• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.3
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• pp.179-188
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• 2024

Objectives: The safety of distributed masks has been widely investigated following the coronavirus disease (COVID-19) pandemic. Although the unpleasant odor from masks is concerning, research on the toxicity of volatile organic compounds emitted from them is limited. Here, we aimed to quantify the VOCs emitted from masks and explore strategies for safe mask usage. Methods: The VOCs emitted from 15 masks in five categories were measured. Proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS, IONICON, Austria), which can rapidly and sensitively detect complex mixtures, was conducted. The test chamber connected to the equipment was comprised of uninterrupted acrylic and glass. PTR-TOF-MS data were analyzed using Tofware (PTR-MS Viewer 3.3, IONICON, Austria). Statistical analyses were performed using SPSS ver. 20 to determine the highest, lowest, and average concentrations of the VOCs (IBM SPSS Inc., USA). Analysis of variance (ANOVA) was conducted to compare the VOCs emitted from different masks. Results: A total of 25 VOCs were detected among the 15 masks. The peak concentrations of formaldehyde, acrolein, isoprene, and benzene were higher than the exposure standards (Ceiling). The average concentrations of these compounds differed significantly among the mask samples (p < 0.05). The VOC concentration decreased gradually after approximately one hour. Conclusions: Higher concentrations of VOCs were emitted from healthy, printed, and surgical masks compared to industrial masks. Further research is required to determine the factors affecting VOCs, such as mask material, temperature, and humidity. For safety, masks must be ventilated for at least an hour before usage.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.452-457
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• 2011

The internal temperature of an operating room had to keep within $20^{\circ}C$. However, the doctor who is wearing operating gown and mask caused to rise temperature because of the thermal occurrence of dental LED light source. At first, the surgery environment is getting worse. And then last, it would increase bleeding rate by the expansion of patient's exposured blood vessel. A surgical operator can distribute the patient's tissue through such surgery environment, exactly. It can do accurate surgery. So, it gave to effect that surgical operator's eye condition is getting better and it could keep a mutual assistance system. For this research, we develop the LED dental light source module of high color rendition. It performed simulation for replacing established the method of Halogen lamp and Plazma lamp of light source. We analyzed intensity of illumination and the change of viability by changing the height of light source module.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.109-123
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• 2020

Objectives: The aims of this study were to review the standards and key components of the standards for disposable masks in Korea, the US, EU, Japan, and China and to evaluate the appropriateness of disposable masks during a virus pandemic. Methods: We reviewed the standards in the above countries and compared their key elements for each standard. For the second purpose, systemic paper gathering using key words like 'mask', 'respirator' 'virus', and 'coronavirus' in the PubMed search engine was performed. Fifty-three papers were selected and reviewed in regard to the appropriateness of test protocols with sodium chloride(NaCl) particles for virus filtration and the effectiveness against viruses. Results: The standards for masks are largely divided into two categories: US standards and EU standards. In Korea, the Ministry of Employment and Labor adapted the EU standards for workers and the Health Masks adopted the Ministry of Employment and Labor standards by the Ministry of Food and Drug Safety. Regarding airborne viral infections, WHO emphasizes only droplet infection, while many studies have shown that small particles enter the air through coughing or sneezing, which increases the possibility of airborne infection. Compared to other particles, various factors such as airborne viability and the ability to replicate the virus in the body are further involved in the virus's airborne infection rate. Airborne infection is classified into absolute air infection, preferential air infection, and opportunistic air infection. The NaCl-certified N95 mask showed good filtration efficiency against viruses and NaCl particles were proved to be a surrogate material for viruses. From this, KF94 is also expected to be effective in blocking viruses. Conclusion: The N95 test method could be used as a surrogate test method for virus filtration. N95-class masks have been found to effectively block viral infections in the air. However, surgical or medical masks are only partially effective against airborne virus infection though they could effectively block large droplet infection. However, most studies considered in this study targeted N95 in foreign countries and studies on masks actually used in Korea are very limited, so studies on microorganisms and reuse on domestic masks should be conducted in the future.

