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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Jo Dec 28, 2023
The empirical Bayes approach has become a common method in statistical situations. It is a statistical method for successive Bayes decisions when prior distribution is unknown but many past data are given. The inference for truncation parameters is important for evaluation of upper or lower bounds of population, so it has been studied extensively. Many authors have considered the case of one-sided truncated distribution but in practice, we face the case of two-sided one, too.
Ri Sung Hyon, a section head at the Faculty of Applied Mathematics, has investigated empirical Bayes estimation for truncation parameters of two-sided truncated distribution under squared error loss.
First, he constructed the empirical Bayes estimators of truncation parameters using size two samples and proved the asymptotic optimality of the estimators. Then, he proved that the probability of reverse estimation converges to zero as sample size goes to infinity. Finally, he presented an example to show the soundness of his theoretical results and conducted a simulation on the performance of the proposed empirical Bayes estimators.
The new proposal of using size two samples could be extended to the case of multi-dimensional truncated distributions defined on hyper-cubic domain.
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