• 구강회복응용과학지
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• 제23권4호
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• pp.359-371
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• 2007

Recently, many studies were reported accurate analysis of facemask effect due to the development of the personal computers and computer programs. The aim of this study is appropriate protraction direction of facemask using finite element study with computer aided design and computer aided measurement. The construction of the three dimensional FEM was based on the computer tomography(CT) scans of 13.5 year-old male subject. Protraction force of 500 mg was applied at 0, 30, 60 and 90 degrees downwards to the Frankfort horizontal plane, and maxillary displacement and stress distribution were measured. When 60 degree force was applied, it showed forward movement of premolar roots area and downward movement of anterior nasomaxillary area, and others showed clockwise rotation movement of the nasomaxillary complex. Finally, we can produce the protraction of maxillary bone without rotation of maxilla about 60 degrees.

• 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.

• 한국산업보건학회지
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• 제34권1호
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• pp.48-56
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• 2024

Objectives: The coronavirus pandemic that began in 2019(COVID-19) has been one of the worst pandemics of the 21st century. Masks have been used to prevent COVID-19, but there are currently no standards for the long-term use of masks in the Republic of Korea. This study was conducted to assess the microbiological safety of KF94(Korea Filter 94) disposable face masks according to wearing duration by evaluating the bacterial filtration efficiencies of masks worn by research participants. Methods: A commercially available KF94 mask certified by the Ministry of Food and Drug Safety(MFDS) in the Republic of Korea was selected as the test mask. The research participants(n = 15) wore masks for the durations of one, three, and seven days. Participants also reported several parameters, including wearing time, makeup frequency, and storage. Bacterial filtration efficiencies of the worn masks were measured by a mask bioaerosol filtration tester. Staphylococcus aureus(S. aureus) was used as the test bacteria and quantitatively measured through the cultivation method. Then, bacterial filtration efficiency was calculated using the formula suggested by the MFDS. Results: All worn masks showed over 99.98% of mean bacterial filtration efficiency for S. aureus. There were no significant differences among bacterial filtration efficiencies of face masks according to wearing duration. There was also no significant difference among bacterial filtration efficiencies among participants. There was no correlation between the results of bacterial filtration efficiencies and reported parameters from participants. Conclusions: In the absence of significant external damage to the mask, the bacterial filtration efficiency of the mask can be maintained even after seven days of wearing. This result suggests that KF94 masks certified by the MFDS can be used repeatedly for about a week without loss of bacterial filtration efficiency.

• 한국인터넷방송통신학회논문지
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• 제8권1호
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• pp.25-30
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• 2008

본 논문에서는 인물 이미지를 GIF로 변환 할 시에 색상의 손실을 최대한 줄이기 위한 알고리듬을 제안한다. 손실을 줄이는 방법으로는 Octree Quantization과 살색 검출 mask를 이용한다. 인물이미지의 경우, 살색정보가 이미지의 중요한 부분을 차지하고 있으므로, 살색 영역을 검출 할 수 있는 mask를 생성하여 살색영역과 그 밖의 영역을 분리하고, 분리된 영역별로 Color Quantization을 한다. 제안된 알고리듬을 통하여 24비트 이미지를 GIF로 변환한 결과, 일반적으로 많이 사용하는 이미지 포맷변환 툴을 사용하여 변환한 영상보다 살색 정보의 손실이 최소화됨으로써, 인물이미지의 GIF 변환에 있어 좋은 성능을 보여 준다는 것을 확인할 수 있다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 추계학술대회
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• pp.303-304
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• 2021

코로나 방역을 위해 마스크 착용 여부를 자동으로 감지하는 것은 중요한 이슈이다. 기계학습을 통하여 얼굴의 마스크 착용여부를 검색하는 것은 마스크를 착용한 얼굴 데이터를 학습함으로써 해결할 수 있는 것으로 알려져 있다. 하지만 한 사람을 위한 마스크 착용 여부 검색은 OpenCV를 이용하여 보다 간단한 방법으로 감지할 수 있다. 본 논문에서는 OpenCV 학습데이터 결과와 간단한 함수들을 이용하여, 범용 PC 카메라로 한 사람의 마스크 착용여부를 쉽게 감지할 수 있음을 기술한다. 실험을 통하여 제안하는 방법이 유효함을 보였다.

