• Corrosion Science and Technology
• /
• 제14권6호
• /
• pp.273-279
• /
• 2015

Effects of passive film quality by chemical passivation and solution flow on the corrosion behavior of 304 stainless steel in HCl solution were investigated using a coloration indicator, and by corrosion weight loss, electrochemical polarization and element dissolution measurements. A high redness degree suggests a low passive-film integrity for 304 stainless steel following air exposure, while the minimum redness degree for the samples after chemical passivation suggests a high passive-film integrity. In the static condition, samples subjected to air exposure exhibited a high corrosion rate and preferential dissolution of Fe. Chemical passivation inhibited the corrosion rate due to the intrinsically high structural integrity of the passive film and high concentrations of Cr-rich oxides and hydroxide. Solution flow accelerated corrosion by promoting both the anodic dissolution reaction and the cathodic reaction. Solution flow also altered the preferential dissolution to fast uniform dissolution of metal elements.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제25권3호
• /
• pp.65-73
• /
• 2020

Exposure assessment methodology for outdoor air inhalation pathways (i.e., inhalation of volatile compounds and fugitive dust in outdoor air) was investigated. Default values of several parameters currently used in Korea (e.g., Q/C; inverse value of concentration per unit flux, and frs; soil fraction in PM10) may not be suitable and lack site-specificity, as they have been adopted from the risk assessment guidance of the United States or the Netherlands. Such limitation can be addressed to a certain degree by incorporating the volatilization factor (VF) and the particulate emission factor (PEF) with Box model. This approach was applied to an exposure assessment of a site contaminated with petroleum hydrocarbons in Korea. The result indicated that the suggested methodology led to more accurate site-specific exposure assessment for outdoor inhalation pathways. Further work to establish methodology to determine site-specific Q/C values in Korea needs to be done to secure the reliability of the exposure assessment for outdoor air inhalation pathways.

• 유통과학연구
• /
• 제17권7호
• /
• pp.65-76
• /
• 2019

Purpose - The purpose of this study is to investigate economical ventilation effectiveness to reduce hazardous materials exposure and damage of workers by analyzing exposure amount of noxious substances under various ventilation conditions of nail salon for indoor environments. Research design, data, and methodology - This study was carried out with cooperation of Nail shop located in SeongNam city to involve an analysis of the environmental impact indoor air quality, pollutant exposure and economical cost-effectiveness in the nail workplace. The hazardous substances were PM-10(Particulate Matter-10㎛), VOCs(Volatile Organic Compounds) and Formaldehyde, which are the major materials of nail workplace. Results - PM-10 is reduced by about 60% with air cleaner, forced artificial ventilation by 32%, and natural ventilation by about 12%. TVOCs and Formaldehyde showed similar efficiency (80~100%) after natural ventilation and ventilation after 60 minutes. The removal efficiencies of VOCs and formaldehyde were similar to those of natural ventilation and mechanical ventilation system. However, in case of dust, natural ventilation was reduced by artificial ventilation system due to inflow of external dust during natural ventilation. Conclusions - If the pollution degree of outdoor air is not high, air volume is high, and natural ventilation is performed when the air conditioning and heating system is not operated. Even at the end of the work, it keeps operating for 60 minutes to remove the pollutants generated. Results of this analysis demonstrated that the worker environment can be improved by adopting institutional legislation and guidelines for ventilation.

• 한국분무공학회지
• /
• 제10권1호
• /
• pp.1-9
• /
• 2005

When the water jets heated up to the saturation temperature at a high line pressure are sprayed into a reduced (atmospheric) pressure through an air-assisted nozzle, the jets experience sudden exposure into a reduced pressure, get superheated and produce steam bubbles while atomization processes of jets are taking place. This process is called flash atomization. In this study the flash atomization of superheated water jets assisted by air has been studied. Sprays with flash atomization have been photographed at various water and air flow rates and water superheats. It has been found that the spray angle with flash atomization increases with water superheat and water flow rate but decreases with air flow rate. The degree of change of spray angle has been analyzed and correlated as a function of superheat, air and water flow rates.

• 한국자원식물학회지
• /
• 제18권3호
• /
• pp.505-511
• /
• 2005

삼백초 수확 후 광 노출정도에 따른 선도유지 및 유효성분 함량 변화를 구명하여 품질향상을 위한 기초자료를 제공하고자 시험을 수행한 결과, 건물율은 잎, 줄기, 꽃 모두 광노출 시간이 길수록 높았으며, 색도중 명도는 광노출시간이 짧을수록 높았으나, 적색도는 상반된 경향이었다. 황색도와 채도는 건조전에는 광노출 2시간시에, 건조후에는 광노출시간이 짧을수록 높았으나, 경엽 탕전시에는 상반된 경향이었고, 광노출 시간이 짧을수록 rutin, quercitri 의 함량과 떫은 맛이 많았고, 품질 선호도와 경엽 탕전 시 기호도도 우수하였다.

