npsm 새물리 New Physics : Sae Mulli

pISSN 0374-4914 eISSN 2289-0041
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  • Research Paper 2024-10-31

    Research on Neuromorphic Synaptic Devices Using Mesh-type Platinum Floating gate

    Soyeon Jeong,  Jaemin Kim,  Hyeongjin Chae et al.

    Abstract : Recently, researches on the various types of neuromorphic synaptic devices are attracting attention. In this paper, a synaptic device was fabricated and its characteristics were analyzed using a mesh-type platinum floating gate that mimics nanoparticles. Compared with single floating gates, mesh-type floating gates have a wider memory window and excellent electrical characteristics with improved operation speed and retention. Appropriate thickness conditions were set by checking the EOT (equivalent oxide thickness) and breakdown voltage of the tunnel oxide and control oxide using capacitance-voltage curves and a current-voltage curve. Excellent program and erase operation, synaptic weight, repeatability, reproducibility and memory window width were confirmed using the capacitance-voltage curves. It was compared whether the same performance was achieved even if part of the floating gate was damaged, suggesting the possibility of a synaptic device.

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  • Research Paper 2024-10-31

    Optimizing Bath Fitting in Dynamical Mean-Field Theory Using Machine Learning

    Taeung Kim, Ara Go*

    Abstract : Hamiltonian-based impurity solvers for dynamical mean-field theory (DMFT) approximate a continuous hybridization function with a finite set of effective bath orbitals to keep computational costs manageable. This process involves minimizing a cost function that quantifies the difference between the hybridization function of the continuous bath and that of a finite number of bath orbitals. However, as the number of effective bath orbitals increases, minimizing a multi-dimensional cost function becomes increasingly complex, and the computational expense of optimizing bath parameters escalates. To address these challenges, we employ a machine learning approach using supervised learning to replace computationally intensive tasks. We test various features and labels to identify efficient machine-learning models capable of bypassing the time-consuming bath fitting procedure.

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  • Research Paper 2024-09-30

    Analysis of Pre-service Elementary School Teachers' Preconceptions of Light Shapes from Light Bulbs Through a Small Hole

    Jihoon Kang*, Pyoungkil Yoo

    Abstract : This study investigated pre-service elementary school teachers' preconceptions regarding the shape of light from the bulbs passing through a small hole by varying the shape of the hole (circular or triangular) and the type of light source (point, linear, or composite). The analysis revealed that the majority of participants, regardless of the number or shape of light sources, responded that the light passing through a circular hole would form a single circular shape on the screen, while the light passing through a triangular hole would form a single triangular shape on the screen. Additionally, 74 participants (71.2%) consistently responded with misconceptions across all the questions. They believed that the shape of light projected onto the screen was determined by the hole shape in the mask, or that the light spread out in a circular manner after passing through the small hole. Furthermore, some participants believed that as the number or size of bulbs increased, the lit area on the screen would also become larger. The findings could be used as fundamental data for developing educational courses and programs at teacher training universities (colleges) to correct the pre-service elementary school teachers' misconceptions regarding the rectilinear propagation of light.

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  • Research Paper 2024-09-30

    Spatial Resolution of Chirped Spectral Domain Interferometry according to the Spectral Resolution of the Spectrometer

    Hyun Sung Kim, Seung Seok Lee, Eun Seo Choi*

    Abstract : Unlike normal interference signals, chirped interference signals cannot be used to obtain the position of a reflector using the Fourier transform. Instead, convolution can extract information about the center wavenumber of the chirped interference signal, which can then be converted into specific position information. The positions and full-width at half maximum (FWHM) of the characteristic peaks resulting from the convolution are interpreted as the position and spatial resolution of the reflector. In this study, the chirped interference signals were acquired by varying the wavelength resolution of the spectrometer from 0.05 to 1.0 nm and the convolution of these signals was analyzed. As the wavelength resolution of the spectrometer was varied, the position of the characteristic peak remained similar, but the FHWM increased proportionally. The spectral resolution of the spectrometer did not have a significant effect on determining the position of the reflector, but higher spectral resolution resulted in better spatial resolution.

