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아파트 실내 환경에서 실시간 측정시스템을 활용한 HONO 농도 측정 및 생성기작 연구
박승식(Seung Shik Park),홍진의(Jin H. Hong),이재훈(Jai H. Lee),김영준(Young J. Kim),조성용(Sung Y. Cho),김승재(Seung J. Kim) 한국대기환경학회 2008 한국대기환경학회지 Vol.24 No.1
Nitrous acid (HONO) can be produced by heterogenous reactions of nitrogen dioxide on surface materials and direct emission from combustion sources. However, a little is known of indoor HONO levels or the relationship between residential HONO, NO, and NO₂ concentrations in occupied houses. Therefore, we measured simultaneously NO, NO2, and HONO concentrations in living room of an apartment using continuous analyzers to study the production of HONO (June 22~30, 2006). The 4-min average concentrations of indoor NO, NO₂, and HONO were 4.3 (range: 0.4~214.3), 10.3 (2.0~87.3), and 1.8 ppb (0.3~7.7), respectively. Peak levels of HONO up to 7.7 ppb and 24-hr averages as high as 1.7 ppb were measured. In agreement with previous studies, indoor HONO concentrations increased during operation of an unvented gas range. Examination of the observed kinetics suggests that the secondary production of indoor HONO, possibly as a result of heterogeneous reactions involving NO₂ and H₂O is associated with [NO₂]²[H₂O] (r²=0.88) rather than with [NO][NO₂][H₂O] (r²=0.75). Three combustion experiments at nighttime were also carried out to investigate the effects of vented combustion on the HONO, NO, and NO₂ concentrations. It was found to release HONO for 10~15 minutes after NO and NO₂ source was turned off, and peak values were finally attained. Compared to unvented combustion, peak NO₂ and HONO concentrations were 3.2 and 2.0 times lower at weak vented combustion (air flow: 340㎥/hr) and 4.9 and 2.4 times lower at strong vented combustion (air flow: 540 ㎥/hr), respectively, emphasizing importance of operating ventilation hood fan during combustion to improve indoor air quality.
분산강화형 초내열합금의 threshold 응력 예측을 위한 모델링
권숙인,최성배,변재원,이재훈 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.6
The creep behavior of PM1000 alloy, ODS Ni-base superalloy with 0.6wt%Y₂O₃ was investigated in order to understand the role of dispersoids during high temperature creep deformation as a modeling alloy. Nimonic75 alloy which has no dispersoids but has almost the same chemical composition as PM1000 was selected as a reference alloy. Creep tests were performed at 800℃ 900℃ and 1000℃. In contrast to Nimonic75, the PM1000 alloy showed the threshold behavior at certain stress level under which no detectable creep strain proceeds, TEM observations indicated that there was an attractive interaction between particles and dislocations. A new model to predict the threshold stress in high temperature creep was proposed in this study. The predicted threshold stresses by this model agreed well with the experimental results.