Jo Dec 30, 2022
Ozone is the second to fluorine in oxidation and sterilization power and it reacts with organic and inorganic materials very well. In addition, it leaves no remainders harmful to the environment. Thus, it has been used not only for food containers but also in fish farming, medical and chemical industries etc. Recently, positive attempts are being made to use it to prevent various infectious diseases.
Accurate measurement of ozone concentration is important for its effective use. One of the most cost-effective measurements is using detector paper.
The ozone detector paper for determining concentration of ozone in the atmosphere has already been developed. When indigo carmine reacts with ozone, the paper turns from blue to white. This principle is used to measure albedo for determination of ozone concentration. The measurement range of the paper is 0~400ppb and the CT value is 0~400ppb×h. The unit of time is hour. It is impossible to precisely measure concentration over the range because the detector paper immediately turns into white completely. The response time of the detector paper is over 30 minutes.
However, research into dissolved ozone detector paper has not been conducted.
Kim Yong Ok, a researcher at the Faculty of Applied Chemistry, has developed detector paper for dissolved ozone.
The dissolved ozone reacts with KI to produce iodine, which then reacts with starch to turn the paper blue. This means that the paper turns from white to blue according to the ozone concentration. Thus, the chromaticity of the paper helps determine concentration of dissolved ozone.
This paper guarantees precise and quick measurement for up to 8ppm of concentration of ozone within a short time of 30~40s.
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Jo Dec 28, 2022
High-efficiency electric drive systems claim not only optimally designed electric machines but also efficiency-oriented control strategies.
Taking machines and drives into synergetic consideration, Jong Hak Chol, a section head at the Faculty of Electrical Engineering, has proposed a fresh particle crowd optimization (FPCO) of efficiency-oriented control algorithm called maximum outer torque per ampere (MOPA) control and maximum efficiency per ampere (MEPA) control, aiming to maximize the efficiency of interior permanent magnet synchronous machines in operation.
Differently from conventional id = 0 or maximum torque per ampere control, MOPA and MEPA fully consider the cross effect Core loss, iron loss, supplementary loss and mechanical loss.
In order to identify the accuracy of the efficiency-oriented control algorithm, he built an efficiency-oriented controlled system based on FPCO using nonsingular terminal sliding (NTS) controller, and on the basis of this, he inspected the stabilization of current trajectory and the voltage vector from simulation and testing. After that, he verified the higher effectiveness of MOPA and MEPA through the operation experiment of IPMSM whose capacity is 82 kW.
You can find more information about it in his paper “Fresh particle crowd optimization of efficiency-oriented control in interior permanent magnet synchronous motor during operation” published in the SCI Journal “International journal of power and energy conversion”.
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Jo Dec 27, 2022
Every country has their symbolic animals that reflect the history and culture, excellent dispositions and extraordinary abilities of their people. Among them is a dog.
Phungsan Dog is a native breed of Korea that has left an indelible mark in the history of our nation for thousands of years. It has been tamed for ages by our ancestors in severe natural environments of the northern uplands where there were a large number of beasts such as a tiger, a bear, a wild boar, a wolf, etc.
Well adapted to the topography and climate of the mountainous forest areas in our country, the dog has features of a typical hunting dog. It is famous for its cleverness, persistence, bravery and swiftness. Though this dog is of smooth nature and quite obedient to its keeper at ordinary times, it shows a strong fighting spirit and bravery at the time of hunting and it never gives a fight up. Full of vitality, it is resistant to the cold and diseases.
It was registered as a state natural monument in April, Juche 45 (1956) thanks to the state measure taken by President
When visiting Ryanggang Province in May, Juche 47(1958), the President said that Phungsan Dog thoroughbred is a very good breed, underscoring the need to survey its thoroughbred.
Chairman
On November 7, Juche 103(2014), the respected Comrade
Today, Phungsan Dog is widely known as a national dog that symbolizes the spirit of properous Juche Korea and as a world’s famous dog.
