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 Mar 25, 2022
When mining penetrates increasingly deeper in open pit mines, the mines take some kind of funnel shape. The deeper the funnel is, the greater the expense for transport gets. In order to accelerate and cheapen transport while maintaining the flexibility offered by truck transport, several types of Trucklift systems have been employed.
These systems are generally similar in structure and operating principle and consist of a slope hoisting plant, platforms, tracks and loading stations. Friction winders or drum winders are used as a hoisting machine and the system can be equipped with either single or double tracks.
When a truck is driven onto and off the platform vertically to the transport direction at the loading station, the platform moves on the rails by the weight of the truck although the winder comes to a halt. Then the truck changing might fail because there may be a difference in the height between the platform and the loading station. So platform arrestors that work when the platform reaches are provided at loading stations, ensuring that the platform is held in the position when the load changes by truck changing.
In addition, when the truck is driven in parallel with the transport direction, the platform also moves on the rails and there appears the varying clearance between the platform and the edge of the loading station. Truck changing may be hindered by this clearance. However, the moving direction of the truck and the platform are the same, so we can avoid the effect of the movement of platforms during truck changing without the help of arrestors by a reasonable design of the structure of loading stations and platforms. For this reason, it is necessary to make a deep study of the moving process of the platform during truck changing.
The moving process of the platform can be simulated with ADAMS and MATLAB/Simulink.
Especially, the simulation of the truck changing process in the Trucklift slope hoisting system where trucks stand parallel to the transport direction on the platform and the analysis of the movement of the platform and the force of rope can provide us with important data for the design of a platform, a loading station and an arrestor.
According to the simulation results, in the Trucklift slope hoisting system with a drum winder, normal truck changing can be realized by making a reasonable design of the platform and the loading station after determining the moving displacement of the platform,
In the Trucklift slope hoisting system with a friction winder, the need to arrange arresters at loading stations must be examined to avoid slipping of ropes in the drum groove due to the movement of the platform during truck changing. If arresters have to be provided at loading stations, the force acting on the platform obtained from the simulation can be used as reference data for the design of arresters.
You can find more information about this in the paper “Simulation for Motion of Platform During Truck Changing in Trucklift Slope Hoisting System in Open Pit Mines Using ADAMS and Matlab/Simulink” by Han Tok Hyong, an institute head at the Faculty of Mining Engineering, presented to the SCI Journal “Arch. Min. Sci.”.
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Jo Mar 24, 2022
Any application including ecological environment monitoring, target tracking, traffic control and agriculture surveillance needs a routing technique for forwarding data sensed by sensor nodes to the base station (BS) or the monitoring centre through several relay nodes.
In topology such as tree or mesh structures used in many applications, sensor nodes are often distributed randomly in areas beyond the reach of people. However, in a one-dimensional queue WSN, nodes are uniformly and densely deployed on a line and this type of network offers many applications such as ecological environment monitoring system along a river, fire monitoring and controlling system along a corridor, smart traffic monitoring system along a road, a tunnel or a bridge, and petroleum pipeline remote monitoring system. In such a one-dimensional queue WSN, the geographical location of each node is fixed, the distance between two neighboring nodes is always uniform, and sensed data can only be forwarded in one direction to the BS. Because of this, the network becomes more unreliable and has high probability that it may be partitioned if some continuous nodes have run out of their energy. Therefore, it should be a key factor of designing a routing protocol in one-dimensional WSNs to ensure energy efficiency and sensed data relay latency by balancing and optimizing energy consumption.
Existing routing protocols in WSNs including a one-dimensional queue WSN attempt to find the path of minimum energy consumption from the source node to the BS to achieve optimal energy consumption because transmitting data consumes much more energy than collecting data.
In one-dimensional queue WSNs, the network topology is linear, so the identification of each node is unique and continuous and the geographical position is certain. From such characteristics, the application of an algorithm that includes a sleep mode in the routing design through timeslot allocation could prolong the network lifetime by ensuring energy efficiency and also satisfy the requirement of sensed data relay latency considering the interference between nodes in some degrees.
This is a distributed energy-efficient opportunistic routing algorithm accompanied by timeslot allocation (DEEOR-TA) using specific network topology of a one-dimensional queue wireless sensor network.
DEEOR-TA algorithm is run in several rounds and each round involves two phases, i.e. clustering-based routing tree construction accompanied by timeslot allocation and data transmission.
Four measurable metrics are defined to evaluate the performance of DEEOR-TA in a one-dimensional queue WSN, i.e. average of residual energy, variation of residual energy, number of dead nodes, and network lifetime.
The simulation results show that the proposed protocol supports better energy efficiency than other existing protocols, and therefore, it can help to prolong the network lifetime.
This paper titled “A distributed energy-efficient opportunistic routing accompanied by timeslot allocation in wireless sensor networks” presented by Ri Man Gun, an institute head at the Faculty of Communication, is carried in the SCI Journal “International Journal of Distributed Sensor Networks”.
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Jo Mar 22, 2022
Choe Song Bom, a section head at the Faculty of Information Science and Technology, has developed an image processor to obtain input images from hand-based shoe design images, and on the basis of it, he has continued to invent a new method of serial expansion and realize it in a serial expansion program.
This program consists of 3 parts: noise reduction, contour highlight, and serial expansion.
Its application reduced design hours from 10 to 3 and improved design accuracy from 90% to 98%.
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Jo Mar 21, 2022
In keeping with the actual conditions where communication equipment is on the increase in its kind and scale, the research team led by An Chong Il, a researcher at the Faculty of Information Science and Technology, has developed a network management system using a simple network management protocol that enables the integrated management of individual pieces of communication equipment.
Thanks to it, it became possible to manage different pieces of existing communication equipment in an integrated way and also to satisfactorily supervise and manage newly-added ones.
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