• 한국환경보건학회지
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• 제30권5호
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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.

• 대한치과기공학회지
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• 제33권1호
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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.

• 한국환경보건학회지
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• 제41권3호
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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.

• 한국방사선학회논문지
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• 제15권1호
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• pp.21-28
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• 2021

전산화단층촬영장치 (computed tomography, CT)는 다른 방사선 촬영 장치와 비교하면 피폭이 많다는 문제점이 있다. 이러한 피폭을 감소하기 위하여 저선량 촬영을 하게 되면 영상에 잡음이 증가하게 된다. 이를 보완하기 위해 환자의 피폭선량은 감소시키면서 영상의 화질을 향상하는 다양한 잡음 제거 알고리즘이 개발되었으며, 그 중 우수한 시간 분해능을 가진 CT 장치에 효과적으로 적용할 수 있는 median modified Wiener filter (MMWF) 알고리즘이 제시되었다. 본 연구의 목적은 MMWF 알고리즘의 마스크 크기를 최적화하고, 기존의 알고리즘들에 대한 MMWF 알고리즘의 잡음 제거의 우수성을 보는 것이다. MATLAB 프로그램을 이용하여 획득한 Gaussian 잡음이 부가된 MASH 팬텀 복부 영상들로부터 각각의 마스크 크기가 설정된 MMWF 알고리즘을 적용한 후 root mean square error (RMSE), peak signal-to-noise ratio (PSNR), coefficient correlation (CC) 그리고 universal image quality index (UQI) 값을 비교하였다. 그 결과 5 × 5 마스크 크기에서 RMSE 값이 가장 낮고, PSNR, CC, UQI 값이 가장 높았다는 것을 확인할 수 있었다. 또한, 최적화된 마스크 크기로 Gaussian 필터, median 필터, Wiener 필터에 대한 MMWF의 RMSE, PSNR, CC, UQI 값을 비교하였으며 그 결과 MMWF 알고리즘에서 가장 개선된 RMSE, PSNR, CC, UQI 값을 얻을 수 있었다.

• 정신신체의학
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• 제32권1호
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• pp.10-23
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• 2024

본 연구는 코로나19 팬데믹 동안 마스크 착용자에 대한 매력도와 사회적 인식 변화를 고찰한다. 코로나19 이전에는 마스크가 감염 신호로 여겨져 매력도를 감소시켰으나, 팬데믹 이후 마스크 착용이 일상화되면서 인식 메커니즘이 복잡해졌다. 마스크 착용자에 대한 매력도와 사회적 인식은 착용자의 기본 매력도, 인종, 마스크에 대한 인식 등에 따라 달라진다. 이로 인해 연구 결과가 일관되지 않다. 이는 실험 방법의 불일치와 피험자 개인차를 고려하지 못한 결과다. 정신의학적 관점에서 팬데믹 상황에서의 매력 인식을 연구하기 위해서는 행동면역계와 관련된 심리적 메커니즘을 중심으로 새로운 가설을 수립하고 검증해야 한다. 이는 대인 지각과 혐오가 정신건강에 미치는 영향을 이해하는 데 중요한 단서를 제공할 수 있다.

• Journal of Nutrition and Health
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• 제43권5호
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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.

• 한국컴퓨터정보학회논문지
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• 제27권11호
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• pp.219-229
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• 2022

본 연구는 백-밸브마스크 술기교육에 호흡량측정기를 활용한 중재 효과를 평가하기 위한 연구이다. 본 연구의 목적은 호흡량측정기를 적용한 중재군과 적용하지 않은 대조군의 백-밸브마스크 술기의 정확도를 비교하여 호흡량측정기를 활용한 백-밸브마스크 술기교육에 의한 일회 환기량 제공 개선 효과를 파악하여 술기교육 방안을 모색하기 위한 기초자료를 마련하고자 실시하였다. 중재군 30명, 대조군 30명으로 총 60명을 대상으로 한 본 연구에서 교육 전·후 일회환기량 정상범위 대상자 수를 비교하면 중재군의 정상범위 백분율은 교육 전 32.8%, 교육 후 86.7% 이었으며, 유의한 차이가 있었다(p<0.01). 대조군도 교육 전 20.0%, 교육 후 34.7% 이었으며, 유의한 차이가 있었다(p<0.05). 일회환기량 정상범위 포함 횟수의 영향요인을 알아보기 위해 로지스틱 회귀분석을 실시한 결과, 성별(10.305, 1.20-87.98), 소방실습경험(31.674, 1.25-805.16), 중재여부(92.750, 4.58-1879.69)가 유의한 영향 요인이었다. 이 연구를 통해 백-밸브마스크를 이용한 교육에 호흡량측정기를 활용한 중재가 효과적이었다는 것을 확인할 수 있었으며, 향후 응급구조(학)과 전공 학생 교육에 반영할 것을 검토할 필요가 있다.

• 보건의료생명과학 논문지
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• 제8권2호
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• pp.181-189
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• 2020

본 연구는 코로나19에 따른 대학생의 개인방역태도를 조사하기 위하여 충남 소재 대학교에 등교하는 20세 이상 대학생 285명을 대상으로 구굴 설문을 이용한 설문조사를 하였다. 그 결과 30초 이상 흐르는 물에 손씻기, 기침예절, 마스크 착용, 거리두기의 태도는 높은 점수를 얻었다. 그러나 마스크를 벗을 시 마스크 보관 방법이나 학교에서의 책상 등 주변 사물의 소독하는 방역태도는 미흡하였다. 따라서 개인방역태도는 앞으로의 코로나19의 확산을 막고 더 나아가 바이러스의 종식을 위한 기본적인 방침으로 국가의 방역시스템체계 속에서 더욱 강조되어야 할 것이다.

• 한국산업보건학회지
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• 제33권4호
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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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• 제47권2호
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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.