• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.12
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• pp.1322-1328
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• 2009

This paper presents vibration analysis of maskless exposure module in printed circuit board(PCB) manufacturing system. In order to complete exposure process in PCB, masking type module has been widely used in electronics industries. However, masking process confronts some limitations of application due to higher production cost for masking as well as lower printing resolution. Therefore, maskless exposure module is started to be in the spotlight for flexible production system to meet the needs of fabrication in variable patterns at low cost. Since maskless exposure process adopts direct patterning to PCB, vibration problems become more critical compared to conventional masking type process. Moreover, movements of exposure engine as well as stage generate vibration sources in the system. Thus, it is imperative to analyze the vibration characteristics for the maskless exposure module to improve the quality and accuracy of PCB. In this study, vibration analysis using the finite element analysis is conducted to identify the critical structural parts deteriorating vibration performance. Also, Experimental investigations are conducted by single/dual encoder measurement process under the operating module speed. Measurement points of vibration are selected by three places, which are base of stage, exposure engine and top of stage, to check the effect of vibration from the exposure engine. Comparisons between analysis results and experimental measurement are conducted to confirm the accuracy of analysis results including the developed FE model. Finally, this studies show feasibility of optimal design using the developed FE analysis model.

• Journal of Broadcast Engineering
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• v.22 no.3
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• pp.327-338
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• 2017

Exposure fusion is a typical image fusion technique to generate a high dynamic range image by combining two or more different exposure images. In this paper, we propose block-based exposure adjustment considering unique characteristics of human visual system and improved saturation measure to get weight map. Proposed exposure adjustment artificially corrects intensity values of each input images considering human visual system, efficiently preserving details in the result image of exposure fusion. The improved saturation measure is used to make a weight map that effectively reflects the saturation region in the input images. We show the superiority of the proposed algorithm through subjective image quality, MEF-SSIM, and execution time comparison with the conventional exposure fusion algorithm.

• Environmental Analysis Health and Toxicology
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• v.27
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• pp.5.1-5.10
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• 2012

Objectives: The purpose of this study was to assess the risk of ingestion exposure of lead by particle sizes of crumb rubber in artificial turf filling material with consideration of bioavailability. Methods: This study estimated the ingestion exposure by particle sizes (more than 250 um or less than 250 um) focusing on recyclable ethylene propylene diene monomer crumb rubber being used as artificial turf filling. Analysis on crumb rubber was conducted using body ingestion exposure estimate method in which total content test method, acid extraction method and digestion extraction method are reflected. Bioavailability which is a calibrating factor was reflected in ingestion exposure estimate method and applied in exposure assessment and risk assessment. Two methods using acid extraction and digestion extraction concentration were compared and evaluated. Results: As a result of the ingestion exposure of crumb rubber material, the average lead exposure amount to the digestion extraction result among crumb rubber was calculated to be $1.56{\times}10^{-4}$ mg/kg-day for low grade elementary school students and $4.87{\times}10^{-5}$ mg/kg-day for middle and high school students in 250 um or less particle size, and that to the acid extraction result was higher than the digestion extraction result. Results of digestion extraction and acid extraction showed that the hazard quotient was estimated by about over 2 times more in particle size of lower than 250 um than in higher than 250 um. There was a case of an elementary school student in which the hazard quotient exceeded 0.1. Conclusions: Results of this study confirm that the exposure of lead ingestion and risk level increases as the particle size of crumb rubber gets smaller.

• Journal of Radiation Industry
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• v.11 no.1
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• pp.47-54
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• 2017

Compared to other occupations, there is a greater risk of exposure to radiation due to the use of radioisotopes in nuclear medicine for diagnostic evaluations and therapy. To consider ways to reduce exposure dose for those in nuclear medicine involved in injection work and elution work among radiation workers as well as for sanitation workers and trainees among frequent workers an investigation into exposure dose and situational analysis from changes in yearly exposure dose evaluations, changes in work environment and changes in forms of inspection were conducted. Exposure dose measurements were taken by using EPD MK2 worn during working hours for one injection worker, one elution worker, two sanitation workers, and one trainee at a general hospital in the Seoul area for three days from July 18th to 20th 2016. Radiation from radioisotopes which are a part of nuclear medicine can significantly affect not only radiation workers who deal with radioisotopes directly but also frequency works as well. According to this study the annual dose limit for elution workers and injection workers were considered safe as the amount of exposure was not large enough to have a significant effect. The limits of this study consist in the duration of this study and the quantity of participants. Also there was a limitation of the measurement device involving accumulated exposure, where the EPD MK2 cannot check the changes in exposure according to a particular activity.

