• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.275-279
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• 2011

Sterilization of Escherichia coli (E. coli) is examined using a unique pulsed ultra-violet (UV) elliptical reactor based on Nd:YAG laser resonator, UV radiation from a pulsed xenon flashlamp. The light from the discharge has a broadband emission spectrum extending from the UV to the infrared region with a rich UV contained. Sterilization method by using the UV light is fast, environment-friendly and it does not cause secondary pollution. A Nd:YAG laser resonator having elliptical shape has advantage of concentrating the radiation of the UV light at two foci as the quart sleeve filled with E. coli. The primary objective of this research is to determine the important parameters such as pulse per second (pps), the applied voltage for sterilizing E. coli by using an UV elliptical reactor. From the experiment result, the sterilization effect of UV elliptical reactor is better than that of UV cylindrical reactor, and it can be 99.9% of sterilization at 800V regardless of the pps within 10 minutes.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.266-274
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• 2023

Recently, sterilization technology has received increasing interest due to the COVID-19 pandemic and required safety precautions. Particularly, sterilization devices using near ultraviolet (UV) with a 405 nm wavelength are also drawing attention. It has a UV-C wavelength and other sterilization effects. Its blue-colored light on the boundary between UV and visible light is used as a light-emitting diode (LED) lamp for 405 nm sterilization, owing to its longer wavelengths than UV rays. However, the 405 nm wavelength contains blue light that can damage the eyes and skin during prolonged exposures and affect the emotional and biological parts of the body. Currently, 405 nm sterilization LED light registers are circulating in the market. However, they have not undergone safety tests for blue-light hazards. Thus, with the active distribution of sterilization LED lights, solid safety standards and management systems are essential to protect users from blue-light hazards. Accordingly, in this study, we conducted spectral radiance and spectral radiative luminance tests on 405 nm sterilization LED registers available in the market by the measurement criteria of IEC 62471. Safety standards must be established to secure users' safety against blue light hazards at a time when 405nm sterilization LED lights are actively distributed due to COVID-19.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.567-568
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• 2021

In this paper, we design, fabricate, and test the performance of a cabin filter with LED modules of composite wavelengths containing UV-A and UV-C. Germs and air farms of the manufactured cabin filter confirmed sterilization capability in the sterilization test, and special chambers were manufactured to verify organic material decomposition capability in the organic compound decomposition test. Using colkates as photocatalytic was proved to be superior to using metal mash. The sterilization and air purification capabilities of the cabin filter produced throughout this study were verified through a similar environmental test.

• 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 the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.6
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• pp.15-20
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• 2014

Recently, LED (Light Emitting Diode) application research is studying by using a specific wavelength. LED plant factory produced a lot of green plants in a closed spaces, so it should be taken to guard against harmful microbes. Until today, a lot of studies for green plant production in plant factory is proceed but there were no study on harmful microbes in plant factory. Thus, the analysis on sterilization for harmful microbes in plant factory were experimented using UV (Ultra Violet) LED with 282nm of wavelength. As a results on sterilization of three harmful microbes, 50% of sterilization efficiency was achieved after 2.5 hours, 97% was achieved after 12 hours of UV LED irradiation, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.1
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• pp.67-70
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• 2022

In the present work, we have designed to optimize the optical filter structures of the 1-dimensional photonic quasicrystals (1D PQCs) characteristic for the COVID-19 UV sterilization. The simulator using MATLAB program and ourselves manufacturing calculation codes. After making the aperiodic (and complexed) multi-layer structure model, we establish the transfer matrix method (TMM) for model by the operator conversion. By the using the MATLAB, we derive a matrix for the designed complexed multi-layer structure by applying the equations to the model by obtaining the reflectance and transmittance from the matrix. We also prove the possibility of application in optical filter for UV sterilization.

