• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.6
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• pp.616-625
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• 2011

Ensuring the designed prestress force is very important for the safety of prestressed concrete bridge. The loss of prestress force in tendon could significantly reduce load carrying capacity of the structure. In this study, an automated prestress-loss monitoring system for prestressed concrete girder using PZT-interface and wireless impedance sensor node is presented. The following approaches are carried out to achieve the objective. Firstly, wireless impedance sensor nodes are designed for automated impedance-based monitoring technique. The sensor node is mounted on the high-performance Imote2 sensor platform to fulfill high operating speed, low power requirement and large storage memory. Secondly, a smart PZT-interface designed for monitoring prestress force is described. A linear regression model is established to predict prestress-loss. Finally, a system of the PZT-interface interacted with the wireless sensor node is evaluated from a lab-scale tendon-anchorage connection of a prestressed concrete girder.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.21-28
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• 2021

In this paper, a novel data transferring method is introduced that can transmit sensor data without using data bandwidth or an extra-processing cycle in a delay insensitive network. The proposed method uses human devices as Mules, does not disturb the device owner for permission, and saves energy while transferring sensor data to the collection hub in a wireless sensor network. This paper uses IP addressing technique as the data transferring mechanism by embedding the sensor data with the IP address of a Mule. The collection hub uses the ARP sequence method to extract the embedded data from the IP address. The proposed method follows WiFi standard in its every step and ends when data collection is over. Every step of the proposed method is discussed in detail with the help of figures in the paper.

• Journal of Sensor Science and Technology
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• v.28 no.3
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• pp.152-156
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• 2019

An ultraviolet (UV) image sensor is an extremely important optoelectronic device used in scientific and medical applications because it can detect images that cannot be obtained using visible or infrared image sensors. Because photodetectors and transistors are based on different materials, conventional UV imaging devices, which have a hybrid-type structure, require additional complex processes such as a backside etching of a GaN epi-wafer and a wafer-to-wafer bonding for the fabrication of the image sensors. In this study, we developed a monolithic GaN UV passive pixel sensor (PPS) by integrating a GaN-based Schottky-barrier type transistor and a GaN UV photodetector on a wafer. Both individual devices show good electrical and photoresponse characteristics, and the fabricated UV PPS was successfully operated under UV irradiation conditions with a high on/off extinction ratio of as high as $10^3$. This integration technique of a single pixel sensor will be a breakthrough for the development of GaN-based optoelectronic integrated circuits.

• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.80-88
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• 1999

This paper deals with the position determination problem of stereo camera systems used as a sensor for 3D robotic manipulation. Stereo cameras having parallel rays of sight and been set up on the same baseline are assumed. The distance between the sensor and the space measured is determined so as to get insensitive parameters to the uncertainty of control points used for calibration and to satisfy the error condition set by considering the repeatability of the robot. The baseline width is determined by minimizing the mutual effect of 3D positional error and stereo image coordinate error. Unlike existing techniques, the technique proposed here is developed without complicated constraints and modelling process of the object to be observed. Thus, the technique of this paper is more general and its effectiveness is proved by simulation.

• Journal of Advanced Navigation Technology
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• v.13 no.5
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• pp.699-704
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• 2009

The requirements of disaster prevention have been constantly increasing on highly disaster frequency by Global warming and environmental destruction. The damage occur more highly, especially when it's on the localized change of weather. It requires that we have methods of disaster prevention locally. In this paper, we design and implement a breakwater disaster prevention system integrated wireless sensor technique for the shore breakwater of East Sea that is raised anxiety about an accident occurrence due to stormy weather. The provided disaster prevention system perceive the seriousness of the situation that is chance of that happening by the information of realtime remote situation and a prediction system so that it could be of some help to reduce the damage of disaster and the cost of recovery.

• Journal of Advanced Navigation Technology
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• v.12 no.2
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• pp.109-114
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• 2008

As the Ubiquitous times approach, an interest regarding a Ubiquitous sensor network to be the only during key technology is rising. Currently, The fast development which radio communication technique is creating new services from the industry sector which is various from convenient characteristic and the ease characteristic side. Specially, rise and development of the radio communication technique which is various from environment monitor ring field makes to be improved about sharp curtailment of establishment and logistics relation expense, and collection period of the data which occurs real-time from site, reliability and delivery characteristic. But continuous application and the success about the environment monitor ring field of radio communication technique will be able to trust And It is important to provide time information which is appropriate real-time.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.1
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• pp.49-57
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• 2004

The modified polyionene polyelectrolyte inks were newly prepared and applied to the humidity-sensitive membrane of humidity sensor. The films were fabricated on the alumina substrate with comb-type gold electrode using a ink-jet printing technique. The copolymers of methyl methacrylate, acrylic acid, 2-hydroxyethyl methacrylate and [(2-methacryloyloxy)ethyl]trimethylammonium chloride were also prepared for the humidity-sensing material. which was fabricated by dip-coating method. Electrical measurements under various relative humidity were performed. The humidity-sensitive characteristics of sensors obtained by ink-jet printing technique were compared with that of dip-coating method. Humidity sensors showed a decrease in resistance as an increase of relative humidity and their resistance characteristics are in a close agreement each other.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.365-372
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• 1995

A signal processing technique for interferometric fiber-optic sensors is proposed. It does not require a any special optic components such as phase modulator, $3times3$ couplers,to obtain the full sensitivity of the interferometer. Instead, it requires a reference interferometer for phase referencing and a reference mirror for intensity referencing, but intensity referencing can be done without using the r reference mirror. The new technique utilizes the frequency chirping of the laser diode to process t the sensor signal with both wide dynamic range and high sensitivity of the interferometer. It was a applied to an internal-mirrored FP interferometric temperature sensor to obtain the system noise of $4\times10^{-3\circ}C$ from I cm FP Interferometor sensor device.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.447-450
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• 2005

This paper describes an implementation of system based on ZIGBEE wireless communication technique to prevent for diseases of skin ailments and respiratory ailments as sensing the air pollutions that breaks out in the inside and purifying. ZIGBEE wireless communication technique has features - low battery consumption, low cost, acceptance of the maximum 256 node and simple protocol structure of below 32Kbyte. Hardware platform is implemented by using ATmega128L in ATmel corporation and 2.4GHz RF-IC CC2420 in Chipcon corporation and dust sensor(GP2Y1010AU) and gas sensor(GSBT11) that confirm degree of inside air pollution for ZIGBEE wireless communication technique.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.5
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• pp.416-422
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• 2012

This paper proposes a low power-loss current measurement using a resistor and bypass switch. Conventional current sensing method using a resistor has a disadvantage of power loss which degrades the efficiency of the entire systems. On the other hand, proposed measurement technique operating with bypass-switch connected in parallel with sensing resistor can reduce power loss significantly the current sensor. The propose measurement works for discrete-time sampling of current sensing. Even while the analog-digital conversion does not occur at the controller, the sensing voltage across the sensor still causes ohmic conduction loss without information delivery. Hence, the bypass switch bypasses the sensing current with a small amount of power loss. In this paper, a 90[W] prototype hardware has been implemented for photovoltaic MPPT experimental verification of the proposed low power-loss current measurement technique. From the results, it can be seen that PV power observation is successfully done with the proposed method.