Ex) Article Title, Author, Keywords
Abstract : Ti3O5 exhibits a metal-insulator transition (MIT) accompanied by a structural change from β- phase to λ-phase at 514 K. During the transition, Ti3O5 demonstrates significant resistance changes and high thermal energy storage characteristics. To harness the beneficial characteristics of Ti3O5, it is essential to develop a growth method that yields homogeneous samples and to control the phase transition temperature. In this study, we successfully synthesized high-quality β-Ti3O5 and λ-AlxTi3−xO5 polycrystalline samples using an arc melting method. Furthermore, the structural and physical properties of β-Ti3O5 and λ-AlxTi3−xO5 were investigated as a function of the Al doping ratio. Our results suggest that the arc melting method provides an effective way to synthesize high-quality Ti3O5 and control the transition temperature of the MIT.
Abstract : To fabricate large-area graphene transistors, the transfer of chemical vapor-deposited graphene onto preferred substrates and the patterning of drain/source electrodes are necessary. However, these transfer and deposition processes commonly employ polymers such as poly(methyl methacrylate) and photoresists, which can leave residual polymers and adsorbed molecules on the channel, thus affecting the electrical properties of the devices. In this study, we investigated the effects of heat treatment on the device characteristics related to the polymer residues and adsorbates on graphene surface by analyzing the transfer curves. Our findings demonstrate that proper vacuum annealing can enhance the device’s performance and reduce contact resistance. Moreover, we propose an advanced procedure that incorporates thermal annealing under vacuum after each step of polymer removal. This method is particularly beneficial for enhancing the contact and surface properties of channels in general fabrication processes involving polymers.
Abstract : Hexagonal Si-AlN core-shell microcrystals were grown by the mixed-source hydride vapor phase method. In particular, it was found that the hexagonal Si-AlN core-shell microcrystals were grown by the role of the Al-based nanostructure. Since hexagonal Si has a quasi-direct bandgap energy and AlN also has a hexagonal wurtzite structure, it can open up new opportunities for power semiconductors or optoelectronic devices. In this paper, the hexagonal Si-AlN core-shell microcrystals grown were characterized using scanning electron microscopy (FE-SEM), EDS and HRTEM, and the growth mechanism is presented. Therefore, the hexagonal Si-AlN core-shell microcrystal is expected to be an example of a new method in the field of semiconductor growth.
Abstract : Optoelectronic properties of a phototransistor made from solution-processed amorphous InGaZn oxide (a-IGZO) were investigated. This wide bandgap metal oxide semiconductor is known for its optical transparency, yet it exhibits visible light absorption attributed to sub-gap states resulting from oxygen vacancies. The study found that depositing a thin layer of aluminum oxide (AlOx) on the transistor channel led to an increase of photocurrent in the visible spectrum. Additionally, surface treatment of the a-IGZO thin film with UV ozone reduced persistent photoconductivity at 450 nm. Analysis of the absorption coefficient and optical band gap indicated that the results were associated with changes in the oxygen vacancy states within the a-IGZO thin film. The ability to control photocurrent and persistent photoconductivity through the deposition of aluminum (Al) and UV ozone treatment opens up exciting possibilities for applications in photosensors and neuromorphic systems.
Abstract : The Rare isotope Accelerator complex for ON-line experiments (RAON) utilizes the ISOL method to produce rare isotopes. In this process, protons can be accelerated and directed to collide with a uranium-238 target, leading to the extraction of rare isotopes from the resulting fragments. This research involves the prediction of proton-induced uranium fission nuclear reactions through calculations based on the Langevin method. To evaluate the predictive accuracy, we employ a well-established multimodal empirical formula for comparison. A discrepancy in the MDFF become evident in high-proton beam fission, emphasizing the need for model improvements. By visualizing the potential energy surface of the compound nucleus, the significance of shell effects is recognized. This study serves as motivation to identify and implement improvements in our approach, with the goal of enhancing the accuracy of fission predictions in the future.
