• Journal of the Korean Society of Safety
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• v.5 no.3
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• pp.3-7
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• 1990

This study is conducted to experiment on the performance test for 20 types of Filter-integrated Half-masks which could not only protect workers exposed to dusty environment, but also improve workability. Results and conclusions are as follows ： 1) Respirators that removal efficiency of aerosols is 95 percent or more are 11 kinds(55%), and those who are 99.9 percent or more are 4 kinds(20%). Respirators that inhalation resistance is 4 mm in water or less are 13 kinds(65%), and those who are 6 mm in water or less are 17 kinds(85%). Respirators that efficiency of cumulative inhalation resistance is 100 percent or less are 11 kinds(55%) . 2) Respirators that resistance of moisture inhalation is 6 mm in water or less are 11 kinds(55%). and those who are 10 mm in water or less are 13 kinds(65cio), Respira'tors that ratio of removal efficiency for aerosols between dry and wet conditions is 95 percent or more are 9 kinds(45%). 3) Respirators which are not only 95 percent or more for removal efficiency of aersosls and 6 mm in water or less for inhalation resistance, but also 200 percent or less for efficiency of cumulative inhalation resistance, are 8 kinds(40％). Respirators which are not only 99.9 percent or more for removal efficiency and 6 mm in water or less for inhalation resistance, but also 100 percent or less for efficiency of cumulative inhalation resistance, are 3 kinds(15%). Respirators which are not only 95 percent or more for removal efficiency of aerosols and 6 mm in water or less for inhalation resistance, but also 200 percent or less for efficiency of cumulative inhalation resistance and 10 mm in water or less for resistance of moisture inhalation, are 6 kinds(30％) . 4) As standard rrlodel of artificial human head which would be perhaps different from the true one Is used to experiment fitness test, leakage rate is shown to be more or less high. However, artificial human head shall be accurately examined and follow-up studt. would be conducted in the future.

• Journal of Environmental Health Sciences
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• v.47 no.3
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• pp.292-301
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• 2021

Objectives: Wearing medical masks has been recommended since the declaration of coronavirus disease-19 (COVID-19) as a pandemic disease. Certified medical masks are evaluated according to filtration efficiency and facial inhalation resistance. However, some people use non-certified common masks. This study aimed to evaluate various non-certified commercial masks based on the certification criteria for medical masks. Methods: Twenty mask products (three anti-droplet, three disposable dental, eight fashion, three cotton, and three children's masks) were selected. For performance evaluation, filtration efficiency and facial inhalation resistance tests were conducted. The evaluation method followed the certification method for KF-certified masks of the Ministry of Food and Drug Safety (MFDS) and the N95 respirator of the National Institute for Occupational Safety and Health (NIOSH). Results: None of the 20 masks met the KF94 certification standard set by the MFDS. Four and three masks respectively met the KF80 certification standard and the N95 standard of NIOSH. Filtration efficiency was significantly higher in three-layer masks than in single layer masks. Pleated-type masks had higher filtration efficiency than cone-type masks. There was no correlation between the structure of masks and facial inhalation resistance. Conclusion: While no masks complied with the KF94 certification standard, a few masks met the KF80 and the N95 certification standards of NIOSH. Although some people wear non-certified commercial masks, protection from aerosols is not guaranteed by such masks. Evaluation of the protection efficiency of non-certified mask against microbiological infection is needed for the prevention of infectious disease.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.1
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• pp.53-63
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• 2022

Objectives: This study was designed to evaluate the filtration efficiency, inhalation resistance, and liquid resistance of commercial reusable masks in comparison to the performance of KF-AD masks (reference masks). Methods: Thirty-six masks were purchased from an online market. Filtration efficiency and inhalation resistance were determined in the same manner as in MFDS certification testing, respectively using TIL/IL & Filter Test 1300S (SFP Services, UK) and Breathing Resistance Analyzer DA2001 (Lambda Ray, South Korea). Results: Most of the filtration efficiencies found for the 19 masks were far lower than the test standard for KF-certified masks. Four masks met KF94 and three masks even met KF80. Most inhalation resistances were also much lower than the standard, with many almost one-half of the standard. In addition, all the masks except KF-AD masks did not pass the liquid resistance test. Conclusions: Although most of the filtration efficiency performance results found in this study for the reusable masks, which emerged as an alternative, were lower than the standard for health masks, multi-use masks can be used with a replacement filter inserted.

