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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 5, Issue 6 - Nov 1996
Volume 5, Issue 5 - Sep 1996
Volume 5, Issue 4 - Jul 1996
Volume 5, Issue 3 - May 1996
Volume 5, Issue 2 - Mar 1996
Volume 5, Issue 1 - Jan 1996
Selecting the target year
Study on Improvement of a LVDT for Displacement Measurements
Park, Y.T. ; Kwon, S.W. ; Gang, J.H. ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 1~8
A LVDT is an electromechanical transducer that produces an electrical output proportional to the displacement of separate movable core. A convential LVDT in construction has a disadvantage which the measurement range to the length ratio is small. This paper proposed a new type LVDT, which improved methodes of construction. The proposed LVDT and a conventional LVDT with the same dimension are simulated by FEM. In the process of the simulation and construction, the performance of two type LVDTs are evaluated. Linearity error of a conventional LVDT was
in measuring range of
and linearity error of the proposed LVDT was
in the same range. It was evident from the theoritical relationships and the experimental results that the proposed LVDT has been better performance than a convential type.
Transient Voltage Measuring System Using the Capacitive Electric Field Sensor
Lee, Bok-Hee ; Kil, Gyung-Suk ; Ju, Mun-No ; Lee, Sung-Heon ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 9~16
This paper deals with the capacitive voltage divider which can measure a transient voltages generated by operating a high voltage impulse generator. The transient voltage measuring system using the capacitive electric field sensor consists of the planar-type electric field sensor having a fast response characteristic and the wide-bandwidth voltage follower, and the input impedance of which is extremely high, about
. In order to analyze the response characteristics to a step input, the newly developed calibration method is proposed, and the error of voltage dividing ratio associated with set-up condition is investigated. Also the optimal set-up condition that is to be maintained within the range of 0.5 % is taken. From the calibration experiment, the frequency bandwidth of the transient voltage measuring system whose response time to a step input is about 15.8 ns, is from 6.37 Hz to 27.3 MHz. Therefore it is possible to measure the commercial frequency voltages as well as the transient over voltages without signal distortions.
The Improvement in Offset and Temperature Drift on Silicon Piezoresistive Pressure Sensor
Kim, Jae-Mun ; Lee, Young-Tae ; Seo, Hee-Don ; Choi, Se-Gon ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 17~24
In order to reduce the offset and its temperature drift by the different properties of the piezoresistors and the residual stress of the piezoresistive pressure sensor, a double Wheatstone-bridge pressure sensor was studied. Because the compensation bridge was arranged near by the pressure sensitive bridge, which have the similar offset component, reduction of the offset and its temperature drift was realized by the mathematical subtraction of the output of two bridges. It was configured the compensation of the offset and its temperature drift. By this compensation method, the offset and its temperature drift were reduced approximately 95% respectively. The sensitivity of the fabricated pressure sensor was
full-scale pressure range.
Ultrasonic Transducer Application for Nondestructive Testing of Continuous Cast Billets
Shin, Byoung-Chul ; Kwon, Jeong-Rock ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 25~31
Steel wires are made by elongating hot billets. If the billets have internal or surface defects, the wire can be broken during elongation process. After testing surface defect, we are testing internal defect by ultrasonic transducers. POSCO is producing two kinds of billets, hot rolled billet and cast billet. Hot rolled one is denser than cast billet. Because of the low density and rough surface, ultrasonic testing is difficult for the cast billet. Size of the transducer was related with the size and density of the billet. A transducer having 21mm long, 8.5mm wide and 0.95mm thick piezoelectric ceramic plate was best for
cast billet. Center frequency of the transducer was 2.25MHz and the focus distance was 70mm.
The Electrical Characteristics of
Yuk, Jae-Ho ; Lee, Duck-Chool ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 33~40
humidity-sensitive devices were fabricated by a solid reaction method, and their electrical properties were investigated. The specimens exhibited good humidity sensitivity, in which the impedance changes linearly. It is shown that electrical conduction with moisture adsorption is dominated by the ions through characteristics of charging and discharing current, and electrical conductivity increases as rasing the temperature and relative humidity. It is realized that relative permittivity increases and activation energy decreases with increasing relative humidity.
Development of SAW Gas Sensor for Monitoring SOx Gas
Lee, Chan-Woo ; Roh, Yong-Rae ; Chung, Jong-Shik ; Baik, Sung-Gi ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 41~48
We developed SAW gas sensor for monitoring SOx gas with high sensitivity. It was fabricated as a microsensor for detecting SOx gas by depositing sensing material on SAW device. As a detecting layer material, CdS was selected. Deposition of CdS in the form of thin films was carried out by the ultrasonic spray pyrolysis method using ultrasonic spray nozzle. Thin films with the uniform and large surface area for sensors were deposited. The stable pyrolysis environment provided by uniform and fine droplets formed by spray nozzle made it possible to obtain thin films with excellent quality. The minimum grain size of the CdS thin films was about 50 nm when deposited at
. SAW gas sensors showed reasonable sensitivity and reproducibility. Further studies are required to investigate the interference of other gases to SOx gas detection.
