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An ultra-precision magnetic abrasive finishing (UPMAF) process is an efficient mirror finishing technique. This research utilized the ultra-precision magnetic abrasive finishing technique to improve the accuracy of advanced material of Inconel alloy 625 cylindrical bars. The finishing technique employed flexible unbonded magnetic abrasive tools with neodymium permanent magnets (Nd-Fe-B), and components of the finishing procedure were installed with a five-dimensional computer numerical control (CNC) machining center. The surface accuracy and dimensional accuracy of Inconel alloy 625 bars were enhanced by the ultra-precision magnetic abrasive finishing technique with input parameters of workpiece rotational speed, work-piece feed rate, and magnetic abrasive grain size. After characterization with energy dispersive X-ray analysis (EDX), atomic force microscope (AFM), and a thermal imaging camera, we found that this ultra-precision magnetic polishing technology can improve surface roughness Ry of Inconel alloy 625 cylindrical bars from 2010 nm to 200 nm at a rotational speed of 12000 rpm, feed rate of 2000 mm/min, diamond abrasive grain size of 1 µm, and flux density of 300 mT processing of 5 min.
Jung Tak Bae; Han Joo Kim. Finishing characteristics of Inconel alloy 625 bars in ultra-precision magnetic abrasive finishing using CNC machine center. Journal of Mechanical Science and Technology 2021, 1 -9.
AMA StyleJung Tak Bae, Han Joo Kim. Finishing characteristics of Inconel alloy 625 bars in ultra-precision magnetic abrasive finishing using CNC machine center. Journal of Mechanical Science and Technology. 2021; ():1-9.
Chicago/Turabian StyleJung Tak Bae; Han Joo Kim. 2021. "Finishing characteristics of Inconel alloy 625 bars in ultra-precision magnetic abrasive finishing using CNC machine center." Journal of Mechanical Science and Technology , no. : 1-9.
The wide use of manganese dioxide (MnO2) as an electrode in all-solid-state asymmetric supercapacitors (ASCs) remains challenging because of its low electrical conductivity. This complication can be circumvented by introducing trivalent gadolinium (Gd) ions into the MnO2. Herein, we describe the successful hydrothermal synthesis of crystalline Gd-doped MnO2 nanorods with Ni(OH)2 nanosheets as cathode, which we combined with Fe3O4/GO nanospheres as anode for all-solid-state ASCs. Electrochemical tests demonstrate that Gd doping significantly affected the electrochemical activities of the MnO2, which was further enhanced by introducing Ni(OH)2. The GdMnO2/Ni(OH)2 electrode offers sufficient surface electrochemical activity and exhibits excellent specific capacity of 121.8 mA h g-1 at 1 A g-1, appealing rate performance, and ultralong lifetime stability (99.3% retention after 10,000 discharge tests). Furthermore, the GdMnO2/Ni(OH)2//PVA/KOH//Fe3O4/GO solid-state ASC device offers an impressive specific energy density (60.25 W h kg-1) at a high power density (2332 W kg-1). This investigation thus shows its large potential in developing novel approaches to energy storage devices.
Milan Babu Poudel; Han Joo Kim. Synthesis of high-performance nickel hydroxide nanosheets/gadolinium doped-α-MnO2 composite nanorods as cathode and Fe3O4/GO nanospheres as anode for an all-solid-state asymmetric supercapacitor. Journal of Energy Chemistry 2021, 64, 475 -484.
AMA StyleMilan Babu Poudel, Han Joo Kim. Synthesis of high-performance nickel hydroxide nanosheets/gadolinium doped-α-MnO2 composite nanorods as cathode and Fe3O4/GO nanospheres as anode for an all-solid-state asymmetric supercapacitor. Journal of Energy Chemistry. 2021; 64 ():475-484.
Chicago/Turabian StyleMilan Babu Poudel; Han Joo Kim. 2021. "Synthesis of high-performance nickel hydroxide nanosheets/gadolinium doped-α-MnO2 composite nanorods as cathode and Fe3O4/GO nanospheres as anode for an all-solid-state asymmetric supercapacitor." Journal of Energy Chemistry 64, no. : 475-484.
