• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.11
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• pp.1558-1563
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• 2015

In this paper, temperature characteristic analysis was performed by using a thermal equivalent circuit. To suppress the temperature rising, the cooling fan was installed in rotor. The temperature of permanent magnet was reduced from 66[$^{\circ}C$] to 55[$^{\circ}C$] by installing the fan. The temperature of the permanent magnets is difficult to measure. Therefore the temperature of end winding was measured directly by the thermo couple. The validity of this study was demonstrated as compared the calculated results with experimental ones.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.3
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• pp.411-416
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• 2015

This paper presents the thermal modeling and analysis of Line power Start Permanent magnet Motor (LSPM). Thermal analysis of electrical machines is important because temperatures that are consistently too high will reduce the life time of machines and may lead to serious failure. Coefficients of convection are calculated according to the types of operating conditions. And computational fluid dynamics (CFD) technique is performed in order to predict thermal characteristic. The results are compared to the test results.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2310-2316
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• 2011

In order to apply Interior Permanet Magnet Synchronous Motor(IPMSM) to the propulsion system of the railway transit, 110 (kW) class IPMSMs with high-power density are designed as a concentrated winding model and a distributed winding model in this study. The concentrated winding model designed in this study is 6 poles/9 slots and the distributed winding model is 6 poles/36 slots. In general, the eddy current losses in the permanent magnets of IPMSM are caused by the slot harmonics. The thermal demagnetization of the magnet by the eddy current losses at high rotational speed often becomes one of the major problems in the IPMSM with a concentrated windings especially. A design to reduce eddy current losses in permanent magnets design is important in IPMSM for the railway vehicle propulsion system which requires high-speed operation. Therefore, a method to devide the permanent magnet is proposed to reduce the eddy current losses in permanent magnet in this study. Authors analyze the variation characteristics of the eddy current losses generated in permanent magnet of the concentrated winding model by changing the number of the division of the permanent magnets.

• Journal of the Korean Magnetic Resonance Society
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• v.23 no.3
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• pp.81-86
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• 2019

Overhauser dynamic nuclear polarization (O-DNP) has been an efficient method to boost the thermal nuclear polarization in liquids at room temperature. However, O-DNP for a benchtop NMR using a permanent magnet has remained unexplored yet. In this work, we report the development of an O-DNP system adopting a permanent magnet of 1.6 T. Q-band (~43 GHz) high-power amplifier produced 6 W microwave for saturation. Instead of resonator, we used an open-type antenna for the microwave irradiation. For several representative small molecules, we measured the concentration and frequency dependences of the enhancement factor. This work paves the way for the development of a benchtop DNP-NMR system overcoming its disadvantage of low quality signal when using a permanent magnet.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.2
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• pp.231-239
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• 1995

When the complete denture is made, the record base for jaw relation is divided into temporary record base and permanent record base. However, The temporary record base include some disadvantages such as, the lackness of intimate contact between model and base, the lackness of retention during the jaw relation registration, When we obtained jaw relation the permanent record bases made from heat curing resin were utilized. We could get several advantages as follows : 1. The permanent record base provided intimate contact between the model and record base. 2. In fabricating occlusal rim on record base, the dimensional change of record base was little because the permanent record base was lesser influenced to thermal change of occlusal rim than the temporary record base. 3. At the stage of jaw relation, the retention of final denture could be early checked. 4. It could be able to get more accurate registration of jaw relation because all procedure were done on the same base during the jaw relation, artificial teeth arrangement, try-in, and final denture construction. 5. Although there was an inconvenience due to double curing procedure, the shrinkage rate in resin polimerization was relatively reduced so that more dimensional stability could be taken.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.4
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• pp.498-504
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• 2012

