Jo Aug 13, 2022
A research group led by Kim Sun Il, a researcher at the Faculty of Metal Engineering, has introduced his invention, an intelligent laser bird repeller with a deep neural network.
By comparison with existing repellers, the system of this bird repeller, whose design and database are based on sufficient experimental research into birds in various kinds and sizes, is programmed to undergo constant update, thus ensuring greater efficiency in bird detection and classification.
It detects birds by means of a camera, decides the mode of attack suitable for the detection results and sends signals to the laser driver device before attacking.
It consists of three parts ― a laser attack unit combined with an outdoor monitoring camera, a laser driver unit and a computer processing unit.
The laser attack unit consisting of the bunch of green (532nm), blue (420nm) and red (650nm) lasers of 1W is embedded in the outdoor monitoring camera. Once an image is sent to the computer, it detects and tracks the bird and sends a signal to the bird repeller device using artifical intelligence technology. This device emanates laser light driver signals according to the kind and size of birds and the intensity of light dependent on the weather change.
The interface consists of monitor, statistics, log, main setting, etc.
With 98.7% detection rate and 95.3% repelling rate, the fully automated system is applicable to all places including farms, fish farms, orchards and airfields that are exposed to the damage by birds.
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Jo Aug 9, 2022
Yu Chung Sim, a lecturer at the Faculty of Applied Mathematics, has studied a method to increase the convergent speed of global optimization.
The filled function method is an effective method to get the global optimization solution to multi-dimensional optimization problems.
One of the major problems to be solved in the search for a global optimization solution to multi-dimensional optimization problems is how to escape from the given local minima into a better one.
To solve this problem, a number of methods including Orbit method and Tunneling method have been investigated. Among them the filled function method has been admitted as an effective one and thus, it has been undergoing further study.
The filled function method was first applied to unconstrained nonlinear programming problems, followed by constrained nonlinear programming problems, non-smooth optimization problems and discrete optimization problems.
At present, in order to improve the effectiveness of the global optimization solution search algorithm using a filled function, many scientists have been looking for methods to combine various methods including the filter method and the interior point method with the filled function method.
The main problem of the filled function method is how to construct an auxiliary function called filled function at the given local minima of the objective function obtained from every repetition of the algorithm.
For this, filled functions with one parameter and those with two parameters were proposed, but they are difficult to control when they have more parameters
Recently, a new filled function method that skips the process where they used to get better minima by minimizing an objective function from the local minima of the filled function in the prior algorithms is being applied to continuous optimization problems.
As seen above, you can see that the filled function method can be applied to the global optimization problems arising in practice if we introduce filled functions with few parameters in the continuous optimization problems as well as discrete optimization problems, non-convex optimization problems and non-smooth optimization problems.
Therefore, she has proposed a new filled function that comes from the idea that an objective function and a filled function have the same stationary points and applied it to finding a global minimum solution to constrained nonlinear programming.
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Jo Aug 5, 2022
Ri Yong Ho, a section head at the Faculty of Heat Engineering, has been working hard to make further achievements since he developed a speed control device of a turbo coupling which is widely used in the speed change coupling of a large rotating machine.
The device consists of a turbo coupling, a speed control instrument and a distributed control system.
The fluid coupling, a power transfer device of a rotating machine, can control speed, has a wide control range and has good control characteristics. With a good power transfer characteristic, it can raise energy efficiency.
To use the turbo coupling’s speed control function, we must get a correct understanding of the turbo coupling’s working principle before designing and making a speed control instrument based on it.
The oil system of a turbo coupling consists of a lubricating oil system and a hydraulic oil system. The lubricating oil system functions as a supplier to provide lubricating oil to the coupling’s gears and medals while the hydraulic oil system controls rotating speed. The deeper the coupling is submerged in the oil, the larger the viscosity of oil gets and the faster the output rotating speed gets. The depth of the oil depends on the height of the dipper pipe.
The flow control piston controls oil discharge which passes through the turbo coupling.
The depth of the dipper pipe piston controls the rotating speed; the flow control piston controls the amount of hydraulic oil discharge to allow the turbo coupling to work.
The speed control instrument consists of a rotating motor that converts the control system’s command into the rotation angle, and cam accessories. The rotating motor receives 4~20mA current signals from the control system and in proportion to it, rotates the axis in the range of 0~150°, feeds it back to the control system in proportion to the rotated angle.
Two cams are installed on the axis of the conversion device, and they press on the fluid control piston and the dipper pipe piston individually according to the rotated angle. The main components of the conversion device are the two cams.
Based on the piston’s working principle, the working cycle, the size and installation conditions of the speed control instrument, the cam’s curve radii are decided as follows.
The fluid control cam’s radius: min = 96mm, max =115mm.
The dipper pipe cam’s radius: min = 96mm, max =117mm.
If the above-mentioned turbo coupling is installed between the main feed pump and the motor of the 210MW boiler-turbine block, it controls the rotating speed of the feed pump, which enables to control the output water pressure and the drum level of the boiler.
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Jo Aug 3, 2022
A research group led by Choe Yong Chol, a researcher at the Faculty of Mining Engineering, has been employing his new method of reducing the amount of harmful explosion gas by using vermiculite and acidic deposits of mine water.
Introducing this technology, you can increase the power of explosion much higher than before thanks to the increase in the work ability resulted from the evaporation of combined water in vermiculite as well as the increase in brisance resulted from the increase in explosive density. At the same time, you can reduce the emission of harmful explosion gas such as CO and NOx by adsorption of expanded vermiculite, absorption of water separated from vermiculite and oxidation of metallic oxides in vermiculite at high temperature of explosion.