• PNF and Movement
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• v.18 no.2
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• pp.297-303
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• 2020

Purpose: The purpose of this study was to examine the effects of inhalation and exhalation exercise combined with upper extremity proprioceptive neuromuscular facilitation pattern on two spirometry values: forced volume vital (FVC) and peak expiratory flow (PEF). Methods: Thirty-two healthy adults were divided into two groups: 1) a combined group, which performed upper extremity D2 flexion pattern (shoulder flexed/abducted/external rotated, forearm supinated, wrist radial deviated, and finger extended) during exhalation and D2 extension pattern (shoulder extended/adducted/internal rotated, forearm pronated, wrist ulnar deviated, and finger flexed) during inhalation; and 2) reverse combined group, which performed the D2 flexion pattern during inhalation and the D2 extension pattern during exhalation. The inverse application of upper extremity movements during inhalation and exhalation induced selective resistance or assistance on respiration. FVC and PEF were measured at two time points, before and after four weeks. Results: In both groups, the pre-post intervention comparison showed significant increases in FVC and PEF (p < .05). In the between-groups comparison, the reverse combined group showed a significantly higher PEF than the combined group at four weeks post intervention (p < 0.05). Conclusion: The combined respiration exercise with reverse PNF upper extremity patterns using selective resistance showed an effective increase in PEF in healthy adults. Clinicians and researchers might consider using selective resistance as a widely applicable and cost-effective option for respiratory rehabilitation planning.

• Fashion & Textile Research Journal
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• v.23 no.3
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• pp.406-414
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• 2021

This study aimed to evaluate the inhalation resistance(IR) and fiber structure of disposable masks when exposed to repeated heating and ultraviolet(UV) sterilization. The experiments consisted of a lab-scale and a field test. For the lab-scale test, KF94 and N95 masks were selected and a trial was composed of three repetitions of an 80-min sterilization. For the field test, a subject participated over four days, of which a KF94 was worn without sterilization, and the same trial was conducted during the next four days with daily sterilization. The results showed that the IR of the KF94 mask(9.5 Pa) gradually increased according to the sterilization up to the second repetition(15.6 Pa) but decreased at the third treatment(9.7 Pa). However, the N95 mask did not showany tendency of IR during the repetitions. Microscope photos showed several warped or blackened fibers in the stiffener layer after the repeated sterilization. After wearing a KF94 mask for four consecutive days, its IR decreased until the three days but increased the fourth day, whereas another KF94 mask with sterilization showed an increase in IR for the four days. In the microscope-photos after the consecutive four days, outside fibers and stiffener layers were warped or became less dense. In summary, the IR of the KF94 mask slightly increased through the three~four rounds of heating and UV sterilizations, but the fiber structures were not significantly deformed by the repeated sterilization. To reduce discarded mask waste, the repeated sterilization of masks can be recommended.

• Tuberculosis and Respiratory Diseases
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• v.52 no.3
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• pp.251-259
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• 2002

Background : Reduced lung compliance and increased lung resistance are the primary lung mechanical abnormalities in acute respiratory distress syndrome (ARDS). Although there is little information regarding the mechanisms responsible for the increases in the respiratory resistance of ARDS, bronchodilators have been frequently administered in mechanically ventilated ARDS patients. To determine the effect of a bronchodilator on the respiratory mechanics depending on the level of applied positive end-expiratory pressure (PEEP), the changes in the respiratory mechanics by salbutamol inhalation was measured under the variable PEEP level in patients with ARDS. Materials and Methods : Fifteen mechanically ventilated paralyzed ARDS patients (14 of male, mean age 57 years) were enrolled in this study. The respiratory system compliance, and the maximum and minimum inspiratory resistance were obtained by the end-inspiratory occlusion method during constant flow inflation using the CP-100 pulmonary monitor (Bicore, Irvine, CA, USA). The measurements were performed at randomly applied 8, 10 and 12 cm $H_2O$ PEEP before and 30 mins after administrating salbutamol using a meter-dose-inhaler (100ug${\times}$6). Results : 1) The maximum inspiratory resistance of the lung was higher than the reported normal values due to an increase in the minimal inspiratory resistance & additional resistance. 2) The maximum inspiratory resistance and peak airway pressure were significantly higher at 12cm $H_2O$ of PEEP compared with those at 10cm $H_2O$ of PEEP. 3) Salbutamol induced a significant decrease in the maximum and the minimum inspiratory resistance but no significant change in the additional resistance only was observed at 12cm $H_2O$ of PEEP(from $15.66{\pm}1.99$ to $13.54{\pm}2.41$, from $10.24{\pm}2.98$ to $8.04{\pm}2.34$, and from $5.42{\pm}3.41$ to $5.50{\pm}3.58cm$ $H_2O$/L/sec, respectively). 4)The lung compliance did not change at the applied PEEP and salbutamol inhalation levels. Conclusion : The bronchodilator response would be different depending on the level of applied PEEP despite the increased respiratory resistance in patients with ARDS.

