• Tuberculosis and Respiratory Diseases
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• v.65 no.5
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• pp.379-384
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• 2008

Background: Sputum decontamination with NALC-NaOH (N-acetyl-L-cysteine-sodium hydroxide) is known to better detect Mycobacterium tuberculosis (M. tb) by culture than that with using NaOH, which is widely used in Korean hospitals. In this report, sputum samples collected from pulmonary tuberculosis (TB) patients were treated with either NaOH or NALC-NaOH, and we compared the results of smear and culture positivity to determine whether the NALC-NaOH treatment method improves culture positivity in the sputum samples, and especially for those sputum samples that are smear negative and scanty. Methods: For each decontamination method, 436 sputum samples from pulmonary TB patients in the National Masan Tuberculosis Hospital were collected for this study. Sputum from a patient was collected two times for the first and second day of sampling time, and these samples were employed for the decontamination process by performing the 4% NaOH and NALC-2% NaOH treatment methods, respectively, for detecting M. tb by an AFB (Acid Fast Bacilli) smear and also by culture in solid Ogawa medium. Results: The NaOH and NALC-NaOH treatment methods did not significantly affect the AFB smear positivity of the sputum samples (33.0% vs 39.0%, respectively, p=0.078). However, the culture positive percents of M. tb in the Ogawa medium treated with NALC-NaOH and NaOH were 39.7% and 28.0%, respectively, which was a significantly different (p=0.0003). This difference in culture was more prominent in the sputum samples that were smear negative (the positive percents with NALC-NaOH and NaOH were 15.8% and 7.2%, respectively, p=0.0017) and scanty (NALC-NaOH and NaOH were 60.8% and 42.9%, respectively, p=0.036), but not for a smear that was 1+ or higher (p>0.05). Conclusion: NALC-NaOH treatment is better than NaOH treatment for the detection of M. tb by culture, but not by smear, and especially when the AFB smear is negative and scanty.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.3
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• pp.212-221
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• 2013

Objectives: Asbestos fibers are accumulated in negative pressure unit (NPU) or vacuum cleaner in asbestos removal. Failure of operation or poor use performance of the NPU or vacuum cleaner causes asbestos fibers to spread in the air. Asbestos contractors should have an NPU fitted with a HEPA , vacuum cleaner, decontamination area, respirators, wetting equipment, and differential pressure manometer to register with the Ministry of Employment and Labor. There should be performance criteria of equipment used in asbestos removal. But there are none such criteria used in asbestos removal. This study was performed to investigate international or national performance criteria of equipment used in asbestos removal. Methods: Regulations, approved code of practice, guidance and national standards of the UK, USA and Korea were reviewed. A survey was done to investigate the requirements for equipment used in asbestos removal in Korea. Results: Air flow of NPUs used in Korea usually covers from$500m^3/h$ to over $3000m^3/h$. Some requirements for NPUs used in Korea were missing compared to the requirements of British standards for NPUs. All NPUs have different missing requirements. The UK also has separate British standard for leak tests for NPUs. Highly hazardous class vacuum cleaners should be used in asbestos removal in the UK. It has national standards on the operation of vacuum cleaners used in asbestos removal. There is only a certification system for less than 2.5kw rated voltage vacuum cleaners for home use in Korea. Powered (-assisted) respirators with mask are recommended in asbestos removal. Type 5 coveralls should be used in asbestos removal in the UK. There are international standards for requirements and leak tests of type 5 coveralls. A manometer for measuring differential pressure is needed in asbestos removal. The manometer's measuring range should cover less than ${\pm}125$ Pa and the gradation of manometer should be less than 2.5 Pa. The definition of decontamination area should be corrected. Installation of airlock and minimum area should be considered in decontamination area. Conclusions: Equipment should be used in asbestos removal proper performance and no leaks. There should be a certification system for equipment used in asbestos removal. This study can help to a certification system for equipment used in asbestos removal in Korea.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.2
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• pp.149-157
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• 2005

PFC(Perfluorocarbon) decontamination process is one of best methods to remove hot particulate adhered at inside surface of hot cell and surface of equipment in hot cell. It was necessary to develop a particulate filtration equipment to reuse PFC solution used on PFC decontamination due to its high cost and to minimize the volume of second wastewater. Contamination characteristics of hot particulate were investigated and then a filtration process was presented to remove hot particulate in PFC solution generated through PFC decontamination process. The removal efficiency of PVDF(Poly vinylidene fluoride), PP(Polypropylene), Ceramic(Al$_{2}$O$_{3}$ filter showed more than 95$\%$. The removal efficiency of PVDF filter was a little lower than those of other kiters at same pressure(3psi). A ceramic filter showed a higher removal efficiency with other filters, while a little lower flux rate than other filters. Due to inorganic composition, a ceramic filter was highly stable against radio nuclides in comparison with PVDF and PP membrane, which generate H$_{2}$ gas in e-radioactivity atmosphere. Therefore, the adoption of ceramic filter is estimated to be suitable for the real nitration process.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.2
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• pp.161-170
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• 2006