This method has two stages; manufacturing stage where vermiculite that passed through crushing, separating and distributing processes and acidic deposits of mine water are mixed, and application stage where they are admixed with explosives.
Explosive additives are made with vermiculite of 0.1mm~1.5mm in granulation size and acidic deposits of mine water less than 0.05mm in granulation size in the proportion 3:1. This mixture and Expanded Ammonium Nitrate Explosives are mixed evenly in a ratio of one to five and put into blasting cartridges before use.
Most of the acidic deposits of mine water consist of ferric hydroxide(Fe(OH)3) and basic ferric sulphate(Fe(OH)SO4). In vermiculite, some metallic oxides such as ferric oxide make up about 5.5%, which is less than those contained in acidic deposits of mine water. Trihydric ferric salt and ferric oxides serve as oxidizers that oxidize CO and NO in explosion gas to CO2 and NO2 respectively.
Vermiculite contains about 15% of interformational water which is not changed between micaceous layers at low temperatures but converted into water vapor at over hundreds of degrees. This interformational water removes harmful gases by absorbing soluble gases like NO2, N2O3, N2O4, etc. produced from explosive reactions and from oxidation by trihydric ferric constituents in the additives.
Vermiculite has a strong cation exchange ability. Its cation exchange capacity and base absorption capacity increases by 1.5 times at high temperatures. Thus, at high explosion temperatures vermiculites are expanded and the absorption ability for harmful explosion gas is further increased.
When explosives are mixed with vermiculites and acidic deposits of mine water that are heavier than constituents of explosives, the charge density of explosives increases. Consequently, the detonation velocity and pressure increase and the dynamic explosion power of explosives gets higher.
Vermiculite has a maximum of 18% of interformational and combined waters, which are changed into water vapour at the moment of explosion and expanded thousands of times in volume. It results in a considerable increase in the volume of explosion gas and in the explosion pressure of explosives, which leads to the increase in the static power and blast effects.
If this additive(vermiculit and acidic deposit of mine water) makes up 20% in explosives, removal rate for CO and NOx gases can be more than 93% and 85% respectively. The explosion power of explosives remains similar to or gets higher than before.
With the introduction of this method to all kinds of blasting operations such as driving, you can save a considerable amount of explosives and make a contribution to protecting the environment and improving working conditions by reducing the emission of harmful explosion gas.
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Jo Jul 26, 2022
Formal Concept Analysis (FCA) is considered to be a major formalism for knowledge extraction, reduction, representation and analysis. The core of the mathematical theory of FCA is formal concept lattice.
Determination and description problems on the formal concept lattice are basic ones of FCA. The determination problem is “How can one determine the concept lattice of a given context?” and the description problem is “How can one describe the concept lattice of a given context?”. The most communicative description of the concept lattice is known to be given by Hasse diagrams. However, it is difficult for any information retrieval software to autonomously understand the hierarchy of the concepts from Hasse diagrams. If the hierarchy of the concept lattice is described with a matrix corresponding to Hasse diagrams, any software will be able to autonomously understand the hierarchy of the concepts by the hierarchy-matrix.
In order to obtain such matrix, matrix-correspondence of finite topological spaces obtained by the introduction of Scott topology into the finite concept lattices must be employed and then a new hierarchy-matrix describing the hierarchy of the concept lattice be generated. This idea is based on the matrix-correspondence of finite topological spaces and the fact that Scott topology base is a collection of upper sets of every element. This hierarchy-matrix embodies all the information of the Hasse diagram and is well adapted for use to software.
Pak Chol Hong, a researcher at the Faculty of Applied Mathematics, has proposed a method for generating a new hierarchy-matrix, estimating the connectivity of concepts by the hierarchy-matrix, describing the Hasse diagram via a hierarchy-matrix and generating the hierarchy-matrix via the Hasse diagram in a given finite concept lattice.
The results can also be discussed in universal lattices. If the description of the concept lattices via the hierarchy-matrix is linked up with the determination of the concept lattices, then the formal concept analysis will be used more effectively in several areas of information retrieval, knowledge mining and database management.
Meanwhile, he has proposed that the finite concept lattice is an algebraic lattice and a topological lattice with respect to the Scott topology and the category of finite concept lattices as objects and monotonic mappings as morphisms. These results seem helpful to categorical research into FCA.
More information about this is in his paper “Describing hierarchy of concept lattice by using matrix” presented to SCI Journal “Information Sciences”.
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Jo Jul 24, 2022
Jang Ui Jun, a researcher at the Faculty of Earth Science and Technology, has developed a plasma water treatment device, an experimental device for education and research, which enables experiments for improving the quality of groundwater and surface water to be conducted in combination with laboratory conditions and field characteristics, and verified its utility.
In general, water treatment devices for improving the quality of groundwater or surface water include chlorine sterilizers, various kinds of filters such as activated carbon filters, UV disinfecters, ozone sterilizers and plasma sterilizers.
A plasma water treatment device, one of advanced water treatment devices, is able to overcome the limitations of the above-mentioned water treatment devices and conduct sterilization and water treatment comprehensively and efficiently by means of active chemical species as well as ultraviolet and ozone.
It consists of a power supply unit for geneartion of pulsed high voltage, a plasma reactor, a water sample tank and a water control valve and a tank for treated water.
Using this plasma water treatment device, we can do experiments the aim of which is to reduce the contents of various water quality indicators contained in contaminated surface water or groundwater, especially some elements such as Fe2+, to remove bacteria including Escherichia coli, and to improve water quality.
This device, compared to the aeration method, helps increase the rate of oxidation of Fe2+ ions in water by more than 2.5 times and raise recognition effect by providing visual effects.
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