• Journal of Sensor Science and Technology
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• v.17 no.1
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• pp.9-14
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• 2008

In this paper, the gas responses of tungsten oxide films prepared by anodic reaction was discussed. Sensing electrodes and heating electrodes were patterned by photolithography method on quartz substrate. Porous tungsten oxide was fabricated in electrolyte solutions of 5 % HF (HF :$C_2H_6OH:H_2O$=3 : 2 : 20) by anodic reaction. The anodic reaction with metal (platinum wire) as a cathode and the sensing device as an anode was conducted under the various reaction times (1-10 min) at 10 mA/$cm^2$ The surface structure and morphology of the fabricated sensor have been analysed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). All the peaks of XRD results were well indexed to the pure phase pattern. The average diameter of the porous tungsten oxide surface were ranged about 100 nm. The fabricaed sensor showed good sensitivity to 200 ppm toluene at operating temperature of $250^{\circ}C$.

• Journal of Korea Multimedia Society
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• v.17 no.12
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• pp.1461-1472
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• 2014

Recently, smart devices has been spreaded and the definition of RFID/USN(Radio Frequency Identification/Ubiquitous Sensor Network) technology has also extended. So, originally, human is an agent of communications but now, 'the things' are also an agent of communication. That is, Internet of Things(IoT). IoT is very big IT infra technology that is based on wire-wireless network technologies such as Bluetooth and Wi-Fi. However, in reality, IoT service that can provide various meaning and integrate smoothly is not appear yet. To solve these problems of IoT, we implemented Publish/Subscribe system, which operate in Zigbee based wireless sensor network by using MQTT-SN protocol. Moreover, this system can operate with combining MQTT system that is already existed in external Internet network so, extensibility and flexibility aspect is excellent. We show that possibility of IoT services that is combined between different heterogeneous network through the MQTT-SN.

• Journal of Sensor Science and Technology
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• v.16 no.5
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• pp.389-393
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• 2007

Soft ferromagnetic materials are very useful for many sensors using magnetic materials demanding high permeability, low coercivity and low hysteresis loss. Among them, FeCoSiBNi amorphous magnetic films show a good impedance change (about 5.01 %/Oe, at 10 MHz) by the exterinal magnetic field in this experiment. The magnetic films are produced by melt-spun method, one of the rapid solidification process. Ribbon shape wires were made from the films, and let them annealed in DC magnetic field to increase the maximum Giant Magneto Impedance ratio. Field annealing decreases the stress and changes the effective anisotropy. Thus, we can find that the impedance change (200.47 %) is improved and the fabricated magnetic wire has characteristics of good sensor element.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.224-237
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• 1995

An ECU(Electronic Control Unit) with 16 bit microcomputer has been developed. This system includes hardware and software for more precise control on fuel injection, ignition timing, and idle speed. This control system employs an air flow sensor of the hot wire type, a direct ignition system, an idle speed control system using a solenoid valve, and a crank angle sensor. Especially, the crank angle sensor provides two separate signals: One is the position signal(POS) which indicates 180 degree pulses per revolution, and the other is the reference signla(REF) that represents each cylinder individually. The conventional engine control system requires at least two engine revolutions in order to identify the cylinder number. However, the developed engine control system can recognize the cylinder number within a quarter of an engine revolution. Therfore, the developed engine control system has been able to control fuel injection and ignition timing more quickly and accurately, Furthermore, the number of misfire reduces during the cold start.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.341-348
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• 2009

Various types of micro cone penetrometers have been developed by using strain gages for the layered soil detection. Strain gages, however, are affected by several factors such as temperature, self heating and lead wire length. In this study, micro cone penetrometers with 3~7mm in diameter, are developed by using FBG sensor to overcome the defects of the strain gage, and compensate the effect of temperature during penetration. In order to verifiy the accuracy and reliability of the developed FBG cone, the cone penetration test is performed on the layered soil. The tip resistance of FBG snesor shows excellent sensitivity, and can detect the interface of the layered soils with higher resolution. In addition, the 3mm micro cone penetrometer which is impossible cone diameter by using strain gages presents much higher sensitivity than the 7mm cone penetrometer. This study suggests that FBG sensor is a useful sensor for manufaturing the ultra small sized cone, and effectively detects the interface of the layered soil.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.4
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• pp.486-493
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• 2000

