Jo Feb 12, 2024
Ryu Chang Sik, a section head at the Faculty of Distance Education, has developed a large-scale online lecture system in relay mode.
The relay system is an information system capable of providing thousands to tens of thousands of simultaneous subscribers with real-time online education on a nationwide scale in three-tier relay mode through central server, intermediate server, terminal server and terminal on a computer network.
The system aimed to narrow the difference in the level of education between the capital and other provinces and between cities and countries by providing real time or non-real time lectures given by competent lecturers from the capital and other cities to all the schools across the country. Therefore, it has to be designed to transfer real-time lecture data from the capital to provinces, from provinces to counties and from counties to schools, not from the central or provincial server to all terminals.
First, he newly designed and realized a three-stage relaying system via centre-province-county-terminals. Then he solved some technical problems like increasing compression ratio and reducing network load to deal with increase in network traffic per subscriber of three to five times more than the existing video conferencing system, and enhancing the real-time transmission of video and audio data in the relaying mode for perfect performance of online lectures.
Second, he applied load balancing to avoid network overload at provincial, city and county network stations.
Next, as relay servers are installed in all provinces and hundreds of counties across the country, he correspondingly solved the problem of transferring and synchronizing history data between central, provincial and county servers so that a detailed report on attendance in the provinces, cities and counties can be made to the center.
Finally, he made it possible to hold multiple conferences including academic uniformity as well as online lectures.
The proposed system will make a positive contribution to narrowing the differences in education levels between the capital and other provinces by stepping up IT-based education.
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Jo Feb 10, 2024
Jon Song Won, a researcher at the Faculty of Materials Science and Technology, prepared carbon nanotube reinforced aluminum composite for wire and cables core using carbon nanotubes.
Nowadays, carbon nanotubes, one of carbon nanomaterials, are widely used as reinforcement materials for various composites due to their superior properties.
Carbon nanotube reinforced aluminum composite wires for wire cables produced by new technology can improve mechanical and electrical properties including tensile strength, elongation, bending number and specific electrical resistance more than conventional aluminum wires, and production of wire cables using low purity aluminum is possible.
The preparation process of carbon nanotube reinforced aluminum composite core for wire cables consists of surface treatment of carbon nanotubes, dissolution of aluminum, addition and dispersion of carbon nanotubes, continuous casting and continuous rolling processes.
In order to examine the effect of carbon nanotubes on the texture and properties of carbon nanotube reinforced aluminum composites for wire cables, he performed a tensile test, a repeated bending test, a hardness test and a microstructure analysis.
He drew the following conclusions.
When the content of carbon nanotube is 0.3%, the tensile strength of carbon nanotube reinforced aluminum matrix composites is 250 MPa and the elongation ratio is 5%.
As the carbon nanotube content increases, the particle size of the composite decreases significantly and the shape turns spherical.
His method is more reasonable and economical than the previous methods as there is no need for new equipment for improving the properties of wire and cable cores.
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Jo Feb 8, 2024
A research team led by Han Jong Su, a section head at the Faculty of Earth Science and Technology, has developed an analysis method of geological structures of irrigation canals and waterway tunnels by magnetic field survey.
Finding out about geological basement is of primary importance for qualitative guarantee of watercourse construction and its safe operation.
Magnetic survey is one of the cheap but speedy and accurate methods.
Magnetic survey based on magnetic susceptibility is considered effective for detecting horizontal and vertical position of boundaries between geological bodies in building a shallow subsurface construction. This method has already contributed to the building of a 100 km watercourse by analyzing the depth and outline of the weathered layers, geological structure and karst.
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Jo Feb 7, 2024
A research team led by Kim Won Ok, a researcher at the Faculty of Information Science and Technology, has developed a system for detailed survey of forest resources whereby detailed indices such as the number, height, species and volume of individual trees can be obtained from UAV RGB images.
Past surveys of forest resources involved many investigators on the spot, but the system makes surveys easier, scientific and rapid only by UAV.
The system consists of two parts ― one is for obtaining orthomosaic images, digital surface model (DSM) and digital elevation models (DEM) from UAV images and the other is for detecting individual treetops and classifying tree species based on these data in a certain area.
To guarantee the quality of UAV images for survey, it is important to properly determine the photographing parameters of UAV, so through lots of photographing and analysis of UAV images she set photographing interval as 2~2.5s, photographing altitude as 70m from the hillside of the area and air speed as 2.5~3m/s.
This system ensures over 85% of treetop detection rate and over 85% of classification accuracy, and reduces labor for survey down to one sixth.
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Jo Feb 6, 2024
Ozone is very good at oxidizing bacteria, viruses, mold and other harmful organic substances existing in water and air by reacting with them.
The strong anti-bacterial effect of ozone is more and more expanding its application, and therefore many industries employ mass output ozone generation technology.
Environmental remediation by industrial application of ozone is a technology that uses germicidal ozone gases to obtain clean air and water and to improve the environment by disinfecting air, water, walls, hand tools, etc. contaminated with bacteria, viruses, organic and inorganic substances.
Many problems arise with industrial application of mass output ozone generators including stability of power supply and generator tube, enhancement of ozone generation efficiency, design of ozone gas mixers for energy efficiency enhancement and rational use of produced ozone, etc.
Won Chol Hyok, a researcher at the Faculty of Physical Engineering, has finally succeeded in making a mass output ozone generator with domestic materials by solving these problems through a lot of efforts.
First, he newly designed a discharge tube of the ozone generator. He chose ozone generation by dielectric barrier discharge and used quartz glass and alumina ceramic as dielectric material. The generator tube was designed to be cooled by water.
Next, power supply and control system were newly designed. He designed a new overvoltage absorption circuit to prevent device breakdown due to back EMF that could occur with increasing power of the ozone generator and made an experimental verification of its characteristics. In order to realize an intelligent control over the system, he used an embedded chip (STM32F series) for a control over power supplies, and adopted a new kind of control algorithm.
Finally, he designed a new type of ozone mixer. The ozone mixer, which is made up of venturi, mixing tank, pump and inlet-outlet pipelines, dissolves ozone into water.
The generator he manufactured can be applied to various fields such as drinking water disinfection, wastewater disinfection, aquaculture, poultry farming and so on.
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Jo Feb 2, 2024
In old days our people used to make fried glutinous rice cake, sweet food on the lunar New Year’s Day.
To make fried glutinous rice cake, glutinous rice flour is first kneaded with liquor to be fermented before it is formed into certain shapes and dried. Then, it is fried in oil and plastered in corn syrup or honey. Finally, it is dressed with fried rice, sesame, pine nuts, etc.
Fried glutinous rice cake, sweet food peculiar to our nation, was enjoyed by children as it is sweet and tasty and of high nutritive value. When children made a bow to elderly people on the morning of the New Year’s Day, they would get fried glutinous rice cake as a return gift.
According to a historical document of the feudal Joson dynasty “Tongguksesigi”, fried glutinous rice cake was considered indispensable for guest service on the lunar New Year’s Day, and “Ryolyangsesigi” wrote it was the best of all the dishes prepared for memorial service on the lunar New Year’s Day and the lunar January 15.
As mentioned above, Korean people tried to create their own dietary culture with materials found in their native places.
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