• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.594-597
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• 2023

We have proposed and demonstrated a fiber optic RH (relative humidity) sensor based on fiber Bragg grating covered with a polyimide film. As the polyimide film absolves the moisture in the air, its volume expands. As a result, the grating period of the FBG (fiber Bragg grating) covered with a polyimide film becomes wide and the Bragg wavelength is shifted. The sensor is implemented by fixing a 30 ㎛ thickness polyimide film on the surface of an optical fiber grating using an adhesive, and the characteristics of the device according to humidity are analyzed. The fabricated FBG RH sensor showed a high sensitivity of 0.0186 nm/RH% and a wide measurement range from 30% to 90%. The influence of environmental temperature on the characteristics of the RH sensor was also measured and analyzed. The feasibility of commercialization is presented.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.21-27
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• 2003

The copolymers with various composition of methyl methacrylate (MMA), ethyl methacrylate (EMA), methacrylic acid (MA) and hydroxyethyl methacrylate (HEMA) were synthesized for capacitive humidity sensitive materials. The capacitive humidity sensor consisted of a polymethacrylate film coated on both sides with gold electrode. Capacitance versus relative humidity increased with HEMA content in the copolymer. In the case of self-crosslinkable MMA/MA/HEHA= 40/10/10, the average capacitance at 30%RH, 60%RH and 90%RH are 102, 134 and 166 pF, respectively. And also, the hysteresis, temperature cycle and long-term stability were evaluated as a capacitance humidity sensor.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.199-206
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• 1997

For the Korean Next Generation Reactor(KNGR) development, LBB is considered for the Main Steam Line(MSL) piping inside its containment to achieve cost and safety Improvement. To apply LBB concept to MSL, leak sensors highly sensitive to humidity is required. In this paper, a ceramic material, MgCr$_2$O$_4$-TiO$_2$ has been developed as a humidity sensor for MSL applications. Experiments peformed to characterize the electrical conductivity shows that the conductivity of MgCr$_2$O$_4$-TiO$_2$ responds sensitively to both temperature and humidity changes. At a constant temperature below 10$0^{\circ}C$, the conductivity increases as the relative humidity increases, which makes the sensor favorable for application to the outside of MSL insulation layer But as temperature increases beyond 10$0^{\circ}C$, the sensor composition should be adjusted for the application to KNGR is to be made at temperature above 10$0^{\circ}C$.

• Nuclear Engineering and Technology
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• v.30 no.5
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• pp.435-443
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• 1998

Leak-before-break(LBB) approach has been shown to be both cost effective and risk reductive when applied to high energy Piping in nuclear Power Plants. For the Korean Next Generation Reactor (KNGR) development, LBB application is considered for the Main Steam Line(MSL) piping inside containment. Unlike the primary system leakages, the MSL leak detection systems must be based on principles other than radioactivity measurements. Among humidity, heat and acoustic noise currently being considered as indicators of leakage, we explored humidity as an effective one and developed ceramic-based humidity sensor which can be qualified for LBB applications. The ceramic material, sintered and annealed MgCr$_2$O$_4$-TiO$_2$, is shown to increase its electrical conductivity drastically upon water vapor adsorption over the entire temperature range of interest. With this ceramic sensor specimen, we suggested installation-inside-the-piping method by which we can detect leakage more rapidly and sensitively. In this paper, we describe the progress in the development and characterization of ceramic humidity sensor for the LBB application to the MSL of KNGR.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1728-1731
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• 1996

To develop more sensitive humidity sensor on high temperature region, in this paper, we prepared polyimide humidity sensor by electrophoretic method. Sensing properties of be sensor in high temprature region were studied and compared with that prepared by solution casting method. From the result, the thiner film thickness, the more sensitive. however, It is difficult to make he thickness optimal because of short between electrodes, and the thickness of upper electrode is one of most important parameters affecting pefomance of the sensor.

• Journal of Sensor Science and Technology
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• v.12 no.1
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• pp.24-33
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• 2003

This research is about a comfort sensing system for human environmental monitoring using a one-bodied humidity and temperature sensor and an air flow sensor. The thermal comfort that a human being feels in indoor environment has been known to be influenced mostly by six parameters, i.e. air temperature, radiation, air flow, humidity, activity level and clothing thermal resistance. Considering an environmental monitoring, we have designed and fabricated a one-bodied humidity and temperature sensor and an air flow sensor that detect air relative humidity, temperature and air flow in human environment using surface micromachining technologies. Micro-controller calculates a PMV (predicted mean vote) and CSV (comfort sensing vote) with sensing signals and display a PMV on LCD (liquid crystal display) for human comfort on indoor climate. Our work has demonstrated that a comfort sensing system can provide an effective means of measuring and monitoring the indoor comfort sensing index of a human being. Experimental results with simulated environment clearly suggest that our comfort sensing system can be used in many applications such as air conditioning system, feedback controlling in automobile, home and hospital etc..

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.1014-1016
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• 1998

A capacitance-type humidity sensor using porous silicon layer is developed. The unique property of this sensor is a structure which has electrodes on the surface of the wafer like a general IC device. 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. The measurement of humidity-sensing ability was done for two type of sensors using porous silicon layer formed in 25 and 35% HF solutions, respectively. As the result, the former sensors showed larger value and variation of capacitance for the relative humidity.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.1
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• pp.43-48
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• 2011

In this paper, We have investigated the weak waterproofing defection characteristic of polymer humidity sensor and identified the cause of failure. In high temperature and high humidity conditions(($60^{\circ}C/95%$), the defecting process is simulated about defective and improved samples which are modified for the crosslinking polymer structure's aspect. It is aimed at the defecting reason and suggestion of defection process mechanism.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.849-851
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• 2010

This paper applicate to the large flowers management house, personal office or home, which breed flowers for the profit or hobby. We suggest flower water supply assistant, which supply water anytime to prevent die from water shortage. Our system applicate to the flowerpot less than two at first. We measure humidity by use humidity sensor and control water supply valve automatically. The water supply valve will be opened when the humidity drop to the less than critical values.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.4
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• pp.353-362
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• 2022

In this study, water diffusion in proton exchange membrane fuel cell at open circuit voltage (OCV) was analyzed through experiment. First, the reliability of the micro-sensor (SHT31) was verified. It was concluded the micro-sensor has an excellent reliability at 60℃ and 70℃. After the sensor reliability test, the temperature and relative humidity measurement in bipolar-plate was conducted at OCV. To analyze water distribution and water flux, the temperature and relative humidity was converted into dew point. To the end, it was found water concentration affects water diffusion.