Jo Jan 9, 2024
Water is commonly used for industry, agriculture and office and domestic consumption. Water shortage is one of the most worrying problems and it is related to poor management and inefficient use of water resources. Therefore, efficient use and monitoring of water are very important. Here, water level sensing is of key importance. Many physical properties of water like relative electrical permittivity, resistivity, thermal conductivity, buoyancy, hydraulic pressure, absorption of radiation, surface reflection of sound or light waves, etc. are used for water level sensing.
Although a variety of structures of capacitive water level sensor and low capacitance probing techniques have been proposed, it is still important to develop a new type which is more convenient, flexible, simple, low-cost and easy to make for widespread application in homes and offices.
Kim Chol Man, a section head at the Faculty of Earth Science and Technology, has proposed a new low-cost capacitance-type water level sensor and low capacitance probing technique. Unlike the conventional low capacitance probing techniques which involve analog circuits such as AC-bridge, negative impedance converter, analog switch, oscillator, multiplexer, phase shifter, etc., his method is based on a direct capacitance-to-time conversion principle by a single microcontroller unit (MCU).
For test and verification, he made a prototype water level controller. The results of the experiments showed that the repeatability and linearity of the sensor are satisfactory within the tolerable limit of 0.5% full scale.
The prototype water level controller is simple and cheap enough for home and office use.
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Jo Jan 8, 2024
Seed mutagenesis can be classified into cross-breeding and artificial mutagenesis.
Crossing, a technique for producing new varieties of seeds by crossing seeds in different genera, species and varieties requires a lot of time and labor although it is cheap.
Artificial mutation, a technique that activates mutagens in seeds, takes less time and labor and it does not cost much to make a device for it. But its drawback is that mutant seeds reveal low availability.
Another artificial mutation method is based on transgenic technique. It is excellent because target genes are injected, but it is very expensive and complicated.
Therefore, Kang Myong Hyok, a researcher at the Faculty of Physical Engineering, based on the analysis of the physical factors of mutation, has developed a device that can serve as a mutagen with simultaneous action of more than two physical factors.
The physical factors he applied are pulsed high-voltage electric field that can change electrical properties of living organisms, shock wave that can momentarily provide energy strong enough to destroy cell membranes, and strong ionization field to make the surrounding environment a strong active field from an inert field stabilized in the growth activity.
He also obtained experimental results for determining suitable operation parameters necessary for mutation.
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Jo Jan 7, 2024
The lunar New Year’s Day is a traditional holiday our people have celebrated from ancient times.
What is important in our people’s custom of celebrating the day is a variety of special dishes ― rice cakes such as glutinous rice cake, steamed rice cake and fancy rice cake, rice cake soup, several kinds of pancakes, fruit punch, fermented fish, roasted meat, etc.
What is the most special of all of them is a special fruit punch beverage called sujonggwa.
The fruit punch is a traditional drink made of dried persimmon, ginger, cinnamon, honey, etc.
Here are the steps to make fruit punch.
First, slices of clean ginger and cinnamon powder are boiled in separate pans.
When the aroma of ginger and cinnamon soaks out enough, they are removed from the pan. Then, the exudates are mixed before honey is added.
After that, a dried persimmon without any seeds is put in the mixture to be stored in a dry place for some time.
Finally, some pine nuts are floated when serving in a vessel.
The knowhow of making the fruit punch is to boil ginger and cinnamon separately as they might lose their own indigenous flavor by affecting each other.
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Jo Jan 3, 2024
The 4th Students’ Memory Contest was held from November 6 to 10, 2023. Excellent students selected from fast reading contests among universities of technology and teacher training colleges took part. The contestants competed through 10 items including fast number, virtual events and dates and random words. The winner of the contest is Ri Ji Hun, a student in the fifth grade at the Faculty of Electrical Engineering, Kim Chaek University of Technology. The striking news is that he displayed his ability high enough to break the memorizing standard set in the world memory contests in the items of memorizing random words and speed cards. Now he is making further efforts to prepare himself to be a world-startling master of memory.
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Jo Jan 2, 2024
The Korean name for a kite, yon is thought to have been derived from a Chinese character with the same sound meaning ‘bird of prey’ since a kite made of paper flies high in the sky just like a bird of prey. In our country, kite-flying used to continue from the beginning of winter to the end of cold weather the following year. The period from the lunar New Year’s Day to the lunar January 15 particularly buzzed with kite-flying.
The period was so animated that it was called children’s kite-flying holiday. The kites traditionally handed down in our country are of different shapes, largely divided into square and ray.
The popular kites are decorated with colored paper cut into different shapes like thin strips, skirt, half-moon, butterfly, etc.
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Jo Jan 1, 2024
Begun in Ancient Joson age, our nation’s custom of celebrating the lunar New Year’s Day has been inherited to this day through a long period from Koguryo, Koryo and feudal Joson dynasties.
Regarding the day as the first day of a new year that brings hope, people of all ages and both sexes prepared various kinds of dishes, dressed themselves in new clothes, held memorial services, made New Year’s visits and played varied games.
In an old book “Tongguksesigi” is recorded as solbim for dressing in new clothes, as charye for holding memorial services, as sebae for visiting relatives and seniors to make New Year’s bow, and as sechan and seju for dishes and spirits respectively.
In the morning of the New Year’s Day, our people held services for their dead ancestors and visited their graves followed by visits to their relatives and seniors to wish good luck for the year. When children, dressed in new clothes, made a bow to the elders, the elders wished them good luck and served them food. People placed a box (called seham) in front of their houses for visitors to put pieces of paper with their names on. Later, they were said to be replaced with New Year’s cards. Dishes prepared for the day were rice-cake soup, steam rice cake, yakbap (glutinous rice mixed with sugar, dates, chestnuts, pine-nuts, sesame oil, etc.), glutinous rice cake, dumplings stuffed with honey and sesame, fried glutinous rice cake, fish, slices of boiled meat, fermented fish, liquor, etc., among which rice-cake soup, yakbap and fried glutinous rice cake were regarded as musts.
Yakbap was considered to be of superior grade for memorial services and guest service.
Major folk games played on the day were yut-game and children’s kite-flying and tipcat.
The custom of celebrating the lunar New Year’s Day mirrors the beautiful characteristics of our people who respect the elders and betters, value etiquette and are possessed of optimism.
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