npsm 새물리 New Physics : Sae Mulli

pISSN 0374-4914 eISSN 2289-0041
Qrcode
  • Research Paper 2024-03-29

    Current-Voltage Characteristics of Ferroelectric SrBi2Ta2O9 Thin Films

    Sang Bo Bae, Hwan Min Kim, Ill Won Kim

    Abstract : We grow SrBi2Ta2O9 (SBT) thin films, one of the actively studied lead-free ferroelectric materials, with different Bi/Sr compositions using pulsed laser deposition (PLD) method and measured their leakage current characteristics according to electric field and temperature changes. Schottky barrier height, trap center level, and activation energy were studied. The current-voltage characteristics of the SBT thin film with a Bi/Sr composition ratio of 2.8 showed resistive leakage current characteristics in which the leakage current strongly depended on the delay time in the applied electric field of 80 kV/cm or less. Below 150 C, the SBT (Bi/Sr = 2.8) thin film showed linear current-voltage characteristics consistent with the Schottky emission conduction model at an applied electric field of 80 to 200 kV/cm, and the Schottky barrier height and trap center level were 1.02 eV and 0.83 eV, respectively. The activation energies of the SBT thin films of 2.8 Bi/Sr ratio showed 0.72 eV and 0.58 eV below 150 C, 3 V, and 10 and 100 sec delay time. This phenomenon is because Bi ions acted as charge carriers in the form of acceptors.

    Show More  
  • Research Paper 2024-03-29

    A Comparison of the South Korean and German Secondary School Curricula in Quantum Physics

    Andreas Woitzik, Taegyoung Lee, Nam-Hwa Kang

    Abstract : With increasing attention drawn towards quantum physics and its applications in teaching and research, the question of which concepts of quantum theory can be taught at different educational levels becomes more and more important. To this end, we compare the curricula of Germany (Baden-Württemberg) and South Korea. In Germany, more students take physics courses that contain quantum physics than in South Korea. We find that many quantum physics learning objectives are commonly covered, but with recent increases in quantum physics content in both countries’ curricula their approaches increasingly differ. The South Korean curriculum focuses more on technology and classical quantum concepts, whereas the German curriculum is more concerned with epistemological questions. Through an investigation of the textbooks of both regions, we found differences in laboratory activities and approaches to deal with some concepts. The findings demonstrate some consensus on the content to be taught in high school physics while the differences in the curriculum and textbooks of the two regions provide insight into pedagogical approaches and future research.

    Show More  
  • Research Paper 2024-02-29

    Magnetic and Structural Variations Depending on the Annealing Temperature of Co Films on Al2O3(0001)

    Kangjin Park, Yeongjun Son, Sehwan Song et al.

    Abstract : This study deposited a cobalt (Co) film on the Al2O3(0001) substrate by a flash evaporation method to examine the structural and magnetic property variations depending on the various post-annealing temperatures. Co-film formed islands during annealing due to the surface energy mismatch between the metallic film and the insulating substrate. As a result, the post-annealed Co particles formed an ellipsoid shape with improved crystallinity as temperature increased. Structural analysis confirmed that the Co particles grew in the Co(111)-oriented FCC structure. Interestingly, there are different annealing-temperature-dependent characteristics of magnetic properties depending on the magnetic field direction due to the competing nature between the crystalline and shape anisotropy of the aggregated Co particles.

    Show More  
  • Research Paper 2024-02-29

    Detection of Water Droplets in Oil-Filled Dielectric Tubes by Microwave Near Field Imaging

    Hyeri Song, Hanju Lee

    Abstract : Detecting impurities within fluids is a crucial technology in various industries such as chemical plants, equipment manufacturing, and automotive systems. In this study, we conducted research on detecting water droplets in dielectric tubes filled with oil using microwave near-field imaging. We visualized the distribution of microwave near-fields in oil-filled dielectric tubes containing water droplets located at different positions. The measurement results showed that the microwave near-field distribution of oil-filled dielectric tubes changed depending on the position of the water droplets, and the change was maximized when the microwave electric field is parallel to the length direction of the tubes. From the experimental results, we showed that the near-field imaging technology can be applied for detecting impurities inside fluid-filled tubes, showcasing its potential usefulness in impurity detection.

    Show More  
  • Research Paper 2024-01-31

    Properties of Si-AlN Core-Shell Microcrystals by Al-Based Nanostructures

    Suhyun Mun, Seonwoo Park, Kyoung Hwa Kim et al.

    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.

