• 한국환경보건학회지
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• 제42권6호
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• pp.419-429
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• 2016

Objectives: According to the new Chemical Control Act from the Korean Ministry of Environment (2014-259), workers handling hazardous chemicals should wear personal protective equipment (PPE). However the act simply states in basic phrases that every worker handling one or more of the 69 listed chemicals should wear PPE and does not consider the unique hazard characteristics of chemicals and work types. The main purpose of this study is to provide basic data to revise the act to suit particular work processes and situations. Methods: The hazard rank of the substances was classified based on hazardous characteristics such as LC50 and vapor pressure using matrix analysis. The workplace exposure risk of the substances was also determined through a matrix analysis based on the previously determined hazard ranks and the demands of manual handling together with the likelihood of accident frequency of the operation combined with the exposure of workers during spill accidents. Results: To meet the demands for developing subsequent guidelines for the risk-based application of PPE in hazardous workplaces, this study sorted the 69 listed chemicals into five hazardous categories based on their LC50 and vapor pressures, and also assigned exposure categories according to exposure vulnerability for various types of work which are frequently performed throughout the life cycle of the chemicals. Conclusion: In the next study, an exposure risk matrix will be produced using the hazard rank of chemicals and workplace exposure risk, and then PPE will be selected to suit the categories of the exposure risk matrix.

• 한국환경보건학회지
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• 제37권5호
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• pp.358-368
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• 2011

Objectives: In order to evaluate the association between occupational exposure to chloroethylene (TCE) and risk of non-Hodgkin lymphoma (NHL), we conducted a meta-analysis of retrospective cohort studies and casecontrol studies and attempted to summarize the evidence of the association from molecular-epidemiological studies and experiments with human cells. Methods: In the meta-analysis, we restricted the analysis to those studies with data for chlorinated solvents, degreasers, or TCE. Studies involving dry cleaners or launderers were excluded from the analysis because use of TCE as a dry cleaning fluid has been rare since the 1960s. The data were combined using a random-effects model to estimate the summary risks (OR and RR) and 95% confidence intervals (CIs). Molecular evidence of the effect of TCE on human immune system were also reviewed and summarized. Results: Occupational exposure to TCE was strongly associated with NHL among cohort studies (number of studies=13, summary RR=1.33, 95% CI=1.04-1.70) whereas the association was not statistically significant among case-control studies (number of studies=15, summary OR=1.10, 0.98-1.23). When exposure level was considered, it became statistically significant for the highest exposure level (number of studies=5, summary OR=1.70, 1.25-2.32). Molecular evidences showed that TCE exposure in human or cultured human cells may cause a significant decrease immune cell subsets and changes in hormone levels related to immune response. Conclusions: Our results from meta-analysis and additional molecular evidence suggest that occupational exposure to TCE may cause NHL. However, unmeasured potential confounding and unclear dose-response relationships warrant further study on the role of TCE exposure in NHL carcinogenesis.

• 한국환경보건학회지
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• 제49권1호
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• pp.22-29
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• 2023

Background: The existing research results on the combined toxicity of these pollutants using mammals, such as rodents, are insufficient, especially in relation to changes in the immune system. Objectives: This study aims at evaluating the cellular immune response to PE-MPs solely or when combined with Pb, which possess excellent adsorption capacity with PE-MPs and is commonly co-exposed in our daily lives. Methods: The study investigated the cellular immune function of 9-week ICR mice with 28 days exposure to PE-MPs (2 mg/mouse/day) and Pb (0.1 mM in distilled water) individually and in combination. PE-MPs were administered via gastric intubation while the lead intake was conducted via the oral drinking water route. Cellular immunity was evaluated by analyzing the production for T_H1 cytokines namely, TNF-α and IFN-𝛾 and T_H2 cytokines, IL-4 and IL-6 in culture supernatants from polyclonally activated splenic mononuclear cells ex vivo. Results: Both the PE-MPs only and the PE-MPs+Pb exposure group revealed an increased T_H1 response with elevated TNF-α and IFN-𝛾 levels and downregulated T_H2 response with low IL-4, and IL-6 production levels compared to the control group. Furthermore, an increased IFN-𝛾/IL-4 ratio was found in the PE-MPs only and PE-MPs+Pb exposure groups, which indicated the skewedness to T_H1 response. Meanwhile, reduced blood hemoglobin levels and increased levels of IL-4, the dominant T_H2 cytokine in the Pb-only exposure group, were observed. Conclusions: Our current findings on the predominance of T_H1 immune response in the PE-MPs and PE-MPs+Pb groups suggest that PE-MPs could be responsible for the predominant induction of the cellular immune changes. This finding could be used as an important landmark in research related to T_H1 predominance, such as autoimmune diseases. It suggests that additional research on immune modulation using longer exposure durations or the same exposure route is required to elucidate stronger findings.

