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질산태 질소 정량을 위한 환원 증류법에서 Devarda’s Alloy의 입자크기 및 함량이 미치는 영향
정석호(Seok Ho Jung),권현재(Hyun Jae Kwon),정덕영(Doug Young Chung),한광현(Gwang Hyun Han) 韓國土壤肥料學會 2011 한국토양비료학회지 Vol.44 No.3
We analyzed the particle size distributions of three commercially available Devarda’s alloy (DA) products, tested the nitrate recoveries of each particle size category, and examined the amounts of DA required for 100% recovery by varying NO3−N concentration from 0.5 to 10 mg. We observed that use of DA coarser than 200 mesh resulted in poor analytical recovery (< 80%). While the tested alloys were considered to be fine enough (>90% of the particles were less than 100 mesh), the recovery dramatically declined from 80% to 10% in a high concentration range (4 to 10 mg N). Satisfactory recovery was obtained by increasing the amount of finer DA (less than 300 or 450 mesh). However, there was no quantitative relationship between the amount of fine DA and nitrate recovered. Generally, the amount of nitrate reduced per unit DA decreased as the recovery efficiency declined. These results suggest that a sufficient amount of DA must be determined based on particle size distribution, and that treatment of at least two levels of DA and comparison of the subsequent change in nitrate recovery is required for soils containing high levels of nitrate. In addition, further studies are encouraged to account for the observed stoichiometric dis-equivalence of recovered nitrate N per unit mass of DA.
호기순환 호흡계를 이용한 토양처리 석탄바닥재의 유기물 분해에 미치는 영향
정석호(Seok-Ho Jung),정덕영(Doug-Young Chung),한광현(Gwang-Hyun Han) 한국토양비료학회 2012 한국토양비료학회지 Vol.45 No.2
석탄 연소 부산물인 비산회 (fly ash)는 이산화탄소 발생을 저감하고 토양 탄소를 격리하는 효과가 있음이 보고된바 있다. 같은 연소 부산물인 석탄바닥재 (bottom ash)는 비 산회와 유사한 화학적 성질을 가지고 있고, 아울러 다공성으로 토양미생물들이 정착하는 적절한 담체로서의 기능을 가지고 있다. 이에 본 연구는 성질이 다른 유기물들 (헤어리베치, 청보리, 유박비료)이 처리된 토양에서 석탄바닥재가 토양 미생물들에 의한 유기물 분해 및 호흡량에 미치는 영향을 조사하였다. 미생물에 의한 유기물의 분해속도는 유박비료, 헤어리베치, 청보리의 순으로 높게 나타났고, 유기물과 석탄바닥재를 함께 처리하였을 때, 유의하게 감소하였다. 이산화탄소 발생량의 경시적인 변화는 유기물의 이분해성에 의존하였으나, 석탄바닥재를 처리하였을 때 유의하게 발생량이 감소하였다. 총 누적 이산화탄소 발생량 또한 이와 유사한 결과를 보였다. 석탄바닥재가 함유하고 있는 중금속 등과 같은 유해물질의 농도가 높지 않다면, 본 연구의 결과들은 석탄바닥재가 토양 처리 유기물의 이산화탄소 발생 저감 및 토양 탄소격리에 긍정적으로 기여 할 수 있는 소재로서 가능성이 있음을 보여준다. Disposal of high amount of coal combustion by-products, such as fly ash and bottom ash, is of a great concern to the country, due to the huge treatment cost and land requirement. On the other hand, those coal-ash wastes are considered to have desirable characteristics that may improve physical, chemical, and biological properties of soils. Especially, compared with fly ash, bottom ash has a larger particle size, porous surface area, and usable amount of micronutrients. In the present study, we examined bottom as a soil amendment for mitigating CO₂ emission and enhancing carbon sequestration in soils fertilized with organic matter (hairy vetch, green barely, and oil cake fertilizer). Through laboratory incubation, CO₂ released from the soil was quantitatively and periodically monitored with an enforced-aeration and high-temperature respirometer. We observed that amendment of bottom ash led to a marked reduction in CO₂ emission rate and cumulative amount of CO₂ released, which was generally proportional to the amount of bottom ash applied. We also found that the temporal patterns of CO₂ emission and C sequestration effects were partially dependent on the relative of proportion labile carbon and C/N ratio of the organic matter. Our results strongly suggest that amendment of bottom ash has potential benefits for fixing labile carbon as more stable soil organic matter, unless the bottom ash contains toxic levels of heavy metals or other contaminants.
교류전기장이 인가된 전선위에서 전선 끝단 근처의 화염전파 거동
황상석(Sang Seok Hwang),김민국(Min Kuk Kim),박정(Jeong Park),정석호(Suk Ho Chung),권오붕(Oh Boong Kwon) 한국연소학회 2012 KOSCOSYMPOSIUM논문집 Vol.- No.44
Experiments have been conducted to clarify flame spread behavior over electrical wire near the end of wire with applied AC electric fields. It is seen that the flame spread behavior near the end of wire with applied AC electric fields are quite different from that in temporally linearly-increasing flame position. The flame spread behavior can be categorized into three regimes based on the relevance of flame shape and the slanted direction of spread flame to spread rate. Detailed explanations on the characteristics are made through thermal balance mechanism. Also, the effect of drop of molten PE and fuel vapor-jet in flame spread is also discussed.
이충훈,정영호,정석호,Lee, Chung-Hun,Jeong, Yeong-Ho,Jeong, Seok-Ho 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.1
Mixing process of impinging jets of liquid oxidizer and liquid fuel is simulated by using water and sodium carbonate (Na$_{2}$CO$_{3}$) solution. The shapes of liquid sheets are visualized and flowrate distributions are measured by collecting droplets using measuring cells. Mixing charateristics are studied by using acid-base titration. Stable liquid sheets are formed and two liquid jets are well mixed for symmetric impinging jets. Similarity in flowrate distribution for various measuring heights is observed. For asymmetric impinging jets, liquid sheets become unstable as the difference in the velocities of jets increases. In some extreme cases, liquid sheets are not formed and the jets are separated. Dimensionless variables are adopted demonstrating similarly in flowrate distribution. Mixing characteristics vary significantly with experiment conditions.