In this study, a wireless power transmission (WPT) system for high power was developed to supply the wirelessly powered transfer cart for a clean environment (such as liquid crystal display (LCD), semiconductor, and flat panel display (FPD) device industries) to improve the cleanliness of related industrial production lines and save energy. The power transmission method of WPT and the core design were optimized, and a shortened track was fabricated to enable WPT via short power lines for diverse applications in a small space-constrained workshop. In realizing the shortened Litz wire system, the amount of heat generated increased due to the increased resistance in the system, and efforts were made to improve the thermal performance. A simple approach was also proposed to estimate the skin depth caused by the skin effects in a cable made up of multiple strands of multiple wires, validated through thermal analysis by using ANSYS software in terms of heat generation by an electric field. Structure designs were implemented to improve the heat transfer performance, and the experimental results of WPT systems at a power level of 21.54 kW demonstrate that the power transfer distance of WPT was above 15 mm with a charging efficiency above 83.24%.
Jae Sik Jin; Sunghun Jung; Han Joo Kim. Development of Wireless Power Transmission System for Transfer Cart with Shortened Track. Applied Sciences 2020, 10, 4694 .
AMA StyleJae Sik Jin, Sunghun Jung, Han Joo Kim. Development of Wireless Power Transmission System for Transfer Cart with Shortened Track. Applied Sciences. 2020; 10 (14):4694.
Chicago/Turabian StyleJae Sik Jin; Sunghun Jung; Han Joo Kim. 2020. "Development of Wireless Power Transmission System for Transfer Cart with Shortened Track." Applied Sciences 10, no. 14: 4694.
We report a polyaniline-wrapped, manganese-doped titanium oxide (PANi/Mn-TiO2) nanoparticle composite for supercapacitor electrode and photocatalytic degradation. The PANi/Mn-TiO2 nanoparticles were synthesized using a solvothermal process, followed by oxidative polymerization of aniline. The structural properties of studied materials were confirmed by XRD, FTIR, HRTEM, FESEM, and UV visible spectroscopy. The as-prepared PANi/Mn-TiO2 nanoparticles revealed admirable electrochemical performance with a specific capacitance of 635.87 F g−1 at a current density of 1 A g−1 with a notable life cycle retention of 91% after 5000 charge/discharge cycles. Furthermore, the asymmetric cell with PANi/Mn-TiO2 as a positive electrode exhibited energy density of 18.66 W h kg−1 with excellent stability. Moreover, the PANi/Mn-TiO2 had promising photocatalytic activity for methylene blue degradation. The improved performance of PANi/Mn-TiO2 nanoparticles is attributed to the well-built synergetic effect of components that lead to significant reduction of band gap energy and charge transfer resistance, as revealed by UV visible spectroscopy and electrochemical impedance spectroscopy.
Milan Babu Poudel; Changho Yu; Han Joo Kim. Synthesis of Conducting Bifunctional [email protected] Nanocomposites for Supercapacitor Electrode and Visible Light Driven Photocatalysis. Catalysts 2020, 10, 546 .
AMA StyleMilan Babu Poudel, Changho Yu, Han Joo Kim. Synthesis of Conducting Bifunctional [email protected] Nanocomposites for Supercapacitor Electrode and Visible Light Driven Photocatalysis. Catalysts. 2020; 10 (5):546.
Chicago/Turabian StyleMilan Babu Poudel; Changho Yu; Han Joo Kim. 2020. "Synthesis of Conducting Bifunctional [email protected] Nanocomposites for Supercapacitor Electrode and Visible Light Driven Photocatalysis." Catalysts 10, no. 5: 546.
In the present study, mesoporous Mn doped TiO2 (Mn-TiO2) was synthesised by a simple sol–gel followed by solvothermal method. Brownish white powder is further characterised to confirm the synthesis of 40–50 nm sized high surface area mesoporous Mn-TiO2 nanoparticle. The electrochemical study by using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) revealed nearly 2-fold enhancement of capacitance and the carrier density compared to the pure TiO2 nanoparticle. This enhanced electrochemical property could be mainly ascribed to larger surface area, mesoporous structure and appropriate concentration of Mn doping that altered the optoelectronic properties of wide band gap TiO2.
