Jo Aug 16, 2023
The loupe developed by a research team led by Kang Thae Hyok, a researcher at the Faculty of Mechanical Science and Technology, is a portable optical instrument for successful performance of microsurgical operations.
This instrument can be used to raise the accuracy of performing operations by magnifying internal structure of eyes invisible to the naked eye.
It is made up of an optical unit, an illumination unit, a control unit and a glasses frame.
The optical unit is composed of two binocular tubes. Its magnification is 3X, the working distance is 250~300mm and the field of view is 40mm.
1W/3V LED is used for illumination.
The control unit is a device to adjust the distance of axes of the two tubes to the space between eyes. The rack pinion installed in the control body adjusts the space within 50~75mm by the knob.
They established the optimum optical system for convenience and accuracy of operations and solved technological problems arising in the minimization of the size of the instrument.
The loupe they have developed will find wide application in observation of fine structures and micromanipulation as well as in clinical practices like operations on eyes and blood vessels.
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Jo Aug 14, 2023
A research team led by Won Ju, a researcher at the Nano Physics Engineering Institute, has developed an effective reflector for microwave leakage prevention.
When applied to organisms, microwave changes the potential and charge on both sides of the cell membrane, thus impairing its function, destroying normal metabolic and physiological activities of the cell, and changing the quality of physiologically active substances. All these result in drying and sterilization of microorganisms.
Microwave is absorbed in large quantities into dielectrics such as wood and plastic or water-containing materials, but it is reflected on metal surfaces. When microwave is reflected from material, the material cannot be heated. Instead, the material is heated only by absorbing the energy of the microwave. It means that leakage of microwave leads to low efficiency of microwave equipment.
The reflector for preventing microwave leakage consists of a cuboid structure (except for two sides of the inlet and outlet) whose c-shaped reflective elements are arranged at regular intervals in columns in an indented way.
The width-depth-height ratio (a:b:c) in the reflector is 3:2.5:1.
When the microwave propagated inside the microwave device enters into the input/output channel region, it is reflected by the reflective elements so that the microwave does not come out but returns inside, which leads to significant reduction in the leakage of microwave.
He proposed a geometric structure of a leak suppressor that can effectively prevent microwave leakage in a microwave drying sterilizer, and carried out a simulation on microwave propagation inside the suppressor so as to determine its dimension and position.
As a result, the efficiency of a microwave drying sterilizer was improved and at the same time, production efficiency and quality of products were improved with less power.
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Jo Aug 11, 2023
A research team led by Choe Kyong Hyok, a researcher at the Faculty of Mechanical Science and Technology, has newly built an automatic frozen fish block packaging machine to ensure convenient packaging processes and higher productivity.
This machine is for wrapping in thin films frozen fish blocks entering through a thawing machine before storing.
The machine consists of a feeding conveyer, a longitudinal packaging conveyer, a lateral packaging conveyer, a longitudinal adherer, a lateral adherer and a film feeding system.
This machine keeps its feeding velocity at 0.5m/s in order to eliminate inertia of each 10-kilogram frozen fish block when they are stopped.
First of all, each frozen fish block entering through the thawing machine is fed to the feeding conveyer from the longitudinal direction. Each frozen fish block coming out from the feeding conveyer is fed to the longitudinal packaging conveyer pushing a vinyl film linked from top to down. When each frozen fish block is located in place, the longitudinal packaging conveyer is stopped and the longitudinal adherer works for packaging. This time the proximity detector detects the correct position of frozen fish blocks to ensure perfect joint.
Then, the longitudinal packaging conveyer starts up to move the blocks to the lateral packaging conveyer. The same process takes place for lateral packaging.
Finally, the blocks are forwarded through the lateral package conveyer to the transshipping device.
The productivity of this packaging machine is 900 blocks per hour, the output of the conveyer motor is 0.37kW and the reduction ratio is 15.
