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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Sensor Science and Technology
Journal Basic Information
Journal DOI :
The Korean Sensors Society
Editor in Chief :
Volume & Issues
Volume 8, Issue 6 - Nov 1999
Volume 8, Issue 5 - Sep 1999
Volume 8, Issue 4 - Jul 1999
Volume 8, Issue 3 - May 1999
Volume 8, Issue 2 - Mar 1999
Volume 8, Issue 1 - Jan 1999
Selecting the target year
Development of Ultrasonic Sensors for Simultaneous Measurement of Longitudinal and Shear Waves
Kim, Yeon-Bo ; Rho, Yong-Rae ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 1~9
A study has been made on the fabrication of a dual mode(a longitudinal and shear mode) ultrasonic sensor using a single PZT piezoelectric ceramic element. We investigated the mechanism of the dual mode sensor that generated both of the longitudinal and the shear waves simultaneously with the single PZT element. Through the analysis of analytic wave propagation equations, all the possible crystal cuts have been examined to determine appropriate Euler transformation angles for efficient excitations of the dual modes. We studied the performance of a PZT element as a function of its rotation angle so that its efficiency is optimized to excite the two waves of equal strength. Experimental examination of the waveform on a delay line(STS303) setup confirms that the ultrasonic sensor can transmit and detect both longitudinal and shear waves simultaneously.
Fabrication and Characteristics of High Brightness White Emission Electroluminescent Device
Bae, Seung-Choon ; Kim, Jeong-Hwan ; Park, Sung-Kun ; Kwun, Sung-Yul ; Kim, Woo-Hyun ; Kim, Ki-Wan ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 10~15
White emission thin film electroluminescent device was fabricated using ZnS for phosphor layer and BST ferroelectric thin film for insulating layer. For fabrication conditions of BST thin film, stoichiometry of target was
, substrate temperature was
, working pressure was 30 mTorr, and A:
ratio was 9:1. At this time, dielectric constant was 209 at 1kHz frequency. For phosphor layer ZnS:Mn, ZnS:Tb, and ZnS:Ag were used. Mixing rates of activators were respectively 0.8, 0.8, and 1 wt%. Total thickness of phosphor tapers was 500 nm, thickness of lower insulating layer was 200 nm, and thickness of upper insulating layer was 400 nm. In this conditions, luminescence threshold voltage of thin film electroluminescent device was
, maximum brightness was
. Luminescence spectrum peak was observed at region of blue(450 nm), green(550 nm), and red(600 nm).
An Underwater Acoustic Transducer Responding to Frequency Shift by Doppler Effect
Kim, Jung-Whan ; Kim, Moo-Joon ; Ha, Kang-Lyeol ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 16~23
When a moving piezoelectric transducer detects an object in water, its receiving sensitivity is attenuated by Doppler effect. In this paper, a method for compensating the effect is suggested by using a newly designed condenser of which capacitance is varied according to the moving speed of the transducer. Using the method, the receiving resonant frequency of the transducer can be changed automatically. As a result, there is good agreement between the results of experiment and those of calculation. It is confirmed that the response sensitivity degradation of transducers due to Doppler effect can be compensated in the range of
Ammonia Gas Sensing Characteristics of ZnO Based Thin Film Sensor Doped with
Kim, Sung-Woo ; Choi, Woo-Chang ; Choi, Hyek-Hwan ; Lee, Myong-Kyo ; Kwon, Tae-Ha ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 24~31
Ammonia gas sensors were fabricated with ZnO-based thin films grown by RF-magnetron sputtering method. The films which were doped with
catalysts of various weight percents were grown in different sputtering gases to fabricate the sensors with a high sensitivity, low working temperature and rapid response time. To improve electrical stability, the films were aged in various conditions. The sensors doped with the catalysts and grown in oxygen sputtering gas showed the improvement of sensitivity. These exhibited the increase of surface carrier concentration and electron mobility. The sensor with 0.875wt.%
catalysts showed the maximum sensitivity of 70 in ammonia gas concentration of 160 ppm at a working temperature of
. The sensor which is aged at
for 72hrs in oxygen ambient exhibited tourer sensitivity of 57, but more stable properties, excellent linearity.
Study on the development of mesa-type humidity sensors using porous silicon layer
Kim, Seong-Jeen ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 32~37
A capacitance-type humidity sensor with mesa structure in which porous silicon layer is used as humidity-sensing material is developed and its humidity sensing properties are measured. This sensor has a structure where two electrodes are set on the up-side of the wafer against the past typical structure having these electrodes on the up and down-side of the wafer. Therefore, the sensor can be fabricated monolithically to be more compatible with the IC process technology, and is possible to detect more correct output capacitance by removing the effect of the parasitic capacitance from the bottom layer and other junctions. To do this, the sensor was fabricated using process such as localized formation of porous silicon, oxidation of porous silicon layer, and etching of oxidized porous silicon layer. From the completed samples, the dependence of capacitance on the relative humidity of 55 to 90% more was measured at room temperature. As the result, the measured capacitance increased monotonously higher at the low frequency of 120 Hz, where the capacitance was observed to increase over 300%.
Fabrication of IC Chip for Self-Diagnostic Function of a Eight-Beam Piezoresistive Accelerometer.