Devi Prashad Ojha; Milan Babu Poudel; Han Joo Kim. Investigation of electrochemical performance of a high surface area mesoporous Mn doped TiO2 nanoparticle for a supercapacitor. Materials Letters 2020, 264, 127363 .
AMA StyleDevi Prashad Ojha, Milan Babu Poudel, Han Joo Kim. Investigation of electrochemical performance of a high surface area mesoporous Mn doped TiO2 nanoparticle for a supercapacitor. Materials Letters. 2020; 264 ():127363.
Chicago/Turabian StyleDevi Prashad Ojha; Milan Babu Poudel; Han Joo Kim. 2020. "Investigation of electrochemical performance of a high surface area mesoporous Mn doped TiO2 nanoparticle for a supercapacitor." Materials Letters 264, no. : 127363.
Spent alkaline battery powder representing as a mixture of metal oxides was applied to the polyacrylonitrile (PAN) template to convert the hydrophobic PAN membrane to hydrophilic. The interaction between the metal oxides on the resulting composite membrane and water molecules is sufficiently strong to allow instant passage of water through the membrane. Hence, this application should improve the oil-in-water emulsion filtration technique. A simple electrospinning technique was employed to fabricate the novel composite membrane of polyacrylonitrile matrix and spent alkaline battery powder under normal conditions. Surfactant-free oil-in-water emulsions were prepared using four common organic oils: n-hexane, toluene, gasoline, and diesel in the oil/water ratio of 3:7 v/v. Filtration processes were carried out under the gravity alone. The spent alkaline battery powder showed the physical interaction with PAN polymer fiber forming the superhydrophilic composite membrane. A membrane with higher amount of battery powder (1sBAT/PAN) showed about 2.1 times the water permeation flux for toluene in water emulsion compared to the membrane containing less amount of battery powder (0.5sBAT/PAN). The combination of waste battery powder with PAN polymer fiber is a useful technique for the oil separation technology.
Hem Prakash Karki; Laxmi Kafle; Han Joo Kim. Composite membrane of polyacrylonitrile and spent alkaline battery powder for filtration of oil-in-water emulsions. Microporous and Mesoporous Materials 2020, 297, 110026 .
AMA StyleHem Prakash Karki, Laxmi Kafle, Han Joo Kim. Composite membrane of polyacrylonitrile and spent alkaline battery powder for filtration of oil-in-water emulsions. Microporous and Mesoporous Materials. 2020; 297 ():110026.
Chicago/Turabian StyleHem Prakash Karki; Laxmi Kafle; Han Joo Kim. 2020. "Composite membrane of polyacrylonitrile and spent alkaline battery powder for filtration of oil-in-water emulsions." Microporous and Mesoporous Materials 297, no. : 110026.
Hydrothermally synthesized Zinc tungstate (ZnWO4, ZWO) nanorod with high aspect ratio is coupled with ZnO to design a photoactive ZnO/ZWO heterostructure. The morphological characterizations and surface measurements indicated ZnO nanoparticles embedded over well crystallized ZnWO4 nanorods thereby increasing specific surface area. The kinetic studies of the salicylic acid photodegradation showed the enhanced photoactivity of ZnO/ZWO heterostructure as compared to the individual nanostructures. This is attributed to the selective photoexcitation of the semiconductors that prolonged the lifetime of the charged species further confirmed by the conductivity measurements and trapping experiments.
Devi Prashad Ojha; Han Joo Kim. Investigation of photocatalytic activity of ZnO promoted hydrothermally synthesized ZnWO4 nanorods in UV–visible light irradiation. Chemical Engineering Science 2019, 212, 115338 .
AMA StyleDevi Prashad Ojha, Han Joo Kim. Investigation of photocatalytic activity of ZnO promoted hydrothermally synthesized ZnWO4 nanorods in UV–visible light irradiation. Chemical Engineering Science. 2019; 212 ():115338.