• Clinical and Experimental Pediatrics
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• v.57 no.10
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• pp.461-463
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• 2014

Decreased exercise capacity after Fontan surgery is relatively common and the failure of the Fontan state gradually increases with age. However, there is no further treatment for patients with Fontan circulation. Pulmonary vasodilation therapy is an effective method to solve this problem because pulmonary vascular resistance is a major factor of the Fontan problem. Inhaled iloprost is a chemically stable prostacyclin analogue and a potent pulmonary vasodilator. We experienced two cases of Fontan patients treated with inhaled iloprost for 12 weeks. The first patient was an 18-year-old female with pulmonary atresia with an intact ventricular septum, and the second patient was a 22-year-old male with a double outlet right ventricle. Fifteen years have passed since both patients received Fontan surgery. While the pulmonary pressure was not decreased significantly, improved exercise capacity and cardiac output were observed without any major side effects in both patients. The iloprost inhalation therapy was well tolerated and effective for the symptomatic treatment of Fontan patients.

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.137-143
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• 2014

Asbestos is given to a variety of six naturally occurring silicate minerals. These minerals possess high tensile strength, flexibility, resistance to chemical and thermal degradation, and electrical resistance. These minerals have been used for decades in thousands of commercial products, such as insulation and fireproofing materials, automotive brakes, textile products, cement and wallboard materials. When handled, asbestos can separate into microscopic-size particles that remain in the air and are easily inhaled. It is now known that prolonged inhalation of asbestos fibers can cause serious and fatal illnesses including malignant lung cancer, mesothelioma, and asbestosis. Therefore the use of asbestos and asbestos products has dramatically decreased in recent years. Also all constructions including asbestos should be removed under strictly controlled conditions and very tightly implemented health & safety management systems. In this study, the process of the removal work of the asbestos cement slate was analyzed by IDEF-0 modeling and evaluated by 4M risk assessment method. The results show that removal work of the asbestos cement slate was classified five process and eighteen detail process. The risk of safety side the higher than the risk of health side in 4M risk assessment.

• Tuberculosis and Respiratory Diseases
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• v.45 no.1
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• pp.99-106
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• 1998

Background: Bronchial asthma is a complex disease, which is characterized by spontaneous exacerbations of airway obstruction and persistent bronchial hyperresponsiveness. Animal models have fallen short of reproducing the human disease, particularly in mimicking the spontaneous and persistent airflow obstruction that characterized in asthma. In animals, airflow obstruction is usually assessed by measuring airflow resistance during tidal breathing under such invasive technique as tracheostomy and anesthesia. A noninvasive technique for measuring pulmonary function in small animals is needed to evaluate long-term changes in lung function during the course of experimentally produced disease without sacrificing the animal. Purpose: The purpose of this study was to evaluate early bronchoconstrcition after allergen challenge and airway responsiveness (AR) to inhaled methacholine in nonanethetized, unrestrained guinea pigs. Method: Guinea pig model of asthma was sensitized by subcutaneous injection with ovalbumin and challenged by inhalation of aerosolized ovalbumin(1% wt/vol ovlabumin). Airflow obstruction of conscious guinea pig was measured as specific airway resistance (airway resistance $\times$ thoracic gas volume). Airway resistance and thoracic gas volume of conscious guinea pig were assessed by body plethysmography before challenge and at regular intervals for as long as 30 minutes after challenge. AR to aerosolized methacholine of asthma group was compared with that of control group in body plethysmography. Result: Asthma model<> developed in 13 (65%) among 20 guinea pigs, in which early responses occurred in the airways after the exposure to inhalation with ovalbumin. Airway challenge with ovalbumin caused increase in specific airway resistance, which peaked at 6 minutes and amounted to a $231.5{\pm}30.4%$ increase from baseline. AR to aerosolized methacholine of asthma model increased significantly compared with control group. Conclusion: These results have showed a useful animal model to evaluate early bronchoconstrcition after allergen challenge and airway responsiveness in nonanethetized, unrestrained guinea pigs.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.4
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• pp.283-290
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• 2017

Objectives: This study aimed to evaluate the relationship between filter replacement and filter performance change in particulate filters used in the workplace. Methods: Three types of particulate respirator filters are mainly used in the workplaces. These were tested against the filter performance safety certification standard for dust masks established by the Ministry of Employment and Labor(MoEL). Used filters were collected to test their performance, such as filter pressure drop, efficiency, and quality factors. All these factors were evaluated by a filter tester. To compare filter performance between used and new ones, the same kinds of new filters were also tested together under the same procedures. Results: A total of 270 used filters were collected for testing. The main reasons to replace the filters were difficulty in breathing(46.2%), dirty/odor influx(19.7%), and a combination of factors(26.7%). The pressure drop for two special class groups was significantly different(new filters: $20.72{\pm}3.33mmH_2O$; used filters: $24.70{\pm}5.26mmH_2O$, p<0.0001). In the case of penetration, new filter groups indicated $0.0032{\pm}0.0040%$, while that of the used filters was $0.0596{\pm}0.1187%$. The quality factor for the used filters($0.34{\pm}0.09$) significantly decreased compared to the new filters($0.53{\pm}0.08$) (p<0.0001). Conclusions: Filter performance including pressure drop, penetration, and the quality factor was evaluated and compared between new and used filters in the workplace. The results showed that general filter performance deteriorated more for change of pressure drop, penetration and the quality factor.