• Smart Structures and Systems
• /
• v.15 no.6
• /
• pp.1543-1567
• /
• 2015

In this study, a wireless crack sensor is developed for monitoring cracks propagating in two dimensions. This sensor is developed by incorporating a laser-based optical navigation sensor board (ADNS-9500) into a smart wireless platform (Imote2). To measure crack propagation, the Imote2 sends a signal to the ADNS-9500 to collect a sequence of images reflected from the concrete surface. These acquired images can be processed in the ADNS-9500 directly (the navigation mode) or sent to Imote2 for processing (the frame capture mode). The computed crack displacement can then be transmitted wirelessly to a base station. The design and the construction of this sensor are reported herein followed by some calibration tests on one prototype sensor. Test results show that the sensor can provide sub-millimeter accuracy under sinusoidal and step movement. Also, the two modes of operation offer complementary performance as the navigation mode is more accurate in tracking large amplitude and fast crack movement while the frame capture mode is more accurate for small and slow crack movement. These results illustrate the feasibility of developing such a crack sensor as well as point out directions of further research before its actual implementation.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.2
• /
• pp.378-383
• /
• 2012

Nowadays, the study is going on develop USN(Ubiquitous Sensor Network) with diffusion of the internet and development of computer network technology. USN sensor nodes equipped with various types of sensors provide sensor information to each individual sensors. To do this there needs standardized data description language for allowing many people to use based on XML in web services environment. In this paper, USN sensor information required for application services in a standardized form to describe the sensor data representation language was designed. USN-based technology utilized in the field, and will be utilized for service activation.

• Journal of Internet Computing and Services
• /
• v.9 no.6
• /
• pp.15-25
• /
• 2008

Due to the differences between a mobile ad-hoc network and a sensor network, the pre-existing autoconfiguration for a mobile ad-hoc network cannot be simply applied to a sensor network. But. a mechanism is still necessary to assign locally unique addresses to sensor nodes efficiently. This paper proposes a hybrid IDs assignment scheme of local area sensor networks. The IDs assignment scheme of hybrid method combines a proactive IDs assignment with a reactive IDs assignment scheme. The proposed scheme considers efficient communication using reactive IDs assignment, and security for potential attacks using zone-based self-organized clustering with Byzantine Agreement in sensor networks. Thus, this paper has solved the shortage of security due to minimizing network traffic and the problem of repairing the network from the effects of an aberrant node in sensor networks.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.3
• /
• pp.188-192
• /
• 2012

In this study, a carbon nanotube (CNT) flexible strain sensor was fabricated with CNT based epoxy and rubber composites for tactile sensing. The flexible strain sensor can be fabricated as a long fibrous sensor and it also may be able to measure large deformation and contact information on a structure. The long and flexible sensor can be considered to be a continuous sensor like a dendrite of a neuron in the human body and we named the sensor as a biomimetic artificial neuron. For the application of the neuron in biomimetic engineering, an ANMS (Artificial Neuron Matrix System) was developed by means of the array of the neurons with a signal processing system. Moreover, a strain positioning algorithm was also developed to find localized tactile information of the ANMS with Labview for the application of an artificial e-skin.

• Convergence Security Journal
• /
• v.7 no.4
• /
• pp.51-60
• /
• 2007

It is important to assess vulnerability of network and information system to countermeasure against a variety of attack in effective and efficient way. But vulnerability and risk assessment methodology for network and information systems could not be directly applied to sensor networks because sensor networks have different properties compared to traditional network and information system. This paper proposes a vulnerability assessment framework for cluster based sensor networks. The vulnerability assessment for sensor networks is presented. Finally, the case study in cluster based sensor networks is described to show possibility of the framework.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.860-863
• /
• 2010

Wireless sensor networks consist of small, autonomous devices with wireless networking capabilities. In order to further increase the applicability in real world applications, minimizing energy consumption is one of the most critical issues. Therefore, accurate energy model is required for the evaluation of wireless sensor networks. In this paper, we analyze the energy consumption for wireless sensor networks. To estimate the lifetime of sensor node, we have measured the energy characteristics of sensor node based on Telosb platforms running TinyOS. Based on the proposed model, the estimated lifetime of a battery powered sensor node can use about 6.925 months for 10 times motion detection per hour.

