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NIOSH 와 OSHA 측정 방법을 이용한 이소시아네이트류 발생 공정별 농도 분포 평가
김현욱,강형경 한국산업위생학회 1999 한국산업보건학회지 Vol.9 No.2
The purpose of this study was to compare performances of two analytical methods, the OSHA 42 and two NIOSH 5522, of quantifying total isocyanates in ar. These methods were compared in terms of accuracy and precision and the detection limits using four(4) spiked samples in each of four(4) concentration levels which ranged from 0.25 to 2.0 times of the ACGIH TLV-TWA. In addition, two methods were used to assess airborne concentrations of total isocyanates at the following processes including autobody spray painting, furniture spray painting, polyurethane foaming, urethane adhesion, UV coating, and pigment mixing. The results of this study showed that the NIOSH 5522 method was better than the OSHA 42 method in terms of accuracy, precision, and detection limit for quantifying airborne total isocyanates. It was also clear that the NIOSH method was capable of detecting not only monomeric but also non-monomeric isocyanates. The results of air concentrations of total isocyanates among processes studied indicate that some processes may exceed the recommended level of isocyanates. In addition, to evaluate toxicological effects of total isocyanates, it is recommended to consider additive effects of isocyanates present in mixtures.
내부쉴드 구조에 따른 컴팩트한 폴리머 부싱 설계에 관한 연구
조한구,유대훈,강형경,Cho, Han-Goo,Yoo, Dae-Hoon,Kang, Hyung-Kyung 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.5
This paper describes a study on the design of compact polymer bushing with inner control shield. In the bushing, a high electric stress occurred between field shaper and central conductor by the closely space. Also coaxial cylindrical shield has a great height along the axis to control an electric field. Consequently, all the potentials are raised axially along the field shaper and electric stress is concentrated on a part of the surface of the FRP tube near the upper end of the field shaper. In accordance, the field control can be achieved by means of the designs of such inner control shields. The floating and ring shield designs was decreased electric field concentration at critical parts of the bushing. The shield gaps is formed between field shaper and ring shield. Accordance equipotential lines extend through gaps. As a result, the resulting electrical stress are thus reduced in the range $17{\sim}23%$ in the bushing with floating and ring shield designs. Maxwell 2D simulator based on the boundary element method was also introduced in order to verify the reliability of the polymer bushing. The optimized design uses internal elements for electric stress grading at critical parts of the bushing.