• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.3
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• pp.213-232
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• 2009

This document was prepared to review and summarize the analytical methods for airborne and bulk asbestos. Basic principles, shortcomings and advantages for asbestos analytical instruments using phase contrast microscopy(PCM), polarized light microscopy(PLM), X-ray diffractometer (XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM) were reviewed. Both PCM and PLM are principal instrument for airborne and bulk asbestos analysis, respectively. If needed, analytical electron microscopy is employed to confirm asbestos identification. PCM is used originally for workplace airborne asbestos fiber and its application has been expanded to measure airborne fiber. Shortcoming of PCM is that it cannot differentiate true asbestos from non asbestos fiber form and its low resolution limit ($0.2{\sim}0.25{\mu}m$). The measurement of airborne asbestos fiber can be performed by EPA's Asbestos Hazard Emergency Response Act (AHERA) method, World Health Organization (WHO) method, International Standard Organization (ISO) 10312 method, Japan's Environmental Asbestos Monitoring method, and Standard method of Indoor Air Quality of Korea. The measurement of airborne asbestos fiber in workplace can be performed by National Institute for Occupational Safety and Health (NIOSH) 7400 method, NIOSH 7402 method, Occupational Safety and Health Administration (OSHA) ID-160 method, UK's Health and Safety Executive(HSE) Methods for the determination of hazardous substances (MDHS) 39/4 method and Korea Occupational Safety and Health Agency (KOSHA) CODE-A-1-2004 method of Korea. To analyze the bulk asbestos, stereo microscope (SM) and PLM is required by EPA -600/R-93/116 method. Most bulk asbestos can be identified by SM and PLM but one limitation of PLM is that it can not see very thin fiber (i.e., < $0.25{\mu}m$). Bulk asbestos analytical methods, including EPA-600/M4-82-020, EPA-600/R-93/116, OSHA ID-191, Laboratory approval program of New York were reviewed. Also, analytical methods for asbestos in soil, dust, water were briefly discussed. Analytical electron microscope, a transmission electron microscope equipped with selected area electron diffraction (SAED) and energy dispersive X-ray analyser(EDXA), has been known to be better to identify asbestiform than scanning electron microscope(SEM). Though there is no standard SEM procedures, SEM is known to be more suitable to analyze long, thin fiber and more cost-effective. Field emission scanning electron microscope (FE-SEM) imaging protocol was developed to identify asbestos fiber. Although many asbestos analytical methods are available, there is no method that can be applied to all type of samples. In order to detect asbestos with confidence, all advantages and disadvantages of each instrument and method for given sample should be considered.

• Korean Security Journal
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• no.19
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• pp.23-41
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• 2009

The purpose of this study is to investigate about security service history on 1930s in Korea. This study used materials by historical facts for the regulations, books and newspapers in 1930s. In 1930s, security service was unknown details of the historical contents so far. There are four parts conclusion of this study: police department of provisional government, security service agency in the provisional government, security service agents of an independence movement, the general society of Korea. Firstly, Korean regional government in Manchuria, which Kokminbu(國民府) organized the security service agency(警護局) for protect government and public security. Most importantly, the security service agency appearanced an important place which were the independence movement and self-governing administration for Koreans in Manchuria. And the security service agency was required by the security service regulations(警護條例) as law. Secondly, diversity activities of security service in police were exposed the duty as 'car escort service(車輛警護)' for offenders, the 'township office guard' from mobsters, 'woodland protect service(林野警護團)' for fire-raisers. security service as police officer were widely application for protection and safety from danger. Thirdly, Mass society was needed to service for public security in daily events such as 'noted singer meeting', 'funeral procession to the graveyard', 'athletic meeting' as private establishment of security service agency in nowadays. people were wanted the private security service(私警護) from 1930s to present. Fourthly, Overseas security service mentioned in attack of politician, protect from poison and security service about train vessel fleet. In 1930s, security service is comprehensive protection which were not only bodyguard, but also safeguard for hazardous materials.

• Journal of Korea Soil Environment Society
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• v.1 no.1
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• pp.67-79
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• 1996

Clay soils typically have low hydraulic conductivities in the presence of high polarity pore fluid, such as water. Low polarity fluids, such as hydrocarbon fuels and halogenated organic solvents, typically cannot migrate into clay pores because they cannot displace the pore water. Oxygenated additives in gasoline, such as alcohols and methyl-tert-butyl ether, are increasingly used to control air pollution emissions. These relatively polar and highly water-soluble compounds may facilitate displacement of pore water and enhance migration of fuels and solvents through clay-rich soil strata. In the reported research, the migration of gasoline-alcohol fuel mixtures (gasohol) through consolidated clay was examined. Prepared kaolinite clay samples were consolidated from slurry, and various combinations of gasoline, alcohol, and water were applied to the clays under 152 Pa gauge pressure. Movement of the fluids into the clay samples was monitored by measur ing displaced pore fluid and by magnetic resonance imaging of the samples. The structures of selected samples were examined using environmental scanning electron microscopy. Results of the research suggest that alcohol added to hydrocarbon fuels can enhance migration through some clays significantly. Gasoline did not migrate appreciably into water saturated clay, even after 14 days under pressure. The gasohol mixture migrated readily into the clay in only 20 minutes. Increased hydraulic conductivity of the clay in the presence of gasohol is hypothesized to be due to the collapse of the clays pore structure when ethanol is present, creating larger pores. Increasing pore diameter decreases the capillary pressure needed for the gasohol to replace water and allows gasohol to migrate through the clay.

