• Korean Journal of Materials Research
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• v.28 no.4
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• pp.208-213
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• 2018

Epitaxial ($11{\bar{2}}0$) a-plane GaN films were grown on a ($1{\bar{1}}02$) R-plane sapphire substrate with photoresist (PR) masks using metal organic chemical vapor deposition (MOCVD). The PR mask with striped patterns was prepared using an ex-situ lithography process, whereas carbonization and heat treatment of the PR mask were carried out using an in-situ MOCVD. The heat treatment of the PR mask was continuously conducted in ambient $H_2/NH_3$ mixture gas at $1140^{\circ}C$ after carbonization by the pyrolysis in ambient $H_2$ at $1100^{\circ}C$. As the time of the heat treatment progressed, the striped patterns of the carbonized PR mask shrank. The heat treatment of the carbonized PR mask facilitated epitaxial lateral overgrowth (ELO) of a-plane GaN films without carbon contamination on the R-plane sapphire substrate. Thhe surface morphology of a-plane GaN films was investigated by scanning electron microscopy and atomic force microscopy. The structural characteristics of a-plane GaN films on an R-plane sapphire substrate were evaluated by ${\omega}-2{\theta}$ high-resolution X-ray diffraction. The a-plane GaN films were characterized by X-ray photoelectron spectroscopy (XPS) to determine carbon contamination from carbonized PR masks in the GaN film bulk. After $Ar^+$ ion etching, XPS spectra indicated that carbon contamination exists only in the surface region. Finally, the heat treatment of carbonized PR masks was used to grow high-quality a-plane GaN films without carbon contamination. This approach showed the promising potential of the ELO process by using a PR mask.

• Journal of Environmental Health Sciences
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• v.30 no.5 s.81
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• pp.432-439
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• 2004

Korean certification regulation for particulate filtering respirators requires inward leakage (IL) test as European Standards (EN) and the standard levels of regulation are the same as those of EN. This study was conducted to evaluate particulate filtering respirators being commercially used in the market by using IL and assess the characteristics of IL. The study began with discussing the concept of IL, comparison of IL with fit test, and IL measurement method. Three brands of half masks and 10 brands of filtering facepieces (two top class, four 1st class and four 2nd class), total 13 brands respirators, and 10 test panels (subjects) who were classified in 9 facial grids in accordance with face length and lip length, were selected for IL test. IL tests were conducted in the laboratory of 3M Innovation Center which was established by EN standard. As expected ILs of half masks were lower than those of filtering facepiece mask. ILs of half masks and some filtering facepieces were significantly different in manufacturers. ILs of 1st class filtering facepieces were found to be much more than those of 2nd class and thus the result would cause wearers to get confused to select a mask. Four of six brands being no compliance with standards were thought that they should be tested again for certification because of a lot of differences from standards. There were no significant differences among ILs of five exercises. In 6 out of 13 brands lognormal distribution of ILs may be a better fit distribution and in 7 brands both lognormal and normal distributions were rejected. The result indicates that geometric mean may be better than arithmetic mean to establish standard.

• The Research Journal of the Costume Culture
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• v.28 no.3
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• pp.285-298
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• 2020

This study aimed at examining fashion consumers' awareness during the COVID-19 pandemic. Big data analysis methods, such as text mining, social network analysis, and regression analysis, were applied to user posts about fashion on Korean portal websites and social media during COVID-19. R 3.4.4, UCINET 6, and SPSS 25.0 software were used to analyze the data. The results were as follows. In researching the popular fashion-related topics during COVID-19, the prevention of infection and prophylaxis were significant concerns in the early stage (Jan 1 to Jan 31, 2020), and changed to online channels and online fashion platforms. Then, various topics and fashion keywords appeared with COVID-19-related keywords afterwards. Fashion-related subjects concerned prophylaxis, home life, digital and beauty products, online channels, and fashion consumption. In comparing fashion consumers' awareness during COVID-19 with SARS and MERS, "face masks" was the common keyword for all three illnesses; yet, the prevention of infection was a major consumer concern in fashion-related subjects during COVD-19 only. As COVD-19 cases increased, the search volume for face masks, shoes, and home clothes also increased. Consumer awareness about face masks shifted from blocking yellow dust and micro-dust to the sociocultural significance and short supply. Keywords related to performance turned out to be the major awareness as to shoes, and home clothes were repurposed with an expanded range of use.

