Jo Sep 7, 2022
Tug-of-war is a folk game in which two teams pull at opposite ends of a long rope until one team drags the other over a line on the ground.
From ancient times our people with strong cohesion enjoyed doing tug-of-war that demonstrated communal might involving a lot of people.
Tug-of-war came into being through creative labour of mankind for survival. Whenever they needed to pull or drag up something in remote primitive times, our ancestors used to fasten ropes to them. This turned into a game little by little and eventually became tug-of-war, a competitive sport.
According to historical records, tug-of-war was usually done by peasants, especially in areas with a high proportion of paddy farming.
“Rimhaphilgi” (19th century) wrote that tug-of-war was already popular in the period of Three Kingdoms ― Koguryo, Paekje and Silla.
It became even more popular later in the period of Koryo and feudal Joson Dynasty. “Tongguksesigi”, “Hwagyejip”, “Tonggukyojisungram”, “Thamraji” and other historical books containing contemporary historical records give details of tug-of-war at that time.
Present-day tug-of-war is a little different in the ways of playing and ropes.
First, the thickness and length of a rope were altered to be convenient. After the national liberation, the thickness and length were fixed at 4~5cm and 20～30m each.
Next, unlike the past tug-of-war with main focus on strength only, the teams with tens of prearranged players have to pull the rope over one metre first to be the winner.
That is how tug-of-war was able to develop into a popular folk game in which many people can highly display the collectivist spirit of pooling their strength and wisdom, and players as well as spectators can enjoy themselves anywhere amidst tension, cheerfulness and laughter.
Im Sung Bin, section head at the Academy of Social Sciences
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Jo Sep 5, 2022
“Genetic algorithm” is one of the optimization techniques whereby the principles of genetics and evolution of living organisms are mathematically modeled and global optimization problems are solved based on them.
In the past, teaching genetic algorithms mainly focused on mathematical basis, principles and algorithmic description, and so it revealed that students had difficulty in selecting the best one of all different methods used to solve a problem.
To solve this problem, Kang Kum Sik, a lecturer at the Faculty of Applied Mathematics, let his students to write genetic algorithms and compare and analyse them.
Firstly, he encouraged the students to decide by themselves which methods are the best among different selection methods, crossover methods, and mutation methods used in each genetic algorithm, thereby enhancing their analytical and practical abilities.
Secondly, he led the students to synthesize the relationship of each genetic algorithm and find a genetic algorithm best suited for solving real-world problems, thus raising their synthesizing and systemizing ability and the creative ability of finding optimal solutions.
That is how students came to fully understand what they learn in both theoretical and programmatic ways, and acquire methods of finding optimal solutions while solving practical problems.
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Jo Sep 2, 2022
Yut game is a folk game in which players compete to be the first to move all their pieces to the finish position by throwing four yut sticks and making moves on the board as indicated by the sides of sticks.
Devised by the resourcefulness and talent of our people and played on several occasions including the lunar New Year’s Day, yut game is a time-honoured folk game peculiar to the Korean nation.
The game was invented in ancient times based on the principles of natural and social phenomena.
On the yut board is drawn a figure representing the principles of movements in the universe. According to historical records such as “Junggyongji” (1649) and “Ojuyonmunjangjonsango” (mid-19th century), the position in the middle of the board with a total of 29 signifies the Pole Star while other 28 positions around it represent the 28 constellations studded around the ecliptic. The routes on the board, on the other hand, reflect the law of change of four seasons. The shortest route (round through 11 points) stands for the winter solstice with shortest hours of daylight, the two routes through the diagonal paths for the spring equinox and the autumnal equinox with equal hours of daylight each, and the longest route for the summer solstice with longest hours of daylight.
The four sticks for throwing reflect four directions ― north, south, east and west.
The names of moves also reflect ancient social systems and customs. Not only the titles of ancient government positions Joga, Kuga, Uga, Maga, etc. but also the size and speed of domestic animals widely kept in those days were used to make the names of moves. For instance, the names “To”, “Kae”, “Kol”, “Yut”(Shung) and “Mo” mean “pig”, “dog”, “sheep”, “ox” and “horse” respectively. As they believed that oxen played the most important part in farming, they called this yut game.
All these imply that yut game originated from the small desire of ancient people who wanted to be successful and to travel all around the world on domestic animals to their hearts’ content.
This ancient game was carried forward and developed as a folk game peculiar to our nation in the period of Three Kingdoms (Koguryo, Paekje and Silla), Palhae and Later Silla and it was widely introduced into other countries, too.
At present, some newly devised ways of playing help players develop their intellectual faculties and have a good time. The number of pieces has now increased from four to ten, which means the first one to move all the 10 pieces is the winner. “Huto” (one step back) and “Tuhuto” (two steps back) and some other rules like the need to have one extra move before the finish point are now adopted, which makes it even more entertaining.
Today yut game is enjoyed at industrial establishments and public organizations as well as at home on several occasions including traditional holidays like the lunar New Year’s Day, Jongwoldaeborum (the lunar January 15), and Chusok (the autumn festival), national holidays and other public holidays.
