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Recent Research on the Local Buckling of Cold-formed Stainless Steel Sections
K J R Rasmussen,T Burns,P Bezkorovainy,M R Bambach 한국강구조학회 2005 International Journal of Steel Structures Vol.5 No.1
Research at the University of Sydney in the stainless steel area has for the last four years concentrated on the local bucklingstrength of stainless steel plates with aplication to cold-formed sections. The research has encompassed tests on single stainlessvesfor stainles steel materials over the full strain range solely in terms of the Ramberg-Osgood parameters (n, σ0.2, E0). Advancedfinite element models have been used to derive direct expressions for the plate strength in terms of the Ramberg-Osgoodparameters using a modified Winter curve. The explicit plate strength equations showed that as a result of gradual yielding,the strength of stainless steel plates is reduced below the strength of carbon stel plates, as predicted by the standard Winteraplied to cold-formed sections and design models were proposed for determining the strength of such sections. It was shownthat the corners of cold-formed sections play a more important role for stainless steel sections than for carbon steel sectionsbecause the corner areas can be cold-worked to much higher strengths than in the case of carbon steel sections. Because ofthe enhanced mechanical properties of the corners, the standard Winter equation can in many cases be used safely for the designof cold-formed stainless steel sections. There are however a number of exceptions, which have ben identified. The present
양돈액비에서 Struvite 형성으로 연속적 인의 회수기술
오인환,이종현,최병현,Oh I.H.,Lee J.H.,Choi B.H.,Burns R.T. 한국축산환경학회 2006 축산시설환경학회지 Vol.12 No.2
양돈액비에서 인을 회수하기 위한 연속식 공정을 개발하고자 시험을 수행하였다. $MgCl_2$를 마그네슘 원으로 사용하였고 pH를 NaOH로 조정해준 구와 폭기를 시켜준 구를 서로 비교하였다. 몰비가 증가할수록 용해인의 회수율도 증가함을 알 수 있었다. 1. pH를 NaOH로 조정하였을 때 비육돈사 액비의 경우에 용해인은 몰비 1:1.5에서 초기값 353(${\pm}9$)mg/L에서 19(${\pm}1.6$)mg/L로 감소하여 95%의 회수효과를 보았으며, 암모니아성 질소의 경우에는 5,527(${\pm}174$)mg/L에서 5,009(${\pm}161$)mg/L로 감소하여 9%의 제거율을 나타내었다. 2. 자돈사 액비의 경우에 몰비 1:1.5에서 용해인은 초기치 111(${\pm}2.8$)mg/L에서 1(${\pm}1.1$)mg/L로 감소하여 회수율은 98%를 나타내었으며, 암모니아성 질소의 경우에는 2,317 (${\pm}37$)mg/L에서 2,226(${\pm}39$)mg/L으로 감소하여 제거율 4%를 나타내었다. 3. 자돈사 액비의 경우에 폭기공정의 몰비 1:1.5에서 용해인은 초기값 321(${\pm}10.2$)mg/L에서 113(${\pm}3.6$)mg/L로 감소하여 회수율은 66%로 되었으며, 암모니아성 질소의 경우에는 2,364(${\pm}5$)mg/L에서 2,017(${\pm}2$)mg/L로 낮아져서 제거율은 15%로 높게 나타났다. 4. pH를 NaOH로 조정해준 구가 폭기를 시켜준 구보다 용해인 회수에서 효과가 좋았다. 암모니아성 질소의 제거에서는 반대로 폭기구에서 높게 나타났다. This study was carried out to develop a continuous process for recovering phosphorus in swine slurry. Magnesium chloride ($MgCl_2$) was used in the test as a magnesium source and the pH was regulated by adding NaOH and aerating. The results showed that the recovery rate of soluble phosphorus (SP) has increased with the molar ratios increased. In case of pH regulated with NaOH, the recovery rates of SP with molar ratio of 1:1.5 were over 95% from both farms. The removal of ammonia-nitrogen was at levels of $4{\sim}9%$. With aeration treatment, the SP recovery rate was 66% and the removal rate of ammonia-nitrogen was 15%. The treatment of NaOH to increase pH showed better SP recovery efficiency than the aeation treatment. However, in case of ammonia-nitrogen removal, the treatment of aeration showed better results than the NaOH treatment.