• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1535-1540
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• 2013

In this paper, the Radial Magnetic Force(RMF) and cogging torque which cause vibration and noise in IPM type BLDC motor were analyzed. The cogging torque and RMF cause electromagnetic vibration. So, a notch was installed for the equilibrium of RMF and cogging torque reduction. The notch was analyzed by using a Fourier Series for the energy distribution of the air-gap. The equilibrium of RMF and the reduction of cogging torque were performed by a Design Of Experiment(DOE) with the notch. Also, operating characteristics and efficiency were analyzed and compared.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.2
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• pp.298-303
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• 2016

In this paper, the vibration source of IPM type BLDC motor was analyzed by finite element method. The main causes of the electrical vibration were RMF(Radial magnetic force) and cogging torque. It was designed model of minimized cogging torque and RMF equilibrium. Design models were selected the optimum model using the design of experiment method. And, the vibration experiment was carried out through prototype machine of each model. Finally, the experimental results were compared with the analysis ones.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.480-480
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• 2008

Vacuum circuit breaker(VCB) is now emerging as an alternative of gas circuit breaker(GCB) which uses SF6 gas as insulating material whose dielectric strength is outstanding. But we have to reduce SF6 gas because SF6 gas is one of greenhouse gas and efforts to reduce greenhouse gas are now trend of the world. Therefore, we can say VCB is the optimal alternative of GCB because vacuum is environmentally friendly. The vacuum interrupter is the core part of VCB to interrupt arcing current. There are mainly two methods to extinguish arc. One is radial magnetic field (RMF) method and the other is axial magnetic field (AMF) method. We deals with RMF method in this paper. Compared with AMP, RMF arc quenching method has different principle to extinguish arc. In case of RMF method, pinch effect is much larger than AMF method. Because of pinch effect RMF type contact electrodes have the single large spot which is severly damaged and melted while AMF type contact electrodes have small and multiple spots which are slightly damaged and melted. To prevent contact electrode being damaged and melted from high temperature-arc, RMF method uses Lorentz force to move arc. In this paper we calculated and compared the arc driving force of two cases and we analyzed the force acting on each part of arc by means of commercial finite element method software Maxwell 3D. They have 3petals and we considered two cases. One is the case when fixed(upper) and movable(lower) contacts are in mirror arrangement (Case 1). The other is the case when one of two contacts (movable contact) is revolved at maximum angle as possible as it can be (Case 2). And at each case above, we analyzed arc driving force at two positions, position 1 is the closest to the center of contact and position 2 is near the edge of petal on fixed contact. As a result we could find that Case 2 generated stronger arc driving force than Case 1 at position 1. But at position 2 Case 1 generated stronger arc driving force than Case 2. This simulation method can contribute to optimizing spiral-type electrode designs in a view of arc driving force.

• Journal of the Korea Computer Graphics Society
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• v.16 no.4
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• pp.41-50
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• 2010

We present a new technique for multilevel editing of hierarchical B-spline curves. At each level, control points of a displacement function are expressed in the rotation minimizing frames (RMFs) [1] which are computed on nodal points of the curve at previous level. When the curve is edited at previous level, the corresponding RMFs are updated and the control points of the displacement function at current level are applied to the new RMFs, which maintains the relative details of the curve at current level to those of previous level. We demonstrate the effectiveness and robustness of the proposed technique using several experimental results.

• Earthquakes and Structures
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• v.12 no.6
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• pp.643-652
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• 2017

One of the methods to strengthen the structures against the seismic lateral loading is the employment of the composite columns. A concrete-filled tube (CFT) has the cumulative advantages of steel and concrete. Concrete-filled steel tube columns have been widely used in the moment-resisting frame (MRF) structures, located in both non-seismic zones and high-risk seismic zones. In this paper, the results of studies on two important seismic parameters of ductility and the response modification factor (RMF) of the MRFs with CFT columns are submitted. While the studies are carried out, the effects of span length-story height ratio, the strength of materials and seismic behavior of MRFs are considered. In this regard, the ductility, RMF and the strength of 36 models of the steel MRFs with CFTs are analyzed. The fiber plastic hinges numerical simulation and pushover analysis method are used in the calculations. Based on the obtained results, the RMFs suitable for the 5-, 10- and 15- story frames are proposed.

• Journal of Magnetics
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• v.22 no.2
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• pp.333-343
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• 2017

A rotating magnetic field (RMF) ${\Phi}_1-{\Phi}_2$ model was developed in consideration of the skin effect. The rotating magnetic field's induced three-dimensional flow was simulated numerically, and the influence of the skin effect was investigated. The rotating magnetic field drives the rotating convection in the azimuthal direction, and a secondary convection appears in the radial-meridional direction. The results indicate that ignoring the skin effect results in a smaller azimuthal velocity component and larger radial and axial velocity components, and that the deviation becomes more obvious with the larger dimensionless shielding parameter K.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.4
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• pp.383-388
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• 2014

In This paper, the output characteristics and vibrations were compared and analyzed according to operation method in 100W class. The voltage source is applied only two phase in BLDC drive system therefore commutation torque ripple and imbalance of RMF occurred. Due to this efficiency was significantly degraded because mechanical loss is increased, besides the vibration and noise were greatly generated. The vibration and output characteristics were compared and analyzed according to three phase and BLDC drive system.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1155-1158
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• 2007

이 논문에서는 VPN QoS 서비스 모델인 Hose 모델 기반의 자원예약을 지원하기 위해 NSIS 시그널링 프로토콜을 사용하여 네트워크 자원을 예약하고 관리하는 모델인 Hose-NSIS-QoSM을 제안한다. 구체적으로 Hose-NSIS-QoSM에서 자원예약을 위해 새로이 요구되는 NSIS 메시지 객체, 각 NSIS 노드에서의 메시지 전달 및 처리과정, QoS NSLP 상태 테이블을 정의하였고, 자원 관리를 위해 RMF 상태 테이블을 정의하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05e
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• pp.19-22
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• 2003

In this paper, we performed analysis of electric field, magnetic field, current density in AMF electrode using the Maxwell 3D simulation. The current distribution and magnetic field in simple models are analyzed to verify its efficiency and accuracy. In the vicinity of the slits of axial magnetic field type electrode a comparatively high axial magnetic flux density existsIn addition the validity of FEM is confirmed by performing the analyses of distribution in current density and magnetic flux density.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.5
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• pp.772-777
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• 2017

In this paper, the goal of optimization design is efficiency increase and vibration optimization. For this purpose, shape optimization design was performed using Quasi-Newton method, which is one of optimization techniques, and it was verified through finite element analysis In addition, modal analysis of the stator was performed to estimate the natural frequency. through the vibration experiment, the vibration was verified for cogging torque and RMF analysis. Finally, optimal and basic models were compared and analyzed for efficeincy characteristics.