• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.720-724
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• 2008

The purpose of this study is to evaluate the PM10 removal efficiencies of an Air-washer and an Ultrasonic humidifier by mock-up experiments. The concentrations of PM10 were measured at 5 minute intervals using $\beta$-Ray method. The average PM10 removal efficiency of the Air-washer was 79.8%, while the PM10 concentrations increased with the operation of Ultrasonic humidifier. In the case of operating the Air-washer, the R.H(Relative Humidity) level of the test room was maintained at around 45%, regardless of initial R.H condition. The R.H of the test room with Ultrasonic humidifier was influenced by the initial R.H condition.

• Bulletin of the Korean Chemical Society
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• v.20 no.11
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• pp.1277-1280
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• 1999

An inexpensive ultrasonic nebulizer (USN) was developed utilizing a home humidifier. The ultrasonic transducer was taken from a commercial USN and the power supply was from a humidifier. Sample was continuously fed into the nebulizer and the detection limit was improved 3-20 times over a pneumatic nebulizer. Undesirably, noise in signal was also increased several times. 0.5 ppm of Mn was used as an internal reference and the "long-term" drift could be successfully corrected. Since the noise contained high and low frequency components, both could be effectively removed only by the real-time correction method such as the Myer-Tracy method, where the reference line was simultaneously monitored with the analytical lines. The performance of USN was tested with NIST SRMs and showed good agreement with the certified values.

• Journal of Bio-Environment Control
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• v.12 no.1
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• pp.12-16
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• 2003

The effect of humidifying methods on the mean size of droplets ejected from humidifier and distributions of relative humidity in a graft-taking enhancement system (GTES) was investigated. The mean sizes of droplets ejected from an ultrasonic humidifier and a steam humidifier with electrodes were 7.58$\pm$0.14 and 9.01$\pm$0.06 $\mu$m, respectively. Assuming that the particles ejected from humidifiers were mutually combined with distance, the mean diameter of droplets became larger as the distance apart from the outlet of humidifiers increased. When the relative humidity in GRS was controlled at 90％ using the ultrasonic humidifiers, the average relative humidity at the height of 0.4, 1.1 and 1.8 m were 92.1$\pm$5.3, 90.9$\pm$5.6, and 89.7$\pm$6.8%, respectively. However, the average relative humidity using the steam humidifier with electrodes showed 93.4 $\pm$5.4, 90.7$\pm$5.9, and 89.3$\pm$7.0%, respectively. Therefore, it was concluded that humidification by ultrasonic humidifier would be appropriate for the uniform distribution of relative humidity in GTES.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.3
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• pp.227-235
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• 2021

This study examined the effect of ultraviolet (UV) application on bacterial disinfection in a commercialized humidifier using ultrasonic wave (UW). To accurately examine disinfection kinetics in tap-water condition, tap-water was sterilized using a filter, and then inoculated with pure cultures of E. coli and P. putida with known viable counts. The disinfection kinetic characteristics were experimentally compared when UV alone, UW alone, and UW+UV together were applied in disinfecting the added bacteria in the commercialized humidifier. When UV alone was applied, bacterial disinfection kinetics followed a first-order decay reaction, and showed an approximately 10-time weaker disinfection compared to the typical UV disinfection in water treatment or wastewater treatment. When UW alone was applied, bacterial disinfection kinetics followed a second-order decay reaction with a low disinfection rate constant of 0.0002 min^-1(CFU/mL)^-1. When UV and UW were applied together, however and interestingly, the disinfection rate constant (0.0211 min^-1(CFU/mL)^-1) was approximately 100 times increased than that for the UW alone case. These results revealed that the co-use of UV and UW can provide synergistic effect on bacterial disinfection in a tap-water condition in household humidifiers.

• Toxicological Research
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• v.28 no.2
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• pp.103-106
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• 2012

The effect of continuous humidifier use on the bioaerosol concentration in an indoor environment was investigated. An ultrasonic humidifier was operated for 10 hr per day for 15 days in an apartment room. During this time period, viable bioaerosol samples were taken using a single-stage Andersen sampler containing culture media plates for bacteria and fungi. The culture plates were then incubated at room temperature for 2~7 days depending on the media. The counts for the air sample plates were corrected for multiple impactions using the positive hole conversion method and are reported as the colony forming units per cubic meter of air (CFU/$m^3$). While the bacterial concentration measured using the tryptic soy agar (TSA) did not show any significant change during the first 3 days, the concentration increased from the $6^{th}$ day (6979 CFU/$m^3$) and reached a maximum on the $9^{th}$ day (46431 CFU/$m^3$). The concentration then decreased to 2470 CFU/$m^3$ on the $12^{th}$ day, at which point the fungal concentration increased rapidly to 14424~16038 CFU/$m^3$. Also, while the fungal concentration showed a significant change until the $9^{th}$ day of humidifier use, fungal growth was observed on the wallpaper and increased rapidly from the $12^{th}$ day. However, the bacterial concentration increased rapidly after the fungi were removed by remediation. The major fungal species identified in the samples were Penicillium representing 34%, Aspergillus representing 31%, Cladosporium representing 24%, and Alternaria representing 1%. The results also indicated that a relative humidity over 80% was easily achieved with continuous humidifier use. Yet, maintaining a high humidity in a room can cause a rapid outbreak of microbial growth.

