is extremely useful and superior when there exists the noise correlation between sensors, .

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1535-1537
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• 2007

A design pattern is a general solution to a commonly occurring problem. Design patterns have proven highly effective in representing, transferring, and applying the design knowledge in many engineering disciplines. However, these patterns have not addressed sensor network specifically. With a growth of sensors and sensor networks, and considering their profound applicability, there is a crucial need to articulate ones experience of application development or deployment of sensor nodes in the form of design patterns to avoid the future mistakes. This paper discusses the same issue and show applicability of design patterns in sensor networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.799-802
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• 2005

In this paper, we analyses of Key Management Protocol for Wireless Sensor Networks in Wireless Sensor Networks. Wireless sensor networks have a wide spectrum of civil military application that call for security, target surveillance in hostile environments. Typical sensors possess limited computation, energy, and memory resources; therefore the use of vastly resource consuming security mechanism is not possible. In this paper, we propose a cryptography key management protocol, which is based on identity based symmetric keying.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.1023-1026
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• 2005

In the ubiquitous computing environment, an intelligent vehicle is defined as a sensor node with a capability of intelligence and communication in a wire and wireless network space. To make it real, a lot of problems should be addressed in the aspect of vehicle mobility, in-vehicle communication, common service platform and the connection of heterogeneous networks to provide a driver with several intelligent information services beyond the time and space. In this paper, we present an intelligent information system for managing in-vehicle sensor network and a vehicle gateway for connecting the external networks. The in-vehicle sensor network connected with several sensor nodes is used to collect sensor data and control the vehicle based on CAN protocol. Each sensor node is equipped with a reusable modular node architecture, which contains a common CAN stack, a message manager and an event handler. The vehicle gateway makes vehicle control and diagnosis from a remote host possible by connecting the in-vehicle sensor network with an external network. Specifically, it gives an access to the external mobile communication network such as CDMA. Some experiments was made to find out how long it takes to communicate between a vehicle's intelligent information system and an external server in the various environment. The results show that the average response time amounts to 776ms at fixed place, 707ms at rural area and 910ms at urban area.

• Journal of KIISE:Information Networking
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• v.35 no.2
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• pp.120-129
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• 2008

The purpose of sensor network is gathering the information from sensor nodes. If there are selfish node that deliberately avoid packet forwarding to save their own energy, the sensor network has trouble to collect information smoothly. To solve this problem we suggest a mechanism which uses credit payment schema according to the amount of forwarding packets. Sensor nodes use credits to send their own message and they forward packets of other sensor nodes to get credits. To offer authenticity we combined the roles of sink node and server, also we used piggybacking not to send additional report message. The packet trace route is almost fixed because sensor node doesn't have mobility. In this case, it happens that some sensor nodes which don't receive forwarding packets therefore they can't get credit. So, we suggested the way to give more credits to these sensor nodes. Finally, we simulated the suggested mechanism to evaluate performance with ns2(network simulator). As a result, packet transmission rate was kept on a high rate and the number of arrival packets to sink node was increased. Also, we could verify that more sensor nodes live longer due to deceasing the energy consumption of sensor nodes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.1005-1018
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• 2017

This paper proposes an App Visualization (AppV) based on IoT Self-diagnosis Micro Control Unit (ISMCU) for accident prevention. It collects a current status of a vehicle through a sensor, visualizes it on a smart phone and prevents vehicles from accident. The AppV consists of 5 components. First, a Sensor Layer (SL) judges noxious gas from a current vehicle and a driver's driving habit by collecting data from various sensors such as an Accelerator Position Sensor, an O2 sensor, an Oil Pressure Sensor, etc. and computing the concentration of the CO collected by a semiconductor gas sensor. Second, a Wireless Sensor Communication Layer (WSCL) supports Zigbee, Wi-Fi, and Bluetooth protocol so that it may transfer the sensor data collected in the SL to ISMCU and the data in the ISMCU to a Mobile. Third, an ISMCU integrates the transferred sensor information and transfers the integrated result to a Mobile. Fourth, a Mobile App Block Programming Tool (MABPT) is an independent App generation tool that changes to visual data just the vehicle information which drivers want from a smart phone. Fifth, an Embedded Module (EM) records the data collected through a Smart Phone real time in a Cloud Server. Therefore, because the AppV checks a vehicle' fault and bad driving habits that are not known from sensors and performs self-diagnosis through a mobile, it can reduce time and cost spending on accidents caused by a vehicle's fault and noxious gas emitted to the outside.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.5
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• pp.870-878
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• 2008

