• Journal of Technologic Dentistry
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• v.33 no.1
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• pp.93-102
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• 2011

Purpose: The study aimed to evaluate working environment for dental technician by measuring dust level, ventilation conditions and the use of personal protective equipment and to provide basic information required to improve working environment and develop health education programs for dental technician. Methods: A total of 240 dental technician who are registered with the Daegu Association of Dental technician and working at 34 dental laboratories participated in the study. And the dust level was measured at 21 different spots in 16 dental laboratories out of 34. Results: Of 34 dental laboratories, 31 (91.2%) were equipped with a ventilator, but the remaining 3 (8.8%) did not have a ventilator. By the number of ventilator, 1 to 3 ventilators were found in 22 dental laboratories (71.0%), 4 to 6 ventilators were in 7 laboratories (22.5%) and more than 7 ventilators in 2 laboratories(6.5%). According to the frequence of changing filters in dust collector, 20 dental laboratories (58.9%) changed filters every four weeks, 10 laboratories (29.4%) changed them every six weeks and 4 laboratories (11.7%) changed them every eight weeks. Of total respondents, 114 (61.3%) said they wore a mask all the time while working, 56 (29.6%) said they frequently wore a mask, 19 (10.1%) said they did not wear a mask. As for the type of masks, 159 (84.1%) used a disposable mask, 25 (13.2%) used a cotton mask and 5 (2.7%) used an anti-dust mask. For dust sat on their outfits while working, 102 (54.0%) shook their uniforms inside workplace to keep dust off the uniforms, 64 (33.9%) did not anything until they wash their uniforms and 23 (12.1%) shook their uniforms outside workplace to keep dust off the uniforms. Of total respondents, 182 (96.3%) had a particle in their eyes while carrying out grinding work. Based on the measurement of floating dust at workplace, 3 dental laboratories showed dust concentration exceeding the minimum level of 10 mg/$m^3$ allowed under the permit for environment. Of those, 1 laboratory had the dust concentration that was more than 1.5 times higher than the minimum level. Dust concentration was higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. Dust comprised of nickel (more than 70%), chrome (9%) and others. The mean chrome concentration was more than twice higher than the minimum permissible level of 0.5 mg/$m^3$. There were two laboratories that showed chrome concentration exceeding the level of 0.4 mg/$m^3$. Like dust concentration, chrome level was higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. There were six laboratories that had nickel concentration exceeding the minimum permissible level of 1 mg/$m^3$. Of those, one laboratory had nickel concentration that was more than three times higher than the minimum permissible level. Nickel concentration was also higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. Conclusion: It is not likely that heavy metal concentrations found in the study constitute respiratory dust. It is however necessary for health of dental technician to apply the Industrial Safety and Healthy Law to dental laboratories and make recommendations for the use of personal protective equipment, installation of a proper number of ventilators, more frequent change of filters in dust collector and improved ventilation for polishing work. At the same time, dental technician need education on how to use personal protective equipment and how to efficiently remove dust from their uniforms.

• Journal of Environmental Health Sciences
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• v.41 no.3
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• pp.203-215
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• 2015

Objectives: This study was designed to evaluate the filtration efficiencies and pressure drops of five commercial cloth masks (4 plate type, 1 cup type) in comparison to the performance of a class 1 disposable respirator (reference respirator). A further objective was to evaluate the effects of the number of layers and wash treatment independently on filtration efficiencies and pressure drops. Methods: Polydisperse NaCl aerosols were generated in an aerosol chamber and their concentrations were measured by an optical particle counter (OPC) in the size range of $0.3{\sim}10{\mu}m$ (five channels). Results: The filtration efficiencies of the five cloth masks and the reference respirator were D: 9.5%, C: 18.5%, E: 23.6%, A: 28.5%, B: 29.7% and R: 91.1%, respectively, and the pressure drops through them were C, D: 0.8 Pa, E: 1.7 Pa, B: 6.4 Pa, A: 42.7 Pa and R: 19.3 Pa, respectively. The filtration efficiencies of the cloth masks and reference respirator were below the class 1 respirator criterion (${\geq}94.0%$) of the Ministry of Employment and Labor (MOEL) and Ministry of Food and Drug Safety (MFDS). The pressure drops satisfied the class 1 respirator criterion (${\leq}70Pa$) of MOEL and MFDS. When the cloth masks were folded into two and four layers, the filtration efficiencies of cloth masks A, B, C, D (plate type) increased 1.7-4.6 times, and 2.3-6.8 times, respectively, compared to the efficiencies of the same products in a single layer. Pressure drops increased as the number of layers was increased. The filtration efficiency of cloth mask E with a liner was 1.3 times higher than that of the same mask without a liner, and the pressure drop was lower in the no-liner configuration. After a single washing, the filtration efficiencies of all the cloth mask products decreased 1.04-4.0 times compared to those of the same products intact. For the cloth masks C and E, their filtration efficiencies were significantly decreased after washing (p<0.05). The pressure drops of all cloth masks were 1.2-2.0 times lower after washing. Conclusions: The filtration efficiencies of the five cloth masks were below 30% and did not improve greatly by increasing the number of layers. After a single washing, their performances decreased. Considering the above and other issues identified with cloth masks, such as poor fit and stretched fibers through use, people should not expect protection against particulate matters from the cloth masks on the market.

