• 대한치과의료관리학회지
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• 제10권1호
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• pp.33-41
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• 2022

The purpose of this study was to investigate the correlation between wearing masks and subjective symptoms of halitosis in the COVID-19 situation. The survey was conducted from June 15 to July 31, 2022, among university students aged 19 years or older in Daegu and Gyeongbuk, 1. Subjective symptoms of halitosis were found to be higher in males and students being treated for periodontal diseases. 2. The subjective symptoms of halitosis were found to be higher in subjects with psychological anxiety, even though they did not have halitosis. 3. As a result of examining the subjective symptoms of halitosis, it was found that there were more subjects who were aware of halitosis while wearing a mask than those who were not. In view of the above results, it is thought that because of prolonged wearing of masks due to the COVID-19 pandemic situation, the difficulty faced in oral health management increases the symptoms of halitosis. Therefore, it is considered that oral health education in the era of corona should be accompanied by proper wearing of masks and halitosis management education.

• 한국의류학회지
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• 제36권2호
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• pp.194-205
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• 2012

Historically, garments have been spontaneously made with human instinct in order to warm and decorate the body using textiles that have been made and used by various peoples in different cultures. Contemporary garments have been used as a means of warming as well as express individual personality and a desire to pursue beauty. They have a unique formativeness and a symbolic nature according to cultural phenomena that reflect a cultural outcome that expresses contemporary thinking and ideology as well as their aesthetic consciousness. This study globally promotes Chinese opera mask culture and proposes the possibility of creative thinking through the introduction of Chinese opera mask elements into contemporary fashion, expressing them as patchworks. In order to endow artistic value (required in contemporary fashion) this study creates works by analyzing and applying a formative sense seen in patchwork techniques and the characteristics of Chinese opera masks; in addition, it sought the possibility of new expressions in garment designs. The results obtained from the research involve the following. First, the introduction of the traditional patchwork technique to contemporary garments may be a dynamic theme of garment expression and exceed stereotypical ideas that enable the creation of designs attuned to the globalization era. Second, it was possible to pursue independent formativeness which is in harmony with a modern sense through the restructuring of the harmony of colors and practical characteristics found in patchworks. Third, it was possible to demonstrate their artistry and unique effect in the expression of contemporary garments by the expression of the analyzed results of characteristic patterns of Chinese opera masks with a patchwork technique in creating works. Results show that it is necessary to conduct research into a patchwork technique that applies diverse materials as a new method to develop contemporary garment design also as a creative design. In addition, if the analyzed results of the characteristic patterns of Chinese opera masks can be expressed with a patchwork technique, they may be able to exhibit a genuine effect along with the artistry of expression in contemporary garments; thereby, relevant follow-up research should be further continued.

• 한국입자에어로졸학회지
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• 제15권4호
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• pp.191-202
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• 2019

In this study, performance (particle removal efficiency and breathing resistance) of several commercially available face masks (electrostatic filter masks (KF80 certified), a nanofiber filter mask (KF80 certified), and an uncertified mask) with their filter structure and composition were evaluated. Also, effects of relative humidity (RH) of incoming air, water and alcohol exposure, and reusability on performance of face masks were examined. Monodisperse and polydisperse sodium chloride particles were used as test aerosols. Except the uncertified mask filter, PM_2.5 removal efficiency was found to be higher than 90%, and the nanofiber filter mask had the highest quality factor due to the low pressure drop and high removal efficiency (nanofibers were arranged in a densely packed pore structure and contained a significant amount of fluorine in addition to carbon and oxygen). In the case of the KF80 certified mask, the removal efficiency was little affected when the RH of incoming air increased. When the mask filters were soaked in water, the removal efficiency of mask filters was degraded. In particular, the uncertified mask filter showed the highest removal efficiency degradation (26%). When the mask was soaked in alcohol, the removal efficiency also decreased with the greater degree than the water soaking case. The nanofiber mask filter showed the strongest resistance to alcohol exposure among tested mask filters. During evaluation of reusability of masks in real life, the removal efficiency of certified mask filter was less than 4% for 5 consecutive days (2 hours per day), while the removal efficiency of uncertified mask filter significantly decreased by 30% after 5 days.