• Journal of Biomedical Engineering Research
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• v.39 no.6
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• pp.243-249
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• 2018

The indoor radon concentration was measured in the lecture room of the university and the radon concentration was converted to the amount related to the radon exposure using the dose conversion convention and compared with the reference levels for the radon concentration control. The effect of indoor radon inhalation was evaluated by estimating the life effective dose and the risk of exposure. To measure the radon concentration, measurements were made with a radon meter and a dedicated analysis Capture Ver. 5.5 program in a university lecture room from January to February 2018. The radon concentration measurement was carried out for 5 consecutive hours for 24 hours after keeping the airtight condition for 12 hours before the measurement. Radon exposure risk was calculated using the radon dose and dose conversion factor. Indoor radon concentration, radon exposure risk, and annual effective dose were found within the 95% confidence interval as the minimum and maximum boundary ranges. The radon concentration in the lecture room was $43.1-79.1Bq/m^3$, and the maximum boundary range within the 95% confidence interval was $77.7Bq/m^3$. The annual effective dose was estimated to be 0.20-0.36 mSv/y (mean 0.28 mSv/y). The life-time effective dose was estimated to be 0.66-1.18 mSv (mean $0.93{\pm}0.08mSv$). Life effective doses were estimated to be 0.88-0.99 mSv and radon exposure risk was estimated to be 12.4 out of 10.9 per 100,000. Radon concentration was measured, dose effective dose was evaluated using dose conversion convention, and degree of health hazard by indoor radon exposure was evaluated by predicting radon exposure risk using nominal hazard coefficient. It was concluded that indoor living environment could be applied to other specific exposure situations.

• Journal of Environmental Health Sciences
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• v.45 no.4
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• pp.358-369
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• 2019

Objective: This study aimed to introduce cases of exposure to humidifier disinfectant (HD) in hospitals and to present their exposure characteristics. Methods: We used data from 4,393 subjects who participated in the fourth assessment survey of environmental exposure to HD conducted by the Korea Environmental Industry & Technology Institute. In this study, we selected 301 subjects who reported their place of use of HD as a hospital. Then, we classified cases as 'Hospital-provided'. 'Probably hospital-provided', 'Individual purchased', and 'Unknown' according to the supply sources of HD. Also, we introduced detailed exposure characteristics for the selected cases. Results: Of the 4,393 subjects, 301 (6.9%) reported the use of HD in 392 hospitals (including duplicate answers for the use in ${\geq}2$ hospitals). The 301 hospital-user subjects included 139 survivors and 162 non-survivors. When we classified the 392 cases by supply sources, 'Hospital-provided' was 12.2% (48 cases), 'Probably hospital-provided' was 25.5% (100 cases), 'Individual purchased' was 59.7% (234 cases), and 'Unknown' was 2.6% (10 cases). Among the 'Hospital-provided' cases, we selected six cases and provided a detailed description of the HD use in this study. Additionally, we reported details for six cases that had purchased HD upon a doctor or nurse's recommendation and for three cases that had purchased it at hospital stores. Conclusion: This study presents various cases of HD exposure in hospitals. Because there may be a considerable burden of HD exposure in public spaces, including hospitals, further studies are necessary to assess HD exposure in hospitals and public places.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.1
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• pp.1-12
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• 2019

Objective: Significant concerns have been raised over chemical exposure and potential health risks such as increased cancer mortality among laboratory workers. The aim of this study was to investigate the overall exposure and unit task exposure levels of researchers in organic synthesis laboratories at universities. Methods: Seventy-seven personal Time-weighted average(TWA) samples and 139 task-based samples from four organic synthesis laboratories at two universities were collected over three days. The concentrations of acetone, chloroform, dichloromethane(DCM), diethyl ether, ethyl acetate, n-hexane, tetrahydrofuran(THF), benzene, toluene, and xylene were determined using the GC-FID. Results: The most frequently used chemicals in the laboratories were acetone, DCM, n-hexane, methanol, and THF. Carcinogens such as benzene, chloroform, and DCM were used in one or more laboratories. The TWA full-shift exposures of researchers to acetone was the highest(ND-59.3 ppm). Benzene was observed above the occupational exposure limit in 18-40% of the samples. The levels of exposure to organic solvents were statistically different by task(p<0.05), while washing task was the highest. Washing was not perceived as a part of the real lab tasks. Rather it was considered as simple dish-washing or experimental preparation and performed in an open sink where exposure to organic solvents was unavoidable. TWAs and task-based concentrations were compared by substance, which suggests that TWA-based assessment could not reflect short-term and high concentration exposures. Conclusions: Laboratory workers may be exposed to various organic solvents at levels of concern. TWA-based measurement alone cannot guarantee holistic exposure assessment among lab workers as their exposures are very dependent on their tasks. Further investigation and characterization for specific tasks and overall chronic exposures will help protect lab workers from unnecessary exposure to chemicals while they perform research.