Chicago/Turabian StyleDevi Prashad Ojha; Han Joo Kim. 2019. "Investigation of photocatalytic activity of ZnO promoted hydrothermally synthesized ZnWO4 nanorods in UV–visible light irradiation." Chemical Engineering Science 212, no. : 115338.
In this study, a two-dimensional (2D) microporous electrospun polyacrylonitrile (PAN) fiber mat was converted into a three-dimensional (3D) mesoporous fiber scaffold via a simple gas foaming technique with a solution of aqueous sodium borohydride (NaBH4). The 3D PAN fiber was coated with ZnO nano-flowers via a facile one-pot hydrothermal process. The 3D PAN/ZnO fibers were rendered modified into hydrophobic or oleophilic through subsequent treatment with dodecyltriethoxysilane (DTEOS). A modified 3D composite was successfully applied for the absorption of oils with a significant sorption capacity for a series of common oils and organic solvents. Interestingly, absorbed oil with in the 3D fiber composite was easily drained by simple mechanical squeezing. The modified hydrophobic 3D PAN/ZnO composite exhibited an excellent oil sorption capacity compared to the 2D PAN/ZnO composite. The oil sorption capacity of the 3D composite was 4 times higher for low density organic solvents and 2 times higher for high density, viscous oils compared to the 2D composite fiber. The effective oil sorption capacity of the 3D composite rendered it as a promising sorbent candidate for oil spill cleanup and oil-water purification.
Hem Prakash Karki; Laxmi Kafle; Han Joo Kim. Modification of 3D polyacrylonitrile composite fiber for potential oil-water mixture separation. Separation and Purification Technology 2019, 229, 115840 .
AMA StyleHem Prakash Karki, Laxmi Kafle, Han Joo Kim. Modification of 3D polyacrylonitrile composite fiber for potential oil-water mixture separation. Separation and Purification Technology. 2019; 229 ():115840.
Chicago/Turabian StyleHem Prakash Karki; Laxmi Kafle; Han Joo Kim. 2019. "Modification of 3D polyacrylonitrile composite fiber for potential oil-water mixture separation." Separation and Purification Technology 229, no. : 115840.
Antimony-doped tin oxide (ATO) nanoparticles with an average size of ~ 6 nm were prepared by co-precipitation and subsequent heat treatment. Graphitic carbon nitride (g-CN)/ATO hybrid nanocomposite was designed by the combination of thermally synthesized g-CN and ATO nanoparticles by ultrasonication. The materials were characterized using N2 adsorption/desorption (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). A mixture of five volatile organic compounds (VOCs, chloroform, benzene, toluene, xylene and styrene) was used to compare the adsorption capacity of the samples. The adsorption capacity of ATO nanoparticles was improved by the addition of g-CN. Experimental data showed that, among the five VOCs, chloroform was the least adsorbed, regardless of the samples. The g-CN/ATO showed nearly three times greater adsorption capacity for the VOC mixture than pure ATO. The unchanged efficiency of VOC adsorption during cyclic use demonstrated the completely reversible adsorption and desorption behavior of the nanocomposite at room conditions. This economically and environmentally friendly material can be a practical solution for outdoor and indoor VOC removal.
Devi Prashad Ojha; Jun Hee Song; Han Joo Kim. Facile synthesis of graphitic carbon-nitride supported antimony-doped tin oxide nanocomposite and its application for the adsorption of volatile organic compounds. Journal of Environmental Sciences 2018, 79, 35 -42.
AMA StyleDevi Prashad Ojha, Jun Hee Song, Han Joo Kim. Facile synthesis of graphitic carbon-nitride supported antimony-doped tin oxide nanocomposite and its application for the adsorption of volatile organic compounds. Journal of Environmental Sciences. 2018; 79 ():35-42.
Chicago/Turabian StyleDevi Prashad Ojha; Jun Hee Song; Han Joo Kim. 2018. "Facile synthesis of graphitic carbon-nitride supported antimony-doped tin oxide nanocomposite and its application for the adsorption of volatile organic compounds." Journal of Environmental Sciences 79, no. : 35-42.
