• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.366-369
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• 2001

In this study, the matrix Organic Electroluminescence (OEL) device, that was consisted of R,G,B pixels. We fabricated OEL devices by side by side methode and, used organic material Alq3 as green, DCM as red and Butyl PBD as blue ETL. We investigated the characteristic of brightness and current density for matrix OEL device. As the results, each color devices has minimum about $100cd/m^{2}$ brightness and maximum luminescence was $2500cd/m^2$ in green OEL device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.366-369
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• 2001

In this study, the matrix Organic Electroluminescence (OEL) device, that was consisted of R,G,B pixels. We fabricated OEL devices by side by side methode and, used organic material Alq3 as green, DCM as red and Butyl PBD as blue ETL. We investigated the characteristic of brightness and current density for matrix OEL device. As the results, each color devices has minimum about 100 cd/㎡ brightness and maximum luminescence was 2500cd/㎡ in green OEL device

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1343-1350
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• 2007

This paper describes the tests on the reactive power output limit and the Over-Excitation Limiter (OEL) dynamics of a generation unit. The suggested test methods on reactive limit can identify the allowable maximum/minimum reactive power at 100% rated MW in the steady-state unit operation condition. The on-line OEL test method can identify the time characteristics of OEL with the generation output at 50% of the rated MW. These methods are validated by applying to four Yang-Yang pumped storage units with 282 rated MVA each.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.1
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• pp.13-20
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• 2019

Objective: This study was performed to propose a domestic occupational exposure limit(OEL) following a health hazard assessment, calculation of a non-carcinogenicity reference concentration worker($RfC_{worker}$) value, and examination of international agencies' exposure limits. It also recommends legal management within the Occupational Safety and Health Act for PHMG-Phosphate(CAS No. 89697-78-9), It is a humidifier disinfectant that generated many lung injuries. Methods: We have investigated the recommendation or guidelines of foreign OEL for PHMG-Phosphate and the actual state of legal management in Korea. To examine the procedures and methods for recommendation OEL. Toxicological hazard and health hazard classifications were examined and a non-carcinogenicity $RfC_{worker}$ value was calculated for PHMG-Phosphate. An OEL and the necessity of legal management were recommended as well. Results and Conclusions: The OEL for PHMG-Phosphate is recommended to be $0.01mg/m^3$. The recommended OEL is close to 10 times the RfCworker value of $0.000833mg/m^3$ calculated from the chemical dose-response hazard assessment, which is a 2017 study. The CMIT/MIT(3:1) mixture, which was a social issue as a humidifier disinfectant substance, was also exposed to the same ratio in March 2018, establish the OEL. It is recommended to establish OEL for PHMG-Phosphate to prevent worker health hazards and for chemical safety management.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.384-386
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• 2006

This paper deals with tests on the reactive power output limit and the Over-Excitation Limiter (OEL) dynamics of generation unit. The suggested reactive limit test methods can identify the allowable maximum/minimum reactive power at 100% rated MW in the steady-state operation condition. The on-line OEL limit test method can identify the time characteristics of OEL with the generation output at 50% of the rated MW. These methods are validated by applying to Yang-Yang Pumped storage units of 282 MVA.

• Safety and Health at Work
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• v.3 no.1
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• pp.1-10
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• 2012

The aim of this review was to assess current knowledge related to the occupational exposure limit (OEL) for fluid aerosols including either mineral or chemical oil that are generated in metalworking operations, and to discuss whether their OEL can be appropriately used to prevent several health risks that may vary among metalworking fluid (MWF) types. The OEL (time-weighted average; 5 mg/$m^3$, short-term exposure limit ; 15 mg/$m^3$) has been applied to MWF aerosols without consideration of different fluid aerosol-size fractions. The OEL, is also based on the assumption that there are no significant differences in risk among fluid types, which may be contentious. Particularly, the health risks from exposure to water-soluble fluids may not have been sufficiently considered. Although adoption of The National Institute for Occupational Safety and Health's recommended exposure limit for MWF aerosol (0.5 mg/$m^3$ ) would be an effective step towards minimizing and evaluating the upper respiratory irritation that may be caused by neat or diluted MWF, this would fail to address the hazards (e.g., asthma and hypersensitivity pneumonitis) caused by microbial contaminants generated only by the use of water-soluble fluids. The absence of an OEL for the water-soluble fluids used in approximately 80-90 % of all applicants may result in limitations of the protection from health risks caused by exposure to those fluids.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.4
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• pp.350-358
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• 2022

