Ex) Article Title, Author, Keywords
pISSN 0374-4914
eISSN 2289-0041
pISSN 0374-4914
eISSN 2289-0041
Ex) Article Title, Author, Keywords
Abstract : In this study, we report the experimental observation of the magnetic domain structure and magnetic domain dynamics in Co/Ni multilayer thin films with or without antiferromagnetic IrMn layer, respectively. First, as a result of observing the magnetic domain structure using a magnetic force microscopy, it is found that the magnetic domain size decreases as the Co/Ni layer thickness increases, and that the samples with the IrMn layer have the larger magnetic domain sizes than the samples without the IrMn layer. Also, using a magneto-optical Kerr magnetometer capable of measuring the magnetic viscosity curve, we find that the magnetization reversal phenomenon in all samples is explained by the thermally activated model. Additionally, it is found that the samples with the IrMn layer have the larger activation volumes than the samples without the IrMn layer.
Abstract : We report a 121Sb nuclear magnetic resonance (NMR) study on polycrystalline Ti3Sb in its normal state. Interestingly, the 121Sb spectrum reveals two distinct, well-resolved peaks accompanied by an extremely broad background signal. This suggests a significant inhomogeneity in the local environments surrounding most of the antimony atoms. Through measuring the temperature dependence of the Knight shift, which is equivalent to the intrinsic spin susceptibility, and the spin-lattice relaxation rate (T1-1), which probes low-energy spin dynamics, we conclude that the ground state of Ti3Sb in the normal state is consistent with a non-magnetic normal metal or Fermi liquid. Taking into consideration this Fermi liquid behavior and the relatively high superconducting transition temperature, the extreme chemical inhomogeneity might be a unique feature in Ti3Sb.
Abstract : BiFeO3 (BFO) and 0.67BiFeO3-0.33BaTiO3 (33BT) thin films are deposited using RF magnetron sputtering, and the effects of oxygen partial pressure on the crystal structure, microstructure, leakage current, and ferroelectric properties are investigated. X-ray diffraction pattern analysis reveals that the BFO film grows in a polycrystalline form, while the 33BT film grows in the (111) direction. Microstructural analysis shows that surface roughness increases at higher oxygen partial pressures, and the 33BT film exhibits smaller average grain sizes compared to the BFO film. According to the analysis of the leakage current conduction mechanism, more oxygen vacancies are generated in thin films deposited under low oxygen partial pressure. Additionally, the 33BT thin film exhibits a lower leakage current density compared to BFO, due to the stabilization effect of free carriers trapped by Ti+4 substitution, as well as smaller grain size and lower surface roughness. Ferroelectric hysteresis loop measurements show that the BFO film deposited at low oxygen partial pressure exhibits a typical hysteresis loop, while the film deposited at higher oxygen partial pressure shows a loop affected by leakage current. In contrast, the 33BT film exhibits a typical hysteresis loop regardless of oxygen partial pressure.
Abstract : It is commonly believed that catalysts based on noble metal possess significantly enhanced activity for selective hydrogenation reactions, in contrast to metal oxides that are almost inactive. In this paper, we report Na0.2WO3/Ag2O nanocomposite by a simple preparation of Na0.2WO3 nanorods and the electroless deposition of Ag2O nanoparticles on Na0.2WO3 nanorods. And, Na0.2WO3/Ag2O nanocomposite shows excellent catalytic activity for hydrogenation of 4-nitrophenol compared with Na0.2WO3 nanorods. Also, Na0.2WO3/Ag2O nanocomposites show excellent recycling properties. This work revealed the synergistic catalytic activity of Ag2O nano-particles and Na0.2WO3 nanorods, resulting in enhanced catalytic activity for toxic 4-nitrophenol reduction. This nanocomposite could be a great solution for wastewater treatment.
Abstract : The study analyzes the perceptions of outstanding science students regarding the causes of errors and possible countermeasures in temperature measurement as foundational work to reinforce understanding of error and uncertainty in experiment education. The participants are 14 candidates for the Korean national team in the Junior Science Olympiad selection process, including 6 students officially selected for the team. The observation of temperature measurement tasks and related interviews are conducted with the candidates, while written interviews are conducted with the final team members. The analysis reveals that students failed to distinguish between random errors and systematic errors, often resorting to simply calculating averages to determine the final measurement results. Notably, students don't reach the level of comprehensively understanding the concepts of measurement and error to proactively address the sources of errors. Instead, they remain at the level of merely following prescribed procedures.
Abstract : The purpose of this study is to analyze the inquiry process of science-gifted students using classical methods in relation to Galileo's inclined plane experiment and to assess their perception of classical experimental methods. The gifted students designed and conducted experiments using both classical methods, simulating the 17th-century context, and modern methods, utilizing video analysis techniques. The main research findings are as follows. First, the gifted students designed and conducted experiments using the classical method with time and travel distance as the main variables, employing pendulums, water clocks, constant velocity motion devices, and hourglasses as time measurement tools. Second, despite the presence of error factors due to uncertainty in human sensory perception or the limitations of measurement tools in the classical method, the experimental results are very successful. Third, many gifted students exhibited a positive shift in their perception of classical methods after the activity. Based on the findings of this study, the potential for integrating classical methods with modern methods is discussed.