Flow mechanism around air flow sensor of electronic control engine, especially Karman vortex type, was investigated experimentally. The two-dimensional flow characteristics in the intermediate wake region behind a triangular vortex-generator respectively apex forward facing, apex backward facing and vertical flat plates following after apex forward facing(i.e vortex-flowmeter) were investigated at Reynolods number of $ReH=1.4\times10^4$; H is the width of a triangular vortex-generator. The vortex shedding frequency for wide Reynolds number from $7\times10^3$ to $2.1\times10^4$ was also surveyed. The velocity component was measured by X-type hot wire anemometer at 8H downstream from the bluff body. The coherent structure of the intermediate wake behind a bluff body was obtained by conditional phase average technique. As a result, it was verified that the vertical flat plates following after apex forward triangular vortex-generator make not only more linear relation between free stream velocity and vortex shedding frequency but also more periodic vortex in the vicinity of the center of wake.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.569-572
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• 2005

A generation to have felt convenience of a network by a development of Internet is pressing for realization of a wireless network. However, security of wireless network must begin with an attack to be good at all expectations. especially considred from L1 layer to L7 layer. Wireless Network weaker than wire because smuggle through various sensor terminal and invasion of radio waves netwwork Wireless network recognizes a security proposal of physical, network application layer, and is going to discuss a security development point of wiress network from now on.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.543-544
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• 2007

This paper introduce methods and analysis of a simple wireless sensor concept for detecting and locating faults as well as for load monitoring are presented. The concept is based on distributed wireless sensors that are attached to the incoming and outgoing power lines of secondary substations. A sensor measures only phase current characteristics of the wire it is attached to, is not synchronized to other sensors and does not need configuration of triggering levels. The main novelty of the concept is in detecting and locating faults by combining power distribution network characteristics on system level with low power sampling methods for individual sensors. This concept enables the sensor design to be simple, energy efficient and thus applicable in new installations and for retrofit purposes in both overhead and underground electrical distribution systems.

• Journal of IKEEE
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• v.23 no.1
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• pp.159-163
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• 2019

The food service industry has been grown due to improvement of living standards. In addition, the demand for frozen food delivery is increasing day by day at online/offline and the refrigerated vehicles are used in most of these food distributions. One of the most important factors in a refrigerated car is to measure the temperature accurately. Conventional temperature recording systems are generally connected directly to temperature sensor modules. Since the temperature data are transmitted to the temperature recorder by using the electric wire, there is a disadvantage that the resistance error must be compensated according to the cable length. In this paper, we propose a method to correct errors due to cable resistance using digital processing and CAN (Controller Area Network) communication. We use PT-1000 platinum sensor to increase the accuracy of the temperature measurement.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.2
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• pp.155-159
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• 2022

Smart livestock, which combines information and communication technology (ICT) with livestock, can be said to be an effective solution to existing livestock problems such as productivity improvement, odors, and diseases. So far, it has hardly been universalized; thus, it is necessary to develop automation devices to reduce labor by localizing automation devices to expand the distribution of ICT technology to farms, and to advance precise specifications and health management technology using biometric information. Weighing scales currently being used in livestock farms are to prevent the spread of diseases by diagnosis and preparation for AI and other diseases in advance, using information on the growing weight of duck breeding. However, accurate values cannot be obtained due to poor breeding conditions. In this paper, we developed a separate data transmission system kit for the weighing scale and placed the sensor on top of the weighing scale so that the sensor wire is not affected by pollutants or ducks on the floor. A display function was provided, and a method of receiving and analyzing the serial port data of the weighing device, and then transmitting them to the data collection server was implemented.