Journal of the Korean Physical Society最新文献

Superhydrophobic surfaces have gained significant research attention for various applications, such as self-cleaning and microfluidics. To develop superhydrophobic surfaces, diverse materials and structures are used to reduce the surface energy. Specific coatings can control the intrinsic contact angle (CA) by reducing the surface energy of a material. In this study, we fabricated and evaluated polymeric superhydrophobic surfaces. The superhydrophobic surfaces exhibited microstructures consisting of two different polymers. To evaluate the wetting properties, we calculated the theoretical Cassie and Wenzel models of the surfaces and compared them to the experimental CA and roll-off angle (ROA). Furthermore, we measured the wetting properties of the surfaces by coating them with octafluorocyclobutane (C₄F₈) to confirm the effect of coating on the surfaces. This coated surface can control the wetting properties regardless of the material composition, demonstrating the stability of the superhydrophobic surface.

It is a long standing issue how non-Abelian entities take shape in macroscopic real space and are measured technically. Based on the gauge theory cast on recent spintronic researches, we obtained the expectation values of the Yang–Mills field strength in Rashba systems interfaced with a hard wall. This non-Abelian quantity is proportional to the spin density near the walls, when an external electric field is applied. The Yang–Mills field strength exerts a force on electrons, analogous to the influence of a magnetic field, and this effect is further clarified through the introduction of an effective scalar potential derived from a Landau-like gauge transformation and the analysis of electron’s classical trajectories. Our work demonstrates the feasibility of measuring the Yang–Mills field strength employing the magneto-optical Kerr effect, and provides calculated projections of the expected outcomes. Notably, these results, using gauge transformations, can be applied to other systems, including the Dresselhaus system.

Microwave sensor technology has transformed the food sector by providing fast and non-destructive methods to check food quality parameters. The present research provides a detailed investigation of the design and simulation of a flat microwave sensor specifically customized for use in the food industry. Initially, a thorough literature survey on the development of a robust and reusable ring resonator Sensor is performed for the Microwave frequency of L (1–2 GHz) and S (2–4 GHZ) bands. Then, the simulation of the microwave planar sensor with the different geometry and dimensions was done and dimensions were finalized having a maximum Return loss of − 20.177 dB at 2.377 GHz. Further, the structure was simulated on an FR4 with a Cu thickness of 0.4 mm and 1.6 mm substrate height. These simulations were performed to observe the change of resonant frequency by changing the material with their varied dielectric permittivity from 1 to 33.4 for varied food samples. Later, by conducting an electromagnetic performance analysis, the dielectric characteristics of different food samples are examined, providing insight into the sensor’s effectiveness in detecting electromagnetic signals. The sensor’s precision in detecting minute changes in food attributes is highlighted by sensitivity and accuracy assessments, establishing it as a promising tool for real-time monitoring and quality control. Finally, the limitations of the study and the scope for future research are explained, which are crucial for driving innovation in sensor technology across various industrial domains.

Taking into account the built-in electric field (BEF) effect, shallow-donor impurity (SDI) states in a strained type-II InGaN-ZnSnN₂/GaN quantum well (QW) are investigated variationally under hydrostatic pressure. Numerical results reveal that the SDI binding energy and BEF strengths of different well and barrier layers depend on hydrostatic pressure and structural parameters of the type-II QW. The BEF strengths in left and right wells, middle barrier, and barriers on both sides are proportional to the hydrostatic pressure. Meantime, the BEF strengths in well and/or middle barrier layers (barriers on both sides) decrease (increase) linearly with increasing the width of the well and/or middle barrier layers (barriers on both sides). The binding energy displays a maximum value as the well width decreases, and it increases linearly (decreases gradually) with the increment in hydrostatic pressure (middle barrier thickness). Moreover, the position of an impurity ion has a significant impact on the SDI binding energy. It is hoped that the obtained results will be helpful in improving the physical performance of tunable type-II InGaN-ZnSnN₂/GaN quantum wells (QWs) optical devices.

