• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1689-1696
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• 2020

In this study, we developed a fiber-optic humidity sensor (FOHS) system for the monitoring and detection of coolant leakage in nuclear power plants. The FOHS system includes an FOHS, a spectrometer, a halogen white-light source, and a Y-coupler. The FOHS is composed of a humidity-sensing material, a metal tube, a multi-mode plastic optical fiber, and a subminiature version A (SMA) fiber-optic connector. The humidity-sensing material is synthesized from a mixture of polyvinylidene fluoride (PVDF) in dimethyl sulfoxide (DMSO) and hydroxyethyl cellulose (HEC) in distilled water. We measured the optical intensity of the light signals reflected from the FOHS placed inside the humidity chamber with relative humidity (RH) variation from 40 to 95%. We found that the optical intensity of the sensing probe increased linearly with the RH. The reversibility and reproducibility of the FOHS were also evaluated.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.3
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• pp.143-148
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• 2018

In this study the performance and humidity variation for 2 unit cells connected in series were experimentally measured. The relative flow direction of hydrogen and air was changed from parallel flow to counter flow. Internal humidity distribution was then measured by 5 embedded sensors on each channel. In all experimental conditions, the former unit cell showed a better performance and the gap is noted to be higher when counter flow is applied. The performance was noted to be higher at high humidification case in the parallel flow. However, in the counter flow, the difference of performance according to the humidification is negligible. Hydrogen and air are discharged from the PEMFC unsaturated with water vapor at parallel flow/low humidification condition, which explains lower performance of the PEMFC than other conditions. The humidities in hydrogen and air streams of counter flow were noted to increase rapidly even at low humidification condition and the consequential even hydration of membrane is the reason of higher performance.

• The Korean Journal of Zoology
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• v.8 no.2
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• pp.51-54
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• 1965

Present author observed the variation in color and pattern and also those of geographical distribution of Graphosoma rubrolineatum WESTWOOD.And the variations were also studied in relation to the temperature and the humidity . The results are as follows . 1. The variations in color and pattern of G.rubrolineatum were gradually changed into black ones, and so they showed polymorphic. 2. Their colors and patterns were not variated in inland at all, while those variations in island increased according to the distance from the inland. 3. The red color of the patterns appeared the yellowish-red in inland, the blackish -red in island. 4. The variation in color and pattern of G.rubrolineatum occure in the region of the temperature below 22.8$^{\circ}C$ (mean temperaturrre of June, July and August)and the humidity above 72%(yearly average).

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2828-2833
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• 2008

Water management is one of many operating parameters, which influences the performance and stability of a proton exchange membrane fuel cell (PEMFC). Local humidity condition including liquid water saturation has profound impacts on the distributions of overpotentials, current density, and membrane water content. Computational fluid dynamics simulations were conducted to investigate the effect of the inlet humidity variation on the performance of a PEMFC of $9\;cm^2$ active cell area with serpentine flow fields. The results showed that the performance of the simulated PEMFC remained at an almost same level when the cathode inlet humidity was changed from 100% to 60%, while reaching its maximum at air humidity of 80%. However, further decrease in the cathode inlet humidity below 40% started to significantly deteriorate the performance of the PEMFC. The variations of overpotentials, membrane water content, etc. due to the change in the cathode inlet humidity were also discussed.

• International Journal of Air-Conditioning and Refrigeration
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• v.9 no.1
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• pp.65-70
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• 2001

During the summer season, it is very hot and humid in Korea. So the humidity is an important factor regarding the environmental control function of building envelops. The purpose of this research is to measure and analyze the characteristics of such environmental factors as relative humidity, dry bulb temperature and air velocity varies both in the clay and cement envelop structures using granite dome models during the summer time. The interior relative humidity of the clay model is constant regardless of exterior humidity although a little range of variation is shown in comparison to the cement model.

• International Journal of Air-Conditioning and Refrigeration
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• v.9 no.1
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• pp.71-76
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• 2001

Factors governing the rate of heat exchange comprise temperature, air velocity, relative humidity, and relation indoors. Recently, there are many researches on the transient analysis of indoor environmental factors such as dry bulb temperature, relative humidity and air velocity in miniature models. The purpose of this study is to measure the environmental factors and to analyze and evaluate the characteristics of indoor environment in different envelop structures using granite dome models. The interior relative humidity is constant regardless of exterior humidity although a little range of variation is shown in comparison to the cement model.

• Journal of Sensor Science and Technology
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• v.1 no.2
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• pp.125-130
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• 1992

A resistive-type humidity sensors have been fabricated using cross-linked PMMA thin film as sensing material and their humidity characteristics have been investigated. The sensor coated of the cross-linked PMMA with PVA exhibited largely variation of resistance by increase of relative humidity and less than 3% of hysteresis. Furthermore, the fabricated sensor exhibited superior long-term stability. The response time of the PMMA humidity sensor was about 7 min. for adsorption and about 5 min. for desorption respectively.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1002-1007
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• 2008

The floor structure of railway vehicle can deflect and warp due to variation of temperature and humidity at the inside and outside of vehicle. In this study, its temperature and humidity characteristics was investigated experimentally for beam and plate specimen and numerically for the floor structure assembly. The temperature and humidity characteristics of a part were measured and the deformation and stress distribution of the floor structure were calculated using a commercial software. And the warp deformation of the plywood was measured experimentally. The results show that the temperature and humidity effects on the floor structure are the important factor to decide the strength and the quality of the floor structure of railway vehicles.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.322-327
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• 2007

Dedicated outdoor air-conditioning(DOA) system that utilizes pre-cooling and desiccant dehumidification can be superior to conventional cooling and reheating system with respect to energy consumption and indoor thermal comfort. In this work, simulation has been conducted to study various factors that affect the performance of DOA. Dynamic simulation shows the transient variation of temperature and humidity as the on/off control logic is imposed. Exit humidity of process air and flow rate are varied to study the effect on exit temperature of process air, dehumidification quantity, required regeneration temperature and exit humidity of regeneration air. For an outdoor air condition of $28.5^{\circ}C$ temperature, 16 g/kg humidity ratio and 2000 cmh flow rate, the dehumidification efficiency is increased by 4.6% as the flow rate is doubled.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.4
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• pp.294-299
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• 2000

For practical application as a humidity sensor SnO$_2$thick films devices were fabricated on the refresh type electrode by screen printing method and their material and humidity sensing properties were investigated. As a function of Sb$_{2}$/O$_{3}$ addition rate grain size was increased while porosity and initial resistance were rapidly decreased. And the area of resistance variation according to relative humidity was decreased with increasing heat treatment temperature. SnO$_2$thick film device heat treated at 95$0^{\circ}C$ and contained 0.05mole% Sb$_{2}$/O$_{3}$ had a best humidity sensing properties. From this result it is conformed that humidity sensing properties of SnO$_2$thick film devices could be approved by very small amount of Sb$_{2}$/O$_{3}$ addition.