• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.3
• /
• pp.34-39
• /
• 2008

The purpose of this paper is characteristic analysis of multi-disk axial-gap pm motor for turbo compressor. The axial-gap permanent magnet motor has shown a growing interest in high-speed application for its high-efficiency, compact size and low vibration characteristics due to core-less structure. To achieve high-power, the axial-gap PM motor has multi-disk structure of stator and rotor disk. Because of its complicated magnetic flux path, it is not easy to calculate a dynamic characteristics using finite element analysis. In this paper, the simplified 2-D unfolded model to predict EMF characteristic is presented. To verify thesuggested 2-D unfolded model analysis of back-EMF characteristic was calculated and compared 3-D finite element. Finally the proposed method is verified by experimental results and shows good agreement with test results.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.3
• /
• pp.249-257
• /
• 2015

A fuel assembly consists of fuel rods composed of pellets (UO2) and a cladding tube (Zircaloy). The role of the fuel rods in the reactor is to generate heat by nuclear fission, as well as to retain fission products during operation. A simulation method using a computer program was used to evaluate the safety of the nuclear fuel rods. This computer program has been called the fuel performance code. In the analysis of a light water reactor fuel rod, the gap conductance, which depended on the distance between the pellets and cladding tube, mainly influenced the thermomechanical behavior of the fuel rod. In this work, a 3D gap element was proposed to simulate the thermo-mechanical behavior of the nuclear fuel rod, considering the gap conductance. To implement the proposed 3D gap element, a 3D thermo-mechanical module was also developed using FORTRAN90. The asymmetric characteristics of the nuclear fuel rod, such as the MPS (missing pellet surface) and eccentricity, were simulated to evaluate the proposed 3D gap element.

• Journal of Information Technology Applications and Management
• /
• v.24 no.2
• /
• pp.97-112
• /
• 2017

This paper aims to research the technology level of sports industry, through analyzing the technology gap between Korea and other major countries (USA, Europe, Japan, and China), and provide a list of technologies to be prioritized for R&D investment by conducting an analysis of the strategic importance of various element technologies. The results of the analysis showed that the technology level of Korean sports industry currently stands at 70.5% of the country with the most advanced technology (the USA), and that the technology gap amounts to 4.8 years. It was also found that the USA is the country with the most advanced technology (100%) at present, followed by Europe (91.1%), Japan (88.3%), Korea (70.5%), and China (61.2%). To reduce the technology gap, we established a Strategic Zone (SZ) and derived three element technologies including 'design and production technologies for sports and game equipment' in the $1^{st}$ tier, nine element technologies including '3D motion analysis and simulation technology' in the $2^{nd}$ tier, and four element technologies including 'fitness/health promotion and management technology' in the $3^{rd}$ tier. The significance of this research is that it included five major technology categories of the sports industry in its analysis, selected an expert on sports industry technologies using the delphi method. Therefore, the results of this study may be suitable for use as basic data in establishing the R&D strategy for the future development of the sports industry.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.954-956
• /
• 2005

For transformer designers, eddy current loss calculation of steel structure is required to consider temperature rise on transformers. This study describes design of a lock plate for converter transformers by finite element method. The lock plate may be locally heated by fringing flux due to air-gap. 3D finite element analysis is performed and compared so as to minimize eddy loss on the lock plate with different materials and structures

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.997-998
• /
• 2007

This paper deals with analytical solution concerning the image method using the magnetic charge instead of 3D FEA(finite element analysis) in the slotless single air-gap motor. The theory of analytical method and the design procedures are introduced. The reliability and validity of proposed analytical solution are verified through the comparison with the results of commercial 3D FE software. In addition, calculation time between proposed analytical solution and 3D FEA is compared. Finally, characteristics, such as Back-EMF and phase resistance, between calculated and experimental results are compared. From the verification with 3D FEA and experimental results, it is proved that presented analytical method provided very effective and precise results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.5
• /
• pp.486-487
• /
• 1997

This paper presents the pure capacitive lumped element equivalent circuits for several coplanar waveguide(CPW) discontinuities such as an open-end, an open-end with connected ground planes, a gap and an open-end CPW stub and gives their capacitive element values as a function of physical dimensions of the discontinuity and the frequency for a specific substrate. The capacitive element values are determined from the scattering parameters which are obtained using the finite-difference time-domain(FDTD) method. For an open-end, an open-end with connected ground planes and a gap, the numerical results of the FDTD are compared with the quasi-static results which are calculated using the three- dimensional finite difference method(3D-FDM).

• Journal of Magnetics
• /
• v.18 no.3
• /
• pp.260-267
• /
• 2013

In this paper a general 2-D model of a large air-gap synchronous machine either with non-magnetic or magnetic core rotor is investigated and electrical characteristics of the machine are analytically calculated. Considering the general model, analytical equations for magnetic field density in different regions of the large air-gap machine are calculated. In addition, self and mutual inductances in the proposed model of the machine have been developed, which are the most important parameters in the electromagnetic design and transient analysis of synchronous machines. Finite element simulation has also been performed to verify the obtained results from the equations. Analytical results show good agreement with FEM results.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.4
• /
• pp.667-676
• /
• 2002

Many studies on the finite element modeling for bolted joints have proceeded, but the structures with bolted joints are complicated in shape and it is difficult to find out the characteristics according to joint condition. Usually, experimental methods have been used for bolted joint analysis. A reliable and practical finite element modeling technique for structure with bolted joints is very important for engineers in industry. In this study, three kinds of model are presented; a detailed model, a practical model and a simple model. The detailed model is modeled by using 3-D solid element and gap element, and the practical model is modeled by using shell element (a portion of bolt head) and beam element (a portion of bolt body), the simple model is modeled by simplifying practical model without using gap elements. Among these models, the simple model has the least degree of freedom and show the effect of memory reduction of 59%, when compared with the detailed model.

• Journal of Magnetics
• /
• v.20 no.1
• /
• pp.91-96
• /
• 2015

As many researchers are relentlessly trying to improve the power generation schemes from the power grid, to meet the constantly increasing electricity demand. In this paper, the results of a finite element analysis are carried out to study on a design optimization of an asymmetric air-gap structure in 3-phase Permanent Magnet Brushless DC Motors. To achieve a high efficiency for a 3-phase PM BLDC motor, the asymmetric air-gap structure is proposed considering the rotation direction of a motor. Generally, a single-phase BLDC motor is applied asymmetric air-gap structure for starting. This is because the asymmetric air-gap structure causes reluctance variation so the motor can utilize reluctance torque toward a rotation direction. In this paper, the asymmetric air-gap is applied to 3-phase BLDC SPM motor so it utilizes reluctance torque with alignment torque. A proposed model is designed by 2-D FE analysis and the results are verified by experimental test.

• Proceedings of the KIEE Conference
• /
• 2002.11d
• /
• pp.124-127
• /
• 2002

This paper presents a 3D shape optimization algorithm for electromagnetic devices using the design sensitivity analysis with finite element method. The structural deformation analysis based on the deformation theory of the elastic body under stress is used for mesh renewing. The design sensitivity and adjoint variable formulae are derived for the 3D nonlinear finite element method with edge element. The proposed algorithm is applied to the shape optimization of 3D electromagnet to get a uniform flux density at the air gap.