The level of security of most sensor nodes that comprise the sensor networks is low, but because of the low computing power and small storage capacity, it is even very difficult to apply a security algorithm efficiently to the sensor nodes. Therefore, preventing the join of an illegal node to a sensor network is impossible, and the transmitting information is easily exposed and overheard when the transmitting algorithm of the sensor node is hewn. In this paper, we propose a group key management scheme for the sensor network using polar coordinates, so that the sensor nodes can deliver information securely inside a cluster and any illegal node is prevented from joining to the cluster where a sensor network is composed of many clusters. In the proposed scheme, all of the sensor nodes in a cluster set up the authentication keys based on the pivot value provided by the CH. The intensive simulations show that the proposed scheme outperforms the pair-wise scheme in terms of the secure key management and the prevention of the illegal nodes joining to the network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.2
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• pp.195-208
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• 2009

In this paper, we introduce a grid-based key pre-distribution scheme in wireless sensor networks, which aims to improve the connectivity and resiliency while maintaining a reasonable overhead. We consider simplification of the key establishment logic and enhancement of the connectivity via plat polynomial assignment on a three-dimensional grid for node allocation and keying material assignment. We demonstrate that our scheme results in improvements via a detailed discussion on the connectivity, resource usage, security features and resiliency. A comparison with other relevant works from the literature along with a demonstrated implementation on typical sensor nodes shows the feasibility of the introduced scheme and its applicability for large networks.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1302-1308
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• 2010

In this study, Zigbee Sensor Node to transmit harmful gases CO and $CO_2$ information using wireless communication within the ground and underground structures were developed. Wireless communication protocol was used Zigbee Stack included IEEE 802. 15.4 MAC protocol. For wireless transmission of detected harmful gas signal from ADC of MCU was implemented Zigbee Sensor Node that was developed protocol using Serial-Port-Profile(SPP) here. The proposed Zigbee Sensor Node was verified transmission distance from experiments. Transmission distance was into 90m in experiments. Distance experiments were measured at 10m intervals using sine & pulse wave input signal at indoors. The proposed Route Sensor Node was applied mesh routing protocol. When built up USN(Ubiquitous Sensor Network)using Route Sensor Node, transmission distance was not limited. On the experimental results, harmful gas values between direct measurements and USN measurements were consistent. The semiconductor CO sensor and N-DIR $CO_2$ sensor module as a harmful sensor was used. Therefore, the proposed Zigbee Sensor Node was verified about reliability and validity to build USN for transmission of harmful gas information.

• International Journal of Contents
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• v.8 no.2
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• pp.13-18
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• 2012

In wireless sensor networks, an energy efficient data gathering scheme is one of core technologies to process a query. The cluster-based data gathering methods minimize the energy consumption of sensor nodes by maximizing the efficiency of data aggregation. However, since the existing clustering methods consider only uniform network environments, they are not suitable for the real world applications that sensor nodes can be distributed unevenly. To solve such a problem, we propose a balanced multi-hop clustering scheme in non-uniform wireless sensor networks. The proposed scheme constructs a cluster based on the logical distance to the cluster head using a min-distance hop count. To show the superiority of our proposed scheme, we compare it with the existing clustering schemes in sensor networks. Our experimental results show that our proposed scheme prolongs about 48% lifetime over the existing methods on average.