• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.2
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• pp.178-185
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• 1998

In order to evaluate and improve the performance of local exhaust ventilation systems for two TCE degreasing (A, B) and two electroplating (C, E) and one acid dipping & plating (D) operations located in Kimhae, the performance test was conducted with trace gases and a thermal anemometer (Kanomax 24-6111, Japan). For the inadequately designed systems, the improvement and redesigns in compliance with recommendation by ACGIH was suggested. The results of performance test for each system are as follows; 1. System of Workplace A was generally well-designed. Actual exhaust air flow rate was in excess of 68% above the recommended standard exhaust air flow rate. 2. System of Workplace B was very well-designed and completely enclosed. 3. All systems of Workplace C including hoods were poorly-designed and actual exhaust air flow rates were insufficient for open tanks. All systems should be upgraded according to ACGIH recommendations. 4. Supply and exhaust air flow rate of push-pull exhaust systems in Workplace D should be greatly increased. The width of flange of dipping tank hood should be increased with the value suggested. 5. System of Workplace E was well-designed. Actual exhaust air flow rate was in excess of 54% above the required.

• Journal of Korean society of Dental Hygiene
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• v.18 no.2
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• pp.227-237
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• 2018

Objectives: This study aims to recognize the importance of dental hygiene process diagnosis of dental hygiene process which can comprehensively grasp the patient's problem and to use it as a basis for establishing the patient's preventive treatment plan. Methods: This study did survey to 443 patients who received treatment based on the oral health care program from a dental clinic in Busan from January 2015 to January 2017. Data analysis was performed using IBM SPSS Statistics (Version 21.0), and statistical significance level was set at ${\alpha}=0.05$. Binary logistic regression analysis was performed to the dental hygiene problems affecting the dental hygiene plan. Results: There were significant differences in dental hygiene problems between male and female respondents on various dental problems such as dental plaque deposition, attrition, stain, dental fear, possibility of jaw joint disorder, food pressing, possibility of malocclusion. There were also significant differences in dental hygiene plans between male and female respondents in air-Jet, non-smoking education, and sealant. The most common dental hygiene plan was scaling, The problem of stain showed that the scaling plan was 0.20 times less. The explanatory power of the model was 43.5%, and the Hosmer and Lemeshow tests were 0.345. Conclusions: Therefore, if we continue to study the factors affecting the dental hygiene problems and the plan, we can reduce the burden of the dental hygienists applying the dental hygiene process in the dental clinic. And, it is expected that the oral health care program using the dental hygiene process will spread to the dental clinic as an excellent oral preventive program.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.3
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• pp.359-364
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• 2014

Objectives: The principal aim of this study is to provide fundamental data for suggesting substantial management plan of personal air sampler by investigating current situation of work environment monitoring service provider. Materials and Methods: The questionnaires regarding a personal air sampler were sent by electronic mail to 150 institutions, except for 22 institutions which are out of business or closed temporarily, among total 172 domestic work environment monitoring service providers designated by Ministry of Employment and Labor based on 2013. The institutions which did not reply to the questionnaire for 30 days were required directly by phone call. Finally 97 institutions gave an answer to the questionnaire and therefore the respondence rate was 65%. Results: The normal operation rate of personal air sampler exceeded 70% in all the types (particle, gas and both combination) in terms of purchased year. Furthermore the personal air sampler purchased recently showed a trend of high operation rate compared to the personal air sampler purchased previously. The distribution patterns of personal air sampler In terms of manufacturers were Gillian>MSA>SKC for particle, Gillian>SKC>AMETEK for gas and Gillian>MSA>Casella for both combination, respectively. As a result, it was found that the personal air sampler manufactured by Gillian company was utilized the most in domestic work environment monitoring service provider regardless of types of personal air sampler. Conclusions: Based on the results obtained from this study, the normal operation rate according to types of personal air sampler was as follows: 94% for personal air sampler for collecting particle only, 93% for personal air sampler for collecting gas only and 89% for collecting both particle and gas. Overall, the numbers of personal air sampler possessed and operated normally in domestic work environment monitoring service provider were 5,458 and 5,062, which indicates the normal operation rate of personal air sampler in total aspect is 93%.

