Journal of the Korean Physical Society最新文献

This study investigates the structural, electronic, thermodynamic, optical, and thermoelectric properties of the CsTaCl₆ compound using first-principles calculations within the GGA–SOC–U approximation. Electronic band structure analysis indicates an indirect band gap with a value of 3.044 eV, confirming its semiconducting nature, with the valence band maximum primarily composed of Cl-3p orbitals and the conduction band minimum dominated by Ta-5d orbitals. Thermodynamic properties such as volume, Debye temperature, Grüneisen parameter, thermal expansion coefficient, and heat capacities (C_V, C_P) were analyzed as functions of temperature and pressure, revealing typical thermal expansion, softening of lattice vibrations at high temperatures, and stiffening under pressure. Optical properties, including dielectric function, optical conductivity, refractive index, reflectivity, electron energy loss, and absorption coefficient, demonstrate significant optical anisotropy and strong absorption in the visible and UV ranges. Finally, thermoelectric calculations show that CsTaCl₆ is a p-type semiconductor with a positive Seebeck coefficient. The electrical conductivity normalized by relaxation time (σ/τ) increases with temperature, while the electronic part of thermal conductivity normalized by relaxation time (κ_e/τ) also increases. A promising figure of merit (ZT) of nearly 0.8 is achieved at intermediate-to-high temperatures, suggesting CsTaCl₆ as a viable candidate for optoelectronic and thermoelectric applications.

Robust respiratory motion management is crucial in radiotherapy to consider tumor movement throughout the breathing cycle. The widely used gating techniques exhibit limitations such as compromised targeting accuracy and prolonged treatment times. In this study, we developed and evaluated a laser-distance-sensor-based respiratory-training prototype designed to operate seamlessly in a standard gating environment. This study aimed to improve breathing regularity in radiotherapy patients using a new audio-guided respiratory-training approach that utilizes real breath sounds and a highly accurate laser displacement sensor. The system comprised two modules: a laser-based respiratory-monitoring component and an audio-guiding component. The accuracy and reproducibility of the laser module were tested using Vernier calipers and a motion phantom programmed with various sinusoidal and patient-like respiratory patterns. Measurements were obtained across a wide range of amplitudes (2.5–7.5 mm), cycle lengths (1.0–5.0 s), and environmental setups (different angles, lighting conditions, and surface reflectivity). Subsequently, volunteer tests were conducted to assess the clinical feasibility of the audio-guided training by comparing the breathing stability before and after training. Across all tested distances (65–135 mm), the laser sensor showed an average deviation of  ± 0.04 mm from the reference, with standard deviations consistently below 0.03 mm. In motion phantom studies, the measured amplitudes and cycle lengths closely matched the input values, achieving correlation coefficients of ≥ 0.99 even under irregular respiratory patterns. The system performance remained robust to angle deviations (± 15°), low lighting, and surface reflectivity changes. In volunteer tests, the standard deviation of breathing cycles decreased substantially after training (from 0.82 to 0.26 s on average), indicating enhanced breathing regularity and user control. The cost-effective, laser-based respiratory-training system demonstrated high measurement accuracy, stable performance, and clinically relevant improvements in breathing consistency, indicating its potential for integration with laser gating setups, particularly in shell-based radiotherapy treatments.

We investigate the (DD^*) and (Dbar{D}^*) momentum correlation functions in high-energy collisions related to the properties of (T_{cc}(3875)^+) and (chi _{c1}(3872)) exotic hadrons. The two-particle momentum correlation functions can be computed from the interaction between two particles. The one pion exchange interaction model, which is mainly considered as the interaction between two hadrons, is valid for long ranges ((>1) fm). Based on experimental data, we constructed Gaussian potential and Yukawa potential as long-range interaction models. Meanwhile, a short-range interaction between two mesons is constructed from the interquark interaction in the exotic hadron state described in the constituent quark model. We compare the (DD^*) and (Dbar{D}^*) correlation functions computed for these short- and long-range interactions when (T_{cc}(3875)^+) and (chi _{c1}(3872)) are close to the compact diquark–antidiquark configuration and the meson–meson molecular configuration, respectively. As a result, correlations were greater than 1 with long-range interactions and less than 1 with short-range interactions.