We apply the method of Hamiltonian reduction without isometry as a way to find exact solutions to Einstein’s equations. To find exact solutions, we introduce two spatial Killing vector fields to the Einstein’s equations obtained through the Hamiltonian reduction, and derive the Ernst-like equation in the privileged coordinates. By solving the Ernst-like equation, we found a four-parameter family of exact solutions, one of which is interpreted as a deformation of the general Kasner spacetime. We extend our method to spacetimes where two independent gravitational degrees of freedom co-exist and interact with each other, and obtain a set of two partial differential equations satisfied by them. If we substitute a pre-fixed diagonal mode into these equations, and then the equations reduce to a single non-linear partial differential equation, which is interpreted as the equation of non-diagonal mode of gravitational waves propagating on the “background” spacetime determined by the diagonal mode. We choose three simplest “background” spacetimes, and discuss the corresponding non-diagonal modes in each case.

At Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL), there is an ongoing consideration of employing elliptically polarizing undulators throughout the entire undulator line to enable polarization control in the soft X-ray undulator line. To utilize the elliptically polarizing undulators, the shorter focusing lattice for soft X-ray undulator line at PAL-XFEL is proposed. The FEL performance of the shorter focusing lattice is estimated by using Ming Xie’s fitting formula and is compared with the current focusing lattice. Due to the increased need for intersections in the shorter focusing lattice, there is a challenge where the effective length of the undulator becomes shorter compared to the current focusing lattice within the same length of the undulator line. Therefore, the use of quadrupoles employed in the hard X-ray undulator line at PAL-XFEL has also been taken into consideration to overcome the reduced effective length of the undulator by increasing the betatron phase advance. Based on the time-dependent FEL simulation results, it can be confirmed that the proposed shorter focusing lattice is sufficiently feasible without compromising FEL performance.

The effect of electrothermopolarization (ETP) on the structure and electrophysical properties (electret, dielectric) of polymer nanocomposites based on HDPE and hafnium oxide nanoparticles has been studied. The possibility of significant change in dielectric properties of HDPE/HfO₂ polymer nanocomposites at 3–7% nanoparticle concentration has been confirmed. The interactions of the polymer and nanoparticles are considered and the results of changes in the structure of HDPE/HfO₂ polymer nanocomposite in its volume and interphase zone before and after electrothermopolarization are presented. Spectroscopic studies of nanocomposites show that the introduction of nanoparticles is compatible in the presence of polyethylene. Results acquired via an optical microscope with magnification revealed that the nanocomposite HDPE/HfO₂ had a variety of morphology from oval, spherical, polygon, to irregular shapes depending on their snitches HDPE and HfO₂. HfO₂ affects the structure of the nanocomposites, which is observed by SEM, AFM, DSC and confirmed by infrared spectroscopy (FTIR).

Carbon-14 isotope separation technologies are important in various fields especially in the nuclear industry for radioactive waste treatment. Nowadays, laser isotope separation of carbon-14 based on photo-dissociation of formaldehyde molecule has become feasible. To develop this technology, spectral information of formaldehyde isotopologues is essential. We constructed a fluorescence spectroscopic setup including a tunable ultraviolet laser system to measure the carbon-14 formaldehyde spectrum. We also developed an evaporation process, involving self-enrichment of formaldehyde to obtain fluorescence signals using limited concentrations and amounts of samples. We demonstrate that the formaldehyde fluorescence spectra are in the 28,371–28,432 cm⁻¹ wavelength region, and identify the individual ¹⁴CH₂O peaks and estimate their absorption cross-sections.

In this paper, using soft-collinear effective theory, we study the invariant mass distribution for dijet production in (e^+e^-)-annihilation. Near threshold, where the dijet takes most of the energy, there arise the large threshold logarithms, which are sensitive to soft gluon radiations. To systematically resum the logarithms, we factorize the scattering cross-section into the hard, the collinear, and the soft parts. And we additionally factorize the original soft part into the global soft function and the two collinear-soft functions, where the latter can be combined with the collinear parts to form the fragmentation functions to jet (FFJs). The factorization theorem derived here can be easily applicable to other processes near threshold. Using the factorized result, we show the resummed result for the dijet invariant mass to the accuracy of next-to-leading logarithms. We have also obtained the result in the case of the heavy quark dijet and compared it with the case of the light quark.