• Journal of the Korean Society of Industry Convergence
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• v.20 no.4
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• pp.339-343
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• 2017

Masks are a portable functional product for daily use. They can protect user health by filtering harmful fine particles in the air. In the past decade, there have been approximately 10 yellow dust incidences per year, amounting to a total duration of 20 days, and they continue to increase year after year. In addition, the frequency of yellow dust incidences in Korea has increased by more than four times compared to levels from the 1970s. Statistical reports indicate that annual damages caused by yellow dust amount to more than six trillion KRW. This study developed a zero-fog multi-layer mask with a collection efficiency and yellow dust and particulate matter filtration areas that are at least thrice as effective as existing masks. The new mask also reduces pressure drag by half.

• The Korean Journal of Emergency Medical Services
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• v.16 no.2
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• pp.67-74
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• 2012

Purpose : The purpose of this study is to get basal user guidelines of safer bag-valve-mask application on patient with normal pulmonary patho-physiologic condition. Methods : This study was accomplished by pre-qualified 25 EMS junior grade students. Participants were instructed randomly compress bag to one-third, half and total and also with differesnt compression speed. Resultant tidal volumes and mean airway pressures obtained in RespiTrainer were analysed in relation to the each compression depth and rate. Results : Demographic difference does not affect tidal volume with any compression depth and rate change. Increasing compression depth is correlated with tidal volume increasement at any compression rate and also with mean airway pressure. If the compression depth is same, compression rate change did not affect significantly the resultant tidal volume or mean airway pressure. Conclusion : Hand size, Experience, BMI dose not affect tidal volume. Compress the 1600 ml bag half to total amount is safe way to offer sufficient tidal volume without risky high airway pressure delivery to patient airway who with normal lung patho-physiologic condition.

• 전자공학회논문지 IE
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• v.48 no.2
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• pp.1-5
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• 2011

The epitaxial GaN layer of $120{\mu}m$ ~ $300{\mu}m$ thickness with a stripe Ti mask pattern is performed by hydride vapor phase epitaxy(HVPE). Ti strpie mask pattern is deposited by DC magnetron sputter on GaN epitaxial layer of $3{\mu}m$ thickness is grown by hydride vapor phase epitaxy(HVPE). Void are observed at point of Ti mask pattern when GaN layer is investigated by scanning electron microscope. The Crack of GaN layer is observed according to void when it is grown more thick GaN layer. The full width at half maximum of peak which is measured by X-ray diffraction is about 188 arcsec. It is not affected its crystallization by Ti meterial when GaN layer is overgrown on Ti stripe mask pattern according as it is measure FWHM of overgrowth GaN using Ti material against FWHM of first growth GaN epitaxial layer.

• Fashion & Textile Research Journal
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• v.24 no.4
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• pp.399-407
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• 2022

Wearing a mask is essential during the ongoing COVID-19 pandemic. For this study, an online survey was conducted on the actual use of masks among adults in their twenties and older. We used 389 questionnaires for the final analysis, excluding insincere or incomplete questionnaires. We then analyzed the responses using descriptive statistical analysis, frequency analysis, t-test, and ANOVA. More than half of the respondents indicated that they wore a mask for five to ten hours a day, with KF masks being the most frequently used. Participants who most frequently used cloth masks were more likely to consider color, design, and eco-friendliness, while those who used KF masks were more concerned with price and safety. There was no significant difference in purchase satisfaction between mask types, but the purchase intention was higher for KF masks. When purchasing a KF mask, there were significant differences across genders in terms of price and eco-friendliness preferences. There were also significant differences across age groups in price, eco-friendliness, skin irritation, and comfort preferences. Previous studies have shown a significant difference in gender and age in terms of preferred mask colors and designs. However, this survey found no significant difference across these categories. These findings indicate those mask manufacturers should consider safety and eco-friendliness over mask color and design.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.04a
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• pp.38-40
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• 1999

• Journal of the Korean Wood Science and Technology
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• v.50 no.6
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• pp.490-498
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• 2022

The current study aimed to verify the image segmentation ability of rays in tangential thin sections of conifers using artificial intelligence technology. The applied model was Mask region-based convolutional neural network (Mask R-CNN) and softwoods (viz. Picea jezoensis, Larix gmelinii, Abies nephrolepis, Abies koreana, Ginkgo biloba, Taxus cuspidata, Cryptomeria japonica, Cedrus deodara, Pinus koraiensis) were selected for the study. To take digital pictures, thin sections of thickness 10-15 ㎛ were cut using a microtome, and then stained using a 1:1 mixture of 0.5% astra blue and 1% safranin. In the digital images, rays were selected as detection objects, and Computer Vision Annotation Tool was used to annotate the rays in the training images taken from the tangential sections of the woods. The performance of the Mask R-CNN applied to select rays was as high as 0.837 mean average precision and saving the time more than half of that required for Ground Truth. During the image analysis process, however, division of the rays into two or more rays occurred. This caused some errors in the measurement of the ray height. To improve the image processing algorithms, further work on combining the fragments of a ray into one ray segment, and increasing the precision of the boundary between rays and the neighboring tissues is required.