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  • Review Paper 2024-08-30

    Leveraging Generative AI in Physics Education: Addressing Hallucination Issues in Large Language Models

    Hunkoog Jho*

    Abstract : In recent years, generative AI technology, especially large language models (LLMs), has garnered significant attention for its potential to transform education. This paper provides an overview of generative AI's development and examines its impact on education, focusing on the issue of `hallucinations' in LLMs. It explores the causes and proposes solutions such as finetuning, reasoning, iterative querying, and Retrieval-Augmented Generation (RAG). These methods aim to enhance the accuracy and reliability of AI responses. Examples of AI applications in education include real-time student query responses, personalized learning pathways, and assessment feedback. While these technologies promise to improve educational quality, they also raise concerns about biases and data privacy. This paper discusses strategies to effectively utilize generative AI in education, aiming to improve quality while minimizing negative impacts.

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Current Issue

    October 2024 | Vol. 74 No. 10
  • Research Paper 2024-10-31

    A Study of Flash Memory Type Synaptic Single Devices Manufactured Using Gold Particles

    Jaemin Kim,   Soyeon Jeong,   Taehwan Koo et al.

    Abstract : In this study, a neuromorphic device was developed by utilizing gold nanoparticles to emulate synaptic signal processing. To minimize leakage current, a high-k dielectric used as the insulating layer, and gold nano particles were deposited on the floating gate for electron storage and erasure. The device was fabricated with a vertical structure composed of Pt/Cr/HfO2>/Au/HfO2>/SiO2>/Si substrate. By adjusting the flat band voltage, the optimal operating voltage was determined to avoid damaging the device. Appropriate voltages were applied to the control gate to conduct capacitance-voltage measurements, and the memory window of the gold particles was evaluated. By modulating the applied voltage and duration, the trapping of electrons was controlled to modulate synaptic strength through cycles of potentiation and depression. This research demonstrates the potential of gold nano particles to represent multiple synaptic weights stages, reflecting the electrical characteristics of multi-stage neuromorphic devices.

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  • Research Paper 2024-10-31

    Luminescent Properties and LED Application of Y2GeMoO8:Eu3+ Phosphors

    Woo Tae Hong, Hyun Kyoung Yang*

    Abstract : A series of Eu3+- doped Y2GeMoO8 (YGMO:Eu3+) red-emitting phosphors were synthesized via solid-state reaction methods. Under 395 nm excitation, the YGMO:Eu3+ phosphor exhibits dominant emission at 614 nm owing to the 5D07F2 transition of Eu3+ ions. The luminescence intensity was maximized when the Eu3+ concentration was 50 mol% of Y3+ ions, which was caused by the energy transfer between the nearest-neighbor Eu3+ ions. Red-emitting light-emitting diodes (LEDs) were fabricated by encapsulating YGMO:Eu3+ phosphors on UV LEDs to determine the performance of the YGMO:Eu3+ phosphor. The CIE (International Commission on Illumination) 1931 coordinates of the fabricated LEDs were (0.453, 0.312). These results indicate that the YGMO:Eu3+ phosphor can be used as a red phosphor in phosphor-converted warm white LEDs.

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  • Research Paper 2024-10-31

    Research on Neuromorphic Synaptic Devices Using Mesh-type Platinum Floating gate

    Soyeon Jeong,  Jaemin Kim,  Hyeongjin Chae et al.

    Abstract : Recently, researches on the various types of neuromorphic synaptic devices are attracting attention. In this paper, a synaptic device was fabricated and its characteristics were analyzed using a mesh-type platinum floating gate that mimics nanoparticles. Compared with single floating gates, mesh-type floating gates have a wider memory window and excellent electrical characteristics with improved operation speed and retention. Appropriate thickness conditions were set by checking the EOT (equivalent oxide thickness) and breakdown voltage of the tunnel oxide and control oxide using capacitance-voltage curves and a current-voltage curve. Excellent program and erase operation, synaptic weight, repeatability, reproducibility and memory window width were confirmed using the capacitance-voltage curves. It was compared whether the same performance was achieved even if part of the floating gate was damaged, suggesting the possibility of a synaptic device.

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  • Research Paper 2024-10-31

    Room Temperature Single-Photon Source of Colloidal Quantum Dots

    Eunjeong Lee,  Heejin Choi,  Seonyeong Kim et al.

