• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.117-122
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• 2006

Modernized GNSS such as new GPS signals updated GLONASS and coming Galileo promises higher quality and higher reliability for users. Powerful technologies such as Internet, ubiquitous network technology and sensor network has been used to promote a safe and more secure lifestyle. This report describes experimental trials to combine these technologies namely GPS and Sensor Network into a high-performance system. GPS is used to enlarge the communication range, resolving the service area limitations, as a wider service area is required at shore areas compared to urban area. GPS position datum is also used as primary network routing information to get practical Sensor Network. Another application is the under water Sensor Network. Accurate GPS position and time are used to establish stable and high reliability underwater acoustic Sensor Network. This paper describes the background of the project 'Harbor area Marine Ubiquitous Sensor Network', preliminary consideration and testing. Radio and acoustic communication is the main focus of this preliminary experiment.

• Journal of Sensor Science and Technology
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• v.24 no.2
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• pp.119-123
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• 2015

This paper presents the inkjet-printed flexible temperature and humidity sensor(F-TH sensor) using PEDOT:PSS. The series, mesh and parallel type sensing element using PEDOT:PSS ink was printed on the overhead projector(OHP) film. The fabricated sensor of each structure has the temperature sensitivity of $140{\Omega}/^{\circ}C$, $29{\Omega}/^{\circ}C$ and $1.4{\Omega}/^{\circ}C$ with linearity, respectively. Also the fabricated sensor was not only possible to measure a temperature, but also to detect humidity. The humidity sensitivity of $400{\Omega}/%RH$, $3.4{\Omega}/%RH$ and $3{\Omega}/%RH$ with linearity, respectively. The fabricated F-TH sensor is expected for the various applications such as electronic devices, bio-healthcare, industrial field.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.207-210
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• 2005

Ubiquitous computing is one of the key technology areas in the "Project on Development of Ubiquitous computing and network technology" promoted by the Ministry of Science and Technology as a frontier business of the $21^{st}$ century in Korea, which is based on the new concept merging physical space and computer-based cyber space. With recent advances in Micro Electro Mechanical System (MEMS) technology, low cost and low-power consumption wireless micro sensor nodes have been available. Using these smart sensor nodes, there are many activities to monitor real world, for example, habitat monitoring, earthquake monitoring and so on. In this paper, we introduce web-based real environment monitoring system incorporating wireless sensor nodes. It collects sensing data produced by some wireless sensor nodes and stores them into a database system to analyze. Our environment monitoring system is composed of a networked camera and environmental sensor nodes, which are called Mica2 and developed by University of California at Berkeley. We have modified and ported network protocols over TinyOS and developed a monitoring application program using the MTS310 and MTS420 sensors that are able to observe temperature, relative humidity, light and accelerator. The sensed data can be accessed user-friendly because our environment monitoring system supports web-based user interface. Moreover, in this system, we can setup threshold values so the system supports a function to inform some anomalous events to administrators. Especially, the system shows two useful pre-processed data as a kind of practical uses: a discomfort index and a septicity index. To make both index values, the system restores related data from the database system and calculates them according to each equation relatively. We can do enormous works using wireless sensor technologies, but just environment monitoring. In this paper, we show just one of the plentiful applications using sensor technologies.

• Journal of Sensor Science and Technology
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• v.26 no.5
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• pp.301-305
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• 2017

This paper presents a wearable human health-monitoring band. The band consists of a body temperature detector (BTD) and a hear rate detector (HRD). The BTD and HRD are realized using an inkjet-printed flexible temperature sensor and a commercial heart rate sensor module, respectively. The sensitivity of the fabricated BTD was found to be $-31/^{\circ}C$ with a linearity of 99.82%. The HRD using the commercial heart rate sensor module has a good performance with a standard deviation of 0.85 between the data of a commercial smart watch and the fabricated HRD.

