Jo Nov 6, 2024
The astronomical chart is another name of the picture of constellation.
“Honchonjondo” shows the level of our country’s astronomical development in the eighteenth century.
“Honchonjondo” literally means “a picture of the whole sky”. Showing the stars in the night sky on a sheet of paper, it gives a description of astronomical phenomena and explanation about them, and keeps a record of astronomical constants.
“Honchonjondo” chiefly shows our own astronomical development dating from the ages of the first Korean state founded by King Tangun, with a brief account of the western astronomical development until the first half of the eighteenth century.
All the astronomical contents found in “Honchonjondo” are a precious astronomical heritage of our country, which shows the astronomical development of that time. The national treasure that enriches the treasure house of Eastern astronomy is now preserved in the Grand People’s Study House.
“Honchonjondo”, which is permeated with the wisdom and intelligence of the Korean nation, was registered as a world heritage of UNESCO in May, 2023. This is a brilliant fruition of the Workers' Party of Korea's policy of national cultural protection, and a significant occasion for inspiring the Korean people with national pride and self-esteem.
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Jo Nov 5, 2024
In order to realize automated and unmanned production processes, it is necessary to supervise and control the production process in real time, and check and evaluate the quality of products. Image processing units such as digital cameras are usually used to implement it. Recently, high-resolution cameras are used to improve the accuracy of data. The higher the resolution is, the bigger the amount of data is. Therefore, data transmission rate between computers and peripherals should be increased.
USB3.0 is a computer interface protocol that makes possible up to 5Gbps of data transmission by means of advanced techniques such as full-duplex transmission mode by multi channels, burst function using integrated packets and high-speed encoding technique by 8b/10b encoding, and its application technology has been widely studied for its good hardware connectivity and ease of use.
Ri Pyong Chol, a researcher at the Faculty of Information Science and Technology, has proposed a configuration and design of a USB high-speed transmission system that can achieve a USB3.0 data transmission rate of up to 3.2Gbps.
First, he combined a USB3.0 chip and Cyclone II FPGA to configure a high-speed data transmission system. Then, he programmed a firmware to set the data packet size and buffer size for maximum data transmission rate of the USB port. He also designed FPGA internal logic to increase the data transmission efficiency through the synchronous SlaveFIFO controller, the internal buffer, and the external I/O controller.
Finally, he measured the data transmission performance from the development system to the computer with a test program, and evaluated the efficiency of the proposed system design method.
He confirmed that the proposed method could ensure the data transmission rate of up to 3.2Gbps.
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Jo Nov 2, 2024
Pine Island on Sea Chilbo is an island off Pochon-ri, Myongchon County.
It is one of the scenic spots in Sea Chilbo of Mt. Chilbo, which has been widely known as “Kumgang in North Hamgyong Province” from olden times.
The island is not too far from the land. It was originally a single one but a crack widened gradually to split the island into two.
On the mid-slope of the island is a cave called “Dragon Cave”.
The island is covered mostly in pine, oak and maple.
The pine island has been known as a noted place of Sea Chilbo from olden times for its wonderful scenic beauty.
The pine island is of academic significance and scenic worth.
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Jo Oct 31, 2024
There are two main schemes of charging scheduling of a mobile charger (MC): periodic and on-demand. The latter schedules on-demand charging of a BS or MS, whose order is determined by temporal and spatial factors of request nodes. Recently, several intelligent on-demand charging scheduling schemes combined with multi-criteria have been proposed. Multi-criteria that conflict with each other, such as residual energy, distance to the MC, energy consumption rate, traffic relay load of charging request nodes, etc., play a key role in determining the charging priority of charging request nodes. However, which theory should be applied to determining the most suitable charging order of request nodes with such contradictory criteria is still a challenge that needs urgent solution.
Among the various multi-criteria decision making (MCDM) methods, the FAHP-TOPSIS method combined with fuzzy analytical hierarchy process (FAHP) and the technique for order preference by similarity to ideal solution (TOPSIS) are most widely used.
