• Journal of the Semiconductor & Display Technology
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• v.6 no.4
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• pp.43-47
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• 2007

In this paper, we propose a novel sensor system for measuring the arterial pulse in an oral cavity. In order to measure pulse wave in oral cavity, the proposed system is designed with reflection type arterial wave sensor, not by using transmission type arterial pulse wave sensor. Driving circuit through pulse current is designed for solving self-heating problem of LED. The effectiveness of the proposed sensor system is compared with pulse wave between pulse wave of oral cavity and other body parts as well as with characteristic measurements. The experiment shows that the proposed sensor system is adaptive to capturing consecutive and meaningful biometric signals through the variation of pulse wave changes in oral cavity when exercising. The study result expects to design and develop mobile sensors which could be adapted to healthcare devices.

• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.261-266
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• 2008

In this paper, we present thermal characteristics of high-temperature measurement sensor using fiber Bragg grating(FBG), including peak reflectivity, FWHM bandwidth and various normalized refractive index change along temperature variation. The temperature stability of FBG temperature sensor can be changed by varying the refractive index change and grating length. The proposed FBG temperature sensor can measure up to about $600^{\circ}C$ and 1000 hours of heating time.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.5
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• pp.510-517
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• 2004

A fine hot-wire is used both as a heating element and a temperature sensor in transient hot-wire method. The traditional sensor system is unnecessarily big so that it takes large fluid volume to measure the thermal conductivity. To dramatically reduce this fluid volume, a new sensor fabrication and a data processing method are proposed in this article. Contrast to the conventional and most popular two wire sensor, the new sensor system is made up of divided multiple long and short wires. Through validation experiments, it is found that the measured thermal conductivities of the glycerin are exactly same each other between the conventional and proposed new method. Also some technical considerations in arranging the multiple wires are briefly discussed.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.210-215
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• 2003

A fine hot-wire is used both as a heating element and a temperature sensor in transient hot-wire method. The traditional sensor system is unnecessarily big so that it takes large fluid volume to measure the thermal conductivity. To dramatically reduce this fluid volume, a new sensor fabrication and a data processing method are proposed in this article. Contrast to the conventional and most popular two wire sensor, the new sensor system is made up of divided multiple long and short wires. Through validation experiments, it is found that the measured thermal conductivities of the glycerin are exactly same each other between the conventional and proposed new method. Also some technical considerations in arranging the multiple wires are briefly discussed.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.16 no.4
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• pp.254-261
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• 2016

The present research paper is devoted to solving an urgent problem, i.e., the energy saving and energy efficiency of buildings. A rapid settlement method and experimental control of the energy conservation based on the specific characteristics of the thermal energy consumption for the heating and ventilation of the buildings, and as well as the rapid development of wireless sensor networks, can be used in a variety of monitoring parameters in our daily lives. Today's world has become quite advanced with smart appliances and devices such as laptops, tablets, TVs, and smartphones with various functions, and their use has increased significantly in our day-to-day lives. In this case, the most important role is played by a wireless sensor network with its development and use in heterogeneous areas and in several different contexts. The fields of home automation, process management, and health management systems make extensive use of wireless sensor networks. In this paper, we explore the main factors of the microclimate in an indoor environment. We control the temperature humidity, and other factors remotely using sensors and Internet-of-Things technologies.

• Journal of Sensor Science and Technology
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• v.3 no.1
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• pp.12-18
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• 1994

In this study, we fabricated and characterized a calorimetric-type flow sensing element using a micromachined silicon substrate. The cooling and heating effects resulted from the gas flow were measured by two temperature sensors located at both sides of the heating resistor, and the insulator diaphragm was employed as a substrate in order to improve thermal isolation. The sensor generated $0{\sim}378.4mV$ output signal under 10V bridge-applied voltage when the nitrogen gas was passed on the sensor surface having a mass flow rate of $0{\sim}0.25grs/min$, and reached to the stable operating condition within 10 seconds.

• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.369-375
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• 2021

In this study, heterogeneous ZnO/CNTF composites were developed to improve the NO₂-sensing response, facilitated by the self-heating property. Highly conductive and mechanically stable CNTFs were prepared by a wet-spinning process assisted by the liquid crystal (LC) behavior of CNTs. Metal-organic frameworks (MOFs) of ZIF-8 were precipitated on the surface of the CNTF (ZIF-8/CNTF) via one-pot synthesis in solution. The subsequent calcination process resulted in the formation of the ZnO/CNTF composites. The calcination temperatures were controlled at 400, 500, and 600 ℃ in an N₂ atmosphere to confirm the evolution of the microstructures and NO₂-sensing properties. Gas sensor characterization was performed at 100 ℃ by applying a DC voltage to induce Joule heating through the CNTF. The results revealed that the ZnO/CNTF composite after calcination at 500 ℃ (ZnO/CNTF-500) exhibited an improved response (R_air/R_gas = 1.086) toward 20 ppm NO₂ as compared to the pristine CNTF (R_air/R_gas = 1.063). Selective NO₂-sensing properties were demonstrated with negligible responses toward interfering gas species such as H₂S, NH₃, CO, and toluene. Our approach for the synthesis of MOF-driven ZnO/CNTF composites can provide a new strategy for the fabrication of wearable gas sensors integrated with textile materials.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.6
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• pp.539-546
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• 2006

The Air Quality Sensor(AQS), located near the fresh air inlet, serves to reduce the amount of pollution entering the vehicle cabin through the HVAC(heating, ventilating, and air conditioning) system by sending a signal to close the fresh air inlet door/ventilation flap when the vehicle enters a high pollution area. The sensor module which includes two independent sensing elements for responding to diesel and gasoline exhaust gases, and temperature sensor and humidity sensor was designed for intelligent AQS in automobile. With this sensor module, AVR microcontroller was designed with back propagation neural network to a powerful gas/vapor pattern recognition when the motor vehicles pass a pollution area. Momentum back propagation algorithm was used in this study instead of normal backpropagation to reduce the teaming time of neural network. The signal from neural network was modified to control the inlet of automobile and display the result or alarm the situation in this study. One chip microcontroller, ATmega 128L(ATmega Ltd., USA) was used for the control and display. And our developed system can intelligently reduce the malfunction of AQS from the dampness of air or dense fog with the backpropagation neural network and the input sensor module with four sensing elements such as reducing gas sensing element, oxidizing gas sensing element, temperature sensing element and humidity sensing element.

• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.292-297
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• 2004

Carbon nanotubes (CNT) were synthesized by arc-discharge method. To fabricate CNT sensor, CNT powder was dispersed in ${\alpha}$-Terpinol($C_{10}H_{17}OH$) solution. The CNT tilms were fabricated by screen printing method on the interdigitated Pt/Pd alloy electrode. The microstructure of CNT film was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In order to investigate the gas sensing characteristics of the film, the CNT film was experimented to measure NO response and recovery time. The CNT sensor with a heater was compared to that without a heater. And this sensor shows better reproductibility and faster recovery time than another CNT sensors. We suggest the possibility to utilize a CNT as new sensing materials for environmental monitoring.

• Journal of Sensor Science and Technology
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• v.20 no.6
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• pp.363-367
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• 2011

This paper proposes a highly-sensitive gas flow sensor with a simple structure. The sensor is composed of a micro-heater for heating the gas medium and a pair of temperature sensors for detecting temperature differences due to gas flow in a sealed chamber on one axis. Operation of the gas flow sensor depends on the transfer of heat through the air medium. The proposed gas flow sensor has the capability to measure gas flow rates <5 $cm^3$/min with a resolution of approximately 0.01 $cm^3$/min. Furthermore, this paper reports some additional experiment results, including the sensitivity of the proposed gas flow sensor as a function of operating current and the flow of different types of gas(oxygen, carbon dioxide, and nitrogen). The fabrication process of the proposed sensor is very simple, making it a good candidate for mass production.