• Journal of Mushroom
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• v.13 no.3
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• pp.256-261
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• 2015

This study was conducted to reduce contamination ratio of oyster mushroom bottle cultivation. The optimal conditions of substrate sterilization for reducing of contamination ratio were at $121^{\circ}C$ for 90 min. In addition, UV-C irradiation is good for lower contamination ratio to continue over 6 hours at cooling and inoculation room after sterilization. The contamination ratio and density of microorganisms of substrate were showed 0% after sterilization at $121^{\circ}C$ for 90 min. Trichoderma sp., main pathogen of mushrooms, was detected from substrate after sterilized during 2 or 4 hours at $101^{\circ}C$ and $105^{\circ}C$, respectively. The amount of electricity used was the lowest at $121^{\circ}C$ for 90 min than that of other sterilization conditions. The UV-C irradiation treatment was used UV-C lamp(40 watts) in the inoculation room($56m^3$). The density of bacteria did not detected after UV-C irradiation for 6 hours. And the death ratio of bacteria and Trichoderma sp. was 99.9% after UV-C irradiation for 6 hours. However, in the same UV-C irradiation time, the death ration of Cladosporium sp. was 90.9%. Therefore, the death ratio of fungi was lower than that of bacteria at the same UV-C irradiation treatment.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.9
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• pp.931-937
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• 2012

In this study, we assessed environmental impacts of compound humidifiers using environmental life cycle assessment and presented the ways to improvements in energy consumption of them. We found eco-design parameters and $CO_2$-eq emissions in each stage of raw material acquisition, manufacturing, transportation, use and disuse in life cycle of the compound humidifiers. The highest $CO_2$ emission is found to be in the stage of use among all stages of life cycle, which is mainly due to power consumption in thermal heating of heating coil for sterilization during humidification. The power consumption and $CO_2$ emission in the stage of use can be reduced to 1/4 and 1/3 at the highest estimate through improvement of sterilization method, respectively. We suggested the replacement of conventional thermal heating coil by ultra violet light-emitting diodes (UV-LED) for sterilization and then presented the experimental results on the sterilization effects of UV-LEDs.

• Journal of Radiation Industry
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• v.8 no.2
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• pp.133-140
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• 2014

The sterilization of health care products is widely used to choose conventional Ethylene Oxide gas sterilization in South Korea. But the method has brought serious issues because of the toxic residual gas and global warming of $CO_2$ evacuation after the sterilization process. This study is carried out to confirm the application possibility of gamma sterilization instead of Ethylene Oxide in sanitary aid products. Four kinds of products (gauze, menstrual pad, bandage, menstrual tampon) were treated with gamma irradiation of 15 kGy, then analyzed the achievement of the sterility assurance level (SAL) $10^{-6}$ through BI test. The cytotoxicity of accelerated samples of 6 months elapse evaluated by means of colony forming rate at various concentration of the extracts. pH and UV measurements at extract concentrations were tested according to the MFDS (Ministry of food & drug safety) guideline to verify a stability & safety of product sterilized. The results revealed that the extracts did not show any significant changes in cytoxicity assay as well as pH and UV values by gamma sterilization. All extract concentration was observed high cell viability, pH and UV values were calculated within the acceptable range prescribed by the guideline. It indicates that gamma sterilization could effectively substitute for conventional sterilization such as Ethylene Oxide sterilization in the sanitary aid products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.3
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• pp.461-466
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• 2010

A cylindrical UV sterilization system was developed to decrease microorganisms in centrifuged Takju (CT). CT was run through 110 strips of honey comb type-teflon tubes and 9 UV lamps (1395 W) were equipped between teflon tubes. The optimum sterilization condition of CT was fixed for 1.5 min at 2 L/min in overall quality aspects; also, 5~6 log cycle decrease of viable cell numbers of total bacteria and yeast was observed at this operating condition. Quality changes of UV-sterilized CT were examined by UV irradiation of CT followed by storing at $30^{\circ}C$ for 8 days. To evaluate quality changes of UV-sterilized CT, pH, amino nitrogen content, acidity, reducing sugar content and viable cell numbers of total bacteria and yeast were measured. The growth of yeast and bacteria was retarded, showing around $10^8\;CFU/mL$ even after 4 days and $10^8\;CFU/mL$ after 6 days, respectively. Also, UV sterilized CT showed no changes in pH, titratable acidity, and amino nitrogen content during storage except reducing sugar content. UV sterilization did not cause significant difference in L, a, and b values between CT and UV-sterilized CT over the storage period.