Abstract : Preclinical positron emission tomography (PET) detectors use very small-sized scintillation pixels to achieve high resolution. Since the scintillation pixels of this size are very small compared to the size of the photosensor pixels, the scintillation pixels located at the edges overlap in the image. To solve this problem, a light guide was applied to reduce the occurrence of overlapping by differentiating the distribution of light. In this study, a light guide made of the same material as the scintillation pixel was used to develop a detector that exhibits a much improved degree of separation compared to conventional light guides. Flood images were acquired to evaluate the degree of image separation between the edge scintillation pixels of the detector using the existing light guide and the newly developed detector. As a result of calculating the degree of separation between the two edges of the scintillation pixel image in the acquired flood imgae, the scintillator light guide showed a better degree of separation than the conventional light guide. In addition, as a result of calculating the spatial resolution of the scintillation pixel image near the edge and center, the result of using the scintillator light guide showed better spatial resolution. The superior spatial resolution of each scintillation pixel image indicates that the degree of separation between adjacent scintillation pixel images is more excellent. If the detector developed in this study is used for preclinical PET, it will be possible to improve image quality by improving overall system spatial resolution.
Abstract : In this research, we perform numerical simulations of 20Na+208Pb reactions to study heavy ion collisions with an isotope that will be produced at RAON accelerator. We use two different models, Daejeon Boltzmann-Uheling-Ulenbeck (DJBUU) transport model and Sindong Quantum Molecular Dynamics (SQMD) transport model. We compare fragments identified at the end of simulation time. We find that there are noticeable differences in the biggest fragment(BF) produced between DJBUU and SQMD. To describe heavy ion collisions more precisely, We discuss initial conditions in transport model simulation, such as distance between projectile and target nuclei, and improvement plans of each models.
Abstract : Diagnostic radiation shielding facilities provide radiation protection, comprising various components such as radiation shields and patient-viewing windows. Lead, the primary material used in these structures, may pose health risks to humans due to oxidation, cracking, and aging. This study employed Monte Carlo Simulation to appraise the shielding performance by altering the composition of lead sheets and lead glass. We conducted simulations for peak tube voltages of 80 and 120 kVp. As the lead oxide content in the lead sheet increases, the shielding performance decreases by up to 10%. Additionally, as the crack’s size increases, the leakage dose increases by approximately 7%. Moreover, the reduction in the lead oxide proportion of the lead glass resulted in diminished shielding performance. The findings regarding radiation attenuation rates in this study are considered valuable data for future assessments of radiation shielding facilities’ aging.
Abstract : This study aimed to analyze the characteristics of pre-service physics teachers’ adaptive practices. For this purpose, we analyzed teaching and learning process plans, video recordings, field observation notes of 10 classes conducted by 7 pre-service teachers during their teaching practicum and interviews. We found a total of 24 adaptive practice cases. The main research results were as follows. First, the most frequent adaptive practices were ‘coordination of learning activities’, ‘omission of activities or materials’, ‘adjustment of concept level and scope’, and ‘addition of materials, examples, demonstrations, etc.’. Second, ‘coordination of learning activities’ and ‘omission of activities or materials’ are types that do not appear often among science teachers, but are often seen among pre-service teachers due to the lack of opportunities for pre-service teachers to practice classes. Third, pre-service teachers could hardly use adaptive practices commonly used by science teachers, such as ‘adding demonstrations’, ‘helping with numeracy/literacy’, ‘encouraging learner participation’, and ‘using analogies or metaphors’. Based on the results, implications for pre-service teacher education were discussed.
Abstract : This study aimed to extract the characteristics of domestic research related to HMD through literature research and to derive implications for the use of HMD in physics education. A total of 161 papers were retrieved through a keyword search of the database, and 120 papers were selected for analysis based on abstract review. As a result of the study, HMD-related papers could be classified into three types: technical element related to HMD, effect and influence using HMD, and development and application of contents utilization with HMD. The technical elements related to HMD involve physical improvements, such as optical design, and software improvements, such as increased processing speed. The Effect and influence using HMD include positive effects, such as improved long-term memory based on a sense of presence, and negative effects, such as motion sickness. In terms of the development and application of contents utilization with HMD, we found information regarding the transition to the virtual world and the effects of developing and applying content for education and training.