• The Journal of the Korea Contents Association
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• v.2 no.3
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• pp.1-15
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• 2002

A noel automated brain region extraction method in single channel MR images for visualization and analysis of a human brain is presented. The method generates a volume of brain masks by automatic thresholding using a dual curve fitting technique and by 3D morphological operations. The dual curve fitting can reduce an error in clue fitting to the histogram of MR images. The 3D morphological operations, including erosion, labeling of connected-components, max-feature operation, and dilation, are applied to the cubic volume of masks reconstructed from the thresholded Drain masks. This method can automatically extract a brain region in any displayed type of sequences, including extreme slices, of SPGR, T1-, T2-, and PD-weighted MR image data sets which are not required to contain the entire brain. In the experiments, the algorithm was applied to 20 sets of MR images and showed over 0.97 of similarity index in comparison with manual drawing.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.3
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• pp.85-94
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• 2019

Purpose: The purpose of this study was to observe the degree of mask contamination in dental hygienist for general and oral bacteria and to identify areas of mask contamination after treatment. Methods: Masks were collected with every fifty dental hygienists who currently working in the department of preventive dentistry, prosthodontics, and orthodontics in Busan. The mask bacteria were collected in specific upper and side parts of the mask. Hand germs were collected using sterile cotton swabs, and then placed in a sterile conical tube. These were transferred to the laboratory. Hand germs and mask bacteria were incubated with nutrient broth (NB) and brain heart infusion broth (BHI) for 24 hrs and each cultured with NB and BHI plate at $37^{\circ}C$ for 48 hrs. Collected data were analyzed using the SPSS Window 20. Results: The number of bacteria was observed in the order of the department of preventive dentistry ($10.1{\times}10^5CFU/ml$), prosthodontics ($14.7{\times}10^5CFU/ml$), and orthodontics ($23.3{\times}10^5CFU/ml$) in the hand. In general bacteria, the difference of contamination was seen by the parts of the mask, but there was no significant difference. However, the oral bacteria were observed highly contaminated upper part of the mask in preventive dentistry. The mask contamination according to the medical departments was observed. Especially, the contamination of mask in preventive dentistry was significantly higher than other departments in oral bacteria. Conclusion: This study suggested that correct mask replacement and recognition of contamination areas can contribute to the prevention of infectious disease. and it would be necessary to increase hand hygiene performance to prevent cross-infection with masks. Also, this study may give an idea for making guidelines for mask management and supporting to establish clear criteria for the education program of personal protective equipment.

• Journal of the Korean Society of Clothing and Textiles
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• v.43 no.4
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• pp.579-591
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• 2019

This research investigated the needs analysis on consumers of fine dust masks to effectively develop a design prototype. Data were collected through focus group interviews on 32 individuals who have used fine dust masks. As a result, there is a new demand by consumers for technology based design changes that better fit the nose and face. Consumers preferred the smell and feel of traditional Korean paper. Young adults expressed the importance of masks that can be used for protection as well as fashion. The prototype improved the drawbacks of existing models using an origami-inspired design in a variety of colors, patterns and in sizes that are customized to fit the wearer. The proposed prototype is made of Dak felt fibers and jersey materials. It is characterized by downward-facing ear bands made of polyurethane to improve the fit around the ears and chin to more effectively block incoming air. The mask is foldable and has a crease that goes along the chin to increase the amount of enclosed space against the face making it easier to breathe compared to existing mask designs.

• Journal of Convergence for Information Technology
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• v.10 no.12
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• pp.156-165
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• 2020

330 Korean adult women were examined the correlation between degree of makeup and makeup satisfaction before/after wearing masks due to COVID-19 and the moderating effect of mandatory/voluntary goal-oriented attitude toward makeup. The study found that lip makeup(p<.001) was significant variable in makeup satisfaction before COVID-19, and eyebrow makeup(0<.002) was significant after COVID-19. Although moderating effect of mandatory goal-oriented attitude, which works between degree of makeup before/after COVID-19 and makeup satisfaction was not significant, but moderating effect of voluntary goal-oriented attitude appeared to be significant before(p<.000) and after(p<.000) COVID-19. And the degree of makeup after COVID-19 was lower than before(p<.000). If one believe that makeup is for one's own satisfaction, degree of makeup can be significant effect on the makeup satisfaction, but actual behavior has shown that degree of makeup has decreased since wearing masks because of COVID-19. I hope this research will be used as marketing material for beauty and cosmetics industry.