• Journal of Food Hygiene and Safety
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• v.11 no.3
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• pp.221-225
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• 1996

For the purpose of improving hygienic quality of health-foods, sterilization effects of ${\gamma}$-ray and ozone on microoganisms associated with food cultured in the media and contaminated in Angelica keiskei powder were investigated. Ozone was immersed in water and sprayed in air, on the concentration of 3 mg liter-1 at an air flow rate of 5 liter min-3. Test strains cultured in the media completely inhibited by ${\gamma}$-ray at irradiation doses of 0.25~2 kGy. In the case of ozone, test bacteria inactivated after treatment of 10~20 minutes, but test mold, Aspergillus flavus was not effective. Strains contaminated in Angelica keiskei powder completely inhibited by ${\gamma}$-ray at irradiation doses of 2.5~7.5 kGy. However, when the powder was sprayed with ozonized air for 10hours, Bacillus subtilis and Staphylococcus aureus among five strains were eliminated.

• Journal of the Korean Society of Safety
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• v.9 no.1
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• pp.134-139
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• 1994

In order to assess the level of atmospheric pollution and to contribute the hearth improvement of residents in Taejon city, the authors were measured the concentration of air pollutants(CO, SO$_2$, NO$_2$, TSP, Pb, Cd, Cr) at three places of the control road in Taejon. The investigative research performed bimonthly from May 1993 to September 1993, and the places were the underground shopping stores of Taejon station, Dongyang department store and provincial goverment areas. The results of statistical analysis are as followings. \circled1CO :0.569~0.966ppm \circled2SO$_2$：0.084~0.170ppm \circled3NO$_2$:0.0045~0.022ppm \circled4TSP：249~299$\mu\textrm{g}$/㎥. \circled5Pb :0.366~1.157$\mu\textrm{g}$/㎥. \circled6Cd：0.016~0.025$\mu\textrm{g}$/㎥. \circled7 Cr : 0.198 ~0.290$\mu\textrm{g}$/㎥. The mean concentration of SO$_2$in Dongyang department store area was 0.17ppm, and it exceeded the ambient air quality standard by 0.02ppm. The concentration of TSP was higher than a standing rule of public hygiene, and it was very near to a standing rule of environmental preservation. The standing rule of indoor air pollution in underground shopping store have two different laws, the public hygiene and the environmental preservation. Therefore, it was difficult to judge what to do in such circumstance. In regarding to the laws, an environmental standard for air pollution in the underground space must unify into the standard of public hygiene.

• Journal of Food Hygiene and Safety
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• v.26 no.4
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• pp.361-365
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• 2011

To evaluate the indoor air quality of food manufacturing plants, the presence of viable bacteria and fungi was assessed in the indoor air of the facilities at which 9 food items were manufactured. Air samples were collected from the general zone, low clean zone and clean zone of each factory with an air sampler, in combination with plate counts agar using for bacteria, and dichloran-glycerol agar for fungi. The samples were incubated at $25^{\circ}C$ for 4 to 7 days. After culture, the colony forming units (CFU) on each plate were counted and corrected with a positive hole conversion table. The average concentration of bacteria was $2.2{\times}10^3\;CFU/m^3$ in the general zone, $1.2{\times}10^3\;CFU/m^3$ in the low clean zone and $7.3{\times}10^2\;CFU/m^3$ in the clean zone. The average concentration of fungal microbes was $2.5{\times}10^3\;CFU/m^3$ in the general zone, $2.6{\times}10^3\;CFU/m^3$ in the low clean zone, and $2.0{\times}10^2\;CFU/m^3$ in the clean zone. No meaningful differences were detected between the general zone and the low clean zone, but the clean zone had significantly lower concentrations than the other zones. Additionally, the identification of the fungi was performed according to morphological method using a giant culture and slide culture. The fungi were identified as belonging to 18 genera, and the genera Cladosporium(33%), Penicillium(29%) and Aspergillus(26%), predominated. Aspergillus isolates were identified to species level, and A. ochraceus, a mycotoxigenic species, was identified. As part of the effort to control the quality of the indoor air of food manufacturing plants, our results show that continued studies are clearly warranted.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.2
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• pp.190-199
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• 2018