    Abstract : Materials for single photon sources keep attracting attention owing to the recent development of quantum information technologies such as computing, communications, cryptography, sensing, and metrology. However, commercializing such materials is still facing difficulties for solid reproduction and operations at room temperature because most single photon sources acquire sufficient photon generation efficiencies only at cryogenic temperatures. Here, we review colloidal quantum dots synthesized at low cost and showing high fluorescence efficiencies at room temperature. We discuss the physical and optical characteristics of chemically synthesized colloidal quantum dots, and then relevant single photon measurements and single photon devices.

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  • Research Paper 2024-10-31

    Limitations of Flow Model Due to Geometric Differences Between Gravity and Electric Potential Difference

    Juhyung Shin, Won Kun Oh*

    Abstract : This study was to find out the effects and limitations of learning electric circuits of middle school students through the well-known water flow model. We asked to the students how well the correspondence between each element was, how the elements and properties of each model were understood, and whether the understanding of the electric circuit could be appropriately expressed in pictures using the water flow model. The results showed that less-achieving students in science did not properly relate each object and target, or between attributes. Even high-achieving students were confused about interelated objects and targets. In particular, they failed to express the water height difference, and thus did not represent the role of gravitational potential enough. But students were not properly aware of the difference between the potential difference by height and that of battery independent on height or position, and were unable to fully understand the relationship between the two models.

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  • Research Paper 2024-10-31

    The Characteristics of Energy Concepts in Preservice Physics Teachers: Focusing on Ontological Categories

    Hyojoon Kim, Sangwoo Ha*

    Abstract : Energy is a fundamental concept in physics, but its abstract nature often challenges students' comprehension. Understanding how students perceive energy within different ontological categories is crucial for assessing their conceptual development. In this study, a descriptive questionnaire was developed and analyzed from an ontological perspective to investigate the level of understanding of the concept of energy among preservice physics teachers. The questionnaire consisted of items related to energy concepts in everyday life, mechanics, thermodynamics, electricity, and waves. The research findings indicate that the ontological categorization of energy varies depending on the problem situation. Specifically, there was a matter-based ontological understanding in the order of mechanics, waves, thermodynamics, and electricity. Additionally, through inductive analysis, researchers identified patterns, such as `energy possession,' `movement of energy,' `energy transform,' `work-energy principle,' and `conservation of energy.' Finally, we discussed the implications of these research findings for energy teaching and learning.

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  • Research Paper 2024-10-31

    Analysis of Pre-service Physics Teachers’ Understanding of Curl and Stokes Theorem and Conservative Force in the Mechanics

    Sangyou Park, Youngrae Ji*

    Abstract : This study aims to obtain implications by analyzing the understanding of the conservative force, curl, and Stokes theorem of pre-service physics teachers. To this end, 27 pre-service teachers were surveyed, and some were interviewed in depth. According to study results, Of the 27 pre-service physics teachers, 5(19%) wrote the curl operator correctly, and only 3(11%) explained the meaning of curl about rotation. In addition, there was a tendency to determine curl by adding up the vectors in the area in a two-dimensional vector field, and the percentage of correct answers was low in the questions about calculating line·area integrals according to the path. In addition, the conservative and non-conservative forces could not be explained scientifically, and the correct answers were low in questions about determining conservative forces using the curl operation and calculus calculation questions to find the work done by conservative forces, and the vector field showing rotation was explained as a conservative force field. Based on the results of this study, some suggestions for teaching and learning curl and preservation power were presented in this study.

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  • Research Paper 2024-10-31

    Analysis of Sentence Structure and Verbs Diversity of High School Physics Achievement Standards in the 7th – 2022 Revised Curriculum

    Jee Hyun Koh, Kwanghee Jo*

    Abstract : In this study, we attempted to explore changes and characteristics according to the curriculum by analyzing achievement standards covering high school physics content for five curricula from the 7th curriculum to the recent 2022 revised one. The subjects of the study were a total of 17 physics related subjects and 360 achievement standard sentences. According to research results, the achievement standards for high school physics can be expressed in about 100 short sentences on average, and the ratio of short and compound sentence types has changed several times due to the characteristics of the curriculum. The 2009 revised curriculum had the largest number of substantive achievement standards, while the 2007 and 2015 revised curriculum generally had a small number. Through analysis using the number of substantive achievement standards and variety of verbs, it was found that revising the curriculum tends to be different from the pattern of description in the previous curriculum especially. In addition, the educational implications of these results were discussed.