The water-cooled Permanent Magnet Linear Synchronous Motor (PMLSM) has a wide range of applications due to high efficiency, high thrust force density and high acceleration. In order to ensure normal operation and maximum output, both the magnetic and thermal performance are vital to be considered. Based on ANSYS software, electromagnetic and thermal finite-element analysis (FEA) models of a 14-pole, 12-slot water-cooled PMLSM are erected adopting suitable assumptions. Firstly, the thrust force and force ripple with different current densities are calculated. Secondly, the influence of different water flow on the motor heat dissipation and force performance under different operationional conditions are investigated and optimized. Furthermore, for continuous operation, the temperature rise and thrust feature are studied under the rated load 8A, the proper temperature $120^{\circ}C$ and the limited temperature $155^{\circ}C$. Likewise, for short-time operation, the maximum duration is calculated when applied with a certain large current. Similarly, for intermittent operation, load time as well as standstill time are determined with the optimal current to achieve better thrust performance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.431-436
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• 2014

In this paper, temperature change properties on the 210kW-class Interior Permanent Magnet Synchronous Motor (IPMSM) are performed with the cooling performance of a water cooling device through the thermal characteristic analysis of the IPMSM considering a real driving pattern of urban railway vehicles. First, the thermal analysis modeling of 210kW-class IPMSM, which is an alternative to the conventional induction motor, and its water cooling device is conducted. Next, the thermal characteristic analysis of the IPMSM considering a real driving pattern of urban railway vehicles is performed using 2-Dimensional FEM tool. Finally, the calculated characteristic results are analyzed. Consequently, it is confirmed that the internal temperature of the 210kW-class IPMSM may be lowered to about 42~52% by maintaining the coolant flow rate of the water cooling device (Cross sectional shape of the pipe has 220mm width and 10mm height) for 0.2kg/s level.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.147-154
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• 2005

A precision hi-directional actuator for a high precision leveling system with $Z{\Theta}_x{\Theta}_y$ motions is proposed and designed in this paper. The actuator is composed of a force generation structure, a guide mechanism, and a symmetric structure. At first, its driving force is generated by a change of flux in air gaps by permanent and changeable flux. The permanent flux is generated by a permanent magnet. The changeable flux is created by variable current flowing through coil. The combination of permanent and changeable flux makes various flux densities in air gaps between moving part and fixed yokes. And then, the difference between flux densities in lower and upper gaps creates forces fur the $bi-direction({\pm}z)$ motion. The guide mechanism of this actuator is composed of two circular plates and one shaft. Reducing motions generated by forces except z-motion, these circular plates endow the actuator with high stiffness for fast settling time. And the function of the shaft is to transfer motion to an object. At last, total body has a symmetric structure to be stable on thermal error. The actuator is designed by MAXWELL 2D and ProMECHANICA. The designed actuator is evaluated by 8nm laser doppler vibrometer, dynamic signal analyzer, and simple PID controller.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.882-887
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• 2014

In this paper, the water cooling method among the forced coolant cooling methods is considered to be applied to the 110kW-class IPMSM for railway vehicles. First, basic thermal property analysis of the IPMSM is conducted using the three-dimensional thermal equivalent network method. Then, based on the results of the basic thermal property analysis, some design requirements for the water cooling jacket are deduced and a basic design of the water cooling jacket is carried out. Finally, thermal equivalent circuit of the water cooling jacket is attached to the IPMSM's 3D thermal equivalent network and then, the basic thermal and effectiveness analysis are conducted for the case of applying the water cooling jacket to the IPMSM. In the future, the thermal variation trends inside the IPMSM by the application of the water cooling jacket is expected to be quickly and easily predicted even at the design step of the railway traction motor.

• Transactions of Materials Processing
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• v.20 no.6
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• pp.439-449
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• 2011

The temperature distribution and subsequent permanent deformation of SS400 carbon steel plate subjected to an induction-based line heating process were studied by a numerical method involving coupled 3-D electromagnetic-thermal-structural analysis. The numerical study revealed that the amount of permanent deformation is strongly related to the Joule loss caused by such process conditions as input power and moving speed of the heat source. To validate the numerical analysis results, line heating experiments were carried out with a high frequency(HF) induction heating(IH) equipment capable of bending thick plate with the moving accuracy of ${\pm}0.1mm$ in heating coil position. The amount of permanent deformation increased with decreasing moving speed and increasing input power.