• Journal of the Korean Society of Radiology
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• v.15 no.1
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• pp.21-28
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• 2021

Computed tomography (CT) has the problem of having more radiation exposure compared to other radiographic apparatus. There is a low-dose imaging technique for reducing exposure, but it has a disadvantage of increasing noise in the image. To compensate for this, various noise reduction algorithms have been developed that improve image quality while reducing the exposure dose of patients, of which the median modified Wiener filter (MMWF) algorithm that can be effectively applied to CT devices with excellent time resolution has been presented. The purpose of this study is to optimize the mask size of MMWF algorithm and to see the excellence of noise reduction of MMWF algorithm for existing algorithms. After applying the MMWF algorithm with each mask sizes set from the MASH phantom abdominal images acquired using the MATLAB program, which includes Gaussian noise added, and compared the values of root mean square error (RMSE), peak signal-to-noise ratio (PSNR), coefficient correlation (CC), and universal image quality index (UQI). The results showed that RMSE value was the lowest and PSNR, CC and UQI values were the highest in the 5 x 5 mask size. In addition, comparing Gaussian filter, median filter, Wiener filter, and MMWF with RMSE, PSNR, CC, and UQI by applying the optimized mask size. As a result, the most improved RMSE, PSNR, CC, and UQI values were showed in MMWF algorithms.

• Korean Journal of Psychosomatic Medicine
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• v.32 no.1
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• pp.10-23
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• 2024

This study examines the changes in attractiveness and social perception of mask wearers during the COVID-19 pandemic. Before COVID-19, masks were seen as a sign of infection, decreasing the wearer's attractiveness. However, with the widespread normalization of mask-wearing during the pandemic, the perception mechanisms have become more complex. The attractiveness and social perception of mask wearers now vary based on factors such as the wearer's baseline attractiveness, race, and attitudes toward masks. Consequently, research findings on perception changes due to mask-wearing have been inconsistent. This inconsistency is due to the lack of standardized experimental methods and the failure to account for individual differences among participants, as well as insufficient theoretical background in the studies. From a psychiatric perspective, it is essential to formulate and test new hypotheses centered around the psychological mechanisms related to the human behavioral immune system when studying attractiveness perception during a pandemic. Notably, attention should be given to how differences in the activation of individuals' behavioral immune systems influence perceptions of mask wearers. Understanding these dynamics can provide crucial insights into how social perceptions and aversions impact mental health, thereby shedding light on various psychiatric issues that arise during infectious disease outbreaks.

• Journal of Nutrition and Health
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• v.43 no.5
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• pp.453-462
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• 2010

The effects of unripe apple mask pack made from unripe apple extracts on the skin status of middle-aged women for 4 weeks were investigated. The subjects were divided into three groups: placebo mask pack as the control (PM, n = 8), apple mask pack (AM, n = 16), and apple mask pack + apple intake (AAM, n = 12). The study included a survey questionnaire, and evaluations of nutrients intakes and of skin status. Skin status was measured by Aramo-TS. After 4 weeks, facial moisture, elasticity, evenness, and wrinkle level were improved in AM and AAM. The facial moisture level (AM: $+3.13\;{\pm}\;2.73$, AAM: $+2.25\;{\pm}\;2.93$) and elasticity level (AM: $+5.81\;{\pm}\;8.27$, AAM: $+5.50\;{\pm}\;6.13$) of AM (p < 0.001) and AAM (p < 0.05) were increased. The facial evenness level (AM: $-5.25\;{\pm}\;8.13$, AAM: $-9.17\;{\pm}\;4.26$) and wrinkle level (AM: $-10.88\;{\pm}\;11.74$, AAM: $-17.83\;{\pm}\;12.22$) were significantly decreased. AAM was more effective in improving skin elasticity, evenness, and wrinkle. The skin status of PM was not changed. While the macronutrient intakes of all the subjects were not different before and after the study, the daily intakes of some vitamins (vitamins $B_6$, C, and E and folic acid) during the study were significantly increased in AAM. These findings suggested that regular use of apple mask pack was effective in improving overall skin status. Furthermore, the consumption of apples with mask pack application was much better in improving skin status.