Development of coli meter using pressure sensor
Lee, Chan-Won ; Yang, Ki-Sub ; Park, Jong-Sik ; Lee, Jae-Yoon ; Kim, Jae-Chul ; Kwon, Woo-Hyen ; Kim, Sung-Ho ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 49~54
We propose a new method for measuring coliform group in water. In this method we measure the pressure increase rate with time due to the generation of
gas formed during the fermentation of coli. Experimental results by constructed instrument using pressure and temperature sensors show that we can determine the amounts of coli in
hours, which usually takes
hours by conventional methods.
Portable arousal control system using electrodermal activities
Ko, Han-Woo ; Lee, Woan-Kyu ; Kim, Youn-Ho ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 55~64
To control arousal level using physiological index, electrodermal activity signal was detected and separated into skin impedance level and response. Arousal state decision and control algorithm was studied to implement and evaluate real time portable arousal control system. The implemented system can detect and control arousal state from initial drowsy state. This system will be applicable to the evaluation of the effect of warning signal, driver's drowsy detecting system, and sleep study.
Development of Infusion Pump System using Photodiode Array
Kwon, Jang-Woo ; Park, Jung-Sun ; Lee, Dong-Hun ; Lee, Eung-Huyk ; Hong, Seung-Hong ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 65~73
One of the important factor in drug stuffs to a patient is to inject exact amount with stable flow rates. Since improper injection amount and flow rates would cause bad effect to recovery of a patient, the detecting sensors with high sensitivity is required for an injection pump systems' performance improvement. In this study, the three sensors, piezo film sensor, photo transistor and photo array, were compared to find best one for an injection pump monitoring system. Using suggested data processing technique and photo array sensors, we could minimize the effect of interference, disturbance, illumination, and sensitivity change caused by sensor's position. According to the experiments, the photo array showed the higher reliance than any other the three types of sensors.
Development of On-line Water Quality Monitoring System
Kim, Jae-Chul ; Lee, Jae-Yun ; Park, Jong-Sik ; Kwon, Woo-Hyen ; Kim, Sung-Ho ; Lee, Chan-Won ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 75~85
Real time water quality monitoring system in a large area has been developed. The system is hierarchically composed of CCMS(Central Control and Monitoring System), data loggers and water pollution measuring instruments, which enable systematic and efficient data collection and management. Also in this work we designed and constructed the instruments for measuring basic elements in water quality such as salinity, electrical conductivity, temperature, dissolved oxygen and the amount of coli in water.
Characteristics of c-axis oriented PLT thin films and their application to IR sensor
Choi, B.J. ; Park, J.H. ; Kim, Y.J. ; Kim, K.W. ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 87~92
The PLT thin films on (100) cleaved MgO single crystal substrate have been fabricated by rf magnetron sputtering using a PbO-rich target. The dependence of physical and electrical properties on the degree of c-axis orientation has been studied. The degree of c-axis orientation of PLT thin films depends on fabrication conditions. Fabrication conditions of the PLT thin films were such that substrate temperature, working pressure, gas ratio of
, and rf power density were
, 10 mTorr, 10 seem, and
, respectively. In these conditions, the PLT thin film showed the Pb/Ti ratio of 1/2 at the surface, the resistivity of
, and dielectric constant of 110. The pyroelectric infrared sensors with these PLT thin films showed the peak to peak voltage of 450 m V and signal to noise ratio of 7.2.
Fabrication and Electrical Properties of High Tc
Piezoelectric Ceramics Using the Powders Prepared by the Molten Salt Synthesis Method
Park, In-Ho ; Kim, Tae-Gyu ; Nam, Hyo-Duk ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 93~100
ceramics having very high Curie temperatures were synthesized by the conventional oxide mixing method (CON) and the molten salt synthesis method (MSS). Physical characteristics and phase relationship of calcined powders, as well as the sintering behavior, the grain-orientation and dielectric properties of sintered ceramics were investigated as a function of composition and firing temperature. The single
phase was synthesized by using the MSS method at 100 -
lower temperature compared to the CON method. As Nb content increased in
ceramics, the Curie temperature and the dielectric constant at Curie temperature were raised, and the sintering behavior and the degree of grain-orientation were also improved at the same time. The use of MSS-derived powders made it possible to lower the sintering temperature and to improve the dielectric properties of the sintering samples. However, the piezoelectric properties as well as the grain-orientation were not improved any further by the MSS route.
Electrical characteristics of Au and Pt diffused silicon
Chung, Kee-Bock ; Lee, Jae-Gon ; Choi, Sie-Young ;
Journal of Sensor Science and Technology , volume 5, issue 3, 1996, Pages 101~108
junction diodes were fabricated. The fabricated wafers were treated by single or double annealing steps. Single annealing process was performed by diffusion of either Au or Pt into the wafer under the oxygen or nitrogen ambient at
. Second annealing step involved additional annealing of the single annealed wafer under the oxygen ambient at
for one hour. Electrical characteristics of the diodes were investigated to evaluate the effect of the annealing treatments. In the case of single annealing under nitrogen ambient at
for one hour, the amount of leakage current of Pt diffused diode was 75 times larger than that of Au diffused one. The optimum processing condition to achieve high speed silicon
junction diodes from this study was obtained when Pt diffused wafer(treated under the nitrogen ambient at
for one hour) was secondly annealed in an oxygen ambient at
for one hour. The resulting leakage current of two step annealed diodes were remarkably reduced to 1/1100 of the single annealed one. The diode characteristics such as recovery time, breakdown voltage, leakage current, and forward voltage were 4ns, 138V, 1.72nA, and 1V, respectively.