• Journal of the Korean Society of Safety
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• v.22 no.1 s.79
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• pp.24-29
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• 2007

The effectiveness of a UV(ultra violet) disinfection system depends on the characteristics of the waste water, flow conditions, the intensity of UV radiation, the amount of time the microorganisms are exposed to the radiation, and the reactor configuration. The wast water flow conditions are important factors in the design of UV disinfection system from the point of enhancement view of UV disinfection. The turbulent energy intensity in the wake by the vortex shedding are effective for UV radiation. Therewith the effectiveness of vortex generator is considered as a enhancement of UV disinfection. The experimental results presented give important evidences and explain that it is possible to predict UV disinfection performance based on flow experiments. An experimental investigation of two types of the vortex generator is presented. The qualitative and quantitative evaluations of the wake are made by flow visualization using smoke wire method and the measurement of vortex frequencies in the wind tunnel. From the experiment, following results were obtained that the delta wing type vortex generator is more effective than circular type because of the higher vortex frequencies and the smaller drag.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.94-100
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• 2024

Recently, as interest in personal hygiene has increased due to the community spread of COVID-19 and variant viruses, fixed and potable UV germicidal equipment to sterilize indoor spaces and hand-held UV germicidal equipment to sterilize household items such as masks and mobile phones are continuously being developed and sold. However, the development and sales of the product are difficult because appropriate testing methods have not yet been established. In this situation, if an uncertified product is distributed in the market, it can cause serious harm to consumers. In this study, we investigate the photobiological risks and safety devices against UV exposure of UV germicidal equipment distributed domestically, and propose appropriate test methods for portable UV germicidal equipment based on the research results.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.3
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• pp.402-407
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• 2012

The effects of a combined treatment of aqueous chlorine dioxide ($ClO_2$) and ultraviolet-C (UV-C) irradiation on microbial growth in celery and cherries were investigated. Celery and cherry samples were treated with 50 ppm $ClO_2$, UV-C at dose of 10 kJ/$m^2$, and a combination of $ClO_2$ and UV-C. The changes in the counts of Escherichia coli O157:H7 inoculated in the celery and cherries as well as those of total aerobic bacteria, yeast and molds in the celery and cherries were investigated after each treatment. After the combined treatment of aqueous $ClO_2$ and UV-C irradiation, the populations of E. coli O157:H7 in the inoculated celery and cherries were reduced by 2.8 and 3.0 log CFU/g, respectively, compared to those of the control. For the un-inoculated celery and cherries, the populations of total aerobic bacteria were reduced by 2.9 and 1.8 log CFU/g, respectively, compared to the control. In addition, the populations of yeast and molds were decreased by 1.8 and 1.2 log CFU/g, respectively. These results suggest that the combined treatment of 50 ppm $ClO_2$ and UV-C at a dose of 10 kJ/$m^2$ would be an effective technology for decontamination and improving the microbiological safety in celery and cherries during chilled storage.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.386-391
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• 2014

Atmospheric-pressure nonthermal corona discharge plasma was applied to the sterilization of biologically contaminated scoria powder. Escherichia coli (E. coli) culture solution was uniformly sprayed throughout the scoria powder for artificial inoculation, which was well mixed to ensure uniformity of the batch. The effect of the key parameters such as discharge power, treatment time, type of gas and electrode distance on the sterilization efficiency was examined and discussed. The experimental results revealed that the plasma treatment was very effective for the sterilization of scoria powder; 5-min treatment at 15 W could sterilize more than 99.9% of E. coli inoculated into the scoria powder. Increasing the discharge power, treatment time or applied voltage led to an improvement in the sterilization efficiency. The effect of type of gas on the sterilization efficiency was in order of oxygen, synthetic air (20% oxygen) and nitrogen from high to low. The inactivation of E. coli under the influence of corona discharge plasma can be explained by cell membrane erosion or etching resulting from UV and reactive oxidizing species (oxygen radical, OH radical, ozone, etc.), and the destruction of E. coli cell membrane by the physical action of numerous corona streamers.