• Journal of Sensor Science and Technology
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• v.26 no.2
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• pp.101-106
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• 2017

A novel intravenous (IV) infusion monitoring sensor is presented to measure the drop rate in the drip chamber of an IV infusion set. It is based on a capacitive proximity sensor and detects the variation of the longitudinal electric field induced by the drop falling into the drip chamber. Unlike the conventional capacitor sensor with two semi-cylindrical conductor plates, the proximity sensor for IV monitoring is composed of a pair of conductor rings which are mounted on the outer surface of the drip chamber with a specific gap between them. The characteristics of the proximity sensor for IV monitoring were investigated through three dimensional electrostatic simulations. It showed quite superior performances in comparison with the conventional capacitor sensor. Especially, the proposed proximity sensor exhibits consistent sensitivity regardless of its mounting position on the drip chamber, operates normally though the drip chamber is tilted and shows robustness to the changes of the drop size and the drip factor of the IV infusion set. Thus, the proximity sensor for IV monitoring is more suitable for use in actual environment of IV therapy compared with the conventional capacitor sensor.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.4
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• pp.361-366
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• 2003

Most sensor array signal processing methods for multiple source localization require knowledge of the correct shape of array(the correct positions of sensors that consist array), because sensor position uncertainty can severely degrade the performance of array signal processing. In particular, it is assumed that the correct positions of the sensors are known, but the known positions may not represent the true sensor positions. Various algorithms have been proposed for 2-D sensor array shape calibration in far field environment. However, they are not available in near field. In this paper, 3-D sensor array shape calibration algorithm is proposed, which is available in near field.

• Journal of Sensor Science and Technology
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• v.18 no.3
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• pp.210-216
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• 2009

In this paper the tactile sensor system based on the bending loss of optical fiber sensor is presented. The sensor array was designed with fabric structure. The optical measuring system was composed of LED for light source and CCD camera for the signal light detector. Performance of this tactile sensor system was evaluated in various environments and compared with Harmon's design criteria. The result shows that load range is 3 g$\sim$100 g, resolution is 1.5 g, hysteresis error is 1.5%. The response linearity is good and flexibility of sensor array is excellent.

• Nuclear Engineering and Technology
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• v.50 no.4
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• pp.599-605
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• 2018

Fault diagnosis depends critically on the selection of sensors monitoring crucial process variables. Boolean network (BN) is composed of nodes and directed edges, where the node state is quantized to the Boolean values of True or False and is determined by the logical functions of the network parameters and the states of other nodes with edges directed to this node. Since BN can describe the fault propagation in a sensor network, it can be applied to propose sensor selection strategy for fault diagnosis. In this article, a sufficient condition for parameter identifiability of BN is first proposed, based on which the sufficient condition for fault identifiability of a sensor network is given. Then, the fault identifiability condition induces a sensor selection strategy for sensor selection. Finally, the theoretical result is applied to the fault diagnosis-oriented sensor selection for a nuclear heating reactor plant, and both the numerical computation and simulation results verify the feasibility of the newly built BN-based sensor selection strategy.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.3
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• pp.175-182
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• 2020

This paper introduces a study to estimate the user altitude in need of rescue in an emergency. The altitude is estimated by using the barometric pressure sensor embedded in the smartphone. Compared to GPS, which is degraded in urban or indoor environments, it has the advantage of not having spatial restrictions. With the endless development of smartphone hardware, it is possible to estimate the absolute altitude using the measured value if only the bias of the embedded barometric pressure sensor is applied. The altitude information of the person in need of rescue in an emergency is a great help in reducing rescue time. Since time is tight, we propose online calibration that provides the barometric pressure sensor bias used for altitude estimation through database. Furthermore, experiments were conducted to understand the characteristics of the barometric pressure sensor, which is greatly affected by wind. At the end, the altitude estimation performance was confirmed through an actual field tests in various floors in the building.

• Journal of Sensor Science and Technology
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• v.24 no.5
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• pp.299-305
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• 2015

Since the natural disasters such as floods, droughts, heat wave and cold wave are increasing, the need for risk management is necessary to minimize the damage with utilizing IT technology. Also, the monitoring services of disaster response type have been developed and applied. Recently, the open source hardware based on the signal of the sensor, or the monitoring studies have been carried. In this paper, by analyzing a low-cost open source hardware platform such as Beagle board, we examine the utilization of the hardware-based module for sensor monitoring.