    Show More  

Current Issue

    March 2024 | Vol. 74 No. 3
  • Research Paper 2024-03-29

    Current-Voltage Characteristics of Ferroelectric SrBi2Ta2O9 Thin Films

    Sang Bo Bae, Hwan Min Kim, Ill Won Kim

    Abstract : We grow SrBi2Ta2O9 (SBT) thin films, one of the actively studied lead-free ferroelectric materials, with different Bi/Sr compositions using pulsed laser deposition (PLD) method and measured their leakage current characteristics according to electric field and temperature changes. Schottky barrier height, trap center level, and activation energy were studied. The current-voltage characteristics of the SBT thin film with a Bi/Sr composition ratio of 2.8 showed resistive leakage current characteristics in which the leakage current strongly depended on the delay time in the applied electric field of 80 kV/cm or less. Below 150 C, the SBT (Bi/Sr = 2.8) thin film showed linear current-voltage characteristics consistent with the Schottky emission conduction model at an applied electric field of 80 to 200 kV/cm, and the Schottky barrier height and trap center level were 1.02 eV and 0.83 eV, respectively. The activation energies of the SBT thin films of 2.8 Bi/Sr ratio showed 0.72 eV and 0.58 eV below 150 C, 3 V, and 10 and 100 sec delay time. This phenomenon is because Bi ions acted as charge carriers in the form of acceptors.

    Show More  
  • Research Paper 2024-03-29

    Performance Enhancement of Broadband MoS2/LaVO3 Photodetector by Employing Thickness-controlled LaVO3

    Da Hyeon Kim, Han Noh, Si Duck Oh et al.

    Abstract : A broadband photodetector (PD) was successfully fabricated by combining LaVO3 with a chemical vapor deposition-MoS2. We systematically measured the performance of the PD by varying the LaVO3 thickness. All devices had the highest photocurrent/dark current (DC) ratio at 0 V, meaning “self-powered”. The performance characteristics of the PD depended on t. In particular, the highest detectivity of the device was 2.7 × 1012 cmHz1/2W−1 at t = 200 nm due to a trade-off between photoresponsivity and DC. Additionally, the 290 μs rise/580 μs decay times showed better performance than previously reported MoS2-based devices.

    Show More  
  • Research Paper 2024-03-29

    Wavelength-Resolved Neutron Imaging Technique for Metal Material Analysis

    Junyoung Son, Seung Wook Lee

    Abstract : Wavelength-Resolved Neutron Imaging is an emerging technology in the field of radiographic imaging, offering not only absorption imaging but also a broad range of crystallographic information. For Wavelength-Resolved Neutron Imaging, it is crucial to predict and apply a consistent coherent elastic scattering cross-section that varies with the neutron wavelength and the crystallographic form of the specimen. In this study, pure iron (Fe 99.9%) samples were used to apply Wavelength-Resolved Neutron Imaging to the analysis of uniaxial compressive deformation. This allowed for the analysis of signal changes due to alterations in crystal structure and the calculation of average internal strain. Additionally, by conducting the experiment at a small pulsed neutron facility, the feasibility of acquiring crystallographic data at low flux was confirmed.

    Show More  
  • Research Paper 2024-03-29

    A Comparison of the South Korean and German Secondary School Curricula in Quantum Physics

    Andreas Woitzik, Taegyoung Lee, Nam-Hwa Kang

    Abstract : With increasing attention drawn towards quantum physics and its applications in teaching and research, the question of which concepts of quantum theory can be taught at different educational levels becomes more and more important. To this end, we compare the curricula of Germany (Baden-Württemberg) and South Korea. In Germany, more students take physics courses that contain quantum physics than in South Korea. We find that many quantum physics learning objectives are commonly covered, but with recent increases in quantum physics content in both countries’ curricula their approaches increasingly differ. The South Korean curriculum focuses more on technology and classical quantum concepts, whereas the German curriculum is more concerned with epistemological questions. Through an investigation of the textbooks of both regions, we found differences in laboratory activities and approaches to deal with some concepts. The findings demonstrate some consensus on the content to be taught in high school physics while the differences in the curriculum and textbooks of the two regions provide insight into pedagogical approaches and future research.

    Show More  
  • Research Paper 2024-03-29

    Preservice Physics Teachers' Conceptual Understanding and Its Degree of Certainty on Special Relativity Theory

    Sungmin Im

    Abstract : In this study, we investigated the conceptual understanding and its degree of certainty on special relativity theory among preservice physics teachers. By applying the Relativity Concept Inventory, we collected responses from 51 preservice physics teachers majoring in physics at college of education. Based on the response data, we analyzed the distribution of conceptual understanding and its degree of certainty on special relativity theory and the respondents’ personal variables. As a result of analysis, preservice physics teachers have difficulty understanding the concepts of relativity of simultaneity, speed composition, and causality, and misconceptions are found in time dilation and the relativity of simultaneity. There is no difference between genders in conceptual understanding, but men’s degree of certainty is relatively higher. The level of prior learning about relativity theory is related to conceptual understanding but has nothing to do with the degree of certainty. There is a positive correlation between conceptual understanding and the degree of certainty, and this is clearly evident in the group that most recently learned relativity.

