• Safety and Health at Work
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• 제8권3호
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• pp.258-266
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• 2017

Background: Welders are exposed to many known and suspected carcinogens. An excess lung cancer risk among welders is well established, but whether this is attributable to welding fumes is unclear. Excess risks of other cancers have been suggested, but not established. We investigated welding cancer risks in the population-based Canadian Census Health and Environmental Cohort. Methods: Among 1.1 million male workers, 12,845 welders were identified using Standard Occupational Classification codes and followed through retrospective linkage of 1991 Canadian Long Form Census and Canadian Cancer Registry (1992-2010) records. Hazard ratios (HRs) were calculated using Cox proportional hazards models based on estimated risks of lung cancer, mesothelioma, and nasal, brain, stomach, kidney, and bladder cancers, and ocular melanoma. Lung cancer histological subtypes and risks by industry group and for occasional welders were examined. Some analyses restricted comparisons to blue-collar workers to minimize effects of potential confounders. Results: Among welders, elevated risks were observed for lung cancer [HR: 1.16, 95% confidence interval (CI): 1.03-1.31], mesothelioma (HR: 1.78, 95% CI: 1.01-3.18), bladder cancer (HR: 1.40, 95% CI: 1.15-1.70), and kidney cancer (HR: 1.30, 95% CI: 1.01-1.67). When restricted to blue-collar workers, lung cancer and mesothelioma risks were attenuated, while bladder and kidney cancer risks increased. Conclusion: Excess risks of lung cancer and mesothelioma may be partly attributable to factors including smoking and asbestos. Welding-specific exposures may increase bladder and kidney cancer risks, and particular sources of exposure should be investigated. Studies that are able to disentangle welding effects from smoking and asbestos exposure are needed.

• Korean Chemical Engineering Research
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• 제47권2호
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• pp.248-257
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• 2009

본 연구에서는 배출량산정모델과 다중매질모델을 활용하여 환경오염물질의 노출도를 예측하였으며 위해도를 평가하였다. 연구대상 화학물질로써 8종(아세트알데히드(acetaldehyde), 아크릴로니트릴(acrylonitrile), 아닐린(aniline), 벤젠(benzene), 사염화탄소(carbon tetrachloride), 디클로로메탄(dichloromethane), 포름알데히드(formaldehyde), 염화비닐(vinyl chloride))의 물질을 선택하였으며, 대상지역은 공단지역을 포함하는 도심 지역을 선택하였다. 배출량은 지리지형정보를 활용하여 점배출원과 비점배출원을 동시에 고려하여 산정하였으며, 다중매질모델은 지역적 특성을 반영할 수 있는 모델을 선택하였다. 유해성 자료는 미국 환경청의 IRIS(Integrated Risk Information System) 유해성 데이터베이스를 활용하였다. 모델링 자료와 유해성 자료를 이용하여 위해성을 평가한 결과, 물질별로 위해도가 높은 지역을 발견할 수 있었으며 우선적으로 관리해야 할 물질을 선별할 수 있었다.

• Biomolecules & Therapeutics
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• 제14권3호
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• pp.152-159
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• 2006

Electro-magnetic fields and static magnetic fields generated from diverse home/environmental sources have been reported that these could make harmful effects on the human health such as suppression of immunity and tumorigenesis. However, the mechanisms for the biologic effects of electro-magnetic fields or static magnetic fields are still remained unclear. In this study, we examined the in vitro effects of static magnetic fields (SMF) on murine peritoneal macrophages. The cells were exposed in vitro to SMF of $150{\sim}250$ or $350{\sim}450$ G in 5% $CO_2$-incubator. The phagocytic activity of murine peritoneal macrophages was inhibited under exposure to SMF. In order to provide a more complete picture of molecular mechanism for the biological effect of SMF, we compared the levels of total proteins from macrophages with or without exposure to SMF using quantitative proteomic analysis. Proteins which were differentially expressed in macrophages exposed to SMF compared with non-exposed macrophages, were identified. Among them, the levels of trypsinogen 16, lactose-binding lectin Mac-2, galactoside-binding lectin, actin-like (Put. ${\beta}-actin$, vimentin) and electron transferring flavoprotein beta polypeptide were enhanced under exposure to SMF. These results suggest that SMF can affect the phagocytic activity of macrophages via diverse mechanisms.

