• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2769-2774
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• 2013

The key of USN(Ubiquitous Sensor Network) technology is low power wireless communication technology and proper resource allocation technology for efficient routing. The distinguished resource allocation method is needed for efficient routing in sensor network. To solve this problems, we propose an algorithm that can be adopted in USN with making up for weak points of PQ and WRR in this paper. The proposed algorithm produces the control discipline by the fuzzy theory to dynamically assign the weight of WRR scheduler with checking the Queue status of each class in sensor network. From simulation results, the proposed algorithm improves the packet loss rate of the EF class traffic to 6.5% by comparison with WRR scheduling method and that of the AF4 class traffic to 45% by comparison with PQ scheduling method.

• Journal of Sensor Science and Technology
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• v.18 no.1
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• pp.1-21
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• 2009

There have been continued effects to develop various types of chemical sensors according to the demands in many application fields such as safety, pollution, environment, medical engineering and food industries etc. In this review, the author intended to cover the general aspects of chemical sensors, including the history of the development, the classification, the sensing properties, and the types and application examples. And the future outlook of the chemical sensor technology, focusing on the advanced materials, high technology fusion, miniaturized intelligent system and ubiquitous sensor networks etc., has been described.

• Journal of Sensor Science and Technology
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• v.17 no.1
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• pp.53-60
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• 2008

Localization is the most important functions in mobile robots. There are so many approaches to realize this essential function in wheel based mobile robots, but it is not easy to find similar examples in small underwater robots. It is presented the sonar localization system using ubiquitous sensor network for a fish robot in this paper. A fish robot uses GPS and sonar system to find exact localization. Although GPS is essential tool to obtain positional information, this device doesn't provide reasonable resolution in localization. To obtain more precise localization information, we use several Ubiquitous Sensor Networks (USN) motes with sonar system. Experimental results show that a fish robot obtains more detailed positional information.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.1
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• pp.186-192
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• 2009

With the proliferation of ubiquitous computing we have witnessed the wide application of many wireless sensor networks into various areas because of easy installations and low-cost merits. The commercially available equipments for monitoring and predicting cracks in the mountain regions are still burden for us in terms of the installation complexity and the cost. Alternatively we in this paper design and implement a pilot slop-crack monitoring and prediction system which is based on low-cost commercial sensor networks. The proposed system is easy to install on cliffs, slopes, rocks, and banks and may minimize the destruction of the original geographical forms. Expected is that its installation and maintenance costs may reduce to the half of those of existing systems.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.33-34
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• 2007

LBS has many issues of wireless sensor networks and mobile communication parts. Location tracking or location sensing will be the opening of ubiquitous society's a big challenge and the beginning of infinite ubiquitous society's a chance. The purpose of this paper is study of sensing rate per reader antenna's placement and tag location and placement using RFID as location reference point with many advantages for location detection.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.529-532
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• 2011

Recently research efforts for ubiquitous technology that includes RFID(Radio Frequency Deification and sensor networks are conducted very actively The architectural framework of the USN sensor network discovery service. The survey of the USN technology is conducted on four technological visions that contain USN system technology USN networking technology and USN middleware along with the service platform, With respect to each technological division domestic and worldwide leading research projects are primarily explored with their technical features and research projects are primarily explored with their technical features and research outputs. Boasted on the result of the survey we establish a USN software model that includes data sensing, sensor data storage sensor data storage sensor data naming and sensor feed name service. This main objective of this model is to provide a reference model for the facilitation of USN application developments.

• ETRI Journal
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• v.34 no.5
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• pp.713-718
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• 2012

Sensor nodes in ubiquitous sensor networks require autonomous replacement of deteriorated gas sensors with reserved sensors, which has led us to develop an encapsulation technique to avoid poisoning the reserved sensors and an autonomous activation technique to replace a deteriorated sensor with a reserved sensor. Encapsulations of $In_2O_3$ nanoparticles with poly(ethylene-co-vinyl alcohol) (EVOH) or polyvinylidene difluoride (PVDF) as gas barrier layers are reported. The EVOH or PVDF films are used for an encapsulation of $In_2O_3$ as a sensing material and are effective in blocking $In_2O_3$ from contacting formaldehyde (HCHO) gas. The activation process of $In_2O_3$ by removing the EVOH through heating is effective. However, the thermal decomposition of the PVDF affects the property of the $In_2O_3$ in terms of the gas reactivity. The response of the sensor to HCHO gas after removing the EVOH is 26%, which is not significantly different with the response of 28% in a reference sample that was not treated at all. We believe that the selection of gas barrier materials for the encapsulation and activation of $In_2O_3$ should be considered because of the ill effect the byproduct of thermal decomposition has on the sensing materials and other thermal properties of the barrier materials.

• ETRI Journal
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• v.30 no.4
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• pp.516-525
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• 2008

This paper proposes a compact, energy-efficient, and smart gas sensor platform technology for ubiquitous sensor network (USN) applications. The compact design of the platform is realized by employing silicon-on-insulator (SOI) technology. The sensing element is fully integrated with SOI CMOS circuits for signal processing and communication. Also, the micro-hotplate operates at high temperatures with extremely low power consumption, which is important for USN applications. ZnO nanowires are synthesized onto the micro-hotplate by a simple hydrothermal process and are patterned by a lift-off to form the gas sensor. The sensor was operated at $200^{\circ}C$ and showed a good response to 100 ppb $NO_2$ gas.

• Journal of the Korea Institute of Building Construction
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• v.11 no.3
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• pp.283-291
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• 2011

As the construction industry has recently been transformed by the emergence of ubiquitous and intelligent technology, there have been major changes in the management methods employed. Specifically, next-generation construction management systems have been developed that collect and analyze many pieces of information in real time by using various wireless sensors and networks. The purpose of this study is to understand the current status of Ubiquitous Sensor Networks (USN) in the construction sector, and to gain fundamental data for a system of measuring concrete curing temperature in a construction site that employs a USN. By investigating the application status of USN, it was confirmed that USN has mainly been applied to the maintenance of facilities, safety management, and quality control. In addition, a field experiment in which the curing temperature of concrete was measured using a USN was carried out to evaluate two systems with wireless sensor networks, and the applicability of these systems on site was confirmed. However, it is estimated that the embedded wireless sensor type is affected by metal equipment on site, internal battery of sensor and concrete depth, and studies to provide more stable system by USN are thus required.

• The KIPS Transactions:PartC
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• v.16C no.4
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• pp.423-438
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• 2009

The sensor network is highlighted because it is one of the essentialbase networks in the ubiquitous computing realization. Researches for providing security and efficiency are being perfomed in the various isuues because of the characteristics of sensor nodes and sensor networks. Recently, code dissemination mechanism is recognized as an important research issue since sensor nodes are in the need of updating new software or the need of modifying bugs in dynamically. Generally lots of nodes are in the sensor networks and they are ramdomly deployed in hostile environments. Thus it is especially important that the code dissemination from the base station to nodes should be processed efficienctly and securely. In this paper, we check up the recent existing code dissemination mechanisms, and comparatively analyze the requirements of the code dissemination and the characteristicsof existing mechanisms. Through the analysis, we present future research issues for the code dissemination area. This research can expedite the research on the code dissemination and improve the usability of sensor networks with efficiency and security.