Jo Jun 30, 2026
Real-time and omnidirectional observation of the ocean is of great significance in protecting the marine environment while enabling mankind to effectively develop and utilize marine resources. In particular, ocean currents and wind observation are very important in the observation of marine environmental quality. Ocean currents are the large-scale and relatively stable flow of seawater, which is one of the most important and universal forms of motion of the sea water, playing an important role in the stability of the global climate and ecological balance, and having many adverse effects on the livelihood and production of coastal people and the exploitation and utilization of the ocean. As a result, current measurement technology has been one of the main focuses of the oceanography. In addition, ocean wind observation has important significances in ensuring navigation safety, preventing disasters, assisting climate research, improving environmental protection and promoting resource exploitation and fisheries production.
Currently, ocean observation is mainly carried out by oceanographic buoys, unmanned vessel surveillance and satellite remote sensing. Ocean observation buoys, which have the longest history of development, can be mainly divided into two types; underwater observation buoys for specified points and surface drifting buoys that drift along the ocean current.
Of course, observations by unmanned ships and satellite remote sensing have been applied in ocean water measurement, but they cannot accurately measure ocean water at exact locations required by users, and real-time and long-term measurements are more difficult. In ocean water measurement using observation buoys, accurate measurement data can be directly measured and wirelessly transmitted in real time at any location required by observers.
Kim Chol Min, a researcher at the Faculty of Naval Architecture and Ocean Engineering, analysed the influence of the yaw and pitch characteristics of observation buoys on the measurement of the direction of the ocean current and wind direction, proposed a simple and reasonable measurement method, and verified its effectiveness through simulations and experiments.
The simulations and experiments demonstrated high accuracy of ocean current and wind direction measurements. The absolute error of the ocean current direction measurement is less than 0.5%, and 16 wind directions were accurately measured.
For further details, please refer to his paper “One method to measuring ocean current and wind direction from marine buoys” in “Journal of Atmospheric and Oceanic Technology” (SCI).
...
Jo Jun 29, 2026
The opinion dynamics model which is being widely investigated by physicists can be largely divided into two types: discrete opinion models and continuous opinion models. The former uses a finite number of values to express agents’ opinions. The latter, unlike the discrete opinion models, takes a real number to represent agents’ opinions.
Some researchers studied the SJT model, one of the continuous opinion models. They proposed two thresholds: an acceptance threshold (d1) and a repulsion threshold (d2). According to their rules, when the difference in the inner opinion between two randomly selected agents is smaller (or larger) than d1 (or d2), the agents simultaneously update their opinions in the direction where their difference gets smaller (or bigger).
Jang Paek San, a researcher at the Institute of Nano Science and Technology, proposed a modified SJT model with a new opinion updating mechanism. Unlike the previous works, every individual affects the others’ opinions and the extent of the influence depends only on the magnitude in the opinion difference. To incorporate the convergence parameter of the assimilation effect and the divergence parameter of the repulsion effect into one parameter, he introduced a new function and used Monte Carlo simulations to study the opinion evolution process of the new model.
The simulation results showed that as d1 increases, the number of opinion clusters increases, but with increasing d2, the opinion dynamics changes from a bipolarization of opinions to a consensus of opinions.
For more information, you can refer to his paper “Social Judgment Theory model with continuous interaction between assimilation and repulsion mechanisms” in “SN Social Sciences” (SCI).
...
Jo Jun 28, 2026
The introduction of a self-mixing (SM) displacement sensor into the measurement of mechanical vibration is an effective choice due to the characteristics of the SM interferometry (SMI). This is because the SMI has very favorable advantages for field measurement, for instance, high measurement accuracy, adaptability to any reflective surface, low cost, etc. Moreover, the compactness of SM sensors makes it easy to develop a hand-held portable device.
The key to developing a hand-held SM sensor is how to remove the hand-induced parasitic vibration. Since the removal of parasitic vibration is important for the accuracy of SMI, there have been many studies, divided into hardware-based and software-based methods.
Jang Kum Hyang, a researcher at the Institute of Mirae Industrial Technology, proposed a method of removing the hand-induced parasitic vibration based on data fitting, which is very simple and suitable for a hand-held self-mixing displacement sensor for the measurement of mechanical vibration.
The measurement accuracy that the proposed method provides is less than 30 nm.
If further information is needed, please refer to his paper “Removal of parasitic vibration in a self-mixing measurement for mechanical vibration based on data fitting” in “Applied optics” (SCI).
