Jo May 13, 2022
Kim Myong Il, a vice dean at the Faculty of Communications, has invented an indoor antenna for mobile communication.
Compared with previous antennas, this antenna has several advantages ― it ensures enough matching, gain and horizontal omni pattern in a wide band of frequencies; it is easy to feed, produce and assemble; it is light, good-looking and easy to install.
Consisting of a cone monopole, a double cone reflection panel, a curved plastic protection lid and coaxial feeding structure, the antenna assumes horizontal omni pattern in a wide range of frequency such as GSM, WCDMA, LTE, etc. With the gain of 3dBi, it can provide indoor mobile communication service in areas such as the underground of a building where mobile communication service cannot reach.
As a wide-range radiator, a cone monopole has top and bottom panels made of metal (Oblique angle is 25.5, radii are 12mm and 21mm respectively.), with an impedance of 50Ω and a wide radiation area. So it is of nearly omni directional pattern on the horizontal plane.
Vertical radiation can be controlled by a double cone reflection panel consisting of a primary cone reflection panel, a plain reflection panel, an upper cone reflection panel for coaxial feeding and it can bring a gain of 3dBi.
The inner conductor of a feeding coaxial cable is connected to the bottom panel and the outer conductor is linked to the reflection panel. The impedance of the antenna can be controlled by inserting an inclined line between the cone monopole and the reflection panel. Therefore, the impedance of the antenna remains constant in a wide frequency range. What is more, it is easy to install on the wall and it is covered tightly with a radome made of glass fiber plastic in order to prolong the life span and give a good-looking appearance.
In a wider frequency range(756~1 063/1 670~2 777MHz) than in the frequency range of former wire monopoles, the gain is 3.2dBi, which is 1.1dBi higher than former antennas (2.1dBi), so the service bound gets 1.4 times wider than before. The antenna is light, easy to install and meets aesthetic requirements.
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Jo May 11, 2022
Kim Ryul, a researcher at the Faculty of Electronics, has developed a new insulation bushing for a 10kV electric boiler that conforms to the operating conditions of the boiler and guarantees high reliability.
Unlike prior bushings of a cylindrical shape for a 3-phase 3kV electric boiler, a newly-developed one is of a conical shape, satisfies the operating conditions for a 10kV electric boiler and is more reliable and lighter. As its head has been changed into a ring type, they can increase yield, which means it can help reduce the level of environmental pollution and save raw and other materials
The new bushing is lighter by 0.7 times each, which means it has now become cheaper to make.
What is more, it is 2.4 times higher in dielectric strength, 3.3 times in working voltage, 1.25 times in output power, 2.7 times in 5-minute upkeep water pressure and 0.65 times lower in maximum current, which offers a scientific guarantee of the operating conditions and reliability of a 10kV electric boiler.
The yield has increased up to 93%.
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Jo May 6, 2022
Ssirum (Korean wrestling), part of the superior national heritage created and developed by the Korean people from ancient times, is a traditional sporting event where two people who grasp each other’s thigh bands compete to bring down the opponents onto the ground using their hands, legs and bodies.
Korean ssirum, registered as part of the intangible heritage of the World Heritage Committee of UNESCO, has a long history and tradition.
Korean Ssirum is said to have made a start in Ancient Korea and have been perfected in Koguryo.
Although several nations and countries including Mongolia and Japan did have similar strength events called ssirum, Koguryo ssirum had some unique features ― wrestlers wearing heavy cloth bands around either thighs and no garments on their upper bodies competed in strength with their chins tucked on the opponents’ shoulders in bare feet; ssirum was well organized according to strict rules; wrestlers were trained to be professional.
Unlike Koguryo ssirum, however, Mongolian ssirum allowed wrestlers to wear shoes and upper garments similar to leather waistcoats.
Meanwhile, influenced by Korean ssirum, the Japanese did ssirum with thigh bands, bare upper body and bare feet. This explains Japanese ssirum originated from Korean ssirum.
This assertion is also supported by the figures discovered in Inbe Hachimanyama Tomb (around 6th century) situated on the basin of the Ginogawa River in Wakayama Prefecture, Japan.
Figure 10 of strong man erected in the east of the group of tombs bears a close resemblance to Koguryo ssirum wrestlers.
It proves that Japanese ssirum was not invented and developed in Japan itself, but introduced from Koguryo.
Such information is also found in “Japanese History” and other Japanese historical records.
In a word, Korean ssirum, which was developed in Ancient Korea and perfected in Koguryo, was disseminated through the neighbouring countries of the same blood Paekje, Silla and Kaya to the Japanese archipelago, exerting a significant influence upon the cultural development of the island country.
Indeed, the time-honoured and superior culture and tradition created by the Korean nation from olden times was introduced into other countries, thus leaving an indelible mark in their history of cultural development.
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Jo May 3, 2022
The contests came to an end on April 25, 2022.
