• 전기학회논문지
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• 제59권3호
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• pp.609-613
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• 2010

In this paper, we optimized and simulated the heatsink of 75W LED module for street lighting and evaluated the optical properties with the manufactured heatsink. the structure of LED package make simple as chip and heatslug and thermal flow is analyzed by using the FEM(Finite Element Method) with CFdesign V10. Also, we measured the temperature of heatsink and evaluated the optical properties with infrared thermal image camera and integrated sphere system for luminous flux in $1\;[m^3]$ box. As results, Heatsink optimized in 3 mm pin thickness, 6 mm base thickness and 16 number of pin count by using Heatsink-designer and got the results which is the temperature of $47.37\;[^{\circ}C]$ and thermal resistance of $0.48407\;[W/^{\circ}C]$. In thermal flow simulation, the temperature of heatsink decreased from $51.54\;[^{\circ}C]$ to $51.51\;[^{\circ}C]$ and the temperature of heatsink by the time in real measurement decreased from $47.03\;[^{\circ}C]$ to $46.87\;[^{\circ}C]$. Moreover, we improve 0.68 % in the decreased ratio of the luminous flux.

• Journal of Electrical Engineering and Technology
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• 제7권5호
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• pp.745-752
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• 2012

Transverse flux machine (TFM) has been proved to be very suitable for high-torque, low-speed, and direct-drive situation in industry. But the complex structures and costly permanent magnets (PMs) are two key limitations of its wide range of applications. This paper proposes a new claw pole TFM (ACPTFM) which features an assembled claw pole stator and using the lamination steels material to overcome the complex structures. By combining response surface methodology (RSM) with design of experiment, an optimum design method is put forward to improve the PM's contribution to the torque in order to save the PM's amount. The optimum design results demonstrate the validity of the proposed optimum design method and the optimized model. Eventually, the finite-element analysis (FEA) calculation method, which is used in the optimization process, is verified by the experiments in a prototype.

• Journal of Magnetics
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• 제20권3호
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• pp.265-272
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• 2015

In recent years, flux switching machines (FSMs) have been an attractive research topic owing to their tremendous advantages of robust rotor structure, high torque, and high power capability suitable for intensive applications. However, most of the investigations are focusing on the inner-rotor structure, which is incongruous for direct drive applications. In this study, high torque and power densities of a new 12S-14P outer-rotor permanent magnet (PM) FSM with a DC excitation coil was investigated based on two-dimensional finite element analysis for in-wheel direct drive electric vehicle (EV). Based on some design restrictions and specifications, design refinements were conducted on the original design machine by using the deterministic optimization approach. With only 1.0 kg PM, the final design machine achieved the maximum torque and power densities of 12.4 Nm/kg and 5.93 kW/kg, respectively, slightly better than the inner-rotor HEFSM and interior PM synchronous machine design for EV.

• 한국표면공학회지
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• 제43권3호
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• pp.159-164
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• 2010

Surface roughness of deposited or etched film strongly depends on ion bombardment. Relationships between ion bombardment variables and surface roughness are too complicated to model analytically. To overcome this, an empirical neural network model was constructed and applied to a deposition process of silicon nitride (SiN) films. The films were deposited by using a pulsed plasma enhanced chemical vapor deposition system in $SiH_4$-$NH_4$ plasma. Radio frequency source power and duty ratio were varied in the range of 200-800 W and 40-100%. A total of 20 experiments were conducted. A non-invasive ion energy analyzer was used to collect ion energy distribution. The diagnostic variables examined include high (or) low ion energy and high (or low) ion energy flux. Mean surface roughness was measured by using atomic force microscopy. A neural network model relating the diagnostic variables to the surface roughness was constructed and its prediction performance was optimized by using a genetic algorithm. The optimized model yielded an improved performance of about 58% over statistical regression model. The model revealed very interesting features useful for optimization of surface roughness. This includes a reduction in surface roughness either by an increase in ion energy flux at lower ion energy or by an increase in higher ion energy at lower ion energy flux.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.869-876
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• 2018