Highly crystalline FeWO4 nanorods (FWO NRs) were prepared using an amine in a hydrothermal reaction. A photocatalyst active to visible light was designed by preparing 5FWO/g-CN heterostructures via in-situ hydrothermal methods. Fabricated heterostructures were analyzed using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), BET measurements, transmission electron microscopy (TEM), X-ray photoelectron microscopy (XPS), and Fourier transform spectroscopy (FTIR). The photocatalytic activity toward the degradation of salicylic acid (SA) was investigated under visible light irradiation. The active species trapping experiments showed that the holes, as well as the electrons, exhibited an obvious influence on the photocatalytic degradation process. Examinations of the mechanism showed that the enhanced photocatalytic activity was mainly ascribed to reduced recombination rate and band gap broadening in a Z-scheme mechanism, which enhance the efficient transfer and the oxidation potential of the holes.
Devi Prashad Ojha; Hem Prakash Karki; Jun Hee Song; Han Joo Kim. Amine-assisted synthesis of FeWO4 nanorodg-C3N4 for enhanced visible light-driven Z-scheme photocatalysis. Composites Part B: Engineering 2018, 160, 277 -284.
AMA StyleDevi Prashad Ojha, Hem Prakash Karki, Jun Hee Song, Han Joo Kim. Amine-assisted synthesis of FeWO4 nanorodg-C3N4 for enhanced visible light-driven Z-scheme photocatalysis. Composites Part B: Engineering. 2018; 160 ():277-284.
Chicago/Turabian StyleDevi Prashad Ojha; Hem Prakash Karki; Jun Hee Song; Han Joo Kim. 2018. "Amine-assisted synthesis of FeWO4 nanorodg-C3N4 for enhanced visible light-driven Z-scheme photocatalysis." Composites Part B: Engineering 160, no. : 277-284.
Highly crystalline FeWO4 nanorods (FWO NRs) prepared by a hydrothermal reaction is combined with g-C3N4 (gCN) nanosheet as an electrode material for the supercapacitor. Fabricated nanocomposites were analysed using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), X-ray photoelectron microscopy (XPS), and Raman Spectroscopy. Pseudocapacitive performance of the FWO/gCN nanocomposite was evaluated by cyclic voltammetry (CV), electrochemical impedance and galvanometric experiments in an alkaline medium. Thus FWO/gCN nanocomposite exhibited a high specific capacitance of 357 Fg-1 at 5 mVs-1 and demonstrated a superior long-term cyclic stability, with the specific capacitance retention of about 80% after 1000 cycles.
Devi Prashad Ojha; Hem Prakash Karki; Jun Hee Song; Han Joo Kim. Decoration of g-C3N4 with hydrothermally synthesized FeWO4 nanorods as the high-performance supercapacitors. Chemical Physics Letters 2018, 712, 83 -88.
AMA StyleDevi Prashad Ojha, Hem Prakash Karki, Jun Hee Song, Han Joo Kim. Decoration of g-C3N4 with hydrothermally synthesized FeWO4 nanorods as the high-performance supercapacitors. Chemical Physics Letters. 2018; 712 ():83-88.
Chicago/Turabian StyleDevi Prashad Ojha; Hem Prakash Karki; Jun Hee Song; Han Joo Kim. 2018. "Decoration of g-C3N4 with hydrothermally synthesized FeWO4 nanorods as the high-performance supercapacitors." Chemical Physics Letters 712, no. : 83-88.
In this study, a simple electrospinning method was employed for the fabrication of a durable and renewable cellulose/polyacrylonitrile (cellulose/PAN) composite nanofiber by alternatively piled one over other as stacking. The stacking layers of cellulose/PAN composite fiber was subjected to the hot roller press at 80 °C to enhance the firm attachment of fibers. The hydrophilic composite fiber was fabricated for oil-in-water mixture separation in harsh conditions of different pH. The fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermal stability was monitored by TGA analysis. The tensile stress and the surface wetting behavior were greatly improved for cellulose/PAN composite fiber. The different oils like n-hexane, diesel oil, and toluene were used to prepare oil-in-water mixture solutions. The hydrophilic composite fiber served as a substrate to ensure the high water permeation flux and high separation efficiency with excellent stability and durability. This work projects an easy cost-effective fabrication method of composite fiber for on-demand oil-in-water separation process having good application in adverse situations with excellent recyclability and the maximum separation efficiency up to 97.31%.
