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Kaliyappan Karthikeyan,Samuthirapandian Amaresh,Ju-Nam Son,Shin-Ho Kim,Min-Chul Kim,김광진,이윤성,Sol-Nip Lee 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.1
Layered Li1+x(Mn0.4Ni0.4Fe0.2)1-xO2 (0 < x < 0.3) solid solutions were synthesized using solgel method with adipic acid as chelating agent. Structural and electrochemical properties of the prepared powders were examined by means of X-ray diffraction, Scanning electron microscopy and galvanostatic charge/discharge cycling. All powders had a phase-pure layered structure with R3m space group. The morphological studies confirmed that the size of the particles increased at higher x content. The charge-discharge profiles of the solid solution against lithium using 1 M LiPF6 in EC/DMC as electrolyte revealed that the discharge capacity increases with increasing lithium content at the 3a sites. Among the cells, Li1.2(Mn0.32Ni0.32Fe0.16)O2 (x = 0.2)/ Li+ exhibits a good electrochemical property with maximum initial capacity of 160 mAhg−1 between 2-4.5 V at 0.1 mAcm−2 current density and the capacity retention after 25 cycles was 92%. Whereas, the cell fabricated with x = 0.3 sample showed continuous capacity fading due to the formation of spinel like structure during the subsequent cycling. The preparation of solid solutions based on LiNiO2-LiFeO2-Li2MnO3 has improved the properties of its end members.
Kaliyappan, Kannan,Padmanabhan, Sutha The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.2
This paper presents a novel nonlinear model of Switched Reluctance Generator (SRG) based on wind Energy Conversion system. Closed loop control with based Proportional Integrator current Chopping Control machine model is used. A Power converter in SRG can be controlled by using PI-CCC proposed model, and can be produced maximum power efficiency and minimize the ripple contents in the output of SRG. A second power converter namely PI based controlled PWM Inverter is used to interface the machine to the Grid. An effective control technique for the inverter, based on the pulse width modulation (PWM) scheme, has been developed to make the line voltage needs less power switching devices and each pair of turbine the generated active power starts increasing smoothly. This proposed control scheme feasibility and validity are simulated on SIMULINK/SIM POWER SYSTEMS only.
Kannan Kaliyappan,Sutha Padmanabhan 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.2
This paper presents a novel nonlinear model of Switched Reluctance Generator (SRG) based on wind Energy Conversion system. Closed loop control with based Proportional Integrator current Chopping Control machine model is used. A Power converter in SRG can be controlled by using PI-CCC proposed model, and can be produced maximum power efficiency and minimize the ripple contents in the output of SRG. A second power converter namely PI based controlled PWM Inverter is used to interface the machine to the Grid. An effective control technique for the inverter, based on the pulse width modulation (PWM) scheme, has been developed to make the line voltage needs less power switching devices and each pair of turbine the generated active power starts increasing smoothly. This proposed control scheme feasibility and validity are simulated on SIMULINK/SIM POWER SYSTEMS only.
Karthikeyan, Kaliyappan,Amaresh, Samuthirapandian,Lee, Sol-Nip,An, Jae-Yeon,Lee, Yun-Sung Wiley-VCH 2014 CHEM SUS CHEM Vol.7 No.8
<P>LiMnBO3 nanobeads (LMB-NB) with uniform size and distribution were synthesized using a urea-assisted microwave/solvothermal method. The potential application of LMB-NBs as an anode for a lithium-ion hybrid capacitor (Li-AHC) was tested with a polyaniline-nanofiber (PANI-NF) cathode in a nonaqueous LiPF6 (1?M)-ethylene carbonate/dimethyl carbonate electrolyte. Cyclic voltammetry (CV) and charge-discharge (C/DC) studies revealed that the PANI-NF/LMB-NB cell showed an exceptional capacitance behavior between 0-3 V along with a prolonged cycle life. A discharge capacitance of about 125 F g(-1) , and energy and power densities of about 42 Wh kg(-1) and 1500 W kg(-1) , respectively, could be obtained at a current density of 1 A g(-1) ; those Li-AHC values are higher relative to cells containing various lithium intercalation materials in nonaqueous electrolytes. In addition, the PANI-NF/LMB-NB cell also had an outstanding rate performance with a capacitance of 54 F g(-1) and a power density of 3250 W kg(-1) at a current density of 2.25 A g(-1) and maintained 94% of its initial value after 30000 cycles. This improved capacitive performance with an excellent electrochemical stability could be the result of the morphological features and inherent conductive nature of the electroactive species.</P>
Karthikeyan, Kaliyappan,Amaresh, Samuthirapandian,Son, Ju-Nam,Kim, Shin-Ho,Kim, Min-Chul,Kim, Kwang-Jin,Lee, Sol-Nip,Lee, Yun-Sung Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.1
Layered $Li_{1+x}(Mn_{0.4}Ni_{0.4}Fe_{0.2})_{1-x}O_2$ (0 < x < 0.3) solid solutions were synthesized using solgel method with adipic acid as chelating agent. Structural and electrochemical properties of the prepared powders were examined by means of X-ray diffraction, Scanning electron microscopy and galvanostatic charge/discharge cycling. All powders had a phase-pure layered structure with $R\bar{3}m$ space group. The morphological studies confirmed that the size of the particles increased at higher x content. The charge-discharge profiles of the solid solution against lithium using 1 M $LiPF_6$ in EC/DMC as electrolyte revealed that the discharge capacity increases with increasing lithium content at the 3a sites. Among the cells, $Li_{1.2}(Mn_{0.32}Ni_{0.32}Fe_{0.16})O_2$ (x = 0.2)/$Li^+$ exhibits a good electrochemical property with maximum initial capacity of 160 $mAhg^{-1}$ between 2-4.5 V at 0.1 $mAcm^{-2}$ current density and the capacity retention after 25 cycles was 92%. Whereas, the cell fabricated with x = 0.3 sample showed continuous capacity fading due to the formation of spinel like structure during the subsequent cycling. The preparation of solid solutions based on $LiNiO_2-LiFeO_2-Li_2MnO_3$ has improved the properties of its end members.
