Jo Feb 11, 2023
“Samgukyusa” (History of the Three Kingdoms), together with “Samguksagi” (Chronicles of the Three Kingdoms), is known as the oldest historical book of all existing national classical legacies.
It was written by a Buddhist monk Il Yon (1206―1289) at the end of the thirteenth century. The histories of Koryo and other ancient states in our country with the main focus on the history of the period of the Three Kingdoms (Koguryo, Paekje and Silla), and the episodes of well-known monks are recorded in the style of unofficial history.
It is in five volumes and nine parts.
At the beginning of Volume 1 is “Wangryok”, a chronological table of dynasties of the Three Kingdoms and Karakguk. The rest of Volume 1, and Volume 2 have 36 articles from every king’s ruling period of Silla and other states after Ancient Korea and 23 articles from Later Silla, Later Paekje and Karakguk.
Volume 3 to Volume 5 mainly deal with Buddhist monks who contributed to the spread of Buddhism, other celebrated monks, towers, Buddhist statues and bells erected on famous mountains and at temples.
The book also contains poems and songs including 14 pieces of old Korean folksongs (native songs pronounced in Chinese characters), tales, history of old names of places, buildings and ways of life and other valuable data in every field including literature, fine art, sculpture, language, geography, folk customs, etc.
Therefore, it reveals some historical limitations. However, for its rich and precious content that cannot be found in other historical books, it is indispensable for research into the history and culture of our country.
Kim Chol Ryong, researcher at the Academy of Social Sciences
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Jo Feb 9, 2023
It is of great importance to make a proper classification of underwater sediments for protecting the ecological environment and dredging materials such as sand or gravel, mud, etc. in rivers or oceans.
Ri Un Song, a section head at the Faculty of Shipbuilding and Ocean Engineering, has newly defined some characteristic parameters and established Artificial Neural Network (ANN) with these parameters as input layers. By doing so, he has managed to find a way to raise the accuracy of acoustic sediment classification on rough riverbeds.
The neurons of input layers used include the newly-defined roughness and monotonic decreasingness of the tail potion of the first echo signal as well as the roughness index and hardness index usually employed in Rox Ann and QTCView.
The proposed method has raised the accuracy of acoustic classification of sediments in the water areas with rough floors to 95%.
It is now in effective use for search for gravels and sand by dredging vessels on riverbeds, and for classification of sediments accumulated on the dams of floodgates, tidelands, etc.
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Jo Feb 8, 2023
Ullim Falls is situated six kilometres east of Tonghung-ri, Chonnae County, Kangwon Province, and about ten kilometres north-east of Ryongpho Revolutionary Site in Poptong County.
75 metres in height, it is one of the most famous waterfalls in our country.
The name Ullim (literally echo) Falls means that the sound of the magnificent waterfall resounds far away across the whole valley.
Around the falls rise high mountain peaks one after another, whose feet are sword-shaped cliffs.
There are several facilities such as a sightseeing road, a bridge, an outdoor eating place, a car park, etc.
The magnificent view of Ullim Falls adds ardent love for the beautiful landscape of our motherland.
Sin Kwang Il, researcher at the Academy of Social Sciences
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Jo Feb 7, 2023
A research team led by Sin Jung Sok, a researcher at the Faculty of Earth Science and Technology, has developed an ultrasonic mixer to improve the combustibility of heavy oil burners by ultrasonic waves generated by the steam in a tubular furnace.
This technology can help to make ultrasonic waves by high pressure steam to change the carbon chain structure of heavy oil whose relative viscosity is over 200 and to decrease the viscosity. It leads to the improvement of spraying characteristics of burners and to the sharp reduction of consumption of heavy oil necessary for oil processing.
The ultrasonic mixer has 1st ultrasonic wave generator, mixing unit of heavy oil ― steam, 2nd ultrasonic wave generator, spraying unit, etc.
In the 1st ultrasonic wave generator, high pressure steam that passes through the jet orifice, resonator and reflector can make ultrasonic waves of 14~17kHz, which enter the heavy oil ― steam distributor.
In the heavy oil ― steam mixing unit, the heavy oil coming in four tangential directions through the heavy oil ― steam distributor is mixed with steam. Then, the mixed liquid is sprayed. At this time, the chain structure of the heavy oil is destroyed primarily by the ultrasonic waves.