Objectives: The purpose of this case study is to assess the current airflow and find the ideal ventilation conditions in tank reactors for minimizing the possibility of exposure respiratory dusts(size of $2.5{\mu}m$, $10{\mu}m$) when workers exchange catalysts in the tank reactors. Methods: A Numerical study was performed to determine ideal ventilation conditions, We considered two sizes of airborne respiratory particles($2.5{\mu}m$, $10{\mu}m$) at 12points from the bottom of tank reactor. We changed input & output ventilation conditions and analyzed the particle motion in the tank reactor. The star-ccm+, computational fluid dynamics tool was used to predict air & particle flow patterns in the tank reactor and a numerical simulation was achieved by applying the realized ${\kappa}-{\varepsilon}$ turbulence model and the Lagrangian particle tracking method. Results: From the results, the increase of recirculation air had a significant impact on removing dusts because they are removed by HEPA filter. To the contrary, Increasing the clean air quantity or changing the input position of clean air is not good for workers because it causes the exit of respiratory dusts through workers' entrance or cause it to remail suspended in the air in the workplace tank.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.3
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• pp.160-165
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• 2005

Schools have significant and serious indoor environmental health problem, of which indoor air quality (IAQ) in school building may affect the health of the students and indirectly affect learning performance. Schools are of special concern when regarding indoor exposure to air pollutants, because students are particularly sensitive to pollutants and spend a significant amount of time in that environment. Therefore researches for improvement of indoor air quality have been developed such as installation of air cleaning device, ventilation system, titanium dioxide(TiO2) coating and so on. However, it is difficult to evaluate the magnitude of improvement of indoor air quality in field study because indoor air quality can be affected by source generation, outdoor air level, ventilation, decay by reaction, temperature, humidity, mixing condition and so on. In this study, evaluation of reduction of formaldehyde emission rate in school indoor environments by far-Infrared ray coating material was carried out using mass balance model in indoor environment. we proposed the evaluation method of magnitude of improvement in indoor air quality, considering outdoor level and ventilation. Since simple indoor concentration measurements could not properly evaluate the indoor air quality, outdoor level and ventilation should be considered when evaluate the indoor air quality.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.3
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• pp.414-419
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• 2019

Objectives: The objective of this study was to evaluate the inhibitory effect of non-thermal dielectric barrier discharge (DBD) plasma by air volume against Mycobacterium tuberculosis (MTB). Methods: Plasma generators (TB-300, Shinyoung Airtec, Seongnam-si, Korea) were operated in a 2A type biosafety cabinet. The plasma generator was set to a wind flow rate of 14 ($80m^3/h$), 18 ($110m^3/h$), and 22 ($150m^3/h$), and exposure times were set to 0 hours, 3 hours, 6 hours, 9 hours, and 24 hours. Results: The inhibitory effects of plasma at air volume 14 with prolonged exposure time of three hours was 20%, 64% at six hours, 82.3% at nine hours, and 100% after 24 hours exposure. With air volume of 18, the inhibitory effects upon plasma exposure were 36% for three hours, and 100% from 24 hours. Greater air volume resulted in greater inhibition of tuberculosis bacterial growth. In particular, the maximum inhibitory effect (100%) was shown in air volume of 22 ($150m^3/h$) after three hours of plasma exposure. Conclusions: The results showed the correlating inhibitory effects of plasma on the growth of MTB in combination with increasing plasma exposure time and air volume.

• Journal of The Korean Digital Architecture Interior Association
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• v.11 no.1
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• pp.5-13
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• 2011

This research proposed the space planing methode and diagrams of restaurant kitchens to improve hygiene by analyzing the related contents collected from books and researches in interior design and HACCP (Hazard Analysis and Critical Control Point). HACCP is an effective and scientific hygiene system for food safety in order to prevent cross-contamination from food hazards. Based on the analyses, improvement of food production environments like restaurant kitchens is necessary for food hygiene. The space planing methode of restaurant kitchens to improve hygiene are followings: The circulation planing is that the direction of movement of the food, workers, waste, and dishes should be fractionated and managed for cross-contamination prevention. The space separation planing is that the spaces in the kitchen should be classified and divided into contaminated area and non-contaminated and clean area depending on the degree of cleanliness. The zoning is space arrangement with feed-back process to check the possible points of cross-contamination and correct space arrangement until the possibility of cross-contamination disappear in kitchen. However, if cross-contamination is unavoidable in some points in restaurant kitchens, hygiene facilities such as washing rooms, pass rooms, and double doors with air-shower should be located in order to remove contamination.