• 대한치과의사협회지
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• 제41권10호통권413호
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• pp.720-727
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• 2003

Clinicians generally agree that Class III malocclusion is one of the most difficult to treat. When the Class III malocclusion is characterized by maxillary retrusion in growing patients, the use of a face mask may be the treatment of choice. Although face mask can achieve excellent orthopedic effects. It demands special patient compliance because it is worn extraorally and is not as esthetic or comfortable as intraoral appliance. This report presents the clinical cases of mandibular protrusion correction in growing patients, who were treated by TTBA(Tandem Traction Bow Appliance) that's a intraoral appliance.

• 대한치과교정학회지
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• 제53권1호
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• pp.54-64
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• 2023

This case report describes skeletal anchorage-supported maxillary protraction performed with the Alternate Rapid Maxillary Expansion and Constriction (AltRAMEC) protocol over a treatment duration of 14 months in a 16-year-old female patient who was in the late growth-development period. Miniplates were applied to the patient's aperture piriformis area to apply force from the protraction appliance. After 9 weeks of following the Alt-RAMEC protocol, miniplates were used to transfer a unilateral 500-g protraction force to a Petit-type face mask. A significant improvement was observed in the soft tissue profile in measurements made both cephalometrically and in three dimensional photographs. Subsequently, the second phase of fixed orthodontic treatment was started and the treatment was completed with the retention phase. Following treatment completion, occlusion, smile esthetics, and soft tissue profile improved significantly in response to orthopedic and orthodontic treatment.

• 디지털융복합연구
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• 제16권12호
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• pp.571-577
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• 2018

자전거 이용자가 안경 및 선글라스를 쓴 상태에서 마스크를 착용 할 때 여러 가지 불편함을 호소한다. 본 논문은 이러한 불편함을 보완하여 자전거 라이더들에게 필요한 일회용 미세먼지 마스크를 개발하는데 그 목적이 있다. 미세먼지 마스크의 특성상 일회성 정전기 발생 섬유와 마스크의 형태적 문제로 연구범위를 제한하고 기존 미세먼지 마스크를 간결한 제작공정으로 디자인한다. 이렇게 개발된 일회용 미세먼지 마스크는 세로방향 접힘으로 입 앞 마스크 내 공간을 충분히 확보하였고 거친 숨에도 입에 닿지 않게 접힘 부위형태가 유지 되게 하여 답답함을 최소화 하였다. 코지지대에 유선형 스폰지를 부착하고 안면 볼 부위를 일반마스크 보다 2.5cm 정도의 확장하여 측면 밀착성을 높였다. 또한 기존에 없던 일회용 미세먼지 스카프 마스크를 제작하여 안면과 목 부위 자외선을 차단하고 밀착성 높은 미세먼지 마스크를 개발하였다.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 1999년도 춘계학술대회 논문집
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• pp.38-40
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• 1999

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 추계학술대회
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• pp.167-170
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• 2010

본 논문에서는 프로젝션 함수와 허프 변환을 이용하여 영상에서 눈동자를 찾는 방법을 제안한다. 먼저, 영상으로부터 얼굴영역을 추출한 다음, 눈썹과 눈동자의 밝기변화의 특징을 이용할 수 있는 integral projection function과 variance projection function을 사용하여 눈 영역을 검출한다. 검출된 눈 영역에서 눈동자 중심좌표를 구하기 위해 원형 허프 변환을 이용한다. 원형 허프 변환에 사용된 좌표는 sobel edge mask를 사용하여 구한다. FERET database의 정면 얼굴 영상을 이용하여 제안된 방법으로 실험한 결과 만족할 만한 결과가 나왔다.