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Kavitha 보안공학연구지원센터 2016 International Journal of Software Engineering and Vol.10 No.6
At the present time, computerized tests are one of the most critical means to evaluate learning. Choosing tailored questions for each learner is a important part of such tests. Since, wide and varied learners with different abilities are involved, even randomized test cannot serve the purpose of assessment. Some form of personalized and intelligent testing is needed in E-Learning. One of the main components in composing intelligent testing is selecting the items from a huge Item Bank as the accuracy of the test depends on the quality of the assessment which in turn depends on the items selected for assessment. Furthermore, pickingappropriate items is critical in developing as assessment sheet that satisfies multiple criteria. It includes the number of test items, the definitedissemination of course concepts to be assessed, and the expected degree of difficultness and discrimination and exposure frequency. These tests, must effectively select questions from a large item bank, and to manage this problem an optimized assessment sheet composition system using the modified form of nature inspired Intelligent Water Drops optimization algorithm is proposed by embedding a local heuristic as evolutionary operator. This system is designed to choosepersonalizedtest items for each and every learner. Furthermore, the proposed approach is able to effectively generate near optimal items from large item bank that satisfy multiple constraints. The results show that the Evolutionary Intelligent Water Drops approach is suitable for the selection of nearoptimal items from large-scale item bank.
Kavitha, S.,Rajesh Banu, J.,Subitha, G.,Ushani, U.,Yeom, I.T. Elsevier Applied Science 2016 Bioresource technology Vol.219 No.-
The objective of this study was to determine the impact of solubilization during thermo-chemo-sonic pretreatment of waste activated sludge (WAS) on anaerobic biodegradability and cost for biogas production. The results revealed that it was possible to achieve 40-50% of solubilization of WAS when ultrasonic energy input was doubled (11,520-27,000kJ/kgTS). The cost to achieve 30-35% of solubilization of WAS was calculated to be 0.22-0.24USD/L, which was relatively lower than the cost of 0.53-0.8USD/L when 40-50% of solubilisation of WAS was achieved. There was no significant difference in biodegradability (0.60-0.64gCOD/gCOD) for samples with solubilization efficiency of 35-50%. Comparing energetic balance and economic assessment of samples with different solubilization percentages, the results showed that samples with 30-35% of solubilization had lower net cost (7.98-2.33USD/Ton of sludge) and negative energy balance compared to samples with other percentages of solubilization.
Kavitha Hassan,김상훈,박인수,이선희,김수희,정영미,김상헌,김수현 한국고분자학회 2011 Macromolecular Research Vol.19 No.2
Tubular double layered scaffolds were fabricated using a biodegradable and elastic polymer, poly(L-lactide-co-ε-caprolactone) (PLCL, 50:50), which was comprised of an outer fibrous gel spun layer and inner porous dip coated layer. The mechanical properties were evaluated and compared with a rabbit aorta and expanded poly-tetrafluoroethylene (ePTFE). The PLCL scaffolds had circumferentially stronger tensile stress than the rabbit aorta and ePTFE graft, and its longitudinal stress was similar to a rabbit aorta but weaker than ePTFE. The E-modulus of the PLCL scaffold was significantly lower than that of ePTFE but significantly higher than that of the native rabbit aorta,this result was reversible in the case of compliance. There was no significant difference in suture retention strength and burst pressure compared to ePTFE grafts. The scaffolds were seeded with SMCs and cultured under dynamic conditions for 13 days to evaluate the cellularity. After a 13 day dynamic culture, the scaffolds showed efficient cell proliferation. Overall, the double layer small diameter PLCL scaffolds exhibited favorable mechanical strength even at a high pressure and good cellularity under dynamic conditions.