• Tribology and Lubricants
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• 제36권5호
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• pp.267-273
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• 2020

This study experimentally investigates hydrophobic surfaces fabricated via additive manufacturing. Additive manufacturing, commonly known as 3D printing, is the process of joining materials to fabricate parts from 3D model data, usually in a layer-upon-layer manner. Digital light processing is used to fabricate hydrophobic surfaces in this study. This method uses photo-curable resins and ultraviolet (UV) sources. Moreover, this technique generally has faster shaping speeds and is advantageous for the fabrication of small components because it enables the fabrication of one layer at a time. Two photo-curable resins with different compositions are used to fabricate micro-patterns of hydrophobic surfaces. The resins are composed of a photo-initiator, monomer, and oligomer. Experiments are conducted to determine suitable process conditions for the fabrication of hydrophobic surfaces depending on the type of resin. The most important factors affecting the process conditions are the UV exposure time and slice thickness. The fabrication capability according to the process conditions is evaluated using the side and top views of the micro-patterns observed using a microscope. The micro-patterns are collapsed and intertwined when the exposure time is short because sufficient light (heat) is not applied to cure the photo-curable resin with a given slice thickness. On the other hand, the micro-patterns are attached to each other when the exposure time is prolonged because the over-curing time can cure the periphery of a given shape. When the slice is thicker, the additional curing area is enlarged in each slice owing to the straightness of UV light, and the slice surface becomes rough.

• 생물환경조절학회지
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• 제29권2호
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• pp.181-188
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• 2020

본 연구는 국내 특산식물이며 관상소재로 개발이 가능한 산꼬리풀의 효과적인 육묘조건을 구명하기 위해 수행되었다. 육묘는 토양 종류와 비료 농도, 차광정도, 추비 농도, 종자의 광원 전처리 및 채종 시기별로 각 요인을 달리하여 수행하였다. 연구 결과, 산꼬리풀은 원예상토에서 생육이 우수하였으며, 혼용토에서는 비료 첨가 시 생육이 억제되었다. 차광은 55% 차광조건에서 무차광에 비해 전체적인 생육이 향상되었다. 고농도(1000mg·L^-1)의 Hyponex는 육묘 시 생육을 촉진하였으며, 파종 전 종자에 대한 적색광 조사는 추후 초장과 생체중 향상에 효과적이었다. 채종 시기는 2018년도 종자가 2017년 종자보다 생육이 우수하였다.

• 한국대기환경학회지
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• 제31권5호
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• pp.411-429
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• 2015

The Korea Ministry of Environment has established an air quality standard for $PM_{2.5}$ in 2012 and it is effective from January 2015. In this study, we review various aspects of $PM_{2.5}$ in China, including its measurement, modeling, source apportionment, and health effect, and suggest future research directions for $PM_{2.5}$ studies in Korea. Measurements studies for $PM_{2.5}$ have examined organic marker compounds and $^{14}C$ as well as inorganic aerosols for distinguishing sources. Modeling results supported that the control of $PM_{2.5}$ pollution in big city needs effective cooperation between city and its surrounding regions. The major $PM_{2.5}$ sources in China have been identified to be secondary sulfur, motor vehicle emissions, coal combustion, dust, biomass burning, and industrial sources, however, they have seasonal dependency. Especially, the severe haze pollution event during January 2013 over eastern and northern China was driven to a large extent by secondary aerosol formation. Short-term exposure to $PM_{2.5}$ is strongly associated with the increased risk of morbidity and mortality from cardiovascular and respiratory diseases, as well as total non-accidental mortality. Considered previous $PM_{2.5}$ studies in China, analysis of specific organic species using online measurement, chamber experiment for secondary aerosol formation mechanism, and development of parameterizing this process in the model are needed to elucidate factors governing the abundance and composition of $PM_{2.5}$ in Korea.

• 한국도로학회논문집
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• 제20권3호
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• pp.59-64
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• 2018

PURPOSES : We propose a parameter-setting-free harmony-search (PSF-HS) algorithm to determine the individual sound power levels of noise sources in the cases of industrial or road noise environment. METHODS :In terms of using methods, we use PSF-HS algorithm because the optimization parameters cannot be fixed through finding the global minimum. RESULTS:We found that the main advantage of the PSF-HS heuristic algorithm is its ability to find the best global solution of individual sound power levels through a nonlinear complex function, even though the parameters of the original harmony-search (HS) algorithm are not fixed. In an industrial and road environment, high noise exposure is harmful, and can cause nonauditory effects that endanger worker and passenger safety. This study proposes the PSF-HS algorithm for determining the PWL of an individual machine (or vehicle), which is a useful technique for industrial (or road) engineers to identify the dominant noise source in the workplace (or road field testing case). CONCLUSIONS : This study focuses on providing an efficient method to determine sound power levels (PWLs) and the dominant noise source while multiple machines (or vehicles) are operating, for comparison with the results of previous research. This paper can extend the state-of-the-art in a heuristic search algorithm to determine the individual PWLs of machines as well as loud machines (or vehicles), based on the parameter-setting-free harmony-search (PSF-HS) algorithm. This algorithm can be applied into determining the dominant noise sources of several vehicles in the cases of road cross sections and congested housing complex.