• 환경생물
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• 제21권4호
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• pp.321-327
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• 2003

Differences between the principles for the radiological protection of man and the environment are compared. The derived levels of exposure for man and biota recommended by the international agencies with dose rates for chronic radiation producing effects at different levels of biological organization were given in terms of the biological effects. Cytogenetic effects on plants after an exposure to ionizing radiation at low doses alone and in combination with other factors are discussed. A wide range of experimental data were analysed and the general conclusions were extracted to cover the topics such as non-linearity of dose response, synergistic and antagonistic effects of the combined exposure of different factors, radiation-induced genomic instability, and the phenomena of radioadaptation.

• 한국연초학회지
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• 제20권1호
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• pp.99-107
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• 1998

Numerous studies have demonstrated a negative association between cigarette smoking and Parkinson's disease. The present study was undertaken to investigate whether chronic exposure of mice to cigarette smoke a(footed the metabolism of 1-methyl-1113,6-tetrahydro-pyridine (MPTP) by cytochrome P4SO (P-450) or flavin-containing monooxygenase (FMO) in the hepatic microsomes of C57BL6/J mice. Adult male C57BL6/J mice were exposed to mainstream smoke generated from 15 cigarettes for 10 min a day and 5 day per week for 6 weeks. MPTP (10 mg/kg body weight) was administered to mice by subcutaneous injection for 6 consecutive days. Microsolnal P-450 content was increased by MPTP, smoke exposure, or both, but NADPH cytochrome P-450 reductase activity was rather decreased by the same treatments. The activities of benzo(a)pyrene hydroxylase, 7-ethoxycoumarin O-deethylase and ethoxyresorufin O-deethylase were significantly increased by the exposure of cigarette smoke, but were not or little affected by MPTP treatment. Benzphetamine N-demethylase activity was not affected either by MPTP treatment or by cigarette smoke exposure, but it was significantly increased by the combined MPTP treatment with cigarette smoke exposure, showing their synergic effect for the induction of the enzyme activity. Interestingly, in vitro studies of hepatic FMO and P-450 system both O-oxygenation and N-demethylation of MPTP were increased in the smoke-exposed or in the MPTP-treated mice. These results suggest that the enhancement in the N-demethylation as well as O-deethylation of P-450 system and in the N-oxygenation of FMO activity by cigarette smoke exposure in mouse liver may contribute to attenuating the neurotoxic effects of MPTP on the nigrostriatal dopaminergic neurons.

• 대한방사선방어학회:학술대회논문집
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• 대한방사선방어학회 2009년도 추계 학술발표
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• pp.116-117
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• 2009

• 한국산학기술학회논문지
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• 제19권9호
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• pp.279-287
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• 2018

