Jo Apr 14, 2022
A research group led by Ri Ju Hyok, a section head at the Faculty of Heat Engineering, has invented a vaporizer that vaporizes cryogenic liquid oxygen to supply to consumers.
It is an atmospheric source cryogenic vaporizer that turns cryogenic liquid oxygen into gas by cryogenic distillation method.
In practice, the demand for oxygen is unpredictable. To meet this flexible demand, liquid oxygen is usually stored in the cryogenic tank and is vaporized whenever needed. The vaporization of liquid oxygen is conducted by means of a cryogenic vaporizer.
The vaporizer is a vertical heat exchanger, its cross section is of an 8-pointed star type and it vaporizes cryogenic liquid by atmospheric heat.
To determine the optimal parameters of a vaporizer, they studied 4 items: growth process of frost on the surface of the heat exchanger when liquid oxygen is vaporized, the property of frost, the pulse phenomenon in the heat transfer pipe and the destruction of frost on the surface, and the characteristics of air flow in the surrounding of a heat exchanger.
The cryogenic oxygen liquid vaporizer is extruded of aluminum alloy of good conductivity.
As its heat source is based on only the air in the atmosphere, environmental problems such as pollutant emission and noises are not arisen.
It is also applicable to the vaporization of other cryogenic liquids like nitrogen, argon, etc. as well as oxygen.
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Jo Apr 13, 2022
Choe Yong Son, a researcher at the Faculty of Physics, realized the computerization of an experiment device to measure the characteristics of glow discharge plasma.
Compared to the previous devices with analog meters, the computerized device is equipped with an embedded system and a touch-panel interface, which makes it possible to supervise and analyze experimental processes, and to display the results. It also ensures high accuracy in measurement and short time of measurement along with intuitiveness and effectiveness of experiments.
The device consists of a power supply, a probe voltage stabilizer, a triangular signal generator, a discharge current sustainer, a current-to-voltage converter, a voltage signal detector, a matching unit, and a computer. The main characteristics to measure are electron density and electron temperature. A linearly increasing voltage is applied to the electrostatic probe, which is placed in the discharge region, and the current to the probe is captured at a regular interval, in order to gain voltage-current measurement points of the probe.
These measured data are treated by 3-order spline interpolation and then by weighed polynomial method to obtain a voltage-current curve of the probe. Necessary features are to be derived from the characteristic curve, and these features are utilized to determine electron temperature and electron density. All these operations are automatically performed through its embedded system and touch-panel interface.
This device can increase the measurement accuracy of probe voltage and current by more than 20 times and, as a result, as many measurement points as possible are available. Therefore, we can eliminate scale errors, which were indispensable in the past, and decrease random errors down to below 0.5% (in analog meter: 4.2%). In addition, offline experiments may become possible by the combination of serial communication and network communication.
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Jo Apr 12, 2022
From the viewpoint of interpretation and methodology, quantum mechanics as one of the greatest achievements in the field of physics in the 20th century involves two formulations, i.e., the traditional standard formalism and non-standard formalism such as quantum mechanics in phase space, quantum trajectory formulation and path integral method.
Hibert-space formalism as the standard formalism yielded an excellent mathematical formulation for explaining the microscopic world such as atoms and subatomic objects. After that, the trajectory-based quantum mechanics such as Bohmian mechanics was proposed in order to improve mathematical formulation of quantum mechanics. Quantum mechanics in phase space also attracted a great deal of interest from the aspect of mathematical formulation, but the tasks of establishing an alternative independent formalism of quantum mechanics still remained not accomplished.
After as long as 15 years of painstaking effort, Jong Chol has proposed that it would be possible to establish an alternative autonomous formalism of quantum mechanics in phase space by means of a statistical method.
The proposed theory as a new formalism of quantum mechanics in terms of ensemble in phase space leads to obtaining within the framework of its theory the fundamental quantum-mechanical equation without recourse to other formulations of quantum mechanics, and gives the idea for operators pertaining to dynamical quantities.
The theory also demonstrates that the system of operators given by quantum mechanics in phase space is a complete system of quantum operators and it is possible to explain, using the fundamental equation, the structure of quantum mechanics in phase space and the approximation of the fundamental equation of the present formalism to the Schrödinger equation. Therefore, it concludes that quantum mechanics in phase space is the general formulation comprising the formulation in configuration space as a special case.