• 한국대기환경학회지
• /
• 제7권3호
• /
• pp.219-226
• /
• 1991

Results from study on physiological responses to $SO_2$ of Quercus spp. selected for restoration of vegetation damaged by air pollution in the field study were as follows. Tolerance of Quercus aliena, Q. acutissima and Q. mongolica used in this study to $SO_2$ was higher in that order and tolerance of these plants to $SO_2$ was high comparatively among trees composing of major forest vegetation of Korea including natural forests and plantations. Stomatal resistance of these plants was increased after exposure to $SO_2$ and range of increase was different among species. From discrepancy between order of tolerance to $SO_2$ and range of increase in stomatal resistance, we were estimated that resistance mechanisms of Quercus spp. were different among species as mechanism originated in avoidance and resistance, respectively. Water potential of plant leaves reduced after exposure to $SO_2$, degree of reduction accorded with order of tolerance to $SO_2$. Reduction of water potential of plants after exposure to $SO_2$ was initiated before appearance of visible damage in plant leaves and water potential of plants exposed to $SO_2$ of low concentration, in which plants were not showed viaible damage was also reduced.

• 한국주거학회:학술대회논문집
• /
• 한국주거학회 2005년도 추계학술대회 논문집
• /
• pp.295-300
• /
• 2005

This Study intends to find out the subjective symptom of Construction Business Worker caused by chemical material exposure, also willing to research how much they are exposed to VOCs(Volatile Organic Compounds) and under how much harmful circumstance they are working. As the results, the job group among construction business workers which is most highly dangerous degree to be taken ill of Multiple Chemical Sensitivity is Interior Worker, next following by order of Clerical Worker, Exterior Worker. According to this result, the continuous exposure in high density must be prevented by the measures for Interior Worker also to be bestowed a compulsory break during working hour for regular exposure to the open air,

• 한국환경과학회지
• /
• 제18권3호
• /
• pp.345-353
• /
• 2009

The purpose of this study is to examine the health of beauty salon workers through the utilization of questionnaires concerning the extent of exposure to organic solvents found in the air of some beauty salons and any resultant symptoms in employees. The subjects were 36 employees from 10 beauty salons who agreed to participate in this study. The degree of exposure to organic solvents in the air of beauty salons was measured from September 1, 2008 to September 30, 2008. A survey of symptoms that occurred due to exposure to these solvents was also performed. The results were as follows: questionnaires were collected and analyzed from a total of 36 subjects. Of these, 28(77.8%) were female and 8(22.2%) were male. The mean age was 29.08. The mean working period was 7.13 years. Sixteen subjects attended programs at universities while 11 went to beauty schools for vocational education. When testing the concentration of organic solvents in the air of beauty salons, the highest value found was Isopropyl alcohol 511.85 ppb followed by butyl acetate, toluene, acetone, xylene, ethyl benzene, styrene, and chlorobenzene. A logistic regression analysis was performed as follows: the point of each factor was the dependent variable while sex, age, drinking, smoking, educational level, work experience, hairdresser's license, and organic solvents were the independent variables. Statistically significant difference (p<0.05) was shown in the hairdresser's license among Factor 1 and in Xylene among Factor 2; however, difference was not shown in the other variables.

• 한국산업보건학회지
• /
• 제33권4호
• /
• pp.395-402
• /
• 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.

• Journal of Nutrition and Health
• /
• 제24권1호
• /
• pp.12-19
• /
• 1991

장기간의 연속적 오존조사와 식이항산화제 및 식이지방의 불포화도가 생쥐의 폐와 간조직의 지질산화에 미치는 영향을 조사하였다. 실험동물들은 각각 0.25ppm, 0.50ppm의 오존 또는 정상적 대기환경에서 18개월간 식이항산화제의 수준과 식이지방의 불포화도를 달리한 실험식이들에 의해 사육되었으며 조직의 지질과산화의 정도는 Thiobarbituric acid 반응물질의 농도와 free malonaldehyde의 농도에 의해 측정되었다. 본 연구의 결과, 장기간의 오존조사는 실험식이의 종류에 관계없이 폐조직과 간조직의 지질과산화를 유도하지 않음이 발견되었으며 식이중 비타민 E의 함량과 조직 의 지질과산화생성물의 농도와는 역의 관계를 나타냈고 적절한 식이비타민 E 의 첨가(30ppm)는 식이지방의 불포화도에 관계없이 조직의 지질과산화를 억제하는데 효과적임에 관찰되었다.