Jo Jan 31, 2023
Song Man Hyok, a section head at the Faculty of Earth Science and Technology, has proposed a new method to extract image features and to evaluate fractality based on two-dimensional (2D) continuous wavelet transform (CWT).
Multi-directional 2D CWT coefficients are used to determine the direction and magnitude of image intensity gradients directly unlike other methods using gradient components in horizontal and vertical directions. Image feature points are detected by comparing candidate directional 2D CWT coefficients at candidate points and their neighbors instead of gradient magnitudes or 2D CWT moduli used in traditional methods. It enables extracting multiscale image features including line singularities such as corners which are recognized to be hardly extracted by traditional methods. This offers an advantageous condition to study fractal objects consisting of lots of line singularities.
Assuming that the detected multiscale image features can reflect multiscale fractal measures used to evaluate fractality, that is, self-similarity across scales, he has proposed a method to evaluate fractality and calculate fractal dimensions using multiscale image features.
The application of the proposed method to theoretical fractal models proved that it is convenient and effective in extracting the image features of the models consisting of many line singularities and in calculating their fractal dimensions. It is concluded that the method is useful to deal with fractality evaluation of geoscientific objects such as coastlines and stream networks.
For more information, please refer to his paper “Image feature extraction and fractality evaluation based on two-dimensional continuous wavelet transform: Application to digital elevation model data” published in the SCI Journal “Fractals”.
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Jo Jan 26, 2023
As well known, the time dependent Ginzburg-Landau (G-L) equations are a powerful tool for study on popular characteristics in nonlinear dynamics, especially the dynamics of magnetic vortices in a superconductor close to a critical temperature in a magnetic field.
Constant efforts to improve the critical properties of materials in type-Ⅱ superconductors and apply it into a variety of areas by forming artificial pinning centers are being made. Hence, it is of great importance to study the magnetic vortices in a superconductor with artificial pinning centers using the G-L equations.
In recent years, many works on superconductors with pinning centers and defects distributed in a fixed quantity and different forms have been conducted. However, the dynamic study of the magnetic vortices in a superconductor with randomly distributed pinning centers in a normal state has rarely been reported.
Ryu Yu Gwang, a researcher at the Faculty of Physical Engineering, has reported the simulation results on the dynamic behaviors of the magnetic vortices in the above mentioned superconductor by using the time dependent G-L equations.
COMSOL and MATLAB were combined for the simulation. The time dependent G-L equations were solved numerically using the PDE model of the COMSOL program. The pinning centers were randomly distributed on the whole area of the superconductor. Then a distribution function p(r), which was used to determinate the size and sites of the pinning centers, was defined in a MATLAB and was directly called during the calculating process by the LiveLinkTM for MATLAB in the COMSOL program.
First of all, he analyzed the magnetization curves and the density of superconducting electrons as a function of the external magnetic field along the z-axis.
The simulation result showed that the vortices configurations and magnetization depend on the content of pinning centers and that the maximum magnetization values decrease exponentially as the content increases. The analytic expression of the maximum magnetization values as a function of the content was -4πMmax/HC2≈0.24+0.175exp(-6.14ω). Therefore, it can be defined that the higher content, the more decrease in the diamagnetism of a superconductor.
Next, he determined the content of pinning centers with the largest mixed state by modeling the number of the magnetic vortices trapped in the pinning centers. According to it, the suitable content for trapping more magnetic vortices in a type-Ⅱ superconductor with pinning centers was 20%.
This work will be useful for studying and understanding the dynamics of magnetic vortices in a type-Ⅱ superconductor with randomly distributed pinning centers in view of the circumstance that they are randomly distributed in the superconductor during its fabrication.
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Jo Jan 22, 2023
A research team led by Nam Sung Chol, a researcher at Mirae Academy of Science and Technology, has developed an agglutinated blood cell splitting flake with natural materials, which prevents aging by diluting thick blood.
If you wear it on your skin, you can keep yourself in good health without taking medicines or injections. It is very useful for middle-aged and elderly people.
The research team activated natural minerals with good property of far infrared radiation and mixed several additives, thus fabricating material with excellent radiation property. Then, with these materials, they continued to develop an agglutinated blood cell splitting flake, a simple functional health product that improves life activities and cures diseases by diluting thick blood.
The product radiates far infrared rays (2.5-15 ㎛) corresponding to the intrinsic absorption wavelength band of body cells and tissues with high efficiency, generates a large number of anions to improve the circulation of blood, restores the pH of the body to normal level (7.35-7.45 pH) and facilitates the uptake of nutrients and excretion of waste from the body.
Hence, it helps to prevent and treat various diseases if it is worn regularly.
