Jo Dec 5, 2022
Complex chemistry is an interdisciplinary discipline that elucidates the mechanism of the reaction of inorganic materials, including catalysts, in organic synthesis reactions and theoretically guarantees the development of more appropriate catalysts. Therefore, instructors should focus on experimental education to help student understand more vividly the chemical phenomena occurring in the microscopic world.
Ri Su Ryon, a researcher at the Faculty of Applied Chemistry, developed a virtual laboratory and a structural design support program of complexes that can provide conditions similar to actual experiments needed for complex chemistry. She has been using them to enhance the students’ faculties of analysis and structural design of complexes.
To this end, unlike previous lectures that relied solely on teacher’s explanation, she touches only important things in the lectures and gives secondary things as an assignment. She organizes experiments for application and independent structural design for the influence of factors so that they can learn everything by themselves.
Let us go through her teaching steps for crown ether metal complexes.
First of all, she touched key points only on the basis of enough self-learning.
She presented questions to be discussed in a pointed lecture as a preparation task and asked them to conduct virtual experiments related to their application in groups in advance.
On the basis of this, she led the students to draw new concepts from the similarities and differences in the structure and combination with metal ions in comparison with chain ligands, a chelating agent similar to crown ether.
Second, she developed her students’ analysis faculty through virtual experiments.
The group experiments conducted to dissolve potassium permanganate, an inorganic oxidant that can replace organic oxidant, in an organic solvent were shown for students to find faults. Then, she explained good points of the best one so that students could consolidate what they had learnt in the gist lecture. After that, she asked them to analyze by themselves the essence of the chemical phenomena occurring in the test tube by augmented reality technology.
Third, the structural design program was employed to enhance students’ independent structural design abilities.
She created a situation of which crown ether should be selected to separate Rh+ ions with a size similar to K+ ions from acetic acid solutions, allowing students to identify them based on what they had learned in the virtual laboratory.
Understanding the reason for differences in the stability constants of the 18-c-6 complexes of potassium and rhodium with very similar ionic radii and the need to modify the structure of the crown ether according to the nature of metal ions, each group was asked to propose a structure design and present it.
Finally, practical questions were presented to assess students’ abilities of analysis, judgment and overall systematization and each student’s performance was examined through the complex chemistry assessment system.
As mentioned above, while choosing reagents, performing experiments, finding out problems and learning how to draw conclusions all by themselves, the students’ abilities of creative thinking and practice have been significantly increased.
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Jo Dec 4, 2022
“Sinau” is a unique piece of music for tungso (Korean bamboo flute) composed by the people in Hamgyong Province. Singing and dancing was popular there from early days, so everybody had fine bamboo flutes in their homes. It was their practice to play the tungso whenever they wanted to. Such practice produced a large number of accomplished flutists and a tungso solo “Sinau”, which was played in traditional events like “Field Dance” and on other occasions
In modern ages, solo pieces like kayagum sanjo, komungo sanjo, haegum sanjo and flute sanjo were created with rapid progress of folk instrumental music in our country. Meanwhile, tungso sinau was dominant in Hamgyong Province, where there was a conspicuous development in tungso music.
“Sinau” in Hamgyong Province consisted of a series of pieces in several movements, every one of which was different in time, tempo and emotional color. Handed down through generations among them is passionate, enterprising and triumphant Hwimori Movement, which reflects the anti-aggressive, anti-feudal struggle and optimism of the people in Hamgyong Province. This high-toned movement has been developed with great artistic influences as it gives a vivid description of the locals’ personal qualities and patriotic fighting spirits.
After liberation, under the wise leadership of our Party to carry forward and develop our national music, “Sinau” was improved into a tungso solo and national orchestral music, an ensemble of national instrumental music, and chorus and orchestral music “For the Revolution”. It still resounds across the country, further boosting our people’s enthusiasm for the revolution and struggle.
Jong Son Ha, researcher at the Academy of Social Sciences
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Jo Dec 3, 2022
Ti2AlNb‒based alloys, so-called ordered orthorhombic (O (Cmcm)) phase alloys, have a chemical composition of Ti ‒ (18 ‒ 30) Al ‒ (12.5 ‒ 30) Nb (mole fraction, %). Since the discovery of orthorhombic (O) phase, Ti2AlNb‒based alloys have received special attention as a promising candidate for advanced aerospace and automotive application due to their high specific strength, excellent creep and oxidation resistance at elevated temperatures as well as good workability.
Up to now, many studies on the fabrication of Ti2AlNb-based alloys by casting, rolling and forging have been conducted, in which the major focus was set on the elimination of disadvantages such as microstructure segregation and inhomogeneity. It is because the thermodynamic properties of Ti, Al and Nb elements including a melting point, a density, a diffusion coefficient, etc. are very different.
