Jo Jun 8, 2023
Pak Kwang Ok, a lecturer at the Faculty of Distance Education, has been giving importance to questions and answers in online lectures on “Insulant Production Engineering”, thus making remarkable achievements.
Her lectures are mainly based on two-way-exchange of knowledge between a teacher and students, not one-way transfer of knowledge from a teacher to students. In her lectures, students, as masters of learning, are able to think independently about problems and solutions to them, thus improving their independent faculties of learning, inquiry and presentation.
First, at the beginning of lectures, she associates new materials with what they have alrealy learnt in order to make it possible for them to draw the gist of a new lecture.
For example, in the lecture on synthesis of polyamide resin, she reminds them of the concept of a polyester resin so that students can easily understand what polyamide resin is.
Second, she raises problems for several occasions of teaching to make a question-and-answer session between a teacher and students, or students and students.
In the lecture on synthesis of polyester resin, for instance, she gives a practical discussion question “Which of the two methods of synthesis of PET resin is more advantageous and practical in terms of industrialization, directness or indirectness?” after explanation of production process of PET resin so as to make students have a discussion and present their discussion results.
In this course, students bring up their own questions that they found difficult to understand while working at factories, and find answers to them through discussions.
As mentioned above, she has been making her teaching more effective and raising her students’ practical abilities through question-and-answer sessions.
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Jo Jun 6, 2023
So Kyong Dok was a philosopher of materialism representative of the Korean medieval philosophy in the 16th century. His pseudonym was Hwadam or Pokjae.
He was born into a low-class aristocratic family in Kaesong in 1489. Although he was very clever from an early age, he could not start studying until he was 14 because of poverty.
Grown up in the historical environment from the late 15th century to the early 16th century when the contradictions of the feudal society started to be disclosed, he abandoned a government service from the start, out of discontent over a scramble for hegemony, arbitrariness and oppression of feudal ruling circles. Instead, he devoted himself to academic study and education of future generations, living in poverty all his life in Hwadam, Kaesong. That is why he was often called Teacher Hwadam.
Even though his philosophical idea represented the interests of low-class aristocrats, it exposed the misdeeds of the rulers of that time and expressed sympathy for the miserable life of peasants. Thus, it dealt a blow at the doctrines of Chu-tzu, which served as a basic idea of a ruling class, and exerted a great influence on the development of our country’s philosophy of materialism.
He died at the age of 57 in 1546. Reviewing his life, he said “I feel very happy with my perfect knowledge and satisfied with my worthwhile life.”
One of his books, which is still found, is “Hwadamjip” in four volumes.
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Jo Jun 4, 2023
A research team led by Kim Mun Hui, a researcher at the Faculty of Electrical Engineering, has developed a small wind power generation system capable of producing maximum power without a control circuit but a protective reactance coil.
A double-wound permanent magnet generator and a protective reactance coil can reduce harmonic loss and ensure maximum output of a wind turbine by increasing inductance and electromotive force coefficient.
The system consists of a wind turbine, a double-wound permanent magnet generator, a three-phase diode bridge rectifier, an inverter, load, etc.
The rotor of a 2kW wind power generation system is a horizontal axis with three blades and its radius is 1.8m.
The air gap flux density of the double-wound permanent magnet generator is higher than that of conventional ones and the air gap is 0.8mm.
The small power generation system is very effective for power generation of less than 10kW.
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Jo Jun 2, 2023
Pison Falls is located in Manphok Valley on Mt. Myohyang.
Clear waters forking down from the high cliff scatter around water drops, variegated by the sunlight like a seven-colour sunbow, as if the trains of fairies were hanging down.
The waterfall was given the name Pison Falls (pi means fly, son means fairy) as legend has it that fairies used to fly down there to enjoy the charming scenery of the Manphok Valley and fly up into the sky on a sunbow hanging over the fall.