• 한국산업보건학회지
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• 제31권4호
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• pp.427-439
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• 2021

Objectives: This study aims to investigate differences in microbial contamination according to the duration and environment of mask wearing. Methods: Forty-five participants were recruited from workers in an offices, multi-purpose facilities, and a schools. After wearing of KF94 mask for two. four, and six hours, the microorganisms adsorbed on the outer and inner layers of the mask were inoculated on BAP(Blood Agar Plate), Chocolate agar, and SDA plates. The bacterial count (CFUs: colony-forming units) cultured in each plate was measured and analyzed for changes in filtration efficiency. Results: The microbial contamination of masks worn in classrooms, offices, and multi-purpose facilities showed a significant difference depending on the environment (p<0.000). The measured CFUs increased significantly according to the time wearing the mask. The difference between the inner and outer layers of the mask was also significant (p<0.05). However, there was no statistical difference in the filtration efficiency of the masks by duration time (p=0.515). Conclusions: Masks worn by workers in the offices, multi-purpose facilities, and schools showed an increase of microbial contamination with the amount of time wearing the mask. The results indicate that the masks used in daily life may have adverse health effects if they are worn for a long time or reused over several days without the realizing that the masks can be contaminated with biological hazards. Guidelines on the safe threshold time for mask use should be established through further research.

• ETRI Journal
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• 제34권6호
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• pp.958-961
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• 2012

In this letter, we present a new algorithm for the harmonic and percussive separation of jazz music. Using a short-time Fourier transform and nonnegative matrix factorization, the signal is decomposed into rank components. Each component is then split into harmonic and percussive parts using masks calculated based on their tonalities. Finally, the harmonic and percussive parts are separated after applying the masks and a summation. We evaluate the algorithm based on real audio examples using both objective and subjective assessments. The proposed algorithm performs well for the separation of harmonic and percussive parts of jazz excerpts.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.462-482
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• 2014

This paper proposes a new resampling detection method for images that detects whether an image has been resampled and recovers the corresponding resampling rate. The proposed method uses a given set of zeroing masks for various resampling factors to evaluate the convolution values of the input image with the zeroing masks. Improving upon our previous work, the proposed method detects more resampling factors by checking for some periodicity with an approximate detection mechanism. The experimental results demonstrate that the proposed method is effective and efficient.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1240-1243
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• 2003

In this paper, an encryption method to share a secret binary image is proposed. It divides the image to be encrypted into an arbitrary number of images and encrypts them using XOR process with different binary random images which was prepared by the means of the XOR process, too. Each encrypted slice image can be distributed to the authenticated ones. However, we transfer the encrypted images to the binary phase masks to strengthen the security power, that means phase masks can not be copied with general light-intensity sensitive tools such as CCDs or cameras. For decryption, we used the Mach-Zehnder interferometer in which linearly polarized two light beams in orthogonal direction, respectively. The experimental result proved the efficiency of the proposed method.

• 한국산업융합학회 논문집
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• 제20권4호
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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.

• 한국정밀공학회지
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• 제14권9호
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• pp.22-29
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• 1997

This paper describes a three dimensional profile measurement method for sheet metal products which have flexible and porous sculptured surfaces. Shadow masks are used as measuring objects for practical implementation or this study. The shadow masks are located inside the fluorescent glasses of monitors for televisions or computers and used to prevent electron guns from interfering between pixels. Three dimen- sional surface profiles are measured by adopting a software autofocusing technique to capture focused images. The experimental results show that the method is very effecive and suitable for sheet meal prod- ucts with flexible and porous surfaces.

• 전자공학회논문지B
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• 제33B권2호
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• pp.77-87
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• 1996

Existing area-based stereo matching algorithms utilize a single rectangular correlation area for computing cross-correlation between corresponding points in stereo images, and compute disparity by finding the peak in the vicinity of depth discontinuity, since, because of inconstnat disparities around discontinuities, the cross-correlation becomes low in such area. Inthis paper, a new area-based matching strategy is proposed exploiting multiple directional correlation masks instead of a single one. The proposed technique computes multiple cross-covariance functions using each oriented mask. Peaks are detected from each covariance function and the disparity is computed by choosing the location with the highest covariance value. Proposed approach can also be applied to compute disparity gradients without obtaining dense depth data. A number of examples are presented using synthetic and natural stereo images.