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AE(Acoustic Emission) 기법을 통한 재료 피로파괴 감지 장치 개발
최정황(Junghwang Choi),김대용(Daeyong Kim),손민영(Minyoung Son),김찬묵(Chanmook Kim),이성욱(Seangwock Lee),강호인(Hoin Kang),나완용(Wanyong Rha) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The purpose of this work is to obtain fundamental data about material fatigue crack detection system using AE method. The acoustic emission as a nondestructive evaluation is one of the tests for realtime monitoring in the advanced countries such as US, Japan, Russia, etc. Characteristic evaluation of AE signal, AE frequency and RMS analysis for state monitoring is also presented in the paper. This test provided the fundamentals of AE method such as crack frequency when applying vibration on the welded pipe.
SCR 촉매와 AOC 촉매에서 환원제 분사에 따른 NO<SUB>x</SUB> 저감효율과 NH₃ 변환효율에 관한 실험적 연구
동윤희(Yoonhee Dong),김지훈(Jihun Kim),최정황(Junghwang Choi),조용석(Yongseok Cho),이성욱(Seangwock Lee),나완용(Wanyong Ra),박현대(Hyundae Park) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
As the environmental regulation of vehicle emission is strengthened, investigations for NOx and PM reduction strategies are popularly conducted. Two current available technologies for continuous NOx reduction onboard diesel vehicles are Selective Catalytic Reduction (SCR) using aqueous urea and lean NOx trap (LNT) catalysts. The experiments were conducted to investigate the NOx reduction performance of SCR system which can control the ratio of NO/NO₂, temperature and SV(space velocity), and the model gas was used which is similar to a diesel exhaust gas. The maximum reduction efficiency is indicated when the NO:NO₂ ratio is 1:1 and the SV is 30,000 h?¹ in 300℃. Generally, ammonia slip from SCR reactors are rooted to incomplete conversion of NH₃ over the SCR. In this research, slip was occurred in 6cases (except low SV and NO:NO₂ ratio is 1:1) after SCR. Among 6 case of slip occurrence, the maximum conversion efficiency is observed when SV is 60,000 h?¹ in 400℃.