• Applied Chemistry for Engineering
• /
• v.25 no.1
• /
• pp.41-46
• /
• 2014

The property improvement of polycarbonate coated with a multilayer film composed of an inorganic $SiO_2$ film and a photocatalytic $TiO_2$ film was studied. The $SiO_2$ film as a binder had an excellent light transmission characteristic. After the treatment with atmospheric pressure plasma, the surface of $SiO_2$ film showed the hydrophilicity, which increased the film coating uniformity with a $TiO_2$-containing aqueous solution. When $TiO_2$ film was over 200 nm thick, the absorption effect of UV rays in the range of 180~400 nm suppressed the yellowing phenomena of polycarbonate substrate. The inorganic film improved the heat resistance of polycarbonate substrates. $TiO_2$ film in the outmost under the exposure of UV rays promotes the catalytic oxidation characteristics and yields the capability to the decomposition of organic contaminants, and also increases the self-cleaning properties due to the increase of hydrophilicity. Structural stability of the polycarbonate substrate coated with inorganic $TiO_2$ and $SiO_2$ film was shown. The role of $SiO_2$ film between $TiO_2$ and polycarbonate substrate suppressed the peeling of $TiO_2$ film by inhibiting the photocatalytic oxidation effect of $TiO_2$ film on the polycarbonate substrate.

• Food Engineering Progress
• /
• v.13 no.3
• /
• pp.211-215
• /
• 2009

Concentrations of benzo[$\alpha$]pyrene in edible oils from Korean market were evaluated by high performance liquid chromatography. Benzo[$\alpha$]pyrene known of the carcinogenic polycyclic aromatic hydrocarbons(PAHs), has been found at variable concentrations in several foods. This is associated with several factors during the process including contaminated raw materials, exposure of environment, and procedure of process or cooking. The levels of benzo[$\alpha$]pyrene were ranged from 0.5 to 1.4 $\mu$g/kg in virgin olive oil. Benzo[$\alpha$]pyrene contents in refined and virgin olive oil, sesame oil, soybean oil, corn oil, sunflower oil, safflower oil, and processed oil were 0.6-1.0 $\mu$g/kg, 0.9-1.3 $\mu$g/kg, 0.6-3.3 $\mu$g/kg, 0.5-1.1 $\mu$g/kg, 1.2-1.7 $\mu$g/kg, 1.0-2.1 $\mu$g/kg, and 1.0-1.4 $\mu$g/kg, respectively.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.29 no.3
• /
• pp.289-297
• /
• 2019

Objectives: To identify the positive rate of and the risk factors associated with latent tuberculosis infection(LTBI) in mine workers, the objectives of the present study evaluated those among former mine workers. Methods: Between January 2015 and May 2017, former male mine workers who had been subjects for epidemiology research for work-related chronic obstructive pulmonary disease(COPD) and had received QuantiFERON-$TB^{(R)}$ Gold In-Tube(QFT-GIT) from the Institute of Occupation and Environment(IOE) under Korea Workers' Compensation and Welfare Service(KCOMWEL) were selected as the study subjects. To identify significant variables for increased risk of LTBI, logistic regression analysis was performed. Results: A total of 736 male former mine workers were selected as study subjects. The positive rate of LTBI among subjects was 69.2%(509/736). The current smoking[odds ratio(OR), 2.3; 95% confidence interval(CI), 1.1-4.9], COPD(OR, 1.4; 95% CI, 0.9-2.3), department loading(OR, 1.8; 95% CI, 0.9-3.4) and mining(OR, 1.5; 95% CI, 0.9-2.5), and working duration of over 20(OR, 1.6; 95% CI, 0.9-3.1) and over 30 years(OR, 2.2; 95% CI, 0.9-4.9) were associated with increased risk of LTBI. The interferon-gamma(IFN-${\gamma}$) level after stimulation with Mycobacterium tuberculosis(MTB)-specific antigens showed a significantly negative correlation with age(r=-0.126). Conclusions: The present study determined that the high positive rate of LTBI among mine workers was associated with not only the host factors but also the occupational exposure to mine dust.

• Applied Chemistry for Engineering
• /
• v.29 no.6
• /
• pp.670-676
• /
• 2018

Experiments on combustion gases generation of untreated cypress specimens or treated with boric acid, ammonium pentaborate, and boric acid/ammonium pentaborate additive were carried out. Test specimens were painted three times with 15 wt% boron compound aqueous solutions. After drying, the generation of combustion gas was analyzed using a cone calorimeter (ISO 5660-1). As a result, comparing to untreated specimen, the smoke performance index (SPI) of the specimens treated with the boron compound increased by 1.37 to 2.68 times and the smoke growth index (SGI) decreased by 29.4 to 52.9%. The smoke intensity (SI) of the specimens treated with boron compounds is expected to be 1.16 to 3.92 times lower than that of untreated specimens, resulting in lower smoke and fire hazards. Also, the maximum carbon monoxide ($CO_{peak}$) concentration of specimens treated with boron compounds was 12.7 to 30.9% lower than that of untreated specimens. However, it was measured to produce fatal toxicities from 1.52 to 1.92 times higher than that of permissible exposure limits (PEL) by Occupational Safety and Health Administration (OSHA). The boron compounds played a role in reducing carbon monoxide, but it did not meet the expectation of reduction effect because of the high concentration of carbon monoxide in cypress itself.