Abstract : Recent technological advancements in EdTech provide opportunities to easily create environments where various representations can be observed simultaneously in classrooms. Augmented Reality (AR), which can superimpose virtual objects onto real ones, is expected to be suitable for lessons based on multiple representations. The use of Head-Mounted Displays (HMD) is anticipated to contribute to creating more sophisticated and immersive AR environments. This study aims to develop AR-HMD content related to image formation by convex lenses. This AR-HMD content allows users to observe images formed on a screen using real convex lenses and light sources, providing macroscopic representations of real objects. The path of ray diagrams, a symbolic representation overlaid on these images, is adjusted in real-time according to user and object movements. The developed AR-HMD content will be utilized in pre-service teacher education and professional development through future applications and improvements.
Abstract : Augmented reality (AR) scientific educational contents necessitate features that differentiate it from virtual reality (VR) materials. However, most AR physics education contents being developed and implemented do not significantly differ from VR contents, other than using the real world as a background to enhance realism or as markers to increase interactivity. This research focuses on extracting detailed suggestions for AR physics education content production, primarily considering the perspectives of prospective elementary teachers, the end-users of such content. For this purpose, preservice elementary teachers are asked to suggest improvements for existing elementary physical science experiments using AR and their reasons for these improvements. The study analyze the subjects, types, rationales, and strengths and weaknesses of the 101 cases of AR experiments suggested by the preservice teachers. Based on their insights, the paper proposes implications for the development of AR content in physics education.
Abstract : The purpose of this study is to analyze research trends in measuring science teachers’ digital literacy and to examine the main theoretical frameworks for digital literacy. To achieve this purpose, a bibliometric analysis and topic modeling are conducted on 86 articles collected from the Web of Science, and the major theoretical frameworks are analyzed. The results indicate a recent rapid increase in research on measuring science teachers’ digital literacy, with main research topics encompassing TPACK(Technological Pedagogical Content Knowledge)-based teaching and learning, digital literacy assessment, technology integration and self-efficacy, and the theoretical framework of technology integration. The theoretical frameworks of digital literacy are categorized into three main groups: ‘TPACK-based,’ ‘practical TPACK,’ and ‘digital literacy and competency.’ Additionally, implications for measuring the digital literacy of science (physics) teachers are discussed.
Abstract : In the field of the electromagnetic interference shielding, tremendous research reports mainly have focused on the development of an advanced shielding architecture by modifying its structure and/or optimizing physical properties. It is well-known that shielding materials exhibit frequency-dependent physical properties (i.e., electrical conductivity, permittivity, and permeability, etc.). Therefore, shielding characteristics analysis should reflect this variability. In this study, we present the frequency-dependent shielding characteristics of layered structures based on a π-conjugated conducting polymer. The theoretical and experimental evaluation shows that the shielding efficiency of the multi-layered structure reached up to 29.6 dB and ∼28 dB, respectively, which are also confirmed by complex scattering parameter measurement. In addition, our analysis based on transfer matrix method clearly shows frequency-dependent shielding characteristics.
Abstract : The electromagnets used in the 4th Generation electron Storage Ring (4GSR) require a higher field gradient than the conventional magnets facilitated in a machine. However, the magnetic field at the pole-tip saturates at the level of 1.3 T, resulting in the dilution of the operational efficiency. Therefore, a higher magnetic field gradient is only feasible by reducing the diameter of the magnet. However, as the diameter of the magnet decreases, the shape of the pole determines the higher-order term strongly, so it is essential to take account into the design of the magnet. In this presentation, we present an optimization strategy of the pole shape for the occasion of magnetic saturation using a 2D solver and Pymoo optimization algorithms using the Poisson Superfish code.
Abstract : The governing equation of primordial gravitational waves in de Sitter space takes the form of a harmonic oscillator with a time-dependent frequency. The Ermakov-Lewis invariant of this time-dependent harmonic oscillator is obtained using the mode solutions of the primordial gravitational wave and an auxiliary equation, which is dual to the mode equations, in de Sitter space. Additionally, the dual symmetry of the mode functions of the primordial gravitational wave is briefly mentioned by employing the invariance of the Schwarzian derivative.
Youngchun Jo, Haeyong Kang, Hyunkyung Lee, Jinho Jeon, Hyeonseop Lee, Kanghyun Kim
New Phys.: Sae Mulli 2024; 74(1): 25-34
https://doi.org/10.3938/NPSM.74.25
Sangwoo Ha
New Phys.: Sae Mulli 2023; 73(9): 734-749
https://doi.org/10.3938/NPSM.73.734
Min-Seong Kim, Nam-Hwa Kang
New Phys.: Sae Mulli 2023; 73(3): 256-265
https://doi.org/10.3938/NPSM.73.256
pISSN 0374-4914