The packaging machine will find wide application at fisheries for automatically packaging 10-kilogram frozen fish blocks, and for making storage, transportation and supply of them convenient and clean.
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Jo Aug 10, 2023
A research team led by Kim Song Ho, a section head at the Faculty of Automation Engineering, has developed a multi-agent reinforcement learning experiment system using a process simulator.
In recent years, reinforcement learning has been considered as a learning method for acquiring behavior rules that can be flexibly adapted to complex and diverse environments, and many multi-agent reinforcement learning methods have been developed to effectively perform, in cooperation with several agents, complex problems impossible with one agent.
The multi-agent reinforcement learning experiment system consists of a process simulator, a controller, and an IPC.
On the IPC's experimental program interface, a user can simulate a learning process in detail by randomly changing the multi-agent system configuration and reinforcement learning parameters.
The change of the convergence rate according to the mutual cooperation algorithm of the agents can also be observed.
The research team developed a new multi-agent collaboration algorithm and demonstrated its superiority over previously developed ones.
This system can be used to develop multi-agent collaborative learning algorithms and to simulate real processes.
It can also offer practical trainings on intelligent supervisory control to students majoring in management system engineering and generalization to educational units across the country.
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Jo Aug 7, 2023
Ri Chang Myong, a researcher at the Faculty of Distance Education, has developed a virtual tour supporting system by modeling the images of places for a visit.
The system consumes less time and effort for modeling and at the same time the photos further raise feeling of actuality.
The system consists of a panoramic image generation module, a modeling and virtual tour editor, a virtual tour module and a management module.
In the panoramic image generation module, image stitching technology is employed so that the photos are stitched to produce images with wider FOV.
In the edition module, the panoramic images generated in the previous stage are modeled. Here, several functions are added for interaction.
The virtual tour module is for a virtual tour. The courses of tour are recorded through the network.
In the management module, registration, modification, deletion and upgrade of objects for virtual tour are performed.
Ordinary cameras can also be used for the system.
It will prove to be useful in the education sector. It will save a lot of time and money by making it possible for students to do production practices, visits and school trips on computer without bothering to go out to the spot.
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Jo Jul 31, 2023
Direct and inverse scattering problems play a central role in areas such as radar, sonar, geophysical exploration, and nondestructive testing and they have been widely studied in recent years. In particular, the uniqueness and existence of direct scattering problems, the reciprocity relation and completeness of electric far field patterns, etc. are basic in the inverse scattering theory.
In most applications as well as in geophysical exploration and nondestructive testing, it is, in general, assumed that the scattering obstacle is buried in a piecewise homogeneous medium and is partially coated by a dielectric. For example, underground mines and submarines are embedded in a piecewise homogeneous medium with air-earth and air-water interfaces and they consist of metallic and nonmetallic parts.
Kim Yun Chol, a section head at the Faculty of Applied Mathematics, has studied uniqueness and existence for a direct electromagnetic obstacle scattering problem in a piecewise homogeneous medium, some properties of a scattered field and a far field pattern, including boundedness, reciprocity relation and completeness, where it is assumed that the obstacle is a partially coated perfect conductor and the incident field is given by the electromagnetic plane wave.
He has conclusively proved that the electric far field pattern of the solution of the scattering problem of the electromagnetic plane wave as well as uniqueness and existence for the solution of the direct problem of scattering of time-harmonic electromagnetic waves by a partially coated obstacle buried in a piecewise homogeneous medium satisfies the reciprocity relation, and that the set of electric far-field patterns is complete in a Hilbert space.
These results are of great significance to the study on the solution of inverse electromagnetic scattering problems, i.e. determination of the location, shape and physical property of obstacles from the knowledge of electric far field patterns.
For further information, please refer to his paper “Electromagnetic wave scattering by a partially coated obstacle in a piecewise homogeneous medium” in “Mathematical Methods in the Applied Sciences” (SCI).
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