Hem Prakash Karki; Laxmi Kafle; Devi Prashad Ojha; Jun Hee Song; Han Joo Kim. Cellulose/polyacrylonitrile electrospun composite fiber for effective separation of the surfactant-free oil-in-water mixture under a versatile condition. Separation and Purification Technology 2018, 210, 913 -919.
AMA StyleHem Prakash Karki, Laxmi Kafle, Devi Prashad Ojha, Jun Hee Song, Han Joo Kim. Cellulose/polyacrylonitrile electrospun composite fiber for effective separation of the surfactant-free oil-in-water mixture under a versatile condition. Separation and Purification Technology. 2018; 210 ():913-919.
Chicago/Turabian StyleHem Prakash Karki; Laxmi Kafle; Devi Prashad Ojha; Jun Hee Song; Han Joo Kim. 2018. "Cellulose/polyacrylonitrile electrospun composite fiber for effective separation of the surfactant-free oil-in-water mixture under a versatile condition." Separation and Purification Technology 210, no. : 913-919.
The hydrophobic nature of the substances has served as important tools for governing the spatial behaviors of various fibrous substances depending on their affinities to oils or organic liquids. Herein, electrospun two-dimensional (2D) polyacrylonitrile (PAN) fiber mat was converted into three-dimensional (3D) mesh by hydrogen gas foaming technique using aqueous sodium borohydride (NaBH4) solution, which on heating at high temperature under a nitrogen atmosphere produced ultra-light, low density, hydrophobic 3D carbon scaffold with distinct affinities to oil phases. The fibrous materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectra. Specific surface area and porosity of the fiber were analyzed by the Brunauer-Emmett-Teller (BET) technique. The carbon scaffold exhibit dominance as absorbents for selectively separating oils such as diesel, canola oil, xylene, and n-hexane with absorption capacity from 68.71 g g−1 to 131.33 g g−1. More interestingly, the absorbed oils were readily collected by simple mechanical squeezing and the recovered 3D carbon scaffold could be reused for the successive absorptions. This carbon scaffold could be a versatile platform to offer a kind of efficient and selective absorbent material for absorption of oils or organic liquids from the water.
Hem Prakash Karki; Laxmi Kafle; Devi Prasad Ojha; Jun Hee Song; Han Joo Kim. Three-dimensional nanoporous polyacrylonitrile-based carbon scaffold for effective separation of oil from oil/water emulsion. Polymer 2018, 153, 597 -606.
AMA StyleHem Prakash Karki, Laxmi Kafle, Devi Prasad Ojha, Jun Hee Song, Han Joo Kim. Three-dimensional nanoporous polyacrylonitrile-based carbon scaffold for effective separation of oil from oil/water emulsion. Polymer. 2018; 153 ():597-606.
Chicago/Turabian StyleHem Prakash Karki; Laxmi Kafle; Devi Prasad Ojha; Jun Hee Song; Han Joo Kim. 2018. "Three-dimensional nanoporous polyacrylonitrile-based carbon scaffold for effective separation of oil from oil/water emulsion." Polymer 153, no. : 597-606.
In this study, we fabricated an antifouling bilayered fibrous filter media having micro-nonwoven by melt blowing and nano-nonwoven by electrospinning process. Silver nanoparticle-incorporated polyurethane nanofibers were electrospun on the meltblown fiber of polypropylene. Silver nanoparticles were synthesized in situ in the polyurethane electrospun nanofibers through reduction of silver nitrate. The filter media were characterized by field emission scanning electron microscope, transmission electron microscopy, and X-ray diffraction and energy-dispersive X-ray spectroscopy analyses. The composite membrane showed that a thin layer of electrospun nanofibers improved the filtration efficiency without substantial increase in pressure drop. In situ synthesis of Ag NPs imparted the antibacterial and antifouling characteristics to the membrane.
