• Journal of Electrical Engineering and Technology
• /
• v.6 no.2
• /
• pp.208-214
• /
• 2011

In this paper, a characteristics analysis and calculation of the suspending force of a novel bearingless switched reluctance motor (BLSRM) with hybrid stator poles is proposed. The operating principle and permeance are calculated to find an appropriate control scheme for a proposed motor. Furthermore, a mathematical model for suspending force is derived. Finite element analysis is also employed to compare with the expressions for suspending force. Finally, the validity of the structure and the mathematical model is verified by simulation results.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.578-581
• /
• 1987

하이브리드 스텝 모터와 같은 소형 정밀 모터에서 이를 설계 제작하는 과정에서 가공기술의 부족과 높은 생산 단가로 인하여 모든 부분의 가공에 높은 정밀도를 유지하기는 어렵다. 그러므로 토오크 특성에 영향을 많이 미치는 부위의 가공 정밀도를 향상시킴으로써 생산 단가를 줄일 수 있다. 하이브리드 스텝, 모터에서 구조상의 오차는 모터의 PERMEANCE를 변화시키고 PERMEANCE의 변화는 이와 직접적인 관련을 갖고 있는 토오크를 변화시켜서 결국에는 스텝 모터의 가장 중용한 요소인 정확한 위치 제어를 할 수 없게 된다. 모터의 구조적 결함에 대하여 알아보고 이 과정을 통하여 구한 HOLDING 토오크 값으로부터 정상인 때와 구조적인 오차가 있는 경우에 대한 토오크의 최대치와 DETENT 위치를 서로 비교함으로써 오차에 대한 토오크의 영향을 해석한다.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.402-402
• /
• 2000

MFL(Magnetic Flux Leakage) methods are used extensively for inspection of ferromagnetic materials. As an example, pipelines that are buried underground are inspected using MFL methods. By the MFL methods, ferromagnetic pipelines are magnetized by a permanent magnet or an electromagnet and then flux leakage is detected at the defection position. In this paper, we perform modeling of the magnetized pipelines. Also we propose the method localization of th defected areas. The effectiveness of the proposed method is verified experimentally.

• Proceedings of the KIEE Conference
• /
• 2003.07b
• /
• pp.717-719
• /
• 2003

In terms of induction motor analysis, magnetic energy conversion takes place into mechanical energy in air gap. Therefore, flux distribution in air Sap has to be analyzed in detail more than other place of induction motor. In this paper, the air gap permeance of induction motor, which was effected by means of skewed angle and fringing, was analyzed.

• Membrane Journal
• /
• v.31 no.6
• /
• pp.456-470
• /
• 2021

In this study, polyetherimide-based hollow fiber membranes were manufactured using the NIPS (nonsolvent induced phase separation) method. THF, Ethanol, and LiNO₃ were used as additives to control the morphology of the PEI-hollow fiber membranes. Furthermore, for the development of a high hydrogen separation membrane, the spinning conditions were optimized through the characterization of SEM and gas permeance. As a result, as the content of THF increased, the hydrogen/carbon dioxide selectivity increased. However, the permeance decreased due to the trade-off relationship. When ethanol was added, a finger-like structure was shown, and when LiNO₃ was added, a sponge structure was shown. In particular, in the case of a hollow fiber membrane with an optimized PDMS coating layer, the permeance was 40 GPU and the hydrogen/carbon dioxide selectivity was 5.6.

• Applied Chemistry for Engineering
• /
• v.35 no.2
• /
• pp.85-95
• /
• 2024

Direct air capture (DAC) technology plays a crucial role in mitigating climate change. Reports from the International Energy Agency and climate change emphasize its significance, aiming to limit global warming to 1.5 ℃ despite continuous carbon emissions. Despite initial costs, DAC technology demonstrates potential for cost reductions through research and development, operational learning, and economies of scale. Recent advancements in high-permeance polymer membranes indicate the potential of membrane-based DAC technology. However, effective separation of CO₂ from ambient air requires membranes with high selectivity and permeability to CO₂. Current research is focusing on membrane optimization to enhance CO₂ capture efficiency. This study underscores the importance of direct air capture, evolving cost trends, and the pivotal role of membrane development in climate change mitigation efforts. Additionally, this research delved into the theoretical background, conditions, composition, advantages, and disadvantages of permeance and selectivity in membrane-based DAC.

• Membrane Journal
• /
• v.22 no.1
• /
• pp.23-34
• /
• 2012

In this study, we investigated the permeation property of single gases ($N_2$, $O_2$, $SF_6$, $CF_4$ through hollow fiber polymeric membrane (PSF, PC, PI) as a function of pressure and temperature to decide operating condition for $SF_6$ gas separation process. The results showed the gas permeation varied differentlydepending on the properties of gases and membrane. When permeance of each gases was represented as a function of temperature and pressure in 3 dimensional space, the surface of permeance was shown approximately flat. Thus, we established permeance models with forms of first-and second-order polynomial. These two models showed high goodness of fit. This indicates that the two polynomial models have enough applicability to predict the gas separation process.

• Proceedings of the KIEE Conference
• /
• 1990.11a
• /
• pp.58-62
• /
• 1990

Air gap flux density is obtained strictly from air gap permeance and MMF distribution using the design parameter of BLDCM when the stator slot is considered. Then the theoretical equations representing the cogging torque and BEMF are proposed. The effect of skew is described analytically, and skew effect on air gap permeance and MMF is studied. Consequently we verified analytically that skew of slots and magnets influenced on the reduction of the cogging torque and BEMF ripple, and the shape of BEMF.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.1
• /
• pp.1-6
• /
• 2002

Cogging torque is often a principal source of vibration and acoustic noise in high precision spindle motor applications. In this paper, cogging torque is analytically calculated using energy method to show that Fourier spectra of airgap permeance function and airgap MMF function are the most important design parameters to control cogging torque. To control these functions, stator pole shoe pairing and magnet arc design are proposed to minimize cogging torque. As for optimization technique, genetic algorithm is applied to handle trade-off effects of design parameters. Results show that the proposed method can reduce the cogging torque effectively.

• Journal of Advanced Marine Engineering and Technology
• /
• v.20 no.1
• /
• pp.49-55
• /
• 1996

In this paper, the characteristics of a double-sided linear pulse motor (DLPM) with permanent magnet are analysed using the method which combined the coenergy method and the equivalent magnetic circuit method. In the process of computation, the magnetic material nonlinealities of the permanent magnet, the primary and the secondary core are interpolated by the cubic spline method. Then, the equivalent magnetic circuit modelled by the permeance method including airgap reluctance, which is a function of displacement, is obtained. The static thrust which is the derivative of coenergy is computed by Newton Raphson method at each dispacement. And, in order to investigate the characteristics of the DLPM, the thrust shows as a function of displacement, input current and air gap. The simulation resuls are compared with experimental ones obtained from the DLPM with 2 phase and 4 poles.