    Show More  
  • Research Paper 2024-03-29

    Proposal of Quantitative Analysis Method for Non-linear Electric Circuits Composed of Light Bulbs

    Seongsoo Jeon

    Abstract : The purpose of this study is to present a method for quantitatively analyzing nonlinear electric circuits based on graphical methods. Ohm’s law cannot be applied to an electrical circuit consisting of a tungsten filament bulb with nonlinear resistance. However, because there is no proper method to quantitatively analyze nonlinear electric circuits, the room temperature resistance of the light bulb has been used, or the rated resistance of the light bulb calculated using Ohm’s law for the rated voltage and rated current of the light bulb has been used. In this study, nonlinear electric circuits were quantitatively analyzed using the graphical resistance of the light bulb obtained graphically through the current-voltage characteristic curve of the light bulb, and compared with the results of methods based on Ohm’s law. The electric circuit was limited to two light bulbs and consisted of a series connection of the light bulbs and a parallel connection of the light bulbs, and cases where the room temperature resistance of the two light bulbs were the same and cases where they were different were distinguished. The results of the quantitative analysis of the electric circuit were compared in percentage error between the calculated values of voltage and current and the measured values obtained through experiment. The percent error of the method that applied the graphical resistance of the light bulb was found to be less than 2.8%, which is a very small value compared to the method that applied the room temperature resistance of the light bulb and the rated resistance of the light bulb.

    Show More  
  • Research Paper 2024-03-29

    University Students' Understanding of the Behavior of Light and Their Reasoning to the Particle-like Nature of Light in the Photoelectric Effect

    Yong Wook Cheong, Jinwoong Song

    Abstract : University students’ understanding of the photoelectric effect is investigated through semi-structured interviews and a written questionnaire. For the purpose of our study, we distinguish between two kinds of reasoning: the construction of a photon model of light to explain the experimental results of the photoelectric effect and one interpreting the nature of light in the context of the photoelectric effect. It was found that many students only had an energy description for the interaction between light and an electron and did not further elaborate on the physical processes. Students also struggled to explain the experimental results using the concept of the photon. We also investigated students’ reasoning in linking the photoelectric effect and the particle-like nature of light. Students in the study believed that the effect refuted the classical model, yet, did not sufficiently link the effect to the particle-like nature of light. Furthermore, they did not well describe the particle-like properties of light revealed in the photoelectric effect. Their particle conceptions were not clearly related to the photon’s properties. Finally, we suggest the implications of this study on the future teaching of the photoelectric effect and how the work relates to previous studies in this area.

    Show More  
  • Research Paper 2024-03-29

    Output Characteristics of the 1064 nm Nd:YVO4 Regenerative Amplifier

    Hyuk Jeong, Dohwan Kwon, Gyu Ug Kim

    Abstract : We calculated the output power of the seed pulse amplified by the 1064 nm Nd:YVO4 regenerative amplifier using ASLD program. In the absence of seed pulse, it was calculated that the maximum power of the cavity-dumped oscillator is 70.6 W and the radius of the pumping beam is 1.3 mm, when the distance between the focusing lens of the 888 nm pumping laser and the gain medium Nd:YVO4 is 88 mm. And it was calculated that the 1064 nm pulse energy increased linearly as the number of round trips of the seed pulse increased. Based on these results, we constructed the optical system of the regenerative amplifier. We measured the output power, beam quality, and intensity distribution of the 1064 nm laser. The average power and pulse energy of the amplified seed pulse was 24 W and 240 μJ, respectively. The beam quality was measured to be Mx2 = 1.199, My2 = 1.172, and circularity was 93%.

    Show More  
  • Research Paper 2024-03-29

    A Pilot Study on the Correlation Between Electrons and Antioxidant Phenomenon Using an Electron Producing Apparatus (EPA)

    Dong-Hyun Lee, Chang-Woo Seon

    Abstract : The aim of this study was to evaluate the correlation between electrons injected through an electron producing apparatus (EPA) and redox reactions of human body. The onset of the disease is directly related to changes in acid-base metabolism in the blood. When the balance of acid-base metabolism in the blood is broken due to various factors, inflammation occurs due to metabolic disorders in the cells and tissues that make up each organ. Based on this theory, it was necessary to develop a apparatus to control acid-base balance and verify its effectiveness. This study was based on the pilot study which means for one subject. The redox reaction of human body was measured by pH/ORP meters after sampling in the urine and blood of the subject. EPA generates minus electron that works for reduction which means neutralizing hydrogen ions of oxidized metabolites. It is expected that lots of study can be perfomed about the relation between redox reaction of human body and disease status.

    Show More  
  • Research Paper 2024-03-29

    Reanalysis of the Data from LUX-ZEPLIN and PandaX-4T Experiments using WimPyDD

    Chang Seob Ro, Gaurav Tomar, Jong-Chul Park

    Abstract : We reanalyze the data from dark-matter direct detection (DD) experiments utilizing a Python-based analysis program, WimPyDD. Among various on-going DD experiments, we take the data from LUX-ZEPLIN (LZ) and PandaX-4T experiments which use liquid xenon (LXe) as a target material to search for signals by weakly interaction massive particles (WIMPs). Our analysis has been done by implementing the experimental conditions and measured data of each experiment in WimPyDD. As a result, we can obtain limits on the scattering cross section assuming WIMPs spin-independently interact with the nucleus of LXe, which are compared with the analysis results from experimental collaborations. Furthermore, we obtain bounds on effective mass scale M as a function of the WIMP mass for spin-independently interacting models.

    Show More  

All Newest Articles

Current Issue

March 2024
Vol.74 No.3

pISSN 0374-4914
eISSN 2289-0041

submit an article

pISSN 0374-4914
eISSN 2289-0041