• Fire Science and Engineering
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• v.16 no.4
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• pp.15-19
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• 2002

This dissertation is about the development of $BaTiO_3$-type PTC(Positive Temperature Coefficient) thermistor by composition method. A multilayer-type PTC samples were fabricated under optimal conditions after setting the experimental composition equation as ($Ba_{0.95-x}$S $r_{0.05}$$Ca_{x}$ )$TiO_3$-$0.01TiO_2$-$0.01SiO_2$-$\alpha$$MnCO_3$-$\beta$N $b_2$ $O_{5}$.) and their testing results were analyzed. The optimal sin-tering and cooling temperatures were 13$50^{\circ}C$ for two hours and $100^{\circ}C$/h for an hour, respectively; By composing Ca and Mn, dopants to lower the resistivity at room temperature, and Nb, a dopant to raise peak resistivity(Ca:5 mol%, Mn:0.08 mol%, Nb:0.18 mol%), appropriately, a PTC thermistor, having the characteristics of relatively low resistivity at room temperature and high peak resistivity and a good temperature coefficient, has been developed. And we find that it is possible of application for fire detection sensor.r.r.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.115-120
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• 2008

The thermistors and AD590 are widely used for temperature measurement in space application. The resistance of thermistor will vary according to the temperature variation therefore the external voltage or current stimulus signal have to be provided to measure resistance variation. Recently high resolution electro optic camera system of satellite requires tight thermal control of the camera structure to minimize the thermal structural distortion which can affects the image quality. In order to achieve $1^{\circ}$(deg C) thermal control requirement, the accuracy of temperature measurement have to be higher than $0.3^{\circ}$(deg C). In this paper, the accuracy of temperature measurement using thermistors is estimated and analyzed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.788-795
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• 2000

In this paper, a method for the precise impedance measurement of coaxial loads using an offset open and short as the reflection standards and reference air lines with different lengths as the impedance standards is proposed. Measured input impedances of power sensors and thermistor mounts obtained from SWR bridges(5~400MHz) and a vector network analyzer(100~1,000MHz) are presented in the frequency range of 5MHz to 1,000 MHz.

• Journal of Sensor Science and Technology
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• v.25 no.1
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• pp.35-40
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• 2016

Pulse diagnosis is one of the representative diagnostic methods in Oriental medicine. In this study, a pulse pressure sensor array coated with silicone, which includes 6 piezo-resistive sensors and 1 thermistor, is fabricated for pulse measurement. It is necessary to coat the pulse sensor array with silicone to avoid the fracture or damage of pressure sensors when the sensor is in contact with the skin and a constant pressure is applied. However, the silicone coating on the pulse sensor array can cause signal interference among the sensors in the pulse sensor array. The interference number (IN), a calculation for expressing the degree of interference among channels, is changed according to the silicone thickness on the pulse sensor array. The IN is increased by a thick silicone coating, but the fabrication error, an important index for the mass production of the sensor array, is reduced by the thickness of the silicone coating. We propose that the thickness of the silicone on the pulse sensor array is an important consideration for the performance of the fabricated sensor and manufacturing repeatability.

• Journal of Biosystems Engineering
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• v.16 no.4
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• pp.363-371
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• 1991

It is important to measure the somatic informations for stockbreeding automatization. This study was carried out for the development of wireless measurement system of temperature in living animals. New method to measure somatic temperature was developed using the single-channel wireless instrument. This system was constructed by oscillator, temperature sensor, wireless transmitter and receiver circuit, single processing circuit, and microcomputer. Two types of sensor were used and compared to measure the temperature. The thermistor sensor was more sensitive and accurate than platinum resistance sensor, however both sensors were performed efficiently. The single-channel wireless measurement systems developed could measure the somatic temperature successfully and offered a versatile system.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.391-396
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• 2001

In order to estimate thermal cracking in mass concrete and to decide the removal time of the forms outside the concrete structures in wintertime, temperature measurement is indispensible. Until now, the measurement system employs thermocouple type. In this paper, we introduce economical and accurate NTC(Negative Temperature Coefficient) ceramic type measurement system. In principle, NTC ceramic type sensor is very sensitive in the range -20~15$0^{\circ}C$. In this range, the signal change is so large that the sensor needs less amplification than thermocouple. Therefore, not only the sensor itself is inexpensive but also the system is too. In this experiments the temperature of the NTC system are identical to those of thermocouple. In conclusion, inexpensive NTC thermistor system is very adequate to the temperature measurement during concrete curing.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.376-378
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• 1995

A method is presented for the design and fabrication of the temperature compensation circuits on the Clark electrodes for measuring the dissolved oxygen(DO) concentration. The discussion includes a method of the sensor interface circuits for the DO sensor. Typical polarograms for the DO probes under test using this sensor circuits are presented. High accuracy over 99 % of the I to V conversion using the proposed circuit is verified. Temperature dependence for the test DO probe is well compensated automatically using the thermistor($2k\Omega,\;25^{\circ}C$) in series with correction resistor in the feedback loop of the op-amp circuit in the temperature range of the 0-50$^{\circ}C$.

• Journal of the Korea Computer Industry Society
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• v.10 no.5
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• pp.193-200
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• 2009

In this paper, the raid and fire preventable system using Zibee module with IEEE 802.15.4 wireless communication standard and multi-sensor was developed displaying raid and firing condition with wireless network. The raid preventable system is designed using a ultrasonhe waves sensor and infrared sensor. The fire preventable system is designed using a thermistor. The datas for raid and firing condition are communicated from enddevice to coordinator with wireless network and are displayed on PC monitor.

• Journal of the Korean Solar Energy Society
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• v.28 no.6
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• pp.58-63
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• 2008

It is essential to investigate the structure and the main characteristic of Home USN (Ubiquitous Sensor Network) technologies in built ubiquitous environment while designing bio-sensors. For this study, Thermistor elements and Thermopile black body have been selected to implement ubiquitous technologies for bio-sensors and wireless network such as WiBro has been used to transfer sensing data to the BSN (Bio-Sensor Network) gateway. It is certain that efficiency of ubiquitous space design is improved if main components of each specific sensor network are analyzed precisely in digital way and corresponding communication modules are prepared accordingly. Ubiquitous technology, in conclusion, has to be applied not only with systematical mechanism or electronic setting but in human-centered atmosphere as well, keeping with deep consideration for bio-housing service factors in eco-friendly surrounding.

• Journal of Sensor Science and Technology
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• v.1 no.1
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• pp.67-75
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• 1992

PTC thermistor has been fabricated with as-received $BaTiO_{3}$ powder and its electrical properties were investigated. The resistivity of the PTC thermistor was measured at $20^{\circ}C$ intervals from $20^{\circ}C$ to $200^{\circ}C$. The electrical characteristics of the PTC thermistor are determined by the ac complex impedance analysis. The average grain size measured with a scanning electron microscope increased from $3.8{\mu}m$ to $8.8{\mu}m$ with increasing sintering temperature between $1280^{\circ}C$ and $1400^{\circ}C$. The maximum resistivity jump was $4{\times}10^{5}$. The bulk resistivity of the thermistor sintered above $1340^{\circ}C$ decreased with increasing temperature of the measurement. The grain boundary resistance increased exponentially, the grain boundary capacitance decreased, and the built-in potential at the grain boundary increased with increasing temperature of the measurement. The charge densiy at the grain boundary increased with increasing temperature up to $110^{\circ}C$, which leveled off with further increase in measuring temperature.