• Safety and Health at Work
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• v.2 no.1
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• pp.39-51
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• 2011

Objectives: This study was designed to evaluate exposure levels of various chemicals used in wafer fabrication product lines in the semiconductor industry where work-related leukemia has occurred. Methods: The research focused on 9 representative wafer fabrication bays among a total of 25 bays in a semiconductor product line. We monitored the chemical substances categorized as human carcinogens with respect to leukemia as well as harmful chemicals used in the bays and substances with hematologic and reproductive toxicities to evaluate the overall health effect for semiconductor industry workers. With respect to monitoring, active and passive sampling techniques were introduced. Eight-hour long-term and 15-minute short-term sampling was conducted for the area as well as on personal samples. Results: The results of the measurements for each substance showed that benzene, toluene, xylene, n-butyl acetate, 2-methoxy-ethanol, 2-heptanone, ethylene glycol, sulfuric acid, and phosphoric acid were non-detectable (ND) in all samples. Arsine was either "ND" or it existed only in trace form in the bay air. The maximum exposure concentration of fluorides was approximately 0.17% of the Korea occupational exposure limits, with hydrofluoric acid at about 0.2%, hydrochloric acid 0.06%, nitric acid 0.05%, isopropyl alcohol 0.4%, and phosphine at about 2%. The maximum exposure concentration of propylene glycol monomethyl ether acetate (PGMEA) was 0.0870 ppm, representing only 0.1% or less than the American Industrial Hygiene Association recommended standard (100 ppm). Conclusion: Benzene, a known human carcinogen for leukemia, and arsine, a hematologic toxin, were not detected in wafer fabrication sites in this study. Among reproductive toxic substances, n-butyl acetate was not detected, but fluorides and PGMEA existed in small amounts in the air. This investigation was focused on the air-borne chemical concentrations only in regular working conditions. Unconditional exposures during spills and/or maintenance tasks and by-product chemicals were not included. Supplementary studies might be required.

• Biomedical Science Letters
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• v.9 no.1
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• pp.43-49
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• 2003

This study was carried out to investigate the effect of crude ginseng saponin (CGS) on blood chemical parameters in adult female guinea pigs exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). A total of 80 guinea pigs (800$\pm$20g) were divided into 8 groups: group 1 (normal control group) was given vehicle (corn oil containing small amount of acetone and DMSO) and saline; group 2 (single TCDD-treated) received TCDD (1 $\mu\textrm{g}$/kg, i.p.) and saline (i.p.); groups 3 and 4 were administered CGS at a daily i.p. doses of 10 and 20 mg/kg for 4 weeks, respectively; groups 5 and 6 were administered CGS (10 and 20 mg/kg, respectively) for 5 weeks starting 1 week before TCDD-exposure; groups 7 and 8 were administered CGS (10 and 20 mg/kg, respectively) for 3 weeks from 1 week after TCDD-exposure. CGS was prepared by Diaion HP-20 adsorption chromatography. Body weights of G2 were significantly decreased from the and week after TCDD-exposure (P<0.01). Body weights of the CGS-treated groups were also decreased by TCDD-exposure but the weight loss was greatly retarded compared with that of G2. Increase in blood glucose, amylase, lipase, total cholesterol, triglyceride, AST and LDL-cholesterol levels by TCDD exposure was significantly attenuated by the CCS-treatment (P<0.05). From these results, we found that saponin, the main active ingredient of gineseng, played a protective role in TCDD-induced toxicity and ginseng protected female animals from dioxin-induced toxic manifestation.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.3
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• pp.272-280
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• 2014

Objectives: The purpose of this study was to evaluate the characteristics of worker exposure to hazardous chemical substances and propose the direction of work environment management for protecting worker's health in the semiconductor assembly process. Methods: Four assembly lines at two semiconductor manufacturing companies were selected for this study. We investigated the types of chemicals that were used and generated during the assembly process, and evaluated the workers' exposure levels to hazardous chemicals such as benzene and formaldehyde and the current work environment management in the semiconductor assembly process. Results: Most of the chemicals used at the assembly process are complex mixtures with high molecular weight such as adhesives and epoxy molding compounds(EMCs). These complex mixtures are stable when they are used at room temperature. However workers can be exposed to volatile organic compounds(VOCs) such as benzene and formaldehyde when they are used at high temperature over $100^{\circ}C$. The concentration levels of benzene and formaldehyde in chip molding process were higher than other processes. The reason was that by-products were generated during the mold process due to thermal decomposition of EMC and machine cleaner at the process temperature($180^{\circ}C$). Conclusions: Most of the employees working at semiconductor assembly process are exposed directly or indirectly to various chemicals. Although the concentration levels are very lower than occupational exposure limits, workers can be exposed to carcinogens such as benzene and formaldehyde. Therefore, workers employed in the semiconductor assembly process should be informed of these exposure characteristics.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1090-1098
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• 2005

