Jo Apr 10, 2024
Quantitative analysis of diffraction data usually refers to determination of amounts of different phases in multi-phase samples by using standard sample or simulation method. Quantitative analysis may also be understood as determination of particular characteristics of single phases including precise determination of crystal grain size and its structure and shape.
There are several methods of X-ray diffraction to quantify phases, but the Rietveld method has been perhaps the most useful tool in recent years as it accounts for the factors that affect the reproducibility of the intensity peaks (peak overlapping, presence of amorphous phases, and preferred orientation of crystallites).
Ro Thae Min, a researcher at the General Assay Office, has observed the quantitative value change when lattice constant is used, and not used, for fitting in the quantitative phase analysis of TiO2 by the Rietveld method.
The conclusions are as follows.
In qualitative analysis, the corresponding phase may not be correctly identified or unreconciled lattice constant in the ICSD database may be used. To avoid such mistakes, in the quantitative phase analysis, correct lattice parameters must be used for fitting. When lattice parameters are correct, Rietveld method is better than other X-ray diffraction quantitative phase methods such as internal standard method and direct method because it employs insturments, structure parameters and lattice constant of analogue phases altogether. Sometimes, however, lattice constant is not used for fitting. In this case, various lattice defects (crystallite size, rms strain, stacking and twin fault probabilities, etc.) are found in the whole diffraction pattern improvement process. Therefore, in the quantitative phase by Rietveld method, lattice constant should not be ignored to get correct quantitative value.
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Jo Apr 8, 2024
Short bed ion exchange technology utilizes fine mesh resin beads, a fully packed resin bed, and counter-current regeneration. These unique features help to improve exchange kinetics, reduce regenerant consumption and increase the concentration of strip solutions. Commercially, this technology has been extensively used in the following areas: separation and purification of strong mineral acids, removal and recycle of dissolved metals in the surface finishing industries, and production of high purity water.
The most frequent questions concerning short-bed ion exchange relate to flow distribution, because the column is only a few centimeters tall and it has to treat tremendous amount of solution in a short time.
There have been a lot of introductions of the advantages of a short-bed ion exchange column, but no articles on its detailed geometric size and design have been published yet. What is more, no information has been found on the influence of the structure and geometric size of a flow distribution plate on the flow distribution characteristics of the short-bed ion exchange column and on the optimal design based on the influence.
Kim Yong Min, a section head at the Faculty of Chemical Engineering, has discussed the influences of several parameters on flow distribution in Recoflo by using CFD program and consequently done some research to design a reasonable flow distribution plate for optimization of ion exchange processes and enhancement of separation efficiency.
The simulation results showed that 60 radial flow channels and 3 circumferential flow channels were the reasonable parameters for ensuring even flow distribution through the bed in the short-bed ion exchange column.
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Jo Apr 7, 2024
Kyuhyonginjiui, the first surveying instrument invented in Korea in 1467, was used to identify targets and directions on the ground and measure heights and distances.
It was also called injiui.
The instrument consists of two parts; a vertical axis and a horizontal scale plate that revolves around the axis vertically.
Kyuhyong, a device for aiming at target objects is attached to the axis, goes up and down vertically.
There are 24 directions inscribed on the plate for direction finding.
You can aim at any objects by turning the vertical axis round and moving kyuhyong up and down along the axis.
The compass installed on the instrument helped correct aiming.
Kyuhyonginjiui survey was, in principle, the same as present plane table surveying.
Such instrument for surveying was not found in European countries until the late 16th century, and a similar one to Kyuhyonginjiui was finally built in a German factory in the 17th century.
The fact that Korean ancestors made and used such a surveying instrument as Kyuhyonginjiui a century before other countries demonstrates their high creative wisdom and talent.
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Jo Apr 5, 2024
Plastic products have high productivity for their high corrosion resistance and large-quantity injection molding. When they are coated with metal decoration, they have higher durability and shock-resistance. It means they have longer life time.