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  • Research Paper 2024-10-31

    Optimizing Bath Fitting in Dynamical Mean-Field Theory Using Machine Learning

    Taeung Kim, Ara Go*

    Abstract : Hamiltonian-based impurity solvers for dynamical mean-field theory (DMFT) approximate a continuous hybridization function with a finite set of effective bath orbitals to keep computational costs manageable. This process involves minimizing a cost function that quantifies the difference between the hybridization function of the continuous bath and that of a finite number of bath orbitals. However, as the number of effective bath orbitals increases, minimizing a multi-dimensional cost function becomes increasingly complex, and the computational expense of optimizing bath parameters escalates. To address these challenges, we employ a machine learning approach using supervised learning to replace computationally intensive tasks. We test various features and labels to identify efficient machine-learning models capable of bypassing the time-consuming bath fitting procedure.

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  • Review Paper 2024-10-31

    Current Status and Prospects of Quantum Search Algorithm: Grover’s Algorithm

    Joonho Bae*

    Abstract : With the recent advancements in quantum computing, research on Grover's algorithm has gained significant momentum. Grover's algorithm is well-known for providing a quadratic speedup over classical algorithms in solving unstructured search problems, making it particularly useful for tasks such as large-scale database searches, cryptanalysis, and optimization problems. This review offers a brief explanation of the fundamental principles of Grover's algorithm and examines the latest trends in applying it to various problems. It highlights key achievements in experimental implementation of Grover's algorithm alongside the development of quantum hardware, including implementations on superconducting and ion trap-based quantum computers. Lastly, it summarizes recent research achievements in the cryptographic applications of Grover’s algorithm, as well as in constraint satisfaction problems and approximate matching, providing an outlook on future research directions and potential applications.

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  • Research Paper 2024-10-31

    Visible Light Sensor Based on Downsized Fiber Bragg Grating Coated with Elastic Polymer including Carbon Nanotubes

    Jeong Min Seo, Jong-Ju Moon, Tae-Jung Ahn*

    Abstract : A visible light sensor based on a fiber Bragg grating (FBG) coated with a carbon nanotube (CNT) containing an ultraviolet-curable elastic polymer was proposed. The fundamental principle is the unique propensity of the CNT coated on the FBG surface to bend toward the direction of incident visible light. This curvature subsequently transmitted a force to the FBG. This force influenced the grating period of the FBG, leading to a shift in its center wavelength. Employing FBGs with diameters of 80 μm and 125 μm, we empirically substantiated this principle and ascertained the responsive nature of the FBG sensor coated with CNT and elastomer to visible light. In essence, the 80 μm FBG manifested a shift magnitude nearly double that of the 125 μm FBG. We confirmed the potential of the CNT-coated FBG light sensor as an effective tool for detecting intensities in the visible light spectrum.

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  • Research Paper 2024-10-31

    Optical Characteristics of LED Flat Lighting System According to the Scattering Pattern Processing Conditions of the Light Guide Plate

    So Hee Park*

    Abstract : In order to improve the optical efficiency of a lighting system, a design process using optical characteristics is important to control light more effectively. In this study, to analyze the optical characteristics of the LED flat lighting system according to the processing conditions of the LGP, a v-groove pattern with a width and depth of 0.5 mm was created at the bottom of the LGP with a thickness of 3 mm, and the angles at the vertex and the oblique plane were 53.14°, respectively, was designed to be 63.43°. And we designed the pattern in the form of a diagonal line from the edge of the LGP toward the center. Then, 10 parameters were applied to increase the distance of the scattering pattern by 1 mm, and computer simulation was performed using ray-tracing technique. As a result, when the pattern distance was 1 mm, the illuminance value was 69 lx, while when the pattern distance was 10 mm, it was 112 lx, showing an increase of about 62.3%. As a result of analyzing the optical characteristics specified by region for the center, it was found that when the pattern distance was 10 mm, the minimum value was 80 lx and the maximum value was 163 lx, resulting in a uniformity of 49%. On the other hand, when the pattern distance was 1 mm, the minimum value was 20 lx and the maximum value was 239 lx, resulting in a uniformity of 8%. As a result of these, it was found that when the distance between patterns is reduced, the amount of light increases in the central part, leading to a sharp decline in uniformity.

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Current Issue

October 2024
Vol.74 No.10

pISSN 0374-4914
eISSN 2289-0041

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pISSN 0374-4914
eISSN 2289-0041