From the inspiration that an integrated MCDM in charging scheduling using multi-criteria could be effectively available throughout the whole charging scheduling process, Ri Man Gun, an institute head at the Faculty of Communication, has proposed a novel charging scheduling scheme based on an integrated FAHP-VWA-TOPSIS (iFVT).
Using an iFVT, he has also proposed a method of accurately calculating the relative weights of multi-criteria and determining the most suitable next-to-be-charged node by combinatorial evaluation of multi-criteria of request nodes
You can find the details in his paper published in “The 14th international Conference on Computing, Communication and Networking Technology (ICCCNT 2023)”.
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Jo Oct 29, 2024
Subcooled flow boiling is widely used in many cooling systems due to its high cooling effect. In such systems, it is very important to accurately analyze the boiling heat transfer behavior of working fluid. Therefore, there have been several researches on accurately analyzing the behavior of subcooled flow boiling heat transfer by using commercial Computational Fluid Dynamics (CFD) codes. Most of the researchers have used the RPI (Rensseler Polytechnic Institute) model within Eulerian multi-phase framework in their CFD simulations of subcooled flow boiling heat transfer.
In a word, there have been many studies on the CFD analysis of subcooled flow boiling and a lot of progress has been made in terms of accuracy. However, most of the previous works for CFD simulations considered water as the working fluid, and the works for the CFD simulations with CO2 as the working fluid are rare.
Ma Kuk Chol, a researcher at the Faculty of Heat Engineering, has developed a mathematical model to simulate the subcooled flow boiling of CO2 by utilizing the Eulerian multi-phase model combined with the RPI and IAC models, and solved the model by means of the CFD solver, ANSYS FLUENT 19.3.
Thus, he proved that the coefficient of heat transfer is greatly affected by bubble waiting time coefficient (CWT) and critical Weber number (Wecri) and determined reasonable CWT and Wecri.
The details are found in his paper “Determining of bubble waiting time coefficient, critical Webber number and turbulence model for modeling of subcooled flow boiling heat transfer of CO2 at low temperature” in “Applied Physics A” (SCI).
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Jo Oct 26, 2024
Dye solar cells (DSCs), which are based on photosensitization of dyes adsorbed on wide-bandgap oxide semiconductors such as TiO2, have attracted a great deal of attention on account of their semitransparency, color harmony function and simple fabrication processes.
Transparent glass or polymer films with a conductive oxide layer (TCO electrode), such as FTO/GLASS and ITO/PET(Polyethyleneterephthalate), are often used as the substrates in DSCs because of their good conductivity and outstanding transmittance. However, these TCO electrodes account for a lot in the price of inorganic–organic hybrid solar cells such as dye and perovskite solar cells due to their dependence on exclusive deposition techniques.
Ti metallic substrates, such as Ti wire, Ti mesh, Ti foil and the like, are deemed to be a good choice to replace TCO electrodes. However, the Ti metallic substrates suffer from certain shortages. For example, metal foil has no transmittance, metal mesh owns a small effective area for accepting sunlight and metal wire is hard to support the manufacture of large-scale DSCs. Moreover, the high price of titanium substrates limits its wide application.
Jon Sang Mo, a researcher at the Faculty of Chemical Engineering, has proposed a new method of manufacturing a porous Ti back contact layer by using a facile printing method in normal ambient conditions.
In addition, conjugating the new back contact electrode technology with the traditional monolithic structure using the carbon counter electrode, he fabricated low-cost TCO-free DSCs. These four-layer structured DSCs consist of a dye-adsorbed nanocrystalline TiO2 film on a glass substrate, a porous Ti back contact layer, a ZrO2 spacer layer, and a carbon counter electrode in a layered structure, and the interior of the layers is filled with iodine/triiodide redox electrolyte.
For more information, please refer to his paper “Journal of Saudi Chemical Society” in “TCO-free dye solar cells based on Ti back contact electrode by facile printing method” (SCI).
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