• Transactions on Electrical and Electronic Materials
• /
• v.13 no.1
• /
• pp.27-30
• /
• 2012

This paper proposes a micro gas sensor for measuring $H_2S$ gas. This is based on a $SnO_2$-CuO multi-layer thin film. The sensor has a silicon diaphragm, micro heater, and sensing layers. The micro heater is embedded in the sensing layer in order to increase the temperature to an operating temperature. The $SnO_2$-CuO multi layer film is prepared by the alternating deposition method and thermal oxidation which uses an electron beam evaporator and a thermal furnace. To determine the effect of the number of layers, five sets of films are prepared, each with different number of layers. The sensitivities are measured by applying $H_2S$ gas. It has a concentration of 1 ppm at an operating temperature of $270^{\circ}C$. At the same total thickness, the sensitivity of the sensor with multi sensing layers was improved, compared to the sensor with one sensing layer. The sensitivity of the sensor with five layers to 1 ppm of $H_2S$ gas is approximately 68%. This is approximately 12% more than that of a sensor with one-layer.

• Journal of Korea Multimedia Society
• /
• v.12 no.12
• /
• pp.1778-1786
• /
• 2009

Many sensor network applications have been developed for smart home, disaster management, and a wide range of other applications. These applications, however, generally assume a fixed base station as well as fixed sensor nodes. Previous research on sensor networks mainly focused on efficient transmission of data from sensors to fixed sink nodes. Recently there has been active research on mobile sink nodes, sink mobility is one of the most comprehensive trends for information gathering in sensor networks, but the research of an environment where both fixed sink nodes and mobile sinks are present at the same time is rather scarce. This paper proposes a scheme for context-aware by ubiquitous devices with the sink functionality added through fixed sinks under a previously-built, cluster-based multi-hop sensor network environment. To this end, clustering of mobile devices were done based on the fixed sinks of a previously-built sensor network, and by using appropriate fixed sinks, context gathering was made possible. By mathematical comparison with TTDD routing protocol, which was proposed for mobile sinks, it was confirmed that performance increases by average 50% in energy with the number of mobile sinks, and with the number of movements by mobile devices.

• Journal of Drive and Control
• /
• v.13 no.1
• /
• pp.43-48
• /
• 2016

This paper presents a preliminary study on the pressure sensing characteristics of smart nano composites made of MWCNT (multi-walled carbon nanotube) to develop a novel pressure sensor. We fabricated the composite pressure sensor by using a solution casting process. Made of carbon smart nano composites, the sensor works by means of piezoresistivity under pressure. We built a signal processing system similar to a conventional strain gage system. The sensor voltage outputs during the experiment for the pressure sensor and the resistance changes of the MWCNT as well as the epoxy based on the smart nano composite under static pressure were fairly stable and showed quite consistent responses under lab level tests. We confirmed that the response time characteristics of MWCNT nano composites with epoxy were faster than the MWCNT/EPDM sensor under static loads.

• Journal of the Korea Society of Computer and Information
• /
• v.23 no.9
• /
• pp.113-122
• /
• 2018

In this paper, IoT(Internet of things) technology, which is the core of the 4th industrial revolution, was applied to the study of reduction of consumption current. The IoT is a sensor that collects data, a sensor communication, a gateway that processes and stores the collected data. Data application of IoT technology is applied to smart home, smart city, healthcare, smart factory, etc. and it needs to be applied to various industrial fields. By sensing the location of the sensor device, the specific functions of the gateway and the platform are turned ON and OFF to reduce the consumption current of the equipment during the OFF period. When the sensor device accesses the gateway, the specific function of the gateway is turned ON and When the device is separated from the gateway, it senses the sensitivity of the wireless signal and automatically turns off the certain functions. As a resurt, it has reduced the consumption of current. In this paper, we propose a novel system for detecting the location of sensor devices by applying IoT technology. The system implementation is realized by software based, and defines the requirements for the implementation of the sensor device gateway. The gateway automatically detects the location, movement of the device and performs necessary functions. Finally verifies the automatic detection performance of the gateway according to the location of the device. It will contribute greatly to the development of the smart city and office.