• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1302-1308
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• 2010

In this study, Zigbee Sensor Node to transmit harmful gases CO and $CO_2$ information using wireless communication within the ground and underground structures were developed. Wireless communication protocol was used Zigbee Stack included IEEE 802. 15.4 MAC protocol. For wireless transmission of detected harmful gas signal from ADC of MCU was implemented Zigbee Sensor Node that was developed protocol using Serial-Port-Profile(SPP) here. The proposed Zigbee Sensor Node was verified transmission distance from experiments. Transmission distance was into 90m in experiments. Distance experiments were measured at 10m intervals using sine & pulse wave input signal at indoors. The proposed Route Sensor Node was applied mesh routing protocol. When built up USN(Ubiquitous Sensor Network)using Route Sensor Node, transmission distance was not limited. On the experimental results, harmful gas values between direct measurements and USN measurements were consistent. The semiconductor CO sensor and N-DIR $CO_2$ sensor module as a harmful sensor was used. Therefore, the proposed Zigbee Sensor Node was verified about reliability and validity to build USN for transmission of harmful gas information.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.1
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• pp.18-24
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• 2006

Reactor core and internal structures of a liquid metal reactor (LMR) can not be visually examined due to an opaque liquid sodium. The under-sodium viewing technique by using an ultrasonic wave should be applied far the visual inspection of reactor internals. In this study, an ultrasonic waveguide sensor with a strip plate has been developed for an application to the under-sodium viewing technique. The Lamb wave propagation of a waveguide sensor has been analyzed and the zero-order antisymmetric $A_0$ plate wave was selected as the application mode of the sensor. The $A_0$ plate wave can be propagated in the dispersive low frequency range by using a liquid wedge clamped to the waveguide. A new technique is presented which is capable of steering the radiation beam angle of a waveguide sensor without a mechanical movement of the sensor assembly The steering function of the ultrasonic radiation beam can be achieved by a frequency tuning method of the excitation pulse in the dispersive range of the $A_0$ mode. The technique provides an opportunity to overcome the scanning limitation of a waveguide sensor. The beam steering function has been evaluated by an experimental verification. The ultrasonic C-scanning experiments are performed in water and the feasibility of the ultrasonic waveguide sensor has been verified.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.4
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• pp.60-66
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• 2005

In this paper, we propose the basic measurement method of a 3D digitizer using a CCD camera in detail. In the localization measurement with a CCD camera, the effect of the background light and the sensitivity consideration are always problems in realizing a high precision. In this research, a new measurement principle is proposed in which the pulse compression technique known in radar is used to eliminate the effect of background light even under a low intensity light source, and the coordinate values on the CCD camera image plane are determined accurately. From the quantitative evaluation of the S/N ratio improvement and the fundamental experiment, it is verified that a substantial improvement in the S/N ratio is realized for both the background noise and the pixel noise and that a resolution of less than the pixel is sufficiently possible.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.395-398
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• 1997

Human pulse represents the physical characteristics of heart and cardiovascular system. Therefore, malfunctions and errors of heart and cardiovascular system can be determined by using an automatic diagnosis system that can detect the pulse signal. Not only will the computerised system preclude the possibilities of observational errors by giving an accurate measurement with great stability, but minimize the possibilities of misinterpretation by using an automated diagnostic logic. A new combinational fiber-optic sensor, which has a detecting part and a transmitting part was used to acquire radial pulse signal noninvasively. The development of P-5 transducer makes it possible to obtain more effective detection and obvious display of pulse signals in the aspect of reliability. Using P-5 transducer in the field of plethysomography and MAC- JIN, one of our diagnoses in Korean traditional medicine, it is expected that we can ontain quantitative and valuable information or the diagnosis of human pulses.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.145-151
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• 2012

The pulsimeter is a representative device in the oriental medicine, which can analysis a risk factor in a cardiovascular diseases. However, most of the previous methods have the limit by the contacted sate of the brachial pulse and sensor in the measuring time, the inaccuracy of detected pulse, and the difficulty of pulse analysis. Accordingly, we propose the moving pulse image analysis based pulsimeter that can acquire a pulse of patient in real time by analyzing a moving image. then this video is shot the state change of the T.S. occurred by a pulse in capillary. In order to evaluate the performance of the our pulsimeter, we measured a respective detecting-rate about the essential 5 feature-points in the pulse analysis from the detected original pulse. As a result, the proposed method is very successful.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.5
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• pp.481-485
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• 2008

In stator windings of 6.6 kV rotating machine, corona discharge, surface discharge and internal discharge are caused mainly by internal voids and insulation degradation. Also, if partial discharge occurs in inner-part of stator windings, it will be happened electromagnetic pulses at wide frequency range. In case of discharge spark, electromagnetic pulse generated from discharge source, and we can detect it by using various RF resonators as an EM sensor. In order to detect these kind of electromagnetic sources, we have designed and fabricated planar patch sensor using CST MWS simulation, and also PD signals from artificial defected cable were measured by our proposed sensor. Furthermore, HFCT was used as a reference sensor and compared with our proposed new planar patch sensor.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.241-244
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• 2009

We studied the optimization method of sensing part for measuring heart rate in wrist. In order to know optimum structure of sensing part, we measured the heart rate signal by changing the shape and size of sensor pad structure and the thickness of silicon. The shapes of structure using in experiment are Empty, Rectangle, Embossing, Length, Width. We were compared the amplitude of output signal about each shape when thickness of silicon pad is increasing from 0 to 7 mm by 1 mm.

• Proceedings of the Korean Magnestics Society Conference
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• 2013.05a
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• pp.38-40
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• 2013

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.1056-1060
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• 2012

Online monitoring system is becoming an essential element of railway traction system for utilized to condition based malignance management and various techniques currently employed in railway traction system. Among the various techniques, it is efficient to detect partial discharge signals by electromagnetic wave detection in order to detect insulation fault of rectifier. Although VHF (Very High Frequency), UHF (Ultra High Frequency) sensors were adopted to detect partial discharge of power facilities, due to characteristics of urban railway, excessive noise occurs from 500 MHz to 1.5 GHz on UHF bandwidth. In this paper a new measurement system able to monitoring the conditions of power facilities on DC substation in metro was studied and set up. The system uses UHF sensors to measure the partial discharge of the rectifier due to electric faulting and dielectric breakdown. Comparison and estimation for performance of SHF sensor which had devised to detect partial discharge signal of urban railway rectifier has conducted. In order to estimate performance of SHF sensor, we have compared the sensor with existing UHF sensor on sensitivity upon frequency bandwidth generated by pulse generator, and also we have verified performance of the SHF sensor by detection results of partial discharge signal from urban railway rectifier.

• Journal of Sensor Science and Technology
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• v.22 no.1
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• pp.84-88
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• 2013

In this paper, the low price signal generator with capability of frequency high-resolution and variable sync pulse has implemented. It fulfils well the requirements for SS-OCT of the frequency resolution less than 1Hz, frequency stability of ${\leq}{\pm}0.5Hz$/10 min and variable sync pulse output timing. Through its performance test applied to wavelength swept laser, 120 nm sweeping range and 10 mW average optical power were obtained. This shows that the realized sine-wave generator can replace the commercial high cost and high performance signal generators employed by current SS-OCT systems.