The force of a direct current (DC) electromagnetic pump used to transport liquid lithium was analyzed to optimize its geometrical and electrical parameters by numerical simulation. In a heavy-ion accelerator, which is being developed in Korea, a liquid lithium film is utilized for its high charge-stripping efficiency for heavy ions of uranium. A DC electromagnetic pump with a flow rate of $6cm^3/s$ and a developed pressure of 1.5 MPa at a temperature of $200^{\circ}C$ was required to circulate the liquid lithium to form liquid lithium films. The current and magnetic flux densities in the flow gap, where a $Sm_2Co_{17}$ permanent magnet was used to generate a magnetic field, were analyzed for the electromagnetic force distribution generated in the pump. The pressure developed by the Lorentz force on the electromagnetic force was calculated by considering the electromotive force and hydraulic pressure drop in the narrow flow channel. The opposite force at the end part due to the magnetic flux density in the opposite direction depended on the pump geometrical parameters such as the pump duct length and width that defines the rectangular channels in the nonhomogeneous distributions of the current and magnetic fields.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 추계학술대회 논문집
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• pp.23-24
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• 2013

In recent years, ISG (Integrated Starter and Generator) system receives a great attention for electric electrification of normal gasoline vehicle. As a cost-effect machine design, an ISG without a permanent magnet is considered. A 12slot-10pole field-excitation flux-switching synchronous machine (FEFSSM) is designed and analyzed via JMAG. The active parts such as the field excitation coil and armature coil are located on the stator. The rotor part consisting of single piece iron makes it more robust and suitable to apply for high speed motor drive system application coupled with reduction belt. The design target is the motor with a maximum torque of 40Nm, a maximum power of 10kW and a maximum speed of 14000 rpm. In this paper, design optimization method is proposed for high torque capability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.158-160
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• 2006

The structure of interior permanent magnet type brushless DC motor (IPM type BLDC motor) has high saliency ratios that produce additional reluctance torque. But this structure has a significant cogging torque that may cause acoustic noise and vibration. In this paper describes an optimization of flux barrier in order to reduce cogging torque and torque ripple in IPM type BLDC motor using the Taguchi methods. The optimal design consider- ed noises such as manufacturing tolerances of permanent magnet size. So, optimal design ensures that torque performance is insensitive to noise.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1980-1990
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• 2017

A study on the multi-objective optimization of Interior Permanent-Magnet Synchronous Motors (IPMSMs) with 2, 3, 4 and 5 flux barriers per magnetic pole, based on Genetic Algorithm (GA) is presented by considering the aspect of irreversible demagnetization. Applying the 2004 Toyota Prius single-layer IPMSM as the reference machine, the asymmetrical two-, three-, four- and five-layer rotor models with the same amount of Permanent-Magnets (PMs) is presented to improve the torque characteristics, i.e., reducing the torque pulsation and increasing the average torque. A reduction of the torque pulsations is achieved by adopting different and asymmetrical flux barrier geometries in each magnetic pole of the rotor topology. The demagnetization performance in the PMs is considered as well as the motor performance; and analyzed by using finite element method (FEM) for verification of the optimal solutions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.862-863
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• 2015

This paper presents an improved estimation procedure for the contribution to no-load flux linkage created by the permanent magnet (PM) in interior permanent magnet synchronous machines. In the proposed method, the saturation effect in stator and rotor cores are taken into account by utilizing the frozen permeability method (FPM). This improved procedure can evaluate the contribution for each local element in the PM to the no-load flux linkage. According to the analysis results, an effective PM topology optimal design can be carried out to achieve high utilization ratio of PM in the machine. In order to determine the threshold of the low contribution of PM for removing, one multi-objective optimization model is proposed. Based on the optimal threshold, the final optimal topology design of PM can be achieved.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.618-621
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• 2008

The magnetic recording system shows the difference of the magnetic recording density according to the direction of the magnetic field. The yoke shape of the recording system affects the magnetic field direction; therefore, the recording density may be raised by changing the shape. This paper intends not only to increase the magnetic flux density of the record region but also to reduce the recording loss of a specific region through the simultaneous design of the yoke and the magnet. The recording loss can be reduced by minimizing the magnetic flux of the adjacent area to the recording region. The topology optimization method is used to obtain the optimal shape both of the yoke and the magnet. And the commercial package, Maxwell is used to verify the result.