Kavitha, Anbukumar,Uma, Govindarajan The Korean Institute of Electrical Engineers 2010 Journal of Electrical Engineering & Technology Vol.5 No.1
Resonant parametric perturbation (RPP) method is an effective non-feedback method for controlling chaos. In this paper, the above method is applied for the current programmed buck-boost dc-dc converter which exhibits chaotic for wide parameter variations. The different possible operating regimes leading to chaotic operation of the current mode controlled buck-boost converter is discussed and the control of chaos by RPP method is demonstrated through computer simulations and experimental studies. The converter is stabilized to period 1 operation practically.
Kavitha, S.,Rajesh Banu, J.,Kumar, Gopalakrishnan,Kaliappan, S.,Yeom, Ick Tae Elsevier 2018 Bioresource technology Vol.254 No.-
<P><B>Abstract</B></P> <P>In this study, microwave irradiation has been employed to disintegrate the sludge biomass profitably by deagglomerating the sludge using a mechanical device, ultrasonicator. The outcomes of the study revealed that a specific energy input of 3.5 kJ/kg TS was found to be optimum for deagglomeration with limited cell lysis. A higher suspended solids (SS) reduction and biomass lysis efficiency of about 22.5% and 33.2% was achieved through ultrasonic assisted microwave disintegration (UMWD) when compared to microwave disintegration – MWD (15% and 20.9%). The results of biochemical methane potential (BMP) test were used to estimate biodegradability of samples. Among the samples subjected to BMP, UMWD showed better amenability towards anaerobic digestion with higher methane production potential of 0.3 L/g COD representing enhanced liquefaction potential of disaggregated sludge biomass. Economic analysis of the proposed method of sludge biomass pretreatment showed a net profit of 2.67 USD/Ton respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Floc deagglomeration happens significantly at 3.5 kJ/kg TS of ultrasonic energy. </LI> <LI> Biomass lysis efficiency of 33.2% was achieved in phase separated disintegration. </LI> <LI> Phase separation shows better amenability towards anaerobic biodegradation. </LI> <LI> Net profit of about 2.67 USD/Ton was achieved in phase separated disintegration. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Characterization of a Putative Thioredoxin Peroxidase Prx1 of Candida albicans
Kavitha Srinivasa,최원자,Na-Rae Kim,Jiwon Kim,Minsun Kim,Ju Yun Bae,정우진,김완기 한국분자세포생물학회 2012 Molecules and cells Vol.33 No.3
In this study, we characterized a putative peroxidase Prx1 of Candida albicans by: 1) demonstrating the thiore-doxin-linked peroxidase activity with purified proteins, 2) examining the sensitivity to several oxidants and the accumulation of intracellular reactive oxygen species with a null mutant (prx1∆), a mutant (C69S) with a point mutation at Cys69, and a revertant, and 3) subcelluar localization. Enzymatic assays showed that Prx1 is a thioredoxin-linked peroxidase which reduces both hydrogen peroxide (H2O2) and tert-butyl hydroperoxide (t-BOOH). Compared with two other strong H2O2 scavenger mutants for TSA1 and CAT1, prx1∆ and C69S were less sensitive to H2O2, menadione and diamide at all concentrations tested, but were more sensitive to low concentration of t-BOOH. Intracellular reactive oxygen species accumulated in prx1∆ and C69S cells treated with t-BOOH but not H2O2. These results suggest that peroxidase activity of Prx1 is specified to t-BOOH in cells. In both biochemical and physiological cases, the evolutionarily conserved Cys69 was found to be essential for the function. Immunocytochemical staining revealed Prx1 is localized in the cytosol of yeast cells, but is translocated to the nucleus during the hyphal transition, though the significances of this observation are unclear. Our data suggest that PRX1 has a thioredoxin peroxidase activity reducing both t-BOOH and H2O2, but its cellular function is specified to t-BOOH.