• Fashion & Textile Research Journal
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• v.23 no.3
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• pp.406-414
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• 2021

This study aimed to evaluate the inhalation resistance(IR) and fiber structure of disposable masks when exposed to repeated heating and ultraviolet(UV) sterilization. The experiments consisted of a lab-scale and a field test. For the lab-scale test, KF94 and N95 masks were selected and a trial was composed of three repetitions of an 80-min sterilization. For the field test, a subject participated over four days, of which a KF94 was worn without sterilization, and the same trial was conducted during the next four days with daily sterilization. The results showed that the IR of the KF94 mask(9.5 Pa) gradually increased according to the sterilization up to the second repetition(15.6 Pa) but decreased at the third treatment(9.7 Pa). However, the N95 mask did not showany tendency of IR during the repetitions. Microscope photos showed several warped or blackened fibers in the stiffener layer after the repeated sterilization. After wearing a KF94 mask for four consecutive days, its IR decreased until the three days but increased the fourth day, whereas another KF94 mask with sterilization showed an increase in IR for the four days. In the microscope-photos after the consecutive four days, outside fibers and stiffener layers were warped or became less dense. In summary, the IR of the KF94 mask slightly increased through the three~four rounds of heating and UV sterilizations, but the fiber structures were not significantly deformed by the repeated sterilization. To reduce discarded mask waste, the repeated sterilization of masks can be recommended.

• Journal of Industrial Convergence
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• v.19 no.6
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• pp.67-72
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• 2021

The elevator installed in the building consists of an elevator call button and an input button for selection to the target floor. The elevator button is input only when the elevator user directly presses it. Such passenger input can be infected with an infectious disease due to contamination of the button. A non-contact button is required as a means for solving this problem, which detects the proximity of an object by applying a capacitive method. It implements a function of measuring the body's body temperature by attaching an infrared heat sensor, and provides a sterilization function of a button by attaching a UV-LED. A button was selected, a body temperature was measured through an infrared temperature measurement sensor, and UV-LED was turned on and sterilized when there was no user. The contactless elevator button is expected to be effective in preventing infectious diseases as it can prevent infection of viruses carrying infectious diseases and can detect body temperature to select positive patients of CIVID 19.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.11 no.2
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• pp.284-288
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• 2006

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.281-281
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• 2011

• The Journal of Natural Sciences
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• v.11 no.1
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• pp.41-44
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• 1999

For the purpose of improving the UV sterilization for toothbrush, the sterilizing effects by the UV light were studied. When toothbrushes were treated with the UV light for 5, 15, 30, 60 minutes, the sufficient antibacterial effect were shown after 15 minutes with 80% of bactericidal effects. To prevent the brownish stain on the sterilizer which was caused by the long exposure of UV light, no UV treatment for two hours after 15 minutes exposure were scheduled and then 3 minutes re-exposure were performed, which showed 97% of bactericidal effect. Also, the antibacterial effects of the sterilizer showed different results depending on the position of the toothbrush, it was recommended to adjust toothbrush to be exposed by the UV light directly.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.569-570
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• 2021

Hydroponic cultivation is of considerable interest to the production of high-quality green plants. However, establishing the planting operating systems in hydroponic cultivation may result in chronic problems, such as the reproduction of harmful bacteria throughout the circulating culture fluid. Extensive research has been conducted on using an ultraviolet sterilization system to prevent culture fluid contamination. In this study, the proposed module, using UV-C LEDs that emit wavelengths between 270 and 285 nm, was designed along with a sensor and controller. The module was set to emit 300, 500, and 700 mW, for different culture fluid flow rates, to investigate its capacity to eliminate Escherichia coli, Clavibacter michiganensis, Pseudomonas cichorii, and Fusarium oxysporum.