실란트는 현대 건축물의 중요한 요소로 사용되고 있으며, 습기, 공기, 기타 물질의 침입에 대한 방벽을 제공함으로서 내후성에 대한 건물 보호의 역할을 한다. 다양한 환경에 노출되어 물리적, 화학적, 기계적 특성이 변화되어 수명이 단축되는 경우가 많으며, UV, 습기, 온도 신축 등은 내구성과 직결되는 중요한 이슈이다. 본 연구에서는 구조용 실링마감재의 내구성능을 실내에서 검증하기 위한 장비로서 외기의 환경을 모사할 수 있는 복합열화시험 챔버를 제작하였다. 황사, 산성비, 미생물에 의한 오염 등 특이 기상 상황의 재현은 어려우며 외기 환경을 100 % 모사하는 것은 불가능한 것으로 판단되며, 구조용 실링재의 옥외폭로시험방법과 복합열화시험장치에 대한 내후성 시험 결과 간의 상관관계를 통해 재현성을 확보하고자 연구하였다. 옥외폭로시험의 변위량 시험 결과 실링재의 응집력이 분해되어 연질화가 진행되는 것으로 판단되었고, 옥외폭로 1년 후 변위는 초기 물성치보다 3600 Pa에서 3배 정도 차이가 나는것을 볼 수 있었고, 비교제품의 경우 최대 7배까지 변위가 차이나는 것으로 확인되었다. 복합열화시험장치에서 변위시험결과 열화되어 탄성 및 인장특성이 감소하는 경향을 나타내었다. 변성실리콘 실링재의 경우는 현재 400 Cycle을 완료하여 옥외폭로 12개월의 물성저하를 확인하였다. 시험체의 변형은 육안으로는 확인할 수 없어 상대적으로 실리콘 실링재 제품보다 상태 안정성이 양호한 것으로 판단된다. 옥외폭로시험 결과, 복합열화시험장치가 체계화되어 관련 지침 또는 규격 등에 제안된다면, 실제 사용환경에서 12개월의 예상수명을 실내에서 3개월 미만에서 검증할 수 있는 방법으로 향후, 경제적 손실저감, 공기단축, 설계에 예상 가능한 재료의 선정 등에 활용될 것으로 기대된다.

• Computers and Concrete
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• 제21권6호
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• pp.649-659
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• 2018

Adaptive neuro-fuzzy inference systems (ANFIS) can be efficient in modelling non-linear, complex and ambiguous behavior of cement-based materials undergoing combined damage factors of different forms (physical and chemical). The current work investigates the use of ANFIS to model the behavior (time of failure (TF)) of a wide range of concrete mixtures made with different types of cement (ordinary and portland limestone cement (PLC)) without or with supplementary cementitious materials (SCMs: fly ash and nanosilica) under various exposure regimes with the most widely used chloride-based de-icing salts (individual and combined). The results show that predictions of the ANFIS model were rational and accurate, with marginal errors not exceeding 3%. In addition, sensitivity analyses of physical penetrability (magnitude of intruding chloride) of concrete, amount of aluminate and interground limestone in cement and content of portlandite in the binder showed that the predictive trends of the model had good agreement with experimental results. Thus, this model may be reliably used to project the deterioration of customized concrete mixtures exposed to such aggressive conditions.

• 복식문화연구
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• 제13권3호
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• pp.425-438
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• 2005

This study is to examine the types of expression and aesthetic characteristics of on-line game characters by analyzing those game characters' body and their costume that appear in various domestic on-line game sites. It is shown in this study that types of the human bodies and costume expressed through the game characters are grouped into five categories such as exposure and tightness, enlargement and exaggeration, curtailment and simplification, gender stereotype and unification. Furthermore, there are four typical aesthetic characteristics resulting from those types of expressions; First, 'grotesque' is expressed in the form of extreme enlargement and exaggeration, extreme exposure and concealment, combined images among human, animal or machine, or monstrous devilish images. Second, in an effort to express 'eroticism', bodies are directly exposed, see-through costumes are used in order to emphasize the body lines or very tight designs are used. Third, 'futuristic' characteristics are shown through geometrical shape and silhouette, machine-like details, strong artificial colors or glossy hi-tech material. Lastly, 'pastiche' is expressed with reconciliation of variety of costumes of game characters. Various opposite or heterogeneous styles are combined or harmonized each other to show pastiche, of which examples are male and female, superior culture and inferior one, rich and poor, oriental and western, human and machine, human and nature or past and future, etc.

• 한국철도학회논문집
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• 제8권2호
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• pp.188-194
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• 2005

Aging characteristics of glass fabric/phenolic composites for tilting train subjected to combined environmental aging factors were investigated. A 2.5KW accelerated aging tester with a xenon-arc lamp was used to provide environmental aging factors such as temperature, moisture, and ultraviolet. A series of aging tests were conducted up to 3000 hours and several types of specimens were prepared along the warp direction and the fill direction. Mechanical degradations for tensile, flexural, and shear properties were evaluated as a function of exposure times through a material testing system. Thermal analysis properties such as storage shear modulus, loss shear modulus, and tan 3 were measured through a dynamic mechanical analyzer. Finally exposed surfaces of the composites were examined using a scanning electron microscope. According to the experimental results, mechanical properties and thermal analysis properties of glass fabric/phenolic composites were found to be slightly degraded as a function of exposure times due to combined environmental effects.