• Journal of Food Hygiene and Safety
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• v.35 no.2
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• pp.162-169
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• 2020

This study was conducted to survey levels of heavy metals, benzopyrene and mycotoxins in teas purchased from online markets, supermarkets, and traditional markets in Gwangju, Korea. We examined the arsenic, cadmium and lead content in heavy metals. We also tested for benzo(a)pyrene, which is classified as a carcinogen. In addition, we tested for the mycotoxins aflatoxin (AFB₁, AFB₂, AFG₁, AFG₂), ochratoxin A (OTA), fumonisin (FUB₁, FUB₂), and zearalenone (ZON). According to our results, heavy metals were detected within the allowable range (below 5.0 mg/kg for lead) and all samples met with the standards for tea as presented in the Korean Food Code. The Benzo(a)pyrene showed a detection rate of 12.8% in 16 of 125 samples and mycotoxins showed 23.2% in 29 of 125 samples. However, safe levels regarding benzo(a)pyrene and mycotoxin in tea were not ascertainable since the standards are not set in the Korean Food Code.

• Fire Science and Engineering
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• v.25 no.3
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• pp.113-118
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• 2011

The flash point is an important indicator of the flammability of a chemical. The minimum flash point behaviour (MFPB) is exhibited when the flash point of a mixture is below the flash points of the individual components. The identification of this behaviour is critical, because a hazardous situation results from taking the lowest component flash point value as the mixture flash point. In this study, the flash points for the n-butanol + n-decane and n-octane + n-propanol systems which exhibit MFPB, were measured by Tag open-cup apparatus. The experimental data were compared with the alues calculated by the Raoult's law, the van Laar equation and the Wilson equation. The calculated values based on the van Laar and Wilson equations were found to be better than those based on the Raoult's law. It was concluded that the van Laar and Wilson equations were more effective than the Raoult' law at describing the activity coefficients for non-ideal solution such as the n-butanol + n-decane and n-octane + n-propanol systems. The predictive curve of the flash point prediction model based on the Wilson equation described the experimentally-derived data more effectively than was the case when the prediction model was based upon the van Laar equation.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.221-228
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• 2004

Basic properties of artificial lightweight aggregate by using waste dusts and strength properties of LWA concrete were studied. Bulk specific gravity and water absorption of artificial lightweight aggregates varied from 1.4 to 1.7 and 13 to 16%, respectively. Crushing ratio of artificial lightweight aggregate was above 10% higher than that of crushed stone or gravel. As a result of TCLP leaching test, the leaching amount of tested heavy metal element was below the leaching standard of hazardous material. Slump, compressive strength and stress-strain properties of LWA concrete made of artificial lightweight aggregate were tested. Concrete samples derived from LWA substitution ratio of 30 vol% and W/C ratio of 45 wt% showed the best properties overall. Thermal insulation and sound insulation characteristics of light weight concrete panel with the optimum concrete proportion were tested. Average overall heat transmission of 3.293W/㎡$^{\circ}C$ was observed. It was higher by about 15% than those of normal concrete made by crushed stone. Sound transmission loss of 50.9 ㏈ in frequency of 500 ㎐ was observed. It was higher by about 13% than standard transmission loss.

• Journal of the Korean Data and Information Science Society
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• v.28 no.6
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• pp.1337-1348
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• 2017

In this paper, we develop the high-risk drinking predictive model in Korea using the cross-sectional data from Korea Community Health Survey (2014). We perform the logistic regression analysis, the decision tree analysis, and the neural network analysis using the data mining technique. The results of logistic regression analysis showed that men in their forties had a high risk and the risk of office workers and sales workers were high. Especially, current smokers had higher risk of high-risk drinking. Neural network analysis and logistic regression were the most significant in terms of AUROC (area under a receiver operation characteristic curve) among the three models. The high-risk drinking predictive model developed in this study and the selection method of the high-risk intensive drinking group can be the basis for providing more effective health care services such as hazardous drinking prevention education, and improvement of drinking program.