...
Jo Jun 26, 2026
Previous papers suggested an end processing function, an enhanced smooth continuous condition and a method to overcome the defects of the precedent modified analytic embedded atom method (EAM) potentials considering the farther neighbor atoms by fitting model parameters to one or two structure energy differences. The structure energy differences and the binding energy curves as a function of volume calculated by these potentials are better than the calculation results by precedent modified analytic EAM (MAEAM) considering the farther neighbor atoms in the agreement with the experimental results and the Rose equation curves. The original MAEAM proposed only one many-body potential form for body-centered cubic (BCC), facet-centered cubic (FCC) and hexagonal close packed (HCP) metals. So, this potential has been frequently used in the calculation of the properties of metals and alloys. However, as the MAEAM considering farther neighbor atoms suggested different potential forms for different structures, using this potential is inconvenient and the application examples are rare. But it still gives better results than the original MAEAM.
Therefore, it is necessary to adopt a common potential form which can be applied to all kinds of metals such as the original MAEAM, simultaneously considering the farther neighbor atoms.
Ho In Chol, a researcher at the Faculty of Information Science and Technology, suggested a common pair potential form which can be applied to the three kinds of the typical structures of metals and explain the structure stabilities, the structure energy differences and the dependence of binding energies on lattice constants well.
The results by the common-form potentials of the modified EAM for the BCC transition metals Cr, Fe and Mo are in good agreement with experimental data and other calculation results, and significantly better than the precedent potentials for the BCC metals.
For further details, please refer to his paper “Common potential form of modified embedded atom method and BCC transition metals Cr, Fe, and Mo” in “Indian Journal of Physics” (SCI).
...
Jo Jun 25, 2026
With the rapid development of nanotechnology, nano-composites with nano-additive agents play an important role in many fields. Nano additive agents take various types and some of them are embedded in the surface of the material to enhance its strength or hardness. Therefore, the studies for understanding the mechanical behavior of nano-inclusions in media are increasing day by day.
The scattering of SH waves was often applied to study the dynamic response around the different kinds of inclusions in the half space. From the preceding investigation results, it can be seen that the studies of the surface/interface effects on the dynamic behavior of inclusions are restricted to the circles. Furthermore, the researches on the effects based on the scattering theory of SH waves have been done much less than others.
Jang Paek San, a researcher at the Institute of Nano Science and Technology, investigated the scattering of SH waves by a semi-circle nano-inclusion embedded in the half space surface using the surface/interface elastic theory.
The numerical simulations showed the following. First, as the size of the inclusion decreases to a nanoscale, the value of DSCF (dynamic stress concentration factor) also decreases, which means that the interface effect tends to suppress the perturbation of the DSCF. Second, when the nano addition agents are added into the surface of a medium, the rigidity of the nano-inclusion should be much smaller than that of the medium. Third, in the case of nanoscale inclusion, the surface/interface effect should be considered.
You can find the details in his paper “Dynamic Stress around a semi-circle nano-inclusion embedded in the half space surface” in “Journal of the Brazilian Society of Mechanical Sciences and Engineering” (SCI).
...
Jo Jun 24, 2026
Determination of uranium is very important for effective use of seawater. Uranium is the most stable of all the elements in the ocean. The concentration and pH of uranium in the seawater differ a little according to the region and the depth, but the averages are 3.3×10-6g/L and 8, respectively.
Yun Chol Hun, a researcher at the Institute of Analysis, has reported a new combined method for the determination of trace uranium in seawater.
First, he added ferric chloride to 1L of seawater sample and adjusted the pH to 4. Then, he placed the solution at 80℃ for 30 min to coprecipitate uranium with iron hydroxide. After that, he dissolved the precipitate in nitric acid and electrodeposited it in EMIMBF4 to determine uranium by ICP-OES.
He evaluated the coefficient of diffusion (D) of electrodeposition of U(VI) on platinum electrode in EMIMBF, which was 3.31×10−9cm2/s. The electrochemistry experiments indicated that the reduction of U(VI) at platinum electrode in EMIMBF4 was a quasi-reversible single step two-electron transfer. The percent of chemical coprecipitation recovery of U(VI) was 98.9% and the recovery in electrodeposition was 99.5%.
For more information, please refer to his paper “Determination of uranium in seawater using chemical coprecipitation-ionic liquid electrodeposition by ICP-OES” in “Journal of Radioanalytical and Nuclear Chemistry” (SCI).
...