Im Sung Bin, section head at the Academy of Social Sciences
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Jo Aug 29, 2022
Stability of earth and rockfill dams (ERD) usually includes sliding stabilities of steady seepage (at levels of normal water or flood water), earthquake and transient seepage (drawdown or heading-up).
In transient seepage such as rapid drawdown (RDD) unlike steady seepage, the phreatic surface, shear strength, boundary condition and effective stress of the slope soil, etc. dynamically change and they have coupled seepage-stress and nonlinear characteristics. These cause a number of problems with evaluating stability for transient seepage.
It can be a great expense to examine one by one the stability of earth and rockfill dams for rapid drawdown in civil engineering practice.
ERDs frequently met in civil engineering practice can be classified into homogeneous, sloping upstream core and central core according to whether they have an impervious core or not and where the impervious core exists.
Ri Yong Nam, a researcher at the Faculty of Earth Science and Technology, has proved that fully coupled seepage-stress analysis makes it possible to select the safest type for rapid drawdown among all common types of earth and rockfill dams and to approximately estimate the minimum safety factor for RDD from the steady safety factors.
The slope stability for RDD is very important in embankments such as a reservoir dam of relatively small storage capacity than its height, embankments under the effects of the high tide and the ebb tide, dams of agricultural reservoir, etc. In these cases, a central core dam (CCD) to improve the stability of ERD for RDD is recommended.
On the contrary, slope stability for RDD is not so important in embankments such as the reservoir dams of relatively large storage capacity compared to its height, embankments of gentle water level variation, etc. In these cases, an ERD which has larger steady stability for the same slope gradients is economically better and thus, a sloping upstream core dam (SUCD) is recommended.
The details about this is carried in his paper “Study on Stability Reduction Characteristics of Earth and Rockfill Dams under Rapid Drawdown Using Fully Coupled Seepage-Stress Analysis” presented to the SCI Journal “Advances in Civil Engineering”.
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Jo Aug 24, 2022
A research group led by Hong Sang Ryong, a researcher at the Faculty of Heat Engineering, has been working hard to make further achievements since he established an energy-saving recirculation system for dust collection and ventilation that can keep clean environment at the working places in a timber mill.
The system makes it possible to reduce power assumption to the minimum by adjusting the number of ventilators and dust collectors to the operation rate of wood working machinery.
They determined reasonable working parameters of the air control valve to prevent deposit of rough wood chips in the pneumatic conveying pipe.
They also selected optimal jet time and close-down time of the pulse system in the dust collector.
As a result, they reduced the number of working ventilators and dust collectors and ensured a long working life of the bag filter, which led to high working safety and low operational cost of the dust collection and ventilation system.
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Jo Aug 21, 2022
An inductive conductivity sensor is based on electromagnetic induction and it has some advantages such as robust structure and low manufacturing cost over conductive sensors. These sensors have no bare metal electrodes directly contacted with solutions, so they are free from damage by chemical corrosive solutions such as sulphuric acid and sodium hydroxide.
A transformer type sensor has robust structure and good linearity. It is easy to install and convenient to use in the industrial field. Using these characteristics, Kang Hwi Song, a section head at the Faculty of Electronics, has designed a new type transformer inductive conductivity sensor (TICS).
TICS has one or more magnetic cores. Its permeability values change with temperature and pressure. It is very important to compensate or eliminate the effects of magnetic core permeability change for improving the sensing performance.
TICS consists of a drive coil, a sense coil and a temperature sensor. Applying alternating voltage to the drive coil induces an ionic electric current in the solution around the sensor. This ionic electric current also induces an electric current in the sense coil which is proportional to the conductivity of the solution. Here, the two coils are encapsulated by chemical-resistant plastic material that protects them from corrosive electrolytes.
The equivalent loss resistances of the drive coil and the sense coil depend on both their turn number and frequency. From the investigation into the new model, he set the rational turn numbers as 10 each. The signal voltage was hardly affected when the drive frequency over 10kHz was used. As frequencies higher than 10kHz may cause magnetic loss, 10kHz was selected as a drive frequency.
In a word, it is important to use magnetic cores which have high permeability and small magnetic loss. He selected HS10 as the most suitable magnetic core for his purpose.
The drive coil and the sense coil are fixed on the PCB and welded to the lead wire. The main body encapsulates the two coils and PCB. The seal ring, fixing cap and gland are assembled each other. The seal ring and gland are for waterproof structure and the fixing cap is for the tank. Each part is fabricated of ABS plastic by a 3D printer. ABS plastic material has high chemical resistance and high water resistance and it is cheap. The thickness of the main body is 2 mm.
This sensing device is cheap and consumes less power. It also has simple circuitry, good linearity, high sensitivity and wide measuring range.
You can find more information in his paper “A new design of inductive conductivity sensor for measuring electrolyte concentration in industrial field” presented to the SCI Journal “Sensors and Actuators A: Physical”.
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