Jo Jul 20, 2023
It is very important to improve rapidity and correctness of analysis.
A powerful chemical imaging analysis system by AI technology has been developed by a research team led by Ri Ok I, a lecturer at the Faculty of Distance Education, and Kim Yong Ok, a section head at the Faculty of Chemical Engineering. They introduced deep learning technology, a branch of mechanical learning that has been accepted as an innovative one in the field of AI technology in recent years, thus making it labor- and cost-effective.
They first developed a method of extracting the main colour from a solution image taken by a camera and converting it into RGB values.
Then, they built a neuron network by deep learning technology. Learning data for the engine should be more than ten thousand sheets but construction of as many experimental data is not easy, so experimental data had to undergo processing for improving learning efficiency.
Finally, they designed it so that the RGB values are put into the engine and output values are processed to show analysis results.
On the basis of this, they developed an analysis system for Android-based smart phones or tablet PCs.
They applied the system to the analysis of Ni plating solution.
The result showed that analysis of plating solutions could be conducted promptly and easily any time with high accuracy without recourse to any kind of chemical reagents and analytical apparatus, and that it can be used by non-professionals too.
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Jo Jul 19, 2023
Today, exhaustion of fossil fuel and serious environmental pollution earnestly require active use of renewable energy resources such as wind, geothermal and solar energies for power generation.
Particularly, geothermal resources with low temperature heat source have been developed extensively for power generation all over the world by using the Organic Rankine Cycle.
A research group led by Ri Hung Nam, a section head at the Faculty of Heat Engineering, has developed a 50kW geothermal power generation system that harnesses hot spring water.
The system consists of an evaporator, a steam turbine, a condenser, a preheater, a hot spring water pump, a working fluid pump and a cooling water pump and so on. NH3 (R717) is used as working fluid.
In the evaporator, the hot spring water from the intake well by the pump produces steam by heating working fluid with low boiling point from the preheater. The high pressure saturated vapor from the evaporator expands through the steam turbine to the pressure of condenser. At the same time, it drives the turbo-generator to generate electricity. In the condenser, the working fluid is condensed with the help of the cooling water.
The condensed working fluid is fed to the preheater by the pump.
In the preheater the working fluid from the condenser is heated to be saturated liquid with an evaporating temperature by the hot spring water from the evaporator. Hot spring water from the preheater is used for heating of a building. And the heated working fluid in the preheater enters into the evaporator and then the above cycle is repeated.
This system has horizontal bundle heat exchangers (evaporator, condenser and preheater) and a single impulse stage steam turbine.
In the evaporator hot spring water flows into the tube and working fluid evaporates outside. In the preheater, working fluid flows into the tube and hot spring water flows out of it.
In the condenser, cooling water flows into the tube and working fluid vapor is condensed outside.
The system saves 120~180t/h of coal a year and it can contribute to the prevention of global warming. It is available in all areas with over 70℃ of heat sources such as hot spring and wasted heat.
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Jo Jul 17, 2023
A research team led by Jang Pok Nam, a section head at the Faculty of Metal Engineering, has established an Nd-Fe alloy production process for rare earth magnet by using rare earth resources in our country.
Because of its great activity and its good properties, rare earth metal is widely used in various fields including the metallurgical and electronic automation industries and the field of its application is being widened more and more.
Especially, Nd-Fe-B system rare earth magnets have the best characteristics of all magnets that have been developed so far, and their application in various industrial fields brings great economic profits.
Neodymium-iron alloy is a main material for production of Nd-Fe-B magnets.
The research team has established a system of producing Nd-Fe by rare earth fluoride-oxide molten salt electrolysis.
Compared to chloride electrolysis process, fluoride-oxide electrolysis process has good adaptability to raw materials and it enables production of various rare earth metals and alloys.
Fluoride-oxide electrolysis, a method by which the composition of electrolytes is not changed and neodymium oxide is periodically supplemented, makes possible continuous production without any limits of electrolysis time.