PFC(Perfluorocarbon) decontamination process is one of best methods to remove hot particulate adhered on the inner surface of hot cell and surface of equipment in hot cell. It was necessary to develop a filtration equipment to reuse the PFC waste solution generated on PFC decontamination due to the high cost of PFC solution and for minimization of the volume of second waste solution. The filtration equipment was developed to remove hot particulate in PFC waste solution. It was made suitable size and weight in consideration of hot cell gate and crane. And it has wheels for easy movement. Flux of the filtration equipment decreased with particulate concentration increase. It consists of pre-filter($1.4{\mu}m$) and final-filter($0.2{\mu}m$) for protection of the flux decrease along filtration time. It treatment capacity of waste solution is 0.2 L/min.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.1
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• pp.95-114
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• 2023

During the decades after the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, ambient dose rates have markedly decreased when compared to those at the early state of the accident. Government projects have been continuously conducted by surveying the ambient dose rate and radiocesium distributions. Airborne surveys using crewed helicopters and unmanned aerial vehicles (UAVs) are the best methods for obtaining an overall picture of the distribution. However, ground-based surveys are required for accurate measurements near the population. The differences between these methods include the knowledge of the post depositional behavior of radionuclides in land use. The survey results form the basis for policy decisions such as lifting evacuation zones, decontamination, and other countermeasures. These surveys contain crucial findings regarding post-accident responses. This paper reviews the survey methods of government projects and current situation around the FDNPS. The visualization methods and databases of ambient dose rates are also reviewed to provide information to the population.

• Journal of Korean Dental Science
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• v.9 no.1
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• pp.19-27
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• 2016

Purpose: Laser treatment has become a popular method in implant dentistry, and lasers have been used for the decontamination of implant surfaces when treating peri-implantitis. This study was performed to evaluate the effects of an Erbium-doped:Yttrium-Aluminum-Garnet (Er:YAG) laser with different settings on machined (MA), sand-blasted and acid-etched (SA), and resorbable blast media (RBM) titanium surfaces using scanning electron microscopy and confocal microscopy. Materials and Methods: Four MA, four SA, and four RBM discs were either irradiated at 40 mJ/20 Hz, 90 mJ/20 Hz, or 40 mJ/25 Hz for 2 minutes. The specimens were evaluated with scanning electron microscopy and confocal microscopy. Result: The untreated MA surface demonstrated uniform roughness with circumferential machining marks, and depressions were observed after laser treatment. The untreated SA surface demonstrated a rough surface with sharp spikes and deep pits, and the laser produced noticeable changes on the SA titanium surfaces with melting and fusion. The untreated RBM surface demonstrated a rough surface with irregular indentation, and treatment with the laser produced changes on the RBM titanium surfaces. The Er:YAG laser produced significant changes on the roughness parameters, including arithmetic mean height of the surface (Sa) and maximum height of the surface (Sz), of the MA and SA surfaces. However, the Er:YAG laser did not produce notable changes on the roughness parameters, such as Sa and Sz, of the RBM surfaces. Conclusion: This study evaluated the effects of an Er:YAG laser on MA, SA, and RBM titanium discs using confocal microscopy and scanning electron microscopy. Treatment with the laser produced significant changes in the roughness of MA and SA surfaces, but the roughness parameters of the RBM discs were not significantly changed. Further research is needed to evaluate the efficiency of the Er:YAG laser in removing the contaminants, adhering bacteria, and the effects of treatment on cellular attachment, proliferation, and differentiation.

• Journal of The Korean Society of Clinical Toxicology
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• v.11 no.1
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• pp.1-8
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• 2013

Gastric lavage is one of gastrointestinal decontamination methods which have been controversial in the clinical toxicology field for a long time. Expert groups of American and European clinical toxicologists have published the position papers regarding gastric lavage three times since 1997. They recommended that gastric lavage should not be used as a routine procedure in the management of acute intoxication, because they thought that there is no certain evidence of improving clinical outcome by its use. However, the studies they reviewed were not well-controlled randomized trials, which cannot be conducted in the clinical toxicology field due to variability of patients and ethical problems. Therefore, the results from these studies should be interpreted with caution. They also insisted that gastric lavage can be undertaken within 60 minutes of ingestion. The limitation of one hour after ingestion is too arbitrary and may cause a lot of misunderstanding. Formation of pharmacobezoar or gastric hypomotility after ingestion may significantly delay the gastric emptying time so that gastric lavage can be useful even after several hours or more in case of highly toxic substances or severe intoxication. Furthermore, as there are a number of serious intoxication by toxic pesticides with large amount in suicidal attempts in Korea, it seems that gastric lavage may be used more frequently in Korea than in Western countries. When deciding whether or not to use gastric lavage, all the indications, contraindications, and possible adverse effects should be taken into account on the basis of risk-benefit analysis. If the procedure is decided to be done, it should only be performed by well-trained experts.

