Ex) Article Title, Author, Keywords
Abstract : Recently, various materials have been introduced to develop a functional device. Specifically, graphene is transparent, flexible, and has high electrical conductivity. A porous silicon surface with numerous nanopores demonstrates a high density charge trapping property. This study investigates the hysteresis characteristics of porous silicon using a graphene/porous silicon heterostructure. Metal assisted chemical etching was used to develop porous silicon on a silicon substrate. The top electrode was fabricated by transferring an extended area of graphene prepared by chemical vapor deposition. Also, the bottom electrode was fabricated under the silicon substrate using a silver paste. The current voltage (I−V) characteristics of various porous silicon devices with controlled porosity were measured. The hysteresis property was observed in the current voltage curve of the device with high porosity. However, hysteresis characteristics were not observed in devices with low porosity.
Abstract : Low-dimensional materials have attracted considerable attraction due to their high potential in applications in optoelectronic devices given their unique physical properties. In this study, a thin-film photodetector was developed using graphene with a high electrical conductivity and perovskite quantum dots with a charge-trapping property. The transparent and flexible graphene was transferred onto a silicon oxide. Metal electrodes were fabricated at both ends, and perovskite quantum dots were coated between them. The I−V curve characteristics were observed by measuring the current while changing voltage in dark and light conditions. The photocurrent was confirmed after observing the higher current in the light condition than in the dark condition. In the case of irradiating laser pulse, the current as a function of time was also measured. When laser was applied, the current rapidly increased, and when the laser was turned off, the current decreased slowly by more than several thousands of seconds.
Abstract : Using the QCD sum rule including the instanton contributions from two quarks, we discuss scalar meson a0(980) as a tetraquark state where two tetraquark states, with one state consisting of the spin-0 diquark and anti-diquark and the other state comprising spin-1 diquark and anti-diquark, are mixed. We construct the QCD sum rule including the contributions from the operator product expansion up to the energy dimension 10 of O(αs) and from the instanton. As a result of QCD sum rule analysis, we show that the mass of a0(980) fitted from the QCD sum rule becomes more stable and has a value closer to experimental quantity when the contribution from the instanton is included.
Abstract : The differential cross sections of 240 MeV 6Li elastic scattering on 24Mg, 28Si, 40Ca, 58Ni, 90Zr, and 116Sn targets are systematically analyzed using the eikonal model based on the Coulomb trajectories of colliding nuclei. The model calculations successfully reproduced the structure of the elastic scattering cross sections, and provided fairly good description of the experimental measurements. The oscillatory patterns shown in the experimental elastic angular distributions are well explained in terms of the strong interference between the near- and far-side scattering amplitudes. The reaction cross sections obtained from the analysis of 6Li elastic scattering on various targets from 24Mg to 116Sn are found to have linear dependence on the (AP1/3+AT1/3)2. The partial reaction cross sections increased linearly up to some peak values and thereafter decreased rapidly to zero.
Abstract : In this study, we will examine the Raman and Compton scattering theories to explain a mechanism of the blue light emitted by a UV germicidal lamp, whose average wavelength is between λ ≈ 260 nm and λ ≈ 360 nm. A germicidal lamp emits ultraviolet C light (UV-C), which has a wavelength between 100 nm and 280 nm. Man can typically see visible light with a wavelength between 380 nm and 780 nm, but cannot see UV light from a germicidal lamp. However, we can observe the blue light that emanates from a germicidal lamp (wavelength for blue from 465 nm to 482 nm and violet from 380 nm to 450 nm). There are various reasons why we can measure the blue light coming from a UV germicidal lamp. Because a germicidal UV lamp emits blue light, this study will focus on the scattering, particularly the Raman and Compton. We will make a suggestion for exploiting the scattering-induced redshifts for a tiny neutral particle around the atoms.
Abstract : This study analyzed the topic and level of questions generated by pre-service physics teachers in university flipped learning classes. The topics and levels of 103 questions generated by pre-service physics teachers in a flipped learning class were analyzed. The analysis of question topics showed that 26.2% of concept category questions and 26.2% of knowing category questions were found. The application, equation, experiment, and limit category questions accounted for 15.5%, 13.6%, 11.7%, and 6.8%, respectively. In the analysis of question levels, the most common questions were the medium-level ones (43.7%), followed by the minimum-\,(28.2%), high-\,(18.4%), and low-level (8.7%) questions. In the analysis of question topics, various categories of question topics were presented from the middle of the semester rather than at the beginning. These results suggest that pre-service physics teachers were using various learning strategies to understand the learning content through repetitive question-generating activities in flipped learning classes. Therefore, flipped learning classes had a positive effect on the pre-service physics teachers in terms of using various question topics to understand the learning content. In addition, the highest number of questions observed at the medium level indicated that pre-service physics teachers had difficulties in understanding the learning content. Therefore, instructional design is required to link the questions generated by pre-service physics teachers in flipped learning classes with face-to-face lectures.