The Nd-Fe production process consists of electrolyte manufacturing process and electrolytic production process.
In the electrolyte manufacturing process, anhydrous neodymium fluoride is produced from neodymium chloride.
In the electrolytic production process, Nd-Fe alloy is produced in a graphite crucible with a pure iron electrode as a cathode and a carbon electrode as an anode.
Under electrolytic conditions, the current efficiency is 68~69%, the direct yield of neodymium is 92%, and the power consumption is 13.7 kW•h/kg.
The content of neodymium in the neodymium iron alloys produced is very high with more than 85%, and the non-rare earth content is very low, so that the alloy can be used for the production of magnets directly without undergoing a refining process.
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Jo Jul 15, 2023
A research team led by Kim Yong San, a researcher at the Faculty of Electrical Engineering, has developed a small wind power generation system capable of ensuring maximum efficiency in low wind speed regions.
For efficiency improvement, they applied average wind speed determination method based on left truncation Weibull distribution to the design of blades of a wind turbine. As a result, the average wind speed was determined to be 4.4m/s in the region with yearly average of 3m/s and on this basis the efficiency was improved by 13%.
The system consists of a three-blade horizontal axis propeller wind turbine, a three-phase permanent magnet generator, a control device, an inverter, load and so on.
Applying this method to small wind turbines usually used in low wind speed regions, they were able to produce more electrical power from the same amount of wind.
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Jo Jul 13, 2023
A research team led by Kim Kang Su, vice-dean of the Faculty of Shipbuilding and Ocean Engineering, has designed and constructed a multi-purpose ladder-dredger.
Several kinds of multi-purpose dredgers are being used all over the world for river and coast improvement, ecological environment protection and prevention of flood damage.
The dredger they have newly constructed works with several dressing machines and discharging equipment for different purposes ― a excavator bucket, a drum screen, a washer, a concentrator, discharging equipment, anchorage posts and elevators.
When the sands and gravels are dropped down from the bucket, they are separated individually while being washed by the water from a pump. The separated sands are transported into the concentrator and the gravels are conveyed to the ship by the belt conveyor.
The concentrator separates high density ores from the sands by using the jig. The separated sands are moved through the drain into the transfer tank and loaded on the ship by the bucket-type conveyor and the belt conveyor.
When working, the dredger holds its position and posture by 2 fore anchors and 1 aft anchor.
All the equipment is comprehensively controlled in the control room.
The multi-purpose ladder dredger will keep the environment cleaner for river improvement, thus contributing to the prevention of flood damage.
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Jo Jul 12, 2023
A research team led by Ho Kuk Chol, a researcher at the Nano Physics Engineering Institute, has made some achievements in their research into determination of catalyst synthesis conditions and cell operation parameters for preparation of ozonized water with dissolved ozone concentration of above 10 ppm, by using nanocomposite catalysts.
Electrode material for producing ozone by electrolyzing water is supposed to suppress oxygen generation by increasing oxygen overpotential and be stable for strong polarization in electrolytes. To date, many anode materials have been developed, including Pt, PbO2, SnO2, boron doped diamond (BDD). These catalysts have advantages and disadvantages in terms of ozone generation efficiency, service life and cost, among which ozone generation efficiency and low cost are considered to be the top priority in the case of sterilizing water used for preventive disinfection.
PbO2 is a catalyst material of significant importance in the technology of ozone generation by water electrolysis. Not only is it inexpensive and can provide high current density, but also it has the characteristics of higher current efficiency under the same electrolysis conditions than Pt.
They prepared a nanocomposite anode catalyst with high ozone generation efficiency by using PbO2 and analyzed its properties before determining the effect of factors on ozone production efficiency.
The nanocomposite catalysts for water electrolyzed ozone generation prove some economic effectiveness.
Although the lifetime is 1/3 of that of precious metal series catalysts, the total cost can be reduced by more than 80%, with only 5% of manufacturing cost.
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