The effect of in-situ O₂ plasma treatment on the properties of D-CVD-grown Al₂O₃ layers was investigated. The Al₂O₃ layers were prepared with a high deposition rate, and their surface roughness, density, stoichiometry, and water vapor permeation barrier properties were evaluated before and after the plasma treatment. The results showed that the O₂ plasma treatment significantly reduced the surface roughness and density of the Al₂O₃ layer, while also curing the pores and defects present on its surface. The treatment led to the migration of Al and oxygen adatoms, resulting in a change in the atomic concentration ratio of Al to O and the formation of a strong bonding structure in the Al₂O₃ layer. Furthermore, the water vapor transmission rate (WVTR) of the O₂ plasma-treated Al₂O₃ layer remained low and stable over a prolonged exposure time of 2500 h, demonstrating its enhanced water vapor barrier performance. In contrast, the WVTR of the non-treated Al₂O₃ layer increased significantly after 100 h of exposure. These findings highlight the effectiveness of in-situ O₂ plasma treatment in improving the surface properties and water vapor permeation barrier of D-CVD-grown Al₂O₃ layers, making them promising candidates for various applications requiring high barrier properties.

This study explores the unsteady MHD stagnant point flow of a Casson trihybrid nanofluid comprising gold, silver, and aluminum oxide nanoparticles suspended in the blood of a rotating sphere, with special emphasis on entropy generation analysis aimed at minimizing useful energy losses and enhancing thermal performance. The research incorporates the impacts of quadratic convection, ohmic heating, nonlinear thermal radiation, Darcy–Forchheimer drag, and viscous dissipation. To facilitate numerical analysis, the governing time-dependent nonlinear PDEs are reduced to ordinary differential equations via similarity transformations, which are subsequently tackled using a shooting approach integrated with the fourth-order Runge–Kutta method. The results are validated through comparison with established benchmark solutions, demonstrating excellent agreement and confirming the accuracy of the proposed model. A detailed parametric study examines the influence of physical parameters on velocity components in both streamwise and rotational directions, temperature profiles, entropy generation, the Bejan number, surface shear stress, and heat transfer rate. It is observed that increasing the unsteady parameter from 0.7 to 0.9 enhances the friction factor in the (x^{ * })-direction from 3.335 to 3.370 (approximately 1.05%), in the (z^{ * })-direction from 1.308 to 1.361 (approximately 4.1%), and the Nusselt number from 2.97 to 3.72 (approximately 25%), indicating improved momentum and thermal boundary layer performance. Moreover, entropy generation increases with the Brinkman number, while the Bejan number decreases, reflecting greater heat irreversibility. Rotation cases notably improve heat transfer and change flow behavior compared to non-rotating conditions. These findings underscore their relevance in biomedical applications, such as hyperthermia-based cancer treatment, targeted drug delivery, and wound healing.

Ion cyclotron resonance heating is a critical method for directly heating ions in tokamaks, and a 6 MW ICRH system is planned for integration into the HL-3 tokamak as part of its next upgrade program. This study focuses on the characteristics of ICRH under the D(H) minority heating scheme for the stable-state scenario on HL-3, using the full-wave code AORSA. Simulations under the H fundamental frequency and D second harmonic demonstrate that predominant ion heating can be achieved at approximately (fsim 28) MHz and (k_{parallel }sim 8.4;text {m}^{-1}). Analysis of the fast wave dispersion relation reveals that the damping coefficient on ions increases sharply with the introduction of H minority ions. As the minority ion concentration increases, power deposition on H minority ions rises, while it decreases for D bulk ions. Additionally, mode conversion is observed near the ion-ion hybrid resonance layer, and theoretical analysis indicates that the critical concentration (X[text {H}]) for its occurrence is 6.1 %. Finally, the single-pass absorption efficiency exceeds 90 % for (X[text {H}]le10;%).