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Jo Dec 25, 2022
Time-dependent deformations of rock are important factors for the design and construction of tunnels in the rock masses with time-dependent strength and deformation properties. Therefore, determination of the displacement and the stable time of tunnels is an indispensable task in geotechnical engineering, especially the design and construction of underground structures.
However, in some types of rock masses, tunnel displacement may increase for months or years after excavation owing to the rheological behavior of the surrounding rock masses, which greatly influences the selection of an initial tunnel support system, excavation layout, and determination of its load-carrying capacity.
Therefore, Han Un Chol, a researcher at the Science Engineering Institute, has made it possible to predict the final displacement of rock mass surrounding a tunnel, which is gradually stabilized in the shape of an S-type saturated curve by using the improved nonequidistant grey Verhulst model (INGVM) with Fourier series.
The traditional non-equidistance grey model (NGM(1,1)) and non-equidistance grey Verhulst model (NGVM) were compared to examine the feasibility of INGVM application. He only used the monitored displacements during excavation to predict the final displacement and stable time of the tunnel excabated in time-dependent rock mass.
The results showed that the proposed model was highly accurate and adaptable.
The details of this are carried in his paper “Prediction of Final Displacement of Tunnels in Time-Dependent Rock Mass Based on the Nonequidistant Grey Verhulst Model” published in the SCI Journal “Mathematical Problems in Engineering”.
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Jo Dec 24, 2022
The Korean people, who have loved cleanliness from ancient times, invented methods of making and altering national clothes suited to their physiques and hobbies in the course of creative labor. Constantly developing them, they have been proud of being dressed in neat clothes.
While washing their clothes, our people discovered effective washing methods to wash dirt away in consideration of the material for clothes. Laundry usually went through primary washing, main washing and boiling before being rinsed and dried. In the primary washing, the first step in the washing, laundry is dipped in warm water for a light rub. It was mainly for heavily soiled laundry such as the inside of quilts. In the main washing, detergents are applied to the primarily washed ones before rubbing, clubbing or stamping. Due attention should be paid to the washing of silk fabric or velvet that are widely used for Korean clothes.
When ironing velvet, it should be held up from the floor, with its naps facing downwards.
Korean clothes should be carefully stored according to the seasons. Neatly folded clothes should be placed layer upon layer in a drawer: those for the present season on the top, those for the next season under them and those for the last season on the bottom. Those for a long time of storage need special care. For example, Korean jackets are placed with their right and left skirts aligned before the breast-ties are brought together, and then they are folded on the shorter breast-tie. The sleeves are folded on the armpit line. The skirt trimly folded in five to six folds is folded in half length. It is a good idea to hang skirts on a hanger.
It is important to be well aware of the methods of washing and keeping Korean clothes and to get dressed culturally.
Kang Hyon Sim, researcher at the Academy of Social Sciences
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Jo Dec 23, 2022
Ozone is one of the strongest oxidizers and disinfectants, and it does not leave any residual toxin as it is decomposed into oxygen. That is why it has been widely used in domestic and industrial areas such as disinfection of drinking water and air, wastewater treatment, pulp bleaching, food processing, decolorization and deodorization.
A research team led by Kim Jong Guk, a researcher at the Nano Physics Engineering Institute, has developed enamel ozone tubes and different types of DBD ozone generators. The most effective and practical one of all ozone generation methods is dielectic barrier discharge (DBD), which generates non-thermal equilibrium plasma.
A DBD ozone generator consists of an ozone tube and high-frequency high-voltage power supply. The ozone tube has an enameled steel tube as an internal electrode and a stainless steel tube as an external electrode. It shows stronger resistance to thermal shock and better heat dissipation than glass or ceramic material.
Addition of nano-powders as mill additive increases adhesive strength, dielectric constant and dielectric strength, which ensures a long lifespan of the generator and produces high efficiency of ozone generation. Water cooling for internal and external electrodes effectively prevents temperature rise when the ozone tube discharges, thus ensuring safe operation and high ozone concentration output. By using high-frequency power supply and intelligent control system, ozone output can be changed on demand.
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