• Korean Journal of Cleft Lip And Palate
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• v.11 no.1
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• pp.37-48
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• 2008

Cleft lip and palate patients often develop maxillary retrusion due to the combined effects of the congenital deformity and the scar tissue after surgical repairs. Maxillary protraction in the cleft patients using orthopedic appliances (i.e. face mask) or distraction osteogenesis during early childhood helps to achieve more balanced skeletal harmony and favorable occlusion for future growth to occur. Kinds, indication, protocol for use of the traditional orthopedic appliances will be discussed. Also the facemask with miniplate system recently developed will be introduced.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.4
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• pp.859-866
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• 1996

It is a relatively rare clinical experience to see the impacted first molar. The first permanent molar is the key in normal occlusion. Abnormal eruption of the first permanent molars would inflict normal development of dental arches and give rise to abnormal root resorption of the adjacent teeth. Therefore, the abnormally erupted first permanent molars should be detected and treated early in order to obtain proper occlusal guidance in mixed dentition period. This report presents two cases on distally tilted and impacted mandibular first molars which were treated by surgical exposure and orthodontic traction using facial mask.

• Archives of Plastic Surgery
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• v.50 no.2
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• pp.220-221
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• 2023

Microsurgical peripheral nerve repair is a technical and challenging procedure that requires thorough training prior to a real-life operating theater scenario. While the gold standard in training remains training on biological living peripheral nerve specimen, various inanimate models of nerve repair simulation have been described in the past years. The textile elastic band (TEB) obtained from a surgical mask was either covered with a fine silicone sheath or was left bare and was used afterward for end-to-end coaptation. The average diameter of the TEB was 2 mm, similar with the nerves in the distal hand and can be easily crafted out of accessiblematerials such as a surgicalmask and silicone sealant. The silicone that covers the TEB offers more fidelity to the simulation for microsurgical nerve coaptation. The TEB model offers an affordable, available, and easy-to-craft alternative to the existing models for peripheral nerve repair simulation and serves as a good initiation tool before moving on to biological specimens.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.1
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• pp.53-60
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• 2009

Maxillary deficiency, anterior cross bite, constriction of maxillary arch, malaligned teeth are frequently observed in patients with cleft lip and palate. Surgery and orthodontics, combined intervention are needed to correct maxillary deficiency. Distraction osteogenesis that currently used has many advantages like less relapse tendency, more advancement of maxilla, capable in growing patients. In case 1, 18 years old girl with BCLP had severe midfacial deficiency and multiple missing of teeth. LeFort I osteotomy, followed by maxillary distraction osteogenesis utilizing rigid external distraction device(RED) system, was performed. After a 6-day latency period, distraction proceeded at a rate of 1mm per day (at 1st week, 1.5mm/day). Total advancement was 19mm. The RED device left in place for the additional 4 weeks for consolidation. After the RED device was removed, face mask was applied with elastic traction for 5 weeks. After achieving acceptable facial appearance and occlusion, orthodontic appliance was removed. The results after 4 years follow-up was sustained pretty well without aggravation of velopharyngeal function. In case 2, 22 years old man with UCLP had severe midfacial deficiency and palatally erupted upper 2nd premolars due to arch length discrepancy, but the anterior segment of maxillary did not show constriction and crowding. patient had no arch width discrepancy, crowding was concentrated on premolar region. Segmental LeFort I osteotomy was performed. After a 6 - day latency period, using internal distraction device, distraction proceeded at a 0.5mm per day(at 1st week, 0.75 - 1 mm/day). Total advancement was 15mm. After internal distraction device was removed, face mask was applied with elastic traction for 4 weeks. After surgical-orthodontic treatment, facial appearance and occlusion was improved pretty good, and after 46 months follow-up the result was retained well.