• The Journal of the Convergence on Culture Technology
• /
• v.5 no.3
• /
• pp.345-349
• /
• 2019

In Korea, the mountainous area occupies more than 70% of the whole country, cutting of earth slope that cuts a part of the ground surface is widely used when building infrastructures such as road, railroad, and industrial complex construction. In recent years, regulations on environmental damage have become more strict, and various methods have been developed and applied. Among them, Concrete-Panel Retaining Wall technique is actively applied. Concrete-Panel Retaining Wall is a method to resist horizontal earth pressure by forming a wall by attaching a precast retaining wall to the front of the support material and increasing the shear strength of the disk through reinforcement of the support material. Soil nailing, earth bolt, and ground anchor are used as support material. Among them, ground anchor is a more aggressive reinforcement type that introduces tensile load in advance to the steel wire, and a large concentrated load acts on the front panel. This concentrated load is a factor that creates cracks in the concrete panel and reduces the durability of the retaining wall itself. In this study, steel pipe sleeves and reinforcements were purchased at the anchorage of the panel to prevent cracks, and by applying bumpy shear keys to the end of the panel, the weakness of the individual behavior of the existing grout anchors was improved. The problem of degraded landscape by exposure to front concrete of retaining wall and protrusion of anchorage was solved by the production of natural stone patterns and the construction of sections that do not protrude the anchorage. In order to verify the effectiveness of anti-crack sleeves and reinforcements used in the null, indoor testing and three-dimensional numerical analysis have been performed, and the use of steel pipe sleeves and reinforcements has demonstrated the overall strength increase and crack suppression effect of panels.

• Journal of the Korean Society of Radiology
• /
• v.13 no.1
• /
• pp.141-146
• /
• 2019

Radiation sources used in the field of industrial non-destructive pose a risk of exposure due to ageing equipment and operator carelessness. Thus, the need for a safety management system to trace the location of the source is being added. In this study, Monte Carlo Simulation was performed to analyse the angle dependence of the unit-cell comprising the line-array dosimeter for tracking the location of radiation sources. As a result, the margin of error for the top 10% of each slope was 5.90% at $0^{\circ}$, 8.08% at $30^{\circ}$, and 20.90% at $60^{\circ}$. The ratio of the total absorbed dose was 83.77% at $30^{\circ}$ and 53.36% at $60^{\circ}$ based on $0^{\circ}$(100%) and showed a tendency to decrease with increasing slope. For all gradients, the maximum number was shown at $30^{\circ}$ No. 9 pixels, and for No. 10, there was a tendency to drop 7.24 percent. This study has shown a large amount of angle dependence, and it is estimated that the proper distance between the source and line-array dosimeters should be maintained at a distance of not less than 1 cm to reduce them.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.31 no.2
• /
• pp.173-183
• /
• 2021

Objectives: This study evaluated the skin permeability of lawsone in henna hair dyes to understand the exposure characteristics of henna hair dyes in the human body. It examined the protective effects of protectants by applying protectants A, B, and C to test skin. Methods: Skin absorption tests were conducted using Franz diffusion cells according to OECD test guideline 428. After applying one kind of natural henna hair dye and chemical henna hair dye, respectively, to a standardized pig skin model, samples of receptor fluid were collected at 1h, 3h, 6h, and 24h. The skin permeation of lawsone was determined using HPLC. After the skin absorption experiment, the skin to which hair dye was applied was analyzed to determine the residual amount of lawsone in the skin. Results: The cumulative permeation of both natural and chemical henna hair dyes increased over time, and the natural henna hair dye had a flux value (t=3.194, p<.05) high both in the K_p value (t=3.207, p<.05) and the residual amount (t=22.701, p<.001). For skin treated with a protectant, the cumulative permeation of natural henna hair dye 24h control and the cumulative permeation of protectant A, B, and C increased over time. Flux and K_p values were in the order control > protectant A > protectant C > protectant B. The residual amount (F=4.469, p<.05) was in the order of protectant C > protectant A > protectant B > control. At 3h, the dye application time of natural henna hair dye, the lawsone flux value (F=4.454, p<.05) and K_p value (F=4.455, p<.05) were higher in the control group than in the protectant groups. The 24h cumulative permeation of the chemical henna hair dye increased with time in both the control and the protectant groups, and the flux and K_p values were in the order of protectant A > protectant C > protectant B > control. The residual amount (F=7.901, p<.01) was in the order of protectant B > protectant A> protectant C > control. Conclusions: Within the normal dyeing time for henna hair dye (three hours for natural henna hair dyes and 30 minutes for chemical henna hair dyes) lawsone skin penetration was not observed even when no protective agent was applied. After that time, however, evidence of skin penetration and retention of lawsone and the protective effect of protective agents were observed.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.31 no.1
• /
• pp.73-82
• /
• 2021