The first contest, which was held on April 8 to 11, drew 20 000-odd contestants from tens of countries and regions including our country, China and India. More than 130 participants competed in Division 1, over 600 in Division 2, over 4 600 in Division 3 and over 15 500 in Division 4. Division 1 set forth 5 problems, none of which were challenge problems.
A total of 27 contestants won the first place in Division 1 ― 19 from the DPRK, 3 from China, 2 from India, 2 from Japan and 1 from the US.
10 out of the 19 winners of our country are students at Kim Chaek University of Technology.
As much as 70.37% of the world winners are from the DPRK, and 37.037% are from KUT. KUT students add up to 52.63% of the 19 DPRK winners.
In the meantime, a student from KUT took the first place in Division 2.
Several KUT students who were absent from the Codechef March Long Challenge due to the national coding challenge held in the same period took part in this contest, which bestowed on KUT the honour of having many winners.
The second contest went on from 22 to 25. 18 000-odd contestants from tens of countries and regions including our country, China and India took part. Over 70 contestants competed in Division 1, more than 900 in Division 2, over 3 300 in Division 3 and over 14 000 in Division 4.
4 from our country and 1 from Japan made a total of 5 winners in Division 1.
Half the 4 DPRK winners are students from Kim Chaek University of Technology.
Our country and KUT make up 80% and 40% of the world winners, respectively.
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Jo May 2, 2022
Among the national instruments reflective of national emotion and aesthetic sense that have undergone constant development by the Korean nation is a pipe with a long history.
A pipe with which you make a sound by blowing at one end across a hollow rod with several holes on it is one of the widely-used woodwind instruments.
Having been used for their emotional life by our nation from the earliest period, it served as a popular instrument since it is portable and simple in type and it produces an elegant and clear tone.
Since primitive times Korean people have played pipes made of different materials like animal bones, leaves or stems of trees, reeds, etc.
The Bronze Age cultural stratum of the Sopho Port Site in Rason City was unearthed with a bone pipe recognized as dating from the 3rd millennium B.C. It was made of the bone of a bird’s leg and drilled with 10 holes, which is just enough to demonstrate that Korean nation is a wise and talented nation that made instruments for their cultural life in the earliest days in the world, and that a pipe has a time-honoured tradition.
In Ancient Korea, not only soft-toned pipes made of animal bones and bamboos but also others of a pipe kind such as tophy (a roll of a leaf of a peach tree), ka (a simple kind of a single tone with no holes on the side), etc. made of a variety of materials were devised and used as musical and signal instruments.
In the period of Three Kingdoms, Koryo and Feudal Joson Dynasty, various kinds of pipes with different tone colours and ranges were also made to improve the descriptive power of instrumental music and these pipes took charge of main melodies of music.
Besides, pipes were played in every single piece of folk instrumental music and popular with people of all levels of society over a long period in the Middle Ages, and every part of the country has had fine customs of children playing on willow pipes in early spring.
In summary, a pipe is one of the typical national instruments that have been penetrated deep into the life of the Korean people and have made a great contribution to the development of national music while dominating musical performances.
Today under the scrupulous care of the Party and state, which value the traditions of our nation, pipes are on the way of progress forming the main part of national instruments.
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Jo Apr 29, 2022
In general, knowledge on the mechanical properties of a rock mass is a prerequisite for the numerical simulation and the design of the underground structure, opening-up of mineral deposits and mining processes.
Since the early 1990s, many scholars have proposed a variety of methods to determine the strength and deformation parameters of a rock mass using geological strength index (GSI). The standard GSI chart considers qualitatively the surface condition and blockness of a rock mass, and it is used to estimate values between 0 and 100 representing the overall geotechnical quality of the rock mass. The best outcomes can be achieved only by the collaboration between experienced engineering geologists and geotechnical engineers.
To quantitatively determine the GSI, you have to detect the joints in two-dimensional (2D) photographs of a rock mass surface using image processing technology, then determine the fractal dimension, and finally predict the GSI using artificial neural network (ANN).
The detailed steps for joint detection on the rock mass surface are as follows.
Step 1: Converting the color image of a rock mass into a black and white one
Step 2: Smoothing and sharpening
Step 3: Binary encoding
Step 4: Noise removal
Step 5: Detection of the joints
The fractal dimension of a 2D rock mass surface can be calculated with previous research findings.
A 3-layer BP ANN is used for predicting the GSI of the surface of a jointed rock mass.
On the basis of the GSI chart, an ANN model is established, in which the input neurons are the fractal dimension and surface condition index (i.e. roughness and weathering condition), and the output neuron is a GSI value. And the number of neurons of a hidden layer is first set to three and it is finally determined via learning procedure to establish the most effective ANN structure.
In this way, the GSI of a jointed rock mass can be determined quantitatively and objectively by the interface, coded by using built-in tools of MATLAB 7.0, such as image processing, fractal analysis and ANN.
The details of this can be found in the essay, “Determination of geological strength index of a jointed rock mass based on image processing” by Hong Kun Ui, dean of the Faculty of Mining Engineering, presented to the SCI Journal “Journal of Rock Mechanics and Geotechnical Engineering”.
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