This paper investigates deep learning as a possible alternative of numerical technology computer-aided design (TCAD) device simulation to introspect device performance of FinFETs (fin field-effect transistors). TCAD simulator is used here to analyze performance of a nanoscale junctionless FinFET device with a set of input parameters and its corresponding output parameters. The dataset is generated by varying Channel length, Fin width, and Spacer length of the device, and is then used to train the deep neural network model. As the dataset is comparatively small, 4 hidden layers are included while creating the deep neural network model. In the output, figure of merits (FoMs) of the device, such as threshold voltage (V_th in Volt), subthreshold slope (SS in mV/dec), and drain-induced barrier lowering (DIBL in mV/V), are considered separately. Output obtained using this model is compared with the results generated through TCAD simulation. Performance of the deep neural network model is evaluated by calculating coefficient of determination (R²), mean absolute error (MAE), and root-mean-squared error (RMSE) and are found to be quite satisfactory. This research shows that the deep neural network model predicts figure of merits (FoMs) more efficiently, offering a compact model that requires less computing resource than TCAD simulation methods. This model is expected to be helpful for predicting fast and accurate device parameter for future technology nodes.

This paper intents to promote the mathematical model for non-Newtonian Darcy–Forchheimer on a microchannel with heat transfer of electrohydromagnetic peristaltic transport through porous medium. Slip boundary conditions for velocity and heat transfer are kept on channel walls. The Magnetohydrodynamic electro-osmosis peristaltic flow in a microchannel is derived under the framework of Debye–Huckel linearization approximation. The assumptions of long wave length and low Reynolds number approximations are also incorporated. By aggregating several factors, including axial velocity, temperature, pressure distribution, stream function, and Nusselt number, the current situation is categorized. The shooting approach based on RK-4 has been applied to assess the nonlinear equations. The significance of different parameters is visualized through the formulation of graphic results.

This study investigates the conformable fractional high-order nonlinear Schrödinger equation in the context of inhomogeneous optical fibers, a setting where classical models often fall short due to complex dispersion and memory effects. The motivation for selecting this model lies in its capability to capture nonlocal wave behavior more accurately using fractional derivatives. To obtain analytical wave solutions, we apply the Modified Extended Mapping Method (MEMM), which provides a broader and more systematic solution space than conventional techniques. Our findings yield novel families of exact solutions—including bright and dark solitons, exponential, singular, and Jacobi elliptic waveforms. The impact of the fractional-order parameter (alpha) on wave structure, velocity, and localization is examined, showing that it significantly modulates soliton behavior without altering peak magnitude. These results highlight both the modeling power of fractional calculus and the utility of MEMM in constructing diverse waveforms, offering potential for improved pulse shaping in advanced optical systems.

Lead-free ceramic system with a chemical composition of Sr_0.6Mg_0.4Nb_2(1-x)Ta_2xO₆ (x = 0.00, 0.02, 0.04, 0.06) was synthesized using a solid-state reaction method. The structural properties were analyzed using X-ray diffraction (XRD). The XRD results confirmed the formation of coexisting monoclinic and orthorhombic phases, and the lattice parameters varied with Ta⁵⁺ substitution. Dielectric studies revealed that the Curie temperature (T_c) increased with Ta⁵⁺ substitution up to x = 0.04, and the highest T_c (~ 62 °C at 1 MHz) for x = 0.04 suggests an optimal level of Ta⁵⁺ substitution, after which it decreased, indicating an optimal doping level for enhanced ferroelectric properties. Impedance spectroscopy revealed that the grain resistance decreased with increasing temperature, suggesting a thermally activated conduction process. Electric modulus analysis indicated a non-Debye relaxation behavior, with relaxation times decreasing as the temperature increased. The activation energies for both the DC and AC conductivities were calculated, and the highest DC energy gap (0.034 eV) was found for the x = 0.04 sample, revealing ionic conduction as the dominant mechanism. Ta⁵⁺ substitution significantly influences the dielectric and electrical properties of the material, making it a promising candidate for electronic applications, such as capacitors and resonators.