• 한국식생활문화학회지
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• 제16권1호
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• pp.1-12
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• 2001

The main purposes of this study are to know the contents and forms of impressions that the general public, and the consumerists and environmentalists have of irradiated food, and to know what information of irradiated food influences their impressions. Other purposes are to know what sources those impressions derive from, to know which media they have recently been exposed to and paid attention to irradiated food through, to know which sources they trust of information regarding irradiated food most greatly, and finally to suggest policies and strategies of communication in order to shed positive impressions of irradiated food on people. This study was conducted through the person-to-person interview survey toward 1,200 adults, and 150 consumerists and environmentalists in 1999. Adults are sampled nationally in South Korea. Only 8.7% of the general public have heard of irradiated food. Impressions of irradiated food that the general public mentioned most frequently are: harmful, insecure, negative, etc. The consumerists and environmentalists were found to have the most inaccurate knowledge of irradiated food. Television and newspaper were the major sources of impressions of, exposure to and focus of attention on irradiated food. Based on these results, we seem to devise methods to enhance impression of irradiated food by disseminating information of advantages and benefits that irradiation provides food with and to promote the fact that irradiation on food is totally irrelevant to being radioactive, danger of a nuclear power plant, genetically modifying food, etc.

• 한국환경보건학회지
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• 제39권1호
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• pp.32-42
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• 2013

Objectives: Cryptosporidium, a protozoan parasite, has been recognized as a frequent cause of waterborne disease due to its extremely strong resistance against chlorine disinfection. Although there has as yet been no report of a Cryptosporidium outbreak through drinking water in Korea, it is important to estimate the health risk of Cryptosporidium in water supply systems because of the various infection cases in human and domestic animals and frequent detection reports on their oocysts in water environments. Methods: This study evaluated the annual infection risk of Cryptosporidium in tap water using the quantitative microbial risk assessment technique. Exposure assessment was performed upon the results of a national survey on Cryptosporidium on the water sources of 97 large-scale water purification plants in Korea, water treatment efficacy, and daily unboiled tap water consumption. The estimates of the US Environmental Protection Agency on the mean likelihood of infection from ingesting one oocyst were applied for effect assessment. Results: Using probabilistic methods, mean annual infection risk of Cryptosporidiosis by the intake of tap water was estimated to fall within the range of $2.3{\times}10^{-4}$ to $1.0{\times}10^{-3}$ (median $5.7{\times}10^{-4}$). The risk in using river sources was predicted to be four times higher than with lake sources. With 0.5-log higher removal efficacy, the risk was estimated to be $1.8{\times}10^{-4}$, and could then be lowered by one-third. Conclusions: These estimations can be compared with acceptable risk and then used to determine the adequacy and priority of various drinking water quality strategies such as the establishment of new treatment technology.

• Journal of Microbiology
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• 제41권1호
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• pp.34-40
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• 2003

Aspergillus nidulans, a homothalic ascomycete, has a complete sexual reproductive cycle as well as an asexual one. Both sexual and asexual development are known to be genetically programmed, but are also strongly affected by environmental factors including nutrients, light, temperature and osmolarity. We have examined these factors to define favored conditions for fruiting body (cleistothecium) formation. In general, fruiting body formation was enhanced where carbon and nitrogen sources were sufficient. Limitation of C-source caused predominant asexual development while inhibiting sexual development. When higher concentrations of glucose were supplied, more cleistothecia were formed. Other carbon sources including lactose, galactose and glycerol made the fungus develop cleistothecia very well, whereas acetate caused asexual sporulation only. Organic nitrogen sources like casein hydrolysate and glycine, and an increase in nitrate or ammonium concentration also enhanced sexual development. In addition to nutrient effects, low levels of aerobic respiration, caused either by platesealing or treatment with various chemicals, favored sexual development. Carbon limitation, light exposure and a high concentration of salts promoted asexual development preferentially, suggesting that stress conditions may drive the cell to develop asexual sporulation while comfortable and wellnourished growth conditions favored sexual development.