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Analysis and Modeling of Heterogeneous Gas-Liquid Dynamic Flow in a Bubble Column
강용,김상도,윤석호,심정섭,고명한 忠南大學校 産業技術硏究所 1994 산업기술연구논문집 Vol.9 No.2
A bubble column has a wide range of applications as chemical or biochemical reactors because of their numerous advantages. Its internal structure is complex and heterogeneous; thus, it must be characterized by numerous parameters, such as gas holdup, frequency of bubble formation, size of bubbles, dispersion coeffcients in the gas and liquid phases, and gas-liquid interfacial area. These parametes can not be easily manipulated because of the apparently random and irregular motion of the bubbles in the column. This irregular motion of bubbles may induce not only pressure fluctuations but also non-uniform flow or distribution of bubbles in the column, which is a major cause of deterioration in the performance of a bubble-column reactor. In the present study, the non-uniformity of bubble flow has been investigated through spectral analysis of the pressure fluctuations. Specifically, the non-uniform bubble flow has been analyzed in terms of periodic and stochastic (or random) components of the pressure fluctuation signals.
강용,김상도,조승호,윤석호,김영주 忠南大學校 産業技術硏究所 1994 산업기술연구논문집 Vol.9 No.1
제트밀에서 입자의 유동화는 밀의 분쇄효율을 높여주는 것으로 알려져 왔다. 파이롯트 규모의 유동충 제트밀에서 분쇄되는 입자의 흐름특성을 예측하기 위하여 압력변동을 측정하였으며 이를 통계적 방법에 의하여 분석하였다. 또한 분쇄유체와 유동화유체의 압력 또는 밀도의 영향 및 압력변동에 대한 밀 내부에서의 반경 방향 및 높이 변화에 따라 흐름 특성을 설명하였다. 유동충 제트밀에서 유입유체의 압력이 증가할수록 내부의 압력은 증가하였고, 압력변동의 분산은 증가한 반면 압력변동의 비대칭도와 첨도는 감소함을 알 수 있었다. Fluidization of the particles in a jet mill has been proposed to enhance the comminution efficiency of the mill. Characteristic of pressure fluctuations has analyzed by means of statistical method to predict the flow behavior of particles comminuted in a fluidized-bed jet mill of pilot plant scale. Effects of the pressure or the density of pulverizing-air and fluidizing-air and the position interior of the chamber of the mill on the pressure fluctuations have been examined. It has been found that the variance of the pressure fluctuations has increased while the skewness and kurtosis have decreased with an increase of the pressure or density of the fluidizing-air.
Yoon, Ok J.,Kim, Hyun W.,Kim, Duck J.,Lee, Hyun J.,Yun, Ji Y.,Noh, Yoo H.,Lee, Do Y.,Kim, Do H.,Kim, Sung S.,Lee, Nae-Eung WILEY-VCH Verlag 2009 Plasma Processes and Polymers Vol.6 No.2
<P>The conductance of amine-functionalized SWCNTs (a-SWCNTs), obtained by inductively coupled N<SUB>2</SUB>/H<SUB>2</SUB> plasma treatment of commercially available carboxyl-functionalized SWCNTs (c-SWCNTs), was decreased compared to that of the c-SWCNTs. As a result, the diameter and surface energy of electrospun PLGA/a-SWCNT nanocomposites decreased and increased, respectively, compared to those of electrospun PLGA/c-SWCNT nanocomposites. The results also showed that the a-SWCNTs were well dispersed in the nanocomposites, improved adhesion of SWCNTs to the surrounding polymer matrix and thereby enhanced the tensile modulus of electrospun PLGA/c-SWCNT and PLGA/a-SWCNT nanocomposites by 127 and 226%, respectively, compared to that of electrospun PLGA membranes.</P><P> <img src='wiley_img/16128850-2009-6-2-PPAP200800081-gra001.gif' alt='wiley_img/16128850-2009-6-2-PPAP200800081-gra001'> </P>
Kim, Y. C.,Do, J. E.,Bang, D.,Cho, B. K.,Cho, K. H.,Choi, J. C.,Kim, M. B.,Kim, M. H.,Kim, S. Y.,Kim, S. N.,Lee, J. H.,Lee, S. J.,Shin, D. H.,Shin, J. H.,Son, S. J.,Suh, K. S.,Yoon, T. Y.,Park, C. K. Blackwell Publishing Ltd 2010 Clinical and experimental dermatology Vol.35 No.2
<P>Summary</P><P>Background. </P><P>Spitz naevi have not been widely studied in Asians.</P><P>Aim. </P><P>To compare the epidemiology and clinicopathological features of Spitz naevi in Koreans with lesions in western countries.</P><P>Methods. </P><P>In total, 80 Spitz naevi in 77 patients diagnosed over 10 years at 17 university hospitals in Korea were analysed.</P><P>Results. </P><P>The relative incidence of Spitz naevus vs. MM was 1 vs. 10.9. In most patients (75%) the Spitz naevi had been present for > 6 months. The size of the lesion was relatively large. Histologically, most of the lesions (54%) were the dermal type and pigmentation was common (49% of lesions). Immunohistochemical study found that all of the 34 lesions were positive for S-100 protein but only 14 (47%) were positive for HMB-45.</P><P>Conclusion. </P><P>Spitz naevus is rare in Korea. The lesions were more commonly larger, pigmented, and of the dermal type than reported in western countries.</P>