Pharmacophore Modeling for Protein Tyrosine Phosphatase 1B Inhibitors
Kavitha Bharatham,이근우,Nagakumar Bharatham 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.5
A three dimensional chemical feature based pharmacophore model was developed for the inhibitors of protein tyrosine phosphatase 1B (PTP1B) using the CATALYST software, which would provide useful knowledge for performing virtual screening to identify new inhibitors targeted toward type II diabetes and obesity. A dataset of 27 inhibitors, with diverse structural properties, and activities ranging from 0.026 to 600 µM, was selected as a training set. Hypo1, the most reliable quantitative four featured pharmacophore hypothesis, was generated from a training set composed of compounds with two H-bond acceptors, one hydrophobic aromatic and one ring aromatic features. It has a correlation coefficient, RMSD and cost difference (null cost-total cost) of 0.946, 0.840 and 65.731, respectively. The best hypothesis (Hypo1) was validated using four different methods. Firstly, a cross validation was performed by randomizing the data using the Cat-Scramble technique. The results confirmed that the pharmacophore models generated from the training set were valid. Secondly, a test set of 281 molecules was scored, with a correlation of 0.882 obtained between the experimental and predicted activities. Hypo1 performed well in correctly discriminating the active and inactive molecules. Thirdly, the model was investigated by mapping on two PTP1B inhibitors identified by different pharmaceutical companies. The Hypo1 model correctly predicted these compounds as being highly active. Finally, docking simulations were performed on few compounds to substantiate the role of the pharmacophore features at the binding site of the protein by analyzing their binding conformations. These multiple validation approaches provided confidence in the utility of this pharmacophore model as a 3D query for virtual screening to retrieve new chemical entities showing potential as potent PTP1B inhibitors.
Kavitha Nagarasampatti Palani,Nithya Ramasamy,Kamalakannan Vasantha Palaniappan,허윤석,Balasubramanian Natesan 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.76 No.-
This work focus to alleviate the fouling in Membrane bioreactor (MBR) by integrating electrooxidation,adsorptive cake, bio-film carriers and ozonation referred as Integrated Moving Bed Bioreactor (IMBBR). The total organic carbon (TOC), Chemical Oxygen Demand (COD) and Total Dissolved Solids (TDS)removal were observed as above 95%, 95% and 70% at 300 kPa with theflux increase in 35%. The numericalmodel was developed which proved less fouling which was in agreement with Scanning electronmicroscopy (SEM) and Liquid Chromatography and Mass Spectroscopy (LCMS). This study showed lessenergy consumption without the problem offilamentous bulking.
Enhancement of biogas production from microalgal biomass through cellulolytic bacterial pretreatment
Kavitha, S.,Subbulakshmi, P.,Rajesh Banu, J.,Gobi, Muthukaruppan,Tae Yeom, Ick Elsevier 2017 Bioresource technology Vol.233 No.-
<P><B>Abstract</B></P> <P>Generation of bioenergy from microalgal biomass has been a focus of interest in recent years. The recalcitrant nature of microalgal biomass owing to its high cellulose content limits methane generation. Thus, the present study investigates the effect of bacterial-based biological pretreatment on liquefaction of the microalga <I>Chlorella vulgaris</I> prior to anaerobic biodegradation to gain insights into energy efficient biomethanation. Liquefaction of microalgae resulted in a higher biomass stress index of about 18% in the experimental (pretreated with cellulose-secreting bacteria) vs. 11.8% in the control (non-pretreated) group. Mathematical modelling of the biomethanation studies implied that bacterial pretreatment had a greater influence on sustainable methane recovery, with a methane yield of about 0.08 (g Chemical Oxygen Demand/g Chemical Oxygen Demand), than did control pretreatment, with a yield of 0.04 (g Chemical Oxygen Demand/g Chemical Oxygen Demand). Energetic analysis of the proposed method of pretreatment showed a positive energy ratio of 1.04.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microalgal biomass pretreatment by bacteria enhances liquefaction of about 18%. </LI> <LI> Bacterial pretreatment increases the macromolecular release considerably. </LI> <LI> Experimental microalgae improves the methane to 0.08gCOD/gCOD comparing to control. </LI> <LI> Methane production rate increased with hydrolysis constant of about 0.24day<SUP>−1</SUP>. </LI> <LI> A positive energy ratio of about 1.04 was achieved in experimental microalgae. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>