• Journal of Technologic Dentistry
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• v.22 no.1
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• pp.89-112
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• 2000

Although dental laboratory technicians are prone to be exposed to various work-related health hazardous materials such as dusts, chemicals, etc., the prevalence and nature of work-related health problems of them have not been a matter of great concern in the field of occupational health service in Korea. The purpose of the present investigation was to describe a collected profile of subjective health symptoms and their attributable factors in Korean dental laboratory technicians. A questionnaire listing five groups of health symptoms and five health symptom-related factors was mailed to randomly selected 1,900 dental laboratory technicians. Among them, 1,344 dental laboratory technicians filled out the questionnaires and returnde them. Five groups of health symptoms included musculoskeletal symptom, dermal symptoms, respiratory symptoms, eys symptoms, and ear symptoms. Five health symptom-related factors were occupational environment-related health risk factors, work history, health related habits and status, use of personal protective equipment and general characteristics. Detailed parameters of health risk factors were work posture, vibration, and chemical or physical hazards such as dust, fume, vapor, solvent, light, and noise for occupational environment-related factors; work place, area, number of employees, work hours, career, work part, and work load for work history; Broca's index, hours of sleep, eating, smoking, alcohol, exercise, health examination, and self assessed health status for health habits and status; face masks, goggles, and so on for use of personal protective equipment, and; age, sex, marital status, and education for general characteristics. Before the start of main survey, a pilot survey was carried out for validity and reliability tests of the questionnaire. All the data obtained were coded and analyzed with PC/SAS 6.12 program. The prevalence of health symptoms was the highest in musculoskelton (87.3%), and followde by eyes (78.9%), respiratory organs (64.3%), ears (57.8%), and skin (52.2%) in descending order. Statistically significant risk factors by multiple logistic regression analyses were sex, health examination, self assessed health status, and hand/finger posture in musculoskeletal symptoms; sex, self assessed health status, career, acid gas, and hand contact with resin mixture in deraml symptoms; Broka's smoking, exercise, self assessed health status, and face mask in respiratory symptoms; sex, hours of sleep, self assessed health status, work hours, work load, plaster dust, inadequate lighting, and goggle in eys symptoms, and eating, smoking, self assessed health status, and work load in ear symptoms. With the above considerations in mind, prevalence of subjective symptoms among Korean dental laboratory technicians was relatively high, and they were attributable to most of the occupational environment-related factors, work history, use of personal protective equipment, health habits and status, and general characteristics. Particularly, it is suggested that health promotion programs for promoting self- assessed health status and smoking cessation, preventive measures for protection of the female technicians’health, and reducing work load be necessary, since those factors were associated with more than one subjective symptom.

• Journal of Environmental Health Sciences
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• v.20 no.1
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• pp.62-67
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• 1994

Introduction : Recently, water and environmental pollution becomes serious social problem and high technology makes this pollution accelerate. Hydrogen sulfide, the main subject of our research, is one of the most dangerous air pollutant like SO$_x$ and NO$_x$. The major contaminant in coal gasification is H$_2$S, which is very toxic, hazardous and extremely corrosive. Therefore, control of hydrogen sulfide to a safe level is essential. Although commercial desulfurization process called liquid scrubbing is effective for removal of H$_2$S, it has drawbacks, the loss of sensible heat of the gas and costly wastewater treatment. Many investigations are carried out about high-temperature removal ol H$_2$S in hot coal-derived gas using metal oxide or mixed metal qxide sorbents. It was reported that ZnO was very effective sorbent for H2S removal, but it has big flaw to vaporize elemental zinc above 600\ulcorner \ulcorner As alternative, metal oxides such as CaO, $Fe_2O_3$, TiO$_2$ and CuO were added to ZnO. Especially, different results are reported for $Fe_2O_3$ additive. Tamhankar et al. reported SiO$_2$ with 45 wt% $Fe_2O_3$ sorbent is favorable for removal of H$_2$S and regeneration.

• Journal of Environmental Policy
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• v.4 no.2
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• pp.57-82
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• 2005

In this study, we propose methods for. the efficient management and integrity of groundwater in response to a diminishing supply. As an alternative water resource for the future. we investigated and comparatively analyzed the quality standards of groundwater in the US (New York, Wisconsin and Texas), Austria, Netherlands, Canada, Japan and United Kingdom. These developed countries heavily depend on groundwater, more than 70%, for drinking water and apply those drinking water standards to groundwater quality. However, there exists few differences in the quality standards of groundwater among the countries, because each country possesses its own individual environment and management. In Korea, surface water pollution is getting serious and its water resources are diminishing. Therefore we propose several new quality criteria that many countries regulate at these days for their efficient management of groundwater. There is a need to divide BTEX criterion into Benzene, Toluene, Ethylbenzene and Xylene, individually. In. addition, it is needed to establish BTEX criteria into agricultural water and industrial water use standards as well as daily life use standards. Also, regulations for some PAHs, showing carcinogenicity, are required. Due to rapid industrialization various hazardous chemicals were utilized and their uses are increasing each year. Therefore, there is a strong need to introduce n~w standards and tighter regulations of the levels. At the same time, the criterion of nitrogenous compounds need' to be regulated individually in order to prevent the damage incurred by the compounds. Several developed countries have established standards for radon, previously caused environmental accidents in Korea. Therefore, we propose the necessity of groundwater quality standards for radon in this study.