Recently, powder metallurgy (PM) method such as spark plasma sintering (SPS) has been applied to the fabrication of Ti2AlNb‒based alloys, which made it possible to obtain fine and homogeneous microstructure. Several endeavors have been devoted to preparing PM Ti2AlNb‒based alloys from pre‒alloyed powder and elemental powders by vacuum hot pressing, and from pre‒alloyed powder by hot isostatic pressing (HIP). However, these as‒sintered compacts showed the microstructure with coarse grain size (>40μm), due to higher sintering temperature and longer sintering time. Therefore, the strength of these Ti2AlNb‒based alloys was not so high.
In recent years, several studies on the fabrication of high strength and ductility titanium alloys with nanostructured (NS) and ultrafine grained (UFG) microstructure have been reported. One process to achieve this microstructure consists of the preparation of NS or UFG powder by high energy ball milling (HEBM) and the consolidation of the powder into dense compacts by PM methods such as HIP and SPS. For instance, using the high energy ball-milled powder as a starting material, an ultrafine grained Ti‒6Al‒4V with high mechanical properties can be obtained.
In order to produce a high strength and ductility Ti‒22Al‒25Nb alloy from pre alloyed powder, Sim Kyong Ho, a researcher at the Faculty of Materials Science and Technology, has introduced HEBM with subsequent SPS. The process is as follows. Firstly, the Ti‒22Al‒25Nb pre‒alloyed powder with a weight of 75g was put in a stainless steel vial with bearing steel balls. HEBM was carried out in a high-energy planetary ball mill (QM-3SP4) under a high purity argon atmosphere for 20h at a rotation speed of 300 rpm. The HEBMed powder was directly loaded into a high-strength graphite mould, and subsequently consolidated by a LHPD250 SPS apparatus (FCT Co. Ldt., Germany) at SPS temperatures of 950℃ for SPS time of 10 min. After sintering, the sintered compact was cooled to the room temperature (RT) in the furnace. Finally, a sintered compact, with dimensions of φ50 × 15 mm, was obtained.
The Ti‒22Al‒25Nb alloy sintered at 950℃ for 10 min under the pressure of 50 MPa from the 20 h‒HEBMed powder showed the microstructure with a large amount of UFG/NS O-phase. The yield strength, tensile strength and elongation to failure were 1 092 MPa, 1 105 MPa and 9.4%, respectively. Compared with the referenced Ti‒22Al‒25Nb alloys, the Ti‒22Al‒25Nb alloy fabricated by HEBM and subsequent SPS exhibited higher strength and good ductility at the room temperature and high temperature. This indicates that HEBM with subsequent SPS is feasible for PM Ti‒22Al‒25Nb alloy with enhanced tensile properties.
More information about this is found in his paper “Fabrication of a high strength and ductility Ti‒22Al‒25Nb alloy from high energy ball-milled powder by spark plasma sintering” published in the SCI Journal “Journal of Alloys and Compounds”.
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Jo Dec 2, 2022
Ho Yong Ju, a researcher at the Faculty of Heat Engineering, introduced virtual reality technology to the practice at thermoelectric power plants, thus raising remarkably the teaching density and the cognition effect among his students.
The effectiveness is as follows.
First, as they can control any equipment in a virtual control room, they are able to notice the changes in the parameters of the plant and it becomes easier for them to be familiar with methods and characteristics of operation control.
Second, it saves time and practice procedures since all students can learn before necessary equipment in one room at the same time. In the past, it took a lot of time as the production site could hold only a few students in front of the machines at a time.
Third, it is possible for students to look closely at the structure and operation of all machines in a virtual situation. It leads to the raised efficiency of the practice.
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Jo Dec 1, 2022
Ryo Ok (5th century B.C ~ 4th century B.C.), a woman musician in the latter period of Ancient Korea, was a songwriter and an instrumentalist. She was one of the talented folk musicians. She was famous for writing and playing a lyric song “Konghuin” on a small konghu (a kind of traditional Korean stringed instrument) with 13 strings, while living with her husband near the ferry of the River Taedong in Pyongyang, the capital of Ancient Korea. Despite being poverty-stricken, she loved music so much that she always took pleasure in playing the konghu.
How “Konghuin” was written and what it is about are found in a number of books at home and abroad including “Kogumju”, “Haedongyoksa”, “Osansollim”, “Yolhailgi”, “Akso”, etc. One day Ryo Ok was told about a pathetic old man from her husband, who had returned from all day’s work on the ferry dock of the River Taedong. When the old man threw himself away into the River Taedong, his wife improvised a song playing the konghu with grief over his death. Feeling pity for the old couple that was drowned in the river, Ryo Ok, with the konghu in her bosom, composed “Konghuin” picturing in her mind the old grief-stricken lady playing the konghu. Ryo Ok enjoyed singing it along to the konghu in the moonlight or at sunrise and she taught it to her neighboring pupil Ryo Yong. From then, the song was spread across the country and even to the neighboring countries under the title of “Konghuin”.
The fact that many poets and writers in many generations have taken great interest in the song “Konghuin” and that different opinions of it are given in several documents gives a clear proof of the contributions of the ancient art of our country made to the development of the eastern art.
Ri Yong Ho, section head at the Academy of Social Sciences
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