• Safety and Health at Work
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• v.13 no.3
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• pp.364-371
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• 2022

Background: Respiratory masks can provide healthcare workers with protection from biological hazards when they have good performance. There is a direct relationship between the visual specifications of a mask and its efficacy; thus, the aim of this study was to develop tools for qualitative assessment of the performance of masks used by healthcare workers. Methods: A mixed-methods design was used to develop a qualitative assessment tool for medical face masks (MFM) and particle filtering half masks (PFHM). The development of domains and items was undertaken using observation and interviews, the opinions of an expert panel, and a review of texts and international standards. The second phase evaluated the psychometric properties of tools. Finally, the validated Mask Qualitative Assessment Tools (MQAT) were used to assess six samples from 10 brands of the two types of masks. Results: MQAT-MFM and MQAT-PHFM shared 42 items across seven domains: "cleanliness," "design," "marking, labeling and packaging," "mask layers," "mask strap," "materials and construction," and "nose clip." MQAT-MFM included one additional item. MQAT-PHFM included another nine items associated with an eighth "Practical Performance" domain, and the valve version had another additional "Exhalation Valve" domain and six items. The evaluation indicated 80% compliance for MFM and 71% compliance for PFHM. "Marking, labeling and packaging" and "Layers" were associated with the least compliance in both types of masks and should be checked carefully for defining mask quality. Conclusion: MQAT can be used for immediate screening and initial assessment of MFM and PHFM through appearance, simple tools, and visual inspection.

• Journal of Korea Multimedia Society
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• v.1 no.2
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• pp.183-193
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• 1998

Color inverse halftoning is the transformation of a color-halftone image to a continuous-tone color image that is more natural in human vision. In this paper, we propose a new smoothing mask that can remove halftone patterns in channel effectively and we apply it to color inverse halftoning. The proposed smoothing mask can make channel images more smooth and natural in human vision than traditional ones. Its characteristic can be adapted automatically according to the various color halftone images. We analyze the result images in various aspects through experiments. Experimental results show that the mask is useful for color inverse halftoning. It can be applied to field of multimedia application, such as desktop publishing, color facsimile and digital library construction.

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1266-1276
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• 2021

The mask parameters of a coded aperture are critical design features when optimizing the performance of a gamma-ray camera. In this paper, experiments and Monte Carlo simulations were performed to derive the minimum detectable activity (MDA) when one seeks a real-time imaging capability. First, the impact of the thickness of the modified uniformly redundant array (MURA) mask on the image quality is quantified, and the imaging of point, line, and surface radiation sources is demonstrated using both cross-correlation (CC) and maximum likelihood expectation maximization (MLEM) methods. Second, the minimum detectable activity is also derived for real-time imaging by altering the factors used in the image quality assessment, consisting of the peak-to-noise ratio (PSNR), the normalized mean square error (NMSE), the spatial resolution (full width at half maximum; FWHM), and the structural similarity (SSIM), all evaluated as a function of energy and mask thickness. Sufficiently sharp images were reconstructed when the mask thickness was approximately 2 cm for a source energy between 30 keV and 1.5 MeV and the minimum detectable activity for real-time imaging was 23.7 MBq at 1 m distance for a 1 s collection time.

• Safety and Health at Work
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• v.13 no.4
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• pp.500-506
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• 2022

This study evaluated the consistency between two quantitative fit test devices with different methods of ambient aerosol counting. Three types of respirators (N95, half mask, and full facepiece) were worn by 50 participants (male, n = 25; female, n = 25), PortaCount (Pro+ 8038) and MT (05U) were connected to one probe to one mask, and fit factors (FFs) were measured simultaneously with the original and modified protocols. As a result of comparing MT FFs with PortaCount FFs as references and by applying for the pass/fail criteria (FF = 100), the consistency between the two devices for half masks and full facepieces was very high. N95 was somewhat weaker than the two type of respirators in the consistency; however, the correlation between the two devices was very strong (p < 0.0001). The results showed that an FF of 100 as measured by PortaCount was likely to be measured as 75 by the MT. Therefore, when performing the fit test for N95 using the MT and pass level of FF 100, a certain level of adjustment is necessary, whether end-user or putting a scaling factor by manufacturer.