• Journal of the Korean Professional Engineers Association
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• v.20 no.3
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• pp.26-29
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• 1987

The physical and chemical characteristics of bacteriostatic water filter media are compared to granular activated carbon upon which a silver impregnated. Silver ion that has been chemically impregnated the activated carbon was the bactericidal agent in water filter media. Also, silver Ion that has teen chemically impregnated onto the activated acetate resin was the bactericidal agent in ultrasonic humidifier. Silver impregnated active carbon and silver cartridge will be able to the bactericidal agents for statical water.

• Mass Spectrometry Letters
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• v.10 no.4
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• pp.103-107
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• 2019

Low-temperature plasma (LTP) ionization is one of the ambient ionization methods typically used in mass spectrometry (MS) for fast screening of chemicals with minimal or no sample preparation. In spite of various advantages of LTP ionization method, including simple instrumentation and in-situ analysis, more general applications of the method are limited due to poor desorption of analytes with low volatilities and low ionization efficiencies in the negative ion mode. In order to overcome these limitations, an ultrasonic vibrator of a commercial hand-held humidifier was interfaced with an LTP ionization source, which generated microdroplets from sample solutions and assisted with LTP ionization. Ionization behaviors of various chemicals in microdroplet-assisted LTP (MA LTP) were tested and compared with typical LTP ionization from dried samples applied on a surface. MA LTP efficiently ionized small organic, amino, and fatty acids with low volatilities and high polarities, which were hardly ionized using the standard LTP method. Facile interaction of LTP with ultrafine droplets generated by ultrasonic resonator allows efficient ionization of relatively non-volatile and polar analytes both in the positive and negative ion modes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1017-1026
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• 2016

The present paper describes the two off-surface visualization techniques and their application examples to vortex flows. One of the two visualization techniques is the classical smoke-wire technique, and the other is the visualization technique using the micro water-droplets generated by the home-style ultrasonic humidifier. The smoke-wire technique has the limit of air flow speed (about 5 m/sec for 0.07 mm-diameter wire) and the pollution problem, but it produces very fine and clear streak line sheet. It is applied to visualize the wing-tip vortices of a 3-dimensional wing. The micro water-droplet technique has the larger limit of air flow speed (above 10 m/sec) and is free from pollution and toxic problems compared to the smoke-wire technique. It is successfully applied to visualize the complex vortex system of a double-delta wing with an apex strake.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.388-393
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• 2001

An experimental study is conducted to investigate the interaction of vortices over a delta wing with leading edge extension(LEX) through the off-surface flow visualization and the 5-hole probe measurements of the wing wake region. Especially, the application of a new visualization technique is employed by ultrasonic humidifier water droplet and laser beam sheet. The results, both the off-surface visualization and the 5-hole probe, show that LEX tends to stabilize the vortices of the delta wing up to the high angle of attack even though the model is yawed. With increasing yaw, the windward leading edge vortex moves inward, and closer to the wing surface, while the leeward vortex moves outwards and away from the wing surface. The vortex interaction is promoted in the windward side, and is delayed in the leeward side.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.1
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• pp.63-74
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• 2003

The vortical flow of a 65-deg flat plate delta wing with a leading edge extension(LEX) was examined through off-surface visualization, 5-hole probe and hot-film measurements. The off-surface flow visualization technique used micro water droplets generated by a home-style ultrasonic humidifier and a laser beam sheet. The angles of attack ranged from 10 to 30 degrees, and the sideslip angles ranged from 0 to -15 degrees. The Reynolds number was $1.82{\times}10^5$ for the flow visualization, and $1.76{\times}10^6$ for the 5-hole probe and hot-film measurements. The comparison of the visualization photos and the flow field measurement showed that the two results were in a good agreement for the relative position and the structure of the wing and LEX vortices, even though the flow Reynolds numbers of the two results were much different. The wing vortex and the LEX vortex coil each other while maintaining a comparable strength and identity at zero sideslip. Neither a looping of the wing vortex around the strake vortex, nor the lopsided coiling of the stronger strake and the weaker wing vortices was observed. At non-zero sideslip, the downward movement of the LEX vortex when going downstream was enhanced on the windward side, and the downward and inboard movement of the LEX vortex when going downstream was suppressed on the leeward side. The counterclockwise coiling of the wing and LEX vortices was decreased significantly on the leeward side.