• Journal of Mechanical Science and Technology
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• v.19 no.4
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• pp.1018-1026
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• 2005

The proton exchange membrane (PEM) fuel cell system consisting of stack and balance of plant (BOP) was modeled in a MATLAB/Simulink environment. High-pressure operating (compressor type) and low-pressure operating (air blower type) fuel cell systems were con­sidered. The effects of two main operating parameters (humidity and the pressure of the supplied gas) on the power distribution characteristics of BOP and the net system efficiency of the two systems mentioned above were compared and discussed. The simulation determines an optimum condition regarding parameters such as the cathode air pressure and the relative humidity for maximum net system efficiency for the operating fuel cell systems. This study contributes to get a basic insight into the fuel cell stack and BOP component sizing. Further research using muli­object variable optimization packages and the approach developed by this study can effectively contribute to an operating strategy for the practical use of fuel cell systems for vehicles.

• Journal of Applied Reliability
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• v.13 no.2
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• pp.109-116
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• 2013

The solder is any of various fusible alloys, usually tin and lead, used to join metallic parts that provide the contact between the chip package and the printed circuit board. Solder plays an important role of electrical signals to communicate between the two components. In this study, two kinds of Ag-free solder as sample is made to conduct the thermal shock test and the high humidity temperature test. Low resistance is measured to estimate crack size of solder, using daisy chain. The low speed shear test is also performed to analyze strength of solder. The appropriate degradation model is estimated using the result data. Depending on the composition of solder, lifetime estimation is conducted by adopted degradation model. The lifetime estimated two kinds of Ag-free solder is compared with expected lifetime of Sn-Ag-Cu solder. The result is that both Ag-free composition are more reliable than Sn-Ag-Cu solder.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.626-629
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• 2021

Recent home appliances requires convenience and low-power consumption. A convenient devices should be simple to control while having several functions. Intelligent sensors and utilization technologies are required to reduce energy consumption. This paper provides a smart drying system with Bluetooth communication function and energy reduction function. Design a control system that uses the Bluetooth function so that the smartphone monitors the drying control and the internal humidity condition. By detecting the humidity inside the dryer and controlling the speed of the motor, it has an energy-saving function.

• Journal of Bio-Environment Control
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• v.22 no.2
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• pp.146-153
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• 2013

This study was conducted to enhance graft-take ratio and quality of grafted tomato seedlings by controlling temperature and humidity during the healing and acclimatization processes. Three temperature levels ($20^{\circ}C$, $23^{\circ}C$, and $26^{\circ}C$) were carried out to determine optimum temperature on four rootstocks. In addition, twelve combinations of three relative humidity levels (70%, 80%, and 90%) and four temperature levels ($17^{\circ}C$, $20^{\circ}C$, $23^{\circ}C$, and $26^{\circ}C$) were set up to evaluate the effect of relative humidity and temperature on the graft-take ratio of grafted seedlings. In the other hand, five relative humidity periods (H0, H1, H2, H3, and H4: 90% relative humidity for first 0, 1, 2, 3 and 10 days and afterwards relative humidity was reduced to 70%, respectively) were examined effect of relative humidity periods on the graft-take and quality of grafted seedlings. The higher graft-take ratios (84.0~87.4%) were showed at $23^{\circ}C$ compared to $20^{\circ}C$ and $26^{\circ}C$ in all rootstocks. Graft-take ratios decreased and number of diseased plants increased at high temperature. The graft-take ratios increased with increasing relative humidity in all temperature levels on the $3^{rd}$ and $7^{th}$ day after grafting. However, increasing relative humidity significantly increased percent of diseased plants. The graft-take ratio reduced at ($26^{\circ}C$) and ($17^{\circ}C$) temperature under all relative humidity conditions. The graft-take ratio increased with increasing period of 90% relative humidity. Maximum graft-take ratios were observed in H2 and H3 treatments. Graft-take ratio decreased with increasing 90% relative humidity for 10 days (H4). Diseased plants had not been found in H0, H1, H2, and H3 treatments. Seedling quality was improved through increasing fresh and dry weight of root, compactness, and root morphology of tomato seedlings in H2 and H3 treatments. Therefore, high relative humidity (90%) for first 2 or 3 days and afterwards reduced low relative humidity (70%) at $23^{\circ}C$ condition during healing and acclimatization promoted the graft-take and quality of grafted tomato seedlings.

• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.32-37
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• 1999

A capacitance-type humidity sensor with mesa structure in which porous silicon layer is used as humidity-sensing material is developed and its humidity sensing properties are measured. This sensor has a structure where two electrodes are set on the up-side of the wafer against the past typical structure having these electrodes on the up and down-side of the wafer. Therefore, the sensor can be fabricated monolithically to be more compatible with the IC process technology, and is possible to detect more correct output capacitance by removing the effect of the parasitic capacitance from the bottom layer and other junctions. 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. From the completed samples, the dependence of capacitance on the relative humidity of 55 to 90% more was measured at room temperature. As the result, the measured capacitance increased monotonously higher at the low frequency of 120 Hz, where the capacitance was observed to increase over 300%.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.4
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• pp.420-425
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• 1986

This study was conducted to investigate the influence of air temperature and relative humidity on excessive drying rate of burley tobacco. In experiment I, 4 temperatures and I humidity by day and air curing by night were treated from initial curing stage. In experiment II, 15 combinations of 3 temperatures and 5 humidities were applied from the yellow stage of cure. Yellowish cured leaves resulted from overdrying at high temperature and especially, at low humidity. How- ever, these were not produced at 75-80% RH and under 35$^{\circ}C$ by day with air curing b y night. The proper range of temperature and humidity for desirable color of cured leaf were the combinations of 30$^{\circ}C$, 75-80% RH or 35$^{\circ}C$, 80-85% RH. As excessive drying leaves increased, physical properties of cured leaves were poorer and chemical contents were less decomposed.

• Current Research on Agriculture and Life Sciences
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• v.3
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• pp.99-104
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• 1985

This research was carried out study the effect of several relative humidities on the cracking of kernels of chestnuts. The moisture contents of total kernel increased at the higher humidity over 88% relative humidity. but the moisture contents of inner layer was decreased at low relative humidity below 76 %. The starch contents of kernel decreased, but free stgars increased during the total period of storage. The tannin contents increased during total of storage, and the tannin contents of out layer was higher than inner layer because of tannin transfer from astringent shell. As we considered the sprouting ratio, the rotting ratio and the cracking ratio, the optimal relative humidity of chestnut storage was proved 88% relative humidity.

• Applied Biological Chemistry
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• v.23 no.1
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• pp.1-6
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• 1980

The sorption characteristics of red pepper powder were analyzed in respect to its storing humidities and the types of powder product. The sorption rate of the powder was affected by the humidity values under which it was stored. At low relative humidity values below 70% RH the sorption equilibrium was easily attained, but at the higher humidity over 75% RH the equilibrium state was not reached even after a long period of storage. From the estimation of the sorption rate at arbitrary humidity an empirical equation was obtained; In ${\frac{dw}{dt}}=n\;ln(t)+ln\;c$, where w is moisture content(%) absorbed, t is time (hour) and n and c are empirical constants which were determined from empirical data. Particle sizes and drying methods of red pepper showed little effect on the sorption behavior.

• Journal of Conservation Science
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• v.36 no.4
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• pp.255-263
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• 2020

Paulownia coreana has various advantages as a convenient workability, aesthetic outlook, beautiful patterns, low weight and high strength, and its permeability. P. coreana has been widely used for storage but there are no empirical researches proving its functionality in a field of conservation science until now. In this study, the seasonal and daily temperature and relative humidity control, and microbe and insect repellent activity were evaluated under the controlled and uncontrolled circumstances from 2015 to 2016. The results showed to be mainly excellent in relative humidity control and the buffering effect was good to adjust the average daily relative humidity range from the outside. With respect to the antimicrobial properties of P. coreana, we observed that its water-soluble extract produced visible zones of inhibition against five bacteria. However, it was difficult to predict the antimicrobial and/or insecticidal properties.

• Fashion & Textile Research Journal
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• v.2 no.5
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• pp.416-422
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• 2000

In this study, to find out the physiological reaction of the human body and the sensation of comfort when people are wearing sportswear which is made of waterproof breathable fabrics under general environmental conditions (temperature : $20{\pm}1^{\circ}C$, humidity : $60{\pm}5%RH$, air current : 0.1 m/sec) and rainy environmental conditions (temperature : $20{\pm}1^{\circ}C$, humidity : $60{\pm}5%RH$, air current : 0.1 m/sec, rainfall : 250 1/hr), we made an experiment with sportswear in an artificial climate chamber and studied the thermal physiological response and subjective sensation. Mean skin temperature of the subjects was low and had a big range of fluctuation in rainy environmental conditions of two condition. Temperature started to increase at the beginning of the exercise, reached the maximum at the 2nd level of the exercise and then started to decline. Rectal temperature showed a slighter increase and bigger range of fluctuation in general conditions than in rainy conditions. Except clothing micro climate in rainy conditions, temperature and humidity and their range of fluctuation around back were higher than those around chest. Humidity was high and had wide range of fluctuation in general conditions. Heart rate was 4.4 beats/min higher in general conditions. In subjective test on rainy conditions, the feeling of discomfort increased due to the raindrops fallen on the skin. Unlike that in general conditions, cold sensation increased and humidity sensation reached to the peak after the exercise. In wearing sportswear made of shape memory breathable waterproof fabric, controlling function over a small amount of heat and water was distinctive while it turned out to be not so comfortable over a large amount of heat and water. Through this, the limitation of shape memory breathable waterproof fabric was recognised.