Extrinsic decoration methods include evaporation, plating and electrophoresis, of which plating is most widely used. The most suitable plastic for plating is acrylonitrile-butadiene-styrene (ABS).
Decorative nickel plating of acrylonitrile-butadiene-styrene (ABS) plastics has depended on pretreatment of precious metals including Cr and Pd, but it is subject to restriction due to both environmental pollution by chromium oxides and increasing prices of precious metals.
Kim Kyong Chol, a researcher at the Faculty of Chemical Engineering, has found a reasonable method of etching and forming a conducting layer in the pretreatment process of plastic products, and investigated the influences of some factors.
Permanganate was used for etching and the conducting layer was formed by complexing agent of tartaric acid and lactic acid. First, he investigated the etching characteristics in terms of amounts of potassium permanganate, phosphoric acid and sulfuric acid, and then, he assessed the characteristics of the conducting layer with respect to the amounts of metal ion, mixed ligand and temperature.
The scanning electron microscope (SEM) images, X-ray diffraction (XRD) patterns and electric resistances confirmed that the current etching is environmentally friendly and the electric resistance of formed Cu2S is below 50Ω/cm2.
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Jo Apr 4, 2024
Moran Hill is located on the bank of the Taedong River, which flows through Pyongyang City. It was called Kumsu Hill during the feudal Joson dynasty. Later, it was given the name “Moran Hill” as it resembles a peony (pronounced like ‘moran’ in Korean)
Regarding it as a pride of Pyongyang from olden times, Korean people have created many legends related to the hill.
The legends reflective of the attachment to and love for Moran Hill are associated with the pride in having the beautiful Moran Hill and with the patriotism of Korean people who defended it from foreign aggressors.
The legends in praise of the beauty of Moran Hill are “Hungbudong” and “Story of Chongryu Cliff”. The former is about a mysterious spring and the latter says that the beautiful Chongryu Cliff was formed by the wonder of nature of the Dragon King, who was impressed by a boy with a heart of gold in Pyongyang.
The beautiful and noble customs and manners of Pyongyang people are depicted in such legends like “Chongryu Pavilion in Moonlight” conveying the sincerity of a boy in Kangdong who tried to save a girl in the Walled City of Pyongyang from misery and “Door of Happiness” reflective of the sentiments of the people.
Among the legends that represent the fighting spirit of the Pyongyang people who defended the beautiful city Pyongyang are “Ulmil Warrior” about a warrior who devoted himself to the defense of Pyongyang and Moran Hill, and “Kye Wol Hyang and ‘A Man of Heroic and Noble Mind’” about the struggle of Kye Wol Hyang, a young woman, who turned out in the fight against Japanese invaders.
As mentioned above, the legends of Moran Hill serve as priceless cultural heritage of our nation as they represent the desire and aspiration to boast of the beauty of Moran Hill to the world, the patriotism of Korean people, who defended it against foreign aggressors, and their beautiful sentiments.
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Jo Apr 2, 2024
37th Sci-Tech Festival of Kim Chaek University of Technology was held in the university indoor stadium from February 20 to 22, Juche 113(2024).
The subject was “Science and technology ― decisive guarantee for the fulfillment of the five-year plan”. The festival aimed to solve scientific and technological problems of key importance in fulfilling the five-year plan on the basis of the successes achieved in the research work for the implementation of the resolutions of the 8th Congress of the Workers’ Party of Korea and plenary meetings of its Central Committee by the lecturers, researchers, post-graduate students and students of the university.
The festival took the form of scientific and technological paper readings, exhibition contest of units and exchange of new technology in seven sections including machine and transportation, information and communication, metal and chemistry, and electronics and automation. On display were 190-odd research findings including “establishment of pig iron production process by energy-saving oxygen heat blast furnace”.
“Portable defibrillator” by Ri Yong Chol, a section head at the Bioengineering Institute of Mirae Sci-tech Centre, and other 70-odd items were highly appreciated.
Upholding the noble intention of the respected Comrade
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