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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℃.
디젤 엔진용 Metal DPF의 재생평형온도(BPT) 특성에 관한 연구
김충희(Chunghui Kim),김현철(Hyunchul Kim),이기수(Geesoo Lee),최정황(Jeonghwang Choi),전문수(Munsoo Chon) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
In this study, a sample of the metal diesel particulate filter (MDPF) was fabricated, which was mounted on a 2.9 L mid-sized diesel engine to evaluate and analyze BPT and thus consider its application to actual diesel engine vehicles. The exhaust gas temperature on the front end of MDPF was changed at one hour interval from 20 ℃ to 30 ℃, and the resulting differential pressure and back pressure characteristics of the filter were analyzed. The international sample and D and K type samples were used for the evaluation, which were classified according to the filter structure. The BPT of the filter were 362 ℃ for the international sample, 350 ℃ for the D type sample, and 336 ℃ for the K type sample. Considering the actual vehicle temperature frequency for each section in prior studies, the results satisfied the regeneration condition in all sections other than the crowded downtown sections.