• Journal of the Korea Society of Computer and Information
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• v.27 no.11
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• pp.219-229
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• 2022

This study is to evaluate the intervention effect using a flowmeter in bag-valve mask skill education. The purpose of this study was to compare the accuracy of bag-valve mask skill between intervention group with flowmeter and control group without flowmeter, understand the improvement effect of skill education of bag-valve mask, and provide basic data to suggest the method of skill education. The total number of subjects of this study was 60, with 30 intervention group and 30 control group. In comparison of the optimal number of normal tidal volume range at pre-test and post-test, the normal range percentages of the intervention group before and after education were 32.8% and 86.7%, respectively, and there was a significant difference(p<0.01). The normal range percentages of the control group before and after education were 20.0% and 34.7%, respectively, and there was a significant difference(p<0.05). To evaluate the factors associated with good performance of bag-valve mask skill of the subjects including the normal range of tidal volume, the logistic regression analysis has been performed, and the significant influential factors were gender(10.305, 1.20-87.98), educational experience of field practice(31.674, 1.25-805.16), and intervention(92.750, 4.58-1879.69). Through this study, it was confirmed that the intervention using flowmeter for the skill education of bag-valve mask was effective, and it is necessary to consider reflecting it in the education of students majoring in emergency medical technology in the future.

• Journal of the Health Care and Life Science
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• v.8 no.2
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• pp.181-189
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• 2020

This study conducted a questionnaire survey using the Google questionnaire on 285 college students over 20 years old who attended universities in Chungnam to investigate the personal quarantine attitude of college students according to COVID-19. As a result, the attitude of washing hands, coughing etiquette, wearing a mask, and keeping distance under running water for more than 30 seconds scored high. However, when the mask was removed, the method of storing the mask or disinfecting surrounding objects such as desks at school was insufficient. Therefore, the attitude of personal quarantine should be more emphasized in the national quarantine system as a basic policy for preventing the spread of COVID-19 in the future and ending the virus.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.4
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• pp.395-402
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• 2023

Objectives: Microbial contamination of face masks used by healthcare professionals can vary depending on the degree of exposure to bioaerosols in various healthcare environments. However, research on this topic is limited. Therefore, we analyzed microbial contamination of N95 respirators used in hospital offices, wards, and outpatient settings. Methods: Samples isolated from N95 respirators worn for 2, 4, and 6 hours were incubated at a temperature of 35-37℃ or 25-28℃ for 24 hours or for 3-7 days, and colony-forming units were counted in chocolate agar, tryptic soy agar, and Sabouraud dextrose agar plates. Total indoor airborne bacteria were also measured in the healthcare environments. Finally, microbial species were identified using Gram staining with a microscopic speculum. Results: The three types of environments did not deviate from the maintenance of standard indoor air quality. There was no difference between the microbial species identified in the healthcare environment and mask contamination. However, the number of bacteria in the masks worn in each environment differed, and the degree of contamination increased with mask-wearing time (p<0.05). Conclusions: Therefore, care must be taken to avoid recontamination of masks due to improper use and exposure to biological hazards in healthcare environments. In conclusion, scientific evidence is necessary for safe mask-wearing times. Based on the results of this study, we hope to conduct further research to establish guidelines for the safe use of face masks during respiratory disease epidemics.

• Journal of Ginseng Research
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• v.47 no.2
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• pp.169-172
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• 2023

The coronavirus disease 2019 (COVID) pandemic began in December 2019. Many countries have implemented restrictions such as mandatory mask wearing and social distancing. These measures have caused diverse and complex health problems, particularly in women's health, anxiety, and depression. This review examines an alternative approach to the treatment of endometriosis during the COVID pandemic. The efficacy of ginseng with anti-inflammatory activity and ability to relieve or prevent symptoms of endometriosis is discussed and reviewed.

• The Korean Journal of Health Service Management
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• v.7 no.3
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• pp.193-202
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• 2013

This study aimed to investigate and compare the perception of personal protective equipments and instrument sterilization of students who are in attendance at colleges and universities and which have bedside training as a regular subject in their curriculum for third-year students. 'Completely True' is the highest response to the question about the importance of wearing gloves, mask and medical gown from all groups. 'Completely True' is the highest response to the question about the necessity for replacement of gloves from all groups. 'Moderate True' is the highest response to the question about the necessity for replacement of mask from the group without practical training and 'Completely True' is the highest response to the question about the importance of hair cleanliness from all groups regardless of practical training experience. For the question about the perception of instrument disinfection and sterilization, the group with inside and outside practical training showed the highest perception level. Consequently, the right education for prevention of infection by setting inclusive guidelines to enhance the level of perception and practice seems continuously necessary.