By improving the microcirculation of blood, it activates the metabolism of organ tissues and it has good effect on headaches due to geomagnetic phenomena and circulatory disturbances, autonomic ataxia, limbs numbness, stress disorders due to excessive mental labor and on removing harmful cations due to electromagnetic waves from a long time of being in front of computers and televisions. It also stabilizes blood pressure, improves dyslipidemia (high hypolipoproteinemia, low hyperlipoproteinemia) and prevents stroke sequelae such as cerebral thrombosis and cerebral infarction.
After one to three months of wearing it, it proves to be effective: the face looks healthier and the skin gets elastic.
It is on a daily increase in its demand.
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Jo Jan 19, 2023
Ju Yong Chol, a section head at the Nano Physics Engineering Institute, and his research team members built an assembly-line microwave dryer for drying pills at pharmaceutical plants.
Microwave heating, compared to other ways of heating, is exellent in thermal efficiency and heating rate since it is focused on target objects only. It provides uniform thermal spread on the outside and inside of objects. Easy adjustment of microwave output leads to easy adjustment of heating rate. The dryer is simple in its structure and easy to operate. Microwave drying is being widely introduced in several fields like pharmaceutical industry and foodstuff industry thanks to its high production efficiency and high quality of products.
The assembly-line microwave dryer consists of a microwave generation sector, a control sector, a conveyor sector, a ventilation sector, a microwave leak checking sector, etc.
In the microwave generation sector are six magnetrons with 700W output. 2.8kW microwave is generated in real time by four of them in operation in turns and two cooling down.
In the control sector, there are electric circuit blocks to turn 4 magnetrons on and 2 magnetrons off. It controls the transmission speed of the conveyor.
In the conveyor sector, the belt on the bottom of the drying cavity is moved by the reduction motor with 90W output and 1 450r/min. The transmission velocity is 0~70cm/min.
In the ventilation sector, a 300L/min exhauster between the two drying cavities expels wet steam from the drying cavity generated during drying processes at the deflation speed of 3m/s.
In the microwave leak checking sector, the reflection-type microwave leak checker reflects the microwave propagated through the inlet and outlet of the drying cavity back into the drying cavity, which checks microwave leak and meets the permitted limit on the international standard.
The dryer proved to be effective in reducing the humidity of pills by 5% at 40kg per hour. Hygienic safety of products is ensured and production cost is reduced to half.
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Jo Jan 18, 2023
Pyon Chol Ung, a researcher at the Faculty of Communications, has developed and introduced a directive communication system in pits using electric-car lines.
The system enables route directive communication with moving electric cars through electric car lines in pits.
The pit directive transceiver consists of a digital signal processing unit, an interface with electric car lines, an audio signal interface and transmission and reception units.
The digital signal processing unit is responsible for carrying various commands and status signals between all peripheral devices, compressing and coding the audio data from the audio signal interface, digitally phase-modulating the audio data in succession, digitally demodulating the high-frequency signals from the interface with electric car lines and decoding the compressed audio data.
The interface with electric car lines plays a role of blocking DC and AC noises from electric car lines and passing only necessary high-frequency signals.
The audio-signal interface converts the analog audio signals generated from the microphone into digital signals and transfers them to the digital signal processing unit. It also converts the digital audio data generated from the digital signal processing unit into analog signals and outputs them through the speaker.
The transmission unit is made up of a backup amplifier, an output terminal and a coupling transformer. It amplifies digitally modulated high frequency signals to a certain degree. As the transceiver operates on a battery, it is important to enhance the efficiency of the output terminal. Therefore, a D-grade symmetrical amplifier with a field effect output transistor was chosen for the output amplifying unit.
The reception unit is comprised of a limiter, a band-pass filter and a high frequency amplifier. It amplifies the trivial signals coming from electric car lines with noise and removes unnecessary noises.
As the system does not need additional wired or wireless communication devices such as communication cable or radio repeaters but only existing electric car lines, it saves not only a huge amount of money for communication equipment but also a lot of labour necessary for its maintenance, repair and operation.
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Jo Jan 17, 2023
A research team led by Pak Chan Il, a section head at the IT Institute, has developed a land and environment information system “Mannyondaegye”, based on GIS.
The system offers inspection, measuring, search, analysis, statistic research and editing of a wide range of information in the field of land and environment such as land, forests, roads, rivers and streams, and national boundaries on PCs.
Several technologies and functions are realized in the system: 3D visualization of raster data, stratification and segmentation for visualization of big vector data in the land and environment sector, measurement of distances, areas, etc. on the map, spatial and non-spatial searches in various modes, addition and editing of spatial objects and subjects, and data import and export.
It guarantees scientific accuracy in GIS-based businesses for management of land and environment resources and serves as an integrated GIS, which means the possibility of an effective use in various sectors of the national economy.
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