Papers by Author: Young Soo Kang

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Authors: Chang Woo Kim, Young Hwan Kim, Don Keun Lee, In Chul Jeong, Hae Woong Kwon, Young Soo Kang
Abstract: We report the core/shell type as the interesting one of the various techniques to prepare exchange-coupled permanent magnet. In this study, the exchange-coupled Nd2Fe14B/α-Fe was prepared by high energy ball mill process and chemical reduction. Nd15Fe77B8 powder prepared by high energy ball mill process was coated with α-Fe nanoparticle by chemical reduction. α-Fe nanoparticle on the ball milled Nd15Fe77B8 was synthesized by chemical reduction with borohydride as a reducing agent in aqueous solution. After annealing, Nd2Fe14B/α-Fe forming core/shell shape has exchange-coupling effect and was identified by using XRD, FE-SEM, VSM, TMA and EDX.
Authors: Hyo Sim Kang, Sun Wha Oh, Young Soo Kang
Abstract: We prepared various pyrazoline derivatives which possess dimethylamino-, ethoxy-, isopropyl-phenyl ring at the 5-position of pyrazoline. The nanoparticles of pyrazoline derivative ranging from tens to hundreds of nanometers by the reprecipitation method have been successfully prepared and their optical size-dependent properties have been investigated with UV-vis, fluorescence spectroscopy, DLS (Dynamic Light Scattering) and SEM. The size-dependent optical properties of pyrazoline organic nanoparticles have been observed in the order of dimethylamino- > ethoxy- > isopropyl- in electro-donating characters.
Authors: Xiao Li Zhang, Young Soo Kang
Abstract: The monodispersed zinc oxide nanowires with lateral dimensions as thin as 20 nm and lengths up to 2 μm have been synthesized in a simple organic solution by using hydrothermal method. Particularly, these zinc oxide nanostructures has been prepared into single-crystalline prisms or belts with uniform diameters along the entire length. The structure and characteristic of the as-obtained ZnO nanostructures were confirmed by XRD, TEM, HRTEM, and EDX. UV measurements and photoluminescence had been used to characterize the optical properties and confirm the crystal perfection of these ZnO nanomaterials.
Authors: Song Lee, Byung Hyun Ahn, Sun Wha Oh, Young Soo Kang
Abstract: In this work, low density polyethylene (LDPE) was grafted with trifluoroacetic acid allyl ester using γ-ray irradiation from a Cobalt-60 source at different adsorbed doses. It was found that the grafting degree increases with the absorbed doses. The highest grafting degree was obtained at 100 kGy of absorbed dose and with 30 wt% of trifluoroacetic acid allyl ester. The grafting was identified with fourier transform infrared (FT-IR) using a calibration curve reported in literature. Thermal properties of the functional polymers were studied by thermogravimetric analysis (TGA) and the surface morphology was investigated by scanning electron microscope (SEM).
Authors: Young Hwan Kim, Beong Gi Jo, Jee Hean Jeong, Young Soo Kang
Abstract: A room temperature route for doping silica particles with Cu nanoparticles to achieve hybrid structures is introduced. First, silica nanoparticles were synthesized according to the well-known Stöber method by hydrolysis and condensation of TEOS in a mixture of ethanol with water, using ammonia as catalyst to initiate the reaction. These SiO2 nanoaprticles were dried at 100 oC. We measured the size of these nanoparticles with transmission electron microscopy (TEM). Second, Cu-SiO2 nanoparticles were synthesized by reaction with CuCl2 and SiO2 nanoparticles in presence of catalyst at room temperature for 12 hrs. Results show silica nanoparticles of about 70 nm size with regularly deposited Cu nanoparticles. Cu-SiO2 nanoparticles were investigated with TEM images, energy dispersive X-ray analysis (EDX) spectrum and so on.
Authors: Hyun Gil Cha, Young Hwan Kim, Don Keun Lee, In Chul Jeong, Hae Woong Kwon, Young Soo Kang
Abstract: The magnetic α-Fe nanoparticles were carried out using two-preparation methods that include solution phase metal salt reduction and organometallic precursor decomposition. Under the different reaction conditions such as precursor and reaction time, the magnetic properties of α-Fe nanoparticles were studied. The size of nanoparticle was confirmed by transmission electron microscope (TEM) images. The magnetic properties were characterized with saturation magnetization(Ms) from hysteresis loop by vibrating sample magnetometer (VSM). The crystallinity and structure of α-Fe nanoparticles was investigated by X-ray diffraction (XRD).
Authors: Chang Woo Kim, Young Soo Kang
Abstract: Nd-Fe-B nanoparticles was prepared by coprecipitation method in aqueous solution. The parameters for the composition are the concentration of borohydride solution and the pH of the solution containing metal ion. The B and Nd contents were found to vary with pH and borohydride concentration. The crystal structure of the synthesized nanoparticles was identified with X-ray powder diffraction (XRD). The size and shape of nanoparticles were confirmed by transmission electron microscope (TEM). The magnetization curves of nanoparticles and nanocomposite were characterized with vibrating sample magnetometer (VSM). Energy dispersive X-ray spectrometer (EDS) was used to characterize composition of Nd-Fe-B nanoparticles.
Authors: Jong Hwa Baek, Seog Young Yoon, Young Soo Kang, Hong Chae Park
Abstract: Spherical nano-sized SiO2 particles have been synthesized from sodium silicate by emulsion method. The influence of emulsifier content and mixing time on the morphology and particle size distribution of the resulting materials was investigated. The characteristics of the obtained SiO2 particles were examined by means of XRD, SEM, TEM, and PSA. The monodispersed shperical SiO2 with the average particle size 20 nm was obtained at a emulsifer content of 3vol% and mixing time of 60 min using ultrasonic disruptor. After calcining at 1200oC for 2 hrs, the amorphous SiO2 transformed wholly to the crystalline cristobalite. As increase in emulsifier content from 1 to 3 vol% did not nearly influence on the morphology of SiO2 particle but slightly changed the particle size distribution. The average particle size of SiO2 decreased significantly from 100 nm to 20 nm with increasing the mixing time.
Authors: H.Y. Nam, S.K. Kwon, Young Soo Kang, Jai Sung Lee
Abstract: Sintering process of powder injection molded (PIMed) Fe-50wt%Ni nanoalloyed powder was investigated in association with microstructure development and residual impurity effect. Compared to conventional powder metallurgical (PM) processed Fe-Ni nanoalloy powder, the PIM compact showed a homogeneous and uniform densification behavior. This is owing to more homogeneous particle distribution in the PIM resulting from preparation of feedstock which was fabricated by mixing of nano powder with thermoplastic binder. Residual impurities originating from the binder material did not have any apparent influences on sintering behavior. Conclusively, Fe-50wt%Ni nanoalloy powder is effectively applicable to the PIM parts.
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