Park, Chang-Hyun ; Jun, Chan-Bong ; Kang, Hee-Suk ; Kim, Jong-Jib ; Lee, Won-Tae ; Sim, Jun-Hwan ; Kim, Dong-Kwon ; Lee, Jong-Hyun ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 38~44
In this paper, we have constructed a self-diagnostic circuit which could detect erroneous signals in most cases that a eight-beam piezoresistive accelerometer were destroyed more than its one beam. To confirm the function of the circuit, PSPICE simulation was carried out. An IC chip was fabricated with a layout of KA 324 amplifier using a bipolar standard processing. After a package of the chip was sealed using a plastic package with 24 pins, the self-diagnostic characteristics were investigated. Then, the measured self-diagnostic characteristics of the circuit were compared with the PSPICE simulated result.
Variation of activation functions for accelerating the learning speed of the multilayer neural network
Lee, Byung-Do ; Lee, Min-Ho ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 45~52
In this raper, an enhanced learning method is proposed for improving the learning speed of the error back propagation learning algorithm. In order to cope with the premature saturation phenomenon at the initial learning stage, a variation scheme of active functions is introduced by using higher order functions, which does not need much increase of computation load. It naturally changes the learning rate of inter-connection weights to a large value as the derivative of sigmoid function abnormally decrease to a small value during the learning epoch. Also, we suggest the hybrid learning method incorporated the proposed method with the momentum training algorithm. Computer simulation results show that the proposed learning algorithm outperforms the conventional methods such as momentum and delta-bar-delta algorithms.
Stress characteristics of multilayer polysilicon for the fabrication of micro resonators
Choi, C.A. ; Lee, C.S. ; Jang, W.I. ; Hong, Y.S. ; Lee, J.H. ; Sohn, B.K. ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 53~62
Micro polysilicon actuators, which are widely used in the field of MEMS (Microelectromechanical System) technology, were fabricated using polysilicon thin layers. Polysilicon deposition were carried out to have symmetrical layer structures with a LPCVD (Low Pressure Chemical Vapor Deposition) system, and we have measured physical characteristics by micro test patterns, such as bridges and cantilevers to verify minimal mechanical stress and stress gradient in the polysilicon layers according to the methods of mutilayer deposition, doping, and thermal treatment, also, analyzed the properties of each specimen, which have a different process condition, by XRD, and SIMS etc.. Finally, the fabricated planar polysilicon resonator, symmetrically stacked to
thickness, showed Q of 1270 and oscillation ampitude of
under DC 15V, AC 0.05V, and 1000 mtorr pressure. The developed micro polysilicon resonator can be utilized to micro gyroscope and accelerometer sensor.
Eye Pattern Detection Using SVD and HMM Technique from CCD Camera Face Image
Jin, Kyung-Chan ; Miche, Pierre ; Park, Il-Yong ; Sohn, Byung-Gi ; Cho, Jin-Ho ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 63~68
We proposed a method of eye pattern detection in the 2-D image which was obtained by CCD video camera. To detect face region and eye pattern, we proposed pattern search network and batch SVD algorithm which had the statistical equivalence of PCA. We also used HMM to improve the accuracy of detection. As a result, we acknowledged that the proposed algorithm was superior to PCA pattern detection algorithm in computational cost and accuracy of defection. Furthermore, we evaluated that the proposed algorithm was possible in real-time face pattern detection with 2 frame images per second.
Implementation of color CCD Camera using DSP(GCB4101)
Kwon, O-Sang ; Lee, Eung-Hyuk ; Min, Hong-Ki ; Chung, Jung-Seok ; Hong, Seung-Hong ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 69~79
The research and implementation was preformed on high-resolution CCTV camera with CCD exclusive DSP conventional analog signal processor CCTV camera has its limit on auto exposure(AE), auto white balance(AWB), back light compensation(BLC) processing, severe distortion and noise of image, manual control parameter setting, etc. In our study, to resolve the problems in conventional CCTV camera, we made it possible to control AE, AWB, BLC automatically by the use of the DSP, which are used exclusively in the CCD camera produced domestically, and the microcontroller. And we utilized the function of screen display of microcontroller for the user-friendly interface to control CCD camera. And the electronic variable resister(EVR) was used to avoid setting parameters manually in the level of manufacturing process. As the result, It became possible to control parameters of the camera by program. And the cost-down effect was accomplished by improving the reliability of parameter values and reducing the efforts in setting parameters.
A Technique to Efficiently Place Sensors for Three-Dimensional Robotic Manipulation : For the Case of Stereo Cameras
Do, Yong-Tae ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 80~88
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.
Bonding Technology for PZT and Connection board using a High Frequency Heating Machine.
Lee, Jong-Hyun ; Choi, Sie-Young ;
Journal of Sensor Science and Technology , volume 8, issue 1, 1999, Pages 89~94
In this study, a new technology to bond the PZT with connection board, which is a core technology for the fabrication of medical micro high frequency sensors, was developed. Two technologies were adopted. One is bonding of In using thermal heating, he other is bonding of Pb using a high frequency heating machine. In case of thermal eating, bonding was failed because of the contaminations of In surface. But, when using high frequency healing machine, we developed good bonding characteristics at various experimental conditions and thickness of the electrode material.