• Journal of Preventive Medicine and Public Health
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• v.54 no.1
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• pp.31-36
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• 2021

Objectives: Non-traditional materials are used for mask construction to address personal protective equipment shortages during the coronavirus disease 2019 (COVID-19) pandemic. Reusable masks made from surgical sterilization wrap represent such an innovative approach with social media frequently referring to them as "N95 alternatives." This material was tested for particle filtration efficiency and breathability to clarify what role they might have in infection prevention and control. Methods: A heavyweight, double layer sterilization wrap was tested when new and after 2, 4, 6, and 10 autoclave sterilizing cycles and compared with an approved N95 respirator and a surgical mask via testing procedures using a sodium chloride aerosol for N95 efficiency testing similar to 42 CFR 84.181. Pressure testing to indicate breathability was also conducted. Results: The particle filtration efficiency for the sterilization wrap ranged between 58% to 66%, with similar performance when new and after sterilizing cycles. The N95 respirator and surgical mask performed at 95% and 68% respectively. Pressure drops for the sterilization wrap, N95 and surgical mask were 10.4 mmH2O, 5.9 mmH2O, and 5.1 mmH2O, respectively, well below the National Institute for Occupational Safety and Health limits of 35 mmH2O during initial inhalation and 25 mmH2O during initial exhalation. Conclusions: The sterilization wrap's particle filtration efficiency is much lower than a N95 respirator, but falls within the range of a surgical mask, with acceptable breathability. Performance testing of non-traditional mask materials is crucial to determine potential protection efficacy and for correcting misinterpretation propagated through popular media.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.576-581
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• 2021

In the post-epidemic era, COVID-19 has not yet been fully controlled. Wearing masks is still the main means of epidemic prevention, and the negative effects brought by masks continue to continue. Wearing a mask for a long time can cause two problems. The first problem is hypoxia, and the other is an increase in psychological stress. To reduce the negative impact of masks, this paper proposes a new breathing mode. It is the "Umm~" vocal breathing mode, which simultaneously solves the two problems of hypoxia and increased stress. This paper explores the reasons why new breathing patterns can relieve stress. Explains the relationship between HRV and stress index and uses SDNN as an indicator to detect stress index to confirm the effectiveness of this breathing pattern. Experimental results prove that the "Umm~" vocal breathing mode can not only relieve the stress induced by wearing a mask. And when not wearing a mask, it can also be used to relieve daily stress. This method that anyone can easily implement should be more popularized.

• The Korean Journal of Pain
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• v.34 no.2
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• pp.241-245
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• 2021

Background: It has been reported that a new type of headache may develop as a result of face mask use during the COVID-19 pandemic. The aim of this study is to investigate the clinical features of face mask-related headache during the COVID-19 pandemic. Methods: This is a cross-sectional study carried out on healthcare workers at the Afyonkarahisar Health Sciences University. The number of workers at our university was established. Sample size was calculated using the G*Power program. A questionnaire consisting of questions relating to pre-existing headache, an aggravation in headache, and de-novo headache was filled out by 3 neurologists with all participants. Results: Data was collected from a total of 375 participants, after the exclusion of 5 individuals who refused to participate. Out of all participants, 26 (6.9%) used a filtering mask, 274 (73.1%) used a surgical mask, 75 (20.0%) participants used a combination of both masks. The number of participants with preexisting headache was 114 (30.4%) had pre-existing headache. Of those with pre-existing headache, 77 (67.5%) healthcare workers had reported an aggravation in their headache after mask use. De-novo headache was observed in 116 (30.9%) of participants. De-novo headache characteristics included throbbing in 17 (14.7%) participants and pressing in 99 (85.3%) participants. In addition, symptoms such as tachypnea, sleep disturbance, and fatigue were found to be significantly higher. Conclusions: This study indicates that healthcare workers develop headaches due to use of masks during the COVID-19 outbreak.