When the sprayed liquid causes the 2nd resonance while passing the resonator of the 2nd ultrasonic wave generator, most of the heavy oil particles are pulverized to be smaller than 20㎛. The purpose of the 2nd ultrasonic wave generation is to break up the liquid particles mixed through the heavy oil ― steam distributor into smaller ones.
In the spraying unit, heavy oil and steam are mixed evenly and sprayed through 8 holes. The size of about 90% of heavy oil particles is within the range of 10~20㎛.
The intensity of ultrasonic wave is 200dB at the 1st ultrasonic wave generator and 220dB at the 2nd one.
If the size of heavy oil particles is below 30㎛, the combustion efficiency of heavy oil in tubular furnaces reaches higher than 95%, which equals the case of combustion of heavy oil whose relative viscosity is 100.
The introduction of this device to tubular furnaces for oil processing can lower the flue temperature by 15~20℃ and reduce the consumption rate of oil. It can also improve the spraying quality of liquid and raise the combustion efficiency in the burners of tubular furnaces.
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Jo Feb 6, 2023
Washing holes is a very difficult and complex process that cannot be seen, so it must be proved experimentally.
Therefore, Han Chang Son, a researcher at the Faculty of Earth Science and Technology, employs a simulation device for flow of drilling fluid in his subject “Drilling fluid” to develop students’ creative thinking faculties by presenting principles and vivid images on washing processes.
The simulation device consists of hole models, a pipe rotary device, a cuttings supply device, a pump, a flow route, a fluid box and a control button.
As the simulation device aims to simulate the flow of drilling fluid and the movement of cuttings, he built two hole models in conformity with actual drilling conditions: Model 1 formed of high intensity rock and Model 2 formed of low intensity rock.
In the lesson, he puts the device in operation to show the students the processes of pressurized fluid supply through the rotary pipe and of cuttings conveyance along the annulus, the difference in the rising speed in the sections of various hole diameters and the process of accumulation of cuttings in widened drilling holes.
With the help of the device, the students are able to realize the following things: Cuttings are not transported out of drilling holes but move in their positions with spiral rotation movement due to pipe revolution. The higher the number of pipe revolution and the viscosity of drilling mud, the stronger the spiral rotation movement gets, so transportation of cuttings really goes well. In the formation with weak rock, hole diameters become wider because of erosion, which leads to the slowdown of the flow velocity and the accumulation of cuttings.
They are also able to find a way to improve drilling fluid processing methods.
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Jo Feb 3, 2023
The monument to Mausoleum of King Kwanggaetho is a stone monument erected in 414 by his son, King Jangsu (25th king), in praise of the meritorious deeds of King Kwanggaetho, 24th king of Koguryo (ruling period: ３9１－４１２). The mausoleum is located 6 kilometres north-east of Kungnae Walled City (Jian City, Jilin Province), the second capital of Koguryo.
The monument is made up of a body stone and a stone pedestal. On the four sides of the smoothly processed body are drawn lines vertically and horizontally where letters are inscribed clearly. Only 1 530 of the letters written vertically in 44 lines are recognizable.
The words on the monument are largely divided into three parts.
The first part covers from the legend of the founder of Koguryo to the enthronement and demise of King Kwanggaetho. The second part deals in detail with the meritorious deeds of extending the territory of Koguryo performed by King Kwanggaetho. The third part regulates the number limit of mausoleum guards and the rules they had to follow.
The monument reflects the struggle and desire of Koguryo people for the unification of the three kingdoms. It also has a lot of valuable information that is not found in documentary records of political, social and economic situations of Koguryo, class relations, and relations with Silla, Paekje and Japan, etc. of that time.
The letters are written in a peculiar font, Yeso. The majestic and vigorous font demonstrates the lively and vigorous spirit of Koguryo people.
The monument gives an account of the vastness of the territory and the might of Koguryo, the eastern power. For its magnificence (longest and biggest of all grave stones made by our ancestors) and rich content, it proves to be precious cultural inheritance of our nation and important material for historical research.
Kim Son Yong, researcher at the Academy of Social Sciences
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