Objectives: This study aimed to investigate the public cognition and information acquisition route for heavy metals and organic solvents in the general population in order to provide information for the development of public relations materials. Methods: The study was carried out by questionnaire from January to March 2011 by an interview with trained surveyors. There were 700 participants, divided by gender and age. A questionnaire was issued consisting of subjective and objective cognition evaluation items and questions about information acquisition route and preferred information acquisition route for six heavy metals and five organic solvents. Data were expressed as a percentage using the SPSS 23.0 software package. Result: For heavy metals, subjective and objective cognition degrees were higher in the order of lead, mercury, cadmium, and arsenic. They were higher among males than females, and in adults compared to school-age subjects. For organic solvents, both cognition degrees were high in the order of acetone, benzene, and formaldehyde. However, cognition degree by gender and age showed a complex pattern. As a response to information acquisition route, broadcast media had the highest in all ages and genders, followed by word of mouth from neighbors in elementary school children, school education or expert lectures in middle and high school students up to people in their 30s, and print media among those in their 40s to over 60s. There was no difference in the order by gender. As a response to preference for information acquisition route, broadcast media also proved the highest in all ages and genders, followed by school education or professional lectures among those in elementary school and over their 60s, and the internet in other age groups. Females preferred school education or expert lectures and word of mouth from neighbors, while males preferred the internet. In the case of the internet, the ranking was higher for preferred information acquisition route compared with the ranking for information acquisition route. Conclusions: This data on cognition degree, information acquisition route, and preferred information acquisition route according to gender and age can provide basic data for the development of educational and promotional materials for heavy metals and organic solvents exposure management.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.31 no.2
• /
• pp.138-146
• /
• 2021

Objectives: This study aims to compare and evaluate the reduction efficiency of disinfectants used in the domestic meat processing industry to reduce bioaerosol exposure of meat industry workers and to use this as basic data for establishing work environment management measures. Methods: Thirteen disinfectants sold in South Korea were selected for evaluation and the bacterial reduction effect of the disinfectants was investigated. Bacterial suspension and surface disinfection tests were conducted to compare and analyze the antibacterial strength of the disinfectants. Pork carcasses, cutting boards, benches, and conveyor belts were selected for surface sterilization tests. Results: As a result of the bacterial suspension experiment test, all disinfectants had a bacterial reduction efficiency of more than 86%. Among them, the bacterial reduction efficiency of chlorine disinfectants was 99.93% on average. In the results of the pork carcass surface sterilization test, the rate of reduction of disinfectants made of quaternary ammonium compounds (QACs) was the highest. Tests of plastic cutting boards showed that chlorine disinfectants had the best sterilization effect. Experiments on stainless steel benches showed the best bacterial reduction efficiency for chlorine dioxide and QACs disinfectants. In the conveyor belt made of urethane, QACs disinfectants showed excellent sterilization effects. Conclusions: The study evaluated the disinfection power of disinfectants against bacteria occurring in domestic meat processing plants. All disinfectants were found to be effective in bacterial suspension experiments, and chlorine disinfectants were particularly effective. In surface sterilization experiments, sterilizing agents with QACs as the main ingredient were excellent.

• Journal of the Korean Society of Radiology
• /
• v.14 no.7
• /
• pp.899-906
• /
• 2020

The WSS lateral examination is important for diagnosing spinal disorders. Recently, long-length detectors for large-area diagnose have been popularized to effectively reduce the exposure dose and examination time. It can be applied very efficiently to examinations of patients with high risk of falls, children, and adolescents. However, since the image is acquired through a single irradiation, the volume of cervical vertebra is relatively smaller than the lumbar due to the geometrical anatomy of the spine. Therefore, this study intends to fabricate an additional filter using 3D printing technology and copper filament to obtain uniform image quality in the WSS lateral examination and to analyze the results. 3D printing technology is able to easily print a desired shape, so it is widely used in the entire industrial field, and recently, a copper filament has been developed to confirm the possibility as an additional filter. In the WSS lateral examination, CNR and SNR were excellently measured when the additional filter was applied, confirming the possibility of using the additional filter.