Abstract : In temperature measurement, the instrument error is larger than the human error. In this study, we aimed to analyze the features of alcohol thermometers and probe-type thermometers commonly utilized in schools. The research results are as follows. First, there was a significant difference between the values indicated by several thermometers under the same conditions. Additionally the difference in readings between the two thermometers generally did not change significantly with measurement target’s temperature. Second, it requires a relatively long time for the scale to stabilize. When comparing the time constant, the short probe thermometer takes the shortest time to stabilize, followed by the long probe thermometer and then the alcohol thermometer. Third, when measuring the temperature of a liquid, if the depth of the thermometer submerged in water is above a certain limit, the difference in the scale value depending on the depth is relatively small.
Abstract : In this study, we would like to introduce a 3D printing technology on the nanoscale that utilizes nanophotonics and a modified atomic force microscope (AFM) for the assembly of quantum dots. Quantum dots are semiconductor nanostructures with zero-dimensional crystal structures at the nanometer scale, exhibiting unique optical properties due to quantum confinement effects. These quantum dots, with sizes on the order of a few nanometers, have garnered significant attention in various optical fields. By printing these quantum dots onto 2D materials or other substrates in desired shapes, we open up possibilities for controlling their energy structures and utilizing them in various ways. In this technology, we inject a quantum dot solution into the nanophotonic tip and use an AFM to precisely deposit the quantum dots at desired locations and shapes. In the initial stages of this technology, we achieve this by ejecting the quantum dot solution onto the surface through the holes in the nanophotonic tip. Simultaneously, as we retract the nanophotonic tip vertically, the liquid containing quantum dots evaporates, leading to the formation of bundled quantum dot nanowires. This innovative approach holds promise for a wide range of applications where precise manipulation of quantum dots at the nanoscale is crucial.
Abstract : A sensor that can measure the concentration of harmful chemicals in water using changes in surface resistance was fabricated using a metal oxide nanoparticle film, and the changes in sensor performance due to surface treatment processes were investigated. The influence of the surface residue of the organic binder used for film printing was focused on, and the changes in the properties of the film and sensor were observed. To remove the residual binder, a cleaning process was additionally introduced to the existing sintering process, and the changes in the properties of the ITO:CB film were observed according to the cleaning time, and the surface treatment time was optimized. It was confirmed that the sensor response improved as the cleaning time increased, and the optimal surface treatment conditions were determined to ensure good sensor operation.
Abstract : In order to use heavy metals in water for detection, a film using ITO (Indium Tin Oxide) nanoparticles was produced, and a chemoresistive sensor was produced using it to confirm the metal ion detection performance. The ITO film was produced by mixing nanoparticles and organic binders to produce paste and printing it on a PET substrate. The sensor was manufactured by forming Ag electrodes on both ends of the manufactured film, and the detection characteristics of the sensor were confirmed using five (Mn, Zn, Se, Sn, Ni) metal ion aqueous solutions. It was verified that the sensor resistance linearly increased according to the increase in the concentration of the metal ion, and that the concentration and resistance change linearly. The sensor’s performance was evaluated using the sensor’s response (ΔR), limit of detection, response time, linearity, error, and detection range.
Abstract : A method was studied to remove the zero-order term in holography, utilizing the subtraction of two on-axis holograms and the adjustment of reference wave polarization. A hologram is created by the interference of reference light and object light, containing 0th-order diffraction light and information about real and virtual images. By subtracting two holograms, both formed by the interference of two reference waves with different linear polarization directions but with the same polarization object wave, a zero-order cancellation hologram can be created. This technique was validated through both computer simulations and experiments, confirming that the 0th-order diffracted light can be effectively eliminated.
Aekyung Shin, Donggeul Hyun, Jeongwoo Park
New Phys.: Sae Mulli 2023; 73(1): 37-43
Geon Park, Inseo Kim, Hojung Sun, Yongjei Lee, Kimoon Lee, JungYup Yang
New Phys.: Sae Mulli 2023; 73(1): 23-28
Sangwoo Ha, Hunkoog Jho
New Phys.: Sae Mulli 2022; 72(4): 319-328