• Journal of Periodontal and Implant Science
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• v.49 no.5
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• pp.319-329
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• 2019

Purpose: Direct application of atmospheric-pressure plasma jets (APPJs) has been established as an effective method of microbial decontamination. This study aimed to investigate the bactericidal effect of direct application of an APPJ using helium gas (He-APPJ) on Porphyromonas gingivalis biofilms on sandblasted and acid-etched (SLA) titanium discs. Methods: On the SLA discs covered by P. gingivalis biofilms, an APPJ with helium (He) as a discharge gas was applied at 3 different time intervals (0, 3, and 5 minutes). To evaluate the effect of the plasma itself, the He gas-only group was used as the control group. The bactericidal effect of the He-APPJ was determined by the number of colony-forming units. Bacterial viability was observed by confocal laser scanning microscopy (CLSM), and bacterial morphology was examined by scanning electron microscopy (SEM). Results: As the plasma treatment time increased, the amount of P. gingivalis decreased, and the difference was statistically significant. In the SEM images, compared to the control group, the bacterial biofilm structure on SLA discs treated by the He-APPJ for more than 3 minutes was destroyed. In addition, the CLSM images showed consistent results. Even in sites distant from the area of direct He-APPJ exposure, decontamination effects were observed in both SEM and CLSM images. Conclusions: He-APPJ application was effective in removing P. gingivalis biofilm on SLA titanium discs in an in vitro experiment.

• Journal of Radiation Protection and Research
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• v.47 no.1
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• pp.30-38
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• 2022

Background: Residential areas have some factors on the external exposure of residents, who usually spend a long time in these areas. Although various survey has been carried out by the government or the research institutions after the Fukushima Daiichi Nuclear Power Plant accident, the mechanism of radiocesium inventory in the terrestrial zone has not been cleared. To better evaluate the radiation environment, this study investigated the temporal changes in air dose rate and ¹³⁷Cs inventories (Bq/m²) in residential areas and agricultural fields. Materials and Methods: Air dose rate and ¹³⁷Cs inventories were investigated in residential areas located in an evacuation zone at 5-8 km from the Fukushima Daiichi Nuclear Power Plant. From December 2014 to September 2018, the air dose rate distribution was investigated through a walking survey (backpack survey), which was conducted by operators carrying a γ-ray detector on their backs. Additionally, from December 2014 to January 2021, the ¹³⁷Cs inventories on paved and permeable grounds were also measured using a portable γ-ray detector. Results and Discussion: In the areas where decontamination was not performed, the air dose rate decreased faster in residential areas than in agricultural fields. Moreover, the ¹³⁷Cs inventory on paved surfaces decreased with time owing to the horizontal wash-off, while the ¹³⁷Cs inventory on permeable surfaces decreased dramatically owing to the decontamination activities. Conclusion: These findings suggest that the horizontal wash-off of ¹³⁷Cs on paved surfaces facilitated the air dose rate decrease in residential areas to a greater extent compared with agricultural fields, in which the air dose rate decreased because of the vertical migration of ¹³⁷Cs. Results of this study can explain the faster environmental restoration in a residential environment reported by previous studies.

• The Journal of Advanced Prosthodontics
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• v.14 no.5
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• pp.273-284
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• 2022

PURPOSE. Computer-aided design and manufacturing (CAD-CAM) of implant abutments has been shown to result in surface contamination from site-specific milling and fabrication processes. If not removed, these contaminants can have a potentially adverse effect and may trigger inflammatory responses of the peri-implant tissues. The aim of the present study was to evaluate the bacterial disinfection and cleaning efficacy of ultrasonic reprocessing in approved disinfectants to reduce the microbial load of CAD-CAM abutments. MATERIALS AND METHODS. Four different types of custom implant abutments (total N = 32) with eight specimens in each test group (type I to IV) were CAD-CAM manufactured. In two separate contamination experiments, specimens were contaminated with heparinized sheep blood alone and with heparinized sheep blood and the test bacterium Enterococcus faecium. Abutments in the test group were processed according to a three-stage ultrasonic protocol and assessed qualitatively and quantitatively by determination of residual protein. Ultrasonicated specimens contaminated with sheep blood and E. faecium were additionally eluted and the dilutions were incubated on agar plates for seven days. The determined bacterial counts were expressed as colony-forming units (CFU). RESULTS. Ultrasonic reprocessing resulted in a substantial decrease in residual bacterial protein to less than 80 ㎍ and a reduction in microbiota of more than 7 log levels of CFU for all abutment types, exceeding the effect required for disinfection. CONCLUSION. A three-stage ultrasonic cleaning and disinfection protocol results in effective bacterial decontamination. The procedure is reproducible and complies with the standardized reprocessing and disinfection specifications for one- or two-piece CAD-CAM implant abutments.