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Jo May 30, 2023
A research team led by Jong Ji Song, a researcher at the Faculty of Mechanical Science and Technology, has suggested a method of modeling the output boundary conditions of a cardiovascular system, which is very important to properly simulate blood flow in a cardiovascular system.
Modeling of output boundary conditions of a cardiovascular system is, in essence, that of one of the several parts not reflected in a three-dimensional modeling for simulation analysis, that is, reflecting the change in the characteristic quantities in several parts omitted in the three-dimensional model as boundary conditions.
Blood vessels not reflected in the three dimensional model of a cardiovascular system are modeled by parameters such as resistance (R), elasticity (E) and compliance (C) to form an electrical circuit analogous model. From this model, output pressure waveforms are formed.
They modeled the output of the artery in a series connection of proximal resistance Rp to the parallel connection of compliance C and distal resistance Rd to reflect the transient of blood flow and the elasticity of a blood vessel. They modeled the coronary output in the combination of resistance of coronary artery Ra, coronary compliance Ca, microcirculation resistance Ram, myocardial compliance Cim, coronary vein resistance Rv and ventricular pressure Pim(t).
Then, from the model mentioned above, he obtained blood pressure waveforms at the artery output and coronary output of the model whose heart rate is 80 beats/min, cardiac output 120mL, diastolic and systolic pressures 80mmHg and 130mmHg respectively, split ratio of coronary and system circulation 0.04 and that of left and right coronary artery 7/3.
Setting these blood pressure waveforms as output boundary conditions, they performed analysis by ANSYS Fluent 19.2 during two heart rate cycles.
They applied the boundary conditions to five persons who were to have heart operations and compared them with the clinical data.
The comparison showed the error of systolic pressure, diastolic pressure and one cycle cardiac output were -1.07~0.86%, -1.1~0.88% and -0.89~1.87% respectively, which means this method of modeling output boundary conditions is very effective.
The suggested method can be applied to a cardiac operation simulating system for the simulation and analysis of the preoperative and postoperative state of blood flow in the cardiovascular system. In addition, it can predict the effectiveness of planned operations and relapse after operations, and provide clinical simulation results for postoperative healing programs.
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Jo May 26, 2023
Shock wave therapy (SWT) is a physical treatment that uses focused or unfocused shock wave to treat a variety of diseases including plantar fascitis, chronic pain, erectile dysfunction, bone ache, heart disease, and osteoarthritis. Most SWT devices use electrohydraulic or electromagnetic source that results in focused shock waves by a reflector or an acoustic lens. The ballistic SWT device, scaled down in size, consists of a hand piece within which compressed air is used to fire a projectile that strikes a metal applicator placed on the skin.
More reliable measurements and modeling on the pressure field of the device should be conducted in order to clarify the beneficial effect of shock wave.
Many new data on the pressure field of ballistic shock wave were presented by their successful studies although the experimental results were not identical with each other. The origin for different results in those literatures is likely related to the settings on the devices and measurement conditions, which might arouse ambiguity on clarifying physical and biological mechanism.
Pae Kyong Nam, a researcher at the Faculty of Physics, has developed a Lattice Boltzmann model based on mass and momentum conservation equations and Tait equation of state to elucidate propagation behavior of the ballistic shock wave. He has modeled the weak compressible flow with the mass and momentum conservation equations to obtain the macroscopic variables such as density, velocity and pressure. In order to solve the equations mentioned above, he has closed the system with a relation between the pressure and conserved variables by using the Tait equation of state (EOS).
The applicator used in the simulation was a convex shaped applicator with a 15mm diameter, referred to as unfocused, whose effective radius of curvature was 41mm, and the center was extended approximately 0.7mm from the edge.
A simulated pressure waveform is generally in good agreement with the previous experimental results, which has a leading positive phase and a subsequent negative phase.
You can find more information in his paper “Simulation of Acoustical Field of Ballistic Shock Therapy Device by the Lattice Boltzmann Method” in “Physics of Wave Phenomena” (SCI).
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