• The Journal of the Convergence on Culture Technology
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• v.3 no.2
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• pp.15-20
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• 2017

We are investigated about the Hepatitis infection risk of the funeral director related to wearing PPE(Personal Protect Equipment) within Metropolitan, Chungcheong and Gyeongsang regions in Korea. We are classified that the vaccinated group was classified as low risk group and the non-vaccinated group was classified as high risk group. And we are analyzed the risk rate of infection based on whether or not to wear PPE(personal protective equipment) among high-risk groups. The result is as follows. The mask wearing rate of high-risk group about HAV(hepatitis A virus) is three times lower than that of low-risk group. The surgical glove wearing rate of high-risk group about HBV(hepatitis B virus) is twice lower than that of low-risk group. The surgical glove and mask not wearing rate among the high-risk group observe that potential infection risk was high 4.23 times and 3.5 times, respectively. We are concluded that increasing the risk of potential infection risks from the funeral director could result in increased risk of infection to national public health, including the bereaved family. We are suggested that the funeral director must be bound to vaccinate against hepatitis and make PPE mandatory. It is deemed necessary for the government to develop policies to promote personal health and national health care.

• The Journal of the Korean dental association
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• v.49 no.4
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• pp.219-226
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• 2011

Snoring and obstructive sleep apnea (OSA) are common sleep disordered breathing conditions. Habitual snoring is caused by a vibration of soft tissue of upper airway while breath in sleeping, and obstructive sleep apnea is caused by the repeated obstructions of airflow for a sleeping, specially airflow of pharynx. Researchers have shown that snoring is the most important symptom connected with the obstructive sleep apnea syndrome The treatment is directed toward improving the air flow by various surgical and nonsurgical methods. The current surgical procedures used are uvulopalatopharyngoplasty(UPPP), orthognathic surgery, nasal cavity surgery. Among the nonsurgical methods there are nasal continuous positive air pressure(CPAP), pharmacologic therapy. weight loss in obese patient, oral appliance(sleep splint). Sleep splint brings the mandible forward in order to increase upper airway volume and prevents total upper airway collapse during sleep. However, the precise mechanism of action is not yet completely understood, especially aerodynamic factor. The aim of this study evaluated the effect of conservative treatment of snoring and OSAS by sleep splint through measured aerodynamic change by an aerophone II. We measured a airflow, sound pressure level, duration, mean power from overall airflow by aerophone II mask. The results indicated that on a positive correlation between a decrease in maximum airflow rate and a decrease in maximum sound pressure level, on a negative correlation between a decrease in maximum airflow rate and a increase in duration.

• The korean journal of orthodontics
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• v.50 no.5
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• pp.346-355
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• 2020

The treatment of skeletal Class III malocclusion in adolescents is challenging. Maxillary protraction, particularly that using bone anchorage, has been proven to be an effective method for the stimulation of maxillary growth. However, the conventional procedure, which involves the surgical implantation of mini-plates, is traumatic and associated with a high risk. Three-dimensional (3D) digital technology offers the possibility of individualized treatment. Customized mini-plates can be designed according to the shape of the maxillary surface and the positions of the roots on cone-beam computed tomography scans; this reduces both the surgical risk and patient trauma. Here we report a case involving a 12-year-old adolescent girl with skeletal Class III malocclusion and midface deficiency that was treated in two phases. In phase 1, rapid maxillary expansion and protraction were performed using 3D-printed mini-plates for anchorage. The mini-plates exhibited better adaptation to the bone contour, and titanium screw implantation was safer because of the customized design. The orthopedic force applied to each mini-plate was approximately 400-500 g, and the plates remained stable during the maxillary protraction process, which exhibited efficacious orthopedic effects and significantly improved the facial profile and esthetics. In phase 2, fixed appliances were used for alignment and leveling of the maxillary and mandibular dentitions. The complete two-phase treatment lasted for 24 months. After 48 months of retention, the treatment outcomes remained stable.