• Safety and Health at Work
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• v.12 no.2
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• pp.238-243
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• 2021

Objectives: The aim of this study was to provide baseline data for the assessment of exposure to indium and to prevent adverse health effects among workers engaged in the electronics and related industries in Republic of Korea. Methods: Total (n = 369) and respirable (n = 384) indium concentrations were monitored using personal air sampling in workers at the following 19 workplaces: six sputtering target manufacturing companies, four manufacturing companies of panel displays, two companies engaged in cleaning of sputtering components, two companies dedicated to the cleaning of sputtering target, and five indium recycling companies. Results: The level of exposure to total indium ranged from 0.9 to 609.3 ㎍/m³ for the sputtering target companies; from 0.2 to 2,782.0 ㎍/m³ for the panel display companies and from 0.5 to 2,089.9 ㎍/m³ for the indium recycling companies. The level of exposure to respirable indium was in the range of 0.02 to 448.6 ㎍/m³ for the sputtering target companies; 0.01 to 419.5 ㎍/m³ for the panel display companies; and 0.5 to 436.3 ㎍/m³ for the indium recycling companies. The indium recycling companies had the most samples exceeding the exposure standard for indium, followed by sputtering target companies and panel display companies. Conclusions: The main finding from this exposure assessment is that many workers who handle indium compounds in the electronics industry are exposed to indium levels that exceed the exposure standards for indium. Hence, it is necessary to continuously monitor the indium exposure of this workforce and take measures to reduce its exposure levels.

• Health Policy and Management
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• v.30 no.4
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• pp.505-512
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• 2020

Background: In monitoring exposure to environmental smoke (ETS), biomarkers can overcome the subjectivity and inaccuracy of self-reporting measurements, and have the advantage of reflecting ETS exposure in all places. This study aims to evaluate the effectiveness of ETS exposure measurement using biomarkers such as urine cotinine. Methods: This study used the Korea National Health and Nutrition Survey data from 2009 to 2018. A total of 28,574 non-smokers with urine cotinine data were selected for the study. The cotinine concentration and ETS exposure rate using urine cotinine was estimated and then compared with the self-reporting measurements. The degree of agreement among measurements of ETS exposure was confirmed. Results: As a result of measuring ETS exposure with urine cotinine, 23,594 (83.8%) out of 28,574 subjects were classified as to exposure groups. This estimate differs significantly from measurements made by self-reporting. In addition, the average concentration of cotinine in non-smokers has decreased to a 10th level over the past 10 years. Based on the biomarker, the sensitivity of the self-reporting was 8.5%-29.0%, the specificity was 16.4%-19.5%, and the kappa value was 2.0%-5.8%. Conclusion: The findings of our study show that self-reporting measurement does not well reflect the extent to which non-smoker's exposure to smoking materials. Whereas cotinine concentration has decreased significantly over the past 10 years, the ETS exposure rate has not reduced. It strongly suggests the need for intervention in the group of non-smokers exposed to low concentrations of smoke. Therefore, an assessment using biomarkers such as cotinine-based measurement should be made in the Health Plan 2030.

• Safety and Health at Work
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• v.11 no.4
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• pp.509-516
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• 2020

Background: Meta-analyses have shown firefighters to be at an increased risk of several cancer types. Occupational carcinogen exposure may explain these increased risks. This study aims to describe Norwegian fire departments' work conditions from 1950 until today, focusing on factors relevant for potential occupational carcinogen exposure. Methods: With the help of a reference group, we developed a questionnaire on topics related to occupational exposure to carcinogens for the period 1950-2018. Selected Norwegian fire departments provided department-specific responses. Results: Sixteen departments, providing fire services for 48% of the Norwegian population as of 2019 and mainly consisting of professional firefighters, responded to our questionnaire. The introduction of synthetic firefighting foams, more regular live fire training, the introduction of chemical diving, and a higher number of diesel-driven fire service vehicles were identified as changes thought to increase exposure to occupational carcinogens. Changes thought to decrease exposure included the switch from negative to positive pressure self-contained breathing apparatuses, the use of self-contained breathing apparatuses during all phases of firefighting, the use of ventilating fans during firefighting, increased attention to flammable materials used during live fire training, increased attention to handling and cleaning of turnout gear and other equipment, and installment of exhaust removal systems in apparatus bays. Conclusion: Norwegian fire departments' work conditions have seen several changes since 1950, and this could influence firefighters' occupational carcinogen exposure. A peak of carcinogen exposure may have occurred in the 1970s and 1980s before recent changes have reduced exposure.