Benzoyl peroxide is very toxic to aquatic organisms but environmental concentration or exposure effects were not studied. Distribution of the chemical among multimedia environment was estimated using EQC(Equilibrium Criterion) model based on the physical-chemical properties to evaluate the risk of benzoyl peroxide in environment. Level I describes a situation that 100,000 kg of benzoyl peroxide is emitted into the environment which is equilibrium and steady-state without degradation and advection condition. Level II describes a situation that a constant rate of 1,000kg/h of benzoyl peroxide is continuously discharged into the environment which is equilibrium and steady-state with degradation and advection condition. Level III describes a situation that 1,000 kg/h of benzoyl peroxide is continuously introduced in each air, water, soil, and sediment compartment which are non-equilibrium and steady-state with degradation, advection, and inter-media transfer condition. In Level I and II calculations the chemical was distributed to soil(68.3%) and water(28.7%). In Level III calculation it was primarily distributed to soil(99.9%) and overall residence time was estimated to be 3.4 years. Benzoyl peroxide can be persistent in environment.

• Journal of Environmental Health Sciences
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• v.45 no.3
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• pp.231-237
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• 2019

Objective: The objective of this study was to propose a method using population risk to assess the local background exposure effect of harmful pollutants from chemical accidents in Ulsan. Methods: The benzene was selected as representative harmful pollutant. The concentrations of benzene were measured and analyzed at 40 sites in Ulsan city in September, 2018. The data from National Statistics office in Korea were used for population density, and the Integrated Risk Information System (IRIS) data from US EPA were used for unit risk. Results: The risk assessment can be carried out by considering the background population risk. The background population risk was calculated as 5.01 persons per million for exposure to benzene in Ulsan, and therefore may be used as a adjusted background method in case of chemical accident caused by benzene. Conclusions: This study may provide the evidence that background exposure effect and risk to harmful pollutants from chemical accidents would be useful.

• Journal of Applied Reliability
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• v.7 no.4
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• pp.173-181
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• 2007

Out door exposure to daylight and weather climate conditions can cause adverse effect on the properties of automotive plastic materials. The effects of sunlight exposure, especially ultra violet (UV) radiation, can break down the chemical bonds in a polymeric material. This degradation process is called photo-degradation and ultimately leads to color changes, cracking, chalking, the loss of physical properties and deterioration of other properties. To explore the effect of sunlight exposure on the automotive materials, this study investigated photo-oxidation degree and surface property change of molding parts by analytical methods. For the further study, accelerated weathering test methods are proposed, which can correlate with out door weathering, to predict long term performance of automotive plastic materials.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.392-395
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• 2008

In an attempt to delineate the direct effect of arsenite-induced endothelial dysfunction on nitric oxide (NO) production, confluent bovine aortic endothelial cells (BAEC) were incubated with arsenite, and endothelial NO synthase expression and NO production were measured. Exposure of arsenite decreased NO production for up to 24h. This decrease was accompanied by decreases in cAMP, protein kinase A (PKA) activity, and furthermore, significant reduction of pCREB. In conclusion, this study is the first to demonstrate that exposure of arsenite decreases NO production by a reduction of pCREB and PKA activity that may be mediated by cAMP, leading to endothelial dysfunction.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2005.11a
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• pp.295-300
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• 2005

This Study intends to find out the subjective symptom of Construction Business Worker caused by chemical material exposure, also willing to research how much they are exposed to VOCs(Volatile Organic Compounds) and under how much harmful circumstance they are working. As the results, the job group among construction business workers which is most highly dangerous degree to be taken ill of Multiple Chemical Sensitivity is Interior Worker, next following by order of Clerical Worker, Exterior Worker. According to this result, the continuous exposure in high density must be prevented by the measures for Interior Worker also to be bestowed a compulsory break during working hour for regular exposure to the open air,

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.583-585
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• 2004

In this paper, we synthesized a new photo-crosslinkable polyitaconimide containing cinnamoyl moiety by radical polymerization. Also, the NLC alignment capabilities on these photopolymer surfaces were studied. Good LC alignment with W exposure on the polyitaconimide surfaces can be obtained. A homogenous alignment using UV exposure on the polyitaconimide with 1-carbon chain cinnamoyl group and 4-carbon chain cinnamoly group can be obtained. However, the homeotripic alignment using UV exposure was observed on polyitaconimide with 6-carbon chain cinnamoyl. The LC aligning ability on the polyitaconimide depends on the side chain length of photopolymer.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.358-362
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• 1987

The interaction of oxygen with polycrystalline nickel surface has been studied by investigating the X-ray photoelectron spectra of O 1s, Ni $2p_{3/2}$, and their valence band electrons. By comparing the oxygen exposure of this work with the reported results of LEED, AES, and work function measurements, it is found that the atomic oxygen, adsorbed dissociatively in the initial stage of exposure, is responsible for a p(2 ${\times}$ 2) structure and a subsequent c(2 ${\times}$ 2) structure on the Ni(100) surface. This dissociatively adsorbed oxygen species forms surface NiO layer subsequently on further oxygen exposure. The NiO layer is more easily formed with the increasing temperature. Non-stoichiometric oxygen species is also found to accompany the NiO layer. It appears prior to the formation of bulk NiO at all of the temperatures of this work except at 523K.