Abstract : This study was analyzed the types of class participation included in the lesson plans of pre-service physics teachers. The elements of class participation were analyzed by dividing them into ‘depth of knowledge’, ‘higher-order thinking’, ‘connectedness to the world beyond the classroom’, ‘substantive conversation’, and ‘social support for student achievement’. The analysis results showed that `depth of knowledge' was presented the most among the types of class participation in lesson plans. In addition, analysis of variance (ANOVA) was conducted to determine whether the types of class participation differed depending on the instruction model. As a result of ANOVA, `depth of knowledge', `connectedness to the world beyond the classroom', and `social support for student achievement' showed significant differences according to the instruction model. Examination of the relationship among class participation types showed positive correlations between `connectedness to the world beyond the classroom' and `social support for student achievement' and between `substantive conversation' and `social support for student achievement'. The results of this study suggest that opportunities for pre-service physics teachers to understand class participation should be expanded in the teacher education curriculum.
Abstract : We studied the effect of voltage drop and phase delay caused by passive elements, such as resistors, inductors, and capacitances, after the application of an external driving voltage to an RLC electric circuit. A two-dimensional isotropic harmonic oscillator of mechanics was analyzed to investigate the effect of delay on the magnitude and phase of the system voltage compared with the external driving force. The phase difference showed dependence on the driving frequency. The angle ψ between the major axis of the ellipse and the x-axis in the two-dimensional XY plane graph was obtained. We investigated the Lissajar patterns in the oscilloscope. In addition, it can be divided into linear, circular, and elliptical polarizations based on the frequency, phase, and amplitude from the viewpoint of light polarization. The Jones matrix was investigated by the corresponding harmonic oscillator analysis of mechanics and Jones vector in the polarization of light.
Abstract : Herein, we proved the equivalence of the formulas for the magnetic force and torque between magnetic dipoles derived from the Lorentz force, the gradient of the magnetic potential, and the derivative of the mutual inductance. In a current flowing system, such as two circular loops with diﬀerent diameters, we calculated the magnetic force and torque to demonstrate the equivalence of the formulas using the Lorentz force, magnetic potential energy, and mutual inductance.
Abstract : Quantum Information Software Kit (Qiskit) is an open-source SDK for working with quantum computers of IBM Quantum Experience, and it is available for everyone who is interested in programming real quantum computers. Open Quantum Assembly Language (OpenQASM) is an intermediate representation of quantum instructions. Jupyter notebook is a web-based interactive computational environment for the creation of notebook documents for Python language. In this paper, we introduce four compact versions of Jupyter notebook environment to help students start programming with IBM Quantum Experience using Qiskit and OpenQASM.
Abstract : The three-dimensional off-lattice AB protein model is one of the most successful simplified protein models that incorporates the essential physics of protein folding. In this study, more than one million three-dimensional conformations of the Trp-cage protein are effectively searched in the three-dimensional off-lattice AB protein model using a powerful global optimization method known as conformational space annealing. Among the more than one million three-dimensional conformations of the Trp-cage protein, we focus on ten thousand low-energy conformations. The energy landscape and the optimized three-dimensional structures of the Trp-cage protein are investigated by analyzing the ten thousand low-energy conformations of the Trp-cage protein.
Abstract : With the advancement in technology, forgers further improve their methods to create more accurate forgeries. Although various techniques have been used to detect forged banknotes, the use of microwave spectrum in detecting forged banknotes is a relatively new research area. In this study, we investigated the application of microwave energy in detecting forgeries on banknotes. The proposed method was based on the thermoelastic optical indicator microscopy technique, which visualized the distribution of microwave near-fields. The Korean banknotes of 1000 won, 5000 won, and 10,000 won, and their corresponding scanned samples were selected, and the distribution of microwave near-field was measured. Our results showed a strong distribution of the microwave magnetic near-field on the hologram at 12 GHz for 5000 won and 10,000 won, and the field distribution of the corresponding scans was different. On the other hand, the microwave near-field distribution of the 1000 won and its scan showed a similar distribution.
Abstract : Fresnel lens, the lens used in a lighthouse, is a large-diameter lens used for transmitting the light beam to a distant location. It is a compressed form of a refractive lens with a special optical system to reduce the volume. Factors, such as focal length, optical material, the number of grooves (the number of areas), and inclination of the groove, affect the optical performance of this lens. To design a Fresnel lens for large-size lighthouses, we applied the paraxial optical theory to construct the basic layout of the optical system. Given the use of an analytical method for mechanical structural injection molding, design variables were determined to satisfy each constraint by setting the optical element for each sag as a part of an independent donut-shaped ring lens. In addition, the optical system was designed to optimize the collimation beam for the light source point. The lighting characteristics of the optical system designed in this way satisfy the divergence angle within ±4° with respect to the maximum luminous intensity.
Abstract : The quality inspection of edible eggs is a technology that examines the size, color, and freshness of eggshells and is essential before the distribution of edible eggs. Existing edible-egg quality inspection technologies include the inspection by broken eggs method, specific gravity method, and fluoroscopy method. In this study, we report a novel method for assessing the quality of quail eggs by imaging and analysis of microwave near-field distribution. After inducing various types of artificial defective conditions of quail eggs, the distribution of the microwave near field was imaged, and changes in the distribution of the near field due to defective conditions were compared and analyzed. Through measurement results, we confirmed that the defective state of edible eggs can be detected non-destructively and non-invasively through microwave near-field imaging.
Woo Tae Hong, Hyun Kyoung Yang
New Phys.: Sae Mulli 2021; 71(3): 236-241
YeonJung PARK, Joonghoe DHO*
New Phys.: Sae Mulli 2021; 71(5): 450-456
Jongwon PARK, Insun LEE*
New Phys.: Sae Mulli 2021; 71(5): 476-489