Karthikeyan, Kaliyappan,Amaresh, Samuthirapandian,Lee, Sol Nip,Aravindan, Vanchiappan,Lee, Yun Sung Wiley-VCH 2014 Chemistry - An Asian Journal Vol.9 No.3
<P>Nanostructured α-Fe2 O3 with and without fluorine substitution were successfully obtained by a green route, that is, microwave irradiation. The hematite phase materials were evaluated as a high-performance electrode material in a hybrid supercapacitor configuration along with activated carbon (AC). The presence of fluorine was confirmed through X-ray photoelectron spectroscopy and transmission electron microscopy. Fluorine-doped Fe2 O3 (F-Fe2 O3 ) exhibits an enhanced pseudocapacitive performance compared to that of the bare hematite phase. The F-Fe2 O3 /AC cell delivered a specific capacitance of 71?F?g(-1) at a current density of 2.25?A?g(-1) and retained approximately 90?% of its initial capacitance after 15?000?cycles. Furthermore, the F-Fe2 O3 /AC cell showed a very high energy density of about 28?W?h?kg(-1) compared to bare hematite phase (9?W?h?kg(-1) ). These data clearly reveal that the electrochemical performance of Fe2 O3 can be improved by fluorine doping, thereby dramatically improving the energy density of the system.</P>
Karthikeyan, Kaliyappan,Amaresh, Samuthirapandiyan,Lee, Sol Nip,Sun, Xueliang,Aravindan, Vanchiappan,Lee, Young-Gi,Lee, Yun Sung Wiley-VCH 2014 CHEM SUS CHEM Vol.7 No.5
<P>Very high surface area activated carbons (AC) are synthesized from pine cone petals by a chemical activation process and subsequently evaluated as an electrode material for supercapacitor applications in a nonaqueous medium. The maximum specific surface area of 3950?m(2) ?g(-1) is noted for the material treated with a 1:5 ratio of KOH to pine cone petals (PCC5), which is much higher than that reported for carbonaceous materials derived from various other biomass precursors. A symmetric supercapacitor is fabricated with PCC5 electrodes, and the results showed enhanced supercapacitive behavior with the highest energy density of 61?Wh?kg(-1). Furthermore, outstanding cycling ability is evidenced for such a configuration, and 90?% of the initial specific capacitance after 20,000?cycles under harsh conditions was observed. This result revealed that the pine-cone-derived high-surface-area AC can be used effectively as a promising electrode material to construct high-energy-density supercapacitors.</P>
PalanivelVelmurugan,Kaliyappan Amballandi Vedhanayakisri,박율진,진종식,오병택 한국섬유공학회 2019 Fibers and polymers Vol.20 No.2
The core purpose of this study was to extract natural dye from Aronia melanocarpa (black chokeberry) powder (BCP) via soxhlet extraction or ultrasound water bath using acidified ethanol (A. EtOH) as the extraction solvent. After optimization of the dye extraction conditions, high color intensity was achieved at pH 4, temperature of 80 ℃, 40 and 90 mlof A. EtOH, 2 g of BCP, time of 80 and 90 min, ultrasonic output power of 75 W or 6 extraction cycles for ultrasonic water bath and soxhlet extraction, respectively. The extracted red natural dye (BCP) was used alone or together with commercial silver nanoparticles (C-AgNPs) to dye cotton, silk, and leather in an eco-friendly approach without using any external chemicals with augmented antibacterial activity. Rotary vacuum dyeing yielded excellent dyeing and the optimal conditions for high color strength (K/S) values were pH 4, 120 min at 80 ℃ for cotton and silk and 90 min at 60 ℃ for leather. Morphologies of dyed cotton, silk, and leather and the anchoring of C-AgNPs with elemental compositions were investigated by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS). The dry and wet rubbing fastness values for dye alone and dye with nanoparticles were grade 4-5 and 4, respectively.
Padmanabhan, Sutha,Kaliyappan, Kannan The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.1
A wind generator (WG) maximum power point tracking (MPPT) system is presented here. It comprises of a variable-speed wind generator, a high-efficiency boost-type dc/dc converter and a control unit. The advantages of the aimed system are that it does not call for the knowledge of the wind speed or the optimal power characteristics and that it operates at a variable speed, thus providing high efficiency. The WG operates at variable speed and thus suffers lower stress on the shafts and gears compared to constant-speed systems. It results in a better exploitation of the available wind energy, especially in the low wind-speed range of 2.5-4.5 m/s. It does not depend on the WG wind and rotor-speed ratings or the dc/dc converter power rating. Higher reliability, lower complexity and cost, and less mechanical stress of the WG. It can be applied to battery-charging applications.