This formalism provides reasonable results of quantization by dealing with some simple cases such as the quantization of harmonic oscillation, the two-slit interference and the uncertainty relation, which confirms the validity and generality of this formalism.
In particular, this formalism shows that it is possible to easily obtain the relativistic wave equation by making use of the relativistic phase velocity without treating the problem of linearizing the Hamiltonian operator as in the case of the deduction of the Dirac equation.
The ultimate outcome this formalism produces is that it has been confirmed that primary and general matters of quantum mechanics can be studied reasonably within the framework of statistical mechanics.
This information is from the essay “Ensemble in phase space: Statistical formalism of quantum mechanics” presented by Jong Chol, a researcher at the Faculty of Materials Science and Technology, to the SCI Journal “Pramana Journal of Physics” 92:83(2019).
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Jo Apr 11, 2022
The contests ended on March 28, 2022.
The first contest was held on March 11-14. About 19 900 people from tens of countries and regions including our country, China and India took part. 178 participants competed in Category 1, 2 105 in Category 2, and 6 227 in Category 3 and 11 415 in Category 4. Category 1 set forth 5 problems, none of which were challenge problems.
A total of 48 contestants won the first place in Category 1 ― 18 from the DPRK, 5 from China, 15 from India, 1 from Peru, 1 from Singapore, 2 from Bangladesh, 1 from Portugal, 1 from the UK, 1 from the US and 3 from Japan.
9 out of the 18 winners of our country are students at Kim Chaek University of Technology.
37.5% of the world winners are from the DPRK, and 18.75% are from KUT.
KUT students amount to half the 18 DPRK winners.
In the meantime, a student from KUT took the first place in Category 2.
The second contest went on from 25 to 28.
About 16 900 people from tens of countries and regions including our country, China and India took part. 93, 666, 4 581 and 11 593 contestants belonged to Category 1, Category 2, Category 3 and Category 4 respectively.
4 non-challenge problems were presented in Category 1.
Category 1 witnessed a total of 21 winners ― 15 from our country, 3 from China, 1 from Bangladesh and 2 from Japan.
All of the 5 students from Kim Chaek University of Technology took the first place in Category 1.
Our country has as many winners as 71.428% of a total of 21, and 23.809% are KUT students. KUT students account for 33.3% of DPRK winners.
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Jo Apr 7, 2022
What is important in teaching English is to develop students’ practical skills and to train them to be active in thinking in English.
To achieve this goal, you can apply the principle of discovery to teaching English like any other subjects.
In general, the application of this principle means that a teacher does not give a conclusion in advance but leads them to acquire new knowledge like concepts and principles through the self-enquiry based on their activeness and creativity.
When teaching English, a teacher has to make students read textbooks or do exercises by themselves and have a discussion, and has to give an explanation on the problems important and difficult to understand only.
This teaching method consists of 4 stages: environment and assignment, discussion, leading and solution.
Environment and assignment:
In this stage new teaching materials are shown.
On the screen a teacher displays a certain text which is suitable for the level of students and related to their majors so that it can stimulate their enthusiasm for study. Also, the materials should be up-to-date, connected to everyday life and scientific knowledge and contain new vocabulary and grammar. Such materials are worth discussion.
Discussion:
Students have a discussion between themselves or with their teacher over specific questions given by the teacher. When a teacher arranges a discussion on relatively difficult questions, students form their opinions about them. In the discussion students compare and evaluate different opinions to reach an agreement.
Leading:
This stage leads students to achieving goals. By asking leading questions, a teacher leads students’ thinking to the world of analysis and summing up activities. Then they can discover new things by themselves.
Solution:
In the stage a teacher encourages students to find as much information as possible related to the given text, to make compositions using dictionaries and to present them before the class. Then the teacher comments on them, summarizes the main point and evaluates their study activities.
In summary, this teaching method helps students discover anything necessary by themselves as well as simple grammar rules.
In order to raise the teaching effectiveness of this method, you should present assignments and thinking questions commensurate with their levels and abilities, and organize your lectures in an interesting and varied way so that students can be fully involved in them.
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