Line-start permanent magnet synchronous motor (LSPMSM) is a self-starting PMSM, which features both induction motor and conventional synchronous motor. The asynchronous torque generated by the stator-rotating magnetic field and its interaction with the squirrel cage rotor drives this motor. In normal operation, the rotor is driven at synchronous speed and the cage rotor is not actuated. Its operating principle is the same as that of a conventional synchronous motor. What is different is that the PMSM provides a permanent magnet (PM) with a magnetic field necessary for energy conversion, so it is simple in configuration and significantly high in energy density.

With the efficiency and power factor higher than induction motors, LSPMSMs have found wide application in various fields such as light industry, textile industry, oil industry, chemical industry and transportation. In particular, they have incomparable advantages over induction motors in respect of fans, compressors, pumps, etc. Therefore, there is a world trend to replace induction motors with them as they are stable in rotational speed and have high efficiency and power factor.

Many researchers have studied the starting, synchronizing and efficiency enhancement of LSPMSM and investigated the influence of various parameters. There is no research data available that detailed the rotor configuration, design method and manufacturing method for the induction motor to be modified to LSPMSM.

Ki Yong Chol, a researcher at the Faculty of Electrical Engineering, proposed a rotor configuration scheme to convert a three-phase low-power induction motor into LSPMSM, carried out the optimal design of the rotor, and simulated the motor characteristics under different operating conditions.

To verify the simulation results, he built a prototype and conducted a test. The test results were in good agreement with the simulation results, showing that the efficiency and power factor increased as compared with conventional induction motors.

Scroll and mounting belong to the precious national culture and art that the Korean ancestors created and developed together with Korean painting.

A scroll is a form of Korean painting with pictures or words that are mounted for hanging down or rolling.

A scroll is decorated on its border with thin strips or cloth that goes with the picture, and a horizontal bar is fixed to the bottom of the scroll so that it unrolls when it hangs down.

Korean paper is pasted to the back of the scroll for hardening, and paraffin is spread all over the back and rubbed for preventing folding lines.

A scroll amplifies the national taste in adorning pictures.

It also helps long storage and easy handling of Korean painting works.

Mounting is ornamentation of appearance of pictures including their backs and borders.

Vividly taking the national form from early ages together with Korean painting, the intrinsic national painting, mounting has developed, divided into scroll, folding screen, picture album, album of calligraphic works etc., according to the mission and purpose of pictures, individually with their own features.

Mounting plays an important role in enhancing the beauty of paintings and it provides an important guarantee for keeping painting works to posterity.

Density and viscosity are important quantities which describe the physical properties of liquid, and density is the most important thermo-physical property of hybrid nanofluids.

Many methods were proposed for density measurement of density or viscosity alone. Resonant sensors can measure density and viscosity simultaneously, so it has many applications in the fields of physical or chemical sensing in liquid.

In the measurement of liquid density and viscosity, the change of resonance parameters due to the parasitic parallel capacitance of resonator affects measurement accuracy.

In order to improve accuracy, An Nam Chol, a section head at the Faculty of Electronics, proposed a method for compensating the parasitic parallel capacitance of resonator by adding an electrode. In addition, he modeled a resonant sensor with a compensation electrode and determined the structural parameters through simulations and experiments.

He conducted some experiments to examine the effect of this method. The experimental results show that this method is valuable for compensation of parasitic parallel capacitance of an immersed resonant sensor in liquid.

You can find the details in his paper “Accuracy improvement of resonant sensor by an additional electrode in the measurement of liquid density and viscosity” in “Sensor Review” (SCI).