• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1197-1198
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• 2008

There have been few papers using finite element method(FEM) to analyze arc driving force for spiral type vacuum interrupter electrode up to date while there have been many papers dealing with AMF type electrode by means of FEM. AMF analysis is very important in AMF type electrode because it has proportional relation with effective area which means the area of magnetic flux density above critical magnetic flux density to diffuse arc. In the same manner, arc driving force is an important factor to drive arc by Lorentz force. In this paper two models were calculated and compared by using commercial FEM software Maxwell 3D.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.356-363
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• 2011

Vibrations and noise in electrical machines are directly related to the characteristics of the radial forces on one hand, and mechanical behavior on the other [1, 4]. The characteristics of these forces depend on the air gap flux density, which is also influenced by other factors, such as stator slots and poles, saturation level, winding type, and certain faults. The aim of this work is to investigate the effect of eccentricity and demagnetization faults on electromagnetic noise generated by the external surface of Permanent Magnet Synchronous Machine [PMSM]. For this purpose, an analytical electromagnetic vibroacoustic model is developed. The results confirm the effect of eccentricity and demagnetization fault in generating some low modes radial forces.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.25-27
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• 2005

This paper deals with the comparison and analysis of brushless DC (BLDC) motor with radial and polar anisotropic plastic magnet. The open-circuit field distributions and back-emf for BLDC motor with polar plastic magnet are established analytically and the results are validated extensively by comparison with finite element (FE) analyses. On the basis of two dimensional (2-D) analytical solutions, this paper predicts open-circuit field characteristics according to design parameters and makes a comparison between BLDC motor with polar plastic magnet and it with radial plastic magnet in terms of required magnet volume and harmonic of air-gap flux density waveform.

• Journal of Magnetics
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• v.21 no.3
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• pp.387-392
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• 2016

Lower flux leakage designs have become important in the development of microspeakers used in thin and miniaturized mobile phones. We propose four methods to reduce the flux leakage of the magnetic circuit in a microspeaker. Optimization was performed based on the proposed approach by using the response surface method. Electromagnetic analyses were conducted using the finite element method. Experimental results are in good agreement with the simulated results obtained in one degree-of-freedom analysis from 100 to 5 kHz. Both the simulated and experimental results confirm that one of the proposed methods is much more effective in reducing flux leakage than the other methods. In the optimized method, compared with a default approach, the average radial flux density in the air gap decreased only by 5.5%, the maximum flux leakage was reduced by 28.6%, and the acoustic performance at primary resonance decreased by 0.45 dB, which gap is indiscernible to the human ear.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.868-870
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• 2001

Salient pole rotor type single phase SRM(switched reluctance motor) can be use axial direction magnetic flux and radial direction magnetic flux at the same time. Then, it has higher energy density per unit volume and can be lessened the shaft length of motor or exciting magnetic force. Additionally, it's durability is good because it is simple structure and driving device. Prototype of Salient pole rotor type single phase SRM was fabricated by using parameters of three phase SRM and 3D FEM analysis. Also, driving device was fabricated for prototype. Speed and torque characteristic was confirmed through the experiments, and flux linkage, which is important parameter of SRM for generating torque, was measured. The induction emf was calculated by using ideal inductance graph and current graph. Calculated emf and measured emf was compared for confirming loss of prototype in this paper.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.669-670
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• 2015

In this paper, rotor design modification of a novel proposed machine termed the Axial Flux Doubly Fed Reluctance Machine (AF-BDFRM) is studied. The main potential advantage of AF-BDFRM is that it has larger torque and power density compared to radial flux-BDFRM. However, with the general rotor pole shape, this machine output back EMF has high THD % and high cogging torque. This paper studies the rotor design modification in the proposed AF-BDFRM to reduce the THD % in inducedd back EMF and cogging torque. Also the transient 3D finite element analysis (FEA) optimization of initial design is presented.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.194-196
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• 1999

This paper verifies that DSPSRM having the rotor pole of "ㅓ" shape has a radial and axial flux distribution, and analyzes the flux density distribution of each direction using 3D FEM.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.125-128
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• 2008

Atomization characteristics of small LRE-injector spray are investigated by using dual-mode phase Doppler anemometry (DPDA). Velocity, size, number density, and volume flux were measured at various injection pressures along the radial distance to make a close inquiry into spatial distribution characteristic of spray droplets. As the injection pressure increases, the velocity, turbulence intensity, number density, and volume flux of spray droplets become higher, whereas the droplet size ($D_{10}$ or $D_{32}$) gets smaller. Also, velocity and volume flux are proportional to Sauter mean diameter (SMD, $D_{32}$).

• Journal of ILASS-Korea
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• v.28 no.2
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• pp.97-104
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• 2023

A sprinkler is a fire suppression system that extinguishes combustible materials in the early stages of a fire, creating a spray. However, spray formation method of the sprinkler can result in an uneven distribution of water spray on the surface of combustible materials. It is necessary to ensure a consistent water flux density regardless of the spray direction and angle. In this study, the water flux distribution was analyzed for the various types of sprinkler head: circular, flush, pendent, and upright types. All sprinkler heads have a K-factor of 80 LPM/(0.1MPa)^0.5. In this study, water collection cubes were used to examine the water flux distribution. The upright type sprinkler head showed a low standard deviation in total sprayed area, indicating a high level of uniformity. The upright type head showed the lowest standard deviation in the radial direction, and also showed the lowest standard deviation in the azimuthal direction. Upright sprinkler head has no obstructing structure along the path of droplets after they are generated. For this reason, upright sprinkler head showed the most uniform water flux distribution on the floor.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.724-725
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• 2015

본 논문에서는 모터의 방사계 소음 진동에 영향을 미치는 표면전자기력의 발생 매커니즘을 확인하고자 한다. 고정자 표면에서 발생하는 전자기력 가운데 토크에 기여하지 않는 성분을 구분하기 위해 전자리겨 성분을 Radial과 Tangential방향으로 나눈다. 이 중 토크에 기여하지 않는 Radial방향의 힘을 발생시키는 Tangential Flux Density성분의 분포를 확인하고, 자속 포화도 분포와 어떠한 관계가 있는지 확인한다. 모터의 자속밀도 및 전자기력에 대한 계산은 유한요소해석을 기반으로 한 수치 해석기법을 통해 수행하였다.