Objectives: For chemical risk assessment in workplaces, it is necessary to determine a reference value through hazard assessment. In general, OEL (Occupational Exposure Limit) is used for this value. However, since chemicals with OEL were not enough, the concept of DNEL (Derived No Effect Level) was introduced in chemical safety assessment. In this study, the possibility and approach of applying DNEL for chemical risk assessment in domestic workplaces were investigated. Methods: The characteristics of OEL and DNEL were investigated. In addition, ACGIH TLV and GESTIS DNEL were compared and the corresponding scopes were analyzed among the chemical substances notified in South Korea. Results: OEL and DNEL are similar concepts reflecting reference values that should not be exposed based on health effects. While their evaluation and derivation are determined based on similar information and procedures, they may vary depending on the responsible actor, data availability, principles of judgment, and more. As a result of the comparative analysis of ACGIH TLV and GESTIS DNEL, it was confirmed that there is some correlation between TWA and DNEL. The conservatism of DNEL was around 50%. Additionally, it was found that the available range of DNEL among chemicals in South Korea is considerable. Conclusions: This study showed that DNEL can be applied when assessing the risk of chemical substances in domestic workplaces considering several regards. However, since this is not the same level as OEL, we have proposed a proper approach to carry out risk assessment step by step.

• Journal of Environmental Science International
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• v.25 no.4
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• pp.505-516
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• 2016

With the development of nanotechnology, nanomaterials are used in various fields. Therefore, the interest regarding the safety of nanomaterial use is increasing and much effort is diverted toward establishment of exposure assessment and management methods. Occupational exposure limits (OELs) are effectively used to protect the health of workers in various industrial workplaces. This study aimed to propose an OEL for domestic multi-walled carbon nanotubes (MWCNTs) based on animal inhalation toxicity test. Basic procedure for development of OELs was examined. For OEL estimation, epidemiological study and quantitative risk assessment are generally performed based on toxicity data. In addition, inhalation toxicity data-based no observed adverse effect level (NOAEL) and benchmark dose (BMD) are estimated to obtain the OEL. Three different estimation processes (NEDO in Japan, NIOSH in USA, and Baytubes in Germany) of OELs for carbon nanotubes (CNTs) were intensively reviewed. From the rat inhalation toxicity test for MWCNTs manufactured in Korea, a NOAEL of $0.98mg/m^3$ was derived. Using the simple equation for estimation of OEL suggested by NEDO, the OEL of $142{\mu}g/m^3$ was estimated for the MWCNT manufacturing workplace. Here, we used test rat and Korean human data and adopted 36 as an uncertainty factor. The OEL for MWCNT estimated in this work is higher than those ($2-80{\mu}g/m^3$) suggested by previous investigators. It may be greatly caused by different physicochemical properties of MWCNT and their dispersion method and test rat data. For setting of regulatory OELs in CNT workplaces, further epidemiological studies in addition to animal studies are needed. More advanced technical methods such as CNT dispersion in air and liquid should be also developed.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.3
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• pp.270-279
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• 2020

Objective: The aim of this study was to propose revision of the occupational exposure limit(OEL) for 1-Bromopropane(1-BP) following a review of the appropriateness of the standard in light of increasing epidemiological data and handling risk. Materials and Methods: The results of toxicity and epidemiologic investigations for 1-BP and agencies' OELs were compared and reviewed through a literature review. In order to investigate the status of 1-BP handling in South Korea, data from work environment actual condition survey results and work environment measurement results were used. Results: The toxicity of 1-BP, such as central nervous system(CNS) damage, peripheral neuropathy, hematological adverse effects, and developmental and reproductive toxicity(male and female) has been reported. ACGIH recommends 0.1 ppm as a TLV-TWA value, but the OEL of South Korea stands at 25 ppm, which is 250 times higher than the TLV-TWA. Although 1-BP is a specially managed substance under the Industrial Safety and Health Law, the currently applied OEL cannot be said to be a safe level based on the results of epidemiological studies to date. In a work environment measurement in 2017, the total number of samples was 626, which were derived from 78 industries, and the average concentration was 1.173 ppm(standard deviation 2.88). Conclusions: To protect the health of workers handling 1-BP, estimated to be 780 in South Korea, it is necessary to strengthen the OEL(TWA) to a level of 0.3 ppm(lower than the 0.34 ppm with known toxic effects), which is believed to be safe as a result of epidemiological investigation. "Skin" notation should be recommended.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.166-169
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• 2000

The Organic Electroluminescence (OEL) device, that was consisted of ALq3(8-hydroxyquinoline aluminum) and TPD(N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine), has been used. We investigated characteristics of brightness and current density about OEL that was oxidated each layers. We used two samples that were fabricated each continuous and non-continuous method. Emission was observed above 10mA/$\textrm{cm}^2$ and luminance was measured to be 1530cd/$\textrm{cm}^2$ at a current density of 100mA/$\textrm{cm}^2$. A luminance of over 2600cd/$\textrm{cm}^2$ was also observed after the final fabrication process.