Han Joo Kim; Sang Won Han; Mahesh Kumar Joshi; Cheol Sang Kim. Fabrication and characterization of silver nanoparticle-incorporated bilayer electrospun–melt-blown micro/nanofibrous membrane. International Journal of Polymeric Materials and Polymeric Biomaterials 2017, 66, 514 -520.
AMA StyleHan Joo Kim, Sang Won Han, Mahesh Kumar Joshi, Cheol Sang Kim. Fabrication and characterization of silver nanoparticle-incorporated bilayer electrospun–melt-blown micro/nanofibrous membrane. International Journal of Polymeric Materials and Polymeric Biomaterials. 2017; 66 (10):514-520.
Chicago/Turabian StyleHan Joo Kim; Sang Won Han; Mahesh Kumar Joshi; Cheol Sang Kim. 2017. "Fabrication and characterization of silver nanoparticle-incorporated bilayer electrospun–melt-blown micro/nanofibrous membrane." International Journal of Polymeric Materials and Polymeric Biomaterials 66, no. 10: 514-520.
The aim of the present study is to develop a facile, efficient approach to reinforce nylon 6 (N6) nanofibers with cellulose chains as well as to study the effect that cellulose regeneration has on the physicochemical properties of the composite fibers. Here, a cellulose acetate (CA) solution (17 wt%) was prepared in formic acid and was blended with N6 solution (20%, prepared in formic acid and acetic acid) in various proportions, and the blended solutions were then electrospun to produce hybrid N6/CA nanofibers. Cellulose was regenerated in-situ in the fiber via alkaline saponification of the CA content of the hybrid fiber, leading to cellulose-reinforced N6 (N6/CL) nanofibers. Electron microscopy studies suggest that the fiber diameter and hence pore size gradually decreases as the mass composition of CA increases in the electrospinning solution. Cellulose regeneration showed noticeable change in the polymorphic behavior of N6, as observed in the XRD and IR spectra. The strong interaction of the hydroxyl group of cellulose with amide group of N6, mainly via hydrogen bonding, has a pronounced effect on the polymorphic behavior of N6. The γ-phase was dominant in pristine N6 and N6/CA fibers while α- phase was dominant in the N6/CL fibers. The surface wettability, wicking properties, and the tensile stress were greatly improved for N6/CL fibers compared to the corresponding N6/CA hybrid fibers. Results of DSC/TGA revealed that N6/CL fibers were more thermally stable than pristine N6 and N6/CA nanofibers. Furthermore, regeneration of cellulose chain improved the ability to nucleate bioactive calcium phosphate crystals in a simulated body fluid solution.
Mahesh Kumar Joshi; Arjun Prasad Tiwari; Bikendra Maharjan; Ko Sung Won; Han Joo Kim; Chan Hee Park; Cheol Sang Kim. Cellulose reinforced nylon-6 nanofibrous membrane: Fabrication strategies, physicochemical characterizations, wicking properties and biomimetic mineralization. Carbohydrate Polymers 2016, 147, 104 -113.
AMA StyleMahesh Kumar Joshi, Arjun Prasad Tiwari, Bikendra Maharjan, Ko Sung Won, Han Joo Kim, Chan Hee Park, Cheol Sang Kim. Cellulose reinforced nylon-6 nanofibrous membrane: Fabrication strategies, physicochemical characterizations, wicking properties and biomimetic mineralization. Carbohydrate Polymers. 2016; 147 ():104-113.
Chicago/Turabian StyleMahesh Kumar Joshi; Arjun Prasad Tiwari; Bikendra Maharjan; Ko Sung Won; Han Joo Kim; Chan Hee Park; Cheol Sang Kim. 2016. "Cellulose reinforced nylon-6 nanofibrous membrane: Fabrication strategies, physicochemical characterizations, wicking properties and biomimetic mineralization." Carbohydrate Polymers 147, no. : 104-113.
In this study, a fly ash based composite, Ag-iron oxide/fly ash, was synthesized via a facile one-pot hydrothermal process using fly ash, ferrous chloride, and silver nitrate as precursors. Field emission scanning electron microscopy (FE-SEM), EDX, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), Photoluminescence (PL) and Brunauer-Emmett-Teller (BET) surface area measurement confirmed the formation of composite particle. FA provided a suitable surface for the in-situ deposition of Fe3O4 and Ag NPs during hydrothermal treatment. As a result, the particle size of Fe3O4 and Ag NPs was sufficiently decreased, and the surface area of the NPs as well as, a whole matrix was increased. The antimicrobial activity of the composite was accessed by Escherichia coli inhibition assay. Lead(II) ion adsorption efficiency of the composite was analyzed from a series of batch adsorption experiments (the effects of concentration, contact time, pH and adsorbent dose on the adsorption of Pb(II) ion from aqueous solution). Results indicated that as-synthesized composite has high antibacterial capacity, and the metal ions uptake efficiency compared to fly ash particle. Furthermore, incorporation Fe3O4 NPs onto the fly ash make it easily separable from a reaction system using an external magnet. The composite synthesis protocol is a simple method that utilizes a readily available industrial byproduct to produce a unique composite for environmental remediation.
Mahesh Kumar Joshi; Hem Raj Pant; Nina Liao; Jun Hee Kim; Han Joo Kim; Chan Hee Park; Cheol Sang Kim. In-situ deposition of silver−iron oxide nanoparticles on the surface of fly ash for water purification. Journal of Colloid and Interface Science 2015, 453, 159 -168.
AMA StyleMahesh Kumar Joshi, Hem Raj Pant, Nina Liao, Jun Hee Kim, Han Joo Kim, Chan Hee Park, Cheol Sang Kim. In-situ deposition of silver−iron oxide nanoparticles on the surface of fly ash for water purification. Journal of Colloid and Interface Science. 2015; 453 ():159-168.
Chicago/Turabian StyleMahesh Kumar Joshi; Hem Raj Pant; Nina Liao; Jun Hee Kim; Han Joo Kim; Chan Hee Park; Cheol Sang Kim. 2015. "In-situ deposition of silver−iron oxide nanoparticles on the surface of fly ash for water purification." Journal of Colloid and Interface Science 453, no. : 159-168.
In this study, we investigated the effects of canola oil biodiesel (BD) to improve combustion and exhaust emissions in a common rail direct injection (DI) diesel engine using BD fuel blended with diesel. Experiments were conducted with BD blend amounts of 10%, 20%, and 30% on a volume basis under various engine speeds. As the BD blend ratio increased, the combustion pressure and indicated mean effective pressure (IMEP) decreased slightly at the low engine speed of 1500 rpm, while they increased at the middle engine speed of 2500 rpm. The brake specific fuel consumption (BSFC) increased at all engine speeds while the carbon monoxide (CO) and particulate matter (PM) emissions were considerably reduced. On the other hand, the nitrogen oxide (NOx) emissions only increased slightly. When increasing the BD blend ratio at an engine speed of 2000 rpm with exhaust gas recirculation (EGR) rates of 0%, 10%, 20%, and 30%, the combustion pressure and IMEP tended to decrease. The CO and PM emissions decreased in proportion to the BD blend ratio. Also, the NOx emissions decreased considerably as the EGR rate increased whereas the BD blend ratio only slightly influenced the NOx emissions.
Sam Ki Yoon; Min Soo Kim; Han Joo Kim; Nag Jung Choi. Effects of Canola Oil Biodiesel Fuel Blends on Combustion, Performance, and Emissions Reduction in a Common Rail Diesel Engine. Energies 2014, 7, 8132 -8149.
AMA StyleSam Ki Yoon, Min Soo Kim, Han Joo Kim, Nag Jung Choi. Effects of Canola Oil Biodiesel Fuel Blends on Combustion, Performance, and Emissions Reduction in a Common Rail Diesel Engine. Energies. 2014; 7 (12):8132-8149.
Chicago/Turabian StyleSam Ki Yoon; Min Soo Kim; Han Joo Kim; Nag Jung Choi. 2014. "Effects of Canola Oil Biodiesel Fuel Blends on Combustion, Performance